Commit | Line | Data |
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ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
ed3d261b JP |
29 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
30 | ||
ddbcc7e8 | 31 | #include <linux/cgroup.h> |
2ce9738b | 32 | #include <linux/cred.h> |
c6d57f33 | 33 | #include <linux/ctype.h> |
ddbcc7e8 | 34 | #include <linux/errno.h> |
2ce9738b | 35 | #include <linux/init_task.h> |
ddbcc7e8 PM |
36 | #include <linux/kernel.h> |
37 | #include <linux/list.h> | |
c9482a5b | 38 | #include <linux/magic.h> |
ddbcc7e8 PM |
39 | #include <linux/mm.h> |
40 | #include <linux/mutex.h> | |
41 | #include <linux/mount.h> | |
42 | #include <linux/pagemap.h> | |
a424316c | 43 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
44 | #include <linux/rcupdate.h> |
45 | #include <linux/sched.h> | |
ddbcc7e8 | 46 | #include <linux/slab.h> |
ddbcc7e8 | 47 | #include <linux/spinlock.h> |
1ed13287 | 48 | #include <linux/percpu-rwsem.h> |
ddbcc7e8 | 49 | #include <linux/string.h> |
bbcb81d0 | 50 | #include <linux/sort.h> |
81a6a5cd | 51 | #include <linux/kmod.h> |
846c7bb0 BS |
52 | #include <linux/delayacct.h> |
53 | #include <linux/cgroupstats.h> | |
0ac801fe | 54 | #include <linux/hashtable.h> |
096b7fe0 | 55 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 56 | #include <linux/idr.h> |
d1d9fd33 | 57 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
c4c27fbd | 58 | #include <linux/kthread.h> |
776f02fa | 59 | #include <linux/delay.h> |
60063497 | 60 | #include <linux/atomic.h> |
e93ad19d | 61 | #include <linux/cpuset.h> |
bd1060a1 | 62 | #include <net/sock.h> |
ddbcc7e8 | 63 | |
b1a21367 TH |
64 | /* |
65 | * pidlists linger the following amount before being destroyed. The goal | |
66 | * is avoiding frequent destruction in the middle of consecutive read calls | |
67 | * Expiring in the middle is a performance problem not a correctness one. | |
68 | * 1 sec should be enough. | |
69 | */ | |
70 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ | |
71 | ||
8d7e6fb0 TH |
72 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
73 | MAX_CFTYPE_NAME + 2) | |
74 | ||
e25e2cbb TH |
75 | /* |
76 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
77 | * hierarchy must be performed while holding it. | |
78 | * | |
f0d9a5f1 | 79 | * css_set_lock protects task->cgroups pointer, the list of css_set |
0e1d768f | 80 | * objects, and the chain of tasks off each css_set. |
e25e2cbb | 81 | * |
0e1d768f TH |
82 | * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
83 | * cgroup.h can use them for lockdep annotations. | |
e25e2cbb | 84 | */ |
2219449a TH |
85 | #ifdef CONFIG_PROVE_RCU |
86 | DEFINE_MUTEX(cgroup_mutex); | |
f0d9a5f1 | 87 | DEFINE_SPINLOCK(css_set_lock); |
0e1d768f | 88 | EXPORT_SYMBOL_GPL(cgroup_mutex); |
f0d9a5f1 | 89 | EXPORT_SYMBOL_GPL(css_set_lock); |
2219449a | 90 | #else |
81a6a5cd | 91 | static DEFINE_MUTEX(cgroup_mutex); |
f0d9a5f1 | 92 | static DEFINE_SPINLOCK(css_set_lock); |
2219449a TH |
93 | #endif |
94 | ||
6fa4918d | 95 | /* |
15a4c835 TH |
96 | * Protects cgroup_idr and css_idr so that IDs can be released without |
97 | * grabbing cgroup_mutex. | |
6fa4918d TH |
98 | */ |
99 | static DEFINE_SPINLOCK(cgroup_idr_lock); | |
100 | ||
34c06254 TH |
101 | /* |
102 | * Protects cgroup_file->kn for !self csses. It synchronizes notifications | |
103 | * against file removal/re-creation across css hiding. | |
104 | */ | |
105 | static DEFINE_SPINLOCK(cgroup_file_kn_lock); | |
106 | ||
69e943b7 TH |
107 | /* |
108 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires | |
109 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. | |
110 | */ | |
111 | static DEFINE_SPINLOCK(release_agent_path_lock); | |
81a6a5cd | 112 | |
1ed13287 TH |
113 | struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
114 | ||
8353da1f | 115 | #define cgroup_assert_mutex_or_rcu_locked() \ |
f78f5b90 PM |
116 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
117 | !lockdep_is_held(&cgroup_mutex), \ | |
8353da1f | 118 | "cgroup_mutex or RCU read lock required"); |
780cd8b3 | 119 | |
e5fca243 TH |
120 | /* |
121 | * cgroup destruction makes heavy use of work items and there can be a lot | |
122 | * of concurrent destructions. Use a separate workqueue so that cgroup | |
123 | * destruction work items don't end up filling up max_active of system_wq | |
124 | * which may lead to deadlock. | |
125 | */ | |
126 | static struct workqueue_struct *cgroup_destroy_wq; | |
127 | ||
b1a21367 TH |
128 | /* |
129 | * pidlist destructions need to be flushed on cgroup destruction. Use a | |
130 | * separate workqueue as flush domain. | |
131 | */ | |
132 | static struct workqueue_struct *cgroup_pidlist_destroy_wq; | |
133 | ||
3ed80a62 | 134 | /* generate an array of cgroup subsystem pointers */ |
073219e9 | 135 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
3ed80a62 | 136 | static struct cgroup_subsys *cgroup_subsys[] = { |
ddbcc7e8 PM |
137 | #include <linux/cgroup_subsys.h> |
138 | }; | |
073219e9 TH |
139 | #undef SUBSYS |
140 | ||
141 | /* array of cgroup subsystem names */ | |
142 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, | |
143 | static const char *cgroup_subsys_name[] = { | |
ddbcc7e8 PM |
144 | #include <linux/cgroup_subsys.h> |
145 | }; | |
073219e9 | 146 | #undef SUBSYS |
ddbcc7e8 | 147 | |
49d1dc4b TH |
148 | /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
149 | #define SUBSYS(_x) \ | |
150 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ | |
151 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ | |
152 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ | |
153 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); | |
154 | #include <linux/cgroup_subsys.h> | |
155 | #undef SUBSYS | |
156 | ||
157 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, | |
158 | static struct static_key_true *cgroup_subsys_enabled_key[] = { | |
159 | #include <linux/cgroup_subsys.h> | |
160 | }; | |
161 | #undef SUBSYS | |
162 | ||
163 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, | |
164 | static struct static_key_true *cgroup_subsys_on_dfl_key[] = { | |
165 | #include <linux/cgroup_subsys.h> | |
166 | }; | |
167 | #undef SUBSYS | |
168 | ||
ddbcc7e8 | 169 | /* |
3dd06ffa | 170 | * The default hierarchy, reserved for the subsystems that are otherwise |
9871bf95 TH |
171 | * unattached - it never has more than a single cgroup, and all tasks are |
172 | * part of that cgroup. | |
ddbcc7e8 | 173 | */ |
a2dd4247 | 174 | struct cgroup_root cgrp_dfl_root; |
d0ec4230 | 175 | EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
9871bf95 | 176 | |
a2dd4247 TH |
177 | /* |
178 | * The default hierarchy always exists but is hidden until mounted for the | |
179 | * first time. This is for backward compatibility. | |
180 | */ | |
a7165264 | 181 | static bool cgrp_dfl_visible; |
ddbcc7e8 | 182 | |
223ffb29 | 183 | /* Controllers blocked by the commandline in v1 */ |
6e5c8307 | 184 | static u16 cgroup_no_v1_mask; |
223ffb29 | 185 | |
5533e011 | 186 | /* some controllers are not supported in the default hierarchy */ |
a7165264 | 187 | static u16 cgrp_dfl_inhibit_ss_mask; |
5533e011 | 188 | |
ddbcc7e8 PM |
189 | /* The list of hierarchy roots */ |
190 | ||
9871bf95 TH |
191 | static LIST_HEAD(cgroup_roots); |
192 | static int cgroup_root_count; | |
ddbcc7e8 | 193 | |
3417ae1f | 194 | /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
1a574231 | 195 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 196 | |
794611a1 | 197 | /* |
0cb51d71 TH |
198 | * Assign a monotonically increasing serial number to csses. It guarantees |
199 | * cgroups with bigger numbers are newer than those with smaller numbers. | |
200 | * Also, as csses are always appended to the parent's ->children list, it | |
201 | * guarantees that sibling csses are always sorted in the ascending serial | |
202 | * number order on the list. Protected by cgroup_mutex. | |
794611a1 | 203 | */ |
0cb51d71 | 204 | static u64 css_serial_nr_next = 1; |
794611a1 | 205 | |
cb4a3167 AS |
206 | /* |
207 | * These bitmask flags indicate whether tasks in the fork and exit paths have | |
208 | * fork/exit handlers to call. This avoids us having to do extra work in the | |
209 | * fork/exit path to check which subsystems have fork/exit callbacks. | |
ddbcc7e8 | 210 | */ |
6e5c8307 TH |
211 | static u16 have_fork_callback __read_mostly; |
212 | static u16 have_exit_callback __read_mostly; | |
213 | static u16 have_free_callback __read_mostly; | |
ddbcc7e8 | 214 | |
7e47682e | 215 | /* Ditto for the can_fork callback. */ |
6e5c8307 | 216 | static u16 have_canfork_callback __read_mostly; |
7e47682e | 217 | |
67e9c74b | 218 | static struct file_system_type cgroup2_fs_type; |
a14c6874 TH |
219 | static struct cftype cgroup_dfl_base_files[]; |
220 | static struct cftype cgroup_legacy_base_files[]; | |
628f7cd4 | 221 | |
6e5c8307 | 222 | static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask); |
ed27b9f7 | 223 | static void css_task_iter_advance(struct css_task_iter *it); |
42809dd4 | 224 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
6cd0f5bb TH |
225 | static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
226 | struct cgroup_subsys *ss); | |
9d755d33 | 227 | static void css_release(struct percpu_ref *ref); |
f8f22e53 | 228 | static void kill_css(struct cgroup_subsys_state *css); |
4df8dc90 TH |
229 | static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
230 | struct cgroup *cgrp, struct cftype cfts[], | |
2bb566cb | 231 | bool is_add); |
42809dd4 | 232 | |
fc5ed1e9 TH |
233 | /** |
234 | * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID | |
235 | * @ssid: subsys ID of interest | |
236 | * | |
237 | * cgroup_subsys_enabled() can only be used with literal subsys names which | |
238 | * is fine for individual subsystems but unsuitable for cgroup core. This | |
239 | * is slower static_key_enabled() based test indexed by @ssid. | |
240 | */ | |
241 | static bool cgroup_ssid_enabled(int ssid) | |
242 | { | |
243 | return static_key_enabled(cgroup_subsys_enabled_key[ssid]); | |
244 | } | |
245 | ||
223ffb29 JW |
246 | static bool cgroup_ssid_no_v1(int ssid) |
247 | { | |
248 | return cgroup_no_v1_mask & (1 << ssid); | |
249 | } | |
250 | ||
9e10a130 TH |
251 | /** |
252 | * cgroup_on_dfl - test whether a cgroup is on the default hierarchy | |
253 | * @cgrp: the cgroup of interest | |
254 | * | |
255 | * The default hierarchy is the v2 interface of cgroup and this function | |
256 | * can be used to test whether a cgroup is on the default hierarchy for | |
257 | * cases where a subsystem should behave differnetly depending on the | |
258 | * interface version. | |
259 | * | |
260 | * The set of behaviors which change on the default hierarchy are still | |
261 | * being determined and the mount option is prefixed with __DEVEL__. | |
262 | * | |
263 | * List of changed behaviors: | |
264 | * | |
265 | * - Mount options "noprefix", "xattr", "clone_children", "release_agent" | |
266 | * and "name" are disallowed. | |
267 | * | |
268 | * - When mounting an existing superblock, mount options should match. | |
269 | * | |
270 | * - Remount is disallowed. | |
271 | * | |
272 | * - rename(2) is disallowed. | |
273 | * | |
274 | * - "tasks" is removed. Everything should be at process granularity. Use | |
275 | * "cgroup.procs" instead. | |
276 | * | |
277 | * - "cgroup.procs" is not sorted. pids will be unique unless they got | |
278 | * recycled inbetween reads. | |
279 | * | |
280 | * - "release_agent" and "notify_on_release" are removed. Replacement | |
281 | * notification mechanism will be implemented. | |
282 | * | |
283 | * - "cgroup.clone_children" is removed. | |
284 | * | |
285 | * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup | |
286 | * and its descendants contain no task; otherwise, 1. The file also | |
287 | * generates kernfs notification which can be monitored through poll and | |
288 | * [di]notify when the value of the file changes. | |
289 | * | |
290 | * - cpuset: tasks will be kept in empty cpusets when hotplug happens and | |
291 | * take masks of ancestors with non-empty cpus/mems, instead of being | |
292 | * moved to an ancestor. | |
293 | * | |
294 | * - cpuset: a task can be moved into an empty cpuset, and again it takes | |
295 | * masks of ancestors. | |
296 | * | |
297 | * - memcg: use_hierarchy is on by default and the cgroup file for the flag | |
298 | * is not created. | |
299 | * | |
300 | * - blkcg: blk-throttle becomes properly hierarchical. | |
301 | * | |
302 | * - debug: disallowed on the default hierarchy. | |
303 | */ | |
304 | static bool cgroup_on_dfl(const struct cgroup *cgrp) | |
305 | { | |
306 | return cgrp->root == &cgrp_dfl_root; | |
307 | } | |
308 | ||
6fa4918d TH |
309 | /* IDR wrappers which synchronize using cgroup_idr_lock */ |
310 | static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, | |
311 | gfp_t gfp_mask) | |
312 | { | |
313 | int ret; | |
314 | ||
315 | idr_preload(gfp_mask); | |
54504e97 | 316 | spin_lock_bh(&cgroup_idr_lock); |
d0164adc | 317 | ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM); |
54504e97 | 318 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
319 | idr_preload_end(); |
320 | return ret; | |
321 | } | |
322 | ||
323 | static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) | |
324 | { | |
325 | void *ret; | |
326 | ||
54504e97 | 327 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 328 | ret = idr_replace(idr, ptr, id); |
54504e97 | 329 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
330 | return ret; |
331 | } | |
332 | ||
333 | static void cgroup_idr_remove(struct idr *idr, int id) | |
334 | { | |
54504e97 | 335 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 336 | idr_remove(idr, id); |
54504e97 | 337 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
338 | } |
339 | ||
d51f39b0 TH |
340 | static struct cgroup *cgroup_parent(struct cgroup *cgrp) |
341 | { | |
342 | struct cgroup_subsys_state *parent_css = cgrp->self.parent; | |
343 | ||
344 | if (parent_css) | |
345 | return container_of(parent_css, struct cgroup, self); | |
346 | return NULL; | |
347 | } | |
348 | ||
5531dc91 TH |
349 | /* subsystems visibly enabled on a cgroup */ |
350 | static u16 cgroup_control(struct cgroup *cgrp) | |
351 | { | |
352 | struct cgroup *parent = cgroup_parent(cgrp); | |
353 | u16 root_ss_mask = cgrp->root->subsys_mask; | |
354 | ||
355 | if (parent) | |
356 | return parent->subtree_control; | |
357 | ||
358 | if (cgroup_on_dfl(cgrp)) | |
359 | root_ss_mask &= ~cgrp_dfl_inhibit_ss_mask; | |
360 | ||
361 | return root_ss_mask; | |
362 | } | |
363 | ||
364 | /* subsystems enabled on a cgroup */ | |
365 | static u16 cgroup_ss_mask(struct cgroup *cgrp) | |
366 | { | |
367 | struct cgroup *parent = cgroup_parent(cgrp); | |
368 | ||
369 | if (parent) | |
370 | return parent->subtree_ss_mask; | |
371 | ||
372 | return cgrp->root->subsys_mask; | |
373 | } | |
374 | ||
95109b62 TH |
375 | /** |
376 | * cgroup_css - obtain a cgroup's css for the specified subsystem | |
377 | * @cgrp: the cgroup of interest | |
9d800df1 | 378 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
95109b62 | 379 | * |
ca8bdcaf TH |
380 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
381 | * function must be called either under cgroup_mutex or rcu_read_lock() and | |
382 | * the caller is responsible for pinning the returned css if it wants to | |
383 | * keep accessing it outside the said locks. This function may return | |
384 | * %NULL if @cgrp doesn't have @subsys_id enabled. | |
95109b62 TH |
385 | */ |
386 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, | |
ca8bdcaf | 387 | struct cgroup_subsys *ss) |
95109b62 | 388 | { |
ca8bdcaf | 389 | if (ss) |
aec25020 | 390 | return rcu_dereference_check(cgrp->subsys[ss->id], |
ace2bee8 | 391 | lockdep_is_held(&cgroup_mutex)); |
ca8bdcaf | 392 | else |
9d800df1 | 393 | return &cgrp->self; |
95109b62 | 394 | } |
42809dd4 | 395 | |
aec3dfcb TH |
396 | /** |
397 | * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem | |
398 | * @cgrp: the cgroup of interest | |
9d800df1 | 399 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
aec3dfcb | 400 | * |
d0f702e6 | 401 | * Similar to cgroup_css() but returns the effective css, which is defined |
aec3dfcb TH |
402 | * as the matching css of the nearest ancestor including self which has @ss |
403 | * enabled. If @ss is associated with the hierarchy @cgrp is on, this | |
404 | * function is guaranteed to return non-NULL css. | |
405 | */ | |
406 | static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, | |
407 | struct cgroup_subsys *ss) | |
408 | { | |
409 | lockdep_assert_held(&cgroup_mutex); | |
410 | ||
411 | if (!ss) | |
9d800df1 | 412 | return &cgrp->self; |
aec3dfcb | 413 | |
eeecbd19 TH |
414 | /* |
415 | * This function is used while updating css associations and thus | |
5531dc91 | 416 | * can't test the csses directly. Test ss_mask. |
eeecbd19 | 417 | */ |
5531dc91 | 418 | while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) { |
d51f39b0 | 419 | cgrp = cgroup_parent(cgrp); |
5531dc91 TH |
420 | if (!cgrp) |
421 | return NULL; | |
422 | } | |
aec3dfcb TH |
423 | |
424 | return cgroup_css(cgrp, ss); | |
95109b62 | 425 | } |
42809dd4 | 426 | |
eeecbd19 TH |
427 | /** |
428 | * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem | |
429 | * @cgrp: the cgroup of interest | |
430 | * @ss: the subsystem of interest | |
431 | * | |
432 | * Find and get the effective css of @cgrp for @ss. The effective css is | |
433 | * defined as the matching css of the nearest ancestor including self which | |
434 | * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, | |
435 | * the root css is returned, so this function always returns a valid css. | |
436 | * The returned css must be put using css_put(). | |
437 | */ | |
438 | struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, | |
439 | struct cgroup_subsys *ss) | |
440 | { | |
441 | struct cgroup_subsys_state *css; | |
442 | ||
443 | rcu_read_lock(); | |
444 | ||
445 | do { | |
446 | css = cgroup_css(cgrp, ss); | |
447 | ||
448 | if (css && css_tryget_online(css)) | |
449 | goto out_unlock; | |
450 | cgrp = cgroup_parent(cgrp); | |
451 | } while (cgrp); | |
452 | ||
453 | css = init_css_set.subsys[ss->id]; | |
454 | css_get(css); | |
455 | out_unlock: | |
456 | rcu_read_unlock(); | |
457 | return css; | |
458 | } | |
459 | ||
ddbcc7e8 | 460 | /* convenient tests for these bits */ |
54766d4a | 461 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 462 | { |
184faf32 | 463 | return !(cgrp->self.flags & CSS_ONLINE); |
ddbcc7e8 PM |
464 | } |
465 | ||
052c3f3a TH |
466 | static void cgroup_get(struct cgroup *cgrp) |
467 | { | |
468 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); | |
469 | css_get(&cgrp->self); | |
470 | } | |
471 | ||
472 | static bool cgroup_tryget(struct cgroup *cgrp) | |
473 | { | |
474 | return css_tryget(&cgrp->self); | |
475 | } | |
476 | ||
b4168640 | 477 | struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
59f5296b | 478 | { |
2bd59d48 | 479 | struct cgroup *cgrp = of->kn->parent->priv; |
b4168640 | 480 | struct cftype *cft = of_cft(of); |
2bd59d48 TH |
481 | |
482 | /* | |
483 | * This is open and unprotected implementation of cgroup_css(). | |
484 | * seq_css() is only called from a kernfs file operation which has | |
485 | * an active reference on the file. Because all the subsystem | |
486 | * files are drained before a css is disassociated with a cgroup, | |
487 | * the matching css from the cgroup's subsys table is guaranteed to | |
488 | * be and stay valid until the enclosing operation is complete. | |
489 | */ | |
490 | if (cft->ss) | |
491 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
492 | else | |
9d800df1 | 493 | return &cgrp->self; |
59f5296b | 494 | } |
b4168640 | 495 | EXPORT_SYMBOL_GPL(of_css); |
59f5296b | 496 | |
e9685a03 | 497 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 498 | { |
bd89aabc | 499 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
500 | } |
501 | ||
1c6727af TH |
502 | /** |
503 | * for_each_css - iterate all css's of a cgroup | |
504 | * @css: the iteration cursor | |
505 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
506 | * @cgrp: the target cgroup to iterate css's of | |
507 | * | |
aec3dfcb | 508 | * Should be called under cgroup_[tree_]mutex. |
1c6727af TH |
509 | */ |
510 | #define for_each_css(css, ssid, cgrp) \ | |
511 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
512 | if (!((css) = rcu_dereference_check( \ | |
513 | (cgrp)->subsys[(ssid)], \ | |
514 | lockdep_is_held(&cgroup_mutex)))) { } \ | |
515 | else | |
516 | ||
aec3dfcb TH |
517 | /** |
518 | * for_each_e_css - iterate all effective css's of a cgroup | |
519 | * @css: the iteration cursor | |
520 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
521 | * @cgrp: the target cgroup to iterate css's of | |
522 | * | |
523 | * Should be called under cgroup_[tree_]mutex. | |
524 | */ | |
525 | #define for_each_e_css(css, ssid, cgrp) \ | |
526 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
527 | if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ | |
528 | ; \ | |
529 | else | |
530 | ||
30159ec7 | 531 | /** |
3ed80a62 | 532 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 533 | * @ss: the iteration cursor |
780cd8b3 | 534 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 535 | */ |
780cd8b3 | 536 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
537 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
538 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 539 | |
cb4a3167 | 540 | /** |
b4e0eeaf | 541 | * do_each_subsys_mask - filter for_each_subsys with a bitmask |
cb4a3167 AS |
542 | * @ss: the iteration cursor |
543 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end | |
b4e0eeaf | 544 | * @ss_mask: the bitmask |
cb4a3167 AS |
545 | * |
546 | * The block will only run for cases where the ssid-th bit (1 << ssid) of | |
b4e0eeaf | 547 | * @ss_mask is set. |
cb4a3167 | 548 | */ |
b4e0eeaf TH |
549 | #define do_each_subsys_mask(ss, ssid, ss_mask) do { \ |
550 | unsigned long __ss_mask = (ss_mask); \ | |
551 | if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \ | |
4a705c5c | 552 | (ssid) = 0; \ |
b4e0eeaf TH |
553 | break; \ |
554 | } \ | |
555 | for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \ | |
556 | (ss) = cgroup_subsys[ssid]; \ | |
557 | { | |
558 | ||
559 | #define while_each_subsys_mask() \ | |
560 | } \ | |
561 | } \ | |
562 | } while (false) | |
cb4a3167 | 563 | |
985ed670 TH |
564 | /* iterate across the hierarchies */ |
565 | #define for_each_root(root) \ | |
5549c497 | 566 | list_for_each_entry((root), &cgroup_roots, root_list) |
ddbcc7e8 | 567 | |
f8f22e53 TH |
568 | /* iterate over child cgrps, lock should be held throughout iteration */ |
569 | #define cgroup_for_each_live_child(child, cgrp) \ | |
d5c419b6 | 570 | list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
8353da1f | 571 | if (({ lockdep_assert_held(&cgroup_mutex); \ |
f8f22e53 TH |
572 | cgroup_is_dead(child); })) \ |
573 | ; \ | |
574 | else | |
7ae1bad9 | 575 | |
81a6a5cd | 576 | static void cgroup_release_agent(struct work_struct *work); |
bd89aabc | 577 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 578 | |
69d0206c TH |
579 | /* |
580 | * A cgroup can be associated with multiple css_sets as different tasks may | |
581 | * belong to different cgroups on different hierarchies. In the other | |
582 | * direction, a css_set is naturally associated with multiple cgroups. | |
583 | * This M:N relationship is represented by the following link structure | |
584 | * which exists for each association and allows traversing the associations | |
585 | * from both sides. | |
586 | */ | |
587 | struct cgrp_cset_link { | |
588 | /* the cgroup and css_set this link associates */ | |
589 | struct cgroup *cgrp; | |
590 | struct css_set *cset; | |
591 | ||
592 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
593 | struct list_head cset_link; | |
594 | ||
595 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
596 | struct list_head cgrp_link; | |
817929ec PM |
597 | }; |
598 | ||
172a2c06 TH |
599 | /* |
600 | * The default css_set - used by init and its children prior to any | |
817929ec PM |
601 | * hierarchies being mounted. It contains a pointer to the root state |
602 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
603 | * reference-counted, to improve performance when child cgroups | |
604 | * haven't been created. | |
605 | */ | |
5024ae29 | 606 | struct css_set init_css_set = { |
172a2c06 TH |
607 | .refcount = ATOMIC_INIT(1), |
608 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), | |
609 | .tasks = LIST_HEAD_INIT(init_css_set.tasks), | |
610 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), | |
611 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), | |
612 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), | |
ed27b9f7 | 613 | .task_iters = LIST_HEAD_INIT(init_css_set.task_iters), |
172a2c06 | 614 | }; |
817929ec | 615 | |
172a2c06 | 616 | static int css_set_count = 1; /* 1 for init_css_set */ |
817929ec | 617 | |
0de0942d TH |
618 | /** |
619 | * css_set_populated - does a css_set contain any tasks? | |
620 | * @cset: target css_set | |
621 | */ | |
622 | static bool css_set_populated(struct css_set *cset) | |
623 | { | |
f0d9a5f1 | 624 | lockdep_assert_held(&css_set_lock); |
0de0942d TH |
625 | |
626 | return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks); | |
627 | } | |
628 | ||
842b597e TH |
629 | /** |
630 | * cgroup_update_populated - updated populated count of a cgroup | |
631 | * @cgrp: the target cgroup | |
632 | * @populated: inc or dec populated count | |
633 | * | |
0de0942d TH |
634 | * One of the css_sets associated with @cgrp is either getting its first |
635 | * task or losing the last. Update @cgrp->populated_cnt accordingly. The | |
636 | * count is propagated towards root so that a given cgroup's populated_cnt | |
637 | * is zero iff the cgroup and all its descendants don't contain any tasks. | |
842b597e TH |
638 | * |
639 | * @cgrp's interface file "cgroup.populated" is zero if | |
640 | * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt | |
641 | * changes from or to zero, userland is notified that the content of the | |
642 | * interface file has changed. This can be used to detect when @cgrp and | |
643 | * its descendants become populated or empty. | |
644 | */ | |
645 | static void cgroup_update_populated(struct cgroup *cgrp, bool populated) | |
646 | { | |
f0d9a5f1 | 647 | lockdep_assert_held(&css_set_lock); |
842b597e TH |
648 | |
649 | do { | |
650 | bool trigger; | |
651 | ||
652 | if (populated) | |
653 | trigger = !cgrp->populated_cnt++; | |
654 | else | |
655 | trigger = !--cgrp->populated_cnt; | |
656 | ||
657 | if (!trigger) | |
658 | break; | |
659 | ||
ad2ed2b3 | 660 | check_for_release(cgrp); |
6f60eade TH |
661 | cgroup_file_notify(&cgrp->events_file); |
662 | ||
d51f39b0 | 663 | cgrp = cgroup_parent(cgrp); |
842b597e TH |
664 | } while (cgrp); |
665 | } | |
666 | ||
0de0942d TH |
667 | /** |
668 | * css_set_update_populated - update populated state of a css_set | |
669 | * @cset: target css_set | |
670 | * @populated: whether @cset is populated or depopulated | |
671 | * | |
672 | * @cset is either getting the first task or losing the last. Update the | |
673 | * ->populated_cnt of all associated cgroups accordingly. | |
674 | */ | |
675 | static void css_set_update_populated(struct css_set *cset, bool populated) | |
676 | { | |
677 | struct cgrp_cset_link *link; | |
678 | ||
f0d9a5f1 | 679 | lockdep_assert_held(&css_set_lock); |
0de0942d TH |
680 | |
681 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) | |
682 | cgroup_update_populated(link->cgrp, populated); | |
683 | } | |
684 | ||
f6d7d049 TH |
685 | /** |
686 | * css_set_move_task - move a task from one css_set to another | |
687 | * @task: task being moved | |
688 | * @from_cset: css_set @task currently belongs to (may be NULL) | |
689 | * @to_cset: new css_set @task is being moved to (may be NULL) | |
690 | * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks | |
691 | * | |
692 | * Move @task from @from_cset to @to_cset. If @task didn't belong to any | |
693 | * css_set, @from_cset can be NULL. If @task is being disassociated | |
694 | * instead of moved, @to_cset can be NULL. | |
695 | * | |
ed27b9f7 TH |
696 | * This function automatically handles populated_cnt updates and |
697 | * css_task_iter adjustments but the caller is responsible for managing | |
698 | * @from_cset and @to_cset's reference counts. | |
f6d7d049 TH |
699 | */ |
700 | static void css_set_move_task(struct task_struct *task, | |
701 | struct css_set *from_cset, struct css_set *to_cset, | |
702 | bool use_mg_tasks) | |
703 | { | |
f0d9a5f1 | 704 | lockdep_assert_held(&css_set_lock); |
f6d7d049 | 705 | |
20b454a6 TH |
706 | if (to_cset && !css_set_populated(to_cset)) |
707 | css_set_update_populated(to_cset, true); | |
708 | ||
f6d7d049 | 709 | if (from_cset) { |
ed27b9f7 TH |
710 | struct css_task_iter *it, *pos; |
711 | ||
f6d7d049 | 712 | WARN_ON_ONCE(list_empty(&task->cg_list)); |
ed27b9f7 TH |
713 | |
714 | /* | |
715 | * @task is leaving, advance task iterators which are | |
716 | * pointing to it so that they can resume at the next | |
717 | * position. Advancing an iterator might remove it from | |
718 | * the list, use safe walk. See css_task_iter_advance*() | |
719 | * for details. | |
720 | */ | |
721 | list_for_each_entry_safe(it, pos, &from_cset->task_iters, | |
722 | iters_node) | |
723 | if (it->task_pos == &task->cg_list) | |
724 | css_task_iter_advance(it); | |
725 | ||
f6d7d049 TH |
726 | list_del_init(&task->cg_list); |
727 | if (!css_set_populated(from_cset)) | |
728 | css_set_update_populated(from_cset, false); | |
729 | } else { | |
730 | WARN_ON_ONCE(!list_empty(&task->cg_list)); | |
731 | } | |
732 | ||
733 | if (to_cset) { | |
734 | /* | |
735 | * We are synchronized through cgroup_threadgroup_rwsem | |
736 | * against PF_EXITING setting such that we can't race | |
737 | * against cgroup_exit() changing the css_set to | |
738 | * init_css_set and dropping the old one. | |
739 | */ | |
740 | WARN_ON_ONCE(task->flags & PF_EXITING); | |
741 | ||
f6d7d049 TH |
742 | rcu_assign_pointer(task->cgroups, to_cset); |
743 | list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks : | |
744 | &to_cset->tasks); | |
745 | } | |
746 | } | |
747 | ||
7717f7ba PM |
748 | /* |
749 | * hash table for cgroup groups. This improves the performance to find | |
750 | * an existing css_set. This hash doesn't (currently) take into | |
751 | * account cgroups in empty hierarchies. | |
752 | */ | |
472b1053 | 753 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 754 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 755 | |
0ac801fe | 756 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 757 | { |
0ac801fe | 758 | unsigned long key = 0UL; |
30159ec7 TH |
759 | struct cgroup_subsys *ss; |
760 | int i; | |
472b1053 | 761 | |
30159ec7 | 762 | for_each_subsys(ss, i) |
0ac801fe LZ |
763 | key += (unsigned long)css[i]; |
764 | key = (key >> 16) ^ key; | |
472b1053 | 765 | |
0ac801fe | 766 | return key; |
472b1053 LZ |
767 | } |
768 | ||
a25eb52e | 769 | static void put_css_set_locked(struct css_set *cset) |
b4f48b63 | 770 | { |
69d0206c | 771 | struct cgrp_cset_link *link, *tmp_link; |
2d8f243a TH |
772 | struct cgroup_subsys *ss; |
773 | int ssid; | |
5abb8855 | 774 | |
f0d9a5f1 | 775 | lockdep_assert_held(&css_set_lock); |
89c5509b TH |
776 | |
777 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 778 | return; |
81a6a5cd | 779 | |
53254f90 TH |
780 | /* This css_set is dead. unlink it and release cgroup and css refs */ |
781 | for_each_subsys(ss, ssid) { | |
2d8f243a | 782 | list_del(&cset->e_cset_node[ssid]); |
53254f90 TH |
783 | css_put(cset->subsys[ssid]); |
784 | } | |
5abb8855 | 785 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
786 | css_set_count--; |
787 | ||
69d0206c | 788 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
69d0206c TH |
789 | list_del(&link->cset_link); |
790 | list_del(&link->cgrp_link); | |
2ceb231b TH |
791 | if (cgroup_parent(link->cgrp)) |
792 | cgroup_put(link->cgrp); | |
2c6ab6d2 | 793 | kfree(link); |
81a6a5cd | 794 | } |
2c6ab6d2 | 795 | |
5abb8855 | 796 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
797 | } |
798 | ||
a25eb52e | 799 | static void put_css_set(struct css_set *cset) |
89c5509b TH |
800 | { |
801 | /* | |
802 | * Ensure that the refcount doesn't hit zero while any readers | |
803 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
804 | * rwlock | |
805 | */ | |
806 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
807 | return; | |
808 | ||
f0d9a5f1 | 809 | spin_lock_bh(&css_set_lock); |
a25eb52e | 810 | put_css_set_locked(cset); |
f0d9a5f1 | 811 | spin_unlock_bh(&css_set_lock); |
89c5509b TH |
812 | } |
813 | ||
817929ec PM |
814 | /* |
815 | * refcounted get/put for css_set objects | |
816 | */ | |
5abb8855 | 817 | static inline void get_css_set(struct css_set *cset) |
817929ec | 818 | { |
5abb8855 | 819 | atomic_inc(&cset->refcount); |
817929ec PM |
820 | } |
821 | ||
b326f9d0 | 822 | /** |
7717f7ba | 823 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
824 | * @cset: candidate css_set being tested |
825 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
826 | * @new_cgrp: cgroup that's being entered by the task |
827 | * @template: desired set of css pointers in css_set (pre-calculated) | |
828 | * | |
6f4b7e63 | 829 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
830 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
831 | */ | |
5abb8855 TH |
832 | static bool compare_css_sets(struct css_set *cset, |
833 | struct css_set *old_cset, | |
7717f7ba PM |
834 | struct cgroup *new_cgrp, |
835 | struct cgroup_subsys_state *template[]) | |
836 | { | |
837 | struct list_head *l1, *l2; | |
838 | ||
aec3dfcb TH |
839 | /* |
840 | * On the default hierarchy, there can be csets which are | |
841 | * associated with the same set of cgroups but different csses. | |
842 | * Let's first ensure that csses match. | |
843 | */ | |
844 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) | |
7717f7ba | 845 | return false; |
7717f7ba PM |
846 | |
847 | /* | |
848 | * Compare cgroup pointers in order to distinguish between | |
aec3dfcb TH |
849 | * different cgroups in hierarchies. As different cgroups may |
850 | * share the same effective css, this comparison is always | |
851 | * necessary. | |
7717f7ba | 852 | */ |
69d0206c TH |
853 | l1 = &cset->cgrp_links; |
854 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 855 | while (1) { |
69d0206c | 856 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 857 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
858 | |
859 | l1 = l1->next; | |
860 | l2 = l2->next; | |
861 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
862 | if (l1 == &cset->cgrp_links) { |
863 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
864 | break; |
865 | } else { | |
69d0206c | 866 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
867 | } |
868 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
869 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
870 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
871 | cgrp1 = link1->cgrp; | |
872 | cgrp2 = link2->cgrp; | |
7717f7ba | 873 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 874 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
875 | |
876 | /* | |
877 | * If this hierarchy is the hierarchy of the cgroup | |
878 | * that's changing, then we need to check that this | |
879 | * css_set points to the new cgroup; if it's any other | |
880 | * hierarchy, then this css_set should point to the | |
881 | * same cgroup as the old css_set. | |
882 | */ | |
5abb8855 TH |
883 | if (cgrp1->root == new_cgrp->root) { |
884 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
885 | return false; |
886 | } else { | |
5abb8855 | 887 | if (cgrp1 != cgrp2) |
7717f7ba PM |
888 | return false; |
889 | } | |
890 | } | |
891 | return true; | |
892 | } | |
893 | ||
b326f9d0 TH |
894 | /** |
895 | * find_existing_css_set - init css array and find the matching css_set | |
896 | * @old_cset: the css_set that we're using before the cgroup transition | |
897 | * @cgrp: the cgroup that we're moving into | |
898 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 899 | */ |
5abb8855 TH |
900 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
901 | struct cgroup *cgrp, | |
902 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 903 | { |
3dd06ffa | 904 | struct cgroup_root *root = cgrp->root; |
30159ec7 | 905 | struct cgroup_subsys *ss; |
5abb8855 | 906 | struct css_set *cset; |
0ac801fe | 907 | unsigned long key; |
b326f9d0 | 908 | int i; |
817929ec | 909 | |
aae8aab4 BB |
910 | /* |
911 | * Build the set of subsystem state objects that we want to see in the | |
912 | * new css_set. while subsystems can change globally, the entries here | |
913 | * won't change, so no need for locking. | |
914 | */ | |
30159ec7 | 915 | for_each_subsys(ss, i) { |
f392e51c | 916 | if (root->subsys_mask & (1UL << i)) { |
aec3dfcb TH |
917 | /* |
918 | * @ss is in this hierarchy, so we want the | |
919 | * effective css from @cgrp. | |
920 | */ | |
921 | template[i] = cgroup_e_css(cgrp, ss); | |
817929ec | 922 | } else { |
aec3dfcb TH |
923 | /* |
924 | * @ss is not in this hierarchy, so we don't want | |
925 | * to change the css. | |
926 | */ | |
5abb8855 | 927 | template[i] = old_cset->subsys[i]; |
817929ec PM |
928 | } |
929 | } | |
930 | ||
0ac801fe | 931 | key = css_set_hash(template); |
5abb8855 TH |
932 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
933 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
934 | continue; |
935 | ||
936 | /* This css_set matches what we need */ | |
5abb8855 | 937 | return cset; |
472b1053 | 938 | } |
817929ec PM |
939 | |
940 | /* No existing cgroup group matched */ | |
941 | return NULL; | |
942 | } | |
943 | ||
69d0206c | 944 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 945 | { |
69d0206c | 946 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 947 | |
69d0206c TH |
948 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
949 | list_del(&link->cset_link); | |
36553434 LZ |
950 | kfree(link); |
951 | } | |
952 | } | |
953 | ||
69d0206c TH |
954 | /** |
955 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
956 | * @count: the number of links to allocate | |
957 | * @tmp_links: list_head the allocated links are put on | |
958 | * | |
959 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
960 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 961 | */ |
69d0206c | 962 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 963 | { |
69d0206c | 964 | struct cgrp_cset_link *link; |
817929ec | 965 | int i; |
69d0206c TH |
966 | |
967 | INIT_LIST_HEAD(tmp_links); | |
968 | ||
817929ec | 969 | for (i = 0; i < count; i++) { |
f4f4be2b | 970 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 971 | if (!link) { |
69d0206c | 972 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
973 | return -ENOMEM; |
974 | } | |
69d0206c | 975 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
976 | } |
977 | return 0; | |
978 | } | |
979 | ||
c12f65d4 LZ |
980 | /** |
981 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 982 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 983 | * @cset: the css_set to be linked |
c12f65d4 LZ |
984 | * @cgrp: the destination cgroup |
985 | */ | |
69d0206c TH |
986 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
987 | struct cgroup *cgrp) | |
c12f65d4 | 988 | { |
69d0206c | 989 | struct cgrp_cset_link *link; |
c12f65d4 | 990 | |
69d0206c | 991 | BUG_ON(list_empty(tmp_links)); |
6803c006 TH |
992 | |
993 | if (cgroup_on_dfl(cgrp)) | |
994 | cset->dfl_cgrp = cgrp; | |
995 | ||
69d0206c TH |
996 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
997 | link->cset = cset; | |
7717f7ba | 998 | link->cgrp = cgrp; |
842b597e | 999 | |
7717f7ba | 1000 | /* |
389b9c1b TH |
1001 | * Always add links to the tail of the lists so that the lists are |
1002 | * in choronological order. | |
7717f7ba | 1003 | */ |
389b9c1b | 1004 | list_move_tail(&link->cset_link, &cgrp->cset_links); |
69d0206c | 1005 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
2ceb231b TH |
1006 | |
1007 | if (cgroup_parent(cgrp)) | |
1008 | cgroup_get(cgrp); | |
c12f65d4 LZ |
1009 | } |
1010 | ||
b326f9d0 TH |
1011 | /** |
1012 | * find_css_set - return a new css_set with one cgroup updated | |
1013 | * @old_cset: the baseline css_set | |
1014 | * @cgrp: the cgroup to be updated | |
1015 | * | |
1016 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
1017 | * substituted into the appropriate hierarchy. | |
817929ec | 1018 | */ |
5abb8855 TH |
1019 | static struct css_set *find_css_set(struct css_set *old_cset, |
1020 | struct cgroup *cgrp) | |
817929ec | 1021 | { |
b326f9d0 | 1022 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 1023 | struct css_set *cset; |
69d0206c TH |
1024 | struct list_head tmp_links; |
1025 | struct cgrp_cset_link *link; | |
2d8f243a | 1026 | struct cgroup_subsys *ss; |
0ac801fe | 1027 | unsigned long key; |
2d8f243a | 1028 | int ssid; |
472b1053 | 1029 | |
b326f9d0 TH |
1030 | lockdep_assert_held(&cgroup_mutex); |
1031 | ||
817929ec PM |
1032 | /* First see if we already have a cgroup group that matches |
1033 | * the desired set */ | |
f0d9a5f1 | 1034 | spin_lock_bh(&css_set_lock); |
5abb8855 TH |
1035 | cset = find_existing_css_set(old_cset, cgrp, template); |
1036 | if (cset) | |
1037 | get_css_set(cset); | |
f0d9a5f1 | 1038 | spin_unlock_bh(&css_set_lock); |
817929ec | 1039 | |
5abb8855 TH |
1040 | if (cset) |
1041 | return cset; | |
817929ec | 1042 | |
f4f4be2b | 1043 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 1044 | if (!cset) |
817929ec PM |
1045 | return NULL; |
1046 | ||
69d0206c | 1047 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 1048 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 1049 | kfree(cset); |
817929ec PM |
1050 | return NULL; |
1051 | } | |
1052 | ||
5abb8855 | 1053 | atomic_set(&cset->refcount, 1); |
69d0206c | 1054 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 1055 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 1056 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 1057 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 1058 | INIT_LIST_HEAD(&cset->mg_node); |
ed27b9f7 | 1059 | INIT_LIST_HEAD(&cset->task_iters); |
5abb8855 | 1060 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
1061 | |
1062 | /* Copy the set of subsystem state objects generated in | |
1063 | * find_existing_css_set() */ | |
5abb8855 | 1064 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 1065 | |
f0d9a5f1 | 1066 | spin_lock_bh(&css_set_lock); |
817929ec | 1067 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 1068 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 1069 | struct cgroup *c = link->cgrp; |
69d0206c | 1070 | |
7717f7ba PM |
1071 | if (c->root == cgrp->root) |
1072 | c = cgrp; | |
69d0206c | 1073 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 1074 | } |
817929ec | 1075 | |
69d0206c | 1076 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 1077 | |
817929ec | 1078 | css_set_count++; |
472b1053 | 1079 | |
2d8f243a | 1080 | /* Add @cset to the hash table */ |
5abb8855 TH |
1081 | key = css_set_hash(cset->subsys); |
1082 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 1083 | |
53254f90 TH |
1084 | for_each_subsys(ss, ssid) { |
1085 | struct cgroup_subsys_state *css = cset->subsys[ssid]; | |
1086 | ||
2d8f243a | 1087 | list_add_tail(&cset->e_cset_node[ssid], |
53254f90 TH |
1088 | &css->cgroup->e_csets[ssid]); |
1089 | css_get(css); | |
1090 | } | |
2d8f243a | 1091 | |
f0d9a5f1 | 1092 | spin_unlock_bh(&css_set_lock); |
817929ec | 1093 | |
5abb8855 | 1094 | return cset; |
b4f48b63 PM |
1095 | } |
1096 | ||
3dd06ffa | 1097 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
7717f7ba | 1098 | { |
3dd06ffa | 1099 | struct cgroup *root_cgrp = kf_root->kn->priv; |
2bd59d48 | 1100 | |
3dd06ffa | 1101 | return root_cgrp->root; |
2bd59d48 TH |
1102 | } |
1103 | ||
3dd06ffa | 1104 | static int cgroup_init_root_id(struct cgroup_root *root) |
f2e85d57 TH |
1105 | { |
1106 | int id; | |
1107 | ||
1108 | lockdep_assert_held(&cgroup_mutex); | |
1109 | ||
985ed670 | 1110 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
f2e85d57 TH |
1111 | if (id < 0) |
1112 | return id; | |
1113 | ||
1114 | root->hierarchy_id = id; | |
1115 | return 0; | |
1116 | } | |
1117 | ||
3dd06ffa | 1118 | static void cgroup_exit_root_id(struct cgroup_root *root) |
f2e85d57 TH |
1119 | { |
1120 | lockdep_assert_held(&cgroup_mutex); | |
1121 | ||
1122 | if (root->hierarchy_id) { | |
1123 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
1124 | root->hierarchy_id = 0; | |
1125 | } | |
1126 | } | |
1127 | ||
3dd06ffa | 1128 | static void cgroup_free_root(struct cgroup_root *root) |
f2e85d57 TH |
1129 | { |
1130 | if (root) { | |
d0f702e6 | 1131 | /* hierarchy ID should already have been released */ |
f2e85d57 TH |
1132 | WARN_ON_ONCE(root->hierarchy_id); |
1133 | ||
1134 | idr_destroy(&root->cgroup_idr); | |
1135 | kfree(root); | |
1136 | } | |
1137 | } | |
1138 | ||
3dd06ffa | 1139 | static void cgroup_destroy_root(struct cgroup_root *root) |
59f5296b | 1140 | { |
3dd06ffa | 1141 | struct cgroup *cgrp = &root->cgrp; |
f2e85d57 | 1142 | struct cgrp_cset_link *link, *tmp_link; |
f2e85d57 | 1143 | |
2bd59d48 | 1144 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 1145 | |
776f02fa | 1146 | BUG_ON(atomic_read(&root->nr_cgrps)); |
d5c419b6 | 1147 | BUG_ON(!list_empty(&cgrp->self.children)); |
f2e85d57 | 1148 | |
f2e85d57 | 1149 | /* Rebind all subsystems back to the default hierarchy */ |
f392e51c | 1150 | rebind_subsystems(&cgrp_dfl_root, root->subsys_mask); |
7717f7ba | 1151 | |
7717f7ba | 1152 | /* |
f2e85d57 TH |
1153 | * Release all the links from cset_links to this hierarchy's |
1154 | * root cgroup | |
7717f7ba | 1155 | */ |
f0d9a5f1 | 1156 | spin_lock_bh(&css_set_lock); |
f2e85d57 TH |
1157 | |
1158 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
1159 | list_del(&link->cset_link); | |
1160 | list_del(&link->cgrp_link); | |
1161 | kfree(link); | |
1162 | } | |
f0d9a5f1 TH |
1163 | |
1164 | spin_unlock_bh(&css_set_lock); | |
f2e85d57 TH |
1165 | |
1166 | if (!list_empty(&root->root_list)) { | |
1167 | list_del(&root->root_list); | |
1168 | cgroup_root_count--; | |
1169 | } | |
1170 | ||
1171 | cgroup_exit_root_id(root); | |
1172 | ||
1173 | mutex_unlock(&cgroup_mutex); | |
f2e85d57 | 1174 | |
2bd59d48 | 1175 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
1176 | cgroup_free_root(root); |
1177 | } | |
1178 | ||
ceb6a081 TH |
1179 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
1180 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
3dd06ffa | 1181 | struct cgroup_root *root) |
7717f7ba | 1182 | { |
7717f7ba PM |
1183 | struct cgroup *res = NULL; |
1184 | ||
96d365e0 | 1185 | lockdep_assert_held(&cgroup_mutex); |
f0d9a5f1 | 1186 | lockdep_assert_held(&css_set_lock); |
96d365e0 | 1187 | |
5abb8855 | 1188 | if (cset == &init_css_set) { |
3dd06ffa | 1189 | res = &root->cgrp; |
7717f7ba | 1190 | } else { |
69d0206c TH |
1191 | struct cgrp_cset_link *link; |
1192 | ||
1193 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 1194 | struct cgroup *c = link->cgrp; |
69d0206c | 1195 | |
7717f7ba PM |
1196 | if (c->root == root) { |
1197 | res = c; | |
1198 | break; | |
1199 | } | |
1200 | } | |
1201 | } | |
96d365e0 | 1202 | |
7717f7ba PM |
1203 | BUG_ON(!res); |
1204 | return res; | |
1205 | } | |
1206 | ||
ddbcc7e8 | 1207 | /* |
ceb6a081 | 1208 | * Return the cgroup for "task" from the given hierarchy. Must be |
f0d9a5f1 | 1209 | * called with cgroup_mutex and css_set_lock held. |
ceb6a081 TH |
1210 | */ |
1211 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
3dd06ffa | 1212 | struct cgroup_root *root) |
ceb6a081 TH |
1213 | { |
1214 | /* | |
1215 | * No need to lock the task - since we hold cgroup_mutex the | |
1216 | * task can't change groups, so the only thing that can happen | |
1217 | * is that it exits and its css is set back to init_css_set. | |
1218 | */ | |
1219 | return cset_cgroup_from_root(task_css_set(task), root); | |
1220 | } | |
1221 | ||
ddbcc7e8 | 1222 | /* |
ddbcc7e8 PM |
1223 | * A task must hold cgroup_mutex to modify cgroups. |
1224 | * | |
1225 | * Any task can increment and decrement the count field without lock. | |
1226 | * So in general, code holding cgroup_mutex can't rely on the count | |
1227 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 1228 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
1229 | * means that no tasks are currently attached, therefore there is no |
1230 | * way a task attached to that cgroup can fork (the other way to | |
1231 | * increment the count). So code holding cgroup_mutex can safely | |
1232 | * assume that if the count is zero, it will stay zero. Similarly, if | |
1233 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
1234 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
1235 | * needs that mutex. | |
1236 | * | |
ddbcc7e8 PM |
1237 | * A cgroup can only be deleted if both its 'count' of using tasks |
1238 | * is zero, and its list of 'children' cgroups is empty. Since all | |
1239 | * tasks in the system use _some_ cgroup, and since there is always at | |
3dd06ffa | 1240 | * least one task in the system (init, pid == 1), therefore, root cgroup |
ddbcc7e8 | 1241 | * always has either children cgroups and/or using tasks. So we don't |
3dd06ffa | 1242 | * need a special hack to ensure that root cgroup cannot be deleted. |
ddbcc7e8 PM |
1243 | * |
1244 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 1245 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
1246 | */ |
1247 | ||
2bd59d48 | 1248 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 1249 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 1250 | |
8d7e6fb0 TH |
1251 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
1252 | char *buf) | |
ddbcc7e8 | 1253 | { |
3e1d2eed TH |
1254 | struct cgroup_subsys *ss = cft->ss; |
1255 | ||
8d7e6fb0 TH |
1256 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
1257 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
1258 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
3e1d2eed TH |
1259 | cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
1260 | cft->name); | |
8d7e6fb0 TH |
1261 | else |
1262 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
1263 | return buf; | |
ddbcc7e8 PM |
1264 | } |
1265 | ||
f2e85d57 TH |
1266 | /** |
1267 | * cgroup_file_mode - deduce file mode of a control file | |
1268 | * @cft: the control file in question | |
1269 | * | |
7dbdb199 | 1270 | * S_IRUGO for read, S_IWUSR for write. |
f2e85d57 TH |
1271 | */ |
1272 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
65dff759 | 1273 | { |
f2e85d57 | 1274 | umode_t mode = 0; |
65dff759 | 1275 | |
f2e85d57 TH |
1276 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) |
1277 | mode |= S_IRUGO; | |
1278 | ||
7dbdb199 TH |
1279 | if (cft->write_u64 || cft->write_s64 || cft->write) { |
1280 | if (cft->flags & CFTYPE_WORLD_WRITABLE) | |
1281 | mode |= S_IWUGO; | |
1282 | else | |
1283 | mode |= S_IWUSR; | |
1284 | } | |
f2e85d57 TH |
1285 | |
1286 | return mode; | |
65dff759 LZ |
1287 | } |
1288 | ||
af0ba678 | 1289 | /** |
8699b776 | 1290 | * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask |
af0ba678 | 1291 | * @cgrp: the target cgroup |
0f060deb | 1292 | * @subtree_control: the new subtree_control mask to consider |
af0ba678 TH |
1293 | * |
1294 | * On the default hierarchy, a subsystem may request other subsystems to be | |
1295 | * enabled together through its ->depends_on mask. In such cases, more | |
1296 | * subsystems than specified in "cgroup.subtree_control" may be enabled. | |
1297 | * | |
0f060deb TH |
1298 | * This function calculates which subsystems need to be enabled if |
1299 | * @subtree_control is to be applied to @cgrp. The returned mask is always | |
1300 | * a superset of @subtree_control and follows the usual hierarchy rules. | |
af0ba678 | 1301 | */ |
6e5c8307 | 1302 | static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control) |
667c2491 | 1303 | { |
6e5c8307 | 1304 | u16 cur_ss_mask = subtree_control; |
af0ba678 TH |
1305 | struct cgroup_subsys *ss; |
1306 | int ssid; | |
1307 | ||
1308 | lockdep_assert_held(&cgroup_mutex); | |
1309 | ||
0f060deb TH |
1310 | if (!cgroup_on_dfl(cgrp)) |
1311 | return cur_ss_mask; | |
af0ba678 TH |
1312 | |
1313 | while (true) { | |
6e5c8307 | 1314 | u16 new_ss_mask = cur_ss_mask; |
af0ba678 | 1315 | |
b4e0eeaf | 1316 | do_each_subsys_mask(ss, ssid, cur_ss_mask) { |
a966a4ed | 1317 | new_ss_mask |= ss->depends_on; |
b4e0eeaf | 1318 | } while_each_subsys_mask(); |
af0ba678 TH |
1319 | |
1320 | /* | |
1321 | * Mask out subsystems which aren't available. This can | |
1322 | * happen only if some depended-upon subsystems were bound | |
1323 | * to non-default hierarchies. | |
1324 | */ | |
5531dc91 | 1325 | new_ss_mask &= cgroup_ss_mask(cgrp); |
af0ba678 TH |
1326 | |
1327 | if (new_ss_mask == cur_ss_mask) | |
1328 | break; | |
1329 | cur_ss_mask = new_ss_mask; | |
1330 | } | |
1331 | ||
0f060deb TH |
1332 | return cur_ss_mask; |
1333 | } | |
1334 | ||
1335 | /** | |
8699b776 | 1336 | * cgroup_refresh_subtree_ss_mask - update subtree_ss_mask |
0f060deb TH |
1337 | * @cgrp: the target cgroup |
1338 | * | |
8699b776 TH |
1339 | * Update @cgrp->subtree_ss_mask according to the current |
1340 | * @cgrp->subtree_control using cgroup_calc_subtree_ss_mask(). | |
0f060deb | 1341 | */ |
8699b776 | 1342 | static void cgroup_refresh_subtree_ss_mask(struct cgroup *cgrp) |
0f060deb | 1343 | { |
8699b776 TH |
1344 | cgrp->subtree_ss_mask = |
1345 | cgroup_calc_subtree_ss_mask(cgrp, cgrp->subtree_control); | |
667c2491 TH |
1346 | } |
1347 | ||
a9746d8d TH |
1348 | /** |
1349 | * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods | |
1350 | * @kn: the kernfs_node being serviced | |
1351 | * | |
1352 | * This helper undoes cgroup_kn_lock_live() and should be invoked before | |
1353 | * the method finishes if locking succeeded. Note that once this function | |
1354 | * returns the cgroup returned by cgroup_kn_lock_live() may become | |
1355 | * inaccessible any time. If the caller intends to continue to access the | |
1356 | * cgroup, it should pin it before invoking this function. | |
1357 | */ | |
1358 | static void cgroup_kn_unlock(struct kernfs_node *kn) | |
ddbcc7e8 | 1359 | { |
a9746d8d TH |
1360 | struct cgroup *cgrp; |
1361 | ||
1362 | if (kernfs_type(kn) == KERNFS_DIR) | |
1363 | cgrp = kn->priv; | |
1364 | else | |
1365 | cgrp = kn->parent->priv; | |
1366 | ||
1367 | mutex_unlock(&cgroup_mutex); | |
a9746d8d TH |
1368 | |
1369 | kernfs_unbreak_active_protection(kn); | |
1370 | cgroup_put(cgrp); | |
ddbcc7e8 PM |
1371 | } |
1372 | ||
a9746d8d TH |
1373 | /** |
1374 | * cgroup_kn_lock_live - locking helper for cgroup kernfs methods | |
1375 | * @kn: the kernfs_node being serviced | |
1376 | * | |
1377 | * This helper is to be used by a cgroup kernfs method currently servicing | |
1378 | * @kn. It breaks the active protection, performs cgroup locking and | |
1379 | * verifies that the associated cgroup is alive. Returns the cgroup if | |
1380 | * alive; otherwise, %NULL. A successful return should be undone by a | |
1381 | * matching cgroup_kn_unlock() invocation. | |
1382 | * | |
1383 | * Any cgroup kernfs method implementation which requires locking the | |
1384 | * associated cgroup should use this helper. It avoids nesting cgroup | |
1385 | * locking under kernfs active protection and allows all kernfs operations | |
1386 | * including self-removal. | |
1387 | */ | |
1388 | static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn) | |
05ef1d7c | 1389 | { |
a9746d8d TH |
1390 | struct cgroup *cgrp; |
1391 | ||
1392 | if (kernfs_type(kn) == KERNFS_DIR) | |
1393 | cgrp = kn->priv; | |
1394 | else | |
1395 | cgrp = kn->parent->priv; | |
05ef1d7c | 1396 | |
2739d3cc | 1397 | /* |
01f6474c | 1398 | * We're gonna grab cgroup_mutex which nests outside kernfs |
a9746d8d TH |
1399 | * active_ref. cgroup liveliness check alone provides enough |
1400 | * protection against removal. Ensure @cgrp stays accessible and | |
1401 | * break the active_ref protection. | |
2739d3cc | 1402 | */ |
aa32362f LZ |
1403 | if (!cgroup_tryget(cgrp)) |
1404 | return NULL; | |
a9746d8d TH |
1405 | kernfs_break_active_protection(kn); |
1406 | ||
2bd59d48 | 1407 | mutex_lock(&cgroup_mutex); |
05ef1d7c | 1408 | |
a9746d8d TH |
1409 | if (!cgroup_is_dead(cgrp)) |
1410 | return cgrp; | |
1411 | ||
1412 | cgroup_kn_unlock(kn); | |
1413 | return NULL; | |
ddbcc7e8 | 1414 | } |
05ef1d7c | 1415 | |
2739d3cc | 1416 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 1417 | { |
2bd59d48 | 1418 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 1419 | |
01f6474c | 1420 | lockdep_assert_held(&cgroup_mutex); |
34c06254 TH |
1421 | |
1422 | if (cft->file_offset) { | |
1423 | struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss); | |
1424 | struct cgroup_file *cfile = (void *)css + cft->file_offset; | |
1425 | ||
1426 | spin_lock_irq(&cgroup_file_kn_lock); | |
1427 | cfile->kn = NULL; | |
1428 | spin_unlock_irq(&cgroup_file_kn_lock); | |
1429 | } | |
1430 | ||
2bd59d48 | 1431 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
1432 | } |
1433 | ||
13af07df | 1434 | /** |
4df8dc90 TH |
1435 | * css_clear_dir - remove subsys files in a cgroup directory |
1436 | * @css: taget css | |
1437 | * @cgrp_override: specify if target cgroup is different from css->cgroup | |
13af07df | 1438 | */ |
4df8dc90 TH |
1439 | static void css_clear_dir(struct cgroup_subsys_state *css, |
1440 | struct cgroup *cgrp_override) | |
05ef1d7c | 1441 | { |
4df8dc90 TH |
1442 | struct cgroup *cgrp = cgrp_override ?: css->cgroup; |
1443 | struct cftype *cfts; | |
05ef1d7c | 1444 | |
88cb04b9 TH |
1445 | if (!(css->flags & CSS_VISIBLE)) |
1446 | return; | |
1447 | ||
1448 | css->flags &= ~CSS_VISIBLE; | |
1449 | ||
4df8dc90 TH |
1450 | list_for_each_entry(cfts, &css->ss->cfts, node) |
1451 | cgroup_addrm_files(css, cgrp, cfts, false); | |
ddbcc7e8 PM |
1452 | } |
1453 | ||
ccdca218 | 1454 | /** |
4df8dc90 TH |
1455 | * css_populate_dir - create subsys files in a cgroup directory |
1456 | * @css: target css | |
1457 | * @cgrp_overried: specify if target cgroup is different from css->cgroup | |
ccdca218 TH |
1458 | * |
1459 | * On failure, no file is added. | |
1460 | */ | |
4df8dc90 TH |
1461 | static int css_populate_dir(struct cgroup_subsys_state *css, |
1462 | struct cgroup *cgrp_override) | |
ccdca218 | 1463 | { |
4df8dc90 TH |
1464 | struct cgroup *cgrp = cgrp_override ?: css->cgroup; |
1465 | struct cftype *cfts, *failed_cfts; | |
1466 | int ret; | |
ccdca218 | 1467 | |
88cb04b9 TH |
1468 | if (css->flags & CSS_VISIBLE) |
1469 | return 0; | |
1470 | ||
4df8dc90 TH |
1471 | if (!css->ss) { |
1472 | if (cgroup_on_dfl(cgrp)) | |
1473 | cfts = cgroup_dfl_base_files; | |
1474 | else | |
1475 | cfts = cgroup_legacy_base_files; | |
ccdca218 | 1476 | |
4df8dc90 TH |
1477 | return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); |
1478 | } | |
ccdca218 | 1479 | |
4df8dc90 TH |
1480 | list_for_each_entry(cfts, &css->ss->cfts, node) { |
1481 | ret = cgroup_addrm_files(css, cgrp, cfts, true); | |
1482 | if (ret < 0) { | |
1483 | failed_cfts = cfts; | |
1484 | goto err; | |
ccdca218 TH |
1485 | } |
1486 | } | |
88cb04b9 TH |
1487 | |
1488 | css->flags |= CSS_VISIBLE; | |
1489 | ||
ccdca218 TH |
1490 | return 0; |
1491 | err: | |
4df8dc90 TH |
1492 | list_for_each_entry(cfts, &css->ss->cfts, node) { |
1493 | if (cfts == failed_cfts) | |
1494 | break; | |
1495 | cgroup_addrm_files(css, cgrp, cfts, false); | |
1496 | } | |
ccdca218 TH |
1497 | return ret; |
1498 | } | |
1499 | ||
6e5c8307 | 1500 | static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask) |
ddbcc7e8 | 1501 | { |
1ada4838 | 1502 | struct cgroup *dcgrp = &dst_root->cgrp; |
30159ec7 | 1503 | struct cgroup_subsys *ss; |
6e5c8307 | 1504 | u16 tmp_ss_mask; |
2d8f243a | 1505 | int ssid, i, ret; |
ddbcc7e8 | 1506 | |
ace2bee8 | 1507 | lockdep_assert_held(&cgroup_mutex); |
ddbcc7e8 | 1508 | |
b4e0eeaf | 1509 | do_each_subsys_mask(ss, ssid, ss_mask) { |
7fd8c565 TH |
1510 | /* if @ss has non-root csses attached to it, can't move */ |
1511 | if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss))) | |
3ed80a62 | 1512 | return -EBUSY; |
1d5be6b2 | 1513 | |
5df36032 | 1514 | /* can't move between two non-dummy roots either */ |
7fd8c565 | 1515 | if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
5df36032 | 1516 | return -EBUSY; |
b4e0eeaf | 1517 | } while_each_subsys_mask(); |
ddbcc7e8 | 1518 | |
5533e011 TH |
1519 | /* skip creating root files on dfl_root for inhibited subsystems */ |
1520 | tmp_ss_mask = ss_mask; | |
1521 | if (dst_root == &cgrp_dfl_root) | |
a7165264 | 1522 | tmp_ss_mask &= ~cgrp_dfl_inhibit_ss_mask; |
5533e011 | 1523 | |
b4e0eeaf | 1524 | do_each_subsys_mask(ss, ssid, tmp_ss_mask) { |
4df8dc90 TH |
1525 | struct cgroup *scgrp = &ss->root->cgrp; |
1526 | int tssid; | |
1527 | ||
1528 | ret = css_populate_dir(cgroup_css(scgrp, ss), dcgrp); | |
1529 | if (!ret) | |
1530 | continue; | |
ddbcc7e8 | 1531 | |
a2dd4247 TH |
1532 | /* |
1533 | * Rebinding back to the default root is not allowed to | |
1534 | * fail. Using both default and non-default roots should | |
1535 | * be rare. Moving subsystems back and forth even more so. | |
1536 | * Just warn about it and continue. | |
1537 | */ | |
4df8dc90 | 1538 | if (dst_root == &cgrp_dfl_root) { |
a7165264 | 1539 | if (cgrp_dfl_visible) { |
6e5c8307 | 1540 | pr_warn("failed to create files (%d) while rebinding 0x%x to default root\n", |
4df8dc90 TH |
1541 | ret, ss_mask); |
1542 | pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); | |
1543 | } | |
1544 | continue; | |
a2dd4247 | 1545 | } |
4df8dc90 | 1546 | |
b4e0eeaf | 1547 | do_each_subsys_mask(ss, tssid, tmp_ss_mask) { |
4df8dc90 TH |
1548 | if (tssid == ssid) |
1549 | break; | |
1550 | css_clear_dir(cgroup_css(scgrp, ss), dcgrp); | |
b4e0eeaf | 1551 | } while_each_subsys_mask(); |
4df8dc90 | 1552 | return ret; |
b4e0eeaf | 1553 | } while_each_subsys_mask(); |
3126121f TH |
1554 | |
1555 | /* | |
1556 | * Nothing can fail from this point on. Remove files for the | |
1557 | * removed subsystems and rebind each subsystem. | |
1558 | */ | |
b4e0eeaf | 1559 | do_each_subsys_mask(ss, ssid, ss_mask) { |
1ada4838 TH |
1560 | struct cgroup_root *src_root = ss->root; |
1561 | struct cgroup *scgrp = &src_root->cgrp; | |
1562 | struct cgroup_subsys_state *css = cgroup_css(scgrp, ss); | |
2d8f243a | 1563 | struct css_set *cset; |
a8a648c4 | 1564 | |
1ada4838 | 1565 | WARN_ON(!css || cgroup_css(dcgrp, ss)); |
a8a648c4 | 1566 | |
4df8dc90 TH |
1567 | css_clear_dir(css, NULL); |
1568 | ||
1ada4838 TH |
1569 | RCU_INIT_POINTER(scgrp->subsys[ssid], NULL); |
1570 | rcu_assign_pointer(dcgrp->subsys[ssid], css); | |
5df36032 | 1571 | ss->root = dst_root; |
1ada4838 | 1572 | css->cgroup = dcgrp; |
73e80ed8 | 1573 | |
f0d9a5f1 | 1574 | spin_lock_bh(&css_set_lock); |
2d8f243a TH |
1575 | hash_for_each(css_set_table, i, cset, hlist) |
1576 | list_move_tail(&cset->e_cset_node[ss->id], | |
1ada4838 | 1577 | &dcgrp->e_csets[ss->id]); |
f0d9a5f1 | 1578 | spin_unlock_bh(&css_set_lock); |
2d8f243a | 1579 | |
f392e51c | 1580 | src_root->subsys_mask &= ~(1 << ssid); |
1ada4838 | 1581 | scgrp->subtree_control &= ~(1 << ssid); |
8699b776 | 1582 | cgroup_refresh_subtree_ss_mask(scgrp); |
f392e51c | 1583 | |
bd53d617 | 1584 | /* default hierarchy doesn't enable controllers by default */ |
f392e51c | 1585 | dst_root->subsys_mask |= 1 << ssid; |
49d1dc4b TH |
1586 | if (dst_root == &cgrp_dfl_root) { |
1587 | static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); | |
1588 | } else { | |
1ada4838 | 1589 | dcgrp->subtree_control |= 1 << ssid; |
8699b776 | 1590 | cgroup_refresh_subtree_ss_mask(dcgrp); |
49d1dc4b | 1591 | static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
667c2491 | 1592 | } |
a8a648c4 | 1593 | |
5df36032 TH |
1594 | if (ss->bind) |
1595 | ss->bind(css); | |
b4e0eeaf | 1596 | } while_each_subsys_mask(); |
ddbcc7e8 | 1597 | |
1ada4838 | 1598 | kernfs_activate(dcgrp->kn); |
ddbcc7e8 PM |
1599 | return 0; |
1600 | } | |
1601 | ||
2bd59d48 TH |
1602 | static int cgroup_show_options(struct seq_file *seq, |
1603 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1604 | { |
3dd06ffa | 1605 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1606 | struct cgroup_subsys *ss; |
b85d2040 | 1607 | int ssid; |
ddbcc7e8 | 1608 | |
d98817d4 TH |
1609 | if (root != &cgrp_dfl_root) |
1610 | for_each_subsys(ss, ssid) | |
1611 | if (root->subsys_mask & (1 << ssid)) | |
61e57c0c | 1612 | seq_show_option(seq, ss->legacy_name, NULL); |
93438629 | 1613 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1614 | seq_puts(seq, ",noprefix"); |
93438629 | 1615 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1616 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1617 | |
1618 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1619 | if (strlen(root->release_agent_path)) |
a068acf2 KC |
1620 | seq_show_option(seq, "release_agent", |
1621 | root->release_agent_path); | |
69e943b7 TH |
1622 | spin_unlock(&release_agent_path_lock); |
1623 | ||
3dd06ffa | 1624 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
97978e6d | 1625 | seq_puts(seq, ",clone_children"); |
c6d57f33 | 1626 | if (strlen(root->name)) |
a068acf2 | 1627 | seq_show_option(seq, "name", root->name); |
ddbcc7e8 PM |
1628 | return 0; |
1629 | } | |
1630 | ||
1631 | struct cgroup_sb_opts { | |
6e5c8307 | 1632 | u16 subsys_mask; |
69dfa00c | 1633 | unsigned int flags; |
81a6a5cd | 1634 | char *release_agent; |
2260e7fc | 1635 | bool cpuset_clone_children; |
c6d57f33 | 1636 | char *name; |
2c6ab6d2 PM |
1637 | /* User explicitly requested empty subsystem */ |
1638 | bool none; | |
ddbcc7e8 PM |
1639 | }; |
1640 | ||
cf5d5941 | 1641 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1642 | { |
32a8cf23 DL |
1643 | char *token, *o = data; |
1644 | bool all_ss = false, one_ss = false; | |
6e5c8307 | 1645 | u16 mask = U16_MAX; |
30159ec7 | 1646 | struct cgroup_subsys *ss; |
7b9a6ba5 | 1647 | int nr_opts = 0; |
30159ec7 | 1648 | int i; |
f9ab5b5b LZ |
1649 | |
1650 | #ifdef CONFIG_CPUSETS | |
6e5c8307 | 1651 | mask = ~((u16)1 << cpuset_cgrp_id); |
f9ab5b5b | 1652 | #endif |
ddbcc7e8 | 1653 | |
c6d57f33 | 1654 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1655 | |
1656 | while ((token = strsep(&o, ",")) != NULL) { | |
7b9a6ba5 TH |
1657 | nr_opts++; |
1658 | ||
ddbcc7e8 PM |
1659 | if (!*token) |
1660 | return -EINVAL; | |
32a8cf23 | 1661 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1662 | /* Explicitly have no subsystems */ |
1663 | opts->none = true; | |
32a8cf23 DL |
1664 | continue; |
1665 | } | |
1666 | if (!strcmp(token, "all")) { | |
1667 | /* Mutually exclusive option 'all' + subsystem name */ | |
1668 | if (one_ss) | |
1669 | return -EINVAL; | |
1670 | all_ss = true; | |
1671 | continue; | |
1672 | } | |
1673 | if (!strcmp(token, "noprefix")) { | |
93438629 | 1674 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1675 | continue; |
1676 | } | |
1677 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1678 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1679 | continue; |
1680 | } | |
03b1cde6 | 1681 | if (!strcmp(token, "xattr")) { |
93438629 | 1682 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1683 | continue; |
1684 | } | |
32a8cf23 | 1685 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1686 | /* Specifying two release agents is forbidden */ |
1687 | if (opts->release_agent) | |
1688 | return -EINVAL; | |
c6d57f33 | 1689 | opts->release_agent = |
e400c285 | 1690 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1691 | if (!opts->release_agent) |
1692 | return -ENOMEM; | |
32a8cf23 DL |
1693 | continue; |
1694 | } | |
1695 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1696 | const char *name = token + 5; |
1697 | /* Can't specify an empty name */ | |
1698 | if (!strlen(name)) | |
1699 | return -EINVAL; | |
1700 | /* Must match [\w.-]+ */ | |
1701 | for (i = 0; i < strlen(name); i++) { | |
1702 | char c = name[i]; | |
1703 | if (isalnum(c)) | |
1704 | continue; | |
1705 | if ((c == '.') || (c == '-') || (c == '_')) | |
1706 | continue; | |
1707 | return -EINVAL; | |
1708 | } | |
1709 | /* Specifying two names is forbidden */ | |
1710 | if (opts->name) | |
1711 | return -EINVAL; | |
1712 | opts->name = kstrndup(name, | |
e400c285 | 1713 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1714 | GFP_KERNEL); |
1715 | if (!opts->name) | |
1716 | return -ENOMEM; | |
32a8cf23 DL |
1717 | |
1718 | continue; | |
1719 | } | |
1720 | ||
30159ec7 | 1721 | for_each_subsys(ss, i) { |
3e1d2eed | 1722 | if (strcmp(token, ss->legacy_name)) |
32a8cf23 | 1723 | continue; |
fc5ed1e9 | 1724 | if (!cgroup_ssid_enabled(i)) |
32a8cf23 | 1725 | continue; |
223ffb29 JW |
1726 | if (cgroup_ssid_no_v1(i)) |
1727 | continue; | |
32a8cf23 DL |
1728 | |
1729 | /* Mutually exclusive option 'all' + subsystem name */ | |
1730 | if (all_ss) | |
1731 | return -EINVAL; | |
69dfa00c | 1732 | opts->subsys_mask |= (1 << i); |
32a8cf23 DL |
1733 | one_ss = true; |
1734 | ||
1735 | break; | |
1736 | } | |
1737 | if (i == CGROUP_SUBSYS_COUNT) | |
1738 | return -ENOENT; | |
1739 | } | |
1740 | ||
7b9a6ba5 TH |
1741 | /* |
1742 | * If the 'all' option was specified select all the subsystems, | |
1743 | * otherwise if 'none', 'name=' and a subsystem name options were | |
1744 | * not specified, let's default to 'all' | |
1745 | */ | |
1746 | if (all_ss || (!one_ss && !opts->none && !opts->name)) | |
1747 | for_each_subsys(ss, i) | |
223ffb29 | 1748 | if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i)) |
7b9a6ba5 TH |
1749 | opts->subsys_mask |= (1 << i); |
1750 | ||
1751 | /* | |
1752 | * We either have to specify by name or by subsystems. (So all | |
1753 | * empty hierarchies must have a name). | |
1754 | */ | |
1755 | if (!opts->subsys_mask && !opts->name) | |
1756 | return -EINVAL; | |
1757 | ||
f9ab5b5b LZ |
1758 | /* |
1759 | * Option noprefix was introduced just for backward compatibility | |
1760 | * with the old cpuset, so we allow noprefix only if mounting just | |
1761 | * the cpuset subsystem. | |
1762 | */ | |
93438629 | 1763 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1764 | return -EINVAL; |
1765 | ||
2c6ab6d2 | 1766 | /* Can't specify "none" and some subsystems */ |
a1a71b45 | 1767 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1768 | return -EINVAL; |
1769 | ||
ddbcc7e8 PM |
1770 | return 0; |
1771 | } | |
1772 | ||
2bd59d48 | 1773 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1774 | { |
1775 | int ret = 0; | |
3dd06ffa | 1776 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1777 | struct cgroup_sb_opts opts; |
6e5c8307 | 1778 | u16 added_mask, removed_mask; |
ddbcc7e8 | 1779 | |
aa6ec29b TH |
1780 | if (root == &cgrp_dfl_root) { |
1781 | pr_err("remount is not allowed\n"); | |
873fe09e TH |
1782 | return -EINVAL; |
1783 | } | |
1784 | ||
ddbcc7e8 PM |
1785 | mutex_lock(&cgroup_mutex); |
1786 | ||
1787 | /* See what subsystems are wanted */ | |
1788 | ret = parse_cgroupfs_options(data, &opts); | |
1789 | if (ret) | |
1790 | goto out_unlock; | |
1791 | ||
f392e51c | 1792 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
ed3d261b | 1793 | pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
a2a1f9ea | 1794 | task_tgid_nr(current), current->comm); |
8b5a5a9d | 1795 | |
f392e51c TH |
1796 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1797 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1798 | |
cf5d5941 | 1799 | /* Don't allow flags or name to change at remount */ |
7450e90b | 1800 | if ((opts.flags ^ root->flags) || |
cf5d5941 | 1801 | (opts.name && strcmp(opts.name, root->name))) { |
69dfa00c | 1802 | pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", |
7450e90b | 1803 | opts.flags, opts.name ?: "", root->flags, root->name); |
c6d57f33 PM |
1804 | ret = -EINVAL; |
1805 | goto out_unlock; | |
1806 | } | |
1807 | ||
f172e67c | 1808 | /* remounting is not allowed for populated hierarchies */ |
d5c419b6 | 1809 | if (!list_empty(&root->cgrp.self.children)) { |
f172e67c | 1810 | ret = -EBUSY; |
0670e08b | 1811 | goto out_unlock; |
cf5d5941 | 1812 | } |
ddbcc7e8 | 1813 | |
5df36032 | 1814 | ret = rebind_subsystems(root, added_mask); |
3126121f | 1815 | if (ret) |
0670e08b | 1816 | goto out_unlock; |
ddbcc7e8 | 1817 | |
3dd06ffa | 1818 | rebind_subsystems(&cgrp_dfl_root, removed_mask); |
5df36032 | 1819 | |
69e943b7 TH |
1820 | if (opts.release_agent) { |
1821 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1822 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1823 | spin_unlock(&release_agent_path_lock); |
1824 | } | |
ddbcc7e8 | 1825 | out_unlock: |
66bdc9cf | 1826 | kfree(opts.release_agent); |
c6d57f33 | 1827 | kfree(opts.name); |
ddbcc7e8 | 1828 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
1829 | return ret; |
1830 | } | |
1831 | ||
afeb0f9f TH |
1832 | /* |
1833 | * To reduce the fork() overhead for systems that are not actually using | |
1834 | * their cgroups capability, we don't maintain the lists running through | |
1835 | * each css_set to its tasks until we see the list actually used - in other | |
1836 | * words after the first mount. | |
1837 | */ | |
1838 | static bool use_task_css_set_links __read_mostly; | |
1839 | ||
1840 | static void cgroup_enable_task_cg_lists(void) | |
1841 | { | |
1842 | struct task_struct *p, *g; | |
1843 | ||
f0d9a5f1 | 1844 | spin_lock_bh(&css_set_lock); |
afeb0f9f TH |
1845 | |
1846 | if (use_task_css_set_links) | |
1847 | goto out_unlock; | |
1848 | ||
1849 | use_task_css_set_links = true; | |
1850 | ||
1851 | /* | |
1852 | * We need tasklist_lock because RCU is not safe against | |
1853 | * while_each_thread(). Besides, a forking task that has passed | |
1854 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1855 | * is not guaranteed to have its child immediately visible in the | |
1856 | * tasklist if we walk through it with RCU. | |
1857 | */ | |
1858 | read_lock(&tasklist_lock); | |
1859 | do_each_thread(g, p) { | |
afeb0f9f TH |
1860 | WARN_ON_ONCE(!list_empty(&p->cg_list) || |
1861 | task_css_set(p) != &init_css_set); | |
1862 | ||
1863 | /* | |
1864 | * We should check if the process is exiting, otherwise | |
1865 | * it will race with cgroup_exit() in that the list | |
1866 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1867 | * Do it while holding siglock so that we don't end up |
1868 | * racing against cgroup_exit(). | |
afeb0f9f | 1869 | */ |
f153ad11 | 1870 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1871 | if (!(p->flags & PF_EXITING)) { |
1872 | struct css_set *cset = task_css_set(p); | |
1873 | ||
0de0942d TH |
1874 | if (!css_set_populated(cset)) |
1875 | css_set_update_populated(cset, true); | |
389b9c1b | 1876 | list_add_tail(&p->cg_list, &cset->tasks); |
eaf797ab TH |
1877 | get_css_set(cset); |
1878 | } | |
f153ad11 | 1879 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1880 | } while_each_thread(g, p); |
1881 | read_unlock(&tasklist_lock); | |
1882 | out_unlock: | |
f0d9a5f1 | 1883 | spin_unlock_bh(&css_set_lock); |
afeb0f9f | 1884 | } |
ddbcc7e8 | 1885 | |
cc31edce PM |
1886 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1887 | { | |
2d8f243a TH |
1888 | struct cgroup_subsys *ss; |
1889 | int ssid; | |
1890 | ||
d5c419b6 TH |
1891 | INIT_LIST_HEAD(&cgrp->self.sibling); |
1892 | INIT_LIST_HEAD(&cgrp->self.children); | |
69d0206c | 1893 | INIT_LIST_HEAD(&cgrp->cset_links); |
72a8cb30 BB |
1894 | INIT_LIST_HEAD(&cgrp->pidlists); |
1895 | mutex_init(&cgrp->pidlist_mutex); | |
9d800df1 | 1896 | cgrp->self.cgroup = cgrp; |
184faf32 | 1897 | cgrp->self.flags |= CSS_ONLINE; |
2d8f243a TH |
1898 | |
1899 | for_each_subsys(ss, ssid) | |
1900 | INIT_LIST_HEAD(&cgrp->e_csets[ssid]); | |
f8f22e53 TH |
1901 | |
1902 | init_waitqueue_head(&cgrp->offline_waitq); | |
971ff493 | 1903 | INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent); |
cc31edce | 1904 | } |
c6d57f33 | 1905 | |
3dd06ffa | 1906 | static void init_cgroup_root(struct cgroup_root *root, |
172a2c06 | 1907 | struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1908 | { |
3dd06ffa | 1909 | struct cgroup *cgrp = &root->cgrp; |
b0ca5a84 | 1910 | |
ddbcc7e8 | 1911 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1912 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1913 | cgrp->root = root; |
cc31edce | 1914 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1915 | idr_init(&root->cgroup_idr); |
c6d57f33 | 1916 | |
c6d57f33 PM |
1917 | root->flags = opts->flags; |
1918 | if (opts->release_agent) | |
1919 | strcpy(root->release_agent_path, opts->release_agent); | |
1920 | if (opts->name) | |
1921 | strcpy(root->name, opts->name); | |
2260e7fc | 1922 | if (opts->cpuset_clone_children) |
3dd06ffa | 1923 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
c6d57f33 PM |
1924 | } |
1925 | ||
6e5c8307 | 1926 | static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) |
2c6ab6d2 | 1927 | { |
d427dfeb | 1928 | LIST_HEAD(tmp_links); |
3dd06ffa | 1929 | struct cgroup *root_cgrp = &root->cgrp; |
d427dfeb | 1930 | struct css_set *cset; |
d427dfeb | 1931 | int i, ret; |
2c6ab6d2 | 1932 | |
d427dfeb | 1933 | lockdep_assert_held(&cgroup_mutex); |
c6d57f33 | 1934 | |
cf780b7d | 1935 | ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
d427dfeb | 1936 | if (ret < 0) |
2bd59d48 | 1937 | goto out; |
d427dfeb | 1938 | root_cgrp->id = ret; |
b11cfb58 | 1939 | root_cgrp->ancestor_ids[0] = ret; |
c6d57f33 | 1940 | |
2aad2a86 TH |
1941 | ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0, |
1942 | GFP_KERNEL); | |
9d755d33 TH |
1943 | if (ret) |
1944 | goto out; | |
1945 | ||
d427dfeb | 1946 | /* |
f0d9a5f1 | 1947 | * We're accessing css_set_count without locking css_set_lock here, |
d427dfeb TH |
1948 | * but that's OK - it can only be increased by someone holding |
1949 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1950 | * have some link structures left over | |
1951 | */ | |
1952 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1953 | if (ret) | |
9d755d33 | 1954 | goto cancel_ref; |
ddbcc7e8 | 1955 | |
985ed670 | 1956 | ret = cgroup_init_root_id(root); |
ddbcc7e8 | 1957 | if (ret) |
9d755d33 | 1958 | goto cancel_ref; |
ddbcc7e8 | 1959 | |
2bd59d48 TH |
1960 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1961 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1962 | root_cgrp); | |
1963 | if (IS_ERR(root->kf_root)) { | |
1964 | ret = PTR_ERR(root->kf_root); | |
1965 | goto exit_root_id; | |
1966 | } | |
1967 | root_cgrp->kn = root->kf_root->kn; | |
ddbcc7e8 | 1968 | |
4df8dc90 | 1969 | ret = css_populate_dir(&root_cgrp->self, NULL); |
d427dfeb | 1970 | if (ret) |
2bd59d48 | 1971 | goto destroy_root; |
ddbcc7e8 | 1972 | |
5df36032 | 1973 | ret = rebind_subsystems(root, ss_mask); |
d427dfeb | 1974 | if (ret) |
2bd59d48 | 1975 | goto destroy_root; |
ddbcc7e8 | 1976 | |
d427dfeb TH |
1977 | /* |
1978 | * There must be no failure case after here, since rebinding takes | |
1979 | * care of subsystems' refcounts, which are explicitly dropped in | |
1980 | * the failure exit path. | |
1981 | */ | |
1982 | list_add(&root->root_list, &cgroup_roots); | |
1983 | cgroup_root_count++; | |
0df6a63f | 1984 | |
d427dfeb | 1985 | /* |
3dd06ffa | 1986 | * Link the root cgroup in this hierarchy into all the css_set |
d427dfeb TH |
1987 | * objects. |
1988 | */ | |
f0d9a5f1 | 1989 | spin_lock_bh(&css_set_lock); |
0de0942d | 1990 | hash_for_each(css_set_table, i, cset, hlist) { |
d427dfeb | 1991 | link_css_set(&tmp_links, cset, root_cgrp); |
0de0942d TH |
1992 | if (css_set_populated(cset)) |
1993 | cgroup_update_populated(root_cgrp, true); | |
1994 | } | |
f0d9a5f1 | 1995 | spin_unlock_bh(&css_set_lock); |
ddbcc7e8 | 1996 | |
d5c419b6 | 1997 | BUG_ON(!list_empty(&root_cgrp->self.children)); |
3c9c825b | 1998 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
ddbcc7e8 | 1999 | |
2bd59d48 | 2000 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 2001 | ret = 0; |
2bd59d48 | 2002 | goto out; |
d427dfeb | 2003 | |
2bd59d48 TH |
2004 | destroy_root: |
2005 | kernfs_destroy_root(root->kf_root); | |
2006 | root->kf_root = NULL; | |
2007 | exit_root_id: | |
d427dfeb | 2008 | cgroup_exit_root_id(root); |
9d755d33 | 2009 | cancel_ref: |
9a1049da | 2010 | percpu_ref_exit(&root_cgrp->self.refcnt); |
2bd59d48 | 2011 | out: |
d427dfeb TH |
2012 | free_cgrp_cset_links(&tmp_links); |
2013 | return ret; | |
ddbcc7e8 PM |
2014 | } |
2015 | ||
f7e83571 | 2016 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 2017 | int flags, const char *unused_dev_name, |
f7e83571 | 2018 | void *data) |
ddbcc7e8 | 2019 | { |
67e9c74b | 2020 | bool is_v2 = fs_type == &cgroup2_fs_type; |
3a32bd72 | 2021 | struct super_block *pinned_sb = NULL; |
970317aa | 2022 | struct cgroup_subsys *ss; |
3dd06ffa | 2023 | struct cgroup_root *root; |
ddbcc7e8 | 2024 | struct cgroup_sb_opts opts; |
2bd59d48 | 2025 | struct dentry *dentry; |
8e30e2b8 | 2026 | int ret; |
970317aa | 2027 | int i; |
c6b3d5bc | 2028 | bool new_sb; |
ddbcc7e8 | 2029 | |
56fde9e0 TH |
2030 | /* |
2031 | * The first time anyone tries to mount a cgroup, enable the list | |
2032 | * linking each css_set to its tasks and fix up all existing tasks. | |
2033 | */ | |
2034 | if (!use_task_css_set_links) | |
2035 | cgroup_enable_task_cg_lists(); | |
e37a06f1 | 2036 | |
67e9c74b TH |
2037 | if (is_v2) { |
2038 | if (data) { | |
2039 | pr_err("cgroup2: unknown option \"%s\"\n", (char *)data); | |
2040 | return ERR_PTR(-EINVAL); | |
2041 | } | |
a7165264 | 2042 | cgrp_dfl_visible = true; |
67e9c74b TH |
2043 | root = &cgrp_dfl_root; |
2044 | cgroup_get(&root->cgrp); | |
2045 | goto out_mount; | |
2046 | } | |
2047 | ||
aae8aab4 | 2048 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
2049 | |
2050 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 2051 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 2052 | if (ret) |
8e30e2b8 | 2053 | goto out_unlock; |
a015edd2 | 2054 | |
970317aa LZ |
2055 | /* |
2056 | * Destruction of cgroup root is asynchronous, so subsystems may | |
2057 | * still be dying after the previous unmount. Let's drain the | |
2058 | * dying subsystems. We just need to ensure that the ones | |
2059 | * unmounted previously finish dying and don't care about new ones | |
2060 | * starting. Testing ref liveliness is good enough. | |
2061 | */ | |
2062 | for_each_subsys(ss, i) { | |
2063 | if (!(opts.subsys_mask & (1 << i)) || | |
2064 | ss->root == &cgrp_dfl_root) | |
2065 | continue; | |
2066 | ||
2067 | if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) { | |
2068 | mutex_unlock(&cgroup_mutex); | |
2069 | msleep(10); | |
2070 | ret = restart_syscall(); | |
2071 | goto out_free; | |
2072 | } | |
2073 | cgroup_put(&ss->root->cgrp); | |
2074 | } | |
2075 | ||
985ed670 | 2076 | for_each_root(root) { |
2bd59d48 | 2077 | bool name_match = false; |
3126121f | 2078 | |
3dd06ffa | 2079 | if (root == &cgrp_dfl_root) |
985ed670 | 2080 | continue; |
3126121f | 2081 | |
cf5d5941 | 2082 | /* |
2bd59d48 TH |
2083 | * If we asked for a name then it must match. Also, if |
2084 | * name matches but sybsys_mask doesn't, we should fail. | |
2085 | * Remember whether name matched. | |
cf5d5941 | 2086 | */ |
2bd59d48 TH |
2087 | if (opts.name) { |
2088 | if (strcmp(opts.name, root->name)) | |
2089 | continue; | |
2090 | name_match = true; | |
2091 | } | |
ddbcc7e8 | 2092 | |
c6d57f33 | 2093 | /* |
2bd59d48 TH |
2094 | * If we asked for subsystems (or explicitly for no |
2095 | * subsystems) then they must match. | |
c6d57f33 | 2096 | */ |
2bd59d48 | 2097 | if ((opts.subsys_mask || opts.none) && |
f392e51c | 2098 | (opts.subsys_mask != root->subsys_mask)) { |
2bd59d48 TH |
2099 | if (!name_match) |
2100 | continue; | |
2101 | ret = -EBUSY; | |
2102 | goto out_unlock; | |
2103 | } | |
873fe09e | 2104 | |
7b9a6ba5 TH |
2105 | if (root->flags ^ opts.flags) |
2106 | pr_warn("new mount options do not match the existing superblock, will be ignored\n"); | |
ddbcc7e8 | 2107 | |
776f02fa | 2108 | /* |
3a32bd72 LZ |
2109 | * We want to reuse @root whose lifetime is governed by its |
2110 | * ->cgrp. Let's check whether @root is alive and keep it | |
2111 | * that way. As cgroup_kill_sb() can happen anytime, we | |
2112 | * want to block it by pinning the sb so that @root doesn't | |
2113 | * get killed before mount is complete. | |
2114 | * | |
2115 | * With the sb pinned, tryget_live can reliably indicate | |
2116 | * whether @root can be reused. If it's being killed, | |
2117 | * drain it. We can use wait_queue for the wait but this | |
2118 | * path is super cold. Let's just sleep a bit and retry. | |
776f02fa | 2119 | */ |
3a32bd72 LZ |
2120 | pinned_sb = kernfs_pin_sb(root->kf_root, NULL); |
2121 | if (IS_ERR(pinned_sb) || | |
2122 | !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { | |
776f02fa | 2123 | mutex_unlock(&cgroup_mutex); |
3a32bd72 LZ |
2124 | if (!IS_ERR_OR_NULL(pinned_sb)) |
2125 | deactivate_super(pinned_sb); | |
776f02fa | 2126 | msleep(10); |
a015edd2 TH |
2127 | ret = restart_syscall(); |
2128 | goto out_free; | |
776f02fa | 2129 | } |
ddbcc7e8 | 2130 | |
776f02fa | 2131 | ret = 0; |
2bd59d48 | 2132 | goto out_unlock; |
ddbcc7e8 | 2133 | } |
ddbcc7e8 | 2134 | |
817929ec | 2135 | /* |
172a2c06 TH |
2136 | * No such thing, create a new one. name= matching without subsys |
2137 | * specification is allowed for already existing hierarchies but we | |
2138 | * can't create new one without subsys specification. | |
817929ec | 2139 | */ |
172a2c06 TH |
2140 | if (!opts.subsys_mask && !opts.none) { |
2141 | ret = -EINVAL; | |
2142 | goto out_unlock; | |
817929ec | 2143 | } |
817929ec | 2144 | |
172a2c06 TH |
2145 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
2146 | if (!root) { | |
2147 | ret = -ENOMEM; | |
2bd59d48 | 2148 | goto out_unlock; |
839ec545 | 2149 | } |
e5f6a860 | 2150 | |
172a2c06 TH |
2151 | init_cgroup_root(root, &opts); |
2152 | ||
35585573 | 2153 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
2154 | if (ret) |
2155 | cgroup_free_root(root); | |
fa3ca07e | 2156 | |
8e30e2b8 | 2157 | out_unlock: |
ddbcc7e8 | 2158 | mutex_unlock(&cgroup_mutex); |
a015edd2 | 2159 | out_free: |
c6d57f33 PM |
2160 | kfree(opts.release_agent); |
2161 | kfree(opts.name); | |
03b1cde6 | 2162 | |
2bd59d48 | 2163 | if (ret) |
8e30e2b8 | 2164 | return ERR_PTR(ret); |
67e9c74b | 2165 | out_mount: |
c9482a5b | 2166 | dentry = kernfs_mount(fs_type, flags, root->kf_root, |
67e9c74b TH |
2167 | is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC, |
2168 | &new_sb); | |
c6b3d5bc | 2169 | if (IS_ERR(dentry) || !new_sb) |
3dd06ffa | 2170 | cgroup_put(&root->cgrp); |
3a32bd72 LZ |
2171 | |
2172 | /* | |
2173 | * If @pinned_sb, we're reusing an existing root and holding an | |
2174 | * extra ref on its sb. Mount is complete. Put the extra ref. | |
2175 | */ | |
2176 | if (pinned_sb) { | |
2177 | WARN_ON(new_sb); | |
2178 | deactivate_super(pinned_sb); | |
2179 | } | |
2180 | ||
2bd59d48 TH |
2181 | return dentry; |
2182 | } | |
2183 | ||
2184 | static void cgroup_kill_sb(struct super_block *sb) | |
2185 | { | |
2186 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
3dd06ffa | 2187 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
2bd59d48 | 2188 | |
9d755d33 TH |
2189 | /* |
2190 | * If @root doesn't have any mounts or children, start killing it. | |
2191 | * This prevents new mounts by disabling percpu_ref_tryget_live(). | |
2192 | * cgroup_mount() may wait for @root's release. | |
1f779fb2 LZ |
2193 | * |
2194 | * And don't kill the default root. | |
9d755d33 | 2195 | */ |
3c606d35 | 2196 | if (!list_empty(&root->cgrp.self.children) || |
1f779fb2 | 2197 | root == &cgrp_dfl_root) |
9d755d33 TH |
2198 | cgroup_put(&root->cgrp); |
2199 | else | |
2200 | percpu_ref_kill(&root->cgrp.self.refcnt); | |
2201 | ||
2bd59d48 | 2202 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
2203 | } |
2204 | ||
2205 | static struct file_system_type cgroup_fs_type = { | |
2206 | .name = "cgroup", | |
f7e83571 | 2207 | .mount = cgroup_mount, |
ddbcc7e8 PM |
2208 | .kill_sb = cgroup_kill_sb, |
2209 | }; | |
2210 | ||
67e9c74b TH |
2211 | static struct file_system_type cgroup2_fs_type = { |
2212 | .name = "cgroup2", | |
2213 | .mount = cgroup_mount, | |
2214 | .kill_sb = cgroup_kill_sb, | |
2215 | }; | |
2216 | ||
857a2beb | 2217 | /** |
913ffdb5 | 2218 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 2219 | * @task: target task |
857a2beb TH |
2220 | * @buf: the buffer to write the path into |
2221 | * @buflen: the length of the buffer | |
2222 | * | |
913ffdb5 TH |
2223 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
2224 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
2225 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
2226 | * cgroup controller callbacks. | |
2227 | * | |
e61734c5 | 2228 | * Return value is the same as kernfs_path(). |
857a2beb | 2229 | */ |
e61734c5 | 2230 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb | 2231 | { |
3dd06ffa | 2232 | struct cgroup_root *root; |
913ffdb5 | 2233 | struct cgroup *cgrp; |
e61734c5 TH |
2234 | int hierarchy_id = 1; |
2235 | char *path = NULL; | |
857a2beb TH |
2236 | |
2237 | mutex_lock(&cgroup_mutex); | |
f0d9a5f1 | 2238 | spin_lock_bh(&css_set_lock); |
857a2beb | 2239 | |
913ffdb5 TH |
2240 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
2241 | ||
857a2beb TH |
2242 | if (root) { |
2243 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 2244 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
2245 | } else { |
2246 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
2247 | if (strlcpy(buf, "/", buflen) < buflen) |
2248 | path = buf; | |
857a2beb TH |
2249 | } |
2250 | ||
f0d9a5f1 | 2251 | spin_unlock_bh(&css_set_lock); |
857a2beb | 2252 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 2253 | return path; |
857a2beb | 2254 | } |
913ffdb5 | 2255 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 2256 | |
b3dc094e | 2257 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 2258 | struct cgroup_taskset { |
b3dc094e TH |
2259 | /* the src and dst cset list running through cset->mg_node */ |
2260 | struct list_head src_csets; | |
2261 | struct list_head dst_csets; | |
2262 | ||
1f7dd3e5 TH |
2263 | /* the subsys currently being processed */ |
2264 | int ssid; | |
2265 | ||
b3dc094e TH |
2266 | /* |
2267 | * Fields for cgroup_taskset_*() iteration. | |
2268 | * | |
2269 | * Before migration is committed, the target migration tasks are on | |
2270 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
2271 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
2272 | * or ->dst_csets depending on whether migration is committed. | |
2273 | * | |
2274 | * ->cur_csets and ->cur_task point to the current task position | |
2275 | * during iteration. | |
2276 | */ | |
2277 | struct list_head *csets; | |
2278 | struct css_set *cur_cset; | |
2279 | struct task_struct *cur_task; | |
2f7ee569 TH |
2280 | }; |
2281 | ||
adaae5dc TH |
2282 | #define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \ |
2283 | .src_csets = LIST_HEAD_INIT(tset.src_csets), \ | |
2284 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \ | |
2285 | .csets = &tset.src_csets, \ | |
2286 | } | |
2287 | ||
2288 | /** | |
2289 | * cgroup_taskset_add - try to add a migration target task to a taskset | |
2290 | * @task: target task | |
2291 | * @tset: target taskset | |
2292 | * | |
2293 | * Add @task, which is a migration target, to @tset. This function becomes | |
2294 | * noop if @task doesn't need to be migrated. @task's css_set should have | |
2295 | * been added as a migration source and @task->cg_list will be moved from | |
2296 | * the css_set's tasks list to mg_tasks one. | |
2297 | */ | |
2298 | static void cgroup_taskset_add(struct task_struct *task, | |
2299 | struct cgroup_taskset *tset) | |
2300 | { | |
2301 | struct css_set *cset; | |
2302 | ||
f0d9a5f1 | 2303 | lockdep_assert_held(&css_set_lock); |
adaae5dc TH |
2304 | |
2305 | /* @task either already exited or can't exit until the end */ | |
2306 | if (task->flags & PF_EXITING) | |
2307 | return; | |
2308 | ||
2309 | /* leave @task alone if post_fork() hasn't linked it yet */ | |
2310 | if (list_empty(&task->cg_list)) | |
2311 | return; | |
2312 | ||
2313 | cset = task_css_set(task); | |
2314 | if (!cset->mg_src_cgrp) | |
2315 | return; | |
2316 | ||
2317 | list_move_tail(&task->cg_list, &cset->mg_tasks); | |
2318 | if (list_empty(&cset->mg_node)) | |
2319 | list_add_tail(&cset->mg_node, &tset->src_csets); | |
2320 | if (list_empty(&cset->mg_dst_cset->mg_node)) | |
2321 | list_move_tail(&cset->mg_dst_cset->mg_node, | |
2322 | &tset->dst_csets); | |
2323 | } | |
2324 | ||
2f7ee569 TH |
2325 | /** |
2326 | * cgroup_taskset_first - reset taskset and return the first task | |
2327 | * @tset: taskset of interest | |
1f7dd3e5 | 2328 | * @dst_cssp: output variable for the destination css |
2f7ee569 TH |
2329 | * |
2330 | * @tset iteration is initialized and the first task is returned. | |
2331 | */ | |
1f7dd3e5 TH |
2332 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset, |
2333 | struct cgroup_subsys_state **dst_cssp) | |
2f7ee569 | 2334 | { |
b3dc094e TH |
2335 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
2336 | tset->cur_task = NULL; | |
2337 | ||
1f7dd3e5 | 2338 | return cgroup_taskset_next(tset, dst_cssp); |
2f7ee569 | 2339 | } |
2f7ee569 TH |
2340 | |
2341 | /** | |
2342 | * cgroup_taskset_next - iterate to the next task in taskset | |
2343 | * @tset: taskset of interest | |
1f7dd3e5 | 2344 | * @dst_cssp: output variable for the destination css |
2f7ee569 TH |
2345 | * |
2346 | * Return the next task in @tset. Iteration must have been initialized | |
2347 | * with cgroup_taskset_first(). | |
2348 | */ | |
1f7dd3e5 TH |
2349 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset, |
2350 | struct cgroup_subsys_state **dst_cssp) | |
2f7ee569 | 2351 | { |
b3dc094e TH |
2352 | struct css_set *cset = tset->cur_cset; |
2353 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 2354 | |
b3dc094e TH |
2355 | while (&cset->mg_node != tset->csets) { |
2356 | if (!task) | |
2357 | task = list_first_entry(&cset->mg_tasks, | |
2358 | struct task_struct, cg_list); | |
2359 | else | |
2360 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 2361 | |
b3dc094e TH |
2362 | if (&task->cg_list != &cset->mg_tasks) { |
2363 | tset->cur_cset = cset; | |
2364 | tset->cur_task = task; | |
1f7dd3e5 TH |
2365 | |
2366 | /* | |
2367 | * This function may be called both before and | |
2368 | * after cgroup_taskset_migrate(). The two cases | |
2369 | * can be distinguished by looking at whether @cset | |
2370 | * has its ->mg_dst_cset set. | |
2371 | */ | |
2372 | if (cset->mg_dst_cset) | |
2373 | *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid]; | |
2374 | else | |
2375 | *dst_cssp = cset->subsys[tset->ssid]; | |
2376 | ||
b3dc094e TH |
2377 | return task; |
2378 | } | |
2f7ee569 | 2379 | |
b3dc094e TH |
2380 | cset = list_next_entry(cset, mg_node); |
2381 | task = NULL; | |
2382 | } | |
2f7ee569 | 2383 | |
b3dc094e | 2384 | return NULL; |
2f7ee569 | 2385 | } |
2f7ee569 | 2386 | |
adaae5dc TH |
2387 | /** |
2388 | * cgroup_taskset_migrate - migrate a taskset to a cgroup | |
2389 | * @tset: taget taskset | |
2390 | * @dst_cgrp: destination cgroup | |
2391 | * | |
2392 | * Migrate tasks in @tset to @dst_cgrp. This function fails iff one of the | |
2393 | * ->can_attach callbacks fails and guarantees that either all or none of | |
2394 | * the tasks in @tset are migrated. @tset is consumed regardless of | |
2395 | * success. | |
2396 | */ | |
2397 | static int cgroup_taskset_migrate(struct cgroup_taskset *tset, | |
2398 | struct cgroup *dst_cgrp) | |
2399 | { | |
2400 | struct cgroup_subsys_state *css, *failed_css = NULL; | |
2401 | struct task_struct *task, *tmp_task; | |
2402 | struct css_set *cset, *tmp_cset; | |
2403 | int i, ret; | |
2404 | ||
2405 | /* methods shouldn't be called if no task is actually migrating */ | |
2406 | if (list_empty(&tset->src_csets)) | |
2407 | return 0; | |
2408 | ||
2409 | /* check that we can legitimately attach to the cgroup */ | |
2410 | for_each_e_css(css, i, dst_cgrp) { | |
2411 | if (css->ss->can_attach) { | |
1f7dd3e5 TH |
2412 | tset->ssid = i; |
2413 | ret = css->ss->can_attach(tset); | |
adaae5dc TH |
2414 | if (ret) { |
2415 | failed_css = css; | |
2416 | goto out_cancel_attach; | |
2417 | } | |
2418 | } | |
2419 | } | |
2420 | ||
2421 | /* | |
2422 | * Now that we're guaranteed success, proceed to move all tasks to | |
2423 | * the new cgroup. There are no failure cases after here, so this | |
2424 | * is the commit point. | |
2425 | */ | |
f0d9a5f1 | 2426 | spin_lock_bh(&css_set_lock); |
adaae5dc | 2427 | list_for_each_entry(cset, &tset->src_csets, mg_node) { |
f6d7d049 TH |
2428 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) { |
2429 | struct css_set *from_cset = task_css_set(task); | |
2430 | struct css_set *to_cset = cset->mg_dst_cset; | |
2431 | ||
2432 | get_css_set(to_cset); | |
2433 | css_set_move_task(task, from_cset, to_cset, true); | |
2434 | put_css_set_locked(from_cset); | |
2435 | } | |
adaae5dc | 2436 | } |
f0d9a5f1 | 2437 | spin_unlock_bh(&css_set_lock); |
adaae5dc TH |
2438 | |
2439 | /* | |
2440 | * Migration is committed, all target tasks are now on dst_csets. | |
2441 | * Nothing is sensitive to fork() after this point. Notify | |
2442 | * controllers that migration is complete. | |
2443 | */ | |
2444 | tset->csets = &tset->dst_csets; | |
2445 | ||
1f7dd3e5 TH |
2446 | for_each_e_css(css, i, dst_cgrp) { |
2447 | if (css->ss->attach) { | |
2448 | tset->ssid = i; | |
2449 | css->ss->attach(tset); | |
2450 | } | |
2451 | } | |
adaae5dc TH |
2452 | |
2453 | ret = 0; | |
2454 | goto out_release_tset; | |
2455 | ||
2456 | out_cancel_attach: | |
2457 | for_each_e_css(css, i, dst_cgrp) { | |
2458 | if (css == failed_css) | |
2459 | break; | |
1f7dd3e5 TH |
2460 | if (css->ss->cancel_attach) { |
2461 | tset->ssid = i; | |
2462 | css->ss->cancel_attach(tset); | |
2463 | } | |
adaae5dc TH |
2464 | } |
2465 | out_release_tset: | |
f0d9a5f1 | 2466 | spin_lock_bh(&css_set_lock); |
adaae5dc TH |
2467 | list_splice_init(&tset->dst_csets, &tset->src_csets); |
2468 | list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) { | |
2469 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks); | |
2470 | list_del_init(&cset->mg_node); | |
2471 | } | |
f0d9a5f1 | 2472 | spin_unlock_bh(&css_set_lock); |
adaae5dc TH |
2473 | return ret; |
2474 | } | |
2475 | ||
a043e3b2 | 2476 | /** |
1958d2d5 TH |
2477 | * cgroup_migrate_finish - cleanup after attach |
2478 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 2479 | * |
1958d2d5 TH |
2480 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
2481 | * those functions for details. | |
74a1166d | 2482 | */ |
1958d2d5 | 2483 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
74a1166d | 2484 | { |
1958d2d5 | 2485 | struct css_set *cset, *tmp_cset; |
74a1166d | 2486 | |
1958d2d5 TH |
2487 | lockdep_assert_held(&cgroup_mutex); |
2488 | ||
f0d9a5f1 | 2489 | spin_lock_bh(&css_set_lock); |
1958d2d5 TH |
2490 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { |
2491 | cset->mg_src_cgrp = NULL; | |
2492 | cset->mg_dst_cset = NULL; | |
2493 | list_del_init(&cset->mg_preload_node); | |
a25eb52e | 2494 | put_css_set_locked(cset); |
1958d2d5 | 2495 | } |
f0d9a5f1 | 2496 | spin_unlock_bh(&css_set_lock); |
1958d2d5 TH |
2497 | } |
2498 | ||
2499 | /** | |
2500 | * cgroup_migrate_add_src - add a migration source css_set | |
2501 | * @src_cset: the source css_set to add | |
2502 | * @dst_cgrp: the destination cgroup | |
2503 | * @preloaded_csets: list of preloaded css_sets | |
2504 | * | |
2505 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
2506 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
2507 | * up by cgroup_migrate_finish(). | |
2508 | * | |
1ed13287 TH |
2509 | * This function may be called without holding cgroup_threadgroup_rwsem |
2510 | * even if the target is a process. Threads may be created and destroyed | |
2511 | * but as long as cgroup_mutex is not dropped, no new css_set can be put | |
2512 | * into play and the preloaded css_sets are guaranteed to cover all | |
2513 | * migrations. | |
1958d2d5 TH |
2514 | */ |
2515 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
2516 | struct cgroup *dst_cgrp, | |
2517 | struct list_head *preloaded_csets) | |
2518 | { | |
2519 | struct cgroup *src_cgrp; | |
2520 | ||
2521 | lockdep_assert_held(&cgroup_mutex); | |
f0d9a5f1 | 2522 | lockdep_assert_held(&css_set_lock); |
1958d2d5 TH |
2523 | |
2524 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
2525 | ||
1958d2d5 TH |
2526 | if (!list_empty(&src_cset->mg_preload_node)) |
2527 | return; | |
2528 | ||
2529 | WARN_ON(src_cset->mg_src_cgrp); | |
2530 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
2531 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
2532 | ||
2533 | src_cset->mg_src_cgrp = src_cgrp; | |
2534 | get_css_set(src_cset); | |
2535 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
2536 | } | |
2537 | ||
2538 | /** | |
2539 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
f817de98 | 2540 | * @dst_cgrp: the destination cgroup (may be %NULL) |
1958d2d5 TH |
2541 | * @preloaded_csets: list of preloaded source css_sets |
2542 | * | |
2543 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
2544 | * have been preloaded to @preloaded_csets. This function looks up and | |
f817de98 TH |
2545 | * pins all destination css_sets, links each to its source, and append them |
2546 | * to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each | |
2547 | * source css_set is assumed to be its cgroup on the default hierarchy. | |
1958d2d5 TH |
2548 | * |
2549 | * This function must be called after cgroup_migrate_add_src() has been | |
2550 | * called on each migration source css_set. After migration is performed | |
2551 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
2552 | * @preloaded_csets. | |
2553 | */ | |
2554 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
2555 | struct list_head *preloaded_csets) | |
2556 | { | |
2557 | LIST_HEAD(csets); | |
f817de98 | 2558 | struct css_set *src_cset, *tmp_cset; |
1958d2d5 TH |
2559 | |
2560 | lockdep_assert_held(&cgroup_mutex); | |
2561 | ||
f8f22e53 | 2562 | /* |
62716ea0 | 2563 | * Except for the root, subtree_control must be zero for a cgroup |
f8f22e53 TH |
2564 | * with tasks so that child cgroups don't compete against tasks. |
2565 | */ | |
d51f39b0 | 2566 | if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && |
62716ea0 | 2567 | dst_cgrp->subtree_control) |
f8f22e53 TH |
2568 | return -EBUSY; |
2569 | ||
1958d2d5 | 2570 | /* look up the dst cset for each src cset and link it to src */ |
f817de98 | 2571 | list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) { |
1958d2d5 TH |
2572 | struct css_set *dst_cset; |
2573 | ||
f817de98 TH |
2574 | dst_cset = find_css_set(src_cset, |
2575 | dst_cgrp ?: src_cset->dfl_cgrp); | |
1958d2d5 TH |
2576 | if (!dst_cset) |
2577 | goto err; | |
2578 | ||
2579 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
f817de98 TH |
2580 | |
2581 | /* | |
2582 | * If src cset equals dst, it's noop. Drop the src. | |
2583 | * cgroup_migrate() will skip the cset too. Note that we | |
2584 | * can't handle src == dst as some nodes are used by both. | |
2585 | */ | |
2586 | if (src_cset == dst_cset) { | |
2587 | src_cset->mg_src_cgrp = NULL; | |
2588 | list_del_init(&src_cset->mg_preload_node); | |
a25eb52e ZL |
2589 | put_css_set(src_cset); |
2590 | put_css_set(dst_cset); | |
f817de98 TH |
2591 | continue; |
2592 | } | |
2593 | ||
1958d2d5 TH |
2594 | src_cset->mg_dst_cset = dst_cset; |
2595 | ||
2596 | if (list_empty(&dst_cset->mg_preload_node)) | |
2597 | list_add(&dst_cset->mg_preload_node, &csets); | |
2598 | else | |
a25eb52e | 2599 | put_css_set(dst_cset); |
1958d2d5 TH |
2600 | } |
2601 | ||
f817de98 | 2602 | list_splice_tail(&csets, preloaded_csets); |
1958d2d5 TH |
2603 | return 0; |
2604 | err: | |
2605 | cgroup_migrate_finish(&csets); | |
2606 | return -ENOMEM; | |
2607 | } | |
2608 | ||
2609 | /** | |
2610 | * cgroup_migrate - migrate a process or task to a cgroup | |
1958d2d5 TH |
2611 | * @leader: the leader of the process or the task to migrate |
2612 | * @threadgroup: whether @leader points to the whole process or a single task | |
9af2ec45 | 2613 | * @cgrp: the destination cgroup |
1958d2d5 TH |
2614 | * |
2615 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1ed13287 | 2616 | * process, the caller must be holding cgroup_threadgroup_rwsem. The |
1958d2d5 TH |
2617 | * caller is also responsible for invoking cgroup_migrate_add_src() and |
2618 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
2619 | * function and following up with cgroup_migrate_finish(). | |
2620 | * | |
2621 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
2622 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
2623 | * failure, when migrating multiple targets, the success or failure can be | |
2624 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
2625 | * actually starting migrating. | |
2626 | */ | |
9af2ec45 TH |
2627 | static int cgroup_migrate(struct task_struct *leader, bool threadgroup, |
2628 | struct cgroup *cgrp) | |
74a1166d | 2629 | { |
adaae5dc TH |
2630 | struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
2631 | struct task_struct *task; | |
74a1166d | 2632 | |
fb5d2b4c MSB |
2633 | /* |
2634 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2635 | * already PF_EXITING could be freed from underneath us unless we | |
2636 | * take an rcu_read_lock. | |
2637 | */ | |
f0d9a5f1 | 2638 | spin_lock_bh(&css_set_lock); |
fb5d2b4c | 2639 | rcu_read_lock(); |
9db8de37 | 2640 | task = leader; |
74a1166d | 2641 | do { |
adaae5dc | 2642 | cgroup_taskset_add(task, &tset); |
081aa458 LZ |
2643 | if (!threadgroup) |
2644 | break; | |
9db8de37 | 2645 | } while_each_thread(leader, task); |
fb5d2b4c | 2646 | rcu_read_unlock(); |
f0d9a5f1 | 2647 | spin_unlock_bh(&css_set_lock); |
74a1166d | 2648 | |
adaae5dc | 2649 | return cgroup_taskset_migrate(&tset, cgrp); |
74a1166d BB |
2650 | } |
2651 | ||
1958d2d5 TH |
2652 | /** |
2653 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
2654 | * @dst_cgrp: the cgroup to attach to | |
2655 | * @leader: the task or the leader of the threadgroup to be attached | |
2656 | * @threadgroup: attach the whole threadgroup? | |
2657 | * | |
1ed13287 | 2658 | * Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
1958d2d5 TH |
2659 | */ |
2660 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2661 | struct task_struct *leader, bool threadgroup) | |
2662 | { | |
2663 | LIST_HEAD(preloaded_csets); | |
2664 | struct task_struct *task; | |
2665 | int ret; | |
2666 | ||
2667 | /* look up all src csets */ | |
f0d9a5f1 | 2668 | spin_lock_bh(&css_set_lock); |
1958d2d5 TH |
2669 | rcu_read_lock(); |
2670 | task = leader; | |
2671 | do { | |
2672 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2673 | &preloaded_csets); | |
2674 | if (!threadgroup) | |
2675 | break; | |
2676 | } while_each_thread(leader, task); | |
2677 | rcu_read_unlock(); | |
f0d9a5f1 | 2678 | spin_unlock_bh(&css_set_lock); |
1958d2d5 TH |
2679 | |
2680 | /* prepare dst csets and commit */ | |
2681 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2682 | if (!ret) | |
9af2ec45 | 2683 | ret = cgroup_migrate(leader, threadgroup, dst_cgrp); |
1958d2d5 TH |
2684 | |
2685 | cgroup_migrate_finish(&preloaded_csets); | |
2686 | return ret; | |
74a1166d BB |
2687 | } |
2688 | ||
187fe840 TH |
2689 | static int cgroup_procs_write_permission(struct task_struct *task, |
2690 | struct cgroup *dst_cgrp, | |
2691 | struct kernfs_open_file *of) | |
dedf22e9 TH |
2692 | { |
2693 | const struct cred *cred = current_cred(); | |
2694 | const struct cred *tcred = get_task_cred(task); | |
2695 | int ret = 0; | |
2696 | ||
2697 | /* | |
2698 | * even if we're attaching all tasks in the thread group, we only | |
2699 | * need to check permissions on one of them. | |
2700 | */ | |
2701 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && | |
2702 | !uid_eq(cred->euid, tcred->uid) && | |
2703 | !uid_eq(cred->euid, tcred->suid)) | |
2704 | ret = -EACCES; | |
2705 | ||
187fe840 TH |
2706 | if (!ret && cgroup_on_dfl(dst_cgrp)) { |
2707 | struct super_block *sb = of->file->f_path.dentry->d_sb; | |
2708 | struct cgroup *cgrp; | |
2709 | struct inode *inode; | |
2710 | ||
f0d9a5f1 | 2711 | spin_lock_bh(&css_set_lock); |
187fe840 | 2712 | cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); |
f0d9a5f1 | 2713 | spin_unlock_bh(&css_set_lock); |
187fe840 TH |
2714 | |
2715 | while (!cgroup_is_descendant(dst_cgrp, cgrp)) | |
2716 | cgrp = cgroup_parent(cgrp); | |
2717 | ||
2718 | ret = -ENOMEM; | |
6f60eade | 2719 | inode = kernfs_get_inode(sb, cgrp->procs_file.kn); |
187fe840 TH |
2720 | if (inode) { |
2721 | ret = inode_permission(inode, MAY_WRITE); | |
2722 | iput(inode); | |
2723 | } | |
2724 | } | |
2725 | ||
dedf22e9 TH |
2726 | put_cred(tcred); |
2727 | return ret; | |
2728 | } | |
2729 | ||
74a1166d BB |
2730 | /* |
2731 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 | 2732 | * function to attach either it or all tasks in its threadgroup. Will lock |
0e1d768f | 2733 | * cgroup_mutex and threadgroup. |
bbcb81d0 | 2734 | */ |
acbef755 TH |
2735 | static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
2736 | size_t nbytes, loff_t off, bool threadgroup) | |
bbcb81d0 | 2737 | { |
bbcb81d0 | 2738 | struct task_struct *tsk; |
e76ecaee | 2739 | struct cgroup *cgrp; |
acbef755 | 2740 | pid_t pid; |
bbcb81d0 PM |
2741 | int ret; |
2742 | ||
acbef755 TH |
2743 | if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
2744 | return -EINVAL; | |
2745 | ||
e76ecaee TH |
2746 | cgrp = cgroup_kn_lock_live(of->kn); |
2747 | if (!cgrp) | |
74a1166d BB |
2748 | return -ENODEV; |
2749 | ||
3014dde7 | 2750 | percpu_down_write(&cgroup_threadgroup_rwsem); |
b78949eb | 2751 | rcu_read_lock(); |
bbcb81d0 | 2752 | if (pid) { |
73507f33 | 2753 | tsk = find_task_by_vpid(pid); |
74a1166d | 2754 | if (!tsk) { |
dd4b0a46 | 2755 | ret = -ESRCH; |
3014dde7 | 2756 | goto out_unlock_rcu; |
bbcb81d0 | 2757 | } |
dedf22e9 | 2758 | } else { |
b78949eb | 2759 | tsk = current; |
dedf22e9 | 2760 | } |
cd3d0952 TH |
2761 | |
2762 | if (threadgroup) | |
b78949eb | 2763 | tsk = tsk->group_leader; |
c4c27fbd MG |
2764 | |
2765 | /* | |
14a40ffc | 2766 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2767 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2768 | * with no rt_runtime allocated. Just say no. | |
2769 | */ | |
14a40ffc | 2770 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd | 2771 | ret = -EINVAL; |
3014dde7 | 2772 | goto out_unlock_rcu; |
c4c27fbd MG |
2773 | } |
2774 | ||
b78949eb MSB |
2775 | get_task_struct(tsk); |
2776 | rcu_read_unlock(); | |
2777 | ||
187fe840 | 2778 | ret = cgroup_procs_write_permission(tsk, cgrp, of); |
dedf22e9 TH |
2779 | if (!ret) |
2780 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
081aa458 | 2781 | |
f9f9e7b7 | 2782 | put_task_struct(tsk); |
3014dde7 TH |
2783 | goto out_unlock_threadgroup; |
2784 | ||
2785 | out_unlock_rcu: | |
2786 | rcu_read_unlock(); | |
2787 | out_unlock_threadgroup: | |
2788 | percpu_up_write(&cgroup_threadgroup_rwsem); | |
e76ecaee | 2789 | cgroup_kn_unlock(of->kn); |
e93ad19d | 2790 | cpuset_post_attach_flush(); |
acbef755 | 2791 | return ret ?: nbytes; |
bbcb81d0 PM |
2792 | } |
2793 | ||
7ae1bad9 TH |
2794 | /** |
2795 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2796 | * @from: attach to all cgroups of a given task | |
2797 | * @tsk: the task to be attached | |
2798 | */ | |
2799 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2800 | { | |
3dd06ffa | 2801 | struct cgroup_root *root; |
7ae1bad9 TH |
2802 | int retval = 0; |
2803 | ||
47cfcd09 | 2804 | mutex_lock(&cgroup_mutex); |
985ed670 | 2805 | for_each_root(root) { |
96d365e0 TH |
2806 | struct cgroup *from_cgrp; |
2807 | ||
3dd06ffa | 2808 | if (root == &cgrp_dfl_root) |
985ed670 TH |
2809 | continue; |
2810 | ||
f0d9a5f1 | 2811 | spin_lock_bh(&css_set_lock); |
96d365e0 | 2812 | from_cgrp = task_cgroup_from_root(from, root); |
f0d9a5f1 | 2813 | spin_unlock_bh(&css_set_lock); |
7ae1bad9 | 2814 | |
6f4b7e63 | 2815 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2816 | if (retval) |
2817 | break; | |
2818 | } | |
47cfcd09 | 2819 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2820 | |
2821 | return retval; | |
2822 | } | |
2823 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2824 | ||
acbef755 TH |
2825 | static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, |
2826 | char *buf, size_t nbytes, loff_t off) | |
74a1166d | 2827 | { |
acbef755 | 2828 | return __cgroup_procs_write(of, buf, nbytes, off, false); |
74a1166d BB |
2829 | } |
2830 | ||
acbef755 TH |
2831 | static ssize_t cgroup_procs_write(struct kernfs_open_file *of, |
2832 | char *buf, size_t nbytes, loff_t off) | |
af351026 | 2833 | { |
acbef755 | 2834 | return __cgroup_procs_write(of, buf, nbytes, off, true); |
af351026 PM |
2835 | } |
2836 | ||
451af504 TH |
2837 | static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
2838 | char *buf, size_t nbytes, loff_t off) | |
e788e066 | 2839 | { |
e76ecaee | 2840 | struct cgroup *cgrp; |
5f469907 | 2841 | |
e76ecaee | 2842 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
5f469907 | 2843 | |
e76ecaee TH |
2844 | cgrp = cgroup_kn_lock_live(of->kn); |
2845 | if (!cgrp) | |
e788e066 | 2846 | return -ENODEV; |
69e943b7 | 2847 | spin_lock(&release_agent_path_lock); |
e76ecaee TH |
2848 | strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
2849 | sizeof(cgrp->root->release_agent_path)); | |
69e943b7 | 2850 | spin_unlock(&release_agent_path_lock); |
e76ecaee | 2851 | cgroup_kn_unlock(of->kn); |
451af504 | 2852 | return nbytes; |
e788e066 PM |
2853 | } |
2854 | ||
2da8ca82 | 2855 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2856 | { |
2da8ca82 | 2857 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2858 | |
46cfeb04 | 2859 | spin_lock(&release_agent_path_lock); |
e788e066 | 2860 | seq_puts(seq, cgrp->root->release_agent_path); |
46cfeb04 | 2861 | spin_unlock(&release_agent_path_lock); |
e788e066 | 2862 | seq_putc(seq, '\n'); |
e788e066 PM |
2863 | return 0; |
2864 | } | |
2865 | ||
2da8ca82 | 2866 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2867 | { |
c1d5d42e | 2868 | seq_puts(seq, "0\n"); |
e788e066 PM |
2869 | return 0; |
2870 | } | |
2871 | ||
6e5c8307 | 2872 | static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask) |
355e0c48 | 2873 | { |
f8f22e53 TH |
2874 | struct cgroup_subsys *ss; |
2875 | bool printed = false; | |
2876 | int ssid; | |
a742c59d | 2877 | |
b4e0eeaf | 2878 | do_each_subsys_mask(ss, ssid, ss_mask) { |
a966a4ed AS |
2879 | if (printed) |
2880 | seq_putc(seq, ' '); | |
2881 | seq_printf(seq, "%s", ss->name); | |
2882 | printed = true; | |
b4e0eeaf | 2883 | } while_each_subsys_mask(); |
f8f22e53 TH |
2884 | if (printed) |
2885 | seq_putc(seq, '\n'); | |
355e0c48 PM |
2886 | } |
2887 | ||
f8f22e53 TH |
2888 | /* show controllers which are enabled from the parent */ |
2889 | static int cgroup_controllers_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2890 | { |
f8f22e53 TH |
2891 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2892 | ||
5531dc91 | 2893 | cgroup_print_ss_mask(seq, cgroup_control(cgrp)); |
f8f22e53 | 2894 | return 0; |
ddbcc7e8 PM |
2895 | } |
2896 | ||
f8f22e53 TH |
2897 | /* show controllers which are enabled for a given cgroup's children */ |
2898 | static int cgroup_subtree_control_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2899 | { |
f8f22e53 TH |
2900 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2901 | ||
667c2491 | 2902 | cgroup_print_ss_mask(seq, cgrp->subtree_control); |
f8f22e53 TH |
2903 | return 0; |
2904 | } | |
2905 | ||
2906 | /** | |
2907 | * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy | |
2908 | * @cgrp: root of the subtree to update csses for | |
2909 | * | |
8699b776 | 2910 | * @cgrp's subtree_ss_mask has changed and its subtree's (self excluded) |
f8f22e53 TH |
2911 | * css associations need to be updated accordingly. This function looks up |
2912 | * all css_sets which are attached to the subtree, creates the matching | |
2913 | * updated css_sets and migrates the tasks to the new ones. | |
2914 | */ | |
2915 | static int cgroup_update_dfl_csses(struct cgroup *cgrp) | |
2916 | { | |
2917 | LIST_HEAD(preloaded_csets); | |
10265075 | 2918 | struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
f8f22e53 TH |
2919 | struct cgroup_subsys_state *css; |
2920 | struct css_set *src_cset; | |
2921 | int ret; | |
2922 | ||
f8f22e53 TH |
2923 | lockdep_assert_held(&cgroup_mutex); |
2924 | ||
3014dde7 TH |
2925 | percpu_down_write(&cgroup_threadgroup_rwsem); |
2926 | ||
f8f22e53 | 2927 | /* look up all csses currently attached to @cgrp's subtree */ |
f0d9a5f1 | 2928 | spin_lock_bh(&css_set_lock); |
f8f22e53 TH |
2929 | css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) { |
2930 | struct cgrp_cset_link *link; | |
2931 | ||
8699b776 | 2932 | /* self is not affected by subtree_ss_mask change */ |
f8f22e53 TH |
2933 | if (css->cgroup == cgrp) |
2934 | continue; | |
2935 | ||
2936 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) | |
2937 | cgroup_migrate_add_src(link->cset, cgrp, | |
2938 | &preloaded_csets); | |
2939 | } | |
f0d9a5f1 | 2940 | spin_unlock_bh(&css_set_lock); |
f8f22e53 TH |
2941 | |
2942 | /* NULL dst indicates self on default hierarchy */ | |
2943 | ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets); | |
2944 | if (ret) | |
2945 | goto out_finish; | |
2946 | ||
f0d9a5f1 | 2947 | spin_lock_bh(&css_set_lock); |
f8f22e53 | 2948 | list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { |
10265075 | 2949 | struct task_struct *task, *ntask; |
f8f22e53 TH |
2950 | |
2951 | /* src_csets precede dst_csets, break on the first dst_cset */ | |
2952 | if (!src_cset->mg_src_cgrp) | |
2953 | break; | |
2954 | ||
10265075 TH |
2955 | /* all tasks in src_csets need to be migrated */ |
2956 | list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) | |
2957 | cgroup_taskset_add(task, &tset); | |
f8f22e53 | 2958 | } |
f0d9a5f1 | 2959 | spin_unlock_bh(&css_set_lock); |
f8f22e53 | 2960 | |
10265075 | 2961 | ret = cgroup_taskset_migrate(&tset, cgrp); |
f8f22e53 TH |
2962 | out_finish: |
2963 | cgroup_migrate_finish(&preloaded_csets); | |
3014dde7 | 2964 | percpu_up_write(&cgroup_threadgroup_rwsem); |
f8f22e53 TH |
2965 | return ret; |
2966 | } | |
2967 | ||
2968 | /* change the enabled child controllers for a cgroup in the default hierarchy */ | |
451af504 TH |
2969 | static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
2970 | char *buf, size_t nbytes, | |
2971 | loff_t off) | |
f8f22e53 | 2972 | { |
6e5c8307 TH |
2973 | u16 enable = 0, disable = 0; |
2974 | u16 css_enable, css_disable, old_sc, new_sc, old_ss, new_ss; | |
a9746d8d | 2975 | struct cgroup *cgrp, *child; |
f8f22e53 | 2976 | struct cgroup_subsys *ss; |
451af504 | 2977 | char *tok; |
f8f22e53 TH |
2978 | int ssid, ret; |
2979 | ||
2980 | /* | |
d37167ab TH |
2981 | * Parse input - space separated list of subsystem names prefixed |
2982 | * with either + or -. | |
f8f22e53 | 2983 | */ |
451af504 TH |
2984 | buf = strstrip(buf); |
2985 | while ((tok = strsep(&buf, " "))) { | |
d37167ab TH |
2986 | if (tok[0] == '\0') |
2987 | continue; | |
a7165264 | 2988 | do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) { |
fc5ed1e9 TH |
2989 | if (!cgroup_ssid_enabled(ssid) || |
2990 | strcmp(tok + 1, ss->name)) | |
f8f22e53 TH |
2991 | continue; |
2992 | ||
2993 | if (*tok == '+') { | |
7d331fa9 TH |
2994 | enable |= 1 << ssid; |
2995 | disable &= ~(1 << ssid); | |
f8f22e53 | 2996 | } else if (*tok == '-') { |
7d331fa9 TH |
2997 | disable |= 1 << ssid; |
2998 | enable &= ~(1 << ssid); | |
f8f22e53 TH |
2999 | } else { |
3000 | return -EINVAL; | |
3001 | } | |
3002 | break; | |
b4e0eeaf | 3003 | } while_each_subsys_mask(); |
f8f22e53 TH |
3004 | if (ssid == CGROUP_SUBSYS_COUNT) |
3005 | return -EINVAL; | |
3006 | } | |
3007 | ||
a9746d8d TH |
3008 | cgrp = cgroup_kn_lock_live(of->kn); |
3009 | if (!cgrp) | |
3010 | return -ENODEV; | |
f8f22e53 TH |
3011 | |
3012 | for_each_subsys(ss, ssid) { | |
3013 | if (enable & (1 << ssid)) { | |
667c2491 | 3014 | if (cgrp->subtree_control & (1 << ssid)) { |
f8f22e53 TH |
3015 | enable &= ~(1 << ssid); |
3016 | continue; | |
3017 | } | |
3018 | ||
5531dc91 | 3019 | if (!(cgroup_control(cgrp) & (1 << ssid))) { |
c29adf24 TH |
3020 | ret = -ENOENT; |
3021 | goto out_unlock; | |
3022 | } | |
f8f22e53 | 3023 | } else if (disable & (1 << ssid)) { |
667c2491 | 3024 | if (!(cgrp->subtree_control & (1 << ssid))) { |
f8f22e53 TH |
3025 | disable &= ~(1 << ssid); |
3026 | continue; | |
3027 | } | |
3028 | ||
3029 | /* a child has it enabled? */ | |
3030 | cgroup_for_each_live_child(child, cgrp) { | |
667c2491 | 3031 | if (child->subtree_control & (1 << ssid)) { |
f8f22e53 | 3032 | ret = -EBUSY; |
ddab2b6e | 3033 | goto out_unlock; |
f8f22e53 TH |
3034 | } |
3035 | } | |
3036 | } | |
3037 | } | |
3038 | ||
3039 | if (!enable && !disable) { | |
3040 | ret = 0; | |
ddab2b6e | 3041 | goto out_unlock; |
f8f22e53 TH |
3042 | } |
3043 | ||
3044 | /* | |
667c2491 | 3045 | * Except for the root, subtree_control must be zero for a cgroup |
f8f22e53 TH |
3046 | * with tasks so that child cgroups don't compete against tasks. |
3047 | */ | |
d51f39b0 | 3048 | if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) { |
f8f22e53 TH |
3049 | ret = -EBUSY; |
3050 | goto out_unlock; | |
3051 | } | |
3052 | ||
3053 | /* | |
f63070d3 TH |
3054 | * Update subsys masks and calculate what needs to be done. More |
3055 | * subsystems than specified may need to be enabled or disabled | |
3056 | * depending on subsystem dependencies. | |
3057 | */ | |
755bf5ee | 3058 | old_sc = cgrp->subtree_control; |
8699b776 | 3059 | old_ss = cgrp->subtree_ss_mask; |
755bf5ee | 3060 | new_sc = (old_sc | enable) & ~disable; |
8699b776 | 3061 | new_ss = cgroup_calc_subtree_ss_mask(cgrp, new_sc); |
f63070d3 | 3062 | |
755bf5ee TH |
3063 | css_enable = ~old_ss & new_ss; |
3064 | css_disable = old_ss & ~new_ss; | |
f63070d3 TH |
3065 | enable |= css_enable; |
3066 | disable |= css_disable; | |
c29adf24 | 3067 | |
db6e3053 TH |
3068 | /* |
3069 | * Because css offlining is asynchronous, userland might try to | |
3070 | * re-enable the same controller while the previous instance is | |
3071 | * still around. In such cases, wait till it's gone using | |
3072 | * offline_waitq. | |
3073 | */ | |
b4e0eeaf | 3074 | do_each_subsys_mask(ss, ssid, css_enable) { |
db6e3053 TH |
3075 | cgroup_for_each_live_child(child, cgrp) { |
3076 | DEFINE_WAIT(wait); | |
3077 | ||
3078 | if (!cgroup_css(child, ss)) | |
3079 | continue; | |
3080 | ||
3081 | cgroup_get(child); | |
3082 | prepare_to_wait(&child->offline_waitq, &wait, | |
3083 | TASK_UNINTERRUPTIBLE); | |
3084 | cgroup_kn_unlock(of->kn); | |
3085 | schedule(); | |
3086 | finish_wait(&child->offline_waitq, &wait); | |
3087 | cgroup_put(child); | |
3088 | ||
3089 | return restart_syscall(); | |
3090 | } | |
b4e0eeaf | 3091 | } while_each_subsys_mask(); |
db6e3053 | 3092 | |
755bf5ee | 3093 | cgrp->subtree_control = new_sc; |
8699b776 | 3094 | cgrp->subtree_ss_mask = new_ss; |
755bf5ee | 3095 | |
f63070d3 TH |
3096 | /* |
3097 | * Create new csses or make the existing ones visible. A css is | |
3098 | * created invisible if it's being implicitly enabled through | |
3099 | * dependency. An invisible css is made visible when the userland | |
3100 | * explicitly enables it. | |
f8f22e53 | 3101 | */ |
996cd1fb | 3102 | do_each_subsys_mask(ss, ssid, enable) { |
f8f22e53 | 3103 | cgroup_for_each_live_child(child, cgrp) { |
6cd0f5bb TH |
3104 | if (css_enable & (1 << ssid)) { |
3105 | struct cgroup_subsys_state *css; | |
3106 | ||
3107 | css = css_create(child, ss); | |
3108 | if (IS_ERR(css)) { | |
3109 | ret = PTR_ERR(css); | |
3110 | goto err_undo_css; | |
3111 | } | |
3112 | ||
3113 | if (cgrp->subtree_control & (1 << ssid)) { | |
3114 | ret = css_populate_dir(css, NULL); | |
3115 | if (ret) | |
3116 | goto err_undo_css; | |
3117 | } | |
3118 | } else { | |
4df8dc90 TH |
3119 | ret = css_populate_dir(cgroup_css(child, ss), |
3120 | NULL); | |
6cd0f5bb TH |
3121 | if (ret) |
3122 | goto err_undo_css; | |
3123 | } | |
f8f22e53 | 3124 | } |
996cd1fb | 3125 | } while_each_subsys_mask(); |
f8f22e53 | 3126 | |
c29adf24 TH |
3127 | /* |
3128 | * At this point, cgroup_e_css() results reflect the new csses | |
3129 | * making the following cgroup_update_dfl_csses() properly update | |
3130 | * css associations of all tasks in the subtree. | |
3131 | */ | |
f8f22e53 TH |
3132 | ret = cgroup_update_dfl_csses(cgrp); |
3133 | if (ret) | |
3134 | goto err_undo_css; | |
3135 | ||
f63070d3 TH |
3136 | /* |
3137 | * All tasks are migrated out of disabled csses. Kill or hide | |
3138 | * them. A css is hidden when the userland requests it to be | |
b4536f0c TH |
3139 | * disabled while other subsystems are still depending on it. The |
3140 | * css must not actively control resources and be in the vanilla | |
3141 | * state if it's made visible again later. Controllers which may | |
3142 | * be depended upon should provide ->css_reset() for this purpose. | |
f63070d3 | 3143 | */ |
996cd1fb | 3144 | do_each_subsys_mask(ss, ssid, disable) { |
f63070d3 | 3145 | cgroup_for_each_live_child(child, cgrp) { |
b4536f0c TH |
3146 | struct cgroup_subsys_state *css = cgroup_css(child, ss); |
3147 | ||
3148 | if (css_disable & (1 << ssid)) { | |
3149 | kill_css(css); | |
3150 | } else { | |
4df8dc90 | 3151 | css_clear_dir(css, NULL); |
b4536f0c TH |
3152 | if (ss->css_reset) |
3153 | ss->css_reset(css); | |
3154 | } | |
f63070d3 | 3155 | } |
996cd1fb | 3156 | } while_each_subsys_mask(); |
f8f22e53 TH |
3157 | |
3158 | kernfs_activate(cgrp->kn); | |
3159 | ret = 0; | |
3160 | out_unlock: | |
a9746d8d | 3161 | cgroup_kn_unlock(of->kn); |
451af504 | 3162 | return ret ?: nbytes; |
f8f22e53 TH |
3163 | |
3164 | err_undo_css: | |
755bf5ee | 3165 | cgrp->subtree_control = old_sc; |
8699b776 | 3166 | cgrp->subtree_ss_mask = old_ss; |
f8f22e53 | 3167 | |
996cd1fb | 3168 | do_each_subsys_mask(ss, ssid, enable) { |
f8f22e53 TH |
3169 | cgroup_for_each_live_child(child, cgrp) { |
3170 | struct cgroup_subsys_state *css = cgroup_css(child, ss); | |
f63070d3 TH |
3171 | |
3172 | if (!css) | |
3173 | continue; | |
3174 | ||
3175 | if (css_enable & (1 << ssid)) | |
f8f22e53 | 3176 | kill_css(css); |
f63070d3 | 3177 | else |
4df8dc90 | 3178 | css_clear_dir(css, NULL); |
f8f22e53 | 3179 | } |
996cd1fb | 3180 | } while_each_subsys_mask(); |
f8f22e53 TH |
3181 | goto out_unlock; |
3182 | } | |
3183 | ||
4a07c222 | 3184 | static int cgroup_events_show(struct seq_file *seq, void *v) |
842b597e | 3185 | { |
4a07c222 | 3186 | seq_printf(seq, "populated %d\n", |
27bd4dbb | 3187 | cgroup_is_populated(seq_css(seq)->cgroup)); |
842b597e TH |
3188 | return 0; |
3189 | } | |
3190 | ||
2bd59d48 TH |
3191 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
3192 | size_t nbytes, loff_t off) | |
355e0c48 | 3193 | { |
2bd59d48 TH |
3194 | struct cgroup *cgrp = of->kn->parent->priv; |
3195 | struct cftype *cft = of->kn->priv; | |
3196 | struct cgroup_subsys_state *css; | |
a742c59d | 3197 | int ret; |
355e0c48 | 3198 | |
b4168640 TH |
3199 | if (cft->write) |
3200 | return cft->write(of, buf, nbytes, off); | |
3201 | ||
2bd59d48 TH |
3202 | /* |
3203 | * kernfs guarantees that a file isn't deleted with operations in | |
3204 | * flight, which means that the matching css is and stays alive and | |
3205 | * doesn't need to be pinned. The RCU locking is not necessary | |
3206 | * either. It's just for the convenience of using cgroup_css(). | |
3207 | */ | |
3208 | rcu_read_lock(); | |
3209 | css = cgroup_css(cgrp, cft->ss); | |
3210 | rcu_read_unlock(); | |
a742c59d | 3211 | |
451af504 | 3212 | if (cft->write_u64) { |
a742c59d TH |
3213 | unsigned long long v; |
3214 | ret = kstrtoull(buf, 0, &v); | |
3215 | if (!ret) | |
3216 | ret = cft->write_u64(css, cft, v); | |
3217 | } else if (cft->write_s64) { | |
3218 | long long v; | |
3219 | ret = kstrtoll(buf, 0, &v); | |
3220 | if (!ret) | |
3221 | ret = cft->write_s64(css, cft, v); | |
e73d2c61 | 3222 | } else { |
a742c59d | 3223 | ret = -EINVAL; |
e73d2c61 | 3224 | } |
2bd59d48 | 3225 | |
a742c59d | 3226 | return ret ?: nbytes; |
355e0c48 PM |
3227 | } |
3228 | ||
6612f05b | 3229 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 3230 | { |
2bd59d48 | 3231 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
3232 | } |
3233 | ||
6612f05b | 3234 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 3235 | { |
2bd59d48 | 3236 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
3237 | } |
3238 | ||
6612f05b | 3239 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 3240 | { |
2bd59d48 | 3241 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
3242 | } |
3243 | ||
91796569 | 3244 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 3245 | { |
7da11279 TH |
3246 | struct cftype *cft = seq_cft(m); |
3247 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 3248 | |
2da8ca82 TH |
3249 | if (cft->seq_show) |
3250 | return cft->seq_show(m, arg); | |
e73d2c61 | 3251 | |
f4c753b7 | 3252 | if (cft->read_u64) |
896f5199 TH |
3253 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
3254 | else if (cft->read_s64) | |
3255 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
3256 | else | |
3257 | return -EINVAL; | |
3258 | return 0; | |
91796569 PM |
3259 | } |
3260 | ||
2bd59d48 TH |
3261 | static struct kernfs_ops cgroup_kf_single_ops = { |
3262 | .atomic_write_len = PAGE_SIZE, | |
3263 | .write = cgroup_file_write, | |
3264 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
3265 | }; |
3266 | ||
2bd59d48 TH |
3267 | static struct kernfs_ops cgroup_kf_ops = { |
3268 | .atomic_write_len = PAGE_SIZE, | |
3269 | .write = cgroup_file_write, | |
3270 | .seq_start = cgroup_seqfile_start, | |
3271 | .seq_next = cgroup_seqfile_next, | |
3272 | .seq_stop = cgroup_seqfile_stop, | |
3273 | .seq_show = cgroup_seqfile_show, | |
3274 | }; | |
ddbcc7e8 PM |
3275 | |
3276 | /* | |
3277 | * cgroup_rename - Only allow simple rename of directories in place. | |
3278 | */ | |
2bd59d48 TH |
3279 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
3280 | const char *new_name_str) | |
ddbcc7e8 | 3281 | { |
2bd59d48 | 3282 | struct cgroup *cgrp = kn->priv; |
65dff759 | 3283 | int ret; |
65dff759 | 3284 | |
2bd59d48 | 3285 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 3286 | return -ENOTDIR; |
2bd59d48 | 3287 | if (kn->parent != new_parent) |
ddbcc7e8 | 3288 | return -EIO; |
65dff759 | 3289 | |
6db8e85c TH |
3290 | /* |
3291 | * This isn't a proper migration and its usefulness is very | |
aa6ec29b | 3292 | * limited. Disallow on the default hierarchy. |
6db8e85c | 3293 | */ |
aa6ec29b | 3294 | if (cgroup_on_dfl(cgrp)) |
6db8e85c | 3295 | return -EPERM; |
099fca32 | 3296 | |
e1b2dc17 | 3297 | /* |
8353da1f | 3298 | * We're gonna grab cgroup_mutex which nests outside kernfs |
e1b2dc17 | 3299 | * active_ref. kernfs_rename() doesn't require active_ref |
8353da1f | 3300 | * protection. Break them before grabbing cgroup_mutex. |
e1b2dc17 TH |
3301 | */ |
3302 | kernfs_break_active_protection(new_parent); | |
3303 | kernfs_break_active_protection(kn); | |
099fca32 | 3304 | |
2bd59d48 | 3305 | mutex_lock(&cgroup_mutex); |
099fca32 | 3306 | |
2bd59d48 | 3307 | ret = kernfs_rename(kn, new_parent, new_name_str); |
099fca32 | 3308 | |
2bd59d48 | 3309 | mutex_unlock(&cgroup_mutex); |
e1b2dc17 TH |
3310 | |
3311 | kernfs_unbreak_active_protection(kn); | |
3312 | kernfs_unbreak_active_protection(new_parent); | |
2bd59d48 | 3313 | return ret; |
099fca32 LZ |
3314 | } |
3315 | ||
49957f8e TH |
3316 | /* set uid and gid of cgroup dirs and files to that of the creator */ |
3317 | static int cgroup_kn_set_ugid(struct kernfs_node *kn) | |
3318 | { | |
3319 | struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, | |
3320 | .ia_uid = current_fsuid(), | |
3321 | .ia_gid = current_fsgid(), }; | |
3322 | ||
3323 | if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && | |
3324 | gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) | |
3325 | return 0; | |
3326 | ||
3327 | return kernfs_setattr(kn, &iattr); | |
3328 | } | |
3329 | ||
4df8dc90 TH |
3330 | static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, |
3331 | struct cftype *cft) | |
ddbcc7e8 | 3332 | { |
8d7e6fb0 | 3333 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
3334 | struct kernfs_node *kn; |
3335 | struct lock_class_key *key = NULL; | |
49957f8e | 3336 | int ret; |
05ef1d7c | 3337 | |
2bd59d48 TH |
3338 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
3339 | key = &cft->lockdep_key; | |
3340 | #endif | |
3341 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
3342 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
dfeb0750 | 3343 | NULL, key); |
49957f8e TH |
3344 | if (IS_ERR(kn)) |
3345 | return PTR_ERR(kn); | |
3346 | ||
3347 | ret = cgroup_kn_set_ugid(kn); | |
f8f22e53 | 3348 | if (ret) { |
49957f8e | 3349 | kernfs_remove(kn); |
f8f22e53 TH |
3350 | return ret; |
3351 | } | |
3352 | ||
6f60eade TH |
3353 | if (cft->file_offset) { |
3354 | struct cgroup_file *cfile = (void *)css + cft->file_offset; | |
3355 | ||
34c06254 | 3356 | spin_lock_irq(&cgroup_file_kn_lock); |
6f60eade | 3357 | cfile->kn = kn; |
34c06254 | 3358 | spin_unlock_irq(&cgroup_file_kn_lock); |
6f60eade TH |
3359 | } |
3360 | ||
f8f22e53 | 3361 | return 0; |
ddbcc7e8 PM |
3362 | } |
3363 | ||
b1f28d31 TH |
3364 | /** |
3365 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
4df8dc90 TH |
3366 | * @css: the target css |
3367 | * @cgrp: the target cgroup (usually css->cgroup) | |
b1f28d31 TH |
3368 | * @cfts: array of cftypes to be added |
3369 | * @is_add: whether to add or remove | |
3370 | * | |
3371 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
6732ed85 | 3372 | * For removals, this function never fails. |
b1f28d31 | 3373 | */ |
4df8dc90 TH |
3374 | static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
3375 | struct cgroup *cgrp, struct cftype cfts[], | |
2bb566cb | 3376 | bool is_add) |
ddbcc7e8 | 3377 | { |
6732ed85 | 3378 | struct cftype *cft, *cft_end = NULL; |
b598dde3 | 3379 | int ret = 0; |
b1f28d31 | 3380 | |
01f6474c | 3381 | lockdep_assert_held(&cgroup_mutex); |
db0416b6 | 3382 | |
6732ed85 TH |
3383 | restart: |
3384 | for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 3385 | /* does cft->flags tell us to skip this file on @cgrp? */ |
05ebb6e6 | 3386 | if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
8cbbf2c9 | 3387 | continue; |
05ebb6e6 | 3388 | if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) |
873fe09e | 3389 | continue; |
d51f39b0 | 3390 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp)) |
f33fddc2 | 3391 | continue; |
d51f39b0 | 3392 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp)) |
f33fddc2 G |
3393 | continue; |
3394 | ||
2739d3cc | 3395 | if (is_add) { |
4df8dc90 | 3396 | ret = cgroup_add_file(css, cgrp, cft); |
b1f28d31 | 3397 | if (ret) { |
ed3d261b JP |
3398 | pr_warn("%s: failed to add %s, err=%d\n", |
3399 | __func__, cft->name, ret); | |
6732ed85 TH |
3400 | cft_end = cft; |
3401 | is_add = false; | |
3402 | goto restart; | |
b1f28d31 | 3403 | } |
2739d3cc LZ |
3404 | } else { |
3405 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 3406 | } |
ddbcc7e8 | 3407 | } |
b598dde3 | 3408 | return ret; |
ddbcc7e8 PM |
3409 | } |
3410 | ||
21a2d343 | 3411 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
3412 | { |
3413 | LIST_HEAD(pending); | |
2bb566cb | 3414 | struct cgroup_subsys *ss = cfts[0].ss; |
3dd06ffa | 3415 | struct cgroup *root = &ss->root->cgrp; |
492eb21b | 3416 | struct cgroup_subsys_state *css; |
9ccece80 | 3417 | int ret = 0; |
8e3f6541 | 3418 | |
01f6474c | 3419 | lockdep_assert_held(&cgroup_mutex); |
e8c82d20 | 3420 | |
e8c82d20 | 3421 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 3422 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
3423 | struct cgroup *cgrp = css->cgroup; |
3424 | ||
88cb04b9 | 3425 | if (!(css->flags & CSS_VISIBLE)) |
e8c82d20 LZ |
3426 | continue; |
3427 | ||
4df8dc90 | 3428 | ret = cgroup_addrm_files(css, cgrp, cfts, is_add); |
9ccece80 TH |
3429 | if (ret) |
3430 | break; | |
8e3f6541 | 3431 | } |
21a2d343 TH |
3432 | |
3433 | if (is_add && !ret) | |
3434 | kernfs_activate(root->kn); | |
9ccece80 | 3435 | return ret; |
8e3f6541 TH |
3436 | } |
3437 | ||
2da440a2 | 3438 | static void cgroup_exit_cftypes(struct cftype *cfts) |
8e3f6541 | 3439 | { |
2bb566cb | 3440 | struct cftype *cft; |
8e3f6541 | 3441 | |
2bd59d48 TH |
3442 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3443 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
3444 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
3445 | kfree(cft->kf_ops); | |
3446 | cft->kf_ops = NULL; | |
2da440a2 | 3447 | cft->ss = NULL; |
a8ddc821 TH |
3448 | |
3449 | /* revert flags set by cgroup core while adding @cfts */ | |
05ebb6e6 | 3450 | cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
2bd59d48 | 3451 | } |
2da440a2 TH |
3452 | } |
3453 | ||
2bd59d48 | 3454 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
3455 | { |
3456 | struct cftype *cft; | |
3457 | ||
2bd59d48 TH |
3458 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3459 | struct kernfs_ops *kf_ops; | |
3460 | ||
0adb0704 TH |
3461 | WARN_ON(cft->ss || cft->kf_ops); |
3462 | ||
2bd59d48 TH |
3463 | if (cft->seq_start) |
3464 | kf_ops = &cgroup_kf_ops; | |
3465 | else | |
3466 | kf_ops = &cgroup_kf_single_ops; | |
3467 | ||
3468 | /* | |
3469 | * Ugh... if @cft wants a custom max_write_len, we need to | |
3470 | * make a copy of kf_ops to set its atomic_write_len. | |
3471 | */ | |
3472 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
3473 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
3474 | if (!kf_ops) { | |
3475 | cgroup_exit_cftypes(cfts); | |
3476 | return -ENOMEM; | |
3477 | } | |
3478 | kf_ops->atomic_write_len = cft->max_write_len; | |
3479 | } | |
8e3f6541 | 3480 | |
2bd59d48 | 3481 | cft->kf_ops = kf_ops; |
2bb566cb | 3482 | cft->ss = ss; |
2bd59d48 | 3483 | } |
2bb566cb | 3484 | |
2bd59d48 | 3485 | return 0; |
2da440a2 TH |
3486 | } |
3487 | ||
21a2d343 TH |
3488 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
3489 | { | |
01f6474c | 3490 | lockdep_assert_held(&cgroup_mutex); |
21a2d343 TH |
3491 | |
3492 | if (!cfts || !cfts[0].ss) | |
3493 | return -ENOENT; | |
3494 | ||
3495 | list_del(&cfts->node); | |
3496 | cgroup_apply_cftypes(cfts, false); | |
3497 | cgroup_exit_cftypes(cfts); | |
3498 | return 0; | |
8e3f6541 | 3499 | } |
8e3f6541 | 3500 | |
79578621 TH |
3501 | /** |
3502 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
3503 | * @cfts: zero-length name terminated array of cftypes |
3504 | * | |
2bb566cb TH |
3505 | * Unregister @cfts. Files described by @cfts are removed from all |
3506 | * existing cgroups and all future cgroups won't have them either. This | |
3507 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
3508 | * |
3509 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 3510 | * registered. |
79578621 | 3511 | */ |
2bb566cb | 3512 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 | 3513 | { |
21a2d343 | 3514 | int ret; |
79578621 | 3515 | |
01f6474c | 3516 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3517 | ret = cgroup_rm_cftypes_locked(cfts); |
01f6474c | 3518 | mutex_unlock(&cgroup_mutex); |
21a2d343 | 3519 | return ret; |
80b13586 TH |
3520 | } |
3521 | ||
8e3f6541 TH |
3522 | /** |
3523 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
3524 | * @ss: target cgroup subsystem | |
3525 | * @cfts: zero-length name terminated array of cftypes | |
3526 | * | |
3527 | * Register @cfts to @ss. Files described by @cfts are created for all | |
3528 | * existing cgroups to which @ss is attached and all future cgroups will | |
3529 | * have them too. This function can be called anytime whether @ss is | |
3530 | * attached or not. | |
3531 | * | |
3532 | * Returns 0 on successful registration, -errno on failure. Note that this | |
3533 | * function currently returns 0 as long as @cfts registration is successful | |
3534 | * even if some file creation attempts on existing cgroups fail. | |
3535 | */ | |
2cf669a5 | 3536 | static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 3537 | { |
9ccece80 | 3538 | int ret; |
8e3f6541 | 3539 | |
fc5ed1e9 | 3540 | if (!cgroup_ssid_enabled(ss->id)) |
c731ae1d LZ |
3541 | return 0; |
3542 | ||
dc5736ed LZ |
3543 | if (!cfts || cfts[0].name[0] == '\0') |
3544 | return 0; | |
2bb566cb | 3545 | |
2bd59d48 TH |
3546 | ret = cgroup_init_cftypes(ss, cfts); |
3547 | if (ret) | |
3548 | return ret; | |
79578621 | 3549 | |
01f6474c | 3550 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3551 | |
0adb0704 | 3552 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 3553 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 3554 | if (ret) |
21a2d343 | 3555 | cgroup_rm_cftypes_locked(cfts); |
79578621 | 3556 | |
01f6474c | 3557 | mutex_unlock(&cgroup_mutex); |
9ccece80 | 3558 | return ret; |
79578621 TH |
3559 | } |
3560 | ||
a8ddc821 TH |
3561 | /** |
3562 | * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy | |
3563 | * @ss: target cgroup subsystem | |
3564 | * @cfts: zero-length name terminated array of cftypes | |
3565 | * | |
3566 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3567 | * the default hierarchy. | |
3568 | */ | |
3569 | int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) | |
3570 | { | |
3571 | struct cftype *cft; | |
3572 | ||
3573 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
05ebb6e6 | 3574 | cft->flags |= __CFTYPE_ONLY_ON_DFL; |
a8ddc821 TH |
3575 | return cgroup_add_cftypes(ss, cfts); |
3576 | } | |
3577 | ||
3578 | /** | |
3579 | * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies | |
3580 | * @ss: target cgroup subsystem | |
3581 | * @cfts: zero-length name terminated array of cftypes | |
3582 | * | |
3583 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3584 | * the legacy hierarchies. | |
3585 | */ | |
2cf669a5 TH |
3586 | int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
3587 | { | |
a8ddc821 TH |
3588 | struct cftype *cft; |
3589 | ||
e4b7037c TH |
3590 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) |
3591 | cft->flags |= __CFTYPE_NOT_ON_DFL; | |
2cf669a5 TH |
3592 | return cgroup_add_cftypes(ss, cfts); |
3593 | } | |
3594 | ||
34c06254 TH |
3595 | /** |
3596 | * cgroup_file_notify - generate a file modified event for a cgroup_file | |
3597 | * @cfile: target cgroup_file | |
3598 | * | |
3599 | * @cfile must have been obtained by setting cftype->file_offset. | |
3600 | */ | |
3601 | void cgroup_file_notify(struct cgroup_file *cfile) | |
3602 | { | |
3603 | unsigned long flags; | |
3604 | ||
3605 | spin_lock_irqsave(&cgroup_file_kn_lock, flags); | |
3606 | if (cfile->kn) | |
3607 | kernfs_notify(cfile->kn); | |
3608 | spin_unlock_irqrestore(&cgroup_file_kn_lock, flags); | |
3609 | } | |
3610 | ||
a043e3b2 LZ |
3611 | /** |
3612 | * cgroup_task_count - count the number of tasks in a cgroup. | |
3613 | * @cgrp: the cgroup in question | |
3614 | * | |
3615 | * Return the number of tasks in the cgroup. | |
3616 | */ | |
07bc356e | 3617 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
3618 | { |
3619 | int count = 0; | |
69d0206c | 3620 | struct cgrp_cset_link *link; |
817929ec | 3621 | |
f0d9a5f1 | 3622 | spin_lock_bh(&css_set_lock); |
69d0206c TH |
3623 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
3624 | count += atomic_read(&link->cset->refcount); | |
f0d9a5f1 | 3625 | spin_unlock_bh(&css_set_lock); |
bbcb81d0 PM |
3626 | return count; |
3627 | } | |
3628 | ||
53fa5261 | 3629 | /** |
492eb21b | 3630 | * css_next_child - find the next child of a given css |
c2931b70 TH |
3631 | * @pos: the current position (%NULL to initiate traversal) |
3632 | * @parent: css whose children to walk | |
53fa5261 | 3633 | * |
c2931b70 | 3634 | * This function returns the next child of @parent and should be called |
87fb54f1 | 3635 | * under either cgroup_mutex or RCU read lock. The only requirement is |
c2931b70 TH |
3636 | * that @parent and @pos are accessible. The next sibling is guaranteed to |
3637 | * be returned regardless of their states. | |
3638 | * | |
3639 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3640 | * css which finished ->css_online() is guaranteed to be visible in the | |
3641 | * future iterations and will stay visible until the last reference is put. | |
3642 | * A css which hasn't finished ->css_online() or already finished | |
3643 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3644 | * responsibility to synchronize against on/offlining. | |
53fa5261 | 3645 | */ |
c2931b70 TH |
3646 | struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
3647 | struct cgroup_subsys_state *parent) | |
53fa5261 | 3648 | { |
c2931b70 | 3649 | struct cgroup_subsys_state *next; |
53fa5261 | 3650 | |
8353da1f | 3651 | cgroup_assert_mutex_or_rcu_locked(); |
53fa5261 TH |
3652 | |
3653 | /* | |
de3f0341 TH |
3654 | * @pos could already have been unlinked from the sibling list. |
3655 | * Once a cgroup is removed, its ->sibling.next is no longer | |
3656 | * updated when its next sibling changes. CSS_RELEASED is set when | |
3657 | * @pos is taken off list, at which time its next pointer is valid, | |
3658 | * and, as releases are serialized, the one pointed to by the next | |
3659 | * pointer is guaranteed to not have started release yet. This | |
3660 | * implies that if we observe !CSS_RELEASED on @pos in this RCU | |
3661 | * critical section, the one pointed to by its next pointer is | |
3662 | * guaranteed to not have finished its RCU grace period even if we | |
3663 | * have dropped rcu_read_lock() inbetween iterations. | |
3b287a50 | 3664 | * |
de3f0341 TH |
3665 | * If @pos has CSS_RELEASED set, its next pointer can't be |
3666 | * dereferenced; however, as each css is given a monotonically | |
3667 | * increasing unique serial number and always appended to the | |
3668 | * sibling list, the next one can be found by walking the parent's | |
3669 | * children until the first css with higher serial number than | |
3670 | * @pos's. While this path can be slower, it happens iff iteration | |
3671 | * races against release and the race window is very small. | |
53fa5261 | 3672 | */ |
3b287a50 | 3673 | if (!pos) { |
c2931b70 TH |
3674 | next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling); |
3675 | } else if (likely(!(pos->flags & CSS_RELEASED))) { | |
3676 | next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling); | |
3b287a50 | 3677 | } else { |
c2931b70 | 3678 | list_for_each_entry_rcu(next, &parent->children, sibling) |
3b287a50 TH |
3679 | if (next->serial_nr > pos->serial_nr) |
3680 | break; | |
53fa5261 TH |
3681 | } |
3682 | ||
3b281afb TH |
3683 | /* |
3684 | * @next, if not pointing to the head, can be dereferenced and is | |
c2931b70 | 3685 | * the next sibling. |
3b281afb | 3686 | */ |
c2931b70 TH |
3687 | if (&next->sibling != &parent->children) |
3688 | return next; | |
3b281afb | 3689 | return NULL; |
53fa5261 | 3690 | } |
53fa5261 | 3691 | |
574bd9f7 | 3692 | /** |
492eb21b | 3693 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 3694 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3695 | * @root: css whose descendants to walk |
574bd9f7 | 3696 | * |
492eb21b | 3697 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
3698 | * to visit for pre-order traversal of @root's descendants. @root is |
3699 | * included in the iteration and the first node to be visited. | |
75501a6d | 3700 | * |
87fb54f1 TH |
3701 | * While this function requires cgroup_mutex or RCU read locking, it |
3702 | * doesn't require the whole traversal to be contained in a single critical | |
3703 | * section. This function will return the correct next descendant as long | |
3704 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
c2931b70 TH |
3705 | * |
3706 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3707 | * css which finished ->css_online() is guaranteed to be visible in the | |
3708 | * future iterations and will stay visible until the last reference is put. | |
3709 | * A css which hasn't finished ->css_online() or already finished | |
3710 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3711 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3712 | */ |
492eb21b TH |
3713 | struct cgroup_subsys_state * |
3714 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
3715 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3716 | { |
492eb21b | 3717 | struct cgroup_subsys_state *next; |
574bd9f7 | 3718 | |
8353da1f | 3719 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3720 | |
bd8815a6 | 3721 | /* if first iteration, visit @root */ |
7805d000 | 3722 | if (!pos) |
bd8815a6 | 3723 | return root; |
574bd9f7 TH |
3724 | |
3725 | /* visit the first child if exists */ | |
492eb21b | 3726 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
3727 | if (next) |
3728 | return next; | |
3729 | ||
3730 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b | 3731 | while (pos != root) { |
5c9d535b | 3732 | next = css_next_child(pos, pos->parent); |
75501a6d | 3733 | if (next) |
574bd9f7 | 3734 | return next; |
5c9d535b | 3735 | pos = pos->parent; |
7805d000 | 3736 | } |
574bd9f7 TH |
3737 | |
3738 | return NULL; | |
3739 | } | |
574bd9f7 | 3740 | |
12a9d2fe | 3741 | /** |
492eb21b TH |
3742 | * css_rightmost_descendant - return the rightmost descendant of a css |
3743 | * @pos: css of interest | |
12a9d2fe | 3744 | * |
492eb21b TH |
3745 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
3746 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 3747 | * subtree of @pos. |
75501a6d | 3748 | * |
87fb54f1 TH |
3749 | * While this function requires cgroup_mutex or RCU read locking, it |
3750 | * doesn't require the whole traversal to be contained in a single critical | |
3751 | * section. This function will return the correct rightmost descendant as | |
3752 | * long as @pos is accessible. | |
12a9d2fe | 3753 | */ |
492eb21b TH |
3754 | struct cgroup_subsys_state * |
3755 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 3756 | { |
492eb21b | 3757 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 3758 | |
8353da1f | 3759 | cgroup_assert_mutex_or_rcu_locked(); |
12a9d2fe TH |
3760 | |
3761 | do { | |
3762 | last = pos; | |
3763 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3764 | pos = NULL; | |
492eb21b | 3765 | css_for_each_child(tmp, last) |
12a9d2fe TH |
3766 | pos = tmp; |
3767 | } while (pos); | |
3768 | ||
3769 | return last; | |
3770 | } | |
12a9d2fe | 3771 | |
492eb21b TH |
3772 | static struct cgroup_subsys_state * |
3773 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 3774 | { |
492eb21b | 3775 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
3776 | |
3777 | do { | |
3778 | last = pos; | |
492eb21b | 3779 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
3780 | } while (pos); |
3781 | ||
3782 | return last; | |
3783 | } | |
3784 | ||
3785 | /** | |
492eb21b | 3786 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 3787 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3788 | * @root: css whose descendants to walk |
574bd9f7 | 3789 | * |
492eb21b | 3790 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
3791 | * to visit for post-order traversal of @root's descendants. @root is |
3792 | * included in the iteration and the last node to be visited. | |
75501a6d | 3793 | * |
87fb54f1 TH |
3794 | * While this function requires cgroup_mutex or RCU read locking, it |
3795 | * doesn't require the whole traversal to be contained in a single critical | |
3796 | * section. This function will return the correct next descendant as long | |
3797 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
3798 | * @cgroup. | |
c2931b70 TH |
3799 | * |
3800 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3801 | * css which finished ->css_online() is guaranteed to be visible in the | |
3802 | * future iterations and will stay visible until the last reference is put. | |
3803 | * A css which hasn't finished ->css_online() or already finished | |
3804 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3805 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3806 | */ |
492eb21b TH |
3807 | struct cgroup_subsys_state * |
3808 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
3809 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3810 | { |
492eb21b | 3811 | struct cgroup_subsys_state *next; |
574bd9f7 | 3812 | |
8353da1f | 3813 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3814 | |
58b79a91 TH |
3815 | /* if first iteration, visit leftmost descendant which may be @root */ |
3816 | if (!pos) | |
3817 | return css_leftmost_descendant(root); | |
574bd9f7 | 3818 | |
bd8815a6 TH |
3819 | /* if we visited @root, we're done */ |
3820 | if (pos == root) | |
3821 | return NULL; | |
3822 | ||
574bd9f7 | 3823 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
5c9d535b | 3824 | next = css_next_child(pos, pos->parent); |
75501a6d | 3825 | if (next) |
492eb21b | 3826 | return css_leftmost_descendant(next); |
574bd9f7 TH |
3827 | |
3828 | /* no sibling left, visit parent */ | |
5c9d535b | 3829 | return pos->parent; |
574bd9f7 | 3830 | } |
574bd9f7 | 3831 | |
f3d46500 TH |
3832 | /** |
3833 | * css_has_online_children - does a css have online children | |
3834 | * @css: the target css | |
3835 | * | |
3836 | * Returns %true if @css has any online children; otherwise, %false. This | |
3837 | * function can be called from any context but the caller is responsible | |
3838 | * for synchronizing against on/offlining as necessary. | |
3839 | */ | |
3840 | bool css_has_online_children(struct cgroup_subsys_state *css) | |
cbc125ef | 3841 | { |
f3d46500 TH |
3842 | struct cgroup_subsys_state *child; |
3843 | bool ret = false; | |
cbc125ef TH |
3844 | |
3845 | rcu_read_lock(); | |
f3d46500 | 3846 | css_for_each_child(child, css) { |
99bae5f9 | 3847 | if (child->flags & CSS_ONLINE) { |
f3d46500 TH |
3848 | ret = true; |
3849 | break; | |
cbc125ef TH |
3850 | } |
3851 | } | |
3852 | rcu_read_unlock(); | |
f3d46500 | 3853 | return ret; |
574bd9f7 | 3854 | } |
574bd9f7 | 3855 | |
0942eeee | 3856 | /** |
ecb9d535 | 3857 | * css_task_iter_advance_css_set - advance a task itererator to the next css_set |
0942eeee TH |
3858 | * @it: the iterator to advance |
3859 | * | |
3860 | * Advance @it to the next css_set to walk. | |
d515876e | 3861 | */ |
ecb9d535 | 3862 | static void css_task_iter_advance_css_set(struct css_task_iter *it) |
d515876e | 3863 | { |
0f0a2b4f | 3864 | struct list_head *l = it->cset_pos; |
d515876e TH |
3865 | struct cgrp_cset_link *link; |
3866 | struct css_set *cset; | |
3867 | ||
f0d9a5f1 | 3868 | lockdep_assert_held(&css_set_lock); |
ed27b9f7 | 3869 | |
d515876e TH |
3870 | /* Advance to the next non-empty css_set */ |
3871 | do { | |
3872 | l = l->next; | |
0f0a2b4f TH |
3873 | if (l == it->cset_head) { |
3874 | it->cset_pos = NULL; | |
ecb9d535 | 3875 | it->task_pos = NULL; |
d515876e TH |
3876 | return; |
3877 | } | |
3ebb2b6e TH |
3878 | |
3879 | if (it->ss) { | |
3880 | cset = container_of(l, struct css_set, | |
3881 | e_cset_node[it->ss->id]); | |
3882 | } else { | |
3883 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
3884 | cset = link->cset; | |
3885 | } | |
0de0942d | 3886 | } while (!css_set_populated(cset)); |
c7561128 | 3887 | |
0f0a2b4f | 3888 | it->cset_pos = l; |
c7561128 TH |
3889 | |
3890 | if (!list_empty(&cset->tasks)) | |
0f0a2b4f | 3891 | it->task_pos = cset->tasks.next; |
c7561128 | 3892 | else |
0f0a2b4f TH |
3893 | it->task_pos = cset->mg_tasks.next; |
3894 | ||
3895 | it->tasks_head = &cset->tasks; | |
3896 | it->mg_tasks_head = &cset->mg_tasks; | |
ed27b9f7 TH |
3897 | |
3898 | /* | |
3899 | * We don't keep css_sets locked across iteration steps and thus | |
3900 | * need to take steps to ensure that iteration can be resumed after | |
3901 | * the lock is re-acquired. Iteration is performed at two levels - | |
3902 | * css_sets and tasks in them. | |
3903 | * | |
3904 | * Once created, a css_set never leaves its cgroup lists, so a | |
3905 | * pinned css_set is guaranteed to stay put and we can resume | |
3906 | * iteration afterwards. | |
3907 | * | |
3908 | * Tasks may leave @cset across iteration steps. This is resolved | |
3909 | * by registering each iterator with the css_set currently being | |
3910 | * walked and making css_set_move_task() advance iterators whose | |
3911 | * next task is leaving. | |
3912 | */ | |
3913 | if (it->cur_cset) { | |
3914 | list_del(&it->iters_node); | |
3915 | put_css_set_locked(it->cur_cset); | |
3916 | } | |
3917 | get_css_set(cset); | |
3918 | it->cur_cset = cset; | |
3919 | list_add(&it->iters_node, &cset->task_iters); | |
d515876e TH |
3920 | } |
3921 | ||
ecb9d535 TH |
3922 | static void css_task_iter_advance(struct css_task_iter *it) |
3923 | { | |
3924 | struct list_head *l = it->task_pos; | |
3925 | ||
f0d9a5f1 | 3926 | lockdep_assert_held(&css_set_lock); |
ecb9d535 TH |
3927 | WARN_ON_ONCE(!l); |
3928 | ||
3929 | /* | |
3930 | * Advance iterator to find next entry. cset->tasks is consumed | |
3931 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
3932 | * next cset. | |
3933 | */ | |
3934 | l = l->next; | |
3935 | ||
3936 | if (l == it->tasks_head) | |
3937 | l = it->mg_tasks_head->next; | |
3938 | ||
3939 | if (l == it->mg_tasks_head) | |
3940 | css_task_iter_advance_css_set(it); | |
3941 | else | |
3942 | it->task_pos = l; | |
3943 | } | |
3944 | ||
0942eeee | 3945 | /** |
72ec7029 TH |
3946 | * css_task_iter_start - initiate task iteration |
3947 | * @css: the css to walk tasks of | |
0942eeee TH |
3948 | * @it: the task iterator to use |
3949 | * | |
72ec7029 TH |
3950 | * Initiate iteration through the tasks of @css. The caller can call |
3951 | * css_task_iter_next() to walk through the tasks until the function | |
3952 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
3953 | * called. | |
0942eeee | 3954 | */ |
72ec7029 TH |
3955 | void css_task_iter_start(struct cgroup_subsys_state *css, |
3956 | struct css_task_iter *it) | |
817929ec | 3957 | { |
56fde9e0 TH |
3958 | /* no one should try to iterate before mounting cgroups */ |
3959 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 3960 | |
ed27b9f7 TH |
3961 | memset(it, 0, sizeof(*it)); |
3962 | ||
f0d9a5f1 | 3963 | spin_lock_bh(&css_set_lock); |
c59cd3d8 | 3964 | |
3ebb2b6e TH |
3965 | it->ss = css->ss; |
3966 | ||
3967 | if (it->ss) | |
3968 | it->cset_pos = &css->cgroup->e_csets[css->ss->id]; | |
3969 | else | |
3970 | it->cset_pos = &css->cgroup->cset_links; | |
3971 | ||
0f0a2b4f | 3972 | it->cset_head = it->cset_pos; |
c59cd3d8 | 3973 | |
ecb9d535 | 3974 | css_task_iter_advance_css_set(it); |
ed27b9f7 | 3975 | |
f0d9a5f1 | 3976 | spin_unlock_bh(&css_set_lock); |
817929ec PM |
3977 | } |
3978 | ||
0942eeee | 3979 | /** |
72ec7029 | 3980 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
3981 | * @it: the task iterator being iterated |
3982 | * | |
3983 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
3984 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
3985 | * reaches the end. | |
0942eeee | 3986 | */ |
72ec7029 | 3987 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec | 3988 | { |
d5745675 | 3989 | if (it->cur_task) { |
ed27b9f7 | 3990 | put_task_struct(it->cur_task); |
d5745675 TH |
3991 | it->cur_task = NULL; |
3992 | } | |
ed27b9f7 | 3993 | |
f0d9a5f1 | 3994 | spin_lock_bh(&css_set_lock); |
ed27b9f7 | 3995 | |
d5745675 TH |
3996 | if (it->task_pos) { |
3997 | it->cur_task = list_entry(it->task_pos, struct task_struct, | |
3998 | cg_list); | |
3999 | get_task_struct(it->cur_task); | |
4000 | css_task_iter_advance(it); | |
4001 | } | |
ed27b9f7 | 4002 | |
f0d9a5f1 | 4003 | spin_unlock_bh(&css_set_lock); |
ed27b9f7 TH |
4004 | |
4005 | return it->cur_task; | |
817929ec PM |
4006 | } |
4007 | ||
0942eeee | 4008 | /** |
72ec7029 | 4009 | * css_task_iter_end - finish task iteration |
0942eeee TH |
4010 | * @it: the task iterator to finish |
4011 | * | |
72ec7029 | 4012 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 4013 | */ |
72ec7029 | 4014 | void css_task_iter_end(struct css_task_iter *it) |
31a7df01 | 4015 | { |
ed27b9f7 | 4016 | if (it->cur_cset) { |
f0d9a5f1 | 4017 | spin_lock_bh(&css_set_lock); |
ed27b9f7 TH |
4018 | list_del(&it->iters_node); |
4019 | put_css_set_locked(it->cur_cset); | |
f0d9a5f1 | 4020 | spin_unlock_bh(&css_set_lock); |
ed27b9f7 TH |
4021 | } |
4022 | ||
4023 | if (it->cur_task) | |
4024 | put_task_struct(it->cur_task); | |
31a7df01 CW |
4025 | } |
4026 | ||
4027 | /** | |
8cc99345 TH |
4028 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
4029 | * @to: cgroup to which the tasks will be moved | |
4030 | * @from: cgroup in which the tasks currently reside | |
31a7df01 | 4031 | * |
eaf797ab TH |
4032 | * Locking rules between cgroup_post_fork() and the migration path |
4033 | * guarantee that, if a task is forking while being migrated, the new child | |
4034 | * is guaranteed to be either visible in the source cgroup after the | |
4035 | * parent's migration is complete or put into the target cgroup. No task | |
4036 | * can slip out of migration through forking. | |
31a7df01 | 4037 | */ |
8cc99345 | 4038 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
31a7df01 | 4039 | { |
952aaa12 TH |
4040 | LIST_HEAD(preloaded_csets); |
4041 | struct cgrp_cset_link *link; | |
72ec7029 | 4042 | struct css_task_iter it; |
e406d1cf | 4043 | struct task_struct *task; |
952aaa12 | 4044 | int ret; |
31a7df01 | 4045 | |
952aaa12 | 4046 | mutex_lock(&cgroup_mutex); |
31a7df01 | 4047 | |
952aaa12 | 4048 | /* all tasks in @from are being moved, all csets are source */ |
f0d9a5f1 | 4049 | spin_lock_bh(&css_set_lock); |
952aaa12 TH |
4050 | list_for_each_entry(link, &from->cset_links, cset_link) |
4051 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets); | |
f0d9a5f1 | 4052 | spin_unlock_bh(&css_set_lock); |
31a7df01 | 4053 | |
952aaa12 TH |
4054 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets); |
4055 | if (ret) | |
4056 | goto out_err; | |
8cc99345 | 4057 | |
952aaa12 | 4058 | /* |
2cfa2b19 | 4059 | * Migrate tasks one-by-one until @from is empty. This fails iff |
952aaa12 TH |
4060 | * ->can_attach() fails. |
4061 | */ | |
e406d1cf | 4062 | do { |
9d800df1 | 4063 | css_task_iter_start(&from->self, &it); |
e406d1cf TH |
4064 | task = css_task_iter_next(&it); |
4065 | if (task) | |
4066 | get_task_struct(task); | |
4067 | css_task_iter_end(&it); | |
4068 | ||
4069 | if (task) { | |
9af2ec45 | 4070 | ret = cgroup_migrate(task, false, to); |
e406d1cf TH |
4071 | put_task_struct(task); |
4072 | } | |
4073 | } while (task && !ret); | |
952aaa12 TH |
4074 | out_err: |
4075 | cgroup_migrate_finish(&preloaded_csets); | |
47cfcd09 | 4076 | mutex_unlock(&cgroup_mutex); |
e406d1cf | 4077 | return ret; |
8cc99345 TH |
4078 | } |
4079 | ||
bbcb81d0 | 4080 | /* |
102a775e | 4081 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
4082 | * |
4083 | * Reading this file can return large amounts of data if a cgroup has | |
4084 | * *lots* of attached tasks. So it may need several calls to read(), | |
4085 | * but we cannot guarantee that the information we produce is correct | |
4086 | * unless we produce it entirely atomically. | |
4087 | * | |
bbcb81d0 | 4088 | */ |
bbcb81d0 | 4089 | |
24528255 LZ |
4090 | /* which pidlist file are we talking about? */ |
4091 | enum cgroup_filetype { | |
4092 | CGROUP_FILE_PROCS, | |
4093 | CGROUP_FILE_TASKS, | |
4094 | }; | |
4095 | ||
4096 | /* | |
4097 | * A pidlist is a list of pids that virtually represents the contents of one | |
4098 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
4099 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
4100 | * to the cgroup. | |
4101 | */ | |
4102 | struct cgroup_pidlist { | |
4103 | /* | |
4104 | * used to find which pidlist is wanted. doesn't change as long as | |
4105 | * this particular list stays in the list. | |
4106 | */ | |
4107 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
4108 | /* array of xids */ | |
4109 | pid_t *list; | |
4110 | /* how many elements the above list has */ | |
4111 | int length; | |
24528255 LZ |
4112 | /* each of these stored in a list by its cgroup */ |
4113 | struct list_head links; | |
4114 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
4115 | struct cgroup *owner; | |
b1a21367 TH |
4116 | /* for delayed destruction */ |
4117 | struct delayed_work destroy_dwork; | |
24528255 LZ |
4118 | }; |
4119 | ||
d1d9fd33 BB |
4120 | /* |
4121 | * The following two functions "fix" the issue where there are more pids | |
4122 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
4123 | * TODO: replace with a kernel-wide solution to this problem | |
4124 | */ | |
4125 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
4126 | static void *pidlist_allocate(int count) | |
4127 | { | |
4128 | if (PIDLIST_TOO_LARGE(count)) | |
4129 | return vmalloc(count * sizeof(pid_t)); | |
4130 | else | |
4131 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
4132 | } | |
b1a21367 | 4133 | |
d1d9fd33 BB |
4134 | static void pidlist_free(void *p) |
4135 | { | |
58794514 | 4136 | kvfree(p); |
d1d9fd33 | 4137 | } |
d1d9fd33 | 4138 | |
b1a21367 TH |
4139 | /* |
4140 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
4141 | * should be left afterwards. | |
4142 | */ | |
4143 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
4144 | { | |
4145 | struct cgroup_pidlist *l, *tmp_l; | |
4146 | ||
4147 | mutex_lock(&cgrp->pidlist_mutex); | |
4148 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
4149 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
4150 | mutex_unlock(&cgrp->pidlist_mutex); | |
4151 | ||
4152 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
4153 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
4154 | } | |
4155 | ||
4156 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
4157 | { | |
4158 | struct delayed_work *dwork = to_delayed_work(work); | |
4159 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
4160 | destroy_dwork); | |
4161 | struct cgroup_pidlist *tofree = NULL; | |
4162 | ||
4163 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
4164 | |
4165 | /* | |
04502365 TH |
4166 | * Destroy iff we didn't get queued again. The state won't change |
4167 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 4168 | */ |
04502365 | 4169 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
4170 | list_del(&l->links); |
4171 | pidlist_free(l->list); | |
4172 | put_pid_ns(l->key.ns); | |
4173 | tofree = l; | |
4174 | } | |
4175 | ||
b1a21367 TH |
4176 | mutex_unlock(&l->owner->pidlist_mutex); |
4177 | kfree(tofree); | |
4178 | } | |
4179 | ||
bbcb81d0 | 4180 | /* |
102a775e | 4181 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 4182 | * Returns the number of unique elements. |
bbcb81d0 | 4183 | */ |
6ee211ad | 4184 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 4185 | { |
102a775e | 4186 | int src, dest = 1; |
102a775e BB |
4187 | |
4188 | /* | |
4189 | * we presume the 0th element is unique, so i starts at 1. trivial | |
4190 | * edge cases first; no work needs to be done for either | |
4191 | */ | |
4192 | if (length == 0 || length == 1) | |
4193 | return length; | |
4194 | /* src and dest walk down the list; dest counts unique elements */ | |
4195 | for (src = 1; src < length; src++) { | |
4196 | /* find next unique element */ | |
4197 | while (list[src] == list[src-1]) { | |
4198 | src++; | |
4199 | if (src == length) | |
4200 | goto after; | |
4201 | } | |
4202 | /* dest always points to where the next unique element goes */ | |
4203 | list[dest] = list[src]; | |
4204 | dest++; | |
4205 | } | |
4206 | after: | |
102a775e BB |
4207 | return dest; |
4208 | } | |
4209 | ||
afb2bc14 TH |
4210 | /* |
4211 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
4212 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
4213 | * different per namespace, each namespace needs differently sorted list, | |
4214 | * making it impossible to use, for example, single rbtree of member tasks | |
4215 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
4216 | * per open file is dangerous, so cgroup had to implement shared pool of | |
4217 | * pidlists keyed by cgroup and namespace. | |
4218 | * | |
4219 | * All this extra complexity was caused by the original implementation | |
4220 | * committing to an entirely unnecessary property. In the long term, we | |
aa6ec29b TH |
4221 | * want to do away with it. Explicitly scramble sort order if on the |
4222 | * default hierarchy so that no such expectation exists in the new | |
4223 | * interface. | |
afb2bc14 TH |
4224 | * |
4225 | * Scrambling is done by swapping every two consecutive bits, which is | |
4226 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
4227 | */ | |
4228 | static pid_t pid_fry(pid_t pid) | |
4229 | { | |
4230 | unsigned a = pid & 0x55555555; | |
4231 | unsigned b = pid & 0xAAAAAAAA; | |
4232 | ||
4233 | return (a << 1) | (b >> 1); | |
4234 | } | |
4235 | ||
4236 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
4237 | { | |
aa6ec29b | 4238 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4239 | return pid_fry(pid); |
4240 | else | |
4241 | return pid; | |
4242 | } | |
4243 | ||
102a775e BB |
4244 | static int cmppid(const void *a, const void *b) |
4245 | { | |
4246 | return *(pid_t *)a - *(pid_t *)b; | |
4247 | } | |
4248 | ||
afb2bc14 TH |
4249 | static int fried_cmppid(const void *a, const void *b) |
4250 | { | |
4251 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
4252 | } | |
4253 | ||
e6b81710 TH |
4254 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
4255 | enum cgroup_filetype type) | |
4256 | { | |
4257 | struct cgroup_pidlist *l; | |
4258 | /* don't need task_nsproxy() if we're looking at ourself */ | |
4259 | struct pid_namespace *ns = task_active_pid_ns(current); | |
4260 | ||
4261 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
4262 | ||
4263 | list_for_each_entry(l, &cgrp->pidlists, links) | |
4264 | if (l->key.type == type && l->key.ns == ns) | |
4265 | return l; | |
4266 | return NULL; | |
4267 | } | |
4268 | ||
72a8cb30 BB |
4269 | /* |
4270 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
4271 | * returns with the lock on that pidlist already held, and takes care | |
4272 | * of the use count, or returns NULL with no locks held if we're out of | |
4273 | * memory. | |
4274 | */ | |
e6b81710 TH |
4275 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
4276 | enum cgroup_filetype type) | |
72a8cb30 BB |
4277 | { |
4278 | struct cgroup_pidlist *l; | |
b70cc5fd | 4279 | |
e6b81710 TH |
4280 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4281 | ||
4282 | l = cgroup_pidlist_find(cgrp, type); | |
4283 | if (l) | |
4284 | return l; | |
4285 | ||
72a8cb30 | 4286 | /* entry not found; create a new one */ |
f4f4be2b | 4287 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 4288 | if (!l) |
72a8cb30 | 4289 | return l; |
e6b81710 | 4290 | |
b1a21367 | 4291 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 4292 | l->key.type = type; |
e6b81710 TH |
4293 | /* don't need task_nsproxy() if we're looking at ourself */ |
4294 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
4295 | l->owner = cgrp; |
4296 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
4297 | return l; |
4298 | } | |
4299 | ||
102a775e BB |
4300 | /* |
4301 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
4302 | */ | |
72a8cb30 BB |
4303 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
4304 | struct cgroup_pidlist **lp) | |
102a775e BB |
4305 | { |
4306 | pid_t *array; | |
4307 | int length; | |
4308 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 4309 | struct css_task_iter it; |
817929ec | 4310 | struct task_struct *tsk; |
102a775e BB |
4311 | struct cgroup_pidlist *l; |
4312 | ||
4bac00d1 TH |
4313 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4314 | ||
102a775e BB |
4315 | /* |
4316 | * If cgroup gets more users after we read count, we won't have | |
4317 | * enough space - tough. This race is indistinguishable to the | |
4318 | * caller from the case that the additional cgroup users didn't | |
4319 | * show up until sometime later on. | |
4320 | */ | |
4321 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 4322 | array = pidlist_allocate(length); |
102a775e BB |
4323 | if (!array) |
4324 | return -ENOMEM; | |
4325 | /* now, populate the array */ | |
9d800df1 | 4326 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4327 | while ((tsk = css_task_iter_next(&it))) { |
102a775e | 4328 | if (unlikely(n == length)) |
817929ec | 4329 | break; |
102a775e | 4330 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
4331 | if (type == CGROUP_FILE_PROCS) |
4332 | pid = task_tgid_vnr(tsk); | |
4333 | else | |
4334 | pid = task_pid_vnr(tsk); | |
102a775e BB |
4335 | if (pid > 0) /* make sure to only use valid results */ |
4336 | array[n++] = pid; | |
817929ec | 4337 | } |
72ec7029 | 4338 | css_task_iter_end(&it); |
102a775e BB |
4339 | length = n; |
4340 | /* now sort & (if procs) strip out duplicates */ | |
aa6ec29b | 4341 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4342 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); |
4343 | else | |
4344 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 4345 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 4346 | length = pidlist_uniq(array, length); |
e6b81710 | 4347 | |
e6b81710 | 4348 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 4349 | if (!l) { |
d1d9fd33 | 4350 | pidlist_free(array); |
72a8cb30 | 4351 | return -ENOMEM; |
102a775e | 4352 | } |
e6b81710 TH |
4353 | |
4354 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 4355 | pidlist_free(l->list); |
102a775e BB |
4356 | l->list = array; |
4357 | l->length = length; | |
72a8cb30 | 4358 | *lp = l; |
102a775e | 4359 | return 0; |
bbcb81d0 PM |
4360 | } |
4361 | ||
846c7bb0 | 4362 | /** |
a043e3b2 | 4363 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
4364 | * @stats: cgroupstats to fill information into |
4365 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
4366 | * been requested. | |
a043e3b2 LZ |
4367 | * |
4368 | * Build and fill cgroupstats so that taskstats can export it to user | |
4369 | * space. | |
846c7bb0 BS |
4370 | */ |
4371 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
4372 | { | |
2bd59d48 | 4373 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 4374 | struct cgroup *cgrp; |
72ec7029 | 4375 | struct css_task_iter it; |
846c7bb0 | 4376 | struct task_struct *tsk; |
33d283be | 4377 | |
2bd59d48 TH |
4378 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
4379 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
4380 | kernfs_type(kn) != KERNFS_DIR) | |
4381 | return -EINVAL; | |
4382 | ||
bad34660 LZ |
4383 | mutex_lock(&cgroup_mutex); |
4384 | ||
846c7bb0 | 4385 | /* |
2bd59d48 | 4386 | * We aren't being called from kernfs and there's no guarantee on |
ec903c0c | 4387 | * @kn->priv's validity. For this and css_tryget_online_from_dir(), |
2bd59d48 | 4388 | * @kn->priv is RCU safe. Let's do the RCU dancing. |
846c7bb0 | 4389 | */ |
2bd59d48 TH |
4390 | rcu_read_lock(); |
4391 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 4392 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 4393 | rcu_read_unlock(); |
bad34660 | 4394 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
4395 | return -ENOENT; |
4396 | } | |
bad34660 | 4397 | rcu_read_unlock(); |
846c7bb0 | 4398 | |
9d800df1 | 4399 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4400 | while ((tsk = css_task_iter_next(&it))) { |
846c7bb0 BS |
4401 | switch (tsk->state) { |
4402 | case TASK_RUNNING: | |
4403 | stats->nr_running++; | |
4404 | break; | |
4405 | case TASK_INTERRUPTIBLE: | |
4406 | stats->nr_sleeping++; | |
4407 | break; | |
4408 | case TASK_UNINTERRUPTIBLE: | |
4409 | stats->nr_uninterruptible++; | |
4410 | break; | |
4411 | case TASK_STOPPED: | |
4412 | stats->nr_stopped++; | |
4413 | break; | |
4414 | default: | |
4415 | if (delayacct_is_task_waiting_on_io(tsk)) | |
4416 | stats->nr_io_wait++; | |
4417 | break; | |
4418 | } | |
4419 | } | |
72ec7029 | 4420 | css_task_iter_end(&it); |
846c7bb0 | 4421 | |
bad34660 | 4422 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 4423 | return 0; |
846c7bb0 BS |
4424 | } |
4425 | ||
8f3ff208 | 4426 | |
bbcb81d0 | 4427 | /* |
102a775e | 4428 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 4429 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 4430 | * in the cgroup->l->list array. |
bbcb81d0 | 4431 | */ |
cc31edce | 4432 | |
102a775e | 4433 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 4434 | { |
cc31edce PM |
4435 | /* |
4436 | * Initially we receive a position value that corresponds to | |
4437 | * one more than the last pid shown (or 0 on the first call or | |
4438 | * after a seek to the start). Use a binary-search to find the | |
4439 | * next pid to display, if any | |
4440 | */ | |
2bd59d48 | 4441 | struct kernfs_open_file *of = s->private; |
7da11279 | 4442 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 4443 | struct cgroup_pidlist *l; |
7da11279 | 4444 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 4445 | int index = 0, pid = *pos; |
4bac00d1 TH |
4446 | int *iter, ret; |
4447 | ||
4448 | mutex_lock(&cgrp->pidlist_mutex); | |
4449 | ||
4450 | /* | |
5d22444f | 4451 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 4452 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 4453 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
4454 | * could already have been destroyed. |
4455 | */ | |
5d22444f TH |
4456 | if (of->priv) |
4457 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
4458 | |
4459 | /* | |
4460 | * Either this is the first start() after open or the matching | |
4461 | * pidlist has been destroyed inbetween. Create a new one. | |
4462 | */ | |
5d22444f TH |
4463 | if (!of->priv) { |
4464 | ret = pidlist_array_load(cgrp, type, | |
4465 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
4466 | if (ret) |
4467 | return ERR_PTR(ret); | |
4468 | } | |
5d22444f | 4469 | l = of->priv; |
cc31edce | 4470 | |
cc31edce | 4471 | if (pid) { |
102a775e | 4472 | int end = l->length; |
20777766 | 4473 | |
cc31edce PM |
4474 | while (index < end) { |
4475 | int mid = (index + end) / 2; | |
afb2bc14 | 4476 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
4477 | index = mid; |
4478 | break; | |
afb2bc14 | 4479 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
4480 | index = mid + 1; |
4481 | else | |
4482 | end = mid; | |
4483 | } | |
4484 | } | |
4485 | /* If we're off the end of the array, we're done */ | |
102a775e | 4486 | if (index >= l->length) |
cc31edce PM |
4487 | return NULL; |
4488 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 4489 | iter = l->list + index; |
afb2bc14 | 4490 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
4491 | return iter; |
4492 | } | |
4493 | ||
102a775e | 4494 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 4495 | { |
2bd59d48 | 4496 | struct kernfs_open_file *of = s->private; |
5d22444f | 4497 | struct cgroup_pidlist *l = of->priv; |
62236858 | 4498 | |
5d22444f TH |
4499 | if (l) |
4500 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 4501 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 4502 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
4503 | } |
4504 | ||
102a775e | 4505 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 4506 | { |
2bd59d48 | 4507 | struct kernfs_open_file *of = s->private; |
5d22444f | 4508 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
4509 | pid_t *p = v; |
4510 | pid_t *end = l->list + l->length; | |
cc31edce PM |
4511 | /* |
4512 | * Advance to the next pid in the array. If this goes off the | |
4513 | * end, we're done | |
4514 | */ | |
4515 | p++; | |
4516 | if (p >= end) { | |
4517 | return NULL; | |
4518 | } else { | |
7da11279 | 4519 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
4520 | return p; |
4521 | } | |
4522 | } | |
4523 | ||
102a775e | 4524 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce | 4525 | { |
94ff212d JP |
4526 | seq_printf(s, "%d\n", *(int *)v); |
4527 | ||
4528 | return 0; | |
cc31edce | 4529 | } |
bbcb81d0 | 4530 | |
182446d0 TH |
4531 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
4532 | struct cftype *cft) | |
81a6a5cd | 4533 | { |
182446d0 | 4534 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
4535 | } |
4536 | ||
182446d0 TH |
4537 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
4538 | struct cftype *cft, u64 val) | |
6379c106 | 4539 | { |
6379c106 | 4540 | if (val) |
182446d0 | 4541 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 4542 | else |
182446d0 | 4543 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
4544 | return 0; |
4545 | } | |
4546 | ||
182446d0 TH |
4547 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
4548 | struct cftype *cft) | |
97978e6d | 4549 | { |
182446d0 | 4550 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4551 | } |
4552 | ||
182446d0 TH |
4553 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
4554 | struct cftype *cft, u64 val) | |
97978e6d DL |
4555 | { |
4556 | if (val) | |
182446d0 | 4557 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 4558 | else |
182446d0 | 4559 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4560 | return 0; |
4561 | } | |
4562 | ||
a14c6874 TH |
4563 | /* cgroup core interface files for the default hierarchy */ |
4564 | static struct cftype cgroup_dfl_base_files[] = { | |
81a6a5cd | 4565 | { |
d5c56ced | 4566 | .name = "cgroup.procs", |
6f60eade | 4567 | .file_offset = offsetof(struct cgroup, procs_file), |
6612f05b TH |
4568 | .seq_start = cgroup_pidlist_start, |
4569 | .seq_next = cgroup_pidlist_next, | |
4570 | .seq_stop = cgroup_pidlist_stop, | |
4571 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4572 | .private = CGROUP_FILE_PROCS, |
acbef755 | 4573 | .write = cgroup_procs_write, |
102a775e | 4574 | }, |
f8f22e53 TH |
4575 | { |
4576 | .name = "cgroup.controllers", | |
f8f22e53 TH |
4577 | .seq_show = cgroup_controllers_show, |
4578 | }, | |
4579 | { | |
4580 | .name = "cgroup.subtree_control", | |
f8f22e53 | 4581 | .seq_show = cgroup_subtree_control_show, |
451af504 | 4582 | .write = cgroup_subtree_control_write, |
f8f22e53 | 4583 | }, |
842b597e | 4584 | { |
4a07c222 | 4585 | .name = "cgroup.events", |
a14c6874 | 4586 | .flags = CFTYPE_NOT_ON_ROOT, |
6f60eade | 4587 | .file_offset = offsetof(struct cgroup, events_file), |
4a07c222 | 4588 | .seq_show = cgroup_events_show, |
842b597e | 4589 | }, |
a14c6874 TH |
4590 | { } /* terminate */ |
4591 | }; | |
d5c56ced | 4592 | |
a14c6874 TH |
4593 | /* cgroup core interface files for the legacy hierarchies */ |
4594 | static struct cftype cgroup_legacy_base_files[] = { | |
4595 | { | |
4596 | .name = "cgroup.procs", | |
4597 | .seq_start = cgroup_pidlist_start, | |
4598 | .seq_next = cgroup_pidlist_next, | |
4599 | .seq_stop = cgroup_pidlist_stop, | |
4600 | .seq_show = cgroup_pidlist_show, | |
4601 | .private = CGROUP_FILE_PROCS, | |
4602 | .write = cgroup_procs_write, | |
a14c6874 TH |
4603 | }, |
4604 | { | |
4605 | .name = "cgroup.clone_children", | |
4606 | .read_u64 = cgroup_clone_children_read, | |
4607 | .write_u64 = cgroup_clone_children_write, | |
4608 | }, | |
4609 | { | |
4610 | .name = "cgroup.sane_behavior", | |
4611 | .flags = CFTYPE_ONLY_ON_ROOT, | |
4612 | .seq_show = cgroup_sane_behavior_show, | |
4613 | }, | |
d5c56ced TH |
4614 | { |
4615 | .name = "tasks", | |
6612f05b TH |
4616 | .seq_start = cgroup_pidlist_start, |
4617 | .seq_next = cgroup_pidlist_next, | |
4618 | .seq_stop = cgroup_pidlist_stop, | |
4619 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4620 | .private = CGROUP_FILE_TASKS, |
acbef755 | 4621 | .write = cgroup_tasks_write, |
d5c56ced TH |
4622 | }, |
4623 | { | |
4624 | .name = "notify_on_release", | |
d5c56ced TH |
4625 | .read_u64 = cgroup_read_notify_on_release, |
4626 | .write_u64 = cgroup_write_notify_on_release, | |
4627 | }, | |
6e6ff25b TH |
4628 | { |
4629 | .name = "release_agent", | |
a14c6874 | 4630 | .flags = CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 4631 | .seq_show = cgroup_release_agent_show, |
451af504 | 4632 | .write = cgroup_release_agent_write, |
5f469907 | 4633 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 4634 | }, |
db0416b6 | 4635 | { } /* terminate */ |
bbcb81d0 PM |
4636 | }; |
4637 | ||
0c21ead1 TH |
4638 | /* |
4639 | * css destruction is four-stage process. | |
4640 | * | |
4641 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
4642 | * Implemented in kill_css(). | |
4643 | * | |
4644 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
ec903c0c TH |
4645 | * and thus css_tryget_online() is guaranteed to fail, the css can be |
4646 | * offlined by invoking offline_css(). After offlining, the base ref is | |
4647 | * put. Implemented in css_killed_work_fn(). | |
0c21ead1 TH |
4648 | * |
4649 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
4650 | * accessors are inside RCU read sections. css_release() schedules the | |
4651 | * RCU callback. | |
4652 | * | |
4653 | * 4. After the grace period, the css can be freed. Implemented in | |
4654 | * css_free_work_fn(). | |
4655 | * | |
4656 | * It is actually hairier because both step 2 and 4 require process context | |
4657 | * and thus involve punting to css->destroy_work adding two additional | |
4658 | * steps to the already complex sequence. | |
4659 | */ | |
35ef10da | 4660 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
4661 | { |
4662 | struct cgroup_subsys_state *css = | |
35ef10da | 4663 | container_of(work, struct cgroup_subsys_state, destroy_work); |
01e58659 | 4664 | struct cgroup_subsys *ss = css->ss; |
0c21ead1 | 4665 | struct cgroup *cgrp = css->cgroup; |
48ddbe19 | 4666 | |
9a1049da TH |
4667 | percpu_ref_exit(&css->refcnt); |
4668 | ||
01e58659 | 4669 | if (ss) { |
9d755d33 | 4670 | /* css free path */ |
8bb5ef79 | 4671 | struct cgroup_subsys_state *parent = css->parent; |
01e58659 VD |
4672 | int id = css->id; |
4673 | ||
01e58659 VD |
4674 | ss->css_free(css); |
4675 | cgroup_idr_remove(&ss->css_idr, id); | |
9d755d33 | 4676 | cgroup_put(cgrp); |
8bb5ef79 TH |
4677 | |
4678 | if (parent) | |
4679 | css_put(parent); | |
9d755d33 TH |
4680 | } else { |
4681 | /* cgroup free path */ | |
4682 | atomic_dec(&cgrp->root->nr_cgrps); | |
4683 | cgroup_pidlist_destroy_all(cgrp); | |
971ff493 | 4684 | cancel_work_sync(&cgrp->release_agent_work); |
9d755d33 | 4685 | |
d51f39b0 | 4686 | if (cgroup_parent(cgrp)) { |
9d755d33 TH |
4687 | /* |
4688 | * We get a ref to the parent, and put the ref when | |
4689 | * this cgroup is being freed, so it's guaranteed | |
4690 | * that the parent won't be destroyed before its | |
4691 | * children. | |
4692 | */ | |
d51f39b0 | 4693 | cgroup_put(cgroup_parent(cgrp)); |
9d755d33 TH |
4694 | kernfs_put(cgrp->kn); |
4695 | kfree(cgrp); | |
4696 | } else { | |
4697 | /* | |
4698 | * This is root cgroup's refcnt reaching zero, | |
4699 | * which indicates that the root should be | |
4700 | * released. | |
4701 | */ | |
4702 | cgroup_destroy_root(cgrp->root); | |
4703 | } | |
4704 | } | |
48ddbe19 TH |
4705 | } |
4706 | ||
0c21ead1 | 4707 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
4708 | { |
4709 | struct cgroup_subsys_state *css = | |
0c21ead1 | 4710 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 4711 | |
35ef10da | 4712 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 4713 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
4714 | } |
4715 | ||
25e15d83 | 4716 | static void css_release_work_fn(struct work_struct *work) |
d3daf28d TH |
4717 | { |
4718 | struct cgroup_subsys_state *css = | |
25e15d83 | 4719 | container_of(work, struct cgroup_subsys_state, destroy_work); |
15a4c835 | 4720 | struct cgroup_subsys *ss = css->ss; |
9d755d33 | 4721 | struct cgroup *cgrp = css->cgroup; |
15a4c835 | 4722 | |
1fed1b2e TH |
4723 | mutex_lock(&cgroup_mutex); |
4724 | ||
de3f0341 | 4725 | css->flags |= CSS_RELEASED; |
1fed1b2e TH |
4726 | list_del_rcu(&css->sibling); |
4727 | ||
9d755d33 TH |
4728 | if (ss) { |
4729 | /* css release path */ | |
01e58659 | 4730 | cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
7d172cc8 TH |
4731 | if (ss->css_released) |
4732 | ss->css_released(css); | |
9d755d33 TH |
4733 | } else { |
4734 | /* cgroup release path */ | |
9d755d33 TH |
4735 | cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); |
4736 | cgrp->id = -1; | |
a4189487 LZ |
4737 | |
4738 | /* | |
4739 | * There are two control paths which try to determine | |
4740 | * cgroup from dentry without going through kernfs - | |
4741 | * cgroupstats_build() and css_tryget_online_from_dir(). | |
4742 | * Those are supported by RCU protecting clearing of | |
4743 | * cgrp->kn->priv backpointer. | |
4744 | */ | |
6cd0f5bb TH |
4745 | if (cgrp->kn) |
4746 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, | |
4747 | NULL); | |
9d755d33 | 4748 | } |
d3daf28d | 4749 | |
1fed1b2e TH |
4750 | mutex_unlock(&cgroup_mutex); |
4751 | ||
0c21ead1 | 4752 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
4753 | } |
4754 | ||
d3daf28d TH |
4755 | static void css_release(struct percpu_ref *ref) |
4756 | { | |
4757 | struct cgroup_subsys_state *css = | |
4758 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4759 | ||
25e15d83 TH |
4760 | INIT_WORK(&css->destroy_work, css_release_work_fn); |
4761 | queue_work(cgroup_destroy_wq, &css->destroy_work); | |
d3daf28d TH |
4762 | } |
4763 | ||
ddfcadab TH |
4764 | static void init_and_link_css(struct cgroup_subsys_state *css, |
4765 | struct cgroup_subsys *ss, struct cgroup *cgrp) | |
ddbcc7e8 | 4766 | { |
0cb51d71 TH |
4767 | lockdep_assert_held(&cgroup_mutex); |
4768 | ||
ddfcadab TH |
4769 | cgroup_get(cgrp); |
4770 | ||
d5c419b6 | 4771 | memset(css, 0, sizeof(*css)); |
bd89aabc | 4772 | css->cgroup = cgrp; |
72c97e54 | 4773 | css->ss = ss; |
d5c419b6 TH |
4774 | INIT_LIST_HEAD(&css->sibling); |
4775 | INIT_LIST_HEAD(&css->children); | |
0cb51d71 | 4776 | css->serial_nr = css_serial_nr_next++; |
aa226ff4 | 4777 | atomic_set(&css->online_cnt, 0); |
0ae78e0b | 4778 | |
d51f39b0 TH |
4779 | if (cgroup_parent(cgrp)) { |
4780 | css->parent = cgroup_css(cgroup_parent(cgrp), ss); | |
ddfcadab | 4781 | css_get(css->parent); |
ddfcadab | 4782 | } |
48ddbe19 | 4783 | |
ca8bdcaf | 4784 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
4785 | } |
4786 | ||
2a4ac633 | 4787 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 4788 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4789 | { |
623f926b | 4790 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
4791 | int ret = 0; |
4792 | ||
a31f2d3f TH |
4793 | lockdep_assert_held(&cgroup_mutex); |
4794 | ||
92fb9748 | 4795 | if (ss->css_online) |
eb95419b | 4796 | ret = ss->css_online(css); |
ae7f164a | 4797 | if (!ret) { |
eb95419b | 4798 | css->flags |= CSS_ONLINE; |
aec25020 | 4799 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
aa226ff4 TH |
4800 | |
4801 | atomic_inc(&css->online_cnt); | |
4802 | if (css->parent) | |
4803 | atomic_inc(&css->parent->online_cnt); | |
ae7f164a | 4804 | } |
b1929db4 | 4805 | return ret; |
a31f2d3f TH |
4806 | } |
4807 | ||
2a4ac633 | 4808 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 4809 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4810 | { |
623f926b | 4811 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f TH |
4812 | |
4813 | lockdep_assert_held(&cgroup_mutex); | |
4814 | ||
4815 | if (!(css->flags & CSS_ONLINE)) | |
4816 | return; | |
4817 | ||
fa06235b VD |
4818 | if (ss->css_reset) |
4819 | ss->css_reset(css); | |
4820 | ||
d7eeac19 | 4821 | if (ss->css_offline) |
eb95419b | 4822 | ss->css_offline(css); |
a31f2d3f | 4823 | |
eb95419b | 4824 | css->flags &= ~CSS_ONLINE; |
e3297803 | 4825 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL); |
f8f22e53 TH |
4826 | |
4827 | wake_up_all(&css->cgroup->offline_waitq); | |
a31f2d3f TH |
4828 | } |
4829 | ||
c81c925a | 4830 | /** |
6cd0f5bb | 4831 | * css_create - create a cgroup_subsys_state |
c81c925a TH |
4832 | * @cgrp: the cgroup new css will be associated with |
4833 | * @ss: the subsys of new css | |
4834 | * | |
4835 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
6cd0f5bb TH |
4836 | * css is online and installed in @cgrp. This function doesn't create the |
4837 | * interface files. Returns 0 on success, -errno on failure. | |
c81c925a | 4838 | */ |
6cd0f5bb TH |
4839 | static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
4840 | struct cgroup_subsys *ss) | |
c81c925a | 4841 | { |
d51f39b0 | 4842 | struct cgroup *parent = cgroup_parent(cgrp); |
1fed1b2e | 4843 | struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); |
c81c925a TH |
4844 | struct cgroup_subsys_state *css; |
4845 | int err; | |
4846 | ||
c81c925a TH |
4847 | lockdep_assert_held(&cgroup_mutex); |
4848 | ||
1fed1b2e | 4849 | css = ss->css_alloc(parent_css); |
c81c925a | 4850 | if (IS_ERR(css)) |
6cd0f5bb | 4851 | return css; |
c81c925a | 4852 | |
ddfcadab | 4853 | init_and_link_css(css, ss, cgrp); |
a2bed820 | 4854 | |
2aad2a86 | 4855 | err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); |
c81c925a | 4856 | if (err) |
3eb59ec6 | 4857 | goto err_free_css; |
c81c925a | 4858 | |
cf780b7d | 4859 | err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL); |
15a4c835 TH |
4860 | if (err < 0) |
4861 | goto err_free_percpu_ref; | |
4862 | css->id = err; | |
c81c925a | 4863 | |
15a4c835 | 4864 | /* @css is ready to be brought online now, make it visible */ |
1fed1b2e | 4865 | list_add_tail_rcu(&css->sibling, &parent_css->children); |
15a4c835 | 4866 | cgroup_idr_replace(&ss->css_idr, css, css->id); |
c81c925a TH |
4867 | |
4868 | err = online_css(css); | |
4869 | if (err) | |
1fed1b2e | 4870 | goto err_list_del; |
94419627 | 4871 | |
c81c925a | 4872 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
d51f39b0 | 4873 | cgroup_parent(parent)) { |
ed3d261b | 4874 | pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", |
a2a1f9ea | 4875 | current->comm, current->pid, ss->name); |
c81c925a | 4876 | if (!strcmp(ss->name, "memory")) |
ed3d261b | 4877 | pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n"); |
c81c925a TH |
4878 | ss->warned_broken_hierarchy = true; |
4879 | } | |
4880 | ||
6cd0f5bb | 4881 | return css; |
c81c925a | 4882 | |
1fed1b2e TH |
4883 | err_list_del: |
4884 | list_del_rcu(&css->sibling); | |
15a4c835 | 4885 | cgroup_idr_remove(&ss->css_idr, css->id); |
3eb59ec6 | 4886 | err_free_percpu_ref: |
9a1049da | 4887 | percpu_ref_exit(&css->refcnt); |
3eb59ec6 | 4888 | err_free_css: |
a2bed820 | 4889 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
6cd0f5bb | 4890 | return ERR_PTR(err); |
c81c925a TH |
4891 | } |
4892 | ||
a5bca215 | 4893 | static struct cgroup *cgroup_create(struct cgroup *parent) |
ddbcc7e8 | 4894 | { |
a5bca215 | 4895 | struct cgroup_root *root = parent->root; |
ddbcc7e8 | 4896 | struct cgroup_subsys *ss; |
a5bca215 TH |
4897 | struct cgroup *cgrp, *tcgrp; |
4898 | int level = parent->level + 1; | |
4899 | int ssid, ret; | |
ddbcc7e8 | 4900 | |
0a950f65 | 4901 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
b11cfb58 TH |
4902 | cgrp = kzalloc(sizeof(*cgrp) + |
4903 | sizeof(cgrp->ancestor_ids[0]) * (level + 1), GFP_KERNEL); | |
a5bca215 TH |
4904 | if (!cgrp) |
4905 | return ERR_PTR(-ENOMEM); | |
0ab02ca8 | 4906 | |
2aad2a86 | 4907 | ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); |
9d755d33 TH |
4908 | if (ret) |
4909 | goto out_free_cgrp; | |
4910 | ||
0ab02ca8 LZ |
4911 | /* |
4912 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
4913 | * a half-baked cgroup. | |
4914 | */ | |
cf780b7d | 4915 | cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); |
0ab02ca8 | 4916 | if (cgrp->id < 0) { |
ba0f4d76 | 4917 | ret = -ENOMEM; |
9d755d33 | 4918 | goto out_cancel_ref; |
976c06bc TH |
4919 | } |
4920 | ||
cc31edce | 4921 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4922 | |
9d800df1 | 4923 | cgrp->self.parent = &parent->self; |
ba0f4d76 | 4924 | cgrp->root = root; |
b11cfb58 TH |
4925 | cgrp->level = level; |
4926 | ||
4927 | for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) | |
4928 | cgrp->ancestor_ids[tcgrp->level] = tcgrp->id; | |
ddbcc7e8 | 4929 | |
b6abdb0e LZ |
4930 | if (notify_on_release(parent)) |
4931 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4932 | ||
2260e7fc TH |
4933 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4934 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4935 | |
0cb51d71 | 4936 | cgrp->self.serial_nr = css_serial_nr_next++; |
53fa5261 | 4937 | |
4e139afc | 4938 | /* allocation complete, commit to creation */ |
d5c419b6 | 4939 | list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children); |
3c9c825b | 4940 | atomic_inc(&root->nr_cgrps); |
59f5296b | 4941 | cgroup_get(parent); |
415cf07a | 4942 | |
0d80255e TH |
4943 | /* |
4944 | * @cgrp is now fully operational. If something fails after this | |
4945 | * point, it'll be released via the normal destruction path. | |
4946 | */ | |
6fa4918d | 4947 | cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
4e96ee8e | 4948 | |
195e9b6c | 4949 | /* create the csses */ |
5531dc91 | 4950 | do_each_subsys_mask(ss, ssid, cgroup_ss_mask(cgrp)) { |
6cd0f5bb TH |
4951 | struct cgroup_subsys_state *css; |
4952 | ||
4953 | css = css_create(cgrp, ss); | |
4954 | if (IS_ERR(css)) { | |
4955 | ret = PTR_ERR(css); | |
996cd1fb | 4956 | goto out_destroy; |
6cd0f5bb | 4957 | } |
996cd1fb | 4958 | } while_each_subsys_mask(); |
ddbcc7e8 | 4959 | |
bd53d617 TH |
4960 | /* |
4961 | * On the default hierarchy, a child doesn't automatically inherit | |
667c2491 | 4962 | * subtree_control from the parent. Each is configured manually. |
bd53d617 | 4963 | */ |
667c2491 | 4964 | if (!cgroup_on_dfl(cgrp)) { |
5531dc91 | 4965 | cgrp->subtree_control = cgroup_control(cgrp); |
8699b776 | 4966 | cgroup_refresh_subtree_ss_mask(cgrp); |
667c2491 | 4967 | } |
2bd59d48 | 4968 | |
a5bca215 TH |
4969 | return cgrp; |
4970 | ||
4971 | out_cancel_ref: | |
4972 | percpu_ref_exit(&cgrp->self.refcnt); | |
4973 | out_free_cgrp: | |
4974 | kfree(cgrp); | |
4975 | return ERR_PTR(ret); | |
4976 | out_destroy: | |
4977 | cgroup_destroy_locked(cgrp); | |
4978 | return ERR_PTR(ret); | |
4979 | } | |
4980 | ||
4981 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, | |
4982 | umode_t mode) | |
4983 | { | |
4984 | struct cgroup *parent, *cgrp; | |
4985 | struct cgroup_subsys *ss; | |
4986 | struct kernfs_node *kn; | |
4987 | int ssid, ret; | |
4988 | ||
4989 | /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */ | |
4990 | if (strchr(name, '\n')) | |
4991 | return -EINVAL; | |
4992 | ||
4993 | parent = cgroup_kn_lock_live(parent_kn); | |
4994 | if (!parent) | |
4995 | return -ENODEV; | |
4996 | ||
4997 | cgrp = cgroup_create(parent); | |
4998 | if (IS_ERR(cgrp)) { | |
4999 | ret = PTR_ERR(cgrp); | |
5000 | goto out_unlock; | |
5001 | } | |
5002 | ||
195e9b6c TH |
5003 | /* create the directory */ |
5004 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); | |
5005 | if (IS_ERR(kn)) { | |
5006 | ret = PTR_ERR(kn); | |
5007 | goto out_destroy; | |
5008 | } | |
5009 | cgrp->kn = kn; | |
5010 | ||
5011 | /* | |
5012 | * This extra ref will be put in cgroup_free_fn() and guarantees | |
5013 | * that @cgrp->kn is always accessible. | |
5014 | */ | |
5015 | kernfs_get(kn); | |
5016 | ||
5017 | ret = cgroup_kn_set_ugid(kn); | |
5018 | if (ret) | |
5019 | goto out_destroy; | |
5020 | ||
5021 | ret = css_populate_dir(&cgrp->self, NULL); | |
5022 | if (ret) | |
5023 | goto out_destroy; | |
5024 | ||
5531dc91 | 5025 | do_each_subsys_mask(ss, ssid, cgroup_control(cgrp)) { |
195e9b6c TH |
5026 | ret = css_populate_dir(cgroup_css(cgrp, ss), NULL); |
5027 | if (ret) | |
5028 | goto out_destroy; | |
5029 | } while_each_subsys_mask(); | |
5030 | ||
5031 | /* let's create and online css's */ | |
2bd59d48 | 5032 | kernfs_activate(kn); |
ddbcc7e8 | 5033 | |
ba0f4d76 TH |
5034 | ret = 0; |
5035 | goto out_unlock; | |
ddbcc7e8 | 5036 | |
a5bca215 TH |
5037 | out_destroy: |
5038 | cgroup_destroy_locked(cgrp); | |
ba0f4d76 | 5039 | out_unlock: |
a9746d8d | 5040 | cgroup_kn_unlock(parent_kn); |
ba0f4d76 | 5041 | return ret; |
ddbcc7e8 PM |
5042 | } |
5043 | ||
223dbc38 TH |
5044 | /* |
5045 | * This is called when the refcnt of a css is confirmed to be killed. | |
249f3468 TH |
5046 | * css_tryget_online() is now guaranteed to fail. Tell the subsystem to |
5047 | * initate destruction and put the css ref from kill_css(). | |
223dbc38 TH |
5048 | */ |
5049 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 5050 | { |
223dbc38 TH |
5051 | struct cgroup_subsys_state *css = |
5052 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
d3daf28d | 5053 | |
f20104de | 5054 | mutex_lock(&cgroup_mutex); |
09a503ea | 5055 | |
aa226ff4 TH |
5056 | do { |
5057 | offline_css(css); | |
5058 | css_put(css); | |
5059 | /* @css can't go away while we're holding cgroup_mutex */ | |
5060 | css = css->parent; | |
5061 | } while (css && atomic_dec_and_test(&css->online_cnt)); | |
5062 | ||
5063 | mutex_unlock(&cgroup_mutex); | |
d3daf28d TH |
5064 | } |
5065 | ||
223dbc38 TH |
5066 | /* css kill confirmation processing requires process context, bounce */ |
5067 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
5068 | { |
5069 | struct cgroup_subsys_state *css = | |
5070 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
5071 | ||
aa226ff4 TH |
5072 | if (atomic_dec_and_test(&css->online_cnt)) { |
5073 | INIT_WORK(&css->destroy_work, css_killed_work_fn); | |
5074 | queue_work(cgroup_destroy_wq, &css->destroy_work); | |
5075 | } | |
d3daf28d TH |
5076 | } |
5077 | ||
f392e51c TH |
5078 | /** |
5079 | * kill_css - destroy a css | |
5080 | * @css: css to destroy | |
5081 | * | |
5082 | * This function initiates destruction of @css by removing cgroup interface | |
5083 | * files and putting its base reference. ->css_offline() will be invoked | |
ec903c0c TH |
5084 | * asynchronously once css_tryget_online() is guaranteed to fail and when |
5085 | * the reference count reaches zero, @css will be released. | |
f392e51c TH |
5086 | */ |
5087 | static void kill_css(struct cgroup_subsys_state *css) | |
edae0c33 | 5088 | { |
01f6474c | 5089 | lockdep_assert_held(&cgroup_mutex); |
94419627 | 5090 | |
2bd59d48 TH |
5091 | /* |
5092 | * This must happen before css is disassociated with its cgroup. | |
5093 | * See seq_css() for details. | |
5094 | */ | |
4df8dc90 | 5095 | css_clear_dir(css, NULL); |
3c14f8b4 | 5096 | |
edae0c33 TH |
5097 | /* |
5098 | * Killing would put the base ref, but we need to keep it alive | |
5099 | * until after ->css_offline(). | |
5100 | */ | |
5101 | css_get(css); | |
5102 | ||
5103 | /* | |
5104 | * cgroup core guarantees that, by the time ->css_offline() is | |
5105 | * invoked, no new css reference will be given out via | |
ec903c0c | 5106 | * css_tryget_online(). We can't simply call percpu_ref_kill() and |
edae0c33 TH |
5107 | * proceed to offlining css's because percpu_ref_kill() doesn't |
5108 | * guarantee that the ref is seen as killed on all CPUs on return. | |
5109 | * | |
5110 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
5111 | * css is confirmed to be seen as killed on all CPUs. | |
5112 | */ | |
5113 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
5114 | } |
5115 | ||
5116 | /** | |
5117 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
5118 | * @cgrp: cgroup to be destroyed | |
5119 | * | |
5120 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
5121 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
ec903c0c TH |
5122 | * guarantee that css_tryget_online() won't succeed by the time |
5123 | * ->css_offline() is invoked. To satisfy all the requirements, | |
5124 | * destruction is implemented in the following two steps. | |
d3daf28d TH |
5125 | * |
5126 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
5127 | * userland visible parts and start killing the percpu refcnts of | |
5128 | * css's. Set up so that the next stage will be kicked off once all | |
5129 | * the percpu refcnts are confirmed to be killed. | |
5130 | * | |
5131 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
5132 | * rest of destruction. Once all cgroup references are gone, the | |
5133 | * cgroup is RCU-freed. | |
5134 | * | |
5135 | * This function implements s1. After this step, @cgrp is gone as far as | |
5136 | * the userland is concerned and a new cgroup with the same name may be | |
5137 | * created. As cgroup doesn't care about the names internally, this | |
5138 | * doesn't cause any problem. | |
5139 | */ | |
42809dd4 TH |
5140 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
5141 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 5142 | { |
2bd59d48 | 5143 | struct cgroup_subsys_state *css; |
1c6727af | 5144 | int ssid; |
ddbcc7e8 | 5145 | |
42809dd4 TH |
5146 | lockdep_assert_held(&cgroup_mutex); |
5147 | ||
91486f61 TH |
5148 | /* |
5149 | * Only migration can raise populated from zero and we're already | |
5150 | * holding cgroup_mutex. | |
5151 | */ | |
5152 | if (cgroup_is_populated(cgrp)) | |
ddbcc7e8 | 5153 | return -EBUSY; |
a043e3b2 | 5154 | |
bb78a92f | 5155 | /* |
d5c419b6 TH |
5156 | * Make sure there's no live children. We can't test emptiness of |
5157 | * ->self.children as dead children linger on it while being | |
5158 | * drained; otherwise, "rmdir parent/child parent" may fail. | |
bb78a92f | 5159 | */ |
f3d46500 | 5160 | if (css_has_online_children(&cgrp->self)) |
bb78a92f HD |
5161 | return -EBUSY; |
5162 | ||
455050d2 TH |
5163 | /* |
5164 | * Mark @cgrp dead. This prevents further task migration and child | |
de3f0341 | 5165 | * creation by disabling cgroup_lock_live_group(). |
455050d2 | 5166 | */ |
184faf32 | 5167 | cgrp->self.flags &= ~CSS_ONLINE; |
ddbcc7e8 | 5168 | |
249f3468 | 5169 | /* initiate massacre of all css's */ |
1c6727af TH |
5170 | for_each_css(css, ssid, cgrp) |
5171 | kill_css(css); | |
455050d2 | 5172 | |
455050d2 | 5173 | /* |
01f6474c TH |
5174 | * Remove @cgrp directory along with the base files. @cgrp has an |
5175 | * extra ref on its kn. | |
f20104de | 5176 | */ |
01f6474c | 5177 | kernfs_remove(cgrp->kn); |
f20104de | 5178 | |
d51f39b0 | 5179 | check_for_release(cgroup_parent(cgrp)); |
2bd59d48 | 5180 | |
249f3468 | 5181 | /* put the base reference */ |
9d755d33 | 5182 | percpu_ref_kill(&cgrp->self.refcnt); |
455050d2 | 5183 | |
ea15f8cc TH |
5184 | return 0; |
5185 | }; | |
5186 | ||
2bd59d48 | 5187 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 5188 | { |
a9746d8d | 5189 | struct cgroup *cgrp; |
2bd59d48 | 5190 | int ret = 0; |
42809dd4 | 5191 | |
a9746d8d TH |
5192 | cgrp = cgroup_kn_lock_live(kn); |
5193 | if (!cgrp) | |
5194 | return 0; | |
42809dd4 | 5195 | |
a9746d8d | 5196 | ret = cgroup_destroy_locked(cgrp); |
2bb566cb | 5197 | |
a9746d8d | 5198 | cgroup_kn_unlock(kn); |
42809dd4 | 5199 | return ret; |
8e3f6541 TH |
5200 | } |
5201 | ||
2bd59d48 TH |
5202 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
5203 | .remount_fs = cgroup_remount, | |
5204 | .show_options = cgroup_show_options, | |
5205 | .mkdir = cgroup_mkdir, | |
5206 | .rmdir = cgroup_rmdir, | |
5207 | .rename = cgroup_rename, | |
5208 | }; | |
5209 | ||
15a4c835 | 5210 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) |
ddbcc7e8 | 5211 | { |
ddbcc7e8 | 5212 | struct cgroup_subsys_state *css; |
cfe36bde | 5213 | |
a5ae9899 | 5214 | pr_debug("Initializing cgroup subsys %s\n", ss->name); |
ddbcc7e8 | 5215 | |
648bb56d TH |
5216 | mutex_lock(&cgroup_mutex); |
5217 | ||
15a4c835 | 5218 | idr_init(&ss->css_idr); |
0adb0704 | 5219 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 5220 | |
3dd06ffa TH |
5221 | /* Create the root cgroup state for this subsystem */ |
5222 | ss->root = &cgrp_dfl_root; | |
5223 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); | |
ddbcc7e8 PM |
5224 | /* We don't handle early failures gracefully */ |
5225 | BUG_ON(IS_ERR(css)); | |
ddfcadab | 5226 | init_and_link_css(css, ss, &cgrp_dfl_root.cgrp); |
3b514d24 TH |
5227 | |
5228 | /* | |
5229 | * Root csses are never destroyed and we can't initialize | |
5230 | * percpu_ref during early init. Disable refcnting. | |
5231 | */ | |
5232 | css->flags |= CSS_NO_REF; | |
5233 | ||
15a4c835 | 5234 | if (early) { |
9395a450 | 5235 | /* allocation can't be done safely during early init */ |
15a4c835 TH |
5236 | css->id = 1; |
5237 | } else { | |
5238 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL); | |
5239 | BUG_ON(css->id < 0); | |
5240 | } | |
ddbcc7e8 | 5241 | |
e8d55fde | 5242 | /* Update the init_css_set to contain a subsys |
817929ec | 5243 | * pointer to this state - since the subsystem is |
e8d55fde | 5244 | * newly registered, all tasks and hence the |
3dd06ffa | 5245 | * init_css_set is in the subsystem's root cgroup. */ |
aec25020 | 5246 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 | 5247 | |
cb4a3167 AS |
5248 | have_fork_callback |= (bool)ss->fork << ss->id; |
5249 | have_exit_callback |= (bool)ss->exit << ss->id; | |
afcf6c8b | 5250 | have_free_callback |= (bool)ss->free << ss->id; |
7e47682e | 5251 | have_canfork_callback |= (bool)ss->can_fork << ss->id; |
ddbcc7e8 | 5252 | |
e8d55fde LZ |
5253 | /* At system boot, before all subsystems have been |
5254 | * registered, no tasks have been forked, so we don't | |
5255 | * need to invoke fork callbacks here. */ | |
5256 | BUG_ON(!list_empty(&init_task.tasks)); | |
5257 | ||
ae7f164a | 5258 | BUG_ON(online_css(css)); |
a8638030 | 5259 | |
cf5d5941 BB |
5260 | mutex_unlock(&cgroup_mutex); |
5261 | } | |
cf5d5941 | 5262 | |
ddbcc7e8 | 5263 | /** |
a043e3b2 LZ |
5264 | * cgroup_init_early - cgroup initialization at system boot |
5265 | * | |
5266 | * Initialize cgroups at system boot, and initialize any | |
5267 | * subsystems that request early init. | |
ddbcc7e8 PM |
5268 | */ |
5269 | int __init cgroup_init_early(void) | |
5270 | { | |
7b9a6ba5 | 5271 | static struct cgroup_sb_opts __initdata opts; |
30159ec7 | 5272 | struct cgroup_subsys *ss; |
ddbcc7e8 | 5273 | int i; |
30159ec7 | 5274 | |
3dd06ffa | 5275 | init_cgroup_root(&cgrp_dfl_root, &opts); |
3b514d24 TH |
5276 | cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF; |
5277 | ||
a4ea1cc9 | 5278 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 5279 | |
3ed80a62 | 5280 | for_each_subsys(ss, i) { |
aec25020 | 5281 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
63253ad8 | 5282 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n", |
073219e9 | 5283 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, |
aec25020 | 5284 | ss->id, ss->name); |
073219e9 TH |
5285 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
5286 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
5287 | ||
aec25020 | 5288 | ss->id = i; |
073219e9 | 5289 | ss->name = cgroup_subsys_name[i]; |
3e1d2eed TH |
5290 | if (!ss->legacy_name) |
5291 | ss->legacy_name = cgroup_subsys_name[i]; | |
ddbcc7e8 PM |
5292 | |
5293 | if (ss->early_init) | |
15a4c835 | 5294 | cgroup_init_subsys(ss, true); |
ddbcc7e8 PM |
5295 | } |
5296 | return 0; | |
5297 | } | |
5298 | ||
6e5c8307 | 5299 | static u16 cgroup_disable_mask __initdata; |
a3e72739 | 5300 | |
ddbcc7e8 | 5301 | /** |
a043e3b2 LZ |
5302 | * cgroup_init - cgroup initialization |
5303 | * | |
5304 | * Register cgroup filesystem and /proc file, and initialize | |
5305 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
5306 | */ |
5307 | int __init cgroup_init(void) | |
5308 | { | |
30159ec7 | 5309 | struct cgroup_subsys *ss; |
035f4f51 | 5310 | int ssid; |
ddbcc7e8 | 5311 | |
6e5c8307 | 5312 | BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16); |
1ed13287 | 5313 | BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); |
a14c6874 TH |
5314 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); |
5315 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); | |
ddbcc7e8 | 5316 | |
54e7b4eb | 5317 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 5318 | |
2378d8b8 TH |
5319 | /* |
5320 | * Add init_css_set to the hash table so that dfl_root can link to | |
5321 | * it during init. | |
5322 | */ | |
5323 | hash_add(css_set_table, &init_css_set.hlist, | |
5324 | css_set_hash(init_css_set.subsys)); | |
82fe9b0d | 5325 | |
3dd06ffa | 5326 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
4e96ee8e | 5327 | |
54e7b4eb TH |
5328 | mutex_unlock(&cgroup_mutex); |
5329 | ||
172a2c06 | 5330 | for_each_subsys(ss, ssid) { |
15a4c835 TH |
5331 | if (ss->early_init) { |
5332 | struct cgroup_subsys_state *css = | |
5333 | init_css_set.subsys[ss->id]; | |
5334 | ||
5335 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, | |
5336 | GFP_KERNEL); | |
5337 | BUG_ON(css->id < 0); | |
5338 | } else { | |
5339 | cgroup_init_subsys(ss, false); | |
5340 | } | |
172a2c06 | 5341 | |
2d8f243a TH |
5342 | list_add_tail(&init_css_set.e_cset_node[ssid], |
5343 | &cgrp_dfl_root.cgrp.e_csets[ssid]); | |
172a2c06 TH |
5344 | |
5345 | /* | |
c731ae1d LZ |
5346 | * Setting dfl_root subsys_mask needs to consider the |
5347 | * disabled flag and cftype registration needs kmalloc, | |
5348 | * both of which aren't available during early_init. | |
172a2c06 | 5349 | */ |
a3e72739 TH |
5350 | if (cgroup_disable_mask & (1 << ssid)) { |
5351 | static_branch_disable(cgroup_subsys_enabled_key[ssid]); | |
5352 | printk(KERN_INFO "Disabling %s control group subsystem\n", | |
5353 | ss->name); | |
a8ddc821 | 5354 | continue; |
a3e72739 | 5355 | } |
a8ddc821 | 5356 | |
223ffb29 JW |
5357 | if (cgroup_ssid_no_v1(ssid)) |
5358 | printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n", | |
5359 | ss->name); | |
5360 | ||
a8ddc821 TH |
5361 | cgrp_dfl_root.subsys_mask |= 1 << ss->id; |
5362 | ||
5de4fa13 | 5363 | if (!ss->dfl_cftypes) |
a7165264 | 5364 | cgrp_dfl_inhibit_ss_mask |= 1 << ss->id; |
5de4fa13 | 5365 | |
a8ddc821 TH |
5366 | if (ss->dfl_cftypes == ss->legacy_cftypes) { |
5367 | WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes)); | |
5368 | } else { | |
5369 | WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes)); | |
5370 | WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes)); | |
c731ae1d | 5371 | } |
295458e6 VD |
5372 | |
5373 | if (ss->bind) | |
5374 | ss->bind(init_css_set.subsys[ssid]); | |
676db4af GK |
5375 | } |
5376 | ||
2378d8b8 TH |
5377 | /* init_css_set.subsys[] has been updated, re-hash */ |
5378 | hash_del(&init_css_set.hlist); | |
5379 | hash_add(css_set_table, &init_css_set.hlist, | |
5380 | css_set_hash(init_css_set.subsys)); | |
5381 | ||
035f4f51 TH |
5382 | WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup")); |
5383 | WARN_ON(register_filesystem(&cgroup_fs_type)); | |
67e9c74b | 5384 | WARN_ON(register_filesystem(&cgroup2_fs_type)); |
035f4f51 | 5385 | WARN_ON(!proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations)); |
ddbcc7e8 | 5386 | |
2bd59d48 | 5387 | return 0; |
ddbcc7e8 | 5388 | } |
b4f48b63 | 5389 | |
e5fca243 TH |
5390 | static int __init cgroup_wq_init(void) |
5391 | { | |
5392 | /* | |
5393 | * There isn't much point in executing destruction path in | |
5394 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 5395 | * Use 1 for @max_active. |
e5fca243 TH |
5396 | * |
5397 | * We would prefer to do this in cgroup_init() above, but that | |
5398 | * is called before init_workqueues(): so leave this until after. | |
5399 | */ | |
1a11533f | 5400 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 5401 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
5402 | |
5403 | /* | |
5404 | * Used to destroy pidlists and separate to serve as flush domain. | |
5405 | * Cap @max_active to 1 too. | |
5406 | */ | |
5407 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
5408 | 0, 1); | |
5409 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
5410 | ||
e5fca243 TH |
5411 | return 0; |
5412 | } | |
5413 | core_initcall(cgroup_wq_init); | |
5414 | ||
a424316c PM |
5415 | /* |
5416 | * proc_cgroup_show() | |
5417 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
5418 | * - Used for /proc/<pid>/cgroup. | |
a424316c | 5419 | */ |
006f4ac4 ZL |
5420 | int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, |
5421 | struct pid *pid, struct task_struct *tsk) | |
a424316c | 5422 | { |
e61734c5 | 5423 | char *buf, *path; |
a424316c | 5424 | int retval; |
3dd06ffa | 5425 | struct cgroup_root *root; |
a424316c PM |
5426 | |
5427 | retval = -ENOMEM; | |
e61734c5 | 5428 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
5429 | if (!buf) |
5430 | goto out; | |
5431 | ||
a424316c | 5432 | mutex_lock(&cgroup_mutex); |
f0d9a5f1 | 5433 | spin_lock_bh(&css_set_lock); |
a424316c | 5434 | |
985ed670 | 5435 | for_each_root(root) { |
a424316c | 5436 | struct cgroup_subsys *ss; |
bd89aabc | 5437 | struct cgroup *cgrp; |
b85d2040 | 5438 | int ssid, count = 0; |
a424316c | 5439 | |
a7165264 | 5440 | if (root == &cgrp_dfl_root && !cgrp_dfl_visible) |
985ed670 TH |
5441 | continue; |
5442 | ||
2c6ab6d2 | 5443 | seq_printf(m, "%d:", root->hierarchy_id); |
d98817d4 TH |
5444 | if (root != &cgrp_dfl_root) |
5445 | for_each_subsys(ss, ssid) | |
5446 | if (root->subsys_mask & (1 << ssid)) | |
5447 | seq_printf(m, "%s%s", count++ ? "," : "", | |
3e1d2eed | 5448 | ss->legacy_name); |
c6d57f33 PM |
5449 | if (strlen(root->name)) |
5450 | seq_printf(m, "%sname=%s", count ? "," : "", | |
5451 | root->name); | |
a424316c | 5452 | seq_putc(m, ':'); |
2e91fa7f | 5453 | |
7717f7ba | 5454 | cgrp = task_cgroup_from_root(tsk, root); |
2e91fa7f TH |
5455 | |
5456 | /* | |
5457 | * On traditional hierarchies, all zombie tasks show up as | |
5458 | * belonging to the root cgroup. On the default hierarchy, | |
5459 | * while a zombie doesn't show up in "cgroup.procs" and | |
5460 | * thus can't be migrated, its /proc/PID/cgroup keeps | |
5461 | * reporting the cgroup it belonged to before exiting. If | |
5462 | * the cgroup is removed before the zombie is reaped, | |
5463 | * " (deleted)" is appended to the cgroup path. | |
5464 | */ | |
5465 | if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) { | |
5466 | path = cgroup_path(cgrp, buf, PATH_MAX); | |
5467 | if (!path) { | |
5468 | retval = -ENAMETOOLONG; | |
5469 | goto out_unlock; | |
5470 | } | |
5471 | } else { | |
5472 | path = "/"; | |
e61734c5 | 5473 | } |
2e91fa7f | 5474 | |
e61734c5 | 5475 | seq_puts(m, path); |
2e91fa7f TH |
5476 | |
5477 | if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp)) | |
5478 | seq_puts(m, " (deleted)\n"); | |
5479 | else | |
5480 | seq_putc(m, '\n'); | |
a424316c PM |
5481 | } |
5482 | ||
006f4ac4 | 5483 | retval = 0; |
a424316c | 5484 | out_unlock: |
f0d9a5f1 | 5485 | spin_unlock_bh(&css_set_lock); |
a424316c | 5486 | mutex_unlock(&cgroup_mutex); |
a424316c PM |
5487 | kfree(buf); |
5488 | out: | |
5489 | return retval; | |
5490 | } | |
5491 | ||
a424316c PM |
5492 | /* Display information about each subsystem and each hierarchy */ |
5493 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
5494 | { | |
30159ec7 | 5495 | struct cgroup_subsys *ss; |
a424316c | 5496 | int i; |
a424316c | 5497 | |
8bab8dde | 5498 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
5499 | /* |
5500 | * ideally we don't want subsystems moving around while we do this. | |
5501 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
5502 | * subsys/hierarchy state. | |
5503 | */ | |
a424316c | 5504 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
5505 | |
5506 | for_each_subsys(ss, i) | |
2c6ab6d2 | 5507 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
3e1d2eed | 5508 | ss->legacy_name, ss->root->hierarchy_id, |
fc5ed1e9 TH |
5509 | atomic_read(&ss->root->nr_cgrps), |
5510 | cgroup_ssid_enabled(i)); | |
30159ec7 | 5511 | |
a424316c PM |
5512 | mutex_unlock(&cgroup_mutex); |
5513 | return 0; | |
5514 | } | |
5515 | ||
5516 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
5517 | { | |
9dce07f1 | 5518 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
5519 | } |
5520 | ||
828c0950 | 5521 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
5522 | .open = cgroupstats_open, |
5523 | .read = seq_read, | |
5524 | .llseek = seq_lseek, | |
5525 | .release = single_release, | |
5526 | }; | |
5527 | ||
b4f48b63 | 5528 | /** |
eaf797ab | 5529 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 5530 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 5531 | * |
eaf797ab TH |
5532 | * A task is associated with the init_css_set until cgroup_post_fork() |
5533 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
5534 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
5535 | */ |
5536 | void cgroup_fork(struct task_struct *child) | |
5537 | { | |
eaf797ab | 5538 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 5539 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
5540 | } |
5541 | ||
7e47682e AS |
5542 | /** |
5543 | * cgroup_can_fork - called on a new task before the process is exposed | |
5544 | * @child: the task in question. | |
5545 | * | |
5546 | * This calls the subsystem can_fork() callbacks. If the can_fork() callback | |
5547 | * returns an error, the fork aborts with that error code. This allows for | |
5548 | * a cgroup subsystem to conditionally allow or deny new forks. | |
5549 | */ | |
b53202e6 | 5550 | int cgroup_can_fork(struct task_struct *child) |
7e47682e AS |
5551 | { |
5552 | struct cgroup_subsys *ss; | |
5553 | int i, j, ret; | |
5554 | ||
b4e0eeaf | 5555 | do_each_subsys_mask(ss, i, have_canfork_callback) { |
b53202e6 | 5556 | ret = ss->can_fork(child); |
7e47682e AS |
5557 | if (ret) |
5558 | goto out_revert; | |
b4e0eeaf | 5559 | } while_each_subsys_mask(); |
7e47682e AS |
5560 | |
5561 | return 0; | |
5562 | ||
5563 | out_revert: | |
5564 | for_each_subsys(ss, j) { | |
5565 | if (j >= i) | |
5566 | break; | |
5567 | if (ss->cancel_fork) | |
b53202e6 | 5568 | ss->cancel_fork(child); |
7e47682e AS |
5569 | } |
5570 | ||
5571 | return ret; | |
5572 | } | |
5573 | ||
5574 | /** | |
5575 | * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() | |
5576 | * @child: the task in question | |
5577 | * | |
5578 | * This calls the cancel_fork() callbacks if a fork failed *after* | |
5579 | * cgroup_can_fork() succeded. | |
5580 | */ | |
b53202e6 | 5581 | void cgroup_cancel_fork(struct task_struct *child) |
7e47682e AS |
5582 | { |
5583 | struct cgroup_subsys *ss; | |
5584 | int i; | |
5585 | ||
5586 | for_each_subsys(ss, i) | |
5587 | if (ss->cancel_fork) | |
b53202e6 | 5588 | ss->cancel_fork(child); |
7e47682e AS |
5589 | } |
5590 | ||
817929ec | 5591 | /** |
a043e3b2 LZ |
5592 | * cgroup_post_fork - called on a new task after adding it to the task list |
5593 | * @child: the task in question | |
5594 | * | |
5edee61e TH |
5595 | * Adds the task to the list running through its css_set if necessary and |
5596 | * call the subsystem fork() callbacks. Has to be after the task is | |
5597 | * visible on the task list in case we race with the first call to | |
0942eeee | 5598 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 5599 | * list. |
a043e3b2 | 5600 | */ |
b53202e6 | 5601 | void cgroup_post_fork(struct task_struct *child) |
817929ec | 5602 | { |
30159ec7 | 5603 | struct cgroup_subsys *ss; |
5edee61e TH |
5604 | int i; |
5605 | ||
3ce3230a | 5606 | /* |
251f8c03 | 5607 | * This may race against cgroup_enable_task_cg_lists(). As that |
eaf797ab TH |
5608 | * function sets use_task_css_set_links before grabbing |
5609 | * tasklist_lock and we just went through tasklist_lock to add | |
5610 | * @child, it's guaranteed that either we see the set | |
5611 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
5612 | * @child during its iteration. | |
5613 | * | |
5614 | * If we won the race, @child is associated with %current's | |
f0d9a5f1 | 5615 | * css_set. Grabbing css_set_lock guarantees both that the |
eaf797ab TH |
5616 | * association is stable, and, on completion of the parent's |
5617 | * migration, @child is visible in the source of migration or | |
5618 | * already in the destination cgroup. This guarantee is necessary | |
5619 | * when implementing operations which need to migrate all tasks of | |
5620 | * a cgroup to another. | |
5621 | * | |
251f8c03 | 5622 | * Note that if we lose to cgroup_enable_task_cg_lists(), @child |
eaf797ab TH |
5623 | * will remain in init_css_set. This is safe because all tasks are |
5624 | * in the init_css_set before cg_links is enabled and there's no | |
5625 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 5626 | */ |
817929ec | 5627 | if (use_task_css_set_links) { |
eaf797ab TH |
5628 | struct css_set *cset; |
5629 | ||
f0d9a5f1 | 5630 | spin_lock_bh(&css_set_lock); |
0e1d768f | 5631 | cset = task_css_set(current); |
eaf797ab | 5632 | if (list_empty(&child->cg_list)) { |
eaf797ab | 5633 | get_css_set(cset); |
f6d7d049 | 5634 | css_set_move_task(child, NULL, cset, false); |
eaf797ab | 5635 | } |
f0d9a5f1 | 5636 | spin_unlock_bh(&css_set_lock); |
817929ec | 5637 | } |
5edee61e TH |
5638 | |
5639 | /* | |
5640 | * Call ss->fork(). This must happen after @child is linked on | |
5641 | * css_set; otherwise, @child might change state between ->fork() | |
5642 | * and addition to css_set. | |
5643 | */ | |
b4e0eeaf | 5644 | do_each_subsys_mask(ss, i, have_fork_callback) { |
b53202e6 | 5645 | ss->fork(child); |
b4e0eeaf | 5646 | } while_each_subsys_mask(); |
817929ec | 5647 | } |
5edee61e | 5648 | |
b4f48b63 PM |
5649 | /** |
5650 | * cgroup_exit - detach cgroup from exiting task | |
5651 | * @tsk: pointer to task_struct of exiting process | |
5652 | * | |
5653 | * Description: Detach cgroup from @tsk and release it. | |
5654 | * | |
5655 | * Note that cgroups marked notify_on_release force every task in | |
5656 | * them to take the global cgroup_mutex mutex when exiting. | |
5657 | * This could impact scaling on very large systems. Be reluctant to | |
5658 | * use notify_on_release cgroups where very high task exit scaling | |
5659 | * is required on large systems. | |
5660 | * | |
0e1d768f TH |
5661 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
5662 | * call cgroup_exit() while the task is still competent to handle | |
5663 | * notify_on_release(), then leave the task attached to the root cgroup in | |
5664 | * each hierarchy for the remainder of its exit. No need to bother with | |
5665 | * init_css_set refcnting. init_css_set never goes away and we can't race | |
e8604cb4 | 5666 | * with migration path - PF_EXITING is visible to migration path. |
b4f48b63 | 5667 | */ |
1ec41830 | 5668 | void cgroup_exit(struct task_struct *tsk) |
b4f48b63 | 5669 | { |
30159ec7 | 5670 | struct cgroup_subsys *ss; |
5abb8855 | 5671 | struct css_set *cset; |
d41d5a01 | 5672 | int i; |
817929ec PM |
5673 | |
5674 | /* | |
0e1d768f | 5675 | * Unlink from @tsk from its css_set. As migration path can't race |
0de0942d | 5676 | * with us, we can check css_set and cg_list without synchronization. |
817929ec | 5677 | */ |
0de0942d TH |
5678 | cset = task_css_set(tsk); |
5679 | ||
817929ec | 5680 | if (!list_empty(&tsk->cg_list)) { |
f0d9a5f1 | 5681 | spin_lock_bh(&css_set_lock); |
f6d7d049 | 5682 | css_set_move_task(tsk, cset, NULL, false); |
f0d9a5f1 | 5683 | spin_unlock_bh(&css_set_lock); |
2e91fa7f TH |
5684 | } else { |
5685 | get_css_set(cset); | |
817929ec PM |
5686 | } |
5687 | ||
cb4a3167 | 5688 | /* see cgroup_post_fork() for details */ |
b4e0eeaf | 5689 | do_each_subsys_mask(ss, i, have_exit_callback) { |
2e91fa7f | 5690 | ss->exit(tsk); |
b4e0eeaf | 5691 | } while_each_subsys_mask(); |
2e91fa7f | 5692 | } |
30159ec7 | 5693 | |
2e91fa7f TH |
5694 | void cgroup_free(struct task_struct *task) |
5695 | { | |
5696 | struct css_set *cset = task_css_set(task); | |
afcf6c8b TH |
5697 | struct cgroup_subsys *ss; |
5698 | int ssid; | |
5699 | ||
b4e0eeaf | 5700 | do_each_subsys_mask(ss, ssid, have_free_callback) { |
afcf6c8b | 5701 | ss->free(task); |
b4e0eeaf | 5702 | } while_each_subsys_mask(); |
d41d5a01 | 5703 | |
2e91fa7f | 5704 | put_css_set(cset); |
b4f48b63 | 5705 | } |
697f4161 | 5706 | |
bd89aabc | 5707 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 5708 | { |
27bd4dbb | 5709 | if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) && |
971ff493 ZL |
5710 | !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
5711 | schedule_work(&cgrp->release_agent_work); | |
81a6a5cd PM |
5712 | } |
5713 | ||
81a6a5cd PM |
5714 | /* |
5715 | * Notify userspace when a cgroup is released, by running the | |
5716 | * configured release agent with the name of the cgroup (path | |
5717 | * relative to the root of cgroup file system) as the argument. | |
5718 | * | |
5719 | * Most likely, this user command will try to rmdir this cgroup. | |
5720 | * | |
5721 | * This races with the possibility that some other task will be | |
5722 | * attached to this cgroup before it is removed, or that some other | |
5723 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5724 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5725 | * unused, and this cgroup will be reprieved from its death sentence, | |
5726 | * to continue to serve a useful existence. Next time it's released, | |
5727 | * we will get notified again, if it still has 'notify_on_release' set. | |
5728 | * | |
5729 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5730 | * means only wait until the task is successfully execve()'d. The | |
5731 | * separate release agent task is forked by call_usermodehelper(), | |
5732 | * then control in this thread returns here, without waiting for the | |
5733 | * release agent task. We don't bother to wait because the caller of | |
5734 | * this routine has no use for the exit status of the release agent | |
5735 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5736 | */ |
81a6a5cd PM |
5737 | static void cgroup_release_agent(struct work_struct *work) |
5738 | { | |
971ff493 ZL |
5739 | struct cgroup *cgrp = |
5740 | container_of(work, struct cgroup, release_agent_work); | |
5741 | char *pathbuf = NULL, *agentbuf = NULL, *path; | |
5742 | char *argv[3], *envp[3]; | |
5743 | ||
81a6a5cd | 5744 | mutex_lock(&cgroup_mutex); |
971ff493 ZL |
5745 | |
5746 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); | |
5747 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5748 | if (!pathbuf || !agentbuf) | |
5749 | goto out; | |
5750 | ||
5751 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); | |
5752 | if (!path) | |
5753 | goto out; | |
5754 | ||
5755 | argv[0] = agentbuf; | |
5756 | argv[1] = path; | |
5757 | argv[2] = NULL; | |
5758 | ||
5759 | /* minimal command environment */ | |
5760 | envp[0] = "HOME=/"; | |
5761 | envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5762 | envp[2] = NULL; | |
5763 | ||
81a6a5cd | 5764 | mutex_unlock(&cgroup_mutex); |
971ff493 | 5765 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
3e2cd91a | 5766 | goto out_free; |
971ff493 | 5767 | out: |
81a6a5cd | 5768 | mutex_unlock(&cgroup_mutex); |
3e2cd91a | 5769 | out_free: |
971ff493 ZL |
5770 | kfree(agentbuf); |
5771 | kfree(pathbuf); | |
81a6a5cd | 5772 | } |
8bab8dde PM |
5773 | |
5774 | static int __init cgroup_disable(char *str) | |
5775 | { | |
30159ec7 | 5776 | struct cgroup_subsys *ss; |
8bab8dde | 5777 | char *token; |
30159ec7 | 5778 | int i; |
8bab8dde PM |
5779 | |
5780 | while ((token = strsep(&str, ",")) != NULL) { | |
5781 | if (!*token) | |
5782 | continue; | |
be45c900 | 5783 | |
3ed80a62 | 5784 | for_each_subsys(ss, i) { |
3e1d2eed TH |
5785 | if (strcmp(token, ss->name) && |
5786 | strcmp(token, ss->legacy_name)) | |
5787 | continue; | |
a3e72739 | 5788 | cgroup_disable_mask |= 1 << i; |
8bab8dde PM |
5789 | } |
5790 | } | |
5791 | return 1; | |
5792 | } | |
5793 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 5794 | |
223ffb29 JW |
5795 | static int __init cgroup_no_v1(char *str) |
5796 | { | |
5797 | struct cgroup_subsys *ss; | |
5798 | char *token; | |
5799 | int i; | |
5800 | ||
5801 | while ((token = strsep(&str, ",")) != NULL) { | |
5802 | if (!*token) | |
5803 | continue; | |
5804 | ||
5805 | if (!strcmp(token, "all")) { | |
6e5c8307 | 5806 | cgroup_no_v1_mask = U16_MAX; |
223ffb29 JW |
5807 | break; |
5808 | } | |
5809 | ||
5810 | for_each_subsys(ss, i) { | |
5811 | if (strcmp(token, ss->name) && | |
5812 | strcmp(token, ss->legacy_name)) | |
5813 | continue; | |
5814 | ||
5815 | cgroup_no_v1_mask |= 1 << i; | |
5816 | } | |
5817 | } | |
5818 | return 1; | |
5819 | } | |
5820 | __setup("cgroup_no_v1=", cgroup_no_v1); | |
5821 | ||
b77d7b60 | 5822 | /** |
ec903c0c | 5823 | * css_tryget_online_from_dir - get corresponding css from a cgroup dentry |
35cf0836 TH |
5824 | * @dentry: directory dentry of interest |
5825 | * @ss: subsystem of interest | |
b77d7b60 | 5826 | * |
5a17f543 TH |
5827 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
5828 | * to get the corresponding css and return it. If such css doesn't exist | |
5829 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 5830 | */ |
ec903c0c TH |
5831 | struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
5832 | struct cgroup_subsys *ss) | |
e5d1367f | 5833 | { |
2bd59d48 | 5834 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
f17fc25f | 5835 | struct file_system_type *s_type = dentry->d_sb->s_type; |
2bd59d48 | 5836 | struct cgroup_subsys_state *css = NULL; |
e5d1367f | 5837 | struct cgroup *cgrp; |
e5d1367f | 5838 | |
35cf0836 | 5839 | /* is @dentry a cgroup dir? */ |
f17fc25f TH |
5840 | if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) || |
5841 | !kn || kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
5842 | return ERR_PTR(-EBADF); |
5843 | ||
5a17f543 TH |
5844 | rcu_read_lock(); |
5845 | ||
2bd59d48 TH |
5846 | /* |
5847 | * This path doesn't originate from kernfs and @kn could already | |
5848 | * have been or be removed at any point. @kn->priv is RCU | |
a4189487 | 5849 | * protected for this access. See css_release_work_fn() for details. |
2bd59d48 TH |
5850 | */ |
5851 | cgrp = rcu_dereference(kn->priv); | |
5852 | if (cgrp) | |
5853 | css = cgroup_css(cgrp, ss); | |
5a17f543 | 5854 | |
ec903c0c | 5855 | if (!css || !css_tryget_online(css)) |
5a17f543 TH |
5856 | css = ERR_PTR(-ENOENT); |
5857 | ||
5858 | rcu_read_unlock(); | |
5859 | return css; | |
e5d1367f | 5860 | } |
e5d1367f | 5861 | |
1cb650b9 LZ |
5862 | /** |
5863 | * css_from_id - lookup css by id | |
5864 | * @id: the cgroup id | |
5865 | * @ss: cgroup subsys to be looked into | |
5866 | * | |
5867 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
5868 | * Should be called under rcu_read_lock(). | |
5869 | */ | |
5870 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
5871 | { | |
6fa4918d | 5872 | WARN_ON_ONCE(!rcu_read_lock_held()); |
adbe427b | 5873 | return id > 0 ? idr_find(&ss->css_idr, id) : NULL; |
e5d1367f SE |
5874 | } |
5875 | ||
16af4396 TH |
5876 | /** |
5877 | * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path | |
5878 | * @path: path on the default hierarchy | |
5879 | * | |
5880 | * Find the cgroup at @path on the default hierarchy, increment its | |
5881 | * reference count and return it. Returns pointer to the found cgroup on | |
5882 | * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR) | |
5883 | * if @path points to a non-directory. | |
5884 | */ | |
5885 | struct cgroup *cgroup_get_from_path(const char *path) | |
5886 | { | |
5887 | struct kernfs_node *kn; | |
5888 | struct cgroup *cgrp; | |
5889 | ||
5890 | mutex_lock(&cgroup_mutex); | |
5891 | ||
5892 | kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path); | |
5893 | if (kn) { | |
5894 | if (kernfs_type(kn) == KERNFS_DIR) { | |
5895 | cgrp = kn->priv; | |
5896 | cgroup_get(cgrp); | |
5897 | } else { | |
5898 | cgrp = ERR_PTR(-ENOTDIR); | |
5899 | } | |
5900 | kernfs_put(kn); | |
5901 | } else { | |
5902 | cgrp = ERR_PTR(-ENOENT); | |
5903 | } | |
5904 | ||
5905 | mutex_unlock(&cgroup_mutex); | |
5906 | return cgrp; | |
5907 | } | |
5908 | EXPORT_SYMBOL_GPL(cgroup_get_from_path); | |
5909 | ||
bd1060a1 TH |
5910 | /* |
5911 | * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data | |
5912 | * definition in cgroup-defs.h. | |
5913 | */ | |
5914 | #ifdef CONFIG_SOCK_CGROUP_DATA | |
5915 | ||
5916 | #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID) | |
5917 | ||
3fa4cc9c | 5918 | DEFINE_SPINLOCK(cgroup_sk_update_lock); |
bd1060a1 TH |
5919 | static bool cgroup_sk_alloc_disabled __read_mostly; |
5920 | ||
5921 | void cgroup_sk_alloc_disable(void) | |
5922 | { | |
5923 | if (cgroup_sk_alloc_disabled) | |
5924 | return; | |
5925 | pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n"); | |
5926 | cgroup_sk_alloc_disabled = true; | |
5927 | } | |
5928 | ||
5929 | #else | |
5930 | ||
5931 | #define cgroup_sk_alloc_disabled false | |
5932 | ||
5933 | #endif | |
5934 | ||
5935 | void cgroup_sk_alloc(struct sock_cgroup_data *skcd) | |
5936 | { | |
5937 | if (cgroup_sk_alloc_disabled) | |
5938 | return; | |
5939 | ||
5940 | rcu_read_lock(); | |
5941 | ||
5942 | while (true) { | |
5943 | struct css_set *cset; | |
5944 | ||
5945 | cset = task_css_set(current); | |
5946 | if (likely(cgroup_tryget(cset->dfl_cgrp))) { | |
5947 | skcd->val = (unsigned long)cset->dfl_cgrp; | |
5948 | break; | |
5949 | } | |
5950 | cpu_relax(); | |
5951 | } | |
5952 | ||
5953 | rcu_read_unlock(); | |
5954 | } | |
5955 | ||
5956 | void cgroup_sk_free(struct sock_cgroup_data *skcd) | |
5957 | { | |
5958 | cgroup_put(sock_cgroup_ptr(skcd)); | |
5959 | } | |
5960 | ||
5961 | #endif /* CONFIG_SOCK_CGROUP_DATA */ | |
5962 | ||
fe693435 | 5963 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
5964 | static struct cgroup_subsys_state * |
5965 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
5966 | { |
5967 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5968 | ||
5969 | if (!css) | |
5970 | return ERR_PTR(-ENOMEM); | |
5971 | ||
5972 | return css; | |
5973 | } | |
5974 | ||
eb95419b | 5975 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 5976 | { |
eb95419b | 5977 | kfree(css); |
fe693435 PM |
5978 | } |
5979 | ||
182446d0 TH |
5980 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
5981 | struct cftype *cft) | |
fe693435 | 5982 | { |
182446d0 | 5983 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
5984 | } |
5985 | ||
182446d0 TH |
5986 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
5987 | struct cftype *cft) | |
fe693435 PM |
5988 | { |
5989 | return (u64)(unsigned long)current->cgroups; | |
5990 | } | |
5991 | ||
182446d0 | 5992 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 5993 | struct cftype *cft) |
fe693435 PM |
5994 | { |
5995 | u64 count; | |
5996 | ||
5997 | rcu_read_lock(); | |
a8ad805c | 5998 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
5999 | rcu_read_unlock(); |
6000 | return count; | |
6001 | } | |
6002 | ||
2da8ca82 | 6003 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 6004 | { |
69d0206c | 6005 | struct cgrp_cset_link *link; |
5abb8855 | 6006 | struct css_set *cset; |
e61734c5 TH |
6007 | char *name_buf; |
6008 | ||
6009 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
6010 | if (!name_buf) | |
6011 | return -ENOMEM; | |
7717f7ba | 6012 | |
f0d9a5f1 | 6013 | spin_lock_bh(&css_set_lock); |
7717f7ba | 6014 | rcu_read_lock(); |
5abb8855 | 6015 | cset = rcu_dereference(current->cgroups); |
69d0206c | 6016 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 6017 | struct cgroup *c = link->cgrp; |
7717f7ba | 6018 | |
a2dd4247 | 6019 | cgroup_name(c, name_buf, NAME_MAX + 1); |
2c6ab6d2 | 6020 | seq_printf(seq, "Root %d group %s\n", |
a2dd4247 | 6021 | c->root->hierarchy_id, name_buf); |
7717f7ba PM |
6022 | } |
6023 | rcu_read_unlock(); | |
f0d9a5f1 | 6024 | spin_unlock_bh(&css_set_lock); |
e61734c5 | 6025 | kfree(name_buf); |
7717f7ba PM |
6026 | return 0; |
6027 | } | |
6028 | ||
6029 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 6030 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 6031 | { |
2da8ca82 | 6032 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 6033 | struct cgrp_cset_link *link; |
7717f7ba | 6034 | |
f0d9a5f1 | 6035 | spin_lock_bh(&css_set_lock); |
182446d0 | 6036 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 6037 | struct css_set *cset = link->cset; |
7717f7ba PM |
6038 | struct task_struct *task; |
6039 | int count = 0; | |
c7561128 | 6040 | |
5abb8855 | 6041 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 6042 | |
5abb8855 | 6043 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
6044 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
6045 | goto overflow; | |
6046 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
6047 | } | |
6048 | ||
6049 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
6050 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
6051 | goto overflow; | |
6052 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 6053 | } |
c7561128 TH |
6054 | continue; |
6055 | overflow: | |
6056 | seq_puts(seq, " ...\n"); | |
7717f7ba | 6057 | } |
f0d9a5f1 | 6058 | spin_unlock_bh(&css_set_lock); |
7717f7ba PM |
6059 | return 0; |
6060 | } | |
6061 | ||
182446d0 | 6062 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 6063 | { |
27bd4dbb | 6064 | return (!cgroup_is_populated(css->cgroup) && |
a25eb52e | 6065 | !css_has_online_children(&css->cgroup->self)); |
fe693435 PM |
6066 | } |
6067 | ||
6068 | static struct cftype debug_files[] = { | |
fe693435 PM |
6069 | { |
6070 | .name = "taskcount", | |
6071 | .read_u64 = debug_taskcount_read, | |
6072 | }, | |
6073 | ||
6074 | { | |
6075 | .name = "current_css_set", | |
6076 | .read_u64 = current_css_set_read, | |
6077 | }, | |
6078 | ||
6079 | { | |
6080 | .name = "current_css_set_refcount", | |
6081 | .read_u64 = current_css_set_refcount_read, | |
6082 | }, | |
6083 | ||
7717f7ba PM |
6084 | { |
6085 | .name = "current_css_set_cg_links", | |
2da8ca82 | 6086 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
6087 | }, |
6088 | ||
6089 | { | |
6090 | .name = "cgroup_css_links", | |
2da8ca82 | 6091 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
6092 | }, |
6093 | ||
fe693435 PM |
6094 | { |
6095 | .name = "releasable", | |
6096 | .read_u64 = releasable_read, | |
6097 | }, | |
fe693435 | 6098 | |
4baf6e33 TH |
6099 | { } /* terminate */ |
6100 | }; | |
fe693435 | 6101 | |
073219e9 | 6102 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
6103 | .css_alloc = debug_css_alloc, |
6104 | .css_free = debug_css_free, | |
5577964e | 6105 | .legacy_cftypes = debug_files, |
fe693435 PM |
6106 | }; |
6107 | #endif /* CONFIG_CGROUP_DEBUG */ |