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 | ||
29 | #include <linux/cgroup.h> | |
2ce9738b | 30 | #include <linux/cred.h> |
c6d57f33 | 31 | #include <linux/ctype.h> |
ddbcc7e8 | 32 | #include <linux/errno.h> |
2ce9738b | 33 | #include <linux/init_task.h> |
ddbcc7e8 PM |
34 | #include <linux/kernel.h> |
35 | #include <linux/list.h> | |
36 | #include <linux/mm.h> | |
37 | #include <linux/mutex.h> | |
38 | #include <linux/mount.h> | |
39 | #include <linux/pagemap.h> | |
a424316c | 40 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
41 | #include <linux/rcupdate.h> |
42 | #include <linux/sched.h> | |
817929ec | 43 | #include <linux/backing-dev.h> |
ddbcc7e8 PM |
44 | #include <linux/seq_file.h> |
45 | #include <linux/slab.h> | |
46 | #include <linux/magic.h> | |
47 | #include <linux/spinlock.h> | |
48 | #include <linux/string.h> | |
bbcb81d0 | 49 | #include <linux/sort.h> |
81a6a5cd | 50 | #include <linux/kmod.h> |
e6a1105b | 51 | #include <linux/module.h> |
846c7bb0 BS |
52 | #include <linux/delayacct.h> |
53 | #include <linux/cgroupstats.h> | |
0ac801fe | 54 | #include <linux/hashtable.h> |
3f8206d4 | 55 | #include <linux/namei.h> |
096b7fe0 | 56 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 57 | #include <linux/idr.h> |
d1d9fd33 | 58 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
0dea1168 KS |
59 | #include <linux/eventfd.h> |
60 | #include <linux/poll.h> | |
081aa458 | 61 | #include <linux/flex_array.h> /* used in cgroup_attach_task */ |
c4c27fbd | 62 | #include <linux/kthread.h> |
846c7bb0 | 63 | |
60063497 | 64 | #include <linux/atomic.h> |
ddbcc7e8 | 65 | |
e25e2cbb TH |
66 | /* |
67 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
68 | * hierarchy must be performed while holding it. | |
69 | * | |
70 | * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify | |
71 | * cgroupfs_root of any cgroup hierarchy - subsys list, flags, | |
72 | * release_agent_path and so on. Modifying requires both cgroup_mutex and | |
73 | * cgroup_root_mutex. Readers can acquire either of the two. This is to | |
74 | * break the following locking order cycle. | |
75 | * | |
76 | * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem | |
77 | * B. namespace_sem -> cgroup_mutex | |
78 | * | |
79 | * B happens only through cgroup_show_options() and using cgroup_root_mutex | |
80 | * breaks it. | |
81 | */ | |
2219449a TH |
82 | #ifdef CONFIG_PROVE_RCU |
83 | DEFINE_MUTEX(cgroup_mutex); | |
84 | EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */ | |
85 | #else | |
81a6a5cd | 86 | static DEFINE_MUTEX(cgroup_mutex); |
2219449a TH |
87 | #endif |
88 | ||
e25e2cbb | 89 | static DEFINE_MUTEX(cgroup_root_mutex); |
81a6a5cd | 90 | |
aae8aab4 BB |
91 | /* |
92 | * Generate an array of cgroup subsystem pointers. At boot time, this is | |
be45c900 | 93 | * populated with the built in subsystems, and modular subsystems are |
aae8aab4 BB |
94 | * registered after that. The mutable section of this array is protected by |
95 | * cgroup_mutex. | |
96 | */ | |
80f4c877 | 97 | #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys, |
5fc0b025 | 98 | #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) |
aae8aab4 | 99 | static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { |
ddbcc7e8 PM |
100 | #include <linux/cgroup_subsys.h> |
101 | }; | |
102 | ||
ddbcc7e8 PM |
103 | /* |
104 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the | |
105 | * subsystems that are otherwise unattached - it never has more than a | |
106 | * single cgroup, and all tasks are part of that cgroup. | |
107 | */ | |
108 | static struct cgroupfs_root rootnode; | |
109 | ||
05ef1d7c TH |
110 | /* |
111 | * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. | |
112 | */ | |
113 | struct cfent { | |
114 | struct list_head node; | |
115 | struct dentry *dentry; | |
116 | struct cftype *type; | |
712317ad LZ |
117 | |
118 | /* file xattrs */ | |
119 | struct simple_xattrs xattrs; | |
05ef1d7c TH |
120 | }; |
121 | ||
38460b48 KH |
122 | /* |
123 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when | |
124 | * cgroup_subsys->use_id != 0. | |
125 | */ | |
126 | #define CSS_ID_MAX (65535) | |
127 | struct css_id { | |
128 | /* | |
129 | * The css to which this ID points. This pointer is set to valid value | |
130 | * after cgroup is populated. If cgroup is removed, this will be NULL. | |
131 | * This pointer is expected to be RCU-safe because destroy() | |
e9316080 TH |
132 | * is called after synchronize_rcu(). But for safe use, css_tryget() |
133 | * should be used for avoiding race. | |
38460b48 | 134 | */ |
2c392b8c | 135 | struct cgroup_subsys_state __rcu *css; |
38460b48 KH |
136 | /* |
137 | * ID of this css. | |
138 | */ | |
139 | unsigned short id; | |
140 | /* | |
141 | * Depth in hierarchy which this ID belongs to. | |
142 | */ | |
143 | unsigned short depth; | |
144 | /* | |
145 | * ID is freed by RCU. (and lookup routine is RCU safe.) | |
146 | */ | |
147 | struct rcu_head rcu_head; | |
148 | /* | |
149 | * Hierarchy of CSS ID belongs to. | |
150 | */ | |
151 | unsigned short stack[0]; /* Array of Length (depth+1) */ | |
152 | }; | |
153 | ||
0dea1168 | 154 | /* |
25985edc | 155 | * cgroup_event represents events which userspace want to receive. |
0dea1168 KS |
156 | */ |
157 | struct cgroup_event { | |
158 | /* | |
159 | * Cgroup which the event belongs to. | |
160 | */ | |
161 | struct cgroup *cgrp; | |
162 | /* | |
163 | * Control file which the event associated. | |
164 | */ | |
165 | struct cftype *cft; | |
166 | /* | |
167 | * eventfd to signal userspace about the event. | |
168 | */ | |
169 | struct eventfd_ctx *eventfd; | |
170 | /* | |
171 | * Each of these stored in a list by the cgroup. | |
172 | */ | |
173 | struct list_head list; | |
174 | /* | |
175 | * All fields below needed to unregister event when | |
176 | * userspace closes eventfd. | |
177 | */ | |
178 | poll_table pt; | |
179 | wait_queue_head_t *wqh; | |
180 | wait_queue_t wait; | |
181 | struct work_struct remove; | |
182 | }; | |
38460b48 | 183 | |
ddbcc7e8 PM |
184 | /* The list of hierarchy roots */ |
185 | ||
186 | static LIST_HEAD(roots); | |
817929ec | 187 | static int root_count; |
ddbcc7e8 | 188 | |
54e7b4eb TH |
189 | /* |
190 | * Hierarchy ID allocation and mapping. It follows the same exclusion | |
191 | * rules as other root ops - both cgroup_mutex and cgroup_root_mutex for | |
192 | * writes, either for reads. | |
193 | */ | |
1a574231 | 194 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 195 | |
ddbcc7e8 PM |
196 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ |
197 | #define dummytop (&rootnode.top_cgroup) | |
198 | ||
65dff759 LZ |
199 | static struct cgroup_name root_cgroup_name = { .name = "/" }; |
200 | ||
794611a1 LZ |
201 | /* |
202 | * Assign a monotonically increasing serial number to cgroups. It | |
203 | * guarantees cgroups with bigger numbers are newer than those with smaller | |
204 | * numbers. Also, as cgroups are always appended to the parent's | |
205 | * ->children list, it guarantees that sibling cgroups are always sorted in | |
206 | * the ascending serial number order on the list. | |
207 | */ | |
208 | static atomic64_t cgroup_serial_nr_cursor = ATOMIC64_INIT(0); | |
209 | ||
ddbcc7e8 | 210 | /* This flag indicates whether tasks in the fork and exit paths should |
a043e3b2 LZ |
211 | * check for fork/exit handlers to call. This avoids us having to do |
212 | * extra work in the fork/exit path if none of the subsystems need to | |
213 | * be called. | |
ddbcc7e8 | 214 | */ |
8947f9d5 | 215 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 216 | |
ea15f8cc | 217 | static void cgroup_offline_fn(struct work_struct *work); |
42809dd4 | 218 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
879a3d9d G |
219 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
220 | struct cftype cfts[], bool is_add); | |
42809dd4 | 221 | |
ddbcc7e8 | 222 | /* convenient tests for these bits */ |
54766d4a | 223 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 224 | { |
54766d4a | 225 | return test_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 PM |
226 | } |
227 | ||
78574cf9 LZ |
228 | /** |
229 | * cgroup_is_descendant - test ancestry | |
230 | * @cgrp: the cgroup to be tested | |
231 | * @ancestor: possible ancestor of @cgrp | |
232 | * | |
233 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
234 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
235 | * and @ancestor are accessible. | |
236 | */ | |
237 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
238 | { | |
239 | while (cgrp) { | |
240 | if (cgrp == ancestor) | |
241 | return true; | |
242 | cgrp = cgrp->parent; | |
243 | } | |
244 | return false; | |
245 | } | |
246 | EXPORT_SYMBOL_GPL(cgroup_is_descendant); | |
ddbcc7e8 | 247 | |
e9685a03 | 248 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
249 | { |
250 | const int bits = | |
bd89aabc PM |
251 | (1 << CGRP_RELEASABLE) | |
252 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
253 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
254 | } |
255 | ||
e9685a03 | 256 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 257 | { |
bd89aabc | 258 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
259 | } |
260 | ||
ddbcc7e8 PM |
261 | /* |
262 | * for_each_subsys() allows you to iterate on each subsystem attached to | |
263 | * an active hierarchy | |
264 | */ | |
265 | #define for_each_subsys(_root, _ss) \ | |
266 | list_for_each_entry(_ss, &_root->subsys_list, sibling) | |
267 | ||
e5f6a860 LZ |
268 | /* for_each_active_root() allows you to iterate across the active hierarchies */ |
269 | #define for_each_active_root(_root) \ | |
ddbcc7e8 PM |
270 | list_for_each_entry(_root, &roots, root_list) |
271 | ||
f6ea9372 TH |
272 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
273 | { | |
274 | return dentry->d_fsdata; | |
275 | } | |
276 | ||
05ef1d7c | 277 | static inline struct cfent *__d_cfe(struct dentry *dentry) |
f6ea9372 TH |
278 | { |
279 | return dentry->d_fsdata; | |
280 | } | |
281 | ||
05ef1d7c TH |
282 | static inline struct cftype *__d_cft(struct dentry *dentry) |
283 | { | |
284 | return __d_cfe(dentry)->type; | |
285 | } | |
286 | ||
7ae1bad9 TH |
287 | /** |
288 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
289 | * @cgrp: the cgroup to be checked for liveness | |
290 | * | |
47cfcd09 TH |
291 | * On success, returns true; the mutex should be later unlocked. On |
292 | * failure returns false with no lock held. | |
7ae1bad9 | 293 | */ |
b9777cf8 | 294 | static bool cgroup_lock_live_group(struct cgroup *cgrp) |
7ae1bad9 TH |
295 | { |
296 | mutex_lock(&cgroup_mutex); | |
54766d4a | 297 | if (cgroup_is_dead(cgrp)) { |
7ae1bad9 TH |
298 | mutex_unlock(&cgroup_mutex); |
299 | return false; | |
300 | } | |
301 | return true; | |
302 | } | |
7ae1bad9 | 303 | |
81a6a5cd PM |
304 | /* the list of cgroups eligible for automatic release. Protected by |
305 | * release_list_lock */ | |
306 | static LIST_HEAD(release_list); | |
cdcc136f | 307 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
308 | static void cgroup_release_agent(struct work_struct *work); |
309 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 310 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 311 | |
69d0206c TH |
312 | /* |
313 | * A cgroup can be associated with multiple css_sets as different tasks may | |
314 | * belong to different cgroups on different hierarchies. In the other | |
315 | * direction, a css_set is naturally associated with multiple cgroups. | |
316 | * This M:N relationship is represented by the following link structure | |
317 | * which exists for each association and allows traversing the associations | |
318 | * from both sides. | |
319 | */ | |
320 | struct cgrp_cset_link { | |
321 | /* the cgroup and css_set this link associates */ | |
322 | struct cgroup *cgrp; | |
323 | struct css_set *cset; | |
324 | ||
325 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
326 | struct list_head cset_link; | |
327 | ||
328 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
329 | struct list_head cgrp_link; | |
817929ec PM |
330 | }; |
331 | ||
332 | /* The default css_set - used by init and its children prior to any | |
333 | * hierarchies being mounted. It contains a pointer to the root state | |
334 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
335 | * reference-counted, to improve performance when child cgroups | |
336 | * haven't been created. | |
337 | */ | |
338 | ||
339 | static struct css_set init_css_set; | |
69d0206c | 340 | static struct cgrp_cset_link init_cgrp_cset_link; |
817929ec | 341 | |
e6a1105b BB |
342 | static int cgroup_init_idr(struct cgroup_subsys *ss, |
343 | struct cgroup_subsys_state *css); | |
38460b48 | 344 | |
817929ec PM |
345 | /* css_set_lock protects the list of css_set objects, and the |
346 | * chain of tasks off each css_set. Nests outside task->alloc_lock | |
347 | * due to cgroup_iter_start() */ | |
348 | static DEFINE_RWLOCK(css_set_lock); | |
349 | static int css_set_count; | |
350 | ||
7717f7ba PM |
351 | /* |
352 | * hash table for cgroup groups. This improves the performance to find | |
353 | * an existing css_set. This hash doesn't (currently) take into | |
354 | * account cgroups in empty hierarchies. | |
355 | */ | |
472b1053 | 356 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 357 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 358 | |
0ac801fe | 359 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 LZ |
360 | { |
361 | int i; | |
0ac801fe | 362 | unsigned long key = 0UL; |
472b1053 LZ |
363 | |
364 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) | |
0ac801fe LZ |
365 | key += (unsigned long)css[i]; |
366 | key = (key >> 16) ^ key; | |
472b1053 | 367 | |
0ac801fe | 368 | return key; |
472b1053 LZ |
369 | } |
370 | ||
817929ec PM |
371 | /* We don't maintain the lists running through each css_set to its |
372 | * task until after the first call to cgroup_iter_start(). This | |
373 | * reduces the fork()/exit() overhead for people who have cgroups | |
374 | * compiled into their kernel but not actually in use */ | |
8947f9d5 | 375 | static int use_task_css_set_links __read_mostly; |
817929ec | 376 | |
5abb8855 | 377 | static void __put_css_set(struct css_set *cset, int taskexit) |
b4f48b63 | 378 | { |
69d0206c | 379 | struct cgrp_cset_link *link, *tmp_link; |
5abb8855 | 380 | |
146aa1bd LJ |
381 | /* |
382 | * Ensure that the refcount doesn't hit zero while any readers | |
383 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
384 | * rwlock | |
385 | */ | |
5abb8855 | 386 | if (atomic_add_unless(&cset->refcount, -1, 1)) |
146aa1bd LJ |
387 | return; |
388 | write_lock(&css_set_lock); | |
5abb8855 | 389 | if (!atomic_dec_and_test(&cset->refcount)) { |
146aa1bd LJ |
390 | write_unlock(&css_set_lock); |
391 | return; | |
392 | } | |
81a6a5cd | 393 | |
2c6ab6d2 | 394 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
5abb8855 | 395 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
396 | css_set_count--; |
397 | ||
69d0206c | 398 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 399 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 400 | |
69d0206c TH |
401 | list_del(&link->cset_link); |
402 | list_del(&link->cgrp_link); | |
71b5707e | 403 | |
ddd69148 | 404 | /* @cgrp can't go away while we're holding css_set_lock */ |
6f3d828f | 405 | if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) { |
81a6a5cd | 406 | if (taskexit) |
bd89aabc PM |
407 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
408 | check_for_release(cgrp); | |
81a6a5cd | 409 | } |
2c6ab6d2 PM |
410 | |
411 | kfree(link); | |
81a6a5cd | 412 | } |
2c6ab6d2 PM |
413 | |
414 | write_unlock(&css_set_lock); | |
5abb8855 | 415 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
416 | } |
417 | ||
817929ec PM |
418 | /* |
419 | * refcounted get/put for css_set objects | |
420 | */ | |
5abb8855 | 421 | static inline void get_css_set(struct css_set *cset) |
817929ec | 422 | { |
5abb8855 | 423 | atomic_inc(&cset->refcount); |
817929ec PM |
424 | } |
425 | ||
5abb8855 | 426 | static inline void put_css_set(struct css_set *cset) |
817929ec | 427 | { |
5abb8855 | 428 | __put_css_set(cset, 0); |
817929ec PM |
429 | } |
430 | ||
5abb8855 | 431 | static inline void put_css_set_taskexit(struct css_set *cset) |
81a6a5cd | 432 | { |
5abb8855 | 433 | __put_css_set(cset, 1); |
81a6a5cd PM |
434 | } |
435 | ||
7717f7ba PM |
436 | /* |
437 | * compare_css_sets - helper function for find_existing_css_set(). | |
5abb8855 TH |
438 | * @cset: candidate css_set being tested |
439 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
440 | * @new_cgrp: cgroup that's being entered by the task |
441 | * @template: desired set of css pointers in css_set (pre-calculated) | |
442 | * | |
443 | * Returns true if "cg" matches "old_cg" except for the hierarchy | |
444 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". | |
445 | */ | |
5abb8855 TH |
446 | static bool compare_css_sets(struct css_set *cset, |
447 | struct css_set *old_cset, | |
7717f7ba PM |
448 | struct cgroup *new_cgrp, |
449 | struct cgroup_subsys_state *template[]) | |
450 | { | |
451 | struct list_head *l1, *l2; | |
452 | ||
5abb8855 | 453 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) { |
7717f7ba PM |
454 | /* Not all subsystems matched */ |
455 | return false; | |
456 | } | |
457 | ||
458 | /* | |
459 | * Compare cgroup pointers in order to distinguish between | |
460 | * different cgroups in heirarchies with no subsystems. We | |
461 | * could get by with just this check alone (and skip the | |
462 | * memcmp above) but on most setups the memcmp check will | |
463 | * avoid the need for this more expensive check on almost all | |
464 | * candidates. | |
465 | */ | |
466 | ||
69d0206c TH |
467 | l1 = &cset->cgrp_links; |
468 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 469 | while (1) { |
69d0206c | 470 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 471 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
472 | |
473 | l1 = l1->next; | |
474 | l2 = l2->next; | |
475 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
476 | if (l1 == &cset->cgrp_links) { |
477 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
478 | break; |
479 | } else { | |
69d0206c | 480 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
481 | } |
482 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
483 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
484 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
485 | cgrp1 = link1->cgrp; | |
486 | cgrp2 = link2->cgrp; | |
7717f7ba | 487 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 488 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
489 | |
490 | /* | |
491 | * If this hierarchy is the hierarchy of the cgroup | |
492 | * that's changing, then we need to check that this | |
493 | * css_set points to the new cgroup; if it's any other | |
494 | * hierarchy, then this css_set should point to the | |
495 | * same cgroup as the old css_set. | |
496 | */ | |
5abb8855 TH |
497 | if (cgrp1->root == new_cgrp->root) { |
498 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
499 | return false; |
500 | } else { | |
5abb8855 | 501 | if (cgrp1 != cgrp2) |
7717f7ba PM |
502 | return false; |
503 | } | |
504 | } | |
505 | return true; | |
506 | } | |
507 | ||
817929ec PM |
508 | /* |
509 | * find_existing_css_set() is a helper for | |
510 | * find_css_set(), and checks to see whether an existing | |
472b1053 | 511 | * css_set is suitable. |
817929ec PM |
512 | * |
513 | * oldcg: the cgroup group that we're using before the cgroup | |
514 | * transition | |
515 | * | |
bd89aabc | 516 | * cgrp: the cgroup that we're moving into |
817929ec PM |
517 | * |
518 | * template: location in which to build the desired set of subsystem | |
519 | * state objects for the new cgroup group | |
520 | */ | |
5abb8855 TH |
521 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
522 | struct cgroup *cgrp, | |
523 | struct cgroup_subsys_state *template[]) | |
b4f48b63 PM |
524 | { |
525 | int i; | |
bd89aabc | 526 | struct cgroupfs_root *root = cgrp->root; |
5abb8855 | 527 | struct css_set *cset; |
0ac801fe | 528 | unsigned long key; |
817929ec | 529 | |
aae8aab4 BB |
530 | /* |
531 | * Build the set of subsystem state objects that we want to see in the | |
532 | * new css_set. while subsystems can change globally, the entries here | |
533 | * won't change, so no need for locking. | |
534 | */ | |
817929ec | 535 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
a1a71b45 | 536 | if (root->subsys_mask & (1UL << i)) { |
817929ec PM |
537 | /* Subsystem is in this hierarchy. So we want |
538 | * the subsystem state from the new | |
539 | * cgroup */ | |
bd89aabc | 540 | template[i] = cgrp->subsys[i]; |
817929ec PM |
541 | } else { |
542 | /* Subsystem is not in this hierarchy, so we | |
543 | * don't want to change the subsystem state */ | |
5abb8855 | 544 | template[i] = old_cset->subsys[i]; |
817929ec PM |
545 | } |
546 | } | |
547 | ||
0ac801fe | 548 | key = css_set_hash(template); |
5abb8855 TH |
549 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
550 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
551 | continue; |
552 | ||
553 | /* This css_set matches what we need */ | |
5abb8855 | 554 | return cset; |
472b1053 | 555 | } |
817929ec PM |
556 | |
557 | /* No existing cgroup group matched */ | |
558 | return NULL; | |
559 | } | |
560 | ||
69d0206c | 561 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 562 | { |
69d0206c | 563 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 564 | |
69d0206c TH |
565 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
566 | list_del(&link->cset_link); | |
36553434 LZ |
567 | kfree(link); |
568 | } | |
569 | } | |
570 | ||
69d0206c TH |
571 | /** |
572 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
573 | * @count: the number of links to allocate | |
574 | * @tmp_links: list_head the allocated links are put on | |
575 | * | |
576 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
577 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 578 | */ |
69d0206c | 579 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 580 | { |
69d0206c | 581 | struct cgrp_cset_link *link; |
817929ec | 582 | int i; |
69d0206c TH |
583 | |
584 | INIT_LIST_HEAD(tmp_links); | |
585 | ||
817929ec | 586 | for (i = 0; i < count; i++) { |
f4f4be2b | 587 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 588 | if (!link) { |
69d0206c | 589 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
590 | return -ENOMEM; |
591 | } | |
69d0206c | 592 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
593 | } |
594 | return 0; | |
595 | } | |
596 | ||
c12f65d4 LZ |
597 | /** |
598 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 599 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 600 | * @cset: the css_set to be linked |
c12f65d4 LZ |
601 | * @cgrp: the destination cgroup |
602 | */ | |
69d0206c TH |
603 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
604 | struct cgroup *cgrp) | |
c12f65d4 | 605 | { |
69d0206c | 606 | struct cgrp_cset_link *link; |
c12f65d4 | 607 | |
69d0206c TH |
608 | BUG_ON(list_empty(tmp_links)); |
609 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); | |
610 | link->cset = cset; | |
7717f7ba | 611 | link->cgrp = cgrp; |
69d0206c | 612 | list_move(&link->cset_link, &cgrp->cset_links); |
7717f7ba PM |
613 | /* |
614 | * Always add links to the tail of the list so that the list | |
615 | * is sorted by order of hierarchy creation | |
616 | */ | |
69d0206c | 617 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
618 | } |
619 | ||
817929ec PM |
620 | /* |
621 | * find_css_set() takes an existing cgroup group and a | |
622 | * cgroup object, and returns a css_set object that's | |
623 | * equivalent to the old group, but with the given cgroup | |
624 | * substituted into the appropriate hierarchy. Must be called with | |
625 | * cgroup_mutex held | |
626 | */ | |
5abb8855 TH |
627 | static struct css_set *find_css_set(struct css_set *old_cset, |
628 | struct cgroup *cgrp) | |
817929ec | 629 | { |
5abb8855 | 630 | struct css_set *cset; |
817929ec | 631 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; |
69d0206c TH |
632 | struct list_head tmp_links; |
633 | struct cgrp_cset_link *link; | |
0ac801fe | 634 | unsigned long key; |
472b1053 | 635 | |
817929ec PM |
636 | /* First see if we already have a cgroup group that matches |
637 | * the desired set */ | |
7e9abd89 | 638 | read_lock(&css_set_lock); |
5abb8855 TH |
639 | cset = find_existing_css_set(old_cset, cgrp, template); |
640 | if (cset) | |
641 | get_css_set(cset); | |
7e9abd89 | 642 | read_unlock(&css_set_lock); |
817929ec | 643 | |
5abb8855 TH |
644 | if (cset) |
645 | return cset; | |
817929ec | 646 | |
f4f4be2b | 647 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 648 | if (!cset) |
817929ec PM |
649 | return NULL; |
650 | ||
69d0206c TH |
651 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
652 | if (allocate_cgrp_cset_links(root_count, &tmp_links) < 0) { | |
5abb8855 | 653 | kfree(cset); |
817929ec PM |
654 | return NULL; |
655 | } | |
656 | ||
5abb8855 | 657 | atomic_set(&cset->refcount, 1); |
69d0206c | 658 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 TH |
659 | INIT_LIST_HEAD(&cset->tasks); |
660 | INIT_HLIST_NODE(&cset->hlist); | |
817929ec PM |
661 | |
662 | /* Copy the set of subsystem state objects generated in | |
663 | * find_existing_css_set() */ | |
5abb8855 | 664 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec PM |
665 | |
666 | write_lock(&css_set_lock); | |
667 | /* Add reference counts and links from the new css_set. */ | |
69d0206c | 668 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 669 | struct cgroup *c = link->cgrp; |
69d0206c | 670 | |
7717f7ba PM |
671 | if (c->root == cgrp->root) |
672 | c = cgrp; | |
69d0206c | 673 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 674 | } |
817929ec | 675 | |
69d0206c | 676 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 677 | |
817929ec | 678 | css_set_count++; |
472b1053 LZ |
679 | |
680 | /* Add this cgroup group to the hash table */ | |
5abb8855 TH |
681 | key = css_set_hash(cset->subsys); |
682 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 683 | |
817929ec PM |
684 | write_unlock(&css_set_lock); |
685 | ||
5abb8855 | 686 | return cset; |
b4f48b63 PM |
687 | } |
688 | ||
7717f7ba PM |
689 | /* |
690 | * Return the cgroup for "task" from the given hierarchy. Must be | |
691 | * called with cgroup_mutex held. | |
692 | */ | |
693 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
694 | struct cgroupfs_root *root) | |
695 | { | |
5abb8855 | 696 | struct css_set *cset; |
7717f7ba PM |
697 | struct cgroup *res = NULL; |
698 | ||
699 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
700 | read_lock(&css_set_lock); | |
701 | /* | |
702 | * No need to lock the task - since we hold cgroup_mutex the | |
703 | * task can't change groups, so the only thing that can happen | |
704 | * is that it exits and its css is set back to init_css_set. | |
705 | */ | |
5abb8855 TH |
706 | cset = task->cgroups; |
707 | if (cset == &init_css_set) { | |
7717f7ba PM |
708 | res = &root->top_cgroup; |
709 | } else { | |
69d0206c TH |
710 | struct cgrp_cset_link *link; |
711 | ||
712 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 713 | struct cgroup *c = link->cgrp; |
69d0206c | 714 | |
7717f7ba PM |
715 | if (c->root == root) { |
716 | res = c; | |
717 | break; | |
718 | } | |
719 | } | |
720 | } | |
721 | read_unlock(&css_set_lock); | |
722 | BUG_ON(!res); | |
723 | return res; | |
724 | } | |
725 | ||
ddbcc7e8 PM |
726 | /* |
727 | * There is one global cgroup mutex. We also require taking | |
728 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
729 | * See "The task_lock() exception", at the end of this comment. | |
730 | * | |
731 | * A task must hold cgroup_mutex to modify cgroups. | |
732 | * | |
733 | * Any task can increment and decrement the count field without lock. | |
734 | * So in general, code holding cgroup_mutex can't rely on the count | |
735 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 736 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
737 | * means that no tasks are currently attached, therefore there is no |
738 | * way a task attached to that cgroup can fork (the other way to | |
739 | * increment the count). So code holding cgroup_mutex can safely | |
740 | * assume that if the count is zero, it will stay zero. Similarly, if | |
741 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
742 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
743 | * needs that mutex. | |
744 | * | |
ddbcc7e8 PM |
745 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
746 | * (usually) take cgroup_mutex. These are the two most performance | |
747 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
748 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
749 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
750 | * to the release agent with the name of the cgroup (path relative to |
751 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
752 | * |
753 | * A cgroup can only be deleted if both its 'count' of using tasks | |
754 | * is zero, and its list of 'children' cgroups is empty. Since all | |
755 | * tasks in the system use _some_ cgroup, and since there is always at | |
756 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
757 | * always has either children cgroups and/or using tasks. So we don't | |
758 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
759 | * | |
760 | * The task_lock() exception | |
761 | * | |
762 | * The need for this exception arises from the action of | |
d0b2fdd2 | 763 | * cgroup_attach_task(), which overwrites one task's cgroup pointer with |
a043e3b2 | 764 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
765 | * several performance critical places that need to reference |
766 | * task->cgroup without the expense of grabbing a system global | |
767 | * mutex. Therefore except as noted below, when dereferencing or, as | |
d0b2fdd2 | 768 | * in cgroup_attach_task(), modifying a task's cgroup pointer we use |
ddbcc7e8 PM |
769 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
770 | * the task_struct routinely used for such matters. | |
771 | * | |
772 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 773 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
774 | */ |
775 | ||
ddbcc7e8 PM |
776 | /* |
777 | * A couple of forward declarations required, due to cyclic reference loop: | |
778 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
779 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
780 | * -> cgroup_mkdir. | |
781 | */ | |
782 | ||
18bb1db3 | 783 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); |
00cd8dd3 | 784 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int); |
ddbcc7e8 | 785 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
13af07df AR |
786 | static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, |
787 | unsigned long subsys_mask); | |
6e1d5dcc | 788 | static const struct inode_operations cgroup_dir_inode_operations; |
828c0950 | 789 | static const struct file_operations proc_cgroupstats_operations; |
a424316c PM |
790 | |
791 | static struct backing_dev_info cgroup_backing_dev_info = { | |
d993831f | 792 | .name = "cgroup", |
e4ad08fe | 793 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
a424316c | 794 | }; |
ddbcc7e8 | 795 | |
38460b48 KH |
796 | static int alloc_css_id(struct cgroup_subsys *ss, |
797 | struct cgroup *parent, struct cgroup *child); | |
798 | ||
a5e7ed32 | 799 | static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) |
ddbcc7e8 PM |
800 | { |
801 | struct inode *inode = new_inode(sb); | |
ddbcc7e8 PM |
802 | |
803 | if (inode) { | |
85fe4025 | 804 | inode->i_ino = get_next_ino(); |
ddbcc7e8 | 805 | inode->i_mode = mode; |
76aac0e9 DH |
806 | inode->i_uid = current_fsuid(); |
807 | inode->i_gid = current_fsgid(); | |
ddbcc7e8 PM |
808 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
809 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
810 | } | |
811 | return inode; | |
812 | } | |
813 | ||
65dff759 LZ |
814 | static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry) |
815 | { | |
816 | struct cgroup_name *name; | |
817 | ||
818 | name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL); | |
819 | if (!name) | |
820 | return NULL; | |
821 | strcpy(name->name, dentry->d_name.name); | |
822 | return name; | |
823 | } | |
824 | ||
be445626 LZ |
825 | static void cgroup_free_fn(struct work_struct *work) |
826 | { | |
ea15f8cc | 827 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); |
be445626 LZ |
828 | struct cgroup_subsys *ss; |
829 | ||
830 | mutex_lock(&cgroup_mutex); | |
831 | /* | |
832 | * Release the subsystem state objects. | |
833 | */ | |
834 | for_each_subsys(cgrp->root, ss) | |
835 | ss->css_free(cgrp); | |
836 | ||
837 | cgrp->root->number_of_cgroups--; | |
838 | mutex_unlock(&cgroup_mutex); | |
839 | ||
415cf07a LZ |
840 | /* |
841 | * We get a ref to the parent's dentry, and put the ref when | |
842 | * this cgroup is being freed, so it's guaranteed that the | |
843 | * parent won't be destroyed before its children. | |
844 | */ | |
845 | dput(cgrp->parent->dentry); | |
846 | ||
cc20e01c LZ |
847 | ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); |
848 | ||
be445626 LZ |
849 | /* |
850 | * Drop the active superblock reference that we took when we | |
cc20e01c LZ |
851 | * created the cgroup. This will free cgrp->root, if we are |
852 | * holding the last reference to @sb. | |
be445626 LZ |
853 | */ |
854 | deactivate_super(cgrp->root->sb); | |
855 | ||
856 | /* | |
857 | * if we're getting rid of the cgroup, refcount should ensure | |
858 | * that there are no pidlists left. | |
859 | */ | |
860 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
861 | ||
862 | simple_xattrs_free(&cgrp->xattrs); | |
863 | ||
65dff759 | 864 | kfree(rcu_dereference_raw(cgrp->name)); |
be445626 LZ |
865 | kfree(cgrp); |
866 | } | |
867 | ||
868 | static void cgroup_free_rcu(struct rcu_head *head) | |
869 | { | |
870 | struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); | |
871 | ||
ea15f8cc TH |
872 | INIT_WORK(&cgrp->destroy_work, cgroup_free_fn); |
873 | schedule_work(&cgrp->destroy_work); | |
be445626 LZ |
874 | } |
875 | ||
ddbcc7e8 PM |
876 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
877 | { | |
878 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
879 | if (S_ISDIR(inode->i_mode)) { | |
bd89aabc | 880 | struct cgroup *cgrp = dentry->d_fsdata; |
be445626 | 881 | |
54766d4a | 882 | BUG_ON(!(cgroup_is_dead(cgrp))); |
be445626 | 883 | call_rcu(&cgrp->rcu_head, cgroup_free_rcu); |
05ef1d7c TH |
884 | } else { |
885 | struct cfent *cfe = __d_cfe(dentry); | |
886 | struct cgroup *cgrp = dentry->d_parent->d_fsdata; | |
887 | ||
888 | WARN_ONCE(!list_empty(&cfe->node) && | |
889 | cgrp != &cgrp->root->top_cgroup, | |
890 | "cfe still linked for %s\n", cfe->type->name); | |
712317ad | 891 | simple_xattrs_free(&cfe->xattrs); |
05ef1d7c | 892 | kfree(cfe); |
ddbcc7e8 PM |
893 | } |
894 | iput(inode); | |
895 | } | |
896 | ||
c72a04e3 AV |
897 | static int cgroup_delete(const struct dentry *d) |
898 | { | |
899 | return 1; | |
900 | } | |
901 | ||
ddbcc7e8 PM |
902 | static void remove_dir(struct dentry *d) |
903 | { | |
904 | struct dentry *parent = dget(d->d_parent); | |
905 | ||
906 | d_delete(d); | |
907 | simple_rmdir(parent->d_inode, d); | |
908 | dput(parent); | |
909 | } | |
910 | ||
2739d3cc | 911 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c TH |
912 | { |
913 | struct cfent *cfe; | |
914 | ||
915 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); | |
916 | lockdep_assert_held(&cgroup_mutex); | |
917 | ||
2739d3cc LZ |
918 | /* |
919 | * If we're doing cleanup due to failure of cgroup_create(), | |
920 | * the corresponding @cfe may not exist. | |
921 | */ | |
05ef1d7c TH |
922 | list_for_each_entry(cfe, &cgrp->files, node) { |
923 | struct dentry *d = cfe->dentry; | |
924 | ||
925 | if (cft && cfe->type != cft) | |
926 | continue; | |
927 | ||
928 | dget(d); | |
929 | d_delete(d); | |
ce27e317 | 930 | simple_unlink(cgrp->dentry->d_inode, d); |
05ef1d7c TH |
931 | list_del_init(&cfe->node); |
932 | dput(d); | |
933 | ||
2739d3cc | 934 | break; |
ddbcc7e8 | 935 | } |
05ef1d7c TH |
936 | } |
937 | ||
13af07df AR |
938 | /** |
939 | * cgroup_clear_directory - selective removal of base and subsystem files | |
940 | * @dir: directory containing the files | |
941 | * @base_files: true if the base files should be removed | |
942 | * @subsys_mask: mask of the subsystem ids whose files should be removed | |
943 | */ | |
944 | static void cgroup_clear_directory(struct dentry *dir, bool base_files, | |
945 | unsigned long subsys_mask) | |
05ef1d7c TH |
946 | { |
947 | struct cgroup *cgrp = __d_cgrp(dir); | |
13af07df | 948 | struct cgroup_subsys *ss; |
05ef1d7c | 949 | |
13af07df AR |
950 | for_each_subsys(cgrp->root, ss) { |
951 | struct cftype_set *set; | |
952 | if (!test_bit(ss->subsys_id, &subsys_mask)) | |
953 | continue; | |
954 | list_for_each_entry(set, &ss->cftsets, node) | |
879a3d9d | 955 | cgroup_addrm_files(cgrp, NULL, set->cfts, false); |
13af07df AR |
956 | } |
957 | if (base_files) { | |
958 | while (!list_empty(&cgrp->files)) | |
959 | cgroup_rm_file(cgrp, NULL); | |
960 | } | |
ddbcc7e8 PM |
961 | } |
962 | ||
963 | /* | |
964 | * NOTE : the dentry must have been dget()'ed | |
965 | */ | |
966 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
967 | { | |
2fd6b7f5 | 968 | struct dentry *parent; |
13af07df | 969 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
2fd6b7f5 | 970 | |
a1a71b45 | 971 | cgroup_clear_directory(dentry, true, root->subsys_mask); |
ddbcc7e8 | 972 | |
2fd6b7f5 NP |
973 | parent = dentry->d_parent; |
974 | spin_lock(&parent->d_lock); | |
3ec762ad | 975 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
ddbcc7e8 | 976 | list_del_init(&dentry->d_u.d_child); |
2fd6b7f5 NP |
977 | spin_unlock(&dentry->d_lock); |
978 | spin_unlock(&parent->d_lock); | |
ddbcc7e8 PM |
979 | remove_dir(dentry); |
980 | } | |
981 | ||
aae8aab4 | 982 | /* |
cf5d5941 BB |
983 | * Call with cgroup_mutex held. Drops reference counts on modules, including |
984 | * any duplicate ones that parse_cgroupfs_options took. If this function | |
985 | * returns an error, no reference counts are touched. | |
aae8aab4 | 986 | */ |
ddbcc7e8 | 987 | static int rebind_subsystems(struct cgroupfs_root *root, |
a1a71b45 | 988 | unsigned long final_subsys_mask) |
ddbcc7e8 | 989 | { |
a1a71b45 | 990 | unsigned long added_mask, removed_mask; |
bd89aabc | 991 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
992 | int i; |
993 | ||
aae8aab4 | 994 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
e25e2cbb | 995 | BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); |
aae8aab4 | 996 | |
a1a71b45 AR |
997 | removed_mask = root->actual_subsys_mask & ~final_subsys_mask; |
998 | added_mask = final_subsys_mask & ~root->actual_subsys_mask; | |
ddbcc7e8 PM |
999 | /* Check that any added subsystems are currently free */ |
1000 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
8d53d55d | 1001 | unsigned long bit = 1UL << i; |
ddbcc7e8 | 1002 | struct cgroup_subsys *ss = subsys[i]; |
a1a71b45 | 1003 | if (!(bit & added_mask)) |
ddbcc7e8 | 1004 | continue; |
aae8aab4 BB |
1005 | /* |
1006 | * Nobody should tell us to do a subsys that doesn't exist: | |
1007 | * parse_cgroupfs_options should catch that case and refcounts | |
1008 | * ensure that subsystems won't disappear once selected. | |
1009 | */ | |
1010 | BUG_ON(ss == NULL); | |
ddbcc7e8 PM |
1011 | if (ss->root != &rootnode) { |
1012 | /* Subsystem isn't free */ | |
1013 | return -EBUSY; | |
1014 | } | |
1015 | } | |
1016 | ||
1017 | /* Currently we don't handle adding/removing subsystems when | |
1018 | * any child cgroups exist. This is theoretically supportable | |
1019 | * but involves complex error handling, so it's being left until | |
1020 | * later */ | |
307257cf | 1021 | if (root->number_of_cgroups > 1) |
ddbcc7e8 PM |
1022 | return -EBUSY; |
1023 | ||
1024 | /* Process each subsystem */ | |
1025 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1026 | struct cgroup_subsys *ss = subsys[i]; | |
1027 | unsigned long bit = 1UL << i; | |
a1a71b45 | 1028 | if (bit & added_mask) { |
ddbcc7e8 | 1029 | /* We're binding this subsystem to this hierarchy */ |
aae8aab4 | 1030 | BUG_ON(ss == NULL); |
bd89aabc | 1031 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1032 | BUG_ON(!dummytop->subsys[i]); |
1033 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); | |
bd89aabc PM |
1034 | cgrp->subsys[i] = dummytop->subsys[i]; |
1035 | cgrp->subsys[i]->cgroup = cgrp; | |
33a68ac1 | 1036 | list_move(&ss->sibling, &root->subsys_list); |
b2aa30f7 | 1037 | ss->root = root; |
ddbcc7e8 | 1038 | if (ss->bind) |
761b3ef5 | 1039 | ss->bind(cgrp); |
cf5d5941 | 1040 | /* refcount was already taken, and we're keeping it */ |
a1a71b45 | 1041 | } else if (bit & removed_mask) { |
ddbcc7e8 | 1042 | /* We're removing this subsystem */ |
aae8aab4 | 1043 | BUG_ON(ss == NULL); |
bd89aabc PM |
1044 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
1045 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); | |
ddbcc7e8 | 1046 | if (ss->bind) |
761b3ef5 | 1047 | ss->bind(dummytop); |
ddbcc7e8 | 1048 | dummytop->subsys[i]->cgroup = dummytop; |
bd89aabc | 1049 | cgrp->subsys[i] = NULL; |
b2aa30f7 | 1050 | subsys[i]->root = &rootnode; |
33a68ac1 | 1051 | list_move(&ss->sibling, &rootnode.subsys_list); |
cf5d5941 BB |
1052 | /* subsystem is now free - drop reference on module */ |
1053 | module_put(ss->module); | |
a1a71b45 | 1054 | } else if (bit & final_subsys_mask) { |
ddbcc7e8 | 1055 | /* Subsystem state should already exist */ |
aae8aab4 | 1056 | BUG_ON(ss == NULL); |
bd89aabc | 1057 | BUG_ON(!cgrp->subsys[i]); |
cf5d5941 BB |
1058 | /* |
1059 | * a refcount was taken, but we already had one, so | |
1060 | * drop the extra reference. | |
1061 | */ | |
1062 | module_put(ss->module); | |
1063 | #ifdef CONFIG_MODULE_UNLOAD | |
1064 | BUG_ON(ss->module && !module_refcount(ss->module)); | |
1065 | #endif | |
ddbcc7e8 PM |
1066 | } else { |
1067 | /* Subsystem state shouldn't exist */ | |
bd89aabc | 1068 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1069 | } |
1070 | } | |
a1a71b45 | 1071 | root->subsys_mask = root->actual_subsys_mask = final_subsys_mask; |
ddbcc7e8 PM |
1072 | |
1073 | return 0; | |
1074 | } | |
1075 | ||
34c80b1d | 1076 | static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) |
ddbcc7e8 | 1077 | { |
34c80b1d | 1078 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
ddbcc7e8 PM |
1079 | struct cgroup_subsys *ss; |
1080 | ||
e25e2cbb | 1081 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1082 | for_each_subsys(root, ss) |
1083 | seq_printf(seq, ",%s", ss->name); | |
873fe09e TH |
1084 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) |
1085 | seq_puts(seq, ",sane_behavior"); | |
93438629 | 1086 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1087 | seq_puts(seq, ",noprefix"); |
93438629 | 1088 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1089 | seq_puts(seq, ",xattr"); |
81a6a5cd PM |
1090 | if (strlen(root->release_agent_path)) |
1091 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
2260e7fc | 1092 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags)) |
97978e6d | 1093 | seq_puts(seq, ",clone_children"); |
c6d57f33 PM |
1094 | if (strlen(root->name)) |
1095 | seq_printf(seq, ",name=%s", root->name); | |
e25e2cbb | 1096 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1097 | return 0; |
1098 | } | |
1099 | ||
1100 | struct cgroup_sb_opts { | |
a1a71b45 | 1101 | unsigned long subsys_mask; |
ddbcc7e8 | 1102 | unsigned long flags; |
81a6a5cd | 1103 | char *release_agent; |
2260e7fc | 1104 | bool cpuset_clone_children; |
c6d57f33 | 1105 | char *name; |
2c6ab6d2 PM |
1106 | /* User explicitly requested empty subsystem */ |
1107 | bool none; | |
c6d57f33 PM |
1108 | |
1109 | struct cgroupfs_root *new_root; | |
2c6ab6d2 | 1110 | |
ddbcc7e8 PM |
1111 | }; |
1112 | ||
aae8aab4 BB |
1113 | /* |
1114 | * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call | |
cf5d5941 BB |
1115 | * with cgroup_mutex held to protect the subsys[] array. This function takes |
1116 | * refcounts on subsystems to be used, unless it returns error, in which case | |
1117 | * no refcounts are taken. | |
aae8aab4 | 1118 | */ |
cf5d5941 | 1119 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1120 | { |
32a8cf23 DL |
1121 | char *token, *o = data; |
1122 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1123 | unsigned long mask = (unsigned long)-1; |
cf5d5941 BB |
1124 | int i; |
1125 | bool module_pin_failed = false; | |
f9ab5b5b | 1126 | |
aae8aab4 BB |
1127 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1128 | ||
f9ab5b5b LZ |
1129 | #ifdef CONFIG_CPUSETS |
1130 | mask = ~(1UL << cpuset_subsys_id); | |
1131 | #endif | |
ddbcc7e8 | 1132 | |
c6d57f33 | 1133 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1134 | |
1135 | while ((token = strsep(&o, ",")) != NULL) { | |
1136 | if (!*token) | |
1137 | return -EINVAL; | |
32a8cf23 | 1138 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1139 | /* Explicitly have no subsystems */ |
1140 | opts->none = true; | |
32a8cf23 DL |
1141 | continue; |
1142 | } | |
1143 | if (!strcmp(token, "all")) { | |
1144 | /* Mutually exclusive option 'all' + subsystem name */ | |
1145 | if (one_ss) | |
1146 | return -EINVAL; | |
1147 | all_ss = true; | |
1148 | continue; | |
1149 | } | |
873fe09e TH |
1150 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1151 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1152 | continue; | |
1153 | } | |
32a8cf23 | 1154 | if (!strcmp(token, "noprefix")) { |
93438629 | 1155 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1156 | continue; |
1157 | } | |
1158 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1159 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1160 | continue; |
1161 | } | |
03b1cde6 | 1162 | if (!strcmp(token, "xattr")) { |
93438629 | 1163 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1164 | continue; |
1165 | } | |
32a8cf23 | 1166 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1167 | /* Specifying two release agents is forbidden */ |
1168 | if (opts->release_agent) | |
1169 | return -EINVAL; | |
c6d57f33 | 1170 | opts->release_agent = |
e400c285 | 1171 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1172 | if (!opts->release_agent) |
1173 | return -ENOMEM; | |
32a8cf23 DL |
1174 | continue; |
1175 | } | |
1176 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1177 | const char *name = token + 5; |
1178 | /* Can't specify an empty name */ | |
1179 | if (!strlen(name)) | |
1180 | return -EINVAL; | |
1181 | /* Must match [\w.-]+ */ | |
1182 | for (i = 0; i < strlen(name); i++) { | |
1183 | char c = name[i]; | |
1184 | if (isalnum(c)) | |
1185 | continue; | |
1186 | if ((c == '.') || (c == '-') || (c == '_')) | |
1187 | continue; | |
1188 | return -EINVAL; | |
1189 | } | |
1190 | /* Specifying two names is forbidden */ | |
1191 | if (opts->name) | |
1192 | return -EINVAL; | |
1193 | opts->name = kstrndup(name, | |
e400c285 | 1194 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1195 | GFP_KERNEL); |
1196 | if (!opts->name) | |
1197 | return -ENOMEM; | |
32a8cf23 DL |
1198 | |
1199 | continue; | |
1200 | } | |
1201 | ||
1202 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1203 | struct cgroup_subsys *ss = subsys[i]; | |
1204 | if (ss == NULL) | |
1205 | continue; | |
1206 | if (strcmp(token, ss->name)) | |
1207 | continue; | |
1208 | if (ss->disabled) | |
1209 | continue; | |
1210 | ||
1211 | /* Mutually exclusive option 'all' + subsystem name */ | |
1212 | if (all_ss) | |
1213 | return -EINVAL; | |
a1a71b45 | 1214 | set_bit(i, &opts->subsys_mask); |
32a8cf23 DL |
1215 | one_ss = true; |
1216 | ||
1217 | break; | |
1218 | } | |
1219 | if (i == CGROUP_SUBSYS_COUNT) | |
1220 | return -ENOENT; | |
1221 | } | |
1222 | ||
1223 | /* | |
1224 | * If the 'all' option was specified select all the subsystems, | |
0d19ea86 LZ |
1225 | * otherwise if 'none', 'name=' and a subsystem name options |
1226 | * were not specified, let's default to 'all' | |
32a8cf23 | 1227 | */ |
0d19ea86 | 1228 | if (all_ss || (!one_ss && !opts->none && !opts->name)) { |
32a8cf23 DL |
1229 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
1230 | struct cgroup_subsys *ss = subsys[i]; | |
1231 | if (ss == NULL) | |
1232 | continue; | |
1233 | if (ss->disabled) | |
1234 | continue; | |
a1a71b45 | 1235 | set_bit(i, &opts->subsys_mask); |
ddbcc7e8 PM |
1236 | } |
1237 | } | |
1238 | ||
2c6ab6d2 PM |
1239 | /* Consistency checks */ |
1240 | ||
873fe09e TH |
1241 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1242 | pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); | |
1243 | ||
1244 | if (opts->flags & CGRP_ROOT_NOPREFIX) { | |
1245 | pr_err("cgroup: sane_behavior: noprefix is not allowed\n"); | |
1246 | return -EINVAL; | |
1247 | } | |
1248 | ||
1249 | if (opts->cpuset_clone_children) { | |
1250 | pr_err("cgroup: sane_behavior: clone_children is not allowed\n"); | |
1251 | return -EINVAL; | |
1252 | } | |
1253 | } | |
1254 | ||
f9ab5b5b LZ |
1255 | /* |
1256 | * Option noprefix was introduced just for backward compatibility | |
1257 | * with the old cpuset, so we allow noprefix only if mounting just | |
1258 | * the cpuset subsystem. | |
1259 | */ | |
93438629 | 1260 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1261 | return -EINVAL; |
1262 | ||
2c6ab6d2 PM |
1263 | |
1264 | /* Can't specify "none" and some subsystems */ | |
a1a71b45 | 1265 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1266 | return -EINVAL; |
1267 | ||
1268 | /* | |
1269 | * We either have to specify by name or by subsystems. (So all | |
1270 | * empty hierarchies must have a name). | |
1271 | */ | |
a1a71b45 | 1272 | if (!opts->subsys_mask && !opts->name) |
ddbcc7e8 PM |
1273 | return -EINVAL; |
1274 | ||
cf5d5941 BB |
1275 | /* |
1276 | * Grab references on all the modules we'll need, so the subsystems | |
1277 | * don't dance around before rebind_subsystems attaches them. This may | |
1278 | * take duplicate reference counts on a subsystem that's already used, | |
1279 | * but rebind_subsystems handles this case. | |
1280 | */ | |
be45c900 | 1281 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
cf5d5941 BB |
1282 | unsigned long bit = 1UL << i; |
1283 | ||
a1a71b45 | 1284 | if (!(bit & opts->subsys_mask)) |
cf5d5941 BB |
1285 | continue; |
1286 | if (!try_module_get(subsys[i]->module)) { | |
1287 | module_pin_failed = true; | |
1288 | break; | |
1289 | } | |
1290 | } | |
1291 | if (module_pin_failed) { | |
1292 | /* | |
1293 | * oops, one of the modules was going away. this means that we | |
1294 | * raced with a module_delete call, and to the user this is | |
1295 | * essentially a "subsystem doesn't exist" case. | |
1296 | */ | |
be45c900 | 1297 | for (i--; i >= 0; i--) { |
cf5d5941 BB |
1298 | /* drop refcounts only on the ones we took */ |
1299 | unsigned long bit = 1UL << i; | |
1300 | ||
a1a71b45 | 1301 | if (!(bit & opts->subsys_mask)) |
cf5d5941 BB |
1302 | continue; |
1303 | module_put(subsys[i]->module); | |
1304 | } | |
1305 | return -ENOENT; | |
1306 | } | |
1307 | ||
ddbcc7e8 PM |
1308 | return 0; |
1309 | } | |
1310 | ||
a1a71b45 | 1311 | static void drop_parsed_module_refcounts(unsigned long subsys_mask) |
cf5d5941 BB |
1312 | { |
1313 | int i; | |
be45c900 | 1314 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
cf5d5941 BB |
1315 | unsigned long bit = 1UL << i; |
1316 | ||
a1a71b45 | 1317 | if (!(bit & subsys_mask)) |
cf5d5941 BB |
1318 | continue; |
1319 | module_put(subsys[i]->module); | |
1320 | } | |
1321 | } | |
1322 | ||
ddbcc7e8 PM |
1323 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) |
1324 | { | |
1325 | int ret = 0; | |
1326 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1327 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1328 | struct cgroup_sb_opts opts; |
a1a71b45 | 1329 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1330 | |
873fe09e TH |
1331 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1332 | pr_err("cgroup: sane_behavior: remount is not allowed\n"); | |
1333 | return -EINVAL; | |
1334 | } | |
1335 | ||
bd89aabc | 1336 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 | 1337 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1338 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1339 | |
1340 | /* See what subsystems are wanted */ | |
1341 | ret = parse_cgroupfs_options(data, &opts); | |
1342 | if (ret) | |
1343 | goto out_unlock; | |
1344 | ||
a1a71b45 | 1345 | if (opts.subsys_mask != root->actual_subsys_mask || opts.release_agent) |
8b5a5a9d TH |
1346 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", |
1347 | task_tgid_nr(current), current->comm); | |
1348 | ||
a1a71b45 AR |
1349 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1350 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1351 | |
cf5d5941 BB |
1352 | /* Don't allow flags or name to change at remount */ |
1353 | if (opts.flags != root->flags || | |
1354 | (opts.name && strcmp(opts.name, root->name))) { | |
c6d57f33 | 1355 | ret = -EINVAL; |
a1a71b45 | 1356 | drop_parsed_module_refcounts(opts.subsys_mask); |
c6d57f33 PM |
1357 | goto out_unlock; |
1358 | } | |
1359 | ||
7083d037 G |
1360 | /* |
1361 | * Clear out the files of subsystems that should be removed, do | |
1362 | * this before rebind_subsystems, since rebind_subsystems may | |
1363 | * change this hierarchy's subsys_list. | |
1364 | */ | |
1365 | cgroup_clear_directory(cgrp->dentry, false, removed_mask); | |
1366 | ||
a1a71b45 | 1367 | ret = rebind_subsystems(root, opts.subsys_mask); |
cf5d5941 | 1368 | if (ret) { |
7083d037 G |
1369 | /* rebind_subsystems failed, re-populate the removed files */ |
1370 | cgroup_populate_dir(cgrp, false, removed_mask); | |
a1a71b45 | 1371 | drop_parsed_module_refcounts(opts.subsys_mask); |
0670e08b | 1372 | goto out_unlock; |
cf5d5941 | 1373 | } |
ddbcc7e8 | 1374 | |
13af07df | 1375 | /* re-populate subsystem files */ |
a1a71b45 | 1376 | cgroup_populate_dir(cgrp, false, added_mask); |
ddbcc7e8 | 1377 | |
81a6a5cd PM |
1378 | if (opts.release_agent) |
1379 | strcpy(root->release_agent_path, opts.release_agent); | |
ddbcc7e8 | 1380 | out_unlock: |
66bdc9cf | 1381 | kfree(opts.release_agent); |
c6d57f33 | 1382 | kfree(opts.name); |
e25e2cbb | 1383 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1384 | mutex_unlock(&cgroup_mutex); |
bd89aabc | 1385 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
1386 | return ret; |
1387 | } | |
1388 | ||
b87221de | 1389 | static const struct super_operations cgroup_ops = { |
ddbcc7e8 PM |
1390 | .statfs = simple_statfs, |
1391 | .drop_inode = generic_delete_inode, | |
1392 | .show_options = cgroup_show_options, | |
1393 | .remount_fs = cgroup_remount, | |
1394 | }; | |
1395 | ||
cc31edce PM |
1396 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1397 | { | |
1398 | INIT_LIST_HEAD(&cgrp->sibling); | |
1399 | INIT_LIST_HEAD(&cgrp->children); | |
05ef1d7c | 1400 | INIT_LIST_HEAD(&cgrp->files); |
69d0206c | 1401 | INIT_LIST_HEAD(&cgrp->cset_links); |
cc31edce | 1402 | INIT_LIST_HEAD(&cgrp->release_list); |
72a8cb30 BB |
1403 | INIT_LIST_HEAD(&cgrp->pidlists); |
1404 | mutex_init(&cgrp->pidlist_mutex); | |
0dea1168 KS |
1405 | INIT_LIST_HEAD(&cgrp->event_list); |
1406 | spin_lock_init(&cgrp->event_list_lock); | |
03b1cde6 | 1407 | simple_xattrs_init(&cgrp->xattrs); |
cc31edce | 1408 | } |
c6d57f33 | 1409 | |
ddbcc7e8 PM |
1410 | static void init_cgroup_root(struct cgroupfs_root *root) |
1411 | { | |
bd89aabc | 1412 | struct cgroup *cgrp = &root->top_cgroup; |
b0ca5a84 | 1413 | |
ddbcc7e8 PM |
1414 | INIT_LIST_HEAD(&root->subsys_list); |
1415 | INIT_LIST_HEAD(&root->root_list); | |
1416 | root->number_of_cgroups = 1; | |
bd89aabc | 1417 | cgrp->root = root; |
65dff759 | 1418 | cgrp->name = &root_cgroup_name; |
cc31edce | 1419 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 PM |
1420 | } |
1421 | ||
fa3ca07e | 1422 | static int cgroup_init_root_id(struct cgroupfs_root *root) |
2c6ab6d2 | 1423 | { |
1a574231 | 1424 | int id; |
2c6ab6d2 | 1425 | |
54e7b4eb TH |
1426 | lockdep_assert_held(&cgroup_mutex); |
1427 | lockdep_assert_held(&cgroup_root_mutex); | |
1428 | ||
1a574231 TH |
1429 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 2, 0, GFP_KERNEL); |
1430 | if (id < 0) | |
1431 | return id; | |
1432 | ||
1433 | root->hierarchy_id = id; | |
fa3ca07e TH |
1434 | return 0; |
1435 | } | |
1436 | ||
1437 | static void cgroup_exit_root_id(struct cgroupfs_root *root) | |
1438 | { | |
54e7b4eb TH |
1439 | lockdep_assert_held(&cgroup_mutex); |
1440 | lockdep_assert_held(&cgroup_root_mutex); | |
1441 | ||
fa3ca07e | 1442 | if (root->hierarchy_id) { |
1a574231 | 1443 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); |
fa3ca07e TH |
1444 | root->hierarchy_id = 0; |
1445 | } | |
2c6ab6d2 PM |
1446 | } |
1447 | ||
ddbcc7e8 PM |
1448 | static int cgroup_test_super(struct super_block *sb, void *data) |
1449 | { | |
c6d57f33 | 1450 | struct cgroup_sb_opts *opts = data; |
ddbcc7e8 PM |
1451 | struct cgroupfs_root *root = sb->s_fs_info; |
1452 | ||
c6d57f33 PM |
1453 | /* If we asked for a name then it must match */ |
1454 | if (opts->name && strcmp(opts->name, root->name)) | |
1455 | return 0; | |
ddbcc7e8 | 1456 | |
2c6ab6d2 PM |
1457 | /* |
1458 | * If we asked for subsystems (or explicitly for no | |
1459 | * subsystems) then they must match | |
1460 | */ | |
a1a71b45 AR |
1461 | if ((opts->subsys_mask || opts->none) |
1462 | && (opts->subsys_mask != root->subsys_mask)) | |
ddbcc7e8 PM |
1463 | return 0; |
1464 | ||
1465 | return 1; | |
1466 | } | |
1467 | ||
c6d57f33 PM |
1468 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1469 | { | |
1470 | struct cgroupfs_root *root; | |
1471 | ||
a1a71b45 | 1472 | if (!opts->subsys_mask && !opts->none) |
c6d57f33 PM |
1473 | return NULL; |
1474 | ||
1475 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1476 | if (!root) | |
1477 | return ERR_PTR(-ENOMEM); | |
1478 | ||
1479 | init_cgroup_root(root); | |
2c6ab6d2 | 1480 | |
a1a71b45 | 1481 | root->subsys_mask = opts->subsys_mask; |
c6d57f33 | 1482 | root->flags = opts->flags; |
0a950f65 | 1483 | ida_init(&root->cgroup_ida); |
c6d57f33 PM |
1484 | if (opts->release_agent) |
1485 | strcpy(root->release_agent_path, opts->release_agent); | |
1486 | if (opts->name) | |
1487 | strcpy(root->name, opts->name); | |
2260e7fc TH |
1488 | if (opts->cpuset_clone_children) |
1489 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags); | |
c6d57f33 PM |
1490 | return root; |
1491 | } | |
1492 | ||
fa3ca07e | 1493 | static void cgroup_free_root(struct cgroupfs_root *root) |
2c6ab6d2 | 1494 | { |
fa3ca07e TH |
1495 | if (root) { |
1496 | /* hierarhcy ID shoulid already have been released */ | |
1497 | WARN_ON_ONCE(root->hierarchy_id); | |
2c6ab6d2 | 1498 | |
fa3ca07e TH |
1499 | ida_destroy(&root->cgroup_ida); |
1500 | kfree(root); | |
1501 | } | |
2c6ab6d2 PM |
1502 | } |
1503 | ||
ddbcc7e8 PM |
1504 | static int cgroup_set_super(struct super_block *sb, void *data) |
1505 | { | |
1506 | int ret; | |
c6d57f33 PM |
1507 | struct cgroup_sb_opts *opts = data; |
1508 | ||
1509 | /* If we don't have a new root, we can't set up a new sb */ | |
1510 | if (!opts->new_root) | |
1511 | return -EINVAL; | |
1512 | ||
a1a71b45 | 1513 | BUG_ON(!opts->subsys_mask && !opts->none); |
ddbcc7e8 PM |
1514 | |
1515 | ret = set_anon_super(sb, NULL); | |
1516 | if (ret) | |
1517 | return ret; | |
1518 | ||
c6d57f33 PM |
1519 | sb->s_fs_info = opts->new_root; |
1520 | opts->new_root->sb = sb; | |
ddbcc7e8 PM |
1521 | |
1522 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
1523 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
1524 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
1525 | sb->s_op = &cgroup_ops; | |
1526 | ||
1527 | return 0; | |
1528 | } | |
1529 | ||
1530 | static int cgroup_get_rootdir(struct super_block *sb) | |
1531 | { | |
0df6a63f AV |
1532 | static const struct dentry_operations cgroup_dops = { |
1533 | .d_iput = cgroup_diput, | |
c72a04e3 | 1534 | .d_delete = cgroup_delete, |
0df6a63f AV |
1535 | }; |
1536 | ||
ddbcc7e8 PM |
1537 | struct inode *inode = |
1538 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
ddbcc7e8 PM |
1539 | |
1540 | if (!inode) | |
1541 | return -ENOMEM; | |
1542 | ||
ddbcc7e8 PM |
1543 | inode->i_fop = &simple_dir_operations; |
1544 | inode->i_op = &cgroup_dir_inode_operations; | |
1545 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1546 | inc_nlink(inode); | |
48fde701 AV |
1547 | sb->s_root = d_make_root(inode); |
1548 | if (!sb->s_root) | |
ddbcc7e8 | 1549 | return -ENOMEM; |
0df6a63f AV |
1550 | /* for everything else we want ->d_op set */ |
1551 | sb->s_d_op = &cgroup_dops; | |
ddbcc7e8 PM |
1552 | return 0; |
1553 | } | |
1554 | ||
f7e83571 | 1555 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1556 | int flags, const char *unused_dev_name, |
f7e83571 | 1557 | void *data) |
ddbcc7e8 PM |
1558 | { |
1559 | struct cgroup_sb_opts opts; | |
c6d57f33 | 1560 | struct cgroupfs_root *root; |
ddbcc7e8 PM |
1561 | int ret = 0; |
1562 | struct super_block *sb; | |
c6d57f33 | 1563 | struct cgroupfs_root *new_root; |
e25e2cbb | 1564 | struct inode *inode; |
ddbcc7e8 PM |
1565 | |
1566 | /* First find the desired set of subsystems */ | |
aae8aab4 | 1567 | mutex_lock(&cgroup_mutex); |
ddbcc7e8 | 1568 | ret = parse_cgroupfs_options(data, &opts); |
aae8aab4 | 1569 | mutex_unlock(&cgroup_mutex); |
c6d57f33 PM |
1570 | if (ret) |
1571 | goto out_err; | |
ddbcc7e8 | 1572 | |
c6d57f33 PM |
1573 | /* |
1574 | * Allocate a new cgroup root. We may not need it if we're | |
1575 | * reusing an existing hierarchy. | |
1576 | */ | |
1577 | new_root = cgroup_root_from_opts(&opts); | |
1578 | if (IS_ERR(new_root)) { | |
1579 | ret = PTR_ERR(new_root); | |
cf5d5941 | 1580 | goto drop_modules; |
81a6a5cd | 1581 | } |
c6d57f33 | 1582 | opts.new_root = new_root; |
ddbcc7e8 | 1583 | |
c6d57f33 | 1584 | /* Locate an existing or new sb for this hierarchy */ |
9249e17f | 1585 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts); |
ddbcc7e8 | 1586 | if (IS_ERR(sb)) { |
c6d57f33 | 1587 | ret = PTR_ERR(sb); |
fa3ca07e | 1588 | cgroup_free_root(opts.new_root); |
cf5d5941 | 1589 | goto drop_modules; |
ddbcc7e8 PM |
1590 | } |
1591 | ||
c6d57f33 PM |
1592 | root = sb->s_fs_info; |
1593 | BUG_ON(!root); | |
1594 | if (root == opts.new_root) { | |
1595 | /* We used the new root structure, so this is a new hierarchy */ | |
69d0206c | 1596 | struct list_head tmp_links; |
c12f65d4 | 1597 | struct cgroup *root_cgrp = &root->top_cgroup; |
c6d57f33 | 1598 | struct cgroupfs_root *existing_root; |
2ce9738b | 1599 | const struct cred *cred; |
28fd5dfc | 1600 | int i; |
5abb8855 | 1601 | struct css_set *cset; |
ddbcc7e8 PM |
1602 | |
1603 | BUG_ON(sb->s_root != NULL); | |
1604 | ||
1605 | ret = cgroup_get_rootdir(sb); | |
1606 | if (ret) | |
1607 | goto drop_new_super; | |
817929ec | 1608 | inode = sb->s_root->d_inode; |
ddbcc7e8 | 1609 | |
817929ec | 1610 | mutex_lock(&inode->i_mutex); |
ddbcc7e8 | 1611 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1612 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 | 1613 | |
e25e2cbb TH |
1614 | /* Check for name clashes with existing mounts */ |
1615 | ret = -EBUSY; | |
1616 | if (strlen(root->name)) | |
1617 | for_each_active_root(existing_root) | |
1618 | if (!strcmp(existing_root->name, root->name)) | |
1619 | goto unlock_drop; | |
c6d57f33 | 1620 | |
817929ec PM |
1621 | /* |
1622 | * We're accessing css_set_count without locking | |
1623 | * css_set_lock here, but that's OK - it can only be | |
1624 | * increased by someone holding cgroup_lock, and | |
1625 | * that's us. The worst that can happen is that we | |
1626 | * have some link structures left over | |
1627 | */ | |
69d0206c | 1628 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); |
e25e2cbb TH |
1629 | if (ret) |
1630 | goto unlock_drop; | |
817929ec | 1631 | |
fa3ca07e TH |
1632 | ret = cgroup_init_root_id(root); |
1633 | if (ret) | |
1634 | goto unlock_drop; | |
1635 | ||
a1a71b45 | 1636 | ret = rebind_subsystems(root, root->subsys_mask); |
ddbcc7e8 | 1637 | if (ret == -EBUSY) { |
69d0206c | 1638 | free_cgrp_cset_links(&tmp_links); |
e25e2cbb | 1639 | goto unlock_drop; |
ddbcc7e8 | 1640 | } |
cf5d5941 BB |
1641 | /* |
1642 | * There must be no failure case after here, since rebinding | |
1643 | * takes care of subsystems' refcounts, which are explicitly | |
1644 | * dropped in the failure exit path. | |
1645 | */ | |
ddbcc7e8 PM |
1646 | |
1647 | /* EBUSY should be the only error here */ | |
1648 | BUG_ON(ret); | |
1649 | ||
1650 | list_add(&root->root_list, &roots); | |
817929ec | 1651 | root_count++; |
ddbcc7e8 | 1652 | |
c12f65d4 | 1653 | sb->s_root->d_fsdata = root_cgrp; |
ddbcc7e8 PM |
1654 | root->top_cgroup.dentry = sb->s_root; |
1655 | ||
817929ec PM |
1656 | /* Link the top cgroup in this hierarchy into all |
1657 | * the css_set objects */ | |
1658 | write_lock(&css_set_lock); | |
5abb8855 | 1659 | hash_for_each(css_set_table, i, cset, hlist) |
69d0206c | 1660 | link_css_set(&tmp_links, cset, root_cgrp); |
817929ec PM |
1661 | write_unlock(&css_set_lock); |
1662 | ||
69d0206c | 1663 | free_cgrp_cset_links(&tmp_links); |
817929ec | 1664 | |
c12f65d4 | 1665 | BUG_ON(!list_empty(&root_cgrp->children)); |
ddbcc7e8 PM |
1666 | BUG_ON(root->number_of_cgroups != 1); |
1667 | ||
2ce9738b | 1668 | cred = override_creds(&init_cred); |
a1a71b45 | 1669 | cgroup_populate_dir(root_cgrp, true, root->subsys_mask); |
2ce9738b | 1670 | revert_creds(cred); |
e25e2cbb | 1671 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1672 | mutex_unlock(&cgroup_mutex); |
34f77a90 | 1673 | mutex_unlock(&inode->i_mutex); |
c6d57f33 PM |
1674 | } else { |
1675 | /* | |
1676 | * We re-used an existing hierarchy - the new root (if | |
1677 | * any) is not needed | |
1678 | */ | |
fa3ca07e | 1679 | cgroup_free_root(opts.new_root); |
873fe09e | 1680 | |
2a0ff3fb JL |
1681 | if (root->flags != opts.flags) { |
1682 | if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { | |
1683 | pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); | |
1684 | ret = -EINVAL; | |
1685 | goto drop_new_super; | |
1686 | } else { | |
1687 | pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); | |
1688 | } | |
873fe09e TH |
1689 | } |
1690 | ||
cf5d5941 | 1691 | /* no subsys rebinding, so refcounts don't change */ |
a1a71b45 | 1692 | drop_parsed_module_refcounts(opts.subsys_mask); |
ddbcc7e8 PM |
1693 | } |
1694 | ||
c6d57f33 PM |
1695 | kfree(opts.release_agent); |
1696 | kfree(opts.name); | |
f7e83571 | 1697 | return dget(sb->s_root); |
ddbcc7e8 | 1698 | |
e25e2cbb | 1699 | unlock_drop: |
fa3ca07e | 1700 | cgroup_exit_root_id(root); |
e25e2cbb TH |
1701 | mutex_unlock(&cgroup_root_mutex); |
1702 | mutex_unlock(&cgroup_mutex); | |
1703 | mutex_unlock(&inode->i_mutex); | |
ddbcc7e8 | 1704 | drop_new_super: |
6f5bbff9 | 1705 | deactivate_locked_super(sb); |
cf5d5941 | 1706 | drop_modules: |
a1a71b45 | 1707 | drop_parsed_module_refcounts(opts.subsys_mask); |
c6d57f33 PM |
1708 | out_err: |
1709 | kfree(opts.release_agent); | |
1710 | kfree(opts.name); | |
f7e83571 | 1711 | return ERR_PTR(ret); |
ddbcc7e8 PM |
1712 | } |
1713 | ||
1714 | static void cgroup_kill_sb(struct super_block *sb) { | |
1715 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1716 | struct cgroup *cgrp = &root->top_cgroup; |
69d0206c | 1717 | struct cgrp_cset_link *link, *tmp_link; |
ddbcc7e8 PM |
1718 | int ret; |
1719 | ||
1720 | BUG_ON(!root); | |
1721 | ||
1722 | BUG_ON(root->number_of_cgroups != 1); | |
bd89aabc | 1723 | BUG_ON(!list_empty(&cgrp->children)); |
ddbcc7e8 PM |
1724 | |
1725 | mutex_lock(&cgroup_mutex); | |
e25e2cbb | 1726 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1727 | |
1728 | /* Rebind all subsystems back to the default hierarchy */ | |
1729 | ret = rebind_subsystems(root, 0); | |
1730 | /* Shouldn't be able to fail ... */ | |
1731 | BUG_ON(ret); | |
1732 | ||
817929ec | 1733 | /* |
69d0206c | 1734 | * Release all the links from cset_links to this hierarchy's |
817929ec PM |
1735 | * root cgroup |
1736 | */ | |
1737 | write_lock(&css_set_lock); | |
71cbb949 | 1738 | |
69d0206c TH |
1739 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { |
1740 | list_del(&link->cset_link); | |
1741 | list_del(&link->cgrp_link); | |
817929ec PM |
1742 | kfree(link); |
1743 | } | |
1744 | write_unlock(&css_set_lock); | |
1745 | ||
839ec545 PM |
1746 | if (!list_empty(&root->root_list)) { |
1747 | list_del(&root->root_list); | |
1748 | root_count--; | |
1749 | } | |
e5f6a860 | 1750 | |
fa3ca07e TH |
1751 | cgroup_exit_root_id(root); |
1752 | ||
e25e2cbb | 1753 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1754 | mutex_unlock(&cgroup_mutex); |
1755 | ||
03b1cde6 AR |
1756 | simple_xattrs_free(&cgrp->xattrs); |
1757 | ||
ddbcc7e8 | 1758 | kill_litter_super(sb); |
fa3ca07e | 1759 | cgroup_free_root(root); |
ddbcc7e8 PM |
1760 | } |
1761 | ||
1762 | static struct file_system_type cgroup_fs_type = { | |
1763 | .name = "cgroup", | |
f7e83571 | 1764 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1765 | .kill_sb = cgroup_kill_sb, |
1766 | }; | |
1767 | ||
676db4af GK |
1768 | static struct kobject *cgroup_kobj; |
1769 | ||
a043e3b2 LZ |
1770 | /** |
1771 | * cgroup_path - generate the path of a cgroup | |
1772 | * @cgrp: the cgroup in question | |
1773 | * @buf: the buffer to write the path into | |
1774 | * @buflen: the length of the buffer | |
1775 | * | |
65dff759 LZ |
1776 | * Writes path of cgroup into buf. Returns 0 on success, -errno on error. |
1777 | * | |
1778 | * We can't generate cgroup path using dentry->d_name, as accessing | |
1779 | * dentry->name must be protected by irq-unsafe dentry->d_lock or parent | |
1780 | * inode's i_mutex, while on the other hand cgroup_path() can be called | |
1781 | * with some irq-safe spinlocks held. | |
ddbcc7e8 | 1782 | */ |
bd89aabc | 1783 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
ddbcc7e8 | 1784 | { |
65dff759 | 1785 | int ret = -ENAMETOOLONG; |
ddbcc7e8 | 1786 | char *start; |
febfcef6 | 1787 | |
da1f296f TH |
1788 | if (!cgrp->parent) { |
1789 | if (strlcpy(buf, "/", buflen) >= buflen) | |
1790 | return -ENAMETOOLONG; | |
ddbcc7e8 PM |
1791 | return 0; |
1792 | } | |
1793 | ||
316eb661 | 1794 | start = buf + buflen - 1; |
316eb661 | 1795 | *start = '\0'; |
9a9686b6 | 1796 | |
65dff759 | 1797 | rcu_read_lock(); |
da1f296f | 1798 | do { |
65dff759 LZ |
1799 | const char *name = cgroup_name(cgrp); |
1800 | int len; | |
1801 | ||
1802 | len = strlen(name); | |
ddbcc7e8 | 1803 | if ((start -= len) < buf) |
65dff759 LZ |
1804 | goto out; |
1805 | memcpy(start, name, len); | |
9a9686b6 | 1806 | |
ddbcc7e8 | 1807 | if (--start < buf) |
65dff759 | 1808 | goto out; |
ddbcc7e8 | 1809 | *start = '/'; |
65dff759 LZ |
1810 | |
1811 | cgrp = cgrp->parent; | |
da1f296f | 1812 | } while (cgrp->parent); |
65dff759 | 1813 | ret = 0; |
ddbcc7e8 | 1814 | memmove(buf, start, buf + buflen - start); |
65dff759 LZ |
1815 | out: |
1816 | rcu_read_unlock(); | |
1817 | return ret; | |
ddbcc7e8 | 1818 | } |
67523c48 | 1819 | EXPORT_SYMBOL_GPL(cgroup_path); |
ddbcc7e8 | 1820 | |
857a2beb TH |
1821 | /** |
1822 | * task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy | |
1823 | * @task: target task | |
1824 | * @hierarchy_id: the hierarchy to look up @task's cgroup from | |
1825 | * @buf: the buffer to write the path into | |
1826 | * @buflen: the length of the buffer | |
1827 | * | |
1828 | * Determine @task's cgroup on the hierarchy specified by @hierarchy_id and | |
1829 | * copy its path into @buf. This function grabs cgroup_mutex and shouldn't | |
1830 | * be used inside locks used by cgroup controller callbacks. | |
1831 | */ | |
1832 | int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id, | |
1833 | char *buf, size_t buflen) | |
1834 | { | |
1835 | struct cgroupfs_root *root; | |
1836 | struct cgroup *cgrp = NULL; | |
1837 | int ret = -ENOENT; | |
1838 | ||
1839 | mutex_lock(&cgroup_mutex); | |
1840 | ||
1841 | root = idr_find(&cgroup_hierarchy_idr, hierarchy_id); | |
1842 | if (root) { | |
1843 | cgrp = task_cgroup_from_root(task, root); | |
1844 | ret = cgroup_path(cgrp, buf, buflen); | |
1845 | } | |
1846 | ||
1847 | mutex_unlock(&cgroup_mutex); | |
1848 | ||
1849 | return ret; | |
1850 | } | |
1851 | EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy); | |
1852 | ||
2f7ee569 TH |
1853 | /* |
1854 | * Control Group taskset | |
1855 | */ | |
134d3373 TH |
1856 | struct task_and_cgroup { |
1857 | struct task_struct *task; | |
1858 | struct cgroup *cgrp; | |
61d1d219 | 1859 | struct css_set *cg; |
134d3373 TH |
1860 | }; |
1861 | ||
2f7ee569 TH |
1862 | struct cgroup_taskset { |
1863 | struct task_and_cgroup single; | |
1864 | struct flex_array *tc_array; | |
1865 | int tc_array_len; | |
1866 | int idx; | |
1867 | struct cgroup *cur_cgrp; | |
1868 | }; | |
1869 | ||
1870 | /** | |
1871 | * cgroup_taskset_first - reset taskset and return the first task | |
1872 | * @tset: taskset of interest | |
1873 | * | |
1874 | * @tset iteration is initialized and the first task is returned. | |
1875 | */ | |
1876 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1877 | { | |
1878 | if (tset->tc_array) { | |
1879 | tset->idx = 0; | |
1880 | return cgroup_taskset_next(tset); | |
1881 | } else { | |
1882 | tset->cur_cgrp = tset->single.cgrp; | |
1883 | return tset->single.task; | |
1884 | } | |
1885 | } | |
1886 | EXPORT_SYMBOL_GPL(cgroup_taskset_first); | |
1887 | ||
1888 | /** | |
1889 | * cgroup_taskset_next - iterate to the next task in taskset | |
1890 | * @tset: taskset of interest | |
1891 | * | |
1892 | * Return the next task in @tset. Iteration must have been initialized | |
1893 | * with cgroup_taskset_first(). | |
1894 | */ | |
1895 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1896 | { | |
1897 | struct task_and_cgroup *tc; | |
1898 | ||
1899 | if (!tset->tc_array || tset->idx >= tset->tc_array_len) | |
1900 | return NULL; | |
1901 | ||
1902 | tc = flex_array_get(tset->tc_array, tset->idx++); | |
1903 | tset->cur_cgrp = tc->cgrp; | |
1904 | return tc->task; | |
1905 | } | |
1906 | EXPORT_SYMBOL_GPL(cgroup_taskset_next); | |
1907 | ||
1908 | /** | |
1909 | * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task | |
1910 | * @tset: taskset of interest | |
1911 | * | |
1912 | * Return the cgroup for the current (last returned) task of @tset. This | |
1913 | * function must be preceded by either cgroup_taskset_first() or | |
1914 | * cgroup_taskset_next(). | |
1915 | */ | |
1916 | struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) | |
1917 | { | |
1918 | return tset->cur_cgrp; | |
1919 | } | |
1920 | EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); | |
1921 | ||
1922 | /** | |
1923 | * cgroup_taskset_size - return the number of tasks in taskset | |
1924 | * @tset: taskset of interest | |
1925 | */ | |
1926 | int cgroup_taskset_size(struct cgroup_taskset *tset) | |
1927 | { | |
1928 | return tset->tc_array ? tset->tc_array_len : 1; | |
1929 | } | |
1930 | EXPORT_SYMBOL_GPL(cgroup_taskset_size); | |
1931 | ||
1932 | ||
74a1166d BB |
1933 | /* |
1934 | * cgroup_task_migrate - move a task from one cgroup to another. | |
1935 | * | |
d0b2fdd2 | 1936 | * Must be called with cgroup_mutex and threadgroup locked. |
74a1166d | 1937 | */ |
5abb8855 TH |
1938 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
1939 | struct task_struct *tsk, | |
1940 | struct css_set *new_cset) | |
74a1166d | 1941 | { |
5abb8855 | 1942 | struct css_set *old_cset; |
74a1166d BB |
1943 | |
1944 | /* | |
026085ef MSB |
1945 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1946 | * setting such that we can't race against cgroup_exit() changing the | |
1947 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1948 | */ |
c84cdf75 | 1949 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
5abb8855 | 1950 | old_cset = tsk->cgroups; |
74a1166d | 1951 | |
74a1166d | 1952 | task_lock(tsk); |
5abb8855 | 1953 | rcu_assign_pointer(tsk->cgroups, new_cset); |
74a1166d BB |
1954 | task_unlock(tsk); |
1955 | ||
1956 | /* Update the css_set linked lists if we're using them */ | |
1957 | write_lock(&css_set_lock); | |
1958 | if (!list_empty(&tsk->cg_list)) | |
5abb8855 | 1959 | list_move(&tsk->cg_list, &new_cset->tasks); |
74a1166d BB |
1960 | write_unlock(&css_set_lock); |
1961 | ||
1962 | /* | |
5abb8855 TH |
1963 | * We just gained a reference on old_cset by taking it from the |
1964 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
1965 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 1966 | */ |
5abb8855 TH |
1967 | set_bit(CGRP_RELEASABLE, &old_cgrp->flags); |
1968 | put_css_set(old_cset); | |
74a1166d BB |
1969 | } |
1970 | ||
a043e3b2 | 1971 | /** |
081aa458 | 1972 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup |
74a1166d | 1973 | * @cgrp: the cgroup to attach to |
081aa458 LZ |
1974 | * @tsk: the task or the leader of the threadgroup to be attached |
1975 | * @threadgroup: attach the whole threadgroup? | |
74a1166d | 1976 | * |
257058ae | 1977 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take |
081aa458 | 1978 | * task_lock of @tsk or each thread in the threadgroup individually in turn. |
74a1166d | 1979 | */ |
47cfcd09 TH |
1980 | static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, |
1981 | bool threadgroup) | |
74a1166d BB |
1982 | { |
1983 | int retval, i, group_size; | |
1984 | struct cgroup_subsys *ss, *failed_ss = NULL; | |
74a1166d BB |
1985 | struct cgroupfs_root *root = cgrp->root; |
1986 | /* threadgroup list cursor and array */ | |
081aa458 | 1987 | struct task_struct *leader = tsk; |
134d3373 | 1988 | struct task_and_cgroup *tc; |
d846687d | 1989 | struct flex_array *group; |
2f7ee569 | 1990 | struct cgroup_taskset tset = { }; |
74a1166d BB |
1991 | |
1992 | /* | |
1993 | * step 0: in order to do expensive, possibly blocking operations for | |
1994 | * every thread, we cannot iterate the thread group list, since it needs | |
1995 | * rcu or tasklist locked. instead, build an array of all threads in the | |
257058ae TH |
1996 | * group - group_rwsem prevents new threads from appearing, and if |
1997 | * threads exit, this will just be an over-estimate. | |
74a1166d | 1998 | */ |
081aa458 LZ |
1999 | if (threadgroup) |
2000 | group_size = get_nr_threads(tsk); | |
2001 | else | |
2002 | group_size = 1; | |
d846687d | 2003 | /* flex_array supports very large thread-groups better than kmalloc. */ |
134d3373 | 2004 | group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); |
74a1166d BB |
2005 | if (!group) |
2006 | return -ENOMEM; | |
d846687d | 2007 | /* pre-allocate to guarantee space while iterating in rcu read-side. */ |
3ac1707a | 2008 | retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); |
d846687d BB |
2009 | if (retval) |
2010 | goto out_free_group_list; | |
74a1166d | 2011 | |
74a1166d | 2012 | i = 0; |
fb5d2b4c MSB |
2013 | /* |
2014 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2015 | * already PF_EXITING could be freed from underneath us unless we | |
2016 | * take an rcu_read_lock. | |
2017 | */ | |
2018 | rcu_read_lock(); | |
74a1166d | 2019 | do { |
134d3373 TH |
2020 | struct task_and_cgroup ent; |
2021 | ||
cd3d0952 TH |
2022 | /* @tsk either already exited or can't exit until the end */ |
2023 | if (tsk->flags & PF_EXITING) | |
2024 | continue; | |
2025 | ||
74a1166d BB |
2026 | /* as per above, nr_threads may decrease, but not increase. */ |
2027 | BUG_ON(i >= group_size); | |
134d3373 TH |
2028 | ent.task = tsk; |
2029 | ent.cgrp = task_cgroup_from_root(tsk, root); | |
892a2b90 MSB |
2030 | /* nothing to do if this task is already in the cgroup */ |
2031 | if (ent.cgrp == cgrp) | |
2032 | continue; | |
61d1d219 MSB |
2033 | /* |
2034 | * saying GFP_ATOMIC has no effect here because we did prealloc | |
2035 | * earlier, but it's good form to communicate our expectations. | |
2036 | */ | |
134d3373 | 2037 | retval = flex_array_put(group, i, &ent, GFP_ATOMIC); |
d846687d | 2038 | BUG_ON(retval != 0); |
74a1166d | 2039 | i++; |
081aa458 LZ |
2040 | |
2041 | if (!threadgroup) | |
2042 | break; | |
74a1166d | 2043 | } while_each_thread(leader, tsk); |
fb5d2b4c | 2044 | rcu_read_unlock(); |
74a1166d BB |
2045 | /* remember the number of threads in the array for later. */ |
2046 | group_size = i; | |
2f7ee569 TH |
2047 | tset.tc_array = group; |
2048 | tset.tc_array_len = group_size; | |
74a1166d | 2049 | |
134d3373 TH |
2050 | /* methods shouldn't be called if no task is actually migrating */ |
2051 | retval = 0; | |
892a2b90 | 2052 | if (!group_size) |
b07ef774 | 2053 | goto out_free_group_list; |
134d3373 | 2054 | |
74a1166d BB |
2055 | /* |
2056 | * step 1: check that we can legitimately attach to the cgroup. | |
2057 | */ | |
2058 | for_each_subsys(root, ss) { | |
2059 | if (ss->can_attach) { | |
761b3ef5 | 2060 | retval = ss->can_attach(cgrp, &tset); |
74a1166d BB |
2061 | if (retval) { |
2062 | failed_ss = ss; | |
2063 | goto out_cancel_attach; | |
2064 | } | |
2065 | } | |
74a1166d BB |
2066 | } |
2067 | ||
2068 | /* | |
2069 | * step 2: make sure css_sets exist for all threads to be migrated. | |
2070 | * we use find_css_set, which allocates a new one if necessary. | |
2071 | */ | |
74a1166d | 2072 | for (i = 0; i < group_size; i++) { |
134d3373 | 2073 | tc = flex_array_get(group, i); |
61d1d219 MSB |
2074 | tc->cg = find_css_set(tc->task->cgroups, cgrp); |
2075 | if (!tc->cg) { | |
2076 | retval = -ENOMEM; | |
2077 | goto out_put_css_set_refs; | |
74a1166d BB |
2078 | } |
2079 | } | |
2080 | ||
2081 | /* | |
494c167c TH |
2082 | * step 3: now that we're guaranteed success wrt the css_sets, |
2083 | * proceed to move all tasks to the new cgroup. There are no | |
2084 | * failure cases after here, so this is the commit point. | |
74a1166d | 2085 | */ |
74a1166d | 2086 | for (i = 0; i < group_size; i++) { |
134d3373 | 2087 | tc = flex_array_get(group, i); |
1e2ccd1c | 2088 | cgroup_task_migrate(tc->cgrp, tc->task, tc->cg); |
74a1166d BB |
2089 | } |
2090 | /* nothing is sensitive to fork() after this point. */ | |
2091 | ||
2092 | /* | |
494c167c | 2093 | * step 4: do subsystem attach callbacks. |
74a1166d BB |
2094 | */ |
2095 | for_each_subsys(root, ss) { | |
2096 | if (ss->attach) | |
761b3ef5 | 2097 | ss->attach(cgrp, &tset); |
74a1166d BB |
2098 | } |
2099 | ||
2100 | /* | |
2101 | * step 5: success! and cleanup | |
2102 | */ | |
74a1166d | 2103 | retval = 0; |
61d1d219 MSB |
2104 | out_put_css_set_refs: |
2105 | if (retval) { | |
2106 | for (i = 0; i < group_size; i++) { | |
2107 | tc = flex_array_get(group, i); | |
2108 | if (!tc->cg) | |
2109 | break; | |
2110 | put_css_set(tc->cg); | |
2111 | } | |
74a1166d BB |
2112 | } |
2113 | out_cancel_attach: | |
74a1166d BB |
2114 | if (retval) { |
2115 | for_each_subsys(root, ss) { | |
494c167c | 2116 | if (ss == failed_ss) |
74a1166d | 2117 | break; |
74a1166d | 2118 | if (ss->cancel_attach) |
761b3ef5 | 2119 | ss->cancel_attach(cgrp, &tset); |
74a1166d BB |
2120 | } |
2121 | } | |
74a1166d | 2122 | out_free_group_list: |
d846687d | 2123 | flex_array_free(group); |
74a1166d BB |
2124 | return retval; |
2125 | } | |
2126 | ||
2127 | /* | |
2128 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 TH |
2129 | * function to attach either it or all tasks in its threadgroup. Will lock |
2130 | * cgroup_mutex and threadgroup; may take task_lock of task. | |
bbcb81d0 | 2131 | */ |
74a1166d | 2132 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2133 | { |
bbcb81d0 | 2134 | struct task_struct *tsk; |
c69e8d9c | 2135 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2136 | int ret; |
2137 | ||
74a1166d BB |
2138 | if (!cgroup_lock_live_group(cgrp)) |
2139 | return -ENODEV; | |
2140 | ||
b78949eb MSB |
2141 | retry_find_task: |
2142 | rcu_read_lock(); | |
bbcb81d0 | 2143 | if (pid) { |
73507f33 | 2144 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2145 | if (!tsk) { |
2146 | rcu_read_unlock(); | |
b78949eb MSB |
2147 | ret= -ESRCH; |
2148 | goto out_unlock_cgroup; | |
bbcb81d0 | 2149 | } |
74a1166d BB |
2150 | /* |
2151 | * even if we're attaching all tasks in the thread group, we | |
2152 | * only need to check permissions on one of them. | |
2153 | */ | |
c69e8d9c | 2154 | tcred = __task_cred(tsk); |
14a590c3 EB |
2155 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
2156 | !uid_eq(cred->euid, tcred->uid) && | |
2157 | !uid_eq(cred->euid, tcred->suid)) { | |
c69e8d9c | 2158 | rcu_read_unlock(); |
b78949eb MSB |
2159 | ret = -EACCES; |
2160 | goto out_unlock_cgroup; | |
bbcb81d0 | 2161 | } |
b78949eb MSB |
2162 | } else |
2163 | tsk = current; | |
cd3d0952 TH |
2164 | |
2165 | if (threadgroup) | |
b78949eb | 2166 | tsk = tsk->group_leader; |
c4c27fbd MG |
2167 | |
2168 | /* | |
14a40ffc | 2169 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2170 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2171 | * with no rt_runtime allocated. Just say no. | |
2172 | */ | |
14a40ffc | 2173 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd MG |
2174 | ret = -EINVAL; |
2175 | rcu_read_unlock(); | |
2176 | goto out_unlock_cgroup; | |
2177 | } | |
2178 | ||
b78949eb MSB |
2179 | get_task_struct(tsk); |
2180 | rcu_read_unlock(); | |
2181 | ||
2182 | threadgroup_lock(tsk); | |
2183 | if (threadgroup) { | |
2184 | if (!thread_group_leader(tsk)) { | |
2185 | /* | |
2186 | * a race with de_thread from another thread's exec() | |
2187 | * may strip us of our leadership, if this happens, | |
2188 | * there is no choice but to throw this task away and | |
2189 | * try again; this is | |
2190 | * "double-double-toil-and-trouble-check locking". | |
2191 | */ | |
2192 | threadgroup_unlock(tsk); | |
2193 | put_task_struct(tsk); | |
2194 | goto retry_find_task; | |
2195 | } | |
081aa458 LZ |
2196 | } |
2197 | ||
2198 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
2199 | ||
cd3d0952 TH |
2200 | threadgroup_unlock(tsk); |
2201 | ||
bbcb81d0 | 2202 | put_task_struct(tsk); |
b78949eb | 2203 | out_unlock_cgroup: |
47cfcd09 | 2204 | mutex_unlock(&cgroup_mutex); |
bbcb81d0 PM |
2205 | return ret; |
2206 | } | |
2207 | ||
7ae1bad9 TH |
2208 | /** |
2209 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2210 | * @from: attach to all cgroups of a given task | |
2211 | * @tsk: the task to be attached | |
2212 | */ | |
2213 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2214 | { | |
2215 | struct cgroupfs_root *root; | |
2216 | int retval = 0; | |
2217 | ||
47cfcd09 | 2218 | mutex_lock(&cgroup_mutex); |
7ae1bad9 TH |
2219 | for_each_active_root(root) { |
2220 | struct cgroup *from_cg = task_cgroup_from_root(from, root); | |
2221 | ||
2222 | retval = cgroup_attach_task(from_cg, tsk, false); | |
2223 | if (retval) | |
2224 | break; | |
2225 | } | |
47cfcd09 | 2226 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2227 | |
2228 | return retval; | |
2229 | } | |
2230 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2231 | ||
af351026 | 2232 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
74a1166d BB |
2233 | { |
2234 | return attach_task_by_pid(cgrp, pid, false); | |
2235 | } | |
2236 | ||
2237 | static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) | |
af351026 | 2238 | { |
b78949eb | 2239 | return attach_task_by_pid(cgrp, tgid, true); |
af351026 PM |
2240 | } |
2241 | ||
e788e066 PM |
2242 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, |
2243 | const char *buffer) | |
2244 | { | |
2245 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); | |
f4a2589f EK |
2246 | if (strlen(buffer) >= PATH_MAX) |
2247 | return -EINVAL; | |
e788e066 PM |
2248 | if (!cgroup_lock_live_group(cgrp)) |
2249 | return -ENODEV; | |
e25e2cbb | 2250 | mutex_lock(&cgroup_root_mutex); |
e788e066 | 2251 | strcpy(cgrp->root->release_agent_path, buffer); |
e25e2cbb | 2252 | mutex_unlock(&cgroup_root_mutex); |
47cfcd09 | 2253 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2254 | return 0; |
2255 | } | |
2256 | ||
2257 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, | |
2258 | struct seq_file *seq) | |
2259 | { | |
2260 | if (!cgroup_lock_live_group(cgrp)) | |
2261 | return -ENODEV; | |
2262 | seq_puts(seq, cgrp->root->release_agent_path); | |
2263 | seq_putc(seq, '\n'); | |
47cfcd09 | 2264 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2265 | return 0; |
2266 | } | |
2267 | ||
873fe09e TH |
2268 | static int cgroup_sane_behavior_show(struct cgroup *cgrp, struct cftype *cft, |
2269 | struct seq_file *seq) | |
2270 | { | |
2271 | seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); | |
e788e066 PM |
2272 | return 0; |
2273 | } | |
2274 | ||
84eea842 PM |
2275 | /* A buffer size big enough for numbers or short strings */ |
2276 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
2277 | ||
e73d2c61 | 2278 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
f4c753b7 PM |
2279 | struct file *file, |
2280 | const char __user *userbuf, | |
2281 | size_t nbytes, loff_t *unused_ppos) | |
355e0c48 | 2282 | { |
84eea842 | 2283 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
355e0c48 | 2284 | int retval = 0; |
355e0c48 PM |
2285 | char *end; |
2286 | ||
2287 | if (!nbytes) | |
2288 | return -EINVAL; | |
2289 | if (nbytes >= sizeof(buffer)) | |
2290 | return -E2BIG; | |
2291 | if (copy_from_user(buffer, userbuf, nbytes)) | |
2292 | return -EFAULT; | |
2293 | ||
2294 | buffer[nbytes] = 0; /* nul-terminate */ | |
e73d2c61 | 2295 | if (cft->write_u64) { |
478988d3 | 2296 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2297 | if (*end) |
2298 | return -EINVAL; | |
2299 | retval = cft->write_u64(cgrp, cft, val); | |
2300 | } else { | |
478988d3 | 2301 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2302 | if (*end) |
2303 | return -EINVAL; | |
2304 | retval = cft->write_s64(cgrp, cft, val); | |
2305 | } | |
355e0c48 PM |
2306 | if (!retval) |
2307 | retval = nbytes; | |
2308 | return retval; | |
2309 | } | |
2310 | ||
db3b1497 PM |
2311 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
2312 | struct file *file, | |
2313 | const char __user *userbuf, | |
2314 | size_t nbytes, loff_t *unused_ppos) | |
2315 | { | |
84eea842 | 2316 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
db3b1497 PM |
2317 | int retval = 0; |
2318 | size_t max_bytes = cft->max_write_len; | |
2319 | char *buffer = local_buffer; | |
2320 | ||
2321 | if (!max_bytes) | |
2322 | max_bytes = sizeof(local_buffer) - 1; | |
2323 | if (nbytes >= max_bytes) | |
2324 | return -E2BIG; | |
2325 | /* Allocate a dynamic buffer if we need one */ | |
2326 | if (nbytes >= sizeof(local_buffer)) { | |
2327 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
2328 | if (buffer == NULL) | |
2329 | return -ENOMEM; | |
2330 | } | |
5a3eb9f6 LZ |
2331 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
2332 | retval = -EFAULT; | |
2333 | goto out; | |
2334 | } | |
db3b1497 PM |
2335 | |
2336 | buffer[nbytes] = 0; /* nul-terminate */ | |
478988d3 | 2337 | retval = cft->write_string(cgrp, cft, strstrip(buffer)); |
db3b1497 PM |
2338 | if (!retval) |
2339 | retval = nbytes; | |
5a3eb9f6 | 2340 | out: |
db3b1497 PM |
2341 | if (buffer != local_buffer) |
2342 | kfree(buffer); | |
2343 | return retval; | |
2344 | } | |
2345 | ||
ddbcc7e8 PM |
2346 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
2347 | size_t nbytes, loff_t *ppos) | |
2348 | { | |
2349 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2350 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2351 | |
54766d4a | 2352 | if (cgroup_is_dead(cgrp)) |
ddbcc7e8 | 2353 | return -ENODEV; |
355e0c48 | 2354 | if (cft->write) |
bd89aabc | 2355 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
e73d2c61 PM |
2356 | if (cft->write_u64 || cft->write_s64) |
2357 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); | |
db3b1497 PM |
2358 | if (cft->write_string) |
2359 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); | |
d447ea2f PE |
2360 | if (cft->trigger) { |
2361 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); | |
2362 | return ret ? ret : nbytes; | |
2363 | } | |
355e0c48 | 2364 | return -EINVAL; |
ddbcc7e8 PM |
2365 | } |
2366 | ||
f4c753b7 PM |
2367 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
2368 | struct file *file, | |
2369 | char __user *buf, size_t nbytes, | |
2370 | loff_t *ppos) | |
ddbcc7e8 | 2371 | { |
84eea842 | 2372 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
f4c753b7 | 2373 | u64 val = cft->read_u64(cgrp, cft); |
ddbcc7e8 PM |
2374 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
2375 | ||
2376 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2377 | } | |
2378 | ||
e73d2c61 PM |
2379 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
2380 | struct file *file, | |
2381 | char __user *buf, size_t nbytes, | |
2382 | loff_t *ppos) | |
2383 | { | |
84eea842 | 2384 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
e73d2c61 PM |
2385 | s64 val = cft->read_s64(cgrp, cft); |
2386 | int len = sprintf(tmp, "%lld\n", (long long) val); | |
2387 | ||
2388 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2389 | } | |
2390 | ||
ddbcc7e8 PM |
2391 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
2392 | size_t nbytes, loff_t *ppos) | |
2393 | { | |
2394 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2395 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2396 | |
54766d4a | 2397 | if (cgroup_is_dead(cgrp)) |
ddbcc7e8 PM |
2398 | return -ENODEV; |
2399 | ||
2400 | if (cft->read) | |
bd89aabc | 2401 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
f4c753b7 PM |
2402 | if (cft->read_u64) |
2403 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); | |
e73d2c61 PM |
2404 | if (cft->read_s64) |
2405 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); | |
ddbcc7e8 PM |
2406 | return -EINVAL; |
2407 | } | |
2408 | ||
91796569 PM |
2409 | /* |
2410 | * seqfile ops/methods for returning structured data. Currently just | |
2411 | * supports string->u64 maps, but can be extended in future. | |
2412 | */ | |
2413 | ||
2414 | struct cgroup_seqfile_state { | |
2415 | struct cftype *cft; | |
2416 | struct cgroup *cgroup; | |
2417 | }; | |
2418 | ||
2419 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) | |
2420 | { | |
2421 | struct seq_file *sf = cb->state; | |
2422 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
2423 | } | |
2424 | ||
2425 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
2426 | { | |
2427 | struct cgroup_seqfile_state *state = m->private; | |
2428 | struct cftype *cft = state->cft; | |
29486df3 SH |
2429 | if (cft->read_map) { |
2430 | struct cgroup_map_cb cb = { | |
2431 | .fill = cgroup_map_add, | |
2432 | .state = m, | |
2433 | }; | |
2434 | return cft->read_map(state->cgroup, cft, &cb); | |
2435 | } | |
2436 | return cft->read_seq_string(state->cgroup, cft, m); | |
91796569 PM |
2437 | } |
2438 | ||
96930a63 | 2439 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
91796569 PM |
2440 | { |
2441 | struct seq_file *seq = file->private_data; | |
2442 | kfree(seq->private); | |
2443 | return single_release(inode, file); | |
2444 | } | |
2445 | ||
828c0950 | 2446 | static const struct file_operations cgroup_seqfile_operations = { |
91796569 | 2447 | .read = seq_read, |
e788e066 | 2448 | .write = cgroup_file_write, |
91796569 PM |
2449 | .llseek = seq_lseek, |
2450 | .release = cgroup_seqfile_release, | |
2451 | }; | |
2452 | ||
ddbcc7e8 PM |
2453 | static int cgroup_file_open(struct inode *inode, struct file *file) |
2454 | { | |
2455 | int err; | |
2456 | struct cftype *cft; | |
2457 | ||
2458 | err = generic_file_open(inode, file); | |
2459 | if (err) | |
2460 | return err; | |
ddbcc7e8 | 2461 | cft = __d_cft(file->f_dentry); |
75139b82 | 2462 | |
29486df3 | 2463 | if (cft->read_map || cft->read_seq_string) { |
f4f4be2b TH |
2464 | struct cgroup_seqfile_state *state; |
2465 | ||
2466 | state = kzalloc(sizeof(*state), GFP_USER); | |
91796569 PM |
2467 | if (!state) |
2468 | return -ENOMEM; | |
f4f4be2b | 2469 | |
91796569 PM |
2470 | state->cft = cft; |
2471 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); | |
2472 | file->f_op = &cgroup_seqfile_operations; | |
2473 | err = single_open(file, cgroup_seqfile_show, state); | |
2474 | if (err < 0) | |
2475 | kfree(state); | |
2476 | } else if (cft->open) | |
ddbcc7e8 PM |
2477 | err = cft->open(inode, file); |
2478 | else | |
2479 | err = 0; | |
2480 | ||
2481 | return err; | |
2482 | } | |
2483 | ||
2484 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
2485 | { | |
2486 | struct cftype *cft = __d_cft(file->f_dentry); | |
2487 | if (cft->release) | |
2488 | return cft->release(inode, file); | |
2489 | return 0; | |
2490 | } | |
2491 | ||
2492 | /* | |
2493 | * cgroup_rename - Only allow simple rename of directories in place. | |
2494 | */ | |
2495 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2496 | struct inode *new_dir, struct dentry *new_dentry) | |
2497 | { | |
65dff759 LZ |
2498 | int ret; |
2499 | struct cgroup_name *name, *old_name; | |
2500 | struct cgroup *cgrp; | |
2501 | ||
2502 | /* | |
2503 | * It's convinient to use parent dir's i_mutex to protected | |
2504 | * cgrp->name. | |
2505 | */ | |
2506 | lockdep_assert_held(&old_dir->i_mutex); | |
2507 | ||
ddbcc7e8 PM |
2508 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) |
2509 | return -ENOTDIR; | |
2510 | if (new_dentry->d_inode) | |
2511 | return -EEXIST; | |
2512 | if (old_dir != new_dir) | |
2513 | return -EIO; | |
65dff759 LZ |
2514 | |
2515 | cgrp = __d_cgrp(old_dentry); | |
2516 | ||
6db8e85c TH |
2517 | /* |
2518 | * This isn't a proper migration and its usefulness is very | |
2519 | * limited. Disallow if sane_behavior. | |
2520 | */ | |
2521 | if (cgroup_sane_behavior(cgrp)) | |
2522 | return -EPERM; | |
2523 | ||
65dff759 LZ |
2524 | name = cgroup_alloc_name(new_dentry); |
2525 | if (!name) | |
2526 | return -ENOMEM; | |
2527 | ||
2528 | ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2529 | if (ret) { | |
2530 | kfree(name); | |
2531 | return ret; | |
2532 | } | |
2533 | ||
2534 | old_name = cgrp->name; | |
2535 | rcu_assign_pointer(cgrp->name, name); | |
2536 | ||
2537 | kfree_rcu(old_name, rcu_head); | |
2538 | return 0; | |
ddbcc7e8 PM |
2539 | } |
2540 | ||
03b1cde6 AR |
2541 | static struct simple_xattrs *__d_xattrs(struct dentry *dentry) |
2542 | { | |
2543 | if (S_ISDIR(dentry->d_inode->i_mode)) | |
2544 | return &__d_cgrp(dentry)->xattrs; | |
2545 | else | |
712317ad | 2546 | return &__d_cfe(dentry)->xattrs; |
03b1cde6 AR |
2547 | } |
2548 | ||
2549 | static inline int xattr_enabled(struct dentry *dentry) | |
2550 | { | |
2551 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; | |
93438629 | 2552 | return root->flags & CGRP_ROOT_XATTR; |
03b1cde6 AR |
2553 | } |
2554 | ||
2555 | static bool is_valid_xattr(const char *name) | |
2556 | { | |
2557 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || | |
2558 | !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) | |
2559 | return true; | |
2560 | return false; | |
2561 | } | |
2562 | ||
2563 | static int cgroup_setxattr(struct dentry *dentry, const char *name, | |
2564 | const void *val, size_t size, int flags) | |
2565 | { | |
2566 | if (!xattr_enabled(dentry)) | |
2567 | return -EOPNOTSUPP; | |
2568 | if (!is_valid_xattr(name)) | |
2569 | return -EINVAL; | |
2570 | return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); | |
2571 | } | |
2572 | ||
2573 | static int cgroup_removexattr(struct dentry *dentry, const char *name) | |
2574 | { | |
2575 | if (!xattr_enabled(dentry)) | |
2576 | return -EOPNOTSUPP; | |
2577 | if (!is_valid_xattr(name)) | |
2578 | return -EINVAL; | |
2579 | return simple_xattr_remove(__d_xattrs(dentry), name); | |
2580 | } | |
2581 | ||
2582 | static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, | |
2583 | void *buf, size_t size) | |
2584 | { | |
2585 | if (!xattr_enabled(dentry)) | |
2586 | return -EOPNOTSUPP; | |
2587 | if (!is_valid_xattr(name)) | |
2588 | return -EINVAL; | |
2589 | return simple_xattr_get(__d_xattrs(dentry), name, buf, size); | |
2590 | } | |
2591 | ||
2592 | static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) | |
2593 | { | |
2594 | if (!xattr_enabled(dentry)) | |
2595 | return -EOPNOTSUPP; | |
2596 | return simple_xattr_list(__d_xattrs(dentry), buf, size); | |
2597 | } | |
2598 | ||
828c0950 | 2599 | static const struct file_operations cgroup_file_operations = { |
ddbcc7e8 PM |
2600 | .read = cgroup_file_read, |
2601 | .write = cgroup_file_write, | |
2602 | .llseek = generic_file_llseek, | |
2603 | .open = cgroup_file_open, | |
2604 | .release = cgroup_file_release, | |
2605 | }; | |
2606 | ||
03b1cde6 AR |
2607 | static const struct inode_operations cgroup_file_inode_operations = { |
2608 | .setxattr = cgroup_setxattr, | |
2609 | .getxattr = cgroup_getxattr, | |
2610 | .listxattr = cgroup_listxattr, | |
2611 | .removexattr = cgroup_removexattr, | |
2612 | }; | |
2613 | ||
6e1d5dcc | 2614 | static const struct inode_operations cgroup_dir_inode_operations = { |
c72a04e3 | 2615 | .lookup = cgroup_lookup, |
ddbcc7e8 PM |
2616 | .mkdir = cgroup_mkdir, |
2617 | .rmdir = cgroup_rmdir, | |
2618 | .rename = cgroup_rename, | |
03b1cde6 AR |
2619 | .setxattr = cgroup_setxattr, |
2620 | .getxattr = cgroup_getxattr, | |
2621 | .listxattr = cgroup_listxattr, | |
2622 | .removexattr = cgroup_removexattr, | |
ddbcc7e8 PM |
2623 | }; |
2624 | ||
00cd8dd3 | 2625 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
c72a04e3 AV |
2626 | { |
2627 | if (dentry->d_name.len > NAME_MAX) | |
2628 | return ERR_PTR(-ENAMETOOLONG); | |
2629 | d_add(dentry, NULL); | |
2630 | return NULL; | |
2631 | } | |
2632 | ||
0dea1168 KS |
2633 | /* |
2634 | * Check if a file is a control file | |
2635 | */ | |
2636 | static inline struct cftype *__file_cft(struct file *file) | |
2637 | { | |
496ad9aa | 2638 | if (file_inode(file)->i_fop != &cgroup_file_operations) |
0dea1168 KS |
2639 | return ERR_PTR(-EINVAL); |
2640 | return __d_cft(file->f_dentry); | |
2641 | } | |
2642 | ||
a5e7ed32 | 2643 | static int cgroup_create_file(struct dentry *dentry, umode_t mode, |
5adcee1d NP |
2644 | struct super_block *sb) |
2645 | { | |
ddbcc7e8 PM |
2646 | struct inode *inode; |
2647 | ||
2648 | if (!dentry) | |
2649 | return -ENOENT; | |
2650 | if (dentry->d_inode) | |
2651 | return -EEXIST; | |
2652 | ||
2653 | inode = cgroup_new_inode(mode, sb); | |
2654 | if (!inode) | |
2655 | return -ENOMEM; | |
2656 | ||
2657 | if (S_ISDIR(mode)) { | |
2658 | inode->i_op = &cgroup_dir_inode_operations; | |
2659 | inode->i_fop = &simple_dir_operations; | |
2660 | ||
2661 | /* start off with i_nlink == 2 (for "." entry) */ | |
2662 | inc_nlink(inode); | |
28fd6f30 | 2663 | inc_nlink(dentry->d_parent->d_inode); |
ddbcc7e8 | 2664 | |
b8a2df6a TH |
2665 | /* |
2666 | * Control reaches here with cgroup_mutex held. | |
2667 | * @inode->i_mutex should nest outside cgroup_mutex but we | |
2668 | * want to populate it immediately without releasing | |
2669 | * cgroup_mutex. As @inode isn't visible to anyone else | |
2670 | * yet, trylock will always succeed without affecting | |
2671 | * lockdep checks. | |
2672 | */ | |
2673 | WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex)); | |
ddbcc7e8 PM |
2674 | } else if (S_ISREG(mode)) { |
2675 | inode->i_size = 0; | |
2676 | inode->i_fop = &cgroup_file_operations; | |
03b1cde6 | 2677 | inode->i_op = &cgroup_file_inode_operations; |
ddbcc7e8 | 2678 | } |
ddbcc7e8 PM |
2679 | d_instantiate(dentry, inode); |
2680 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2681 | return 0; | |
2682 | } | |
2683 | ||
099fca32 LZ |
2684 | /** |
2685 | * cgroup_file_mode - deduce file mode of a control file | |
2686 | * @cft: the control file in question | |
2687 | * | |
2688 | * returns cft->mode if ->mode is not 0 | |
2689 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
2690 | * returns S_IRUGO if it has only a read handler | |
2691 | * returns S_IWUSR if it has only a write hander | |
2692 | */ | |
a5e7ed32 | 2693 | static umode_t cgroup_file_mode(const struct cftype *cft) |
099fca32 | 2694 | { |
a5e7ed32 | 2695 | umode_t mode = 0; |
099fca32 LZ |
2696 | |
2697 | if (cft->mode) | |
2698 | return cft->mode; | |
2699 | ||
2700 | if (cft->read || cft->read_u64 || cft->read_s64 || | |
2701 | cft->read_map || cft->read_seq_string) | |
2702 | mode |= S_IRUGO; | |
2703 | ||
2704 | if (cft->write || cft->write_u64 || cft->write_s64 || | |
2705 | cft->write_string || cft->trigger) | |
2706 | mode |= S_IWUSR; | |
2707 | ||
2708 | return mode; | |
2709 | } | |
2710 | ||
db0416b6 | 2711 | static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
03b1cde6 | 2712 | struct cftype *cft) |
ddbcc7e8 | 2713 | { |
bd89aabc | 2714 | struct dentry *dir = cgrp->dentry; |
05ef1d7c | 2715 | struct cgroup *parent = __d_cgrp(dir); |
ddbcc7e8 | 2716 | struct dentry *dentry; |
05ef1d7c | 2717 | struct cfent *cfe; |
ddbcc7e8 | 2718 | int error; |
a5e7ed32 | 2719 | umode_t mode; |
ddbcc7e8 | 2720 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; |
8e3f6541 | 2721 | |
93438629 | 2722 | if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { |
ddbcc7e8 PM |
2723 | strcpy(name, subsys->name); |
2724 | strcat(name, "."); | |
2725 | } | |
2726 | strcat(name, cft->name); | |
05ef1d7c | 2727 | |
ddbcc7e8 | 2728 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); |
05ef1d7c TH |
2729 | |
2730 | cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); | |
2731 | if (!cfe) | |
2732 | return -ENOMEM; | |
2733 | ||
ddbcc7e8 | 2734 | dentry = lookup_one_len(name, dir, strlen(name)); |
05ef1d7c | 2735 | if (IS_ERR(dentry)) { |
ddbcc7e8 | 2736 | error = PTR_ERR(dentry); |
05ef1d7c TH |
2737 | goto out; |
2738 | } | |
2739 | ||
d6cbf35d LZ |
2740 | cfe->type = (void *)cft; |
2741 | cfe->dentry = dentry; | |
2742 | dentry->d_fsdata = cfe; | |
2743 | simple_xattrs_init(&cfe->xattrs); | |
2744 | ||
05ef1d7c TH |
2745 | mode = cgroup_file_mode(cft); |
2746 | error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); | |
2747 | if (!error) { | |
05ef1d7c TH |
2748 | list_add_tail(&cfe->node, &parent->files); |
2749 | cfe = NULL; | |
2750 | } | |
2751 | dput(dentry); | |
2752 | out: | |
2753 | kfree(cfe); | |
ddbcc7e8 PM |
2754 | return error; |
2755 | } | |
2756 | ||
79578621 | 2757 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
03b1cde6 | 2758 | struct cftype cfts[], bool is_add) |
ddbcc7e8 | 2759 | { |
03b1cde6 | 2760 | struct cftype *cft; |
db0416b6 TH |
2761 | int err, ret = 0; |
2762 | ||
2763 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 2764 | /* does cft->flags tell us to skip this file on @cgrp? */ |
873fe09e TH |
2765 | if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) |
2766 | continue; | |
f33fddc2 G |
2767 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) |
2768 | continue; | |
2769 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2770 | continue; | |
2771 | ||
2739d3cc | 2772 | if (is_add) { |
79578621 | 2773 | err = cgroup_add_file(cgrp, subsys, cft); |
2739d3cc LZ |
2774 | if (err) |
2775 | pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", | |
2776 | cft->name, err); | |
db0416b6 | 2777 | ret = err; |
2739d3cc LZ |
2778 | } else { |
2779 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 2780 | } |
ddbcc7e8 | 2781 | } |
db0416b6 | 2782 | return ret; |
ddbcc7e8 PM |
2783 | } |
2784 | ||
8e3f6541 | 2785 | static void cgroup_cfts_prepare(void) |
e8c82d20 | 2786 | __acquires(&cgroup_mutex) |
8e3f6541 TH |
2787 | { |
2788 | /* | |
2789 | * Thanks to the entanglement with vfs inode locking, we can't walk | |
2790 | * the existing cgroups under cgroup_mutex and create files. | |
e8c82d20 LZ |
2791 | * Instead, we use cgroup_for_each_descendant_pre() and drop RCU |
2792 | * read lock before calling cgroup_addrm_files(). | |
8e3f6541 | 2793 | */ |
8e3f6541 TH |
2794 | mutex_lock(&cgroup_mutex); |
2795 | } | |
2796 | ||
2797 | static void cgroup_cfts_commit(struct cgroup_subsys *ss, | |
03b1cde6 | 2798 | struct cftype *cfts, bool is_add) |
e8c82d20 | 2799 | __releases(&cgroup_mutex) |
8e3f6541 TH |
2800 | { |
2801 | LIST_HEAD(pending); | |
e8c82d20 | 2802 | struct cgroup *cgrp, *root = &ss->root->top_cgroup; |
084457f2 | 2803 | struct super_block *sb = ss->root->sb; |
e8c82d20 LZ |
2804 | struct dentry *prev = NULL; |
2805 | struct inode *inode; | |
2806 | u64 update_upto; | |
8e3f6541 TH |
2807 | |
2808 | /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ | |
e8c82d20 LZ |
2809 | if (!cfts || ss->root == &rootnode || |
2810 | !atomic_inc_not_zero(&sb->s_active)) { | |
2811 | mutex_unlock(&cgroup_mutex); | |
2812 | return; | |
8e3f6541 TH |
2813 | } |
2814 | ||
8e3f6541 | 2815 | /* |
e8c82d20 LZ |
2816 | * All cgroups which are created after we drop cgroup_mutex will |
2817 | * have the updated set of files, so we only need to update the | |
2818 | * cgroups created before the current @cgroup_serial_nr_cursor. | |
8e3f6541 | 2819 | */ |
e8c82d20 LZ |
2820 | update_upto = atomic64_read(&cgroup_serial_nr_cursor); |
2821 | ||
2822 | mutex_unlock(&cgroup_mutex); | |
2823 | ||
2824 | /* @root always needs to be updated */ | |
2825 | inode = root->dentry->d_inode; | |
2826 | mutex_lock(&inode->i_mutex); | |
2827 | mutex_lock(&cgroup_mutex); | |
2828 | cgroup_addrm_files(root, ss, cfts, is_add); | |
2829 | mutex_unlock(&cgroup_mutex); | |
2830 | mutex_unlock(&inode->i_mutex); | |
2831 | ||
2832 | /* add/rm files for all cgroups created before */ | |
2833 | rcu_read_lock(); | |
2834 | cgroup_for_each_descendant_pre(cgrp, root) { | |
2835 | if (cgroup_is_dead(cgrp)) | |
2836 | continue; | |
2837 | ||
2838 | inode = cgrp->dentry->d_inode; | |
2839 | dget(cgrp->dentry); | |
2840 | rcu_read_unlock(); | |
2841 | ||
2842 | dput(prev); | |
2843 | prev = cgrp->dentry; | |
8e3f6541 TH |
2844 | |
2845 | mutex_lock(&inode->i_mutex); | |
2846 | mutex_lock(&cgroup_mutex); | |
e8c82d20 | 2847 | if (cgrp->serial_nr <= update_upto && !cgroup_is_dead(cgrp)) |
79578621 | 2848 | cgroup_addrm_files(cgrp, ss, cfts, is_add); |
8e3f6541 TH |
2849 | mutex_unlock(&cgroup_mutex); |
2850 | mutex_unlock(&inode->i_mutex); | |
2851 | ||
e8c82d20 | 2852 | rcu_read_lock(); |
8e3f6541 | 2853 | } |
e8c82d20 LZ |
2854 | rcu_read_unlock(); |
2855 | dput(prev); | |
2856 | deactivate_super(sb); | |
8e3f6541 TH |
2857 | } |
2858 | ||
2859 | /** | |
2860 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2861 | * @ss: target cgroup subsystem | |
2862 | * @cfts: zero-length name terminated array of cftypes | |
2863 | * | |
2864 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2865 | * existing cgroups to which @ss is attached and all future cgroups will | |
2866 | * have them too. This function can be called anytime whether @ss is | |
2867 | * attached or not. | |
2868 | * | |
2869 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2870 | * function currently returns 0 as long as @cfts registration is successful | |
2871 | * even if some file creation attempts on existing cgroups fail. | |
2872 | */ | |
03b1cde6 | 2873 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 TH |
2874 | { |
2875 | struct cftype_set *set; | |
2876 | ||
2877 | set = kzalloc(sizeof(*set), GFP_KERNEL); | |
2878 | if (!set) | |
2879 | return -ENOMEM; | |
2880 | ||
2881 | cgroup_cfts_prepare(); | |
2882 | set->cfts = cfts; | |
2883 | list_add_tail(&set->node, &ss->cftsets); | |
79578621 | 2884 | cgroup_cfts_commit(ss, cfts, true); |
8e3f6541 TH |
2885 | |
2886 | return 0; | |
2887 | } | |
2888 | EXPORT_SYMBOL_GPL(cgroup_add_cftypes); | |
2889 | ||
79578621 TH |
2890 | /** |
2891 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
2892 | * @ss: target cgroup subsystem | |
2893 | * @cfts: zero-length name terminated array of cftypes | |
2894 | * | |
2895 | * Unregister @cfts from @ss. Files described by @cfts are removed from | |
2896 | * all existing cgroups to which @ss is attached and all future cgroups | |
2897 | * won't have them either. This function can be called anytime whether @ss | |
2898 | * is attached or not. | |
2899 | * | |
2900 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2901 | * registered with @ss. | |
2902 | */ | |
03b1cde6 | 2903 | int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
79578621 TH |
2904 | { |
2905 | struct cftype_set *set; | |
2906 | ||
2907 | cgroup_cfts_prepare(); | |
2908 | ||
2909 | list_for_each_entry(set, &ss->cftsets, node) { | |
2910 | if (set->cfts == cfts) { | |
f57947d2 LZ |
2911 | list_del(&set->node); |
2912 | kfree(set); | |
79578621 TH |
2913 | cgroup_cfts_commit(ss, cfts, false); |
2914 | return 0; | |
2915 | } | |
2916 | } | |
2917 | ||
2918 | cgroup_cfts_commit(ss, NULL, false); | |
2919 | return -ENOENT; | |
2920 | } | |
2921 | ||
a043e3b2 LZ |
2922 | /** |
2923 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2924 | * @cgrp: the cgroup in question | |
2925 | * | |
2926 | * Return the number of tasks in the cgroup. | |
2927 | */ | |
bd89aabc | 2928 | int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2929 | { |
2930 | int count = 0; | |
69d0206c | 2931 | struct cgrp_cset_link *link; |
817929ec PM |
2932 | |
2933 | read_lock(&css_set_lock); | |
69d0206c TH |
2934 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
2935 | count += atomic_read(&link->cset->refcount); | |
817929ec | 2936 | read_unlock(&css_set_lock); |
bbcb81d0 PM |
2937 | return count; |
2938 | } | |
2939 | ||
817929ec PM |
2940 | /* |
2941 | * Advance a list_head iterator. The iterator should be positioned at | |
2942 | * the start of a css_set | |
2943 | */ | |
69d0206c | 2944 | static void cgroup_advance_iter(struct cgroup *cgrp, struct cgroup_iter *it) |
817929ec | 2945 | { |
69d0206c TH |
2946 | struct list_head *l = it->cset_link; |
2947 | struct cgrp_cset_link *link; | |
5abb8855 | 2948 | struct css_set *cset; |
817929ec PM |
2949 | |
2950 | /* Advance to the next non-empty css_set */ | |
2951 | do { | |
2952 | l = l->next; | |
69d0206c TH |
2953 | if (l == &cgrp->cset_links) { |
2954 | it->cset_link = NULL; | |
817929ec PM |
2955 | return; |
2956 | } | |
69d0206c TH |
2957 | link = list_entry(l, struct cgrp_cset_link, cset_link); |
2958 | cset = link->cset; | |
5abb8855 | 2959 | } while (list_empty(&cset->tasks)); |
69d0206c | 2960 | it->cset_link = l; |
5abb8855 | 2961 | it->task = cset->tasks.next; |
817929ec PM |
2962 | } |
2963 | ||
31a7df01 CW |
2964 | /* |
2965 | * To reduce the fork() overhead for systems that are not actually | |
2966 | * using their cgroups capability, we don't maintain the lists running | |
2967 | * through each css_set to its tasks until we see the list actually | |
2968 | * used - in other words after the first call to cgroup_iter_start(). | |
31a7df01 | 2969 | */ |
3df91fe3 | 2970 | static void cgroup_enable_task_cg_lists(void) |
31a7df01 CW |
2971 | { |
2972 | struct task_struct *p, *g; | |
2973 | write_lock(&css_set_lock); | |
2974 | use_task_css_set_links = 1; | |
3ce3230a FW |
2975 | /* |
2976 | * We need tasklist_lock because RCU is not safe against | |
2977 | * while_each_thread(). Besides, a forking task that has passed | |
2978 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
2979 | * is not guaranteed to have its child immediately visible in the | |
2980 | * tasklist if we walk through it with RCU. | |
2981 | */ | |
2982 | read_lock(&tasklist_lock); | |
31a7df01 CW |
2983 | do_each_thread(g, p) { |
2984 | task_lock(p); | |
0e04388f LZ |
2985 | /* |
2986 | * We should check if the process is exiting, otherwise | |
2987 | * it will race with cgroup_exit() in that the list | |
2988 | * entry won't be deleted though the process has exited. | |
2989 | */ | |
2990 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
31a7df01 CW |
2991 | list_add(&p->cg_list, &p->cgroups->tasks); |
2992 | task_unlock(p); | |
2993 | } while_each_thread(g, p); | |
3ce3230a | 2994 | read_unlock(&tasklist_lock); |
31a7df01 CW |
2995 | write_unlock(&css_set_lock); |
2996 | } | |
2997 | ||
53fa5261 TH |
2998 | /** |
2999 | * cgroup_next_sibling - find the next sibling of a given cgroup | |
3000 | * @pos: the current cgroup | |
3001 | * | |
3002 | * This function returns the next sibling of @pos and should be called | |
3003 | * under RCU read lock. The only requirement is that @pos is accessible. | |
3004 | * The next sibling is guaranteed to be returned regardless of @pos's | |
3005 | * state. | |
3006 | */ | |
3007 | struct cgroup *cgroup_next_sibling(struct cgroup *pos) | |
3008 | { | |
3009 | struct cgroup *next; | |
3010 | ||
3011 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3012 | ||
3013 | /* | |
3014 | * @pos could already have been removed. Once a cgroup is removed, | |
3015 | * its ->sibling.next is no longer updated when its next sibling | |
ea15f8cc TH |
3016 | * changes. As CGRP_DEAD assertion is serialized and happens |
3017 | * before the cgroup is taken off the ->sibling list, if we see it | |
3018 | * unasserted, it's guaranteed that the next sibling hasn't | |
3019 | * finished its grace period even if it's already removed, and thus | |
3020 | * safe to dereference from this RCU critical section. If | |
3021 | * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed | |
3022 | * to be visible as %true here. | |
53fa5261 | 3023 | */ |
54766d4a | 3024 | if (likely(!cgroup_is_dead(pos))) { |
53fa5261 TH |
3025 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); |
3026 | if (&next->sibling != &pos->parent->children) | |
3027 | return next; | |
3028 | return NULL; | |
3029 | } | |
3030 | ||
3031 | /* | |
3032 | * Can't dereference the next pointer. Each cgroup is given a | |
3033 | * monotonically increasing unique serial number and always | |
3034 | * appended to the sibling list, so the next one can be found by | |
3035 | * walking the parent's children until we see a cgroup with higher | |
3036 | * serial number than @pos's. | |
3037 | * | |
3038 | * While this path can be slow, it's taken only when either the | |
3039 | * current cgroup is removed or iteration and removal race. | |
3040 | */ | |
3041 | list_for_each_entry_rcu(next, &pos->parent->children, sibling) | |
3042 | if (next->serial_nr > pos->serial_nr) | |
3043 | return next; | |
3044 | return NULL; | |
3045 | } | |
3046 | EXPORT_SYMBOL_GPL(cgroup_next_sibling); | |
3047 | ||
574bd9f7 TH |
3048 | /** |
3049 | * cgroup_next_descendant_pre - find the next descendant for pre-order walk | |
3050 | * @pos: the current position (%NULL to initiate traversal) | |
3051 | * @cgroup: cgroup whose descendants to walk | |
3052 | * | |
3053 | * To be used by cgroup_for_each_descendant_pre(). Find the next | |
3054 | * descendant to visit for pre-order traversal of @cgroup's descendants. | |
75501a6d TH |
3055 | * |
3056 | * While this function requires RCU read locking, it doesn't require the | |
3057 | * whole traversal to be contained in a single RCU critical section. This | |
3058 | * function will return the correct next descendant as long as both @pos | |
3059 | * and @cgroup are accessible and @pos is a descendant of @cgroup. | |
574bd9f7 TH |
3060 | */ |
3061 | struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, | |
3062 | struct cgroup *cgroup) | |
3063 | { | |
3064 | struct cgroup *next; | |
3065 | ||
3066 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3067 | ||
3068 | /* if first iteration, pretend we just visited @cgroup */ | |
7805d000 | 3069 | if (!pos) |
574bd9f7 | 3070 | pos = cgroup; |
574bd9f7 TH |
3071 | |
3072 | /* visit the first child if exists */ | |
3073 | next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling); | |
3074 | if (next) | |
3075 | return next; | |
3076 | ||
3077 | /* no child, visit my or the closest ancestor's next sibling */ | |
7805d000 | 3078 | while (pos != cgroup) { |
75501a6d TH |
3079 | next = cgroup_next_sibling(pos); |
3080 | if (next) | |
574bd9f7 | 3081 | return next; |
574bd9f7 | 3082 | pos = pos->parent; |
7805d000 | 3083 | } |
574bd9f7 TH |
3084 | |
3085 | return NULL; | |
3086 | } | |
3087 | EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre); | |
3088 | ||
12a9d2fe TH |
3089 | /** |
3090 | * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup | |
3091 | * @pos: cgroup of interest | |
3092 | * | |
3093 | * Return the rightmost descendant of @pos. If there's no descendant, | |
3094 | * @pos is returned. This can be used during pre-order traversal to skip | |
3095 | * subtree of @pos. | |
75501a6d TH |
3096 | * |
3097 | * While this function requires RCU read locking, it doesn't require the | |
3098 | * whole traversal to be contained in a single RCU critical section. This | |
3099 | * function will return the correct rightmost descendant as long as @pos is | |
3100 | * accessible. | |
12a9d2fe TH |
3101 | */ |
3102 | struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos) | |
3103 | { | |
3104 | struct cgroup *last, *tmp; | |
3105 | ||
3106 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3107 | ||
3108 | do { | |
3109 | last = pos; | |
3110 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3111 | pos = NULL; | |
3112 | list_for_each_entry_rcu(tmp, &last->children, sibling) | |
3113 | pos = tmp; | |
3114 | } while (pos); | |
3115 | ||
3116 | return last; | |
3117 | } | |
3118 | EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant); | |
3119 | ||
574bd9f7 TH |
3120 | static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) |
3121 | { | |
3122 | struct cgroup *last; | |
3123 | ||
3124 | do { | |
3125 | last = pos; | |
3126 | pos = list_first_or_null_rcu(&pos->children, struct cgroup, | |
3127 | sibling); | |
3128 | } while (pos); | |
3129 | ||
3130 | return last; | |
3131 | } | |
3132 | ||
3133 | /** | |
3134 | * cgroup_next_descendant_post - find the next descendant for post-order walk | |
3135 | * @pos: the current position (%NULL to initiate traversal) | |
3136 | * @cgroup: cgroup whose descendants to walk | |
3137 | * | |
3138 | * To be used by cgroup_for_each_descendant_post(). Find the next | |
3139 | * descendant to visit for post-order traversal of @cgroup's descendants. | |
75501a6d TH |
3140 | * |
3141 | * While this function requires RCU read locking, it doesn't require the | |
3142 | * whole traversal to be contained in a single RCU critical section. This | |
3143 | * function will return the correct next descendant as long as both @pos | |
3144 | * and @cgroup are accessible and @pos is a descendant of @cgroup. | |
574bd9f7 TH |
3145 | */ |
3146 | struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, | |
3147 | struct cgroup *cgroup) | |
3148 | { | |
3149 | struct cgroup *next; | |
3150 | ||
3151 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3152 | ||
3153 | /* if first iteration, visit the leftmost descendant */ | |
3154 | if (!pos) { | |
3155 | next = cgroup_leftmost_descendant(cgroup); | |
3156 | return next != cgroup ? next : NULL; | |
3157 | } | |
3158 | ||
3159 | /* if there's an unvisited sibling, visit its leftmost descendant */ | |
75501a6d TH |
3160 | next = cgroup_next_sibling(pos); |
3161 | if (next) | |
574bd9f7 TH |
3162 | return cgroup_leftmost_descendant(next); |
3163 | ||
3164 | /* no sibling left, visit parent */ | |
3165 | next = pos->parent; | |
3166 | return next != cgroup ? next : NULL; | |
3167 | } | |
3168 | EXPORT_SYMBOL_GPL(cgroup_next_descendant_post); | |
3169 | ||
bd89aabc | 3170 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 3171 | __acquires(css_set_lock) |
817929ec PM |
3172 | { |
3173 | /* | |
3174 | * The first time anyone tries to iterate across a cgroup, | |
3175 | * we need to enable the list linking each css_set to its | |
3176 | * tasks, and fix up all existing tasks. | |
3177 | */ | |
31a7df01 CW |
3178 | if (!use_task_css_set_links) |
3179 | cgroup_enable_task_cg_lists(); | |
3180 | ||
817929ec | 3181 | read_lock(&css_set_lock); |
69d0206c | 3182 | it->cset_link = &cgrp->cset_links; |
bd89aabc | 3183 | cgroup_advance_iter(cgrp, it); |
817929ec PM |
3184 | } |
3185 | ||
bd89aabc | 3186 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
817929ec PM |
3187 | struct cgroup_iter *it) |
3188 | { | |
3189 | struct task_struct *res; | |
3190 | struct list_head *l = it->task; | |
69d0206c | 3191 | struct cgrp_cset_link *link; |
817929ec PM |
3192 | |
3193 | /* If the iterator cg is NULL, we have no tasks */ | |
69d0206c | 3194 | if (!it->cset_link) |
817929ec PM |
3195 | return NULL; |
3196 | res = list_entry(l, struct task_struct, cg_list); | |
3197 | /* Advance iterator to find next entry */ | |
3198 | l = l->next; | |
69d0206c TH |
3199 | link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link); |
3200 | if (l == &link->cset->tasks) { | |
817929ec PM |
3201 | /* We reached the end of this task list - move on to |
3202 | * the next cg_cgroup_link */ | |
bd89aabc | 3203 | cgroup_advance_iter(cgrp, it); |
817929ec PM |
3204 | } else { |
3205 | it->task = l; | |
3206 | } | |
3207 | return res; | |
3208 | } | |
3209 | ||
bd89aabc | 3210 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 3211 | __releases(css_set_lock) |
817929ec PM |
3212 | { |
3213 | read_unlock(&css_set_lock); | |
3214 | } | |
3215 | ||
31a7df01 CW |
3216 | static inline int started_after_time(struct task_struct *t1, |
3217 | struct timespec *time, | |
3218 | struct task_struct *t2) | |
3219 | { | |
3220 | int start_diff = timespec_compare(&t1->start_time, time); | |
3221 | if (start_diff > 0) { | |
3222 | return 1; | |
3223 | } else if (start_diff < 0) { | |
3224 | return 0; | |
3225 | } else { | |
3226 | /* | |
3227 | * Arbitrarily, if two processes started at the same | |
3228 | * time, we'll say that the lower pointer value | |
3229 | * started first. Note that t2 may have exited by now | |
3230 | * so this may not be a valid pointer any longer, but | |
3231 | * that's fine - it still serves to distinguish | |
3232 | * between two tasks started (effectively) simultaneously. | |
3233 | */ | |
3234 | return t1 > t2; | |
3235 | } | |
3236 | } | |
3237 | ||
3238 | /* | |
3239 | * This function is a callback from heap_insert() and is used to order | |
3240 | * the heap. | |
3241 | * In this case we order the heap in descending task start time. | |
3242 | */ | |
3243 | static inline int started_after(void *p1, void *p2) | |
3244 | { | |
3245 | struct task_struct *t1 = p1; | |
3246 | struct task_struct *t2 = p2; | |
3247 | return started_after_time(t1, &t2->start_time, t2); | |
3248 | } | |
3249 | ||
3250 | /** | |
3251 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
3252 | * @scan: struct cgroup_scanner containing arguments for the scan | |
3253 | * | |
3254 | * Arguments include pointers to callback functions test_task() and | |
3255 | * process_task(). | |
3256 | * Iterate through all the tasks in a cgroup, calling test_task() for each, | |
3257 | * and if it returns true, call process_task() for it also. | |
3258 | * The test_task pointer may be NULL, meaning always true (select all tasks). | |
3259 | * Effectively duplicates cgroup_iter_{start,next,end}() | |
3260 | * but does not lock css_set_lock for the call to process_task(). | |
3261 | * The struct cgroup_scanner may be embedded in any structure of the caller's | |
3262 | * creation. | |
3263 | * It is guaranteed that process_task() will act on every task that | |
3264 | * is a member of the cgroup for the duration of this call. This | |
3265 | * function may or may not call process_task() for tasks that exit | |
3266 | * or move to a different cgroup during the call, or are forked or | |
3267 | * move into the cgroup during the call. | |
3268 | * | |
3269 | * Note that test_task() may be called with locks held, and may in some | |
3270 | * situations be called multiple times for the same task, so it should | |
3271 | * be cheap. | |
3272 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been | |
3273 | * pre-allocated and will be used for heap operations (and its "gt" member will | |
3274 | * be overwritten), else a temporary heap will be used (allocation of which | |
3275 | * may cause this function to fail). | |
3276 | */ | |
3277 | int cgroup_scan_tasks(struct cgroup_scanner *scan) | |
3278 | { | |
3279 | int retval, i; | |
3280 | struct cgroup_iter it; | |
3281 | struct task_struct *p, *dropped; | |
3282 | /* Never dereference latest_task, since it's not refcounted */ | |
3283 | struct task_struct *latest_task = NULL; | |
3284 | struct ptr_heap tmp_heap; | |
3285 | struct ptr_heap *heap; | |
3286 | struct timespec latest_time = { 0, 0 }; | |
3287 | ||
3288 | if (scan->heap) { | |
3289 | /* The caller supplied our heap and pre-allocated its memory */ | |
3290 | heap = scan->heap; | |
3291 | heap->gt = &started_after; | |
3292 | } else { | |
3293 | /* We need to allocate our own heap memory */ | |
3294 | heap = &tmp_heap; | |
3295 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
3296 | if (retval) | |
3297 | /* cannot allocate the heap */ | |
3298 | return retval; | |
3299 | } | |
3300 | ||
3301 | again: | |
3302 | /* | |
3303 | * Scan tasks in the cgroup, using the scanner's "test_task" callback | |
3304 | * to determine which are of interest, and using the scanner's | |
3305 | * "process_task" callback to process any of them that need an update. | |
3306 | * Since we don't want to hold any locks during the task updates, | |
3307 | * gather tasks to be processed in a heap structure. | |
3308 | * The heap is sorted by descending task start time. | |
3309 | * If the statically-sized heap fills up, we overflow tasks that | |
3310 | * started later, and in future iterations only consider tasks that | |
3311 | * started after the latest task in the previous pass. This | |
3312 | * guarantees forward progress and that we don't miss any tasks. | |
3313 | */ | |
3314 | heap->size = 0; | |
3315 | cgroup_iter_start(scan->cg, &it); | |
3316 | while ((p = cgroup_iter_next(scan->cg, &it))) { | |
3317 | /* | |
3318 | * Only affect tasks that qualify per the caller's callback, | |
3319 | * if he provided one | |
3320 | */ | |
3321 | if (scan->test_task && !scan->test_task(p, scan)) | |
3322 | continue; | |
3323 | /* | |
3324 | * Only process tasks that started after the last task | |
3325 | * we processed | |
3326 | */ | |
3327 | if (!started_after_time(p, &latest_time, latest_task)) | |
3328 | continue; | |
3329 | dropped = heap_insert(heap, p); | |
3330 | if (dropped == NULL) { | |
3331 | /* | |
3332 | * The new task was inserted; the heap wasn't | |
3333 | * previously full | |
3334 | */ | |
3335 | get_task_struct(p); | |
3336 | } else if (dropped != p) { | |
3337 | /* | |
3338 | * The new task was inserted, and pushed out a | |
3339 | * different task | |
3340 | */ | |
3341 | get_task_struct(p); | |
3342 | put_task_struct(dropped); | |
3343 | } | |
3344 | /* | |
3345 | * Else the new task was newer than anything already in | |
3346 | * the heap and wasn't inserted | |
3347 | */ | |
3348 | } | |
3349 | cgroup_iter_end(scan->cg, &it); | |
3350 | ||
3351 | if (heap->size) { | |
3352 | for (i = 0; i < heap->size; i++) { | |
4fe91d51 | 3353 | struct task_struct *q = heap->ptrs[i]; |
31a7df01 | 3354 | if (i == 0) { |
4fe91d51 PJ |
3355 | latest_time = q->start_time; |
3356 | latest_task = q; | |
31a7df01 CW |
3357 | } |
3358 | /* Process the task per the caller's callback */ | |
4fe91d51 PJ |
3359 | scan->process_task(q, scan); |
3360 | put_task_struct(q); | |
31a7df01 CW |
3361 | } |
3362 | /* | |
3363 | * If we had to process any tasks at all, scan again | |
3364 | * in case some of them were in the middle of forking | |
3365 | * children that didn't get processed. | |
3366 | * Not the most efficient way to do it, but it avoids | |
3367 | * having to take callback_mutex in the fork path | |
3368 | */ | |
3369 | goto again; | |
3370 | } | |
3371 | if (heap == &tmp_heap) | |
3372 | heap_free(&tmp_heap); | |
3373 | return 0; | |
3374 | } | |
3375 | ||
8cc99345 TH |
3376 | static void cgroup_transfer_one_task(struct task_struct *task, |
3377 | struct cgroup_scanner *scan) | |
3378 | { | |
3379 | struct cgroup *new_cgroup = scan->data; | |
3380 | ||
47cfcd09 | 3381 | mutex_lock(&cgroup_mutex); |
8cc99345 | 3382 | cgroup_attach_task(new_cgroup, task, false); |
47cfcd09 | 3383 | mutex_unlock(&cgroup_mutex); |
8cc99345 TH |
3384 | } |
3385 | ||
3386 | /** | |
3387 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another | |
3388 | * @to: cgroup to which the tasks will be moved | |
3389 | * @from: cgroup in which the tasks currently reside | |
3390 | */ | |
3391 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) | |
3392 | { | |
3393 | struct cgroup_scanner scan; | |
3394 | ||
3395 | scan.cg = from; | |
3396 | scan.test_task = NULL; /* select all tasks in cgroup */ | |
3397 | scan.process_task = cgroup_transfer_one_task; | |
3398 | scan.heap = NULL; | |
3399 | scan.data = to; | |
3400 | ||
3401 | return cgroup_scan_tasks(&scan); | |
3402 | } | |
3403 | ||
bbcb81d0 | 3404 | /* |
102a775e | 3405 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3406 | * |
3407 | * Reading this file can return large amounts of data if a cgroup has | |
3408 | * *lots* of attached tasks. So it may need several calls to read(), | |
3409 | * but we cannot guarantee that the information we produce is correct | |
3410 | * unless we produce it entirely atomically. | |
3411 | * | |
bbcb81d0 | 3412 | */ |
bbcb81d0 | 3413 | |
24528255 LZ |
3414 | /* which pidlist file are we talking about? */ |
3415 | enum cgroup_filetype { | |
3416 | CGROUP_FILE_PROCS, | |
3417 | CGROUP_FILE_TASKS, | |
3418 | }; | |
3419 | ||
3420 | /* | |
3421 | * A pidlist is a list of pids that virtually represents the contents of one | |
3422 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3423 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3424 | * to the cgroup. | |
3425 | */ | |
3426 | struct cgroup_pidlist { | |
3427 | /* | |
3428 | * used to find which pidlist is wanted. doesn't change as long as | |
3429 | * this particular list stays in the list. | |
3430 | */ | |
3431 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3432 | /* array of xids */ | |
3433 | pid_t *list; | |
3434 | /* how many elements the above list has */ | |
3435 | int length; | |
3436 | /* how many files are using the current array */ | |
3437 | int use_count; | |
3438 | /* each of these stored in a list by its cgroup */ | |
3439 | struct list_head links; | |
3440 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3441 | struct cgroup *owner; | |
3442 | /* protects the other fields */ | |
3443 | struct rw_semaphore mutex; | |
3444 | }; | |
3445 | ||
d1d9fd33 BB |
3446 | /* |
3447 | * The following two functions "fix" the issue where there are more pids | |
3448 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3449 | * TODO: replace with a kernel-wide solution to this problem | |
3450 | */ | |
3451 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3452 | static void *pidlist_allocate(int count) | |
3453 | { | |
3454 | if (PIDLIST_TOO_LARGE(count)) | |
3455 | return vmalloc(count * sizeof(pid_t)); | |
3456 | else | |
3457 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3458 | } | |
3459 | static void pidlist_free(void *p) | |
3460 | { | |
3461 | if (is_vmalloc_addr(p)) | |
3462 | vfree(p); | |
3463 | else | |
3464 | kfree(p); | |
3465 | } | |
d1d9fd33 | 3466 | |
bbcb81d0 | 3467 | /* |
102a775e | 3468 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 3469 | * Returns the number of unique elements. |
bbcb81d0 | 3470 | */ |
6ee211ad | 3471 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 3472 | { |
102a775e | 3473 | int src, dest = 1; |
102a775e BB |
3474 | |
3475 | /* | |
3476 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3477 | * edge cases first; no work needs to be done for either | |
3478 | */ | |
3479 | if (length == 0 || length == 1) | |
3480 | return length; | |
3481 | /* src and dest walk down the list; dest counts unique elements */ | |
3482 | for (src = 1; src < length; src++) { | |
3483 | /* find next unique element */ | |
3484 | while (list[src] == list[src-1]) { | |
3485 | src++; | |
3486 | if (src == length) | |
3487 | goto after; | |
3488 | } | |
3489 | /* dest always points to where the next unique element goes */ | |
3490 | list[dest] = list[src]; | |
3491 | dest++; | |
3492 | } | |
3493 | after: | |
102a775e BB |
3494 | return dest; |
3495 | } | |
3496 | ||
3497 | static int cmppid(const void *a, const void *b) | |
3498 | { | |
3499 | return *(pid_t *)a - *(pid_t *)b; | |
3500 | } | |
3501 | ||
72a8cb30 BB |
3502 | /* |
3503 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3504 | * returns with the lock on that pidlist already held, and takes care | |
3505 | * of the use count, or returns NULL with no locks held if we're out of | |
3506 | * memory. | |
3507 | */ | |
3508 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, | |
3509 | enum cgroup_filetype type) | |
3510 | { | |
3511 | struct cgroup_pidlist *l; | |
3512 | /* don't need task_nsproxy() if we're looking at ourself */ | |
17cf22c3 | 3513 | struct pid_namespace *ns = task_active_pid_ns(current); |
b70cc5fd | 3514 | |
72a8cb30 BB |
3515 | /* |
3516 | * We can't drop the pidlist_mutex before taking the l->mutex in case | |
3517 | * the last ref-holder is trying to remove l from the list at the same | |
3518 | * time. Holding the pidlist_mutex precludes somebody taking whichever | |
3519 | * list we find out from under us - compare release_pid_array(). | |
3520 | */ | |
3521 | mutex_lock(&cgrp->pidlist_mutex); | |
3522 | list_for_each_entry(l, &cgrp->pidlists, links) { | |
3523 | if (l->key.type == type && l->key.ns == ns) { | |
72a8cb30 BB |
3524 | /* make sure l doesn't vanish out from under us */ |
3525 | down_write(&l->mutex); | |
3526 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3527 | return l; |
3528 | } | |
3529 | } | |
3530 | /* entry not found; create a new one */ | |
f4f4be2b | 3531 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
72a8cb30 BB |
3532 | if (!l) { |
3533 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3534 | return l; |
3535 | } | |
3536 | init_rwsem(&l->mutex); | |
3537 | down_write(&l->mutex); | |
3538 | l->key.type = type; | |
b70cc5fd | 3539 | l->key.ns = get_pid_ns(ns); |
72a8cb30 BB |
3540 | l->owner = cgrp; |
3541 | list_add(&l->links, &cgrp->pidlists); | |
3542 | mutex_unlock(&cgrp->pidlist_mutex); | |
3543 | return l; | |
3544 | } | |
3545 | ||
102a775e BB |
3546 | /* |
3547 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3548 | */ | |
72a8cb30 BB |
3549 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3550 | struct cgroup_pidlist **lp) | |
102a775e BB |
3551 | { |
3552 | pid_t *array; | |
3553 | int length; | |
3554 | int pid, n = 0; /* used for populating the array */ | |
817929ec PM |
3555 | struct cgroup_iter it; |
3556 | struct task_struct *tsk; | |
102a775e BB |
3557 | struct cgroup_pidlist *l; |
3558 | ||
3559 | /* | |
3560 | * If cgroup gets more users after we read count, we won't have | |
3561 | * enough space - tough. This race is indistinguishable to the | |
3562 | * caller from the case that the additional cgroup users didn't | |
3563 | * show up until sometime later on. | |
3564 | */ | |
3565 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3566 | array = pidlist_allocate(length); |
102a775e BB |
3567 | if (!array) |
3568 | return -ENOMEM; | |
3569 | /* now, populate the array */ | |
bd89aabc PM |
3570 | cgroup_iter_start(cgrp, &it); |
3571 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
102a775e | 3572 | if (unlikely(n == length)) |
817929ec | 3573 | break; |
102a775e | 3574 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3575 | if (type == CGROUP_FILE_PROCS) |
3576 | pid = task_tgid_vnr(tsk); | |
3577 | else | |
3578 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3579 | if (pid > 0) /* make sure to only use valid results */ |
3580 | array[n++] = pid; | |
817929ec | 3581 | } |
bd89aabc | 3582 | cgroup_iter_end(cgrp, &it); |
102a775e BB |
3583 | length = n; |
3584 | /* now sort & (if procs) strip out duplicates */ | |
3585 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3586 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 3587 | length = pidlist_uniq(array, length); |
72a8cb30 BB |
3588 | l = cgroup_pidlist_find(cgrp, type); |
3589 | if (!l) { | |
d1d9fd33 | 3590 | pidlist_free(array); |
72a8cb30 | 3591 | return -ENOMEM; |
102a775e | 3592 | } |
72a8cb30 | 3593 | /* store array, freeing old if necessary - lock already held */ |
d1d9fd33 | 3594 | pidlist_free(l->list); |
102a775e BB |
3595 | l->list = array; |
3596 | l->length = length; | |
3597 | l->use_count++; | |
3598 | up_write(&l->mutex); | |
72a8cb30 | 3599 | *lp = l; |
102a775e | 3600 | return 0; |
bbcb81d0 PM |
3601 | } |
3602 | ||
846c7bb0 | 3603 | /** |
a043e3b2 | 3604 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3605 | * @stats: cgroupstats to fill information into |
3606 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3607 | * been requested. | |
a043e3b2 LZ |
3608 | * |
3609 | * Build and fill cgroupstats so that taskstats can export it to user | |
3610 | * space. | |
846c7bb0 BS |
3611 | */ |
3612 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3613 | { | |
3614 | int ret = -EINVAL; | |
bd89aabc | 3615 | struct cgroup *cgrp; |
846c7bb0 BS |
3616 | struct cgroup_iter it; |
3617 | struct task_struct *tsk; | |
33d283be | 3618 | |
846c7bb0 | 3619 | /* |
33d283be LZ |
3620 | * Validate dentry by checking the superblock operations, |
3621 | * and make sure it's a directory. | |
846c7bb0 | 3622 | */ |
33d283be LZ |
3623 | if (dentry->d_sb->s_op != &cgroup_ops || |
3624 | !S_ISDIR(dentry->d_inode->i_mode)) | |
846c7bb0 BS |
3625 | goto err; |
3626 | ||
3627 | ret = 0; | |
bd89aabc | 3628 | cgrp = dentry->d_fsdata; |
846c7bb0 | 3629 | |
bd89aabc PM |
3630 | cgroup_iter_start(cgrp, &it); |
3631 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
846c7bb0 BS |
3632 | switch (tsk->state) { |
3633 | case TASK_RUNNING: | |
3634 | stats->nr_running++; | |
3635 | break; | |
3636 | case TASK_INTERRUPTIBLE: | |
3637 | stats->nr_sleeping++; | |
3638 | break; | |
3639 | case TASK_UNINTERRUPTIBLE: | |
3640 | stats->nr_uninterruptible++; | |
3641 | break; | |
3642 | case TASK_STOPPED: | |
3643 | stats->nr_stopped++; | |
3644 | break; | |
3645 | default: | |
3646 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3647 | stats->nr_io_wait++; | |
3648 | break; | |
3649 | } | |
3650 | } | |
bd89aabc | 3651 | cgroup_iter_end(cgrp, &it); |
846c7bb0 | 3652 | |
846c7bb0 BS |
3653 | err: |
3654 | return ret; | |
3655 | } | |
3656 | ||
8f3ff208 | 3657 | |
bbcb81d0 | 3658 | /* |
102a775e | 3659 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3660 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3661 | * in the cgroup->l->list array. |
bbcb81d0 | 3662 | */ |
cc31edce | 3663 | |
102a775e | 3664 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3665 | { |
cc31edce PM |
3666 | /* |
3667 | * Initially we receive a position value that corresponds to | |
3668 | * one more than the last pid shown (or 0 on the first call or | |
3669 | * after a seek to the start). Use a binary-search to find the | |
3670 | * next pid to display, if any | |
3671 | */ | |
102a775e | 3672 | struct cgroup_pidlist *l = s->private; |
cc31edce PM |
3673 | int index = 0, pid = *pos; |
3674 | int *iter; | |
3675 | ||
102a775e | 3676 | down_read(&l->mutex); |
cc31edce | 3677 | if (pid) { |
102a775e | 3678 | int end = l->length; |
20777766 | 3679 | |
cc31edce PM |
3680 | while (index < end) { |
3681 | int mid = (index + end) / 2; | |
102a775e | 3682 | if (l->list[mid] == pid) { |
cc31edce PM |
3683 | index = mid; |
3684 | break; | |
102a775e | 3685 | } else if (l->list[mid] <= pid) |
cc31edce PM |
3686 | index = mid + 1; |
3687 | else | |
3688 | end = mid; | |
3689 | } | |
3690 | } | |
3691 | /* If we're off the end of the array, we're done */ | |
102a775e | 3692 | if (index >= l->length) |
cc31edce PM |
3693 | return NULL; |
3694 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3695 | iter = l->list + index; |
cc31edce PM |
3696 | *pos = *iter; |
3697 | return iter; | |
3698 | } | |
3699 | ||
102a775e | 3700 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3701 | { |
102a775e BB |
3702 | struct cgroup_pidlist *l = s->private; |
3703 | up_read(&l->mutex); | |
cc31edce PM |
3704 | } |
3705 | ||
102a775e | 3706 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3707 | { |
102a775e BB |
3708 | struct cgroup_pidlist *l = s->private; |
3709 | pid_t *p = v; | |
3710 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3711 | /* |
3712 | * Advance to the next pid in the array. If this goes off the | |
3713 | * end, we're done | |
3714 | */ | |
3715 | p++; | |
3716 | if (p >= end) { | |
3717 | return NULL; | |
3718 | } else { | |
3719 | *pos = *p; | |
3720 | return p; | |
3721 | } | |
3722 | } | |
3723 | ||
102a775e | 3724 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3725 | { |
3726 | return seq_printf(s, "%d\n", *(int *)v); | |
3727 | } | |
bbcb81d0 | 3728 | |
102a775e BB |
3729 | /* |
3730 | * seq_operations functions for iterating on pidlists through seq_file - | |
3731 | * independent of whether it's tasks or procs | |
3732 | */ | |
3733 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3734 | .start = cgroup_pidlist_start, | |
3735 | .stop = cgroup_pidlist_stop, | |
3736 | .next = cgroup_pidlist_next, | |
3737 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3738 | }; |
3739 | ||
102a775e | 3740 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
cc31edce | 3741 | { |
72a8cb30 BB |
3742 | /* |
3743 | * the case where we're the last user of this particular pidlist will | |
3744 | * have us remove it from the cgroup's list, which entails taking the | |
3745 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> | |
3746 | * pidlist_mutex, we have to take pidlist_mutex first. | |
3747 | */ | |
3748 | mutex_lock(&l->owner->pidlist_mutex); | |
102a775e BB |
3749 | down_write(&l->mutex); |
3750 | BUG_ON(!l->use_count); | |
3751 | if (!--l->use_count) { | |
72a8cb30 BB |
3752 | /* we're the last user if refcount is 0; remove and free */ |
3753 | list_del(&l->links); | |
3754 | mutex_unlock(&l->owner->pidlist_mutex); | |
d1d9fd33 | 3755 | pidlist_free(l->list); |
72a8cb30 BB |
3756 | put_pid_ns(l->key.ns); |
3757 | up_write(&l->mutex); | |
3758 | kfree(l); | |
3759 | return; | |
cc31edce | 3760 | } |
72a8cb30 | 3761 | mutex_unlock(&l->owner->pidlist_mutex); |
102a775e | 3762 | up_write(&l->mutex); |
bbcb81d0 PM |
3763 | } |
3764 | ||
102a775e | 3765 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
cc31edce | 3766 | { |
102a775e | 3767 | struct cgroup_pidlist *l; |
cc31edce PM |
3768 | if (!(file->f_mode & FMODE_READ)) |
3769 | return 0; | |
102a775e BB |
3770 | /* |
3771 | * the seq_file will only be initialized if the file was opened for | |
3772 | * reading; hence we check if it's not null only in that case. | |
3773 | */ | |
3774 | l = ((struct seq_file *)file->private_data)->private; | |
3775 | cgroup_release_pid_array(l); | |
cc31edce PM |
3776 | return seq_release(inode, file); |
3777 | } | |
3778 | ||
102a775e | 3779 | static const struct file_operations cgroup_pidlist_operations = { |
cc31edce PM |
3780 | .read = seq_read, |
3781 | .llseek = seq_lseek, | |
3782 | .write = cgroup_file_write, | |
102a775e | 3783 | .release = cgroup_pidlist_release, |
cc31edce PM |
3784 | }; |
3785 | ||
bbcb81d0 | 3786 | /* |
102a775e BB |
3787 | * The following functions handle opens on a file that displays a pidlist |
3788 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's | |
3789 | * in the cgroup. | |
bbcb81d0 | 3790 | */ |
102a775e | 3791 | /* helper function for the two below it */ |
72a8cb30 | 3792 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
bbcb81d0 | 3793 | { |
bd89aabc | 3794 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
72a8cb30 | 3795 | struct cgroup_pidlist *l; |
cc31edce | 3796 | int retval; |
bbcb81d0 | 3797 | |
cc31edce | 3798 | /* Nothing to do for write-only files */ |
bbcb81d0 PM |
3799 | if (!(file->f_mode & FMODE_READ)) |
3800 | return 0; | |
3801 | ||
102a775e | 3802 | /* have the array populated */ |
72a8cb30 | 3803 | retval = pidlist_array_load(cgrp, type, &l); |
102a775e BB |
3804 | if (retval) |
3805 | return retval; | |
3806 | /* configure file information */ | |
3807 | file->f_op = &cgroup_pidlist_operations; | |
cc31edce | 3808 | |
102a775e | 3809 | retval = seq_open(file, &cgroup_pidlist_seq_operations); |
cc31edce | 3810 | if (retval) { |
102a775e | 3811 | cgroup_release_pid_array(l); |
cc31edce | 3812 | return retval; |
bbcb81d0 | 3813 | } |
102a775e | 3814 | ((struct seq_file *)file->private_data)->private = l; |
bbcb81d0 PM |
3815 | return 0; |
3816 | } | |
102a775e BB |
3817 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
3818 | { | |
72a8cb30 | 3819 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
102a775e BB |
3820 | } |
3821 | static int cgroup_procs_open(struct inode *unused, struct file *file) | |
3822 | { | |
72a8cb30 | 3823 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
102a775e | 3824 | } |
bbcb81d0 | 3825 | |
bd89aabc | 3826 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
81a6a5cd PM |
3827 | struct cftype *cft) |
3828 | { | |
bd89aabc | 3829 | return notify_on_release(cgrp); |
81a6a5cd PM |
3830 | } |
3831 | ||
6379c106 PM |
3832 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
3833 | struct cftype *cft, | |
3834 | u64 val) | |
3835 | { | |
3836 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); | |
3837 | if (val) | |
3838 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3839 | else | |
3840 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3841 | return 0; | |
3842 | } | |
3843 | ||
1c8158ee LZ |
3844 | /* |
3845 | * When dput() is called asynchronously, if umount has been done and | |
3846 | * then deactivate_super() in cgroup_free_fn() kills the superblock, | |
3847 | * there's a small window that vfs will see the root dentry with non-zero | |
3848 | * refcnt and trigger BUG(). | |
3849 | * | |
3850 | * That's why we hold a reference before dput() and drop it right after. | |
3851 | */ | |
3852 | static void cgroup_dput(struct cgroup *cgrp) | |
3853 | { | |
3854 | struct super_block *sb = cgrp->root->sb; | |
3855 | ||
3856 | atomic_inc(&sb->s_active); | |
3857 | dput(cgrp->dentry); | |
3858 | deactivate_super(sb); | |
3859 | } | |
3860 | ||
0dea1168 KS |
3861 | /* |
3862 | * Unregister event and free resources. | |
3863 | * | |
3864 | * Gets called from workqueue. | |
3865 | */ | |
3866 | static void cgroup_event_remove(struct work_struct *work) | |
3867 | { | |
3868 | struct cgroup_event *event = container_of(work, struct cgroup_event, | |
3869 | remove); | |
3870 | struct cgroup *cgrp = event->cgrp; | |
3871 | ||
810cbee4 LZ |
3872 | remove_wait_queue(event->wqh, &event->wait); |
3873 | ||
0dea1168 KS |
3874 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3875 | ||
810cbee4 LZ |
3876 | /* Notify userspace the event is going away. */ |
3877 | eventfd_signal(event->eventfd, 1); | |
3878 | ||
0dea1168 | 3879 | eventfd_ctx_put(event->eventfd); |
0dea1168 | 3880 | kfree(event); |
1c8158ee | 3881 | cgroup_dput(cgrp); |
0dea1168 KS |
3882 | } |
3883 | ||
3884 | /* | |
3885 | * Gets called on POLLHUP on eventfd when user closes it. | |
3886 | * | |
3887 | * Called with wqh->lock held and interrupts disabled. | |
3888 | */ | |
3889 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, | |
3890 | int sync, void *key) | |
3891 | { | |
3892 | struct cgroup_event *event = container_of(wait, | |
3893 | struct cgroup_event, wait); | |
3894 | struct cgroup *cgrp = event->cgrp; | |
3895 | unsigned long flags = (unsigned long)key; | |
3896 | ||
3897 | if (flags & POLLHUP) { | |
0dea1168 | 3898 | /* |
810cbee4 LZ |
3899 | * If the event has been detached at cgroup removal, we |
3900 | * can simply return knowing the other side will cleanup | |
3901 | * for us. | |
3902 | * | |
3903 | * We can't race against event freeing since the other | |
3904 | * side will require wqh->lock via remove_wait_queue(), | |
3905 | * which we hold. | |
0dea1168 | 3906 | */ |
810cbee4 LZ |
3907 | spin_lock(&cgrp->event_list_lock); |
3908 | if (!list_empty(&event->list)) { | |
3909 | list_del_init(&event->list); | |
3910 | /* | |
3911 | * We are in atomic context, but cgroup_event_remove() | |
3912 | * may sleep, so we have to call it in workqueue. | |
3913 | */ | |
3914 | schedule_work(&event->remove); | |
3915 | } | |
3916 | spin_unlock(&cgrp->event_list_lock); | |
0dea1168 KS |
3917 | } |
3918 | ||
3919 | return 0; | |
3920 | } | |
3921 | ||
3922 | static void cgroup_event_ptable_queue_proc(struct file *file, | |
3923 | wait_queue_head_t *wqh, poll_table *pt) | |
3924 | { | |
3925 | struct cgroup_event *event = container_of(pt, | |
3926 | struct cgroup_event, pt); | |
3927 | ||
3928 | event->wqh = wqh; | |
3929 | add_wait_queue(wqh, &event->wait); | |
3930 | } | |
3931 | ||
3932 | /* | |
3933 | * Parse input and register new cgroup event handler. | |
3934 | * | |
3935 | * Input must be in format '<event_fd> <control_fd> <args>'. | |
3936 | * Interpretation of args is defined by control file implementation. | |
3937 | */ | |
3938 | static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, | |
3939 | const char *buffer) | |
3940 | { | |
3941 | struct cgroup_event *event = NULL; | |
f169007b | 3942 | struct cgroup *cgrp_cfile; |
0dea1168 KS |
3943 | unsigned int efd, cfd; |
3944 | struct file *efile = NULL; | |
3945 | struct file *cfile = NULL; | |
3946 | char *endp; | |
3947 | int ret; | |
3948 | ||
3949 | efd = simple_strtoul(buffer, &endp, 10); | |
3950 | if (*endp != ' ') | |
3951 | return -EINVAL; | |
3952 | buffer = endp + 1; | |
3953 | ||
3954 | cfd = simple_strtoul(buffer, &endp, 10); | |
3955 | if ((*endp != ' ') && (*endp != '\0')) | |
3956 | return -EINVAL; | |
3957 | buffer = endp + 1; | |
3958 | ||
3959 | event = kzalloc(sizeof(*event), GFP_KERNEL); | |
3960 | if (!event) | |
3961 | return -ENOMEM; | |
3962 | event->cgrp = cgrp; | |
3963 | INIT_LIST_HEAD(&event->list); | |
3964 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); | |
3965 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); | |
3966 | INIT_WORK(&event->remove, cgroup_event_remove); | |
3967 | ||
3968 | efile = eventfd_fget(efd); | |
3969 | if (IS_ERR(efile)) { | |
3970 | ret = PTR_ERR(efile); | |
3971 | goto fail; | |
3972 | } | |
3973 | ||
3974 | event->eventfd = eventfd_ctx_fileget(efile); | |
3975 | if (IS_ERR(event->eventfd)) { | |
3976 | ret = PTR_ERR(event->eventfd); | |
3977 | goto fail; | |
3978 | } | |
3979 | ||
3980 | cfile = fget(cfd); | |
3981 | if (!cfile) { | |
3982 | ret = -EBADF; | |
3983 | goto fail; | |
3984 | } | |
3985 | ||
3986 | /* the process need read permission on control file */ | |
3bfa784a | 3987 | /* AV: shouldn't we check that it's been opened for read instead? */ |
496ad9aa | 3988 | ret = inode_permission(file_inode(cfile), MAY_READ); |
0dea1168 KS |
3989 | if (ret < 0) |
3990 | goto fail; | |
3991 | ||
3992 | event->cft = __file_cft(cfile); | |
3993 | if (IS_ERR(event->cft)) { | |
3994 | ret = PTR_ERR(event->cft); | |
3995 | goto fail; | |
3996 | } | |
3997 | ||
f169007b LZ |
3998 | /* |
3999 | * The file to be monitored must be in the same cgroup as | |
4000 | * cgroup.event_control is. | |
4001 | */ | |
4002 | cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); | |
4003 | if (cgrp_cfile != cgrp) { | |
4004 | ret = -EINVAL; | |
4005 | goto fail; | |
4006 | } | |
4007 | ||
0dea1168 KS |
4008 | if (!event->cft->register_event || !event->cft->unregister_event) { |
4009 | ret = -EINVAL; | |
4010 | goto fail; | |
4011 | } | |
4012 | ||
4013 | ret = event->cft->register_event(cgrp, event->cft, | |
4014 | event->eventfd, buffer); | |
4015 | if (ret) | |
4016 | goto fail; | |
4017 | ||
7ef70e48 | 4018 | efile->f_op->poll(efile, &event->pt); |
0dea1168 | 4019 | |
a0a4db54 KS |
4020 | /* |
4021 | * Events should be removed after rmdir of cgroup directory, but before | |
4022 | * destroying subsystem state objects. Let's take reference to cgroup | |
4023 | * directory dentry to do that. | |
4024 | */ | |
4025 | dget(cgrp->dentry); | |
4026 | ||
0dea1168 KS |
4027 | spin_lock(&cgrp->event_list_lock); |
4028 | list_add(&event->list, &cgrp->event_list); | |
4029 | spin_unlock(&cgrp->event_list_lock); | |
4030 | ||
4031 | fput(cfile); | |
4032 | fput(efile); | |
4033 | ||
4034 | return 0; | |
4035 | ||
4036 | fail: | |
4037 | if (cfile) | |
4038 | fput(cfile); | |
4039 | ||
4040 | if (event && event->eventfd && !IS_ERR(event->eventfd)) | |
4041 | eventfd_ctx_put(event->eventfd); | |
4042 | ||
4043 | if (!IS_ERR_OR_NULL(efile)) | |
4044 | fput(efile); | |
4045 | ||
4046 | kfree(event); | |
4047 | ||
4048 | return ret; | |
4049 | } | |
4050 | ||
97978e6d DL |
4051 | static u64 cgroup_clone_children_read(struct cgroup *cgrp, |
4052 | struct cftype *cft) | |
4053 | { | |
2260e7fc | 4054 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
97978e6d DL |
4055 | } |
4056 | ||
4057 | static int cgroup_clone_children_write(struct cgroup *cgrp, | |
4058 | struct cftype *cft, | |
4059 | u64 val) | |
4060 | { | |
4061 | if (val) | |
2260e7fc | 4062 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
97978e6d | 4063 | else |
2260e7fc | 4064 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
97978e6d DL |
4065 | return 0; |
4066 | } | |
4067 | ||
d5c56ced | 4068 | static struct cftype cgroup_base_files[] = { |
81a6a5cd | 4069 | { |
d5c56ced | 4070 | .name = "cgroup.procs", |
102a775e | 4071 | .open = cgroup_procs_open, |
74a1166d | 4072 | .write_u64 = cgroup_procs_write, |
102a775e | 4073 | .release = cgroup_pidlist_release, |
74a1166d | 4074 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 4075 | }, |
81a6a5cd | 4076 | { |
d5c56ced | 4077 | .name = "cgroup.event_control", |
0dea1168 KS |
4078 | .write_string = cgroup_write_event_control, |
4079 | .mode = S_IWUGO, | |
4080 | }, | |
97978e6d DL |
4081 | { |
4082 | .name = "cgroup.clone_children", | |
873fe09e | 4083 | .flags = CFTYPE_INSANE, |
97978e6d DL |
4084 | .read_u64 = cgroup_clone_children_read, |
4085 | .write_u64 = cgroup_clone_children_write, | |
4086 | }, | |
873fe09e TH |
4087 | { |
4088 | .name = "cgroup.sane_behavior", | |
4089 | .flags = CFTYPE_ONLY_ON_ROOT, | |
4090 | .read_seq_string = cgroup_sane_behavior_show, | |
4091 | }, | |
d5c56ced TH |
4092 | |
4093 | /* | |
4094 | * Historical crazy stuff. These don't have "cgroup." prefix and | |
4095 | * don't exist if sane_behavior. If you're depending on these, be | |
4096 | * prepared to be burned. | |
4097 | */ | |
4098 | { | |
4099 | .name = "tasks", | |
4100 | .flags = CFTYPE_INSANE, /* use "procs" instead */ | |
4101 | .open = cgroup_tasks_open, | |
4102 | .write_u64 = cgroup_tasks_write, | |
4103 | .release = cgroup_pidlist_release, | |
4104 | .mode = S_IRUGO | S_IWUSR, | |
4105 | }, | |
4106 | { | |
4107 | .name = "notify_on_release", | |
4108 | .flags = CFTYPE_INSANE, | |
4109 | .read_u64 = cgroup_read_notify_on_release, | |
4110 | .write_u64 = cgroup_write_notify_on_release, | |
4111 | }, | |
6e6ff25b TH |
4112 | { |
4113 | .name = "release_agent", | |
cc5943a7 | 4114 | .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT, |
6e6ff25b TH |
4115 | .read_seq_string = cgroup_release_agent_show, |
4116 | .write_string = cgroup_release_agent_write, | |
4117 | .max_write_len = PATH_MAX, | |
4118 | }, | |
db0416b6 | 4119 | { } /* terminate */ |
bbcb81d0 PM |
4120 | }; |
4121 | ||
13af07df AR |
4122 | /** |
4123 | * cgroup_populate_dir - selectively creation of files in a directory | |
4124 | * @cgrp: target cgroup | |
4125 | * @base_files: true if the base files should be added | |
4126 | * @subsys_mask: mask of the subsystem ids whose files should be added | |
4127 | */ | |
4128 | static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, | |
4129 | unsigned long subsys_mask) | |
ddbcc7e8 PM |
4130 | { |
4131 | int err; | |
4132 | struct cgroup_subsys *ss; | |
4133 | ||
13af07df | 4134 | if (base_files) { |
d5c56ced | 4135 | err = cgroup_addrm_files(cgrp, NULL, cgroup_base_files, true); |
13af07df AR |
4136 | if (err < 0) |
4137 | return err; | |
4138 | } | |
bbcb81d0 | 4139 | |
8e3f6541 | 4140 | /* process cftsets of each subsystem */ |
bd89aabc | 4141 | for_each_subsys(cgrp->root, ss) { |
8e3f6541 | 4142 | struct cftype_set *set; |
13af07df AR |
4143 | if (!test_bit(ss->subsys_id, &subsys_mask)) |
4144 | continue; | |
8e3f6541 | 4145 | |
db0416b6 | 4146 | list_for_each_entry(set, &ss->cftsets, node) |
79578621 | 4147 | cgroup_addrm_files(cgrp, ss, set->cfts, true); |
ddbcc7e8 | 4148 | } |
8e3f6541 | 4149 | |
38460b48 KH |
4150 | /* This cgroup is ready now */ |
4151 | for_each_subsys(cgrp->root, ss) { | |
4152 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
4153 | /* | |
4154 | * Update id->css pointer and make this css visible from | |
4155 | * CSS ID functions. This pointer will be dereferened | |
4156 | * from RCU-read-side without locks. | |
4157 | */ | |
4158 | if (css->id) | |
4159 | rcu_assign_pointer(css->id->css, css); | |
4160 | } | |
ddbcc7e8 PM |
4161 | |
4162 | return 0; | |
4163 | } | |
4164 | ||
48ddbe19 TH |
4165 | static void css_dput_fn(struct work_struct *work) |
4166 | { | |
4167 | struct cgroup_subsys_state *css = | |
4168 | container_of(work, struct cgroup_subsys_state, dput_work); | |
4169 | ||
1c8158ee | 4170 | cgroup_dput(css->cgroup); |
48ddbe19 TH |
4171 | } |
4172 | ||
d3daf28d TH |
4173 | static void css_release(struct percpu_ref *ref) |
4174 | { | |
4175 | struct cgroup_subsys_state *css = | |
4176 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4177 | ||
4178 | schedule_work(&css->dput_work); | |
4179 | } | |
4180 | ||
ddbcc7e8 PM |
4181 | static void init_cgroup_css(struct cgroup_subsys_state *css, |
4182 | struct cgroup_subsys *ss, | |
bd89aabc | 4183 | struct cgroup *cgrp) |
ddbcc7e8 | 4184 | { |
bd89aabc | 4185 | css->cgroup = cgrp; |
ddbcc7e8 | 4186 | css->flags = 0; |
38460b48 | 4187 | css->id = NULL; |
bd89aabc | 4188 | if (cgrp == dummytop) |
38b53aba | 4189 | css->flags |= CSS_ROOT; |
bd89aabc PM |
4190 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
4191 | cgrp->subsys[ss->subsys_id] = css; | |
48ddbe19 TH |
4192 | |
4193 | /* | |
ed957793 TH |
4194 | * css holds an extra ref to @cgrp->dentry which is put on the last |
4195 | * css_put(). dput() requires process context, which css_put() may | |
4196 | * be called without. @css->dput_work will be used to invoke | |
4197 | * dput() asynchronously from css_put(). | |
48ddbe19 TH |
4198 | */ |
4199 | INIT_WORK(&css->dput_work, css_dput_fn); | |
ddbcc7e8 PM |
4200 | } |
4201 | ||
b1929db4 TH |
4202 | /* invoke ->post_create() on a new CSS and mark it online if successful */ |
4203 | static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) | |
a31f2d3f | 4204 | { |
b1929db4 TH |
4205 | int ret = 0; |
4206 | ||
a31f2d3f TH |
4207 | lockdep_assert_held(&cgroup_mutex); |
4208 | ||
92fb9748 TH |
4209 | if (ss->css_online) |
4210 | ret = ss->css_online(cgrp); | |
b1929db4 TH |
4211 | if (!ret) |
4212 | cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE; | |
4213 | return ret; | |
a31f2d3f TH |
4214 | } |
4215 | ||
4216 | /* if the CSS is online, invoke ->pre_destory() on it and mark it offline */ | |
4217 | static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp) | |
4218 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
4219 | { | |
4220 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
4221 | ||
4222 | lockdep_assert_held(&cgroup_mutex); | |
4223 | ||
4224 | if (!(css->flags & CSS_ONLINE)) | |
4225 | return; | |
4226 | ||
d7eeac19 | 4227 | if (ss->css_offline) |
92fb9748 | 4228 | ss->css_offline(cgrp); |
a31f2d3f TH |
4229 | |
4230 | cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE; | |
4231 | } | |
4232 | ||
ddbcc7e8 | 4233 | /* |
a043e3b2 LZ |
4234 | * cgroup_create - create a cgroup |
4235 | * @parent: cgroup that will be parent of the new cgroup | |
4236 | * @dentry: dentry of the new cgroup | |
4237 | * @mode: mode to set on new inode | |
ddbcc7e8 | 4238 | * |
a043e3b2 | 4239 | * Must be called with the mutex on the parent inode held |
ddbcc7e8 | 4240 | */ |
ddbcc7e8 | 4241 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
a5e7ed32 | 4242 | umode_t mode) |
ddbcc7e8 | 4243 | { |
bd89aabc | 4244 | struct cgroup *cgrp; |
65dff759 | 4245 | struct cgroup_name *name; |
ddbcc7e8 PM |
4246 | struct cgroupfs_root *root = parent->root; |
4247 | int err = 0; | |
4248 | struct cgroup_subsys *ss; | |
4249 | struct super_block *sb = root->sb; | |
4250 | ||
0a950f65 | 4251 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc PM |
4252 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
4253 | if (!cgrp) | |
ddbcc7e8 PM |
4254 | return -ENOMEM; |
4255 | ||
65dff759 LZ |
4256 | name = cgroup_alloc_name(dentry); |
4257 | if (!name) | |
4258 | goto err_free_cgrp; | |
4259 | rcu_assign_pointer(cgrp->name, name); | |
4260 | ||
0a950f65 TH |
4261 | cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL); |
4262 | if (cgrp->id < 0) | |
65dff759 | 4263 | goto err_free_name; |
0a950f65 | 4264 | |
976c06bc TH |
4265 | /* |
4266 | * Only live parents can have children. Note that the liveliness | |
4267 | * check isn't strictly necessary because cgroup_mkdir() and | |
4268 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it | |
4269 | * anyway so that locking is contained inside cgroup proper and we | |
4270 | * don't get nasty surprises if we ever grow another caller. | |
4271 | */ | |
4272 | if (!cgroup_lock_live_group(parent)) { | |
4273 | err = -ENODEV; | |
0a950f65 | 4274 | goto err_free_id; |
976c06bc TH |
4275 | } |
4276 | ||
ddbcc7e8 PM |
4277 | /* Grab a reference on the superblock so the hierarchy doesn't |
4278 | * get deleted on unmount if there are child cgroups. This | |
4279 | * can be done outside cgroup_mutex, since the sb can't | |
4280 | * disappear while someone has an open control file on the | |
4281 | * fs */ | |
4282 | atomic_inc(&sb->s_active); | |
4283 | ||
cc31edce | 4284 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4285 | |
fe1c06ca LZ |
4286 | dentry->d_fsdata = cgrp; |
4287 | cgrp->dentry = dentry; | |
4288 | ||
bd89aabc PM |
4289 | cgrp->parent = parent; |
4290 | cgrp->root = parent->root; | |
ddbcc7e8 | 4291 | |
b6abdb0e LZ |
4292 | if (notify_on_release(parent)) |
4293 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4294 | ||
2260e7fc TH |
4295 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4296 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4297 | |
ddbcc7e8 | 4298 | for_each_subsys(root, ss) { |
8c7f6edb | 4299 | struct cgroup_subsys_state *css; |
4528fd05 | 4300 | |
92fb9748 | 4301 | css = ss->css_alloc(cgrp); |
ddbcc7e8 PM |
4302 | if (IS_ERR(css)) { |
4303 | err = PTR_ERR(css); | |
4b8b47eb | 4304 | goto err_free_all; |
ddbcc7e8 | 4305 | } |
d3daf28d TH |
4306 | |
4307 | err = percpu_ref_init(&css->refcnt, css_release); | |
4308 | if (err) | |
4309 | goto err_free_all; | |
4310 | ||
bd89aabc | 4311 | init_cgroup_css(css, ss, cgrp); |
d3daf28d | 4312 | |
4528fd05 LZ |
4313 | if (ss->use_id) { |
4314 | err = alloc_css_id(ss, parent, cgrp); | |
4315 | if (err) | |
4b8b47eb | 4316 | goto err_free_all; |
4528fd05 | 4317 | } |
ddbcc7e8 PM |
4318 | } |
4319 | ||
4e139afc TH |
4320 | /* |
4321 | * Create directory. cgroup_create_file() returns with the new | |
4322 | * directory locked on success so that it can be populated without | |
4323 | * dropping cgroup_mutex. | |
4324 | */ | |
28fd6f30 | 4325 | err = cgroup_create_file(dentry, S_IFDIR | mode, sb); |
ddbcc7e8 | 4326 | if (err < 0) |
4b8b47eb | 4327 | goto err_free_all; |
4e139afc | 4328 | lockdep_assert_held(&dentry->d_inode->i_mutex); |
ddbcc7e8 | 4329 | |
794611a1 | 4330 | cgrp->serial_nr = atomic64_inc_return(&cgroup_serial_nr_cursor); |
53fa5261 | 4331 | |
4e139afc | 4332 | /* allocation complete, commit to creation */ |
4e139afc TH |
4333 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); |
4334 | root->number_of_cgroups++; | |
28fd6f30 | 4335 | |
b1929db4 TH |
4336 | /* each css holds a ref to the cgroup's dentry */ |
4337 | for_each_subsys(root, ss) | |
ed957793 | 4338 | dget(dentry); |
48ddbe19 | 4339 | |
415cf07a LZ |
4340 | /* hold a ref to the parent's dentry */ |
4341 | dget(parent->dentry); | |
4342 | ||
b1929db4 TH |
4343 | /* creation succeeded, notify subsystems */ |
4344 | for_each_subsys(root, ss) { | |
4345 | err = online_css(ss, cgrp); | |
4346 | if (err) | |
4347 | goto err_destroy; | |
1f869e87 GC |
4348 | |
4349 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && | |
4350 | parent->parent) { | |
4351 | pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", | |
4352 | current->comm, current->pid, ss->name); | |
4353 | if (!strcmp(ss->name, "memory")) | |
4354 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); | |
4355 | ss->warned_broken_hierarchy = true; | |
4356 | } | |
a8638030 TH |
4357 | } |
4358 | ||
a1a71b45 | 4359 | err = cgroup_populate_dir(cgrp, true, root->subsys_mask); |
4b8b47eb TH |
4360 | if (err) |
4361 | goto err_destroy; | |
ddbcc7e8 PM |
4362 | |
4363 | mutex_unlock(&cgroup_mutex); | |
bd89aabc | 4364 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
4365 | |
4366 | return 0; | |
4367 | ||
4b8b47eb | 4368 | err_free_all: |
ddbcc7e8 | 4369 | for_each_subsys(root, ss) { |
d3daf28d TH |
4370 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
4371 | ||
4372 | if (css) { | |
4373 | percpu_ref_cancel_init(&css->refcnt); | |
92fb9748 | 4374 | ss->css_free(cgrp); |
d3daf28d | 4375 | } |
ddbcc7e8 | 4376 | } |
ddbcc7e8 | 4377 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
4378 | /* Release the reference count that we took on the superblock */ |
4379 | deactivate_super(sb); | |
0a950f65 TH |
4380 | err_free_id: |
4381 | ida_simple_remove(&root->cgroup_ida, cgrp->id); | |
65dff759 LZ |
4382 | err_free_name: |
4383 | kfree(rcu_dereference_raw(cgrp->name)); | |
4b8b47eb | 4384 | err_free_cgrp: |
bd89aabc | 4385 | kfree(cgrp); |
ddbcc7e8 | 4386 | return err; |
4b8b47eb TH |
4387 | |
4388 | err_destroy: | |
4389 | cgroup_destroy_locked(cgrp); | |
4390 | mutex_unlock(&cgroup_mutex); | |
4391 | mutex_unlock(&dentry->d_inode->i_mutex); | |
4392 | return err; | |
ddbcc7e8 PM |
4393 | } |
4394 | ||
18bb1db3 | 4395 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
ddbcc7e8 PM |
4396 | { |
4397 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
4398 | ||
4399 | /* the vfs holds inode->i_mutex already */ | |
4400 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
4401 | } | |
4402 | ||
d3daf28d TH |
4403 | static void cgroup_css_killed(struct cgroup *cgrp) |
4404 | { | |
4405 | if (!atomic_dec_and_test(&cgrp->css_kill_cnt)) | |
4406 | return; | |
4407 | ||
4408 | /* percpu ref's of all css's are killed, kick off the next step */ | |
4409 | INIT_WORK(&cgrp->destroy_work, cgroup_offline_fn); | |
4410 | schedule_work(&cgrp->destroy_work); | |
4411 | } | |
4412 | ||
4413 | static void css_ref_killed_fn(struct percpu_ref *ref) | |
4414 | { | |
4415 | struct cgroup_subsys_state *css = | |
4416 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4417 | ||
4418 | cgroup_css_killed(css->cgroup); | |
4419 | } | |
4420 | ||
4421 | /** | |
4422 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
4423 | * @cgrp: cgroup to be destroyed | |
4424 | * | |
4425 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
4426 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
4427 | * guarantee that css_tryget() won't succeed by the time ->css_offline() is | |
4428 | * invoked. To satisfy all the requirements, destruction is implemented in | |
4429 | * the following two steps. | |
4430 | * | |
4431 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
4432 | * userland visible parts and start killing the percpu refcnts of | |
4433 | * css's. Set up so that the next stage will be kicked off once all | |
4434 | * the percpu refcnts are confirmed to be killed. | |
4435 | * | |
4436 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
4437 | * rest of destruction. Once all cgroup references are gone, the | |
4438 | * cgroup is RCU-freed. | |
4439 | * | |
4440 | * This function implements s1. After this step, @cgrp is gone as far as | |
4441 | * the userland is concerned and a new cgroup with the same name may be | |
4442 | * created. As cgroup doesn't care about the names internally, this | |
4443 | * doesn't cause any problem. | |
4444 | */ | |
42809dd4 TH |
4445 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
4446 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 4447 | { |
42809dd4 | 4448 | struct dentry *d = cgrp->dentry; |
4ab78683 | 4449 | struct cgroup_event *event, *tmp; |
ed957793 | 4450 | struct cgroup_subsys *ss; |
ddd69148 | 4451 | bool empty; |
ddbcc7e8 | 4452 | |
42809dd4 TH |
4453 | lockdep_assert_held(&d->d_inode->i_mutex); |
4454 | lockdep_assert_held(&cgroup_mutex); | |
4455 | ||
ddd69148 | 4456 | /* |
6f3d828f TH |
4457 | * css_set_lock synchronizes access to ->cset_links and prevents |
4458 | * @cgrp from being removed while __put_css_set() is in progress. | |
ddd69148 TH |
4459 | */ |
4460 | read_lock(&css_set_lock); | |
6f3d828f | 4461 | empty = list_empty(&cgrp->cset_links) && list_empty(&cgrp->children); |
ddd69148 TH |
4462 | read_unlock(&css_set_lock); |
4463 | if (!empty) | |
ddbcc7e8 | 4464 | return -EBUSY; |
a043e3b2 | 4465 | |
88703267 | 4466 | /* |
d3daf28d TH |
4467 | * Block new css_tryget() by killing css refcnts. cgroup core |
4468 | * guarantees that, by the time ->css_offline() is invoked, no new | |
4469 | * css reference will be given out via css_tryget(). We can't | |
4470 | * simply call percpu_ref_kill() and proceed to offlining css's | |
4471 | * because percpu_ref_kill() doesn't guarantee that the ref is seen | |
4472 | * as killed on all CPUs on return. | |
4473 | * | |
4474 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
4475 | * css is confirmed to be seen as killed on all CPUs. The | |
4476 | * notification callback keeps track of the number of css's to be | |
4477 | * killed and schedules cgroup_offline_fn() to perform the rest of | |
4478 | * destruction once the percpu refs of all css's are confirmed to | |
4479 | * be killed. | |
88703267 | 4480 | */ |
d3daf28d | 4481 | atomic_set(&cgrp->css_kill_cnt, 1); |
ed957793 TH |
4482 | for_each_subsys(cgrp->root, ss) { |
4483 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
88703267 | 4484 | |
d3daf28d TH |
4485 | /* |
4486 | * Killing would put the base ref, but we need to keep it | |
4487 | * alive until after ->css_offline. | |
4488 | */ | |
4489 | percpu_ref_get(&css->refcnt); | |
4490 | ||
4491 | atomic_inc(&cgrp->css_kill_cnt); | |
4492 | percpu_ref_kill_and_confirm(&css->refcnt, css_ref_killed_fn); | |
88703267 | 4493 | } |
d3daf28d | 4494 | cgroup_css_killed(cgrp); |
455050d2 TH |
4495 | |
4496 | /* | |
4497 | * Mark @cgrp dead. This prevents further task migration and child | |
4498 | * creation by disabling cgroup_lock_live_group(). Note that | |
4499 | * CGRP_DEAD assertion is depended upon by cgroup_next_sibling() to | |
4500 | * resume iteration after dropping RCU read lock. See | |
4501 | * cgroup_next_sibling() for details. | |
4502 | */ | |
54766d4a | 4503 | set_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 | 4504 | |
455050d2 TH |
4505 | /* CGRP_DEAD is set, remove from ->release_list for the last time */ |
4506 | raw_spin_lock(&release_list_lock); | |
4507 | if (!list_empty(&cgrp->release_list)) | |
4508 | list_del_init(&cgrp->release_list); | |
4509 | raw_spin_unlock(&release_list_lock); | |
4510 | ||
4511 | /* | |
4512 | * Remove @cgrp directory. The removal puts the base ref but we | |
4513 | * aren't quite done with @cgrp yet, so hold onto it. | |
4514 | */ | |
4515 | dget(d); | |
4516 | cgroup_d_remove_dir(d); | |
4517 | ||
4518 | /* | |
4519 | * Unregister events and notify userspace. | |
4520 | * Notify userspace about cgroup removing only after rmdir of cgroup | |
4521 | * directory to avoid race between userspace and kernelspace. | |
4522 | */ | |
4523 | spin_lock(&cgrp->event_list_lock); | |
4524 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { | |
4525 | list_del_init(&event->list); | |
4526 | schedule_work(&event->remove); | |
4527 | } | |
4528 | spin_unlock(&cgrp->event_list_lock); | |
4529 | ||
ea15f8cc TH |
4530 | return 0; |
4531 | }; | |
4532 | ||
d3daf28d TH |
4533 | /** |
4534 | * cgroup_offline_fn - the second step of cgroup destruction | |
4535 | * @work: cgroup->destroy_free_work | |
4536 | * | |
4537 | * This function is invoked from a work item for a cgroup which is being | |
4538 | * destroyed after the percpu refcnts of all css's are guaranteed to be | |
4539 | * seen as killed on all CPUs, and performs the rest of destruction. This | |
4540 | * is the second step of destruction described in the comment above | |
4541 | * cgroup_destroy_locked(). | |
4542 | */ | |
ea15f8cc TH |
4543 | static void cgroup_offline_fn(struct work_struct *work) |
4544 | { | |
4545 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); | |
4546 | struct cgroup *parent = cgrp->parent; | |
4547 | struct dentry *d = cgrp->dentry; | |
4548 | struct cgroup_subsys *ss; | |
4549 | ||
4550 | mutex_lock(&cgroup_mutex); | |
4551 | ||
d3daf28d TH |
4552 | /* |
4553 | * css_tryget() is guaranteed to fail now. Tell subsystems to | |
4554 | * initate destruction. | |
4555 | */ | |
1a90dd50 | 4556 | for_each_subsys(cgrp->root, ss) |
a31f2d3f | 4557 | offline_css(ss, cgrp); |
ed957793 TH |
4558 | |
4559 | /* | |
d3daf28d TH |
4560 | * Put the css refs from cgroup_destroy_locked(). Each css holds |
4561 | * an extra reference to the cgroup's dentry and cgroup removal | |
4562 | * proceeds regardless of css refs. On the last put of each css, | |
4563 | * whenever that may be, the extra dentry ref is put so that dentry | |
4564 | * destruction happens only after all css's are released. | |
ed957793 | 4565 | */ |
e9316080 TH |
4566 | for_each_subsys(cgrp->root, ss) |
4567 | css_put(cgrp->subsys[ss->subsys_id]); | |
ddbcc7e8 | 4568 | |
999cd8a4 | 4569 | /* delete this cgroup from parent->children */ |
eb6fd504 | 4570 | list_del_rcu(&cgrp->sibling); |
b0ca5a84 | 4571 | |
ddbcc7e8 | 4572 | dput(d); |
ddbcc7e8 | 4573 | |
bd89aabc | 4574 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd PM |
4575 | check_for_release(parent); |
4576 | ||
ea15f8cc | 4577 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
4578 | } |
4579 | ||
42809dd4 TH |
4580 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
4581 | { | |
4582 | int ret; | |
4583 | ||
4584 | mutex_lock(&cgroup_mutex); | |
4585 | ret = cgroup_destroy_locked(dentry->d_fsdata); | |
4586 | mutex_unlock(&cgroup_mutex); | |
4587 | ||
4588 | return ret; | |
4589 | } | |
4590 | ||
8e3f6541 TH |
4591 | static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) |
4592 | { | |
4593 | INIT_LIST_HEAD(&ss->cftsets); | |
4594 | ||
4595 | /* | |
4596 | * base_cftset is embedded in subsys itself, no need to worry about | |
4597 | * deregistration. | |
4598 | */ | |
4599 | if (ss->base_cftypes) { | |
4600 | ss->base_cftset.cfts = ss->base_cftypes; | |
4601 | list_add_tail(&ss->base_cftset.node, &ss->cftsets); | |
4602 | } | |
4603 | } | |
4604 | ||
06a11920 | 4605 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 4606 | { |
ddbcc7e8 | 4607 | struct cgroup_subsys_state *css; |
cfe36bde DC |
4608 | |
4609 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 4610 | |
648bb56d TH |
4611 | mutex_lock(&cgroup_mutex); |
4612 | ||
8e3f6541 TH |
4613 | /* init base cftset */ |
4614 | cgroup_init_cftsets(ss); | |
4615 | ||
ddbcc7e8 | 4616 | /* Create the top cgroup state for this subsystem */ |
33a68ac1 | 4617 | list_add(&ss->sibling, &rootnode.subsys_list); |
ddbcc7e8 | 4618 | ss->root = &rootnode; |
92fb9748 | 4619 | css = ss->css_alloc(dummytop); |
ddbcc7e8 PM |
4620 | /* We don't handle early failures gracefully */ |
4621 | BUG_ON(IS_ERR(css)); | |
4622 | init_cgroup_css(css, ss, dummytop); | |
4623 | ||
e8d55fde | 4624 | /* Update the init_css_set to contain a subsys |
817929ec | 4625 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
4626 | * newly registered, all tasks and hence the |
4627 | * init_css_set is in the subsystem's top cgroup. */ | |
b48c6a80 | 4628 | init_css_set.subsys[ss->subsys_id] = css; |
ddbcc7e8 PM |
4629 | |
4630 | need_forkexit_callback |= ss->fork || ss->exit; | |
4631 | ||
e8d55fde LZ |
4632 | /* At system boot, before all subsystems have been |
4633 | * registered, no tasks have been forked, so we don't | |
4634 | * need to invoke fork callbacks here. */ | |
4635 | BUG_ON(!list_empty(&init_task.tasks)); | |
4636 | ||
b1929db4 | 4637 | BUG_ON(online_css(ss, dummytop)); |
a8638030 | 4638 | |
648bb56d TH |
4639 | mutex_unlock(&cgroup_mutex); |
4640 | ||
e6a1105b BB |
4641 | /* this function shouldn't be used with modular subsystems, since they |
4642 | * need to register a subsys_id, among other things */ | |
4643 | BUG_ON(ss->module); | |
4644 | } | |
4645 | ||
4646 | /** | |
4647 | * cgroup_load_subsys: load and register a modular subsystem at runtime | |
4648 | * @ss: the subsystem to load | |
4649 | * | |
4650 | * This function should be called in a modular subsystem's initcall. If the | |
88393161 | 4651 | * subsystem is built as a module, it will be assigned a new subsys_id and set |
e6a1105b BB |
4652 | * up for use. If the subsystem is built-in anyway, work is delegated to the |
4653 | * simpler cgroup_init_subsys. | |
4654 | */ | |
4655 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) | |
4656 | { | |
e6a1105b | 4657 | struct cgroup_subsys_state *css; |
d19e19de | 4658 | int i, ret; |
b67bfe0d | 4659 | struct hlist_node *tmp; |
5abb8855 | 4660 | struct css_set *cset; |
0ac801fe | 4661 | unsigned long key; |
e6a1105b BB |
4662 | |
4663 | /* check name and function validity */ | |
4664 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || | |
92fb9748 | 4665 | ss->css_alloc == NULL || ss->css_free == NULL) |
e6a1105b BB |
4666 | return -EINVAL; |
4667 | ||
4668 | /* | |
4669 | * we don't support callbacks in modular subsystems. this check is | |
4670 | * before the ss->module check for consistency; a subsystem that could | |
4671 | * be a module should still have no callbacks even if the user isn't | |
4672 | * compiling it as one. | |
4673 | */ | |
4674 | if (ss->fork || ss->exit) | |
4675 | return -EINVAL; | |
4676 | ||
4677 | /* | |
4678 | * an optionally modular subsystem is built-in: we want to do nothing, | |
4679 | * since cgroup_init_subsys will have already taken care of it. | |
4680 | */ | |
4681 | if (ss->module == NULL) { | |
be45c900 | 4682 | /* a sanity check */ |
e6a1105b BB |
4683 | BUG_ON(subsys[ss->subsys_id] != ss); |
4684 | return 0; | |
4685 | } | |
4686 | ||
8e3f6541 TH |
4687 | /* init base cftset */ |
4688 | cgroup_init_cftsets(ss); | |
4689 | ||
e6a1105b | 4690 | mutex_lock(&cgroup_mutex); |
8a8e04df | 4691 | subsys[ss->subsys_id] = ss; |
e6a1105b BB |
4692 | |
4693 | /* | |
92fb9748 TH |
4694 | * no ss->css_alloc seems to need anything important in the ss |
4695 | * struct, so this can happen first (i.e. before the rootnode | |
4696 | * attachment). | |
e6a1105b | 4697 | */ |
92fb9748 | 4698 | css = ss->css_alloc(dummytop); |
e6a1105b BB |
4699 | if (IS_ERR(css)) { |
4700 | /* failure case - need to deassign the subsys[] slot. */ | |
8a8e04df | 4701 | subsys[ss->subsys_id] = NULL; |
e6a1105b BB |
4702 | mutex_unlock(&cgroup_mutex); |
4703 | return PTR_ERR(css); | |
4704 | } | |
4705 | ||
4706 | list_add(&ss->sibling, &rootnode.subsys_list); | |
4707 | ss->root = &rootnode; | |
4708 | ||
4709 | /* our new subsystem will be attached to the dummy hierarchy. */ | |
4710 | init_cgroup_css(css, ss, dummytop); | |
4711 | /* init_idr must be after init_cgroup_css because it sets css->id. */ | |
4712 | if (ss->use_id) { | |
d19e19de TH |
4713 | ret = cgroup_init_idr(ss, css); |
4714 | if (ret) | |
4715 | goto err_unload; | |
e6a1105b BB |
4716 | } |
4717 | ||
4718 | /* | |
4719 | * Now we need to entangle the css into the existing css_sets. unlike | |
4720 | * in cgroup_init_subsys, there are now multiple css_sets, so each one | |
4721 | * will need a new pointer to it; done by iterating the css_set_table. | |
4722 | * furthermore, modifying the existing css_sets will corrupt the hash | |
4723 | * table state, so each changed css_set will need its hash recomputed. | |
4724 | * this is all done under the css_set_lock. | |
4725 | */ | |
4726 | write_lock(&css_set_lock); | |
5abb8855 | 4727 | hash_for_each_safe(css_set_table, i, tmp, cset, hlist) { |
0ac801fe | 4728 | /* skip entries that we already rehashed */ |
5abb8855 | 4729 | if (cset->subsys[ss->subsys_id]) |
0ac801fe LZ |
4730 | continue; |
4731 | /* remove existing entry */ | |
5abb8855 | 4732 | hash_del(&cset->hlist); |
0ac801fe | 4733 | /* set new value */ |
5abb8855 | 4734 | cset->subsys[ss->subsys_id] = css; |
0ac801fe | 4735 | /* recompute hash and restore entry */ |
5abb8855 TH |
4736 | key = css_set_hash(cset->subsys); |
4737 | hash_add(css_set_table, &cset->hlist, key); | |
e6a1105b BB |
4738 | } |
4739 | write_unlock(&css_set_lock); | |
4740 | ||
b1929db4 TH |
4741 | ret = online_css(ss, dummytop); |
4742 | if (ret) | |
4743 | goto err_unload; | |
a8638030 | 4744 | |
e6a1105b BB |
4745 | /* success! */ |
4746 | mutex_unlock(&cgroup_mutex); | |
4747 | return 0; | |
d19e19de TH |
4748 | |
4749 | err_unload: | |
4750 | mutex_unlock(&cgroup_mutex); | |
4751 | /* @ss can't be mounted here as try_module_get() would fail */ | |
4752 | cgroup_unload_subsys(ss); | |
4753 | return ret; | |
ddbcc7e8 | 4754 | } |
e6a1105b | 4755 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
ddbcc7e8 | 4756 | |
cf5d5941 BB |
4757 | /** |
4758 | * cgroup_unload_subsys: unload a modular subsystem | |
4759 | * @ss: the subsystem to unload | |
4760 | * | |
4761 | * This function should be called in a modular subsystem's exitcall. When this | |
4762 | * function is invoked, the refcount on the subsystem's module will be 0, so | |
4763 | * the subsystem will not be attached to any hierarchy. | |
4764 | */ | |
4765 | void cgroup_unload_subsys(struct cgroup_subsys *ss) | |
4766 | { | |
69d0206c | 4767 | struct cgrp_cset_link *link; |
cf5d5941 BB |
4768 | |
4769 | BUG_ON(ss->module == NULL); | |
4770 | ||
4771 | /* | |
4772 | * we shouldn't be called if the subsystem is in use, and the use of | |
4773 | * try_module_get in parse_cgroupfs_options should ensure that it | |
4774 | * doesn't start being used while we're killing it off. | |
4775 | */ | |
4776 | BUG_ON(ss->root != &rootnode); | |
4777 | ||
4778 | mutex_lock(&cgroup_mutex); | |
02ae7486 | 4779 | |
a31f2d3f | 4780 | offline_css(ss, dummytop); |
02ae7486 | 4781 | |
c897ff68 | 4782 | if (ss->use_id) |
02ae7486 | 4783 | idr_destroy(&ss->idr); |
02ae7486 | 4784 | |
cf5d5941 | 4785 | /* deassign the subsys_id */ |
cf5d5941 BB |
4786 | subsys[ss->subsys_id] = NULL; |
4787 | ||
4788 | /* remove subsystem from rootnode's list of subsystems */ | |
8d258797 | 4789 | list_del_init(&ss->sibling); |
cf5d5941 BB |
4790 | |
4791 | /* | |
4792 | * disentangle the css from all css_sets attached to the dummytop. as | |
4793 | * in loading, we need to pay our respects to the hashtable gods. | |
4794 | */ | |
4795 | write_lock(&css_set_lock); | |
69d0206c TH |
4796 | list_for_each_entry(link, &dummytop->cset_links, cset_link) { |
4797 | struct css_set *cset = link->cset; | |
0ac801fe | 4798 | unsigned long key; |
cf5d5941 | 4799 | |
5abb8855 TH |
4800 | hash_del(&cset->hlist); |
4801 | cset->subsys[ss->subsys_id] = NULL; | |
4802 | key = css_set_hash(cset->subsys); | |
4803 | hash_add(css_set_table, &cset->hlist, key); | |
cf5d5941 BB |
4804 | } |
4805 | write_unlock(&css_set_lock); | |
4806 | ||
4807 | /* | |
92fb9748 TH |
4808 | * remove subsystem's css from the dummytop and free it - need to |
4809 | * free before marking as null because ss->css_free needs the | |
4810 | * cgrp->subsys pointer to find their state. note that this also | |
4811 | * takes care of freeing the css_id. | |
cf5d5941 | 4812 | */ |
92fb9748 | 4813 | ss->css_free(dummytop); |
cf5d5941 BB |
4814 | dummytop->subsys[ss->subsys_id] = NULL; |
4815 | ||
4816 | mutex_unlock(&cgroup_mutex); | |
4817 | } | |
4818 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); | |
4819 | ||
ddbcc7e8 | 4820 | /** |
a043e3b2 LZ |
4821 | * cgroup_init_early - cgroup initialization at system boot |
4822 | * | |
4823 | * Initialize cgroups at system boot, and initialize any | |
4824 | * subsystems that request early init. | |
ddbcc7e8 PM |
4825 | */ |
4826 | int __init cgroup_init_early(void) | |
4827 | { | |
4828 | int i; | |
146aa1bd | 4829 | atomic_set(&init_css_set.refcount, 1); |
69d0206c | 4830 | INIT_LIST_HEAD(&init_css_set.cgrp_links); |
817929ec | 4831 | INIT_LIST_HEAD(&init_css_set.tasks); |
472b1053 | 4832 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 4833 | css_set_count = 1; |
ddbcc7e8 | 4834 | init_cgroup_root(&rootnode); |
817929ec PM |
4835 | root_count = 1; |
4836 | init_task.cgroups = &init_css_set; | |
4837 | ||
69d0206c TH |
4838 | init_cgrp_cset_link.cset = &init_css_set; |
4839 | init_cgrp_cset_link.cgrp = dummytop; | |
4840 | list_add(&init_cgrp_cset_link.cset_link, &rootnode.top_cgroup.cset_links); | |
4841 | list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links); | |
ddbcc7e8 | 4842 | |
be45c900 | 4843 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
ddbcc7e8 PM |
4844 | struct cgroup_subsys *ss = subsys[i]; |
4845 | ||
be45c900 DW |
4846 | /* at bootup time, we don't worry about modular subsystems */ |
4847 | if (!ss || ss->module) | |
4848 | continue; | |
4849 | ||
ddbcc7e8 PM |
4850 | BUG_ON(!ss->name); |
4851 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
92fb9748 TH |
4852 | BUG_ON(!ss->css_alloc); |
4853 | BUG_ON(!ss->css_free); | |
ddbcc7e8 | 4854 | if (ss->subsys_id != i) { |
cfe36bde | 4855 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
ddbcc7e8 PM |
4856 | ss->name, ss->subsys_id); |
4857 | BUG(); | |
4858 | } | |
4859 | ||
4860 | if (ss->early_init) | |
4861 | cgroup_init_subsys(ss); | |
4862 | } | |
4863 | return 0; | |
4864 | } | |
4865 | ||
4866 | /** | |
a043e3b2 LZ |
4867 | * cgroup_init - cgroup initialization |
4868 | * | |
4869 | * Register cgroup filesystem and /proc file, and initialize | |
4870 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4871 | */ |
4872 | int __init cgroup_init(void) | |
4873 | { | |
4874 | int err; | |
4875 | int i; | |
0ac801fe | 4876 | unsigned long key; |
a424316c PM |
4877 | |
4878 | err = bdi_init(&cgroup_backing_dev_info); | |
4879 | if (err) | |
4880 | return err; | |
ddbcc7e8 | 4881 | |
be45c900 | 4882 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
ddbcc7e8 | 4883 | struct cgroup_subsys *ss = subsys[i]; |
be45c900 DW |
4884 | |
4885 | /* at bootup time, we don't worry about modular subsystems */ | |
4886 | if (!ss || ss->module) | |
4887 | continue; | |
ddbcc7e8 PM |
4888 | if (!ss->early_init) |
4889 | cgroup_init_subsys(ss); | |
38460b48 | 4890 | if (ss->use_id) |
e6a1105b | 4891 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
ddbcc7e8 PM |
4892 | } |
4893 | ||
472b1053 | 4894 | /* Add init_css_set to the hash table */ |
0ac801fe LZ |
4895 | key = css_set_hash(init_css_set.subsys); |
4896 | hash_add(css_set_table, &init_css_set.hlist, key); | |
fa3ca07e TH |
4897 | |
4898 | /* allocate id for the dummy hierarchy */ | |
54e7b4eb TH |
4899 | mutex_lock(&cgroup_mutex); |
4900 | mutex_lock(&cgroup_root_mutex); | |
4901 | ||
fa3ca07e | 4902 | BUG_ON(cgroup_init_root_id(&rootnode)); |
676db4af | 4903 | |
54e7b4eb TH |
4904 | mutex_unlock(&cgroup_root_mutex); |
4905 | mutex_unlock(&cgroup_mutex); | |
4906 | ||
676db4af GK |
4907 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
4908 | if (!cgroup_kobj) { | |
4909 | err = -ENOMEM; | |
4910 | goto out; | |
4911 | } | |
4912 | ||
ddbcc7e8 | 4913 | err = register_filesystem(&cgroup_fs_type); |
676db4af GK |
4914 | if (err < 0) { |
4915 | kobject_put(cgroup_kobj); | |
ddbcc7e8 | 4916 | goto out; |
676db4af | 4917 | } |
ddbcc7e8 | 4918 | |
46ae220b | 4919 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
a424316c | 4920 | |
ddbcc7e8 | 4921 | out: |
a424316c PM |
4922 | if (err) |
4923 | bdi_destroy(&cgroup_backing_dev_info); | |
4924 | ||
ddbcc7e8 PM |
4925 | return err; |
4926 | } | |
b4f48b63 | 4927 | |
a424316c PM |
4928 | /* |
4929 | * proc_cgroup_show() | |
4930 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4931 | * - Used for /proc/<pid>/cgroup. | |
4932 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
4933 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 4934 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
4935 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
4936 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
4937 | * cgroup to top_cgroup. | |
4938 | */ | |
4939 | ||
4940 | /* TODO: Use a proper seq_file iterator */ | |
8d8b97ba | 4941 | int proc_cgroup_show(struct seq_file *m, void *v) |
a424316c PM |
4942 | { |
4943 | struct pid *pid; | |
4944 | struct task_struct *tsk; | |
4945 | char *buf; | |
4946 | int retval; | |
4947 | struct cgroupfs_root *root; | |
4948 | ||
4949 | retval = -ENOMEM; | |
4950 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
4951 | if (!buf) | |
4952 | goto out; | |
4953 | ||
4954 | retval = -ESRCH; | |
4955 | pid = m->private; | |
4956 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4957 | if (!tsk) | |
4958 | goto out_free; | |
4959 | ||
4960 | retval = 0; | |
4961 | ||
4962 | mutex_lock(&cgroup_mutex); | |
4963 | ||
e5f6a860 | 4964 | for_each_active_root(root) { |
a424316c | 4965 | struct cgroup_subsys *ss; |
bd89aabc | 4966 | struct cgroup *cgrp; |
a424316c PM |
4967 | int count = 0; |
4968 | ||
2c6ab6d2 | 4969 | seq_printf(m, "%d:", root->hierarchy_id); |
a424316c PM |
4970 | for_each_subsys(root, ss) |
4971 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
c6d57f33 PM |
4972 | if (strlen(root->name)) |
4973 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4974 | root->name); | |
a424316c | 4975 | seq_putc(m, ':'); |
7717f7ba | 4976 | cgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 4977 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
a424316c PM |
4978 | if (retval < 0) |
4979 | goto out_unlock; | |
4980 | seq_puts(m, buf); | |
4981 | seq_putc(m, '\n'); | |
4982 | } | |
4983 | ||
4984 | out_unlock: | |
4985 | mutex_unlock(&cgroup_mutex); | |
4986 | put_task_struct(tsk); | |
4987 | out_free: | |
4988 | kfree(buf); | |
4989 | out: | |
4990 | return retval; | |
4991 | } | |
4992 | ||
a424316c PM |
4993 | /* Display information about each subsystem and each hierarchy */ |
4994 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4995 | { | |
4996 | int i; | |
a424316c | 4997 | |
8bab8dde | 4998 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4999 | /* |
5000 | * ideally we don't want subsystems moving around while we do this. | |
5001 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
5002 | * subsys/hierarchy state. | |
5003 | */ | |
a424316c | 5004 | mutex_lock(&cgroup_mutex); |
a424316c PM |
5005 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
5006 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
5007 | if (ss == NULL) |
5008 | continue; | |
2c6ab6d2 PM |
5009 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
5010 | ss->name, ss->root->hierarchy_id, | |
8bab8dde | 5011 | ss->root->number_of_cgroups, !ss->disabled); |
a424316c PM |
5012 | } |
5013 | mutex_unlock(&cgroup_mutex); | |
5014 | return 0; | |
5015 | } | |
5016 | ||
5017 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
5018 | { | |
9dce07f1 | 5019 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
5020 | } |
5021 | ||
828c0950 | 5022 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
5023 | .open = cgroupstats_open, |
5024 | .read = seq_read, | |
5025 | .llseek = seq_lseek, | |
5026 | .release = single_release, | |
5027 | }; | |
5028 | ||
b4f48b63 PM |
5029 | /** |
5030 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
a043e3b2 | 5031 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 PM |
5032 | * |
5033 | * Description: A task inherits its parent's cgroup at fork(). | |
5034 | * | |
5035 | * A pointer to the shared css_set was automatically copied in | |
5036 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
9bb71308 TH |
5037 | * it was not made under the protection of RCU or cgroup_mutex, so |
5038 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might | |
5039 | * have already changed current->cgroups, allowing the previously | |
5040 | * referenced cgroup group to be removed and freed. | |
b4f48b63 PM |
5041 | * |
5042 | * At the point that cgroup_fork() is called, 'current' is the parent | |
5043 | * task, and the passed argument 'child' points to the child task. | |
5044 | */ | |
5045 | void cgroup_fork(struct task_struct *child) | |
5046 | { | |
9bb71308 | 5047 | task_lock(current); |
817929ec PM |
5048 | child->cgroups = current->cgroups; |
5049 | get_css_set(child->cgroups); | |
9bb71308 | 5050 | task_unlock(current); |
817929ec | 5051 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
5052 | } |
5053 | ||
817929ec | 5054 | /** |
a043e3b2 LZ |
5055 | * cgroup_post_fork - called on a new task after adding it to the task list |
5056 | * @child: the task in question | |
5057 | * | |
5edee61e TH |
5058 | * Adds the task to the list running through its css_set if necessary and |
5059 | * call the subsystem fork() callbacks. Has to be after the task is | |
5060 | * visible on the task list in case we race with the first call to | |
5061 | * cgroup_iter_start() - to guarantee that the new task ends up on its | |
5062 | * list. | |
a043e3b2 | 5063 | */ |
817929ec PM |
5064 | void cgroup_post_fork(struct task_struct *child) |
5065 | { | |
5edee61e TH |
5066 | int i; |
5067 | ||
3ce3230a FW |
5068 | /* |
5069 | * use_task_css_set_links is set to 1 before we walk the tasklist | |
5070 | * under the tasklist_lock and we read it here after we added the child | |
5071 | * to the tasklist under the tasklist_lock as well. If the child wasn't | |
5072 | * yet in the tasklist when we walked through it from | |
5073 | * cgroup_enable_task_cg_lists(), then use_task_css_set_links value | |
5074 | * should be visible now due to the paired locking and barriers implied | |
5075 | * by LOCK/UNLOCK: it is written before the tasklist_lock unlock | |
5076 | * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock | |
5077 | * lock on fork. | |
5078 | */ | |
817929ec PM |
5079 | if (use_task_css_set_links) { |
5080 | write_lock(&css_set_lock); | |
d8783832 TH |
5081 | task_lock(child); |
5082 | if (list_empty(&child->cg_list)) | |
817929ec | 5083 | list_add(&child->cg_list, &child->cgroups->tasks); |
d8783832 | 5084 | task_unlock(child); |
817929ec PM |
5085 | write_unlock(&css_set_lock); |
5086 | } | |
5edee61e TH |
5087 | |
5088 | /* | |
5089 | * Call ss->fork(). This must happen after @child is linked on | |
5090 | * css_set; otherwise, @child might change state between ->fork() | |
5091 | * and addition to css_set. | |
5092 | */ | |
5093 | if (need_forkexit_callback) { | |
7d8e0bf5 LZ |
5094 | /* |
5095 | * fork/exit callbacks are supported only for builtin | |
5096 | * subsystems, and the builtin section of the subsys | |
5097 | * array is immutable, so we don't need to lock the | |
5098 | * subsys array here. On the other hand, modular section | |
5099 | * of the array can be freed at module unload, so we | |
5100 | * can't touch that. | |
5101 | */ | |
5102 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
5edee61e TH |
5103 | struct cgroup_subsys *ss = subsys[i]; |
5104 | ||
5edee61e TH |
5105 | if (ss->fork) |
5106 | ss->fork(child); | |
5107 | } | |
5108 | } | |
817929ec | 5109 | } |
5edee61e | 5110 | |
b4f48b63 PM |
5111 | /** |
5112 | * cgroup_exit - detach cgroup from exiting task | |
5113 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 5114 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
5115 | * |
5116 | * Description: Detach cgroup from @tsk and release it. | |
5117 | * | |
5118 | * Note that cgroups marked notify_on_release force every task in | |
5119 | * them to take the global cgroup_mutex mutex when exiting. | |
5120 | * This could impact scaling on very large systems. Be reluctant to | |
5121 | * use notify_on_release cgroups where very high task exit scaling | |
5122 | * is required on large systems. | |
5123 | * | |
5124 | * the_top_cgroup_hack: | |
5125 | * | |
5126 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
5127 | * | |
5128 | * We call cgroup_exit() while the task is still competent to | |
5129 | * handle notify_on_release(), then leave the task attached to the | |
5130 | * root cgroup in each hierarchy for the remainder of its exit. | |
5131 | * | |
5132 | * To do this properly, we would increment the reference count on | |
5133 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
5134 | * code we would add a second cgroup function call, to drop that | |
5135 | * reference. This would just create an unnecessary hot spot on | |
5136 | * the top_cgroup reference count, to no avail. | |
5137 | * | |
5138 | * Normally, holding a reference to a cgroup without bumping its | |
5139 | * count is unsafe. The cgroup could go away, or someone could | |
5140 | * attach us to a different cgroup, decrementing the count on | |
5141 | * the first cgroup that we never incremented. But in this case, | |
5142 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
5143 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
5144 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
5145 | */ |
5146 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
5147 | { | |
5abb8855 | 5148 | struct css_set *cset; |
d41d5a01 | 5149 | int i; |
817929ec PM |
5150 | |
5151 | /* | |
5152 | * Unlink from the css_set task list if necessary. | |
5153 | * Optimistically check cg_list before taking | |
5154 | * css_set_lock | |
5155 | */ | |
5156 | if (!list_empty(&tsk->cg_list)) { | |
5157 | write_lock(&css_set_lock); | |
5158 | if (!list_empty(&tsk->cg_list)) | |
8d258797 | 5159 | list_del_init(&tsk->cg_list); |
817929ec PM |
5160 | write_unlock(&css_set_lock); |
5161 | } | |
5162 | ||
b4f48b63 PM |
5163 | /* Reassign the task to the init_css_set. */ |
5164 | task_lock(tsk); | |
5abb8855 | 5165 | cset = tsk->cgroups; |
817929ec | 5166 | tsk->cgroups = &init_css_set; |
d41d5a01 PZ |
5167 | |
5168 | if (run_callbacks && need_forkexit_callback) { | |
7d8e0bf5 LZ |
5169 | /* |
5170 | * fork/exit callbacks are supported only for builtin | |
5171 | * subsystems, see cgroup_post_fork() for details. | |
5172 | */ | |
5173 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
d41d5a01 | 5174 | struct cgroup_subsys *ss = subsys[i]; |
be45c900 | 5175 | |
d41d5a01 PZ |
5176 | if (ss->exit) { |
5177 | struct cgroup *old_cgrp = | |
5abb8855 | 5178 | rcu_dereference_raw(cset->subsys[i])->cgroup; |
d41d5a01 | 5179 | struct cgroup *cgrp = task_cgroup(tsk, i); |
761b3ef5 | 5180 | ss->exit(cgrp, old_cgrp, tsk); |
d41d5a01 PZ |
5181 | } |
5182 | } | |
5183 | } | |
b4f48b63 | 5184 | task_unlock(tsk); |
d41d5a01 | 5185 | |
5abb8855 | 5186 | put_css_set_taskexit(cset); |
b4f48b63 | 5187 | } |
697f4161 | 5188 | |
bd89aabc | 5189 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 5190 | { |
f50daa70 | 5191 | if (cgroup_is_releasable(cgrp) && |
6f3d828f | 5192 | list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) { |
f50daa70 LZ |
5193 | /* |
5194 | * Control Group is currently removeable. If it's not | |
81a6a5cd | 5195 | * already queued for a userspace notification, queue |
f50daa70 LZ |
5196 | * it now |
5197 | */ | |
81a6a5cd | 5198 | int need_schedule_work = 0; |
f50daa70 | 5199 | |
cdcc136f | 5200 | raw_spin_lock(&release_list_lock); |
54766d4a | 5201 | if (!cgroup_is_dead(cgrp) && |
bd89aabc PM |
5202 | list_empty(&cgrp->release_list)) { |
5203 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
5204 | need_schedule_work = 1; |
5205 | } | |
cdcc136f | 5206 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
5207 | if (need_schedule_work) |
5208 | schedule_work(&release_agent_work); | |
5209 | } | |
5210 | } | |
5211 | ||
81a6a5cd PM |
5212 | /* |
5213 | * Notify userspace when a cgroup is released, by running the | |
5214 | * configured release agent with the name of the cgroup (path | |
5215 | * relative to the root of cgroup file system) as the argument. | |
5216 | * | |
5217 | * Most likely, this user command will try to rmdir this cgroup. | |
5218 | * | |
5219 | * This races with the possibility that some other task will be | |
5220 | * attached to this cgroup before it is removed, or that some other | |
5221 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5222 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5223 | * unused, and this cgroup will be reprieved from its death sentence, | |
5224 | * to continue to serve a useful existence. Next time it's released, | |
5225 | * we will get notified again, if it still has 'notify_on_release' set. | |
5226 | * | |
5227 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5228 | * means only wait until the task is successfully execve()'d. The | |
5229 | * separate release agent task is forked by call_usermodehelper(), | |
5230 | * then control in this thread returns here, without waiting for the | |
5231 | * release agent task. We don't bother to wait because the caller of | |
5232 | * this routine has no use for the exit status of the release agent | |
5233 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5234 | */ |
81a6a5cd PM |
5235 | static void cgroup_release_agent(struct work_struct *work) |
5236 | { | |
5237 | BUG_ON(work != &release_agent_work); | |
5238 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 5239 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
5240 | while (!list_empty(&release_list)) { |
5241 | char *argv[3], *envp[3]; | |
5242 | int i; | |
e788e066 | 5243 | char *pathbuf = NULL, *agentbuf = NULL; |
bd89aabc | 5244 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
5245 | struct cgroup, |
5246 | release_list); | |
bd89aabc | 5247 | list_del_init(&cgrp->release_list); |
cdcc136f | 5248 | raw_spin_unlock(&release_list_lock); |
81a6a5cd | 5249 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
e788e066 PM |
5250 | if (!pathbuf) |
5251 | goto continue_free; | |
5252 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
5253 | goto continue_free; | |
5254 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5255 | if (!agentbuf) | |
5256 | goto continue_free; | |
81a6a5cd PM |
5257 | |
5258 | i = 0; | |
e788e066 PM |
5259 | argv[i++] = agentbuf; |
5260 | argv[i++] = pathbuf; | |
81a6a5cd PM |
5261 | argv[i] = NULL; |
5262 | ||
5263 | i = 0; | |
5264 | /* minimal command environment */ | |
5265 | envp[i++] = "HOME=/"; | |
5266 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5267 | envp[i] = NULL; | |
5268 | ||
5269 | /* Drop the lock while we invoke the usermode helper, | |
5270 | * since the exec could involve hitting disk and hence | |
5271 | * be a slow process */ | |
5272 | mutex_unlock(&cgroup_mutex); | |
5273 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 5274 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
5275 | continue_free: |
5276 | kfree(pathbuf); | |
5277 | kfree(agentbuf); | |
cdcc136f | 5278 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 5279 | } |
cdcc136f | 5280 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
5281 | mutex_unlock(&cgroup_mutex); |
5282 | } | |
8bab8dde PM |
5283 | |
5284 | static int __init cgroup_disable(char *str) | |
5285 | { | |
5286 | int i; | |
5287 | char *token; | |
5288 | ||
5289 | while ((token = strsep(&str, ",")) != NULL) { | |
5290 | if (!*token) | |
5291 | continue; | |
be45c900 | 5292 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
8bab8dde PM |
5293 | struct cgroup_subsys *ss = subsys[i]; |
5294 | ||
be45c900 DW |
5295 | /* |
5296 | * cgroup_disable, being at boot time, can't | |
5297 | * know about module subsystems, so we don't | |
5298 | * worry about them. | |
5299 | */ | |
5300 | if (!ss || ss->module) | |
5301 | continue; | |
5302 | ||
8bab8dde PM |
5303 | if (!strcmp(token, ss->name)) { |
5304 | ss->disabled = 1; | |
5305 | printk(KERN_INFO "Disabling %s control group" | |
5306 | " subsystem\n", ss->name); | |
5307 | break; | |
5308 | } | |
5309 | } | |
5310 | } | |
5311 | return 1; | |
5312 | } | |
5313 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 KH |
5314 | |
5315 | /* | |
5316 | * Functons for CSS ID. | |
5317 | */ | |
5318 | ||
54766d4a | 5319 | /* to get ID other than 0, this should be called when !cgroup_is_dead() */ |
38460b48 KH |
5320 | unsigned short css_id(struct cgroup_subsys_state *css) |
5321 | { | |
7f0f1546 KH |
5322 | struct css_id *cssid; |
5323 | ||
5324 | /* | |
5325 | * This css_id() can return correct value when somone has refcnt | |
5326 | * on this or this is under rcu_read_lock(). Once css->id is allocated, | |
5327 | * it's unchanged until freed. | |
5328 | */ | |
d3daf28d | 5329 | cssid = rcu_dereference_raw(css->id); |
38460b48 KH |
5330 | |
5331 | if (cssid) | |
5332 | return cssid->id; | |
5333 | return 0; | |
5334 | } | |
67523c48 | 5335 | EXPORT_SYMBOL_GPL(css_id); |
38460b48 | 5336 | |
747388d7 KH |
5337 | /** |
5338 | * css_is_ancestor - test "root" css is an ancestor of "child" | |
5339 | * @child: the css to be tested. | |
5340 | * @root: the css supporsed to be an ancestor of the child. | |
5341 | * | |
5342 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because | |
91c63734 | 5343 | * this function reads css->id, the caller must hold rcu_read_lock(). |
747388d7 KH |
5344 | * But, considering usual usage, the csses should be valid objects after test. |
5345 | * Assuming that the caller will do some action to the child if this returns | |
5346 | * returns true, the caller must take "child";s reference count. | |
5347 | * If "child" is valid object and this returns true, "root" is valid, too. | |
5348 | */ | |
5349 | ||
38460b48 | 5350 | bool css_is_ancestor(struct cgroup_subsys_state *child, |
0b7f569e | 5351 | const struct cgroup_subsys_state *root) |
38460b48 | 5352 | { |
747388d7 KH |
5353 | struct css_id *child_id; |
5354 | struct css_id *root_id; | |
38460b48 | 5355 | |
747388d7 | 5356 | child_id = rcu_dereference(child->id); |
91c63734 JW |
5357 | if (!child_id) |
5358 | return false; | |
747388d7 | 5359 | root_id = rcu_dereference(root->id); |
91c63734 JW |
5360 | if (!root_id) |
5361 | return false; | |
5362 | if (child_id->depth < root_id->depth) | |
5363 | return false; | |
5364 | if (child_id->stack[root_id->depth] != root_id->id) | |
5365 | return false; | |
5366 | return true; | |
38460b48 KH |
5367 | } |
5368 | ||
38460b48 KH |
5369 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
5370 | { | |
5371 | struct css_id *id = css->id; | |
5372 | /* When this is called before css_id initialization, id can be NULL */ | |
5373 | if (!id) | |
5374 | return; | |
5375 | ||
5376 | BUG_ON(!ss->use_id); | |
5377 | ||
5378 | rcu_assign_pointer(id->css, NULL); | |
5379 | rcu_assign_pointer(css->id, NULL); | |
42aee6c4 | 5380 | spin_lock(&ss->id_lock); |
38460b48 | 5381 | idr_remove(&ss->idr, id->id); |
42aee6c4 | 5382 | spin_unlock(&ss->id_lock); |
025cea99 | 5383 | kfree_rcu(id, rcu_head); |
38460b48 | 5384 | } |
67523c48 | 5385 | EXPORT_SYMBOL_GPL(free_css_id); |
38460b48 KH |
5386 | |
5387 | /* | |
5388 | * This is called by init or create(). Then, calls to this function are | |
5389 | * always serialized (By cgroup_mutex() at create()). | |
5390 | */ | |
5391 | ||
5392 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
5393 | { | |
5394 | struct css_id *newid; | |
d228d9ec | 5395 | int ret, size; |
38460b48 KH |
5396 | |
5397 | BUG_ON(!ss->use_id); | |
5398 | ||
5399 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
5400 | newid = kzalloc(size, GFP_KERNEL); | |
5401 | if (!newid) | |
5402 | return ERR_PTR(-ENOMEM); | |
d228d9ec TH |
5403 | |
5404 | idr_preload(GFP_KERNEL); | |
42aee6c4 | 5405 | spin_lock(&ss->id_lock); |
38460b48 | 5406 | /* Don't use 0. allocates an ID of 1-65535 */ |
d228d9ec | 5407 | ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT); |
42aee6c4 | 5408 | spin_unlock(&ss->id_lock); |
d228d9ec | 5409 | idr_preload_end(); |
38460b48 KH |
5410 | |
5411 | /* Returns error when there are no free spaces for new ID.*/ | |
d228d9ec | 5412 | if (ret < 0) |
38460b48 | 5413 | goto err_out; |
38460b48 | 5414 | |
d228d9ec | 5415 | newid->id = ret; |
38460b48 KH |
5416 | newid->depth = depth; |
5417 | return newid; | |
38460b48 KH |
5418 | err_out: |
5419 | kfree(newid); | |
d228d9ec | 5420 | return ERR_PTR(ret); |
38460b48 KH |
5421 | |
5422 | } | |
5423 | ||
e6a1105b BB |
5424 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
5425 | struct cgroup_subsys_state *rootcss) | |
38460b48 KH |
5426 | { |
5427 | struct css_id *newid; | |
38460b48 | 5428 | |
42aee6c4 | 5429 | spin_lock_init(&ss->id_lock); |
38460b48 KH |
5430 | idr_init(&ss->idr); |
5431 | ||
38460b48 KH |
5432 | newid = get_new_cssid(ss, 0); |
5433 | if (IS_ERR(newid)) | |
5434 | return PTR_ERR(newid); | |
5435 | ||
5436 | newid->stack[0] = newid->id; | |
5437 | newid->css = rootcss; | |
5438 | rootcss->id = newid; | |
5439 | return 0; | |
5440 | } | |
5441 | ||
5442 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
5443 | struct cgroup *child) | |
5444 | { | |
5445 | int subsys_id, i, depth = 0; | |
5446 | struct cgroup_subsys_state *parent_css, *child_css; | |
fae9c791 | 5447 | struct css_id *child_id, *parent_id; |
38460b48 KH |
5448 | |
5449 | subsys_id = ss->subsys_id; | |
5450 | parent_css = parent->subsys[subsys_id]; | |
5451 | child_css = child->subsys[subsys_id]; | |
38460b48 | 5452 | parent_id = parent_css->id; |
94b3dd0f | 5453 | depth = parent_id->depth + 1; |
38460b48 KH |
5454 | |
5455 | child_id = get_new_cssid(ss, depth); | |
5456 | if (IS_ERR(child_id)) | |
5457 | return PTR_ERR(child_id); | |
5458 | ||
5459 | for (i = 0; i < depth; i++) | |
5460 | child_id->stack[i] = parent_id->stack[i]; | |
5461 | child_id->stack[depth] = child_id->id; | |
5462 | /* | |
5463 | * child_id->css pointer will be set after this cgroup is available | |
5464 | * see cgroup_populate_dir() | |
5465 | */ | |
5466 | rcu_assign_pointer(child_css->id, child_id); | |
5467 | ||
5468 | return 0; | |
5469 | } | |
5470 | ||
5471 | /** | |
5472 | * css_lookup - lookup css by id | |
5473 | * @ss: cgroup subsys to be looked into. | |
5474 | * @id: the id | |
5475 | * | |
5476 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
5477 | * NULL if not. Should be called under rcu_read_lock() | |
5478 | */ | |
5479 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
5480 | { | |
5481 | struct css_id *cssid = NULL; | |
5482 | ||
5483 | BUG_ON(!ss->use_id); | |
5484 | cssid = idr_find(&ss->idr, id); | |
5485 | ||
5486 | if (unlikely(!cssid)) | |
5487 | return NULL; | |
5488 | ||
5489 | return rcu_dereference(cssid->css); | |
5490 | } | |
67523c48 | 5491 | EXPORT_SYMBOL_GPL(css_lookup); |
38460b48 | 5492 | |
e5d1367f SE |
5493 | /* |
5494 | * get corresponding css from file open on cgroupfs directory | |
5495 | */ | |
5496 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) | |
5497 | { | |
5498 | struct cgroup *cgrp; | |
5499 | struct inode *inode; | |
5500 | struct cgroup_subsys_state *css; | |
5501 | ||
496ad9aa | 5502 | inode = file_inode(f); |
e5d1367f SE |
5503 | /* check in cgroup filesystem dir */ |
5504 | if (inode->i_op != &cgroup_dir_inode_operations) | |
5505 | return ERR_PTR(-EBADF); | |
5506 | ||
5507 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) | |
5508 | return ERR_PTR(-EINVAL); | |
5509 | ||
5510 | /* get cgroup */ | |
5511 | cgrp = __d_cgrp(f->f_dentry); | |
5512 | css = cgrp->subsys[id]; | |
5513 | return css ? css : ERR_PTR(-ENOENT); | |
5514 | } | |
5515 | ||
fe693435 | 5516 | #ifdef CONFIG_CGROUP_DEBUG |
92fb9748 | 5517 | static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cont) |
fe693435 PM |
5518 | { |
5519 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5520 | ||
5521 | if (!css) | |
5522 | return ERR_PTR(-ENOMEM); | |
5523 | ||
5524 | return css; | |
5525 | } | |
5526 | ||
92fb9748 | 5527 | static void debug_css_free(struct cgroup *cont) |
fe693435 PM |
5528 | { |
5529 | kfree(cont->subsys[debug_subsys_id]); | |
5530 | } | |
5531 | ||
fe693435 PM |
5532 | static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) |
5533 | { | |
5534 | return cgroup_task_count(cont); | |
5535 | } | |
5536 | ||
5537 | static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) | |
5538 | { | |
5539 | return (u64)(unsigned long)current->cgroups; | |
5540 | } | |
5541 | ||
5542 | static u64 current_css_set_refcount_read(struct cgroup *cont, | |
5543 | struct cftype *cft) | |
5544 | { | |
5545 | u64 count; | |
5546 | ||
5547 | rcu_read_lock(); | |
5548 | count = atomic_read(¤t->cgroups->refcount); | |
5549 | rcu_read_unlock(); | |
5550 | return count; | |
5551 | } | |
5552 | ||
7717f7ba PM |
5553 | static int current_css_set_cg_links_read(struct cgroup *cont, |
5554 | struct cftype *cft, | |
5555 | struct seq_file *seq) | |
5556 | { | |
69d0206c | 5557 | struct cgrp_cset_link *link; |
5abb8855 | 5558 | struct css_set *cset; |
7717f7ba PM |
5559 | |
5560 | read_lock(&css_set_lock); | |
5561 | rcu_read_lock(); | |
5abb8855 | 5562 | cset = rcu_dereference(current->cgroups); |
69d0206c | 5563 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba PM |
5564 | struct cgroup *c = link->cgrp; |
5565 | const char *name; | |
5566 | ||
5567 | if (c->dentry) | |
5568 | name = c->dentry->d_name.name; | |
5569 | else | |
5570 | name = "?"; | |
2c6ab6d2 PM |
5571 | seq_printf(seq, "Root %d group %s\n", |
5572 | c->root->hierarchy_id, name); | |
7717f7ba PM |
5573 | } |
5574 | rcu_read_unlock(); | |
5575 | read_unlock(&css_set_lock); | |
5576 | return 0; | |
5577 | } | |
5578 | ||
5579 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
5580 | static int cgroup_css_links_read(struct cgroup *cont, | |
5581 | struct cftype *cft, | |
5582 | struct seq_file *seq) | |
5583 | { | |
69d0206c | 5584 | struct cgrp_cset_link *link; |
7717f7ba PM |
5585 | |
5586 | read_lock(&css_set_lock); | |
69d0206c TH |
5587 | list_for_each_entry(link, &cont->cset_links, cset_link) { |
5588 | struct css_set *cset = link->cset; | |
7717f7ba PM |
5589 | struct task_struct *task; |
5590 | int count = 0; | |
5abb8855 TH |
5591 | seq_printf(seq, "css_set %p\n", cset); |
5592 | list_for_each_entry(task, &cset->tasks, cg_list) { | |
7717f7ba PM |
5593 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { |
5594 | seq_puts(seq, " ...\n"); | |
5595 | break; | |
5596 | } else { | |
5597 | seq_printf(seq, " task %d\n", | |
5598 | task_pid_vnr(task)); | |
5599 | } | |
5600 | } | |
5601 | } | |
5602 | read_unlock(&css_set_lock); | |
5603 | return 0; | |
5604 | } | |
5605 | ||
fe693435 PM |
5606 | static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) |
5607 | { | |
5608 | return test_bit(CGRP_RELEASABLE, &cgrp->flags); | |
5609 | } | |
5610 | ||
5611 | static struct cftype debug_files[] = { | |
fe693435 PM |
5612 | { |
5613 | .name = "taskcount", | |
5614 | .read_u64 = debug_taskcount_read, | |
5615 | }, | |
5616 | ||
5617 | { | |
5618 | .name = "current_css_set", | |
5619 | .read_u64 = current_css_set_read, | |
5620 | }, | |
5621 | ||
5622 | { | |
5623 | .name = "current_css_set_refcount", | |
5624 | .read_u64 = current_css_set_refcount_read, | |
5625 | }, | |
5626 | ||
7717f7ba PM |
5627 | { |
5628 | .name = "current_css_set_cg_links", | |
5629 | .read_seq_string = current_css_set_cg_links_read, | |
5630 | }, | |
5631 | ||
5632 | { | |
5633 | .name = "cgroup_css_links", | |
5634 | .read_seq_string = cgroup_css_links_read, | |
5635 | }, | |
5636 | ||
fe693435 PM |
5637 | { |
5638 | .name = "releasable", | |
5639 | .read_u64 = releasable_read, | |
5640 | }, | |
fe693435 | 5641 | |
4baf6e33 TH |
5642 | { } /* terminate */ |
5643 | }; | |
fe693435 PM |
5644 | |
5645 | struct cgroup_subsys debug_subsys = { | |
5646 | .name = "debug", | |
92fb9748 TH |
5647 | .css_alloc = debug_css_alloc, |
5648 | .css_free = debug_css_free, | |
fe693435 | 5649 | .subsys_id = debug_subsys_id, |
4baf6e33 | 5650 | .base_cftypes = debug_files, |
fe693435 PM |
5651 | }; |
5652 | #endif /* CONFIG_CGROUP_DEBUG */ |