Commit | Line | Data |
---|---|---|
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> | |
c6d57f33 | 30 | #include <linux/ctype.h> |
ddbcc7e8 PM |
31 | #include <linux/errno.h> |
32 | #include <linux/fs.h> | |
33 | #include <linux/kernel.h> | |
34 | #include <linux/list.h> | |
35 | #include <linux/mm.h> | |
36 | #include <linux/mutex.h> | |
37 | #include <linux/mount.h> | |
38 | #include <linux/pagemap.h> | |
a424316c | 39 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
40 | #include <linux/rcupdate.h> |
41 | #include <linux/sched.h> | |
817929ec | 42 | #include <linux/backing-dev.h> |
ddbcc7e8 PM |
43 | #include <linux/seq_file.h> |
44 | #include <linux/slab.h> | |
45 | #include <linux/magic.h> | |
46 | #include <linux/spinlock.h> | |
47 | #include <linux/string.h> | |
bbcb81d0 | 48 | #include <linux/sort.h> |
81a6a5cd | 49 | #include <linux/kmod.h> |
e6a1105b | 50 | #include <linux/module.h> |
846c7bb0 BS |
51 | #include <linux/delayacct.h> |
52 | #include <linux/cgroupstats.h> | |
472b1053 | 53 | #include <linux/hash.h> |
3f8206d4 | 54 | #include <linux/namei.h> |
096b7fe0 | 55 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 56 | #include <linux/idr.h> |
d1d9fd33 | 57 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
0dea1168 KS |
58 | #include <linux/eventfd.h> |
59 | #include <linux/poll.h> | |
846c7bb0 | 60 | |
ddbcc7e8 PM |
61 | #include <asm/atomic.h> |
62 | ||
81a6a5cd PM |
63 | static DEFINE_MUTEX(cgroup_mutex); |
64 | ||
aae8aab4 BB |
65 | /* |
66 | * Generate an array of cgroup subsystem pointers. At boot time, this is | |
67 | * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are | |
68 | * registered after that. The mutable section of this array is protected by | |
69 | * cgroup_mutex. | |
70 | */ | |
ddbcc7e8 | 71 | #define SUBSYS(_x) &_x ## _subsys, |
aae8aab4 | 72 | static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { |
ddbcc7e8 PM |
73 | #include <linux/cgroup_subsys.h> |
74 | }; | |
75 | ||
c6d57f33 PM |
76 | #define MAX_CGROUP_ROOT_NAMELEN 64 |
77 | ||
ddbcc7e8 PM |
78 | /* |
79 | * A cgroupfs_root represents the root of a cgroup hierarchy, | |
80 | * and may be associated with a superblock to form an active | |
81 | * hierarchy | |
82 | */ | |
83 | struct cgroupfs_root { | |
84 | struct super_block *sb; | |
85 | ||
86 | /* | |
87 | * The bitmask of subsystems intended to be attached to this | |
88 | * hierarchy | |
89 | */ | |
90 | unsigned long subsys_bits; | |
91 | ||
2c6ab6d2 PM |
92 | /* Unique id for this hierarchy. */ |
93 | int hierarchy_id; | |
94 | ||
ddbcc7e8 PM |
95 | /* The bitmask of subsystems currently attached to this hierarchy */ |
96 | unsigned long actual_subsys_bits; | |
97 | ||
98 | /* A list running through the attached subsystems */ | |
99 | struct list_head subsys_list; | |
100 | ||
101 | /* The root cgroup for this hierarchy */ | |
102 | struct cgroup top_cgroup; | |
103 | ||
104 | /* Tracks how many cgroups are currently defined in hierarchy.*/ | |
105 | int number_of_cgroups; | |
106 | ||
e5f6a860 | 107 | /* A list running through the active hierarchies */ |
ddbcc7e8 PM |
108 | struct list_head root_list; |
109 | ||
110 | /* Hierarchy-specific flags */ | |
111 | unsigned long flags; | |
81a6a5cd | 112 | |
e788e066 | 113 | /* The path to use for release notifications. */ |
81a6a5cd | 114 | char release_agent_path[PATH_MAX]; |
c6d57f33 PM |
115 | |
116 | /* The name for this hierarchy - may be empty */ | |
117 | char name[MAX_CGROUP_ROOT_NAMELEN]; | |
ddbcc7e8 PM |
118 | }; |
119 | ||
ddbcc7e8 PM |
120 | /* |
121 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the | |
122 | * subsystems that are otherwise unattached - it never has more than a | |
123 | * single cgroup, and all tasks are part of that cgroup. | |
124 | */ | |
125 | static struct cgroupfs_root rootnode; | |
126 | ||
38460b48 KH |
127 | /* |
128 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when | |
129 | * cgroup_subsys->use_id != 0. | |
130 | */ | |
131 | #define CSS_ID_MAX (65535) | |
132 | struct css_id { | |
133 | /* | |
134 | * The css to which this ID points. This pointer is set to valid value | |
135 | * after cgroup is populated. If cgroup is removed, this will be NULL. | |
136 | * This pointer is expected to be RCU-safe because destroy() | |
137 | * is called after synchronize_rcu(). But for safe use, css_is_removed() | |
138 | * css_tryget() should be used for avoiding race. | |
139 | */ | |
2c392b8c | 140 | struct cgroup_subsys_state __rcu *css; |
38460b48 KH |
141 | /* |
142 | * ID of this css. | |
143 | */ | |
144 | unsigned short id; | |
145 | /* | |
146 | * Depth in hierarchy which this ID belongs to. | |
147 | */ | |
148 | unsigned short depth; | |
149 | /* | |
150 | * ID is freed by RCU. (and lookup routine is RCU safe.) | |
151 | */ | |
152 | struct rcu_head rcu_head; | |
153 | /* | |
154 | * Hierarchy of CSS ID belongs to. | |
155 | */ | |
156 | unsigned short stack[0]; /* Array of Length (depth+1) */ | |
157 | }; | |
158 | ||
0dea1168 | 159 | /* |
25985edc | 160 | * cgroup_event represents events which userspace want to receive. |
0dea1168 KS |
161 | */ |
162 | struct cgroup_event { | |
163 | /* | |
164 | * Cgroup which the event belongs to. | |
165 | */ | |
166 | struct cgroup *cgrp; | |
167 | /* | |
168 | * Control file which the event associated. | |
169 | */ | |
170 | struct cftype *cft; | |
171 | /* | |
172 | * eventfd to signal userspace about the event. | |
173 | */ | |
174 | struct eventfd_ctx *eventfd; | |
175 | /* | |
176 | * Each of these stored in a list by the cgroup. | |
177 | */ | |
178 | struct list_head list; | |
179 | /* | |
180 | * All fields below needed to unregister event when | |
181 | * userspace closes eventfd. | |
182 | */ | |
183 | poll_table pt; | |
184 | wait_queue_head_t *wqh; | |
185 | wait_queue_t wait; | |
186 | struct work_struct remove; | |
187 | }; | |
38460b48 | 188 | |
ddbcc7e8 PM |
189 | /* The list of hierarchy roots */ |
190 | ||
191 | static LIST_HEAD(roots); | |
817929ec | 192 | static int root_count; |
ddbcc7e8 | 193 | |
2c6ab6d2 PM |
194 | static DEFINE_IDA(hierarchy_ida); |
195 | static int next_hierarchy_id; | |
196 | static DEFINE_SPINLOCK(hierarchy_id_lock); | |
197 | ||
ddbcc7e8 PM |
198 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ |
199 | #define dummytop (&rootnode.top_cgroup) | |
200 | ||
201 | /* This flag indicates whether tasks in the fork and exit paths should | |
a043e3b2 LZ |
202 | * check for fork/exit handlers to call. This avoids us having to do |
203 | * extra work in the fork/exit path if none of the subsystems need to | |
204 | * be called. | |
ddbcc7e8 | 205 | */ |
8947f9d5 | 206 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 207 | |
d11c563d PM |
208 | #ifdef CONFIG_PROVE_LOCKING |
209 | int cgroup_lock_is_held(void) | |
210 | { | |
211 | return lockdep_is_held(&cgroup_mutex); | |
212 | } | |
213 | #else /* #ifdef CONFIG_PROVE_LOCKING */ | |
214 | int cgroup_lock_is_held(void) | |
215 | { | |
216 | return mutex_is_locked(&cgroup_mutex); | |
217 | } | |
218 | #endif /* #else #ifdef CONFIG_PROVE_LOCKING */ | |
219 | ||
220 | EXPORT_SYMBOL_GPL(cgroup_lock_is_held); | |
221 | ||
ddbcc7e8 | 222 | /* convenient tests for these bits */ |
bd89aabc | 223 | inline int cgroup_is_removed(const struct cgroup *cgrp) |
ddbcc7e8 | 224 | { |
bd89aabc | 225 | return test_bit(CGRP_REMOVED, &cgrp->flags); |
ddbcc7e8 PM |
226 | } |
227 | ||
228 | /* bits in struct cgroupfs_root flags field */ | |
229 | enum { | |
230 | ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ | |
231 | }; | |
232 | ||
e9685a03 | 233 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
234 | { |
235 | const int bits = | |
bd89aabc PM |
236 | (1 << CGRP_RELEASABLE) | |
237 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
238 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
239 | } |
240 | ||
e9685a03 | 241 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 242 | { |
bd89aabc | 243 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
244 | } |
245 | ||
97978e6d DL |
246 | static int clone_children(const struct cgroup *cgrp) |
247 | { | |
248 | return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
249 | } | |
250 | ||
ddbcc7e8 PM |
251 | /* |
252 | * for_each_subsys() allows you to iterate on each subsystem attached to | |
253 | * an active hierarchy | |
254 | */ | |
255 | #define for_each_subsys(_root, _ss) \ | |
256 | list_for_each_entry(_ss, &_root->subsys_list, sibling) | |
257 | ||
e5f6a860 LZ |
258 | /* for_each_active_root() allows you to iterate across the active hierarchies */ |
259 | #define for_each_active_root(_root) \ | |
ddbcc7e8 PM |
260 | list_for_each_entry(_root, &roots, root_list) |
261 | ||
81a6a5cd PM |
262 | /* the list of cgroups eligible for automatic release. Protected by |
263 | * release_list_lock */ | |
264 | static LIST_HEAD(release_list); | |
265 | static DEFINE_SPINLOCK(release_list_lock); | |
266 | static void cgroup_release_agent(struct work_struct *work); | |
267 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 268 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 269 | |
817929ec PM |
270 | /* Link structure for associating css_set objects with cgroups */ |
271 | struct cg_cgroup_link { | |
272 | /* | |
273 | * List running through cg_cgroup_links associated with a | |
274 | * cgroup, anchored on cgroup->css_sets | |
275 | */ | |
bd89aabc | 276 | struct list_head cgrp_link_list; |
7717f7ba | 277 | struct cgroup *cgrp; |
817929ec PM |
278 | /* |
279 | * List running through cg_cgroup_links pointing at a | |
280 | * single css_set object, anchored on css_set->cg_links | |
281 | */ | |
282 | struct list_head cg_link_list; | |
283 | struct css_set *cg; | |
284 | }; | |
285 | ||
286 | /* The default css_set - used by init and its children prior to any | |
287 | * hierarchies being mounted. It contains a pointer to the root state | |
288 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
289 | * reference-counted, to improve performance when child cgroups | |
290 | * haven't been created. | |
291 | */ | |
292 | ||
293 | static struct css_set init_css_set; | |
294 | static struct cg_cgroup_link init_css_set_link; | |
295 | ||
e6a1105b BB |
296 | static int cgroup_init_idr(struct cgroup_subsys *ss, |
297 | struct cgroup_subsys_state *css); | |
38460b48 | 298 | |
817929ec PM |
299 | /* css_set_lock protects the list of css_set objects, and the |
300 | * chain of tasks off each css_set. Nests outside task->alloc_lock | |
301 | * due to cgroup_iter_start() */ | |
302 | static DEFINE_RWLOCK(css_set_lock); | |
303 | static int css_set_count; | |
304 | ||
7717f7ba PM |
305 | /* |
306 | * hash table for cgroup groups. This improves the performance to find | |
307 | * an existing css_set. This hash doesn't (currently) take into | |
308 | * account cgroups in empty hierarchies. | |
309 | */ | |
472b1053 LZ |
310 | #define CSS_SET_HASH_BITS 7 |
311 | #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) | |
312 | static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; | |
313 | ||
314 | static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) | |
315 | { | |
316 | int i; | |
317 | int index; | |
318 | unsigned long tmp = 0UL; | |
319 | ||
320 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) | |
321 | tmp += (unsigned long)css[i]; | |
322 | tmp = (tmp >> 16) ^ tmp; | |
323 | ||
324 | index = hash_long(tmp, CSS_SET_HASH_BITS); | |
325 | ||
326 | return &css_set_table[index]; | |
327 | } | |
328 | ||
817929ec PM |
329 | /* We don't maintain the lists running through each css_set to its |
330 | * task until after the first call to cgroup_iter_start(). This | |
331 | * reduces the fork()/exit() overhead for people who have cgroups | |
332 | * compiled into their kernel but not actually in use */ | |
8947f9d5 | 333 | static int use_task_css_set_links __read_mostly; |
817929ec | 334 | |
2c6ab6d2 | 335 | static void __put_css_set(struct css_set *cg, int taskexit) |
b4f48b63 | 336 | { |
71cbb949 KM |
337 | struct cg_cgroup_link *link; |
338 | struct cg_cgroup_link *saved_link; | |
146aa1bd LJ |
339 | /* |
340 | * Ensure that the refcount doesn't hit zero while any readers | |
341 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
342 | * rwlock | |
343 | */ | |
344 | if (atomic_add_unless(&cg->refcount, -1, 1)) | |
345 | return; | |
346 | write_lock(&css_set_lock); | |
347 | if (!atomic_dec_and_test(&cg->refcount)) { | |
348 | write_unlock(&css_set_lock); | |
349 | return; | |
350 | } | |
81a6a5cd | 351 | |
2c6ab6d2 PM |
352 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
353 | hlist_del(&cg->hlist); | |
354 | css_set_count--; | |
355 | ||
356 | list_for_each_entry_safe(link, saved_link, &cg->cg_links, | |
357 | cg_link_list) { | |
358 | struct cgroup *cgrp = link->cgrp; | |
359 | list_del(&link->cg_link_list); | |
360 | list_del(&link->cgrp_link_list); | |
bd89aabc PM |
361 | if (atomic_dec_and_test(&cgrp->count) && |
362 | notify_on_release(cgrp)) { | |
81a6a5cd | 363 | if (taskexit) |
bd89aabc PM |
364 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
365 | check_for_release(cgrp); | |
81a6a5cd | 366 | } |
2c6ab6d2 PM |
367 | |
368 | kfree(link); | |
81a6a5cd | 369 | } |
2c6ab6d2 PM |
370 | |
371 | write_unlock(&css_set_lock); | |
30088ad8 | 372 | kfree_rcu(cg, rcu_head); |
b4f48b63 PM |
373 | } |
374 | ||
817929ec PM |
375 | /* |
376 | * refcounted get/put for css_set objects | |
377 | */ | |
378 | static inline void get_css_set(struct css_set *cg) | |
379 | { | |
146aa1bd | 380 | atomic_inc(&cg->refcount); |
817929ec PM |
381 | } |
382 | ||
383 | static inline void put_css_set(struct css_set *cg) | |
384 | { | |
146aa1bd | 385 | __put_css_set(cg, 0); |
817929ec PM |
386 | } |
387 | ||
81a6a5cd PM |
388 | static inline void put_css_set_taskexit(struct css_set *cg) |
389 | { | |
146aa1bd | 390 | __put_css_set(cg, 1); |
81a6a5cd PM |
391 | } |
392 | ||
7717f7ba PM |
393 | /* |
394 | * compare_css_sets - helper function for find_existing_css_set(). | |
395 | * @cg: candidate css_set being tested | |
396 | * @old_cg: existing css_set for a task | |
397 | * @new_cgrp: cgroup that's being entered by the task | |
398 | * @template: desired set of css pointers in css_set (pre-calculated) | |
399 | * | |
400 | * Returns true if "cg" matches "old_cg" except for the hierarchy | |
401 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". | |
402 | */ | |
403 | static bool compare_css_sets(struct css_set *cg, | |
404 | struct css_set *old_cg, | |
405 | struct cgroup *new_cgrp, | |
406 | struct cgroup_subsys_state *template[]) | |
407 | { | |
408 | struct list_head *l1, *l2; | |
409 | ||
410 | if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { | |
411 | /* Not all subsystems matched */ | |
412 | return false; | |
413 | } | |
414 | ||
415 | /* | |
416 | * Compare cgroup pointers in order to distinguish between | |
417 | * different cgroups in heirarchies with no subsystems. We | |
418 | * could get by with just this check alone (and skip the | |
419 | * memcmp above) but on most setups the memcmp check will | |
420 | * avoid the need for this more expensive check on almost all | |
421 | * candidates. | |
422 | */ | |
423 | ||
424 | l1 = &cg->cg_links; | |
425 | l2 = &old_cg->cg_links; | |
426 | while (1) { | |
427 | struct cg_cgroup_link *cgl1, *cgl2; | |
428 | struct cgroup *cg1, *cg2; | |
429 | ||
430 | l1 = l1->next; | |
431 | l2 = l2->next; | |
432 | /* See if we reached the end - both lists are equal length. */ | |
433 | if (l1 == &cg->cg_links) { | |
434 | BUG_ON(l2 != &old_cg->cg_links); | |
435 | break; | |
436 | } else { | |
437 | BUG_ON(l2 == &old_cg->cg_links); | |
438 | } | |
439 | /* Locate the cgroups associated with these links. */ | |
440 | cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); | |
441 | cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); | |
442 | cg1 = cgl1->cgrp; | |
443 | cg2 = cgl2->cgrp; | |
444 | /* Hierarchies should be linked in the same order. */ | |
445 | BUG_ON(cg1->root != cg2->root); | |
446 | ||
447 | /* | |
448 | * If this hierarchy is the hierarchy of the cgroup | |
449 | * that's changing, then we need to check that this | |
450 | * css_set points to the new cgroup; if it's any other | |
451 | * hierarchy, then this css_set should point to the | |
452 | * same cgroup as the old css_set. | |
453 | */ | |
454 | if (cg1->root == new_cgrp->root) { | |
455 | if (cg1 != new_cgrp) | |
456 | return false; | |
457 | } else { | |
458 | if (cg1 != cg2) | |
459 | return false; | |
460 | } | |
461 | } | |
462 | return true; | |
463 | } | |
464 | ||
817929ec PM |
465 | /* |
466 | * find_existing_css_set() is a helper for | |
467 | * find_css_set(), and checks to see whether an existing | |
472b1053 | 468 | * css_set is suitable. |
817929ec PM |
469 | * |
470 | * oldcg: the cgroup group that we're using before the cgroup | |
471 | * transition | |
472 | * | |
bd89aabc | 473 | * cgrp: the cgroup that we're moving into |
817929ec PM |
474 | * |
475 | * template: location in which to build the desired set of subsystem | |
476 | * state objects for the new cgroup group | |
477 | */ | |
817929ec PM |
478 | static struct css_set *find_existing_css_set( |
479 | struct css_set *oldcg, | |
bd89aabc | 480 | struct cgroup *cgrp, |
817929ec | 481 | struct cgroup_subsys_state *template[]) |
b4f48b63 PM |
482 | { |
483 | int i; | |
bd89aabc | 484 | struct cgroupfs_root *root = cgrp->root; |
472b1053 LZ |
485 | struct hlist_head *hhead; |
486 | struct hlist_node *node; | |
487 | struct css_set *cg; | |
817929ec | 488 | |
aae8aab4 BB |
489 | /* |
490 | * Build the set of subsystem state objects that we want to see in the | |
491 | * new css_set. while subsystems can change globally, the entries here | |
492 | * won't change, so no need for locking. | |
493 | */ | |
817929ec | 494 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
8d53d55d | 495 | if (root->subsys_bits & (1UL << i)) { |
817929ec PM |
496 | /* Subsystem is in this hierarchy. So we want |
497 | * the subsystem state from the new | |
498 | * cgroup */ | |
bd89aabc | 499 | template[i] = cgrp->subsys[i]; |
817929ec PM |
500 | } else { |
501 | /* Subsystem is not in this hierarchy, so we | |
502 | * don't want to change the subsystem state */ | |
503 | template[i] = oldcg->subsys[i]; | |
504 | } | |
505 | } | |
506 | ||
472b1053 LZ |
507 | hhead = css_set_hash(template); |
508 | hlist_for_each_entry(cg, node, hhead, hlist) { | |
7717f7ba PM |
509 | if (!compare_css_sets(cg, oldcg, cgrp, template)) |
510 | continue; | |
511 | ||
512 | /* This css_set matches what we need */ | |
513 | return cg; | |
472b1053 | 514 | } |
817929ec PM |
515 | |
516 | /* No existing cgroup group matched */ | |
517 | return NULL; | |
518 | } | |
519 | ||
36553434 LZ |
520 | static void free_cg_links(struct list_head *tmp) |
521 | { | |
522 | struct cg_cgroup_link *link; | |
523 | struct cg_cgroup_link *saved_link; | |
524 | ||
525 | list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { | |
526 | list_del(&link->cgrp_link_list); | |
527 | kfree(link); | |
528 | } | |
529 | } | |
530 | ||
817929ec PM |
531 | /* |
532 | * allocate_cg_links() allocates "count" cg_cgroup_link structures | |
bd89aabc | 533 | * and chains them on tmp through their cgrp_link_list fields. Returns 0 on |
817929ec PM |
534 | * success or a negative error |
535 | */ | |
817929ec PM |
536 | static int allocate_cg_links(int count, struct list_head *tmp) |
537 | { | |
538 | struct cg_cgroup_link *link; | |
539 | int i; | |
540 | INIT_LIST_HEAD(tmp); | |
541 | for (i = 0; i < count; i++) { | |
542 | link = kmalloc(sizeof(*link), GFP_KERNEL); | |
543 | if (!link) { | |
36553434 | 544 | free_cg_links(tmp); |
817929ec PM |
545 | return -ENOMEM; |
546 | } | |
bd89aabc | 547 | list_add(&link->cgrp_link_list, tmp); |
817929ec PM |
548 | } |
549 | return 0; | |
550 | } | |
551 | ||
c12f65d4 LZ |
552 | /** |
553 | * link_css_set - a helper function to link a css_set to a cgroup | |
554 | * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() | |
555 | * @cg: the css_set to be linked | |
556 | * @cgrp: the destination cgroup | |
557 | */ | |
558 | static void link_css_set(struct list_head *tmp_cg_links, | |
559 | struct css_set *cg, struct cgroup *cgrp) | |
560 | { | |
561 | struct cg_cgroup_link *link; | |
562 | ||
563 | BUG_ON(list_empty(tmp_cg_links)); | |
564 | link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, | |
565 | cgrp_link_list); | |
566 | link->cg = cg; | |
7717f7ba | 567 | link->cgrp = cgrp; |
2c6ab6d2 | 568 | atomic_inc(&cgrp->count); |
c12f65d4 | 569 | list_move(&link->cgrp_link_list, &cgrp->css_sets); |
7717f7ba PM |
570 | /* |
571 | * Always add links to the tail of the list so that the list | |
572 | * is sorted by order of hierarchy creation | |
573 | */ | |
574 | list_add_tail(&link->cg_link_list, &cg->cg_links); | |
c12f65d4 LZ |
575 | } |
576 | ||
817929ec PM |
577 | /* |
578 | * find_css_set() takes an existing cgroup group and a | |
579 | * cgroup object, and returns a css_set object that's | |
580 | * equivalent to the old group, but with the given cgroup | |
581 | * substituted into the appropriate hierarchy. Must be called with | |
582 | * cgroup_mutex held | |
583 | */ | |
817929ec | 584 | static struct css_set *find_css_set( |
bd89aabc | 585 | struct css_set *oldcg, struct cgroup *cgrp) |
817929ec PM |
586 | { |
587 | struct css_set *res; | |
588 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; | |
817929ec PM |
589 | |
590 | struct list_head tmp_cg_links; | |
817929ec | 591 | |
472b1053 | 592 | struct hlist_head *hhead; |
7717f7ba | 593 | struct cg_cgroup_link *link; |
472b1053 | 594 | |
817929ec PM |
595 | /* First see if we already have a cgroup group that matches |
596 | * the desired set */ | |
7e9abd89 | 597 | read_lock(&css_set_lock); |
bd89aabc | 598 | res = find_existing_css_set(oldcg, cgrp, template); |
817929ec PM |
599 | if (res) |
600 | get_css_set(res); | |
7e9abd89 | 601 | read_unlock(&css_set_lock); |
817929ec PM |
602 | |
603 | if (res) | |
604 | return res; | |
605 | ||
606 | res = kmalloc(sizeof(*res), GFP_KERNEL); | |
607 | if (!res) | |
608 | return NULL; | |
609 | ||
610 | /* Allocate all the cg_cgroup_link objects that we'll need */ | |
611 | if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { | |
612 | kfree(res); | |
613 | return NULL; | |
614 | } | |
615 | ||
146aa1bd | 616 | atomic_set(&res->refcount, 1); |
817929ec PM |
617 | INIT_LIST_HEAD(&res->cg_links); |
618 | INIT_LIST_HEAD(&res->tasks); | |
472b1053 | 619 | INIT_HLIST_NODE(&res->hlist); |
817929ec PM |
620 | |
621 | /* Copy the set of subsystem state objects generated in | |
622 | * find_existing_css_set() */ | |
623 | memcpy(res->subsys, template, sizeof(res->subsys)); | |
624 | ||
625 | write_lock(&css_set_lock); | |
626 | /* Add reference counts and links from the new css_set. */ | |
7717f7ba PM |
627 | list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { |
628 | struct cgroup *c = link->cgrp; | |
629 | if (c->root == cgrp->root) | |
630 | c = cgrp; | |
631 | link_css_set(&tmp_cg_links, res, c); | |
632 | } | |
817929ec PM |
633 | |
634 | BUG_ON(!list_empty(&tmp_cg_links)); | |
635 | ||
817929ec | 636 | css_set_count++; |
472b1053 LZ |
637 | |
638 | /* Add this cgroup group to the hash table */ | |
639 | hhead = css_set_hash(res->subsys); | |
640 | hlist_add_head(&res->hlist, hhead); | |
641 | ||
817929ec PM |
642 | write_unlock(&css_set_lock); |
643 | ||
644 | return res; | |
b4f48b63 PM |
645 | } |
646 | ||
7717f7ba PM |
647 | /* |
648 | * Return the cgroup for "task" from the given hierarchy. Must be | |
649 | * called with cgroup_mutex held. | |
650 | */ | |
651 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
652 | struct cgroupfs_root *root) | |
653 | { | |
654 | struct css_set *css; | |
655 | struct cgroup *res = NULL; | |
656 | ||
657 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
658 | read_lock(&css_set_lock); | |
659 | /* | |
660 | * No need to lock the task - since we hold cgroup_mutex the | |
661 | * task can't change groups, so the only thing that can happen | |
662 | * is that it exits and its css is set back to init_css_set. | |
663 | */ | |
664 | css = task->cgroups; | |
665 | if (css == &init_css_set) { | |
666 | res = &root->top_cgroup; | |
667 | } else { | |
668 | struct cg_cgroup_link *link; | |
669 | list_for_each_entry(link, &css->cg_links, cg_link_list) { | |
670 | struct cgroup *c = link->cgrp; | |
671 | if (c->root == root) { | |
672 | res = c; | |
673 | break; | |
674 | } | |
675 | } | |
676 | } | |
677 | read_unlock(&css_set_lock); | |
678 | BUG_ON(!res); | |
679 | return res; | |
680 | } | |
681 | ||
ddbcc7e8 PM |
682 | /* |
683 | * There is one global cgroup mutex. We also require taking | |
684 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
685 | * See "The task_lock() exception", at the end of this comment. | |
686 | * | |
687 | * A task must hold cgroup_mutex to modify cgroups. | |
688 | * | |
689 | * Any task can increment and decrement the count field without lock. | |
690 | * So in general, code holding cgroup_mutex can't rely on the count | |
691 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 692 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
693 | * means that no tasks are currently attached, therefore there is no |
694 | * way a task attached to that cgroup can fork (the other way to | |
695 | * increment the count). So code holding cgroup_mutex can safely | |
696 | * assume that if the count is zero, it will stay zero. Similarly, if | |
697 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
698 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
699 | * needs that mutex. | |
700 | * | |
ddbcc7e8 PM |
701 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
702 | * (usually) take cgroup_mutex. These are the two most performance | |
703 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
704 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
705 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
706 | * to the release agent with the name of the cgroup (path relative to |
707 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
708 | * |
709 | * A cgroup can only be deleted if both its 'count' of using tasks | |
710 | * is zero, and its list of 'children' cgroups is empty. Since all | |
711 | * tasks in the system use _some_ cgroup, and since there is always at | |
712 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
713 | * always has either children cgroups and/or using tasks. So we don't | |
714 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
715 | * | |
716 | * The task_lock() exception | |
717 | * | |
718 | * The need for this exception arises from the action of | |
956db3ca | 719 | * cgroup_attach_task(), which overwrites one tasks cgroup pointer with |
a043e3b2 | 720 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
721 | * several performance critical places that need to reference |
722 | * task->cgroup without the expense of grabbing a system global | |
723 | * mutex. Therefore except as noted below, when dereferencing or, as | |
956db3ca | 724 | * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use |
ddbcc7e8 PM |
725 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
726 | * the task_struct routinely used for such matters. | |
727 | * | |
728 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 729 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
730 | */ |
731 | ||
ddbcc7e8 PM |
732 | /** |
733 | * cgroup_lock - lock out any changes to cgroup structures | |
734 | * | |
735 | */ | |
ddbcc7e8 PM |
736 | void cgroup_lock(void) |
737 | { | |
738 | mutex_lock(&cgroup_mutex); | |
739 | } | |
67523c48 | 740 | EXPORT_SYMBOL_GPL(cgroup_lock); |
ddbcc7e8 PM |
741 | |
742 | /** | |
743 | * cgroup_unlock - release lock on cgroup changes | |
744 | * | |
745 | * Undo the lock taken in a previous cgroup_lock() call. | |
746 | */ | |
ddbcc7e8 PM |
747 | void cgroup_unlock(void) |
748 | { | |
749 | mutex_unlock(&cgroup_mutex); | |
750 | } | |
67523c48 | 751 | EXPORT_SYMBOL_GPL(cgroup_unlock); |
ddbcc7e8 PM |
752 | |
753 | /* | |
754 | * A couple of forward declarations required, due to cyclic reference loop: | |
755 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
756 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
757 | * -> cgroup_mkdir. | |
758 | */ | |
759 | ||
760 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode); | |
c72a04e3 | 761 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, struct nameidata *); |
ddbcc7e8 | 762 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
bd89aabc | 763 | static int cgroup_populate_dir(struct cgroup *cgrp); |
6e1d5dcc | 764 | static const struct inode_operations cgroup_dir_inode_operations; |
828c0950 | 765 | static const struct file_operations proc_cgroupstats_operations; |
a424316c PM |
766 | |
767 | static struct backing_dev_info cgroup_backing_dev_info = { | |
d993831f | 768 | .name = "cgroup", |
e4ad08fe | 769 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
a424316c | 770 | }; |
ddbcc7e8 | 771 | |
38460b48 KH |
772 | static int alloc_css_id(struct cgroup_subsys *ss, |
773 | struct cgroup *parent, struct cgroup *child); | |
774 | ||
ddbcc7e8 PM |
775 | static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb) |
776 | { | |
777 | struct inode *inode = new_inode(sb); | |
ddbcc7e8 PM |
778 | |
779 | if (inode) { | |
85fe4025 | 780 | inode->i_ino = get_next_ino(); |
ddbcc7e8 | 781 | inode->i_mode = mode; |
76aac0e9 DH |
782 | inode->i_uid = current_fsuid(); |
783 | inode->i_gid = current_fsgid(); | |
ddbcc7e8 PM |
784 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
785 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
786 | } | |
787 | return inode; | |
788 | } | |
789 | ||
4fca88c8 KH |
790 | /* |
791 | * Call subsys's pre_destroy handler. | |
792 | * This is called before css refcnt check. | |
793 | */ | |
ec64f515 | 794 | static int cgroup_call_pre_destroy(struct cgroup *cgrp) |
4fca88c8 KH |
795 | { |
796 | struct cgroup_subsys *ss; | |
ec64f515 KH |
797 | int ret = 0; |
798 | ||
4fca88c8 | 799 | for_each_subsys(cgrp->root, ss) |
ec64f515 KH |
800 | if (ss->pre_destroy) { |
801 | ret = ss->pre_destroy(ss, cgrp); | |
802 | if (ret) | |
4ab78683 | 803 | break; |
ec64f515 | 804 | } |
0dea1168 | 805 | |
ec64f515 | 806 | return ret; |
4fca88c8 KH |
807 | } |
808 | ||
ddbcc7e8 PM |
809 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
810 | { | |
811 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
812 | if (S_ISDIR(inode->i_mode)) { | |
bd89aabc | 813 | struct cgroup *cgrp = dentry->d_fsdata; |
8dc4f3e1 | 814 | struct cgroup_subsys *ss; |
bd89aabc | 815 | BUG_ON(!(cgroup_is_removed(cgrp))); |
81a6a5cd PM |
816 | /* It's possible for external users to be holding css |
817 | * reference counts on a cgroup; css_put() needs to | |
818 | * be able to access the cgroup after decrementing | |
819 | * the reference count in order to know if it needs to | |
820 | * queue the cgroup to be handled by the release | |
821 | * agent */ | |
822 | synchronize_rcu(); | |
8dc4f3e1 PM |
823 | |
824 | mutex_lock(&cgroup_mutex); | |
825 | /* | |
826 | * Release the subsystem state objects. | |
827 | */ | |
75139b82 LZ |
828 | for_each_subsys(cgrp->root, ss) |
829 | ss->destroy(ss, cgrp); | |
8dc4f3e1 PM |
830 | |
831 | cgrp->root->number_of_cgroups--; | |
832 | mutex_unlock(&cgroup_mutex); | |
833 | ||
a47295e6 PM |
834 | /* |
835 | * Drop the active superblock reference that we took when we | |
836 | * created the cgroup | |
837 | */ | |
8dc4f3e1 PM |
838 | deactivate_super(cgrp->root->sb); |
839 | ||
72a8cb30 BB |
840 | /* |
841 | * if we're getting rid of the cgroup, refcount should ensure | |
842 | * that there are no pidlists left. | |
843 | */ | |
844 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
845 | ||
f2da1c40 | 846 | kfree_rcu(cgrp, rcu_head); |
ddbcc7e8 PM |
847 | } |
848 | iput(inode); | |
849 | } | |
850 | ||
c72a04e3 AV |
851 | static int cgroup_delete(const struct dentry *d) |
852 | { | |
853 | return 1; | |
854 | } | |
855 | ||
ddbcc7e8 PM |
856 | static void remove_dir(struct dentry *d) |
857 | { | |
858 | struct dentry *parent = dget(d->d_parent); | |
859 | ||
860 | d_delete(d); | |
861 | simple_rmdir(parent->d_inode, d); | |
862 | dput(parent); | |
863 | } | |
864 | ||
865 | static void cgroup_clear_directory(struct dentry *dentry) | |
866 | { | |
867 | struct list_head *node; | |
868 | ||
869 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
2fd6b7f5 | 870 | spin_lock(&dentry->d_lock); |
ddbcc7e8 PM |
871 | node = dentry->d_subdirs.next; |
872 | while (node != &dentry->d_subdirs) { | |
873 | struct dentry *d = list_entry(node, struct dentry, d_u.d_child); | |
2fd6b7f5 NP |
874 | |
875 | spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); | |
ddbcc7e8 PM |
876 | list_del_init(node); |
877 | if (d->d_inode) { | |
878 | /* This should never be called on a cgroup | |
879 | * directory with child cgroups */ | |
880 | BUG_ON(d->d_inode->i_mode & S_IFDIR); | |
dc0474be | 881 | dget_dlock(d); |
2fd6b7f5 NP |
882 | spin_unlock(&d->d_lock); |
883 | spin_unlock(&dentry->d_lock); | |
ddbcc7e8 PM |
884 | d_delete(d); |
885 | simple_unlink(dentry->d_inode, d); | |
886 | dput(d); | |
2fd6b7f5 NP |
887 | spin_lock(&dentry->d_lock); |
888 | } else | |
889 | spin_unlock(&d->d_lock); | |
ddbcc7e8 PM |
890 | node = dentry->d_subdirs.next; |
891 | } | |
2fd6b7f5 | 892 | spin_unlock(&dentry->d_lock); |
ddbcc7e8 PM |
893 | } |
894 | ||
895 | /* | |
896 | * NOTE : the dentry must have been dget()'ed | |
897 | */ | |
898 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
899 | { | |
2fd6b7f5 NP |
900 | struct dentry *parent; |
901 | ||
ddbcc7e8 PM |
902 | cgroup_clear_directory(dentry); |
903 | ||
2fd6b7f5 NP |
904 | parent = dentry->d_parent; |
905 | spin_lock(&parent->d_lock); | |
3ec762ad | 906 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
ddbcc7e8 | 907 | list_del_init(&dentry->d_u.d_child); |
2fd6b7f5 NP |
908 | spin_unlock(&dentry->d_lock); |
909 | spin_unlock(&parent->d_lock); | |
ddbcc7e8 PM |
910 | remove_dir(dentry); |
911 | } | |
912 | ||
ec64f515 KH |
913 | /* |
914 | * A queue for waiters to do rmdir() cgroup. A tasks will sleep when | |
915 | * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some | |
916 | * reference to css->refcnt. In general, this refcnt is expected to goes down | |
917 | * to zero, soon. | |
918 | * | |
88703267 | 919 | * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex; |
ec64f515 KH |
920 | */ |
921 | DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq); | |
922 | ||
88703267 | 923 | static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp) |
ec64f515 | 924 | { |
88703267 | 925 | if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))) |
ec64f515 KH |
926 | wake_up_all(&cgroup_rmdir_waitq); |
927 | } | |
928 | ||
88703267 KH |
929 | void cgroup_exclude_rmdir(struct cgroup_subsys_state *css) |
930 | { | |
931 | css_get(css); | |
932 | } | |
933 | ||
934 | void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css) | |
935 | { | |
936 | cgroup_wakeup_rmdir_waiter(css->cgroup); | |
937 | css_put(css); | |
938 | } | |
939 | ||
aae8aab4 | 940 | /* |
cf5d5941 BB |
941 | * Call with cgroup_mutex held. Drops reference counts on modules, including |
942 | * any duplicate ones that parse_cgroupfs_options took. If this function | |
943 | * returns an error, no reference counts are touched. | |
aae8aab4 | 944 | */ |
ddbcc7e8 PM |
945 | static int rebind_subsystems(struct cgroupfs_root *root, |
946 | unsigned long final_bits) | |
947 | { | |
948 | unsigned long added_bits, removed_bits; | |
bd89aabc | 949 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
950 | int i; |
951 | ||
aae8aab4 BB |
952 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
953 | ||
ddbcc7e8 PM |
954 | removed_bits = root->actual_subsys_bits & ~final_bits; |
955 | added_bits = final_bits & ~root->actual_subsys_bits; | |
956 | /* Check that any added subsystems are currently free */ | |
957 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
8d53d55d | 958 | unsigned long bit = 1UL << i; |
ddbcc7e8 PM |
959 | struct cgroup_subsys *ss = subsys[i]; |
960 | if (!(bit & added_bits)) | |
961 | continue; | |
aae8aab4 BB |
962 | /* |
963 | * Nobody should tell us to do a subsys that doesn't exist: | |
964 | * parse_cgroupfs_options should catch that case and refcounts | |
965 | * ensure that subsystems won't disappear once selected. | |
966 | */ | |
967 | BUG_ON(ss == NULL); | |
ddbcc7e8 PM |
968 | if (ss->root != &rootnode) { |
969 | /* Subsystem isn't free */ | |
970 | return -EBUSY; | |
971 | } | |
972 | } | |
973 | ||
974 | /* Currently we don't handle adding/removing subsystems when | |
975 | * any child cgroups exist. This is theoretically supportable | |
976 | * but involves complex error handling, so it's being left until | |
977 | * later */ | |
307257cf | 978 | if (root->number_of_cgroups > 1) |
ddbcc7e8 PM |
979 | return -EBUSY; |
980 | ||
981 | /* Process each subsystem */ | |
982 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
983 | struct cgroup_subsys *ss = subsys[i]; | |
984 | unsigned long bit = 1UL << i; | |
985 | if (bit & added_bits) { | |
986 | /* We're binding this subsystem to this hierarchy */ | |
aae8aab4 | 987 | BUG_ON(ss == NULL); |
bd89aabc | 988 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
989 | BUG_ON(!dummytop->subsys[i]); |
990 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); | |
999cd8a4 | 991 | mutex_lock(&ss->hierarchy_mutex); |
bd89aabc PM |
992 | cgrp->subsys[i] = dummytop->subsys[i]; |
993 | cgrp->subsys[i]->cgroup = cgrp; | |
33a68ac1 | 994 | list_move(&ss->sibling, &root->subsys_list); |
b2aa30f7 | 995 | ss->root = root; |
ddbcc7e8 | 996 | if (ss->bind) |
bd89aabc | 997 | ss->bind(ss, cgrp); |
999cd8a4 | 998 | mutex_unlock(&ss->hierarchy_mutex); |
cf5d5941 | 999 | /* refcount was already taken, and we're keeping it */ |
ddbcc7e8 PM |
1000 | } else if (bit & removed_bits) { |
1001 | /* We're removing this subsystem */ | |
aae8aab4 | 1002 | BUG_ON(ss == NULL); |
bd89aabc PM |
1003 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
1004 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); | |
999cd8a4 | 1005 | mutex_lock(&ss->hierarchy_mutex); |
ddbcc7e8 PM |
1006 | if (ss->bind) |
1007 | ss->bind(ss, dummytop); | |
1008 | dummytop->subsys[i]->cgroup = dummytop; | |
bd89aabc | 1009 | cgrp->subsys[i] = NULL; |
b2aa30f7 | 1010 | subsys[i]->root = &rootnode; |
33a68ac1 | 1011 | list_move(&ss->sibling, &rootnode.subsys_list); |
999cd8a4 | 1012 | mutex_unlock(&ss->hierarchy_mutex); |
cf5d5941 BB |
1013 | /* subsystem is now free - drop reference on module */ |
1014 | module_put(ss->module); | |
ddbcc7e8 PM |
1015 | } else if (bit & final_bits) { |
1016 | /* Subsystem state should already exist */ | |
aae8aab4 | 1017 | BUG_ON(ss == NULL); |
bd89aabc | 1018 | BUG_ON(!cgrp->subsys[i]); |
cf5d5941 BB |
1019 | /* |
1020 | * a refcount was taken, but we already had one, so | |
1021 | * drop the extra reference. | |
1022 | */ | |
1023 | module_put(ss->module); | |
1024 | #ifdef CONFIG_MODULE_UNLOAD | |
1025 | BUG_ON(ss->module && !module_refcount(ss->module)); | |
1026 | #endif | |
ddbcc7e8 PM |
1027 | } else { |
1028 | /* Subsystem state shouldn't exist */ | |
bd89aabc | 1029 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1030 | } |
1031 | } | |
1032 | root->subsys_bits = root->actual_subsys_bits = final_bits; | |
1033 | synchronize_rcu(); | |
1034 | ||
1035 | return 0; | |
1036 | } | |
1037 | ||
1038 | static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) | |
1039 | { | |
1040 | struct cgroupfs_root *root = vfs->mnt_sb->s_fs_info; | |
1041 | struct cgroup_subsys *ss; | |
1042 | ||
1043 | mutex_lock(&cgroup_mutex); | |
1044 | for_each_subsys(root, ss) | |
1045 | seq_printf(seq, ",%s", ss->name); | |
1046 | if (test_bit(ROOT_NOPREFIX, &root->flags)) | |
1047 | seq_puts(seq, ",noprefix"); | |
81a6a5cd PM |
1048 | if (strlen(root->release_agent_path)) |
1049 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
97978e6d DL |
1050 | if (clone_children(&root->top_cgroup)) |
1051 | seq_puts(seq, ",clone_children"); | |
c6d57f33 PM |
1052 | if (strlen(root->name)) |
1053 | seq_printf(seq, ",name=%s", root->name); | |
ddbcc7e8 PM |
1054 | mutex_unlock(&cgroup_mutex); |
1055 | return 0; | |
1056 | } | |
1057 | ||
1058 | struct cgroup_sb_opts { | |
1059 | unsigned long subsys_bits; | |
1060 | unsigned long flags; | |
81a6a5cd | 1061 | char *release_agent; |
97978e6d | 1062 | bool clone_children; |
c6d57f33 | 1063 | char *name; |
2c6ab6d2 PM |
1064 | /* User explicitly requested empty subsystem */ |
1065 | bool none; | |
c6d57f33 PM |
1066 | |
1067 | struct cgroupfs_root *new_root; | |
2c6ab6d2 | 1068 | |
ddbcc7e8 PM |
1069 | }; |
1070 | ||
aae8aab4 BB |
1071 | /* |
1072 | * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call | |
cf5d5941 BB |
1073 | * with cgroup_mutex held to protect the subsys[] array. This function takes |
1074 | * refcounts on subsystems to be used, unless it returns error, in which case | |
1075 | * no refcounts are taken. | |
aae8aab4 | 1076 | */ |
cf5d5941 | 1077 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1078 | { |
32a8cf23 DL |
1079 | char *token, *o = data; |
1080 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1081 | unsigned long mask = (unsigned long)-1; |
cf5d5941 BB |
1082 | int i; |
1083 | bool module_pin_failed = false; | |
f9ab5b5b | 1084 | |
aae8aab4 BB |
1085 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1086 | ||
f9ab5b5b LZ |
1087 | #ifdef CONFIG_CPUSETS |
1088 | mask = ~(1UL << cpuset_subsys_id); | |
1089 | #endif | |
ddbcc7e8 | 1090 | |
c6d57f33 | 1091 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1092 | |
1093 | while ((token = strsep(&o, ",")) != NULL) { | |
1094 | if (!*token) | |
1095 | return -EINVAL; | |
32a8cf23 | 1096 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1097 | /* Explicitly have no subsystems */ |
1098 | opts->none = true; | |
32a8cf23 DL |
1099 | continue; |
1100 | } | |
1101 | if (!strcmp(token, "all")) { | |
1102 | /* Mutually exclusive option 'all' + subsystem name */ | |
1103 | if (one_ss) | |
1104 | return -EINVAL; | |
1105 | all_ss = true; | |
1106 | continue; | |
1107 | } | |
1108 | if (!strcmp(token, "noprefix")) { | |
ddbcc7e8 | 1109 | set_bit(ROOT_NOPREFIX, &opts->flags); |
32a8cf23 DL |
1110 | continue; |
1111 | } | |
1112 | if (!strcmp(token, "clone_children")) { | |
97978e6d | 1113 | opts->clone_children = true; |
32a8cf23 DL |
1114 | continue; |
1115 | } | |
1116 | if (!strncmp(token, "release_agent=", 14)) { | |
81a6a5cd PM |
1117 | /* Specifying two release agents is forbidden */ |
1118 | if (opts->release_agent) | |
1119 | return -EINVAL; | |
c6d57f33 | 1120 | opts->release_agent = |
e400c285 | 1121 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1122 | if (!opts->release_agent) |
1123 | return -ENOMEM; | |
32a8cf23 DL |
1124 | continue; |
1125 | } | |
1126 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1127 | const char *name = token + 5; |
1128 | /* Can't specify an empty name */ | |
1129 | if (!strlen(name)) | |
1130 | return -EINVAL; | |
1131 | /* Must match [\w.-]+ */ | |
1132 | for (i = 0; i < strlen(name); i++) { | |
1133 | char c = name[i]; | |
1134 | if (isalnum(c)) | |
1135 | continue; | |
1136 | if ((c == '.') || (c == '-') || (c == '_')) | |
1137 | continue; | |
1138 | return -EINVAL; | |
1139 | } | |
1140 | /* Specifying two names is forbidden */ | |
1141 | if (opts->name) | |
1142 | return -EINVAL; | |
1143 | opts->name = kstrndup(name, | |
e400c285 | 1144 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1145 | GFP_KERNEL); |
1146 | if (!opts->name) | |
1147 | return -ENOMEM; | |
32a8cf23 DL |
1148 | |
1149 | continue; | |
1150 | } | |
1151 | ||
1152 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1153 | struct cgroup_subsys *ss = subsys[i]; | |
1154 | if (ss == NULL) | |
1155 | continue; | |
1156 | if (strcmp(token, ss->name)) | |
1157 | continue; | |
1158 | if (ss->disabled) | |
1159 | continue; | |
1160 | ||
1161 | /* Mutually exclusive option 'all' + subsystem name */ | |
1162 | if (all_ss) | |
1163 | return -EINVAL; | |
1164 | set_bit(i, &opts->subsys_bits); | |
1165 | one_ss = true; | |
1166 | ||
1167 | break; | |
1168 | } | |
1169 | if (i == CGROUP_SUBSYS_COUNT) | |
1170 | return -ENOENT; | |
1171 | } | |
1172 | ||
1173 | /* | |
1174 | * If the 'all' option was specified select all the subsystems, | |
1175 | * otherwise 'all, 'none' and a subsystem name options were not | |
1176 | * specified, let's default to 'all' | |
1177 | */ | |
1178 | if (all_ss || (!all_ss && !one_ss && !opts->none)) { | |
1179 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1180 | struct cgroup_subsys *ss = subsys[i]; | |
1181 | if (ss == NULL) | |
1182 | continue; | |
1183 | if (ss->disabled) | |
1184 | continue; | |
1185 | set_bit(i, &opts->subsys_bits); | |
ddbcc7e8 PM |
1186 | } |
1187 | } | |
1188 | ||
2c6ab6d2 PM |
1189 | /* Consistency checks */ |
1190 | ||
f9ab5b5b LZ |
1191 | /* |
1192 | * Option noprefix was introduced just for backward compatibility | |
1193 | * with the old cpuset, so we allow noprefix only if mounting just | |
1194 | * the cpuset subsystem. | |
1195 | */ | |
1196 | if (test_bit(ROOT_NOPREFIX, &opts->flags) && | |
1197 | (opts->subsys_bits & mask)) | |
1198 | return -EINVAL; | |
1199 | ||
2c6ab6d2 PM |
1200 | |
1201 | /* Can't specify "none" and some subsystems */ | |
1202 | if (opts->subsys_bits && opts->none) | |
1203 | return -EINVAL; | |
1204 | ||
1205 | /* | |
1206 | * We either have to specify by name or by subsystems. (So all | |
1207 | * empty hierarchies must have a name). | |
1208 | */ | |
c6d57f33 | 1209 | if (!opts->subsys_bits && !opts->name) |
ddbcc7e8 PM |
1210 | return -EINVAL; |
1211 | ||
cf5d5941 BB |
1212 | /* |
1213 | * Grab references on all the modules we'll need, so the subsystems | |
1214 | * don't dance around before rebind_subsystems attaches them. This may | |
1215 | * take duplicate reference counts on a subsystem that's already used, | |
1216 | * but rebind_subsystems handles this case. | |
1217 | */ | |
1218 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
1219 | unsigned long bit = 1UL << i; | |
1220 | ||
1221 | if (!(bit & opts->subsys_bits)) | |
1222 | continue; | |
1223 | if (!try_module_get(subsys[i]->module)) { | |
1224 | module_pin_failed = true; | |
1225 | break; | |
1226 | } | |
1227 | } | |
1228 | if (module_pin_failed) { | |
1229 | /* | |
1230 | * oops, one of the modules was going away. this means that we | |
1231 | * raced with a module_delete call, and to the user this is | |
1232 | * essentially a "subsystem doesn't exist" case. | |
1233 | */ | |
1234 | for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) { | |
1235 | /* drop refcounts only on the ones we took */ | |
1236 | unsigned long bit = 1UL << i; | |
1237 | ||
1238 | if (!(bit & opts->subsys_bits)) | |
1239 | continue; | |
1240 | module_put(subsys[i]->module); | |
1241 | } | |
1242 | return -ENOENT; | |
1243 | } | |
1244 | ||
ddbcc7e8 PM |
1245 | return 0; |
1246 | } | |
1247 | ||
cf5d5941 BB |
1248 | static void drop_parsed_module_refcounts(unsigned long subsys_bits) |
1249 | { | |
1250 | int i; | |
1251 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
1252 | unsigned long bit = 1UL << i; | |
1253 | ||
1254 | if (!(bit & subsys_bits)) | |
1255 | continue; | |
1256 | module_put(subsys[i]->module); | |
1257 | } | |
1258 | } | |
1259 | ||
ddbcc7e8 PM |
1260 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) |
1261 | { | |
1262 | int ret = 0; | |
1263 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1264 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
1265 | struct cgroup_sb_opts opts; |
1266 | ||
bd89aabc | 1267 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
1268 | mutex_lock(&cgroup_mutex); |
1269 | ||
1270 | /* See what subsystems are wanted */ | |
1271 | ret = parse_cgroupfs_options(data, &opts); | |
1272 | if (ret) | |
1273 | goto out_unlock; | |
1274 | ||
cf5d5941 BB |
1275 | /* Don't allow flags or name to change at remount */ |
1276 | if (opts.flags != root->flags || | |
1277 | (opts.name && strcmp(opts.name, root->name))) { | |
c6d57f33 | 1278 | ret = -EINVAL; |
cf5d5941 | 1279 | drop_parsed_module_refcounts(opts.subsys_bits); |
c6d57f33 PM |
1280 | goto out_unlock; |
1281 | } | |
1282 | ||
ddbcc7e8 | 1283 | ret = rebind_subsystems(root, opts.subsys_bits); |
cf5d5941 BB |
1284 | if (ret) { |
1285 | drop_parsed_module_refcounts(opts.subsys_bits); | |
0670e08b | 1286 | goto out_unlock; |
cf5d5941 | 1287 | } |
ddbcc7e8 PM |
1288 | |
1289 | /* (re)populate subsystem files */ | |
0670e08b | 1290 | cgroup_populate_dir(cgrp); |
ddbcc7e8 | 1291 | |
81a6a5cd PM |
1292 | if (opts.release_agent) |
1293 | strcpy(root->release_agent_path, opts.release_agent); | |
ddbcc7e8 | 1294 | out_unlock: |
66bdc9cf | 1295 | kfree(opts.release_agent); |
c6d57f33 | 1296 | kfree(opts.name); |
ddbcc7e8 | 1297 | mutex_unlock(&cgroup_mutex); |
bd89aabc | 1298 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
1299 | return ret; |
1300 | } | |
1301 | ||
b87221de | 1302 | static const struct super_operations cgroup_ops = { |
ddbcc7e8 PM |
1303 | .statfs = simple_statfs, |
1304 | .drop_inode = generic_delete_inode, | |
1305 | .show_options = cgroup_show_options, | |
1306 | .remount_fs = cgroup_remount, | |
1307 | }; | |
1308 | ||
cc31edce PM |
1309 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1310 | { | |
1311 | INIT_LIST_HEAD(&cgrp->sibling); | |
1312 | INIT_LIST_HEAD(&cgrp->children); | |
1313 | INIT_LIST_HEAD(&cgrp->css_sets); | |
1314 | INIT_LIST_HEAD(&cgrp->release_list); | |
72a8cb30 BB |
1315 | INIT_LIST_HEAD(&cgrp->pidlists); |
1316 | mutex_init(&cgrp->pidlist_mutex); | |
0dea1168 KS |
1317 | INIT_LIST_HEAD(&cgrp->event_list); |
1318 | spin_lock_init(&cgrp->event_list_lock); | |
cc31edce | 1319 | } |
c6d57f33 | 1320 | |
ddbcc7e8 PM |
1321 | static void init_cgroup_root(struct cgroupfs_root *root) |
1322 | { | |
bd89aabc | 1323 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
1324 | INIT_LIST_HEAD(&root->subsys_list); |
1325 | INIT_LIST_HEAD(&root->root_list); | |
1326 | root->number_of_cgroups = 1; | |
bd89aabc PM |
1327 | cgrp->root = root; |
1328 | cgrp->top_cgroup = cgrp; | |
cc31edce | 1329 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 PM |
1330 | } |
1331 | ||
2c6ab6d2 PM |
1332 | static bool init_root_id(struct cgroupfs_root *root) |
1333 | { | |
1334 | int ret = 0; | |
1335 | ||
1336 | do { | |
1337 | if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) | |
1338 | return false; | |
1339 | spin_lock(&hierarchy_id_lock); | |
1340 | /* Try to allocate the next unused ID */ | |
1341 | ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, | |
1342 | &root->hierarchy_id); | |
1343 | if (ret == -ENOSPC) | |
1344 | /* Try again starting from 0 */ | |
1345 | ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id); | |
1346 | if (!ret) { | |
1347 | next_hierarchy_id = root->hierarchy_id + 1; | |
1348 | } else if (ret != -EAGAIN) { | |
1349 | /* Can only get here if the 31-bit IDR is full ... */ | |
1350 | BUG_ON(ret); | |
1351 | } | |
1352 | spin_unlock(&hierarchy_id_lock); | |
1353 | } while (ret); | |
1354 | return true; | |
1355 | } | |
1356 | ||
ddbcc7e8 PM |
1357 | static int cgroup_test_super(struct super_block *sb, void *data) |
1358 | { | |
c6d57f33 | 1359 | struct cgroup_sb_opts *opts = data; |
ddbcc7e8 PM |
1360 | struct cgroupfs_root *root = sb->s_fs_info; |
1361 | ||
c6d57f33 PM |
1362 | /* If we asked for a name then it must match */ |
1363 | if (opts->name && strcmp(opts->name, root->name)) | |
1364 | return 0; | |
ddbcc7e8 | 1365 | |
2c6ab6d2 PM |
1366 | /* |
1367 | * If we asked for subsystems (or explicitly for no | |
1368 | * subsystems) then they must match | |
1369 | */ | |
1370 | if ((opts->subsys_bits || opts->none) | |
1371 | && (opts->subsys_bits != root->subsys_bits)) | |
ddbcc7e8 PM |
1372 | return 0; |
1373 | ||
1374 | return 1; | |
1375 | } | |
1376 | ||
c6d57f33 PM |
1377 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1378 | { | |
1379 | struct cgroupfs_root *root; | |
1380 | ||
2c6ab6d2 | 1381 | if (!opts->subsys_bits && !opts->none) |
c6d57f33 PM |
1382 | return NULL; |
1383 | ||
1384 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1385 | if (!root) | |
1386 | return ERR_PTR(-ENOMEM); | |
1387 | ||
2c6ab6d2 PM |
1388 | if (!init_root_id(root)) { |
1389 | kfree(root); | |
1390 | return ERR_PTR(-ENOMEM); | |
1391 | } | |
c6d57f33 | 1392 | init_cgroup_root(root); |
2c6ab6d2 | 1393 | |
c6d57f33 PM |
1394 | root->subsys_bits = opts->subsys_bits; |
1395 | root->flags = opts->flags; | |
1396 | if (opts->release_agent) | |
1397 | strcpy(root->release_agent_path, opts->release_agent); | |
1398 | if (opts->name) | |
1399 | strcpy(root->name, opts->name); | |
97978e6d DL |
1400 | if (opts->clone_children) |
1401 | set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags); | |
c6d57f33 PM |
1402 | return root; |
1403 | } | |
1404 | ||
2c6ab6d2 PM |
1405 | static void cgroup_drop_root(struct cgroupfs_root *root) |
1406 | { | |
1407 | if (!root) | |
1408 | return; | |
1409 | ||
1410 | BUG_ON(!root->hierarchy_id); | |
1411 | spin_lock(&hierarchy_id_lock); | |
1412 | ida_remove(&hierarchy_ida, root->hierarchy_id); | |
1413 | spin_unlock(&hierarchy_id_lock); | |
1414 | kfree(root); | |
1415 | } | |
1416 | ||
ddbcc7e8 PM |
1417 | static int cgroup_set_super(struct super_block *sb, void *data) |
1418 | { | |
1419 | int ret; | |
c6d57f33 PM |
1420 | struct cgroup_sb_opts *opts = data; |
1421 | ||
1422 | /* If we don't have a new root, we can't set up a new sb */ | |
1423 | if (!opts->new_root) | |
1424 | return -EINVAL; | |
1425 | ||
2c6ab6d2 | 1426 | BUG_ON(!opts->subsys_bits && !opts->none); |
ddbcc7e8 PM |
1427 | |
1428 | ret = set_anon_super(sb, NULL); | |
1429 | if (ret) | |
1430 | return ret; | |
1431 | ||
c6d57f33 PM |
1432 | sb->s_fs_info = opts->new_root; |
1433 | opts->new_root->sb = sb; | |
ddbcc7e8 PM |
1434 | |
1435 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
1436 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
1437 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
1438 | sb->s_op = &cgroup_ops; | |
1439 | ||
1440 | return 0; | |
1441 | } | |
1442 | ||
1443 | static int cgroup_get_rootdir(struct super_block *sb) | |
1444 | { | |
0df6a63f AV |
1445 | static const struct dentry_operations cgroup_dops = { |
1446 | .d_iput = cgroup_diput, | |
c72a04e3 | 1447 | .d_delete = cgroup_delete, |
0df6a63f AV |
1448 | }; |
1449 | ||
ddbcc7e8 PM |
1450 | struct inode *inode = |
1451 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
1452 | struct dentry *dentry; | |
1453 | ||
1454 | if (!inode) | |
1455 | return -ENOMEM; | |
1456 | ||
ddbcc7e8 PM |
1457 | inode->i_fop = &simple_dir_operations; |
1458 | inode->i_op = &cgroup_dir_inode_operations; | |
1459 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1460 | inc_nlink(inode); | |
1461 | dentry = d_alloc_root(inode); | |
1462 | if (!dentry) { | |
1463 | iput(inode); | |
1464 | return -ENOMEM; | |
1465 | } | |
1466 | sb->s_root = dentry; | |
0df6a63f AV |
1467 | /* for everything else we want ->d_op set */ |
1468 | sb->s_d_op = &cgroup_dops; | |
ddbcc7e8 PM |
1469 | return 0; |
1470 | } | |
1471 | ||
f7e83571 | 1472 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1473 | int flags, const char *unused_dev_name, |
f7e83571 | 1474 | void *data) |
ddbcc7e8 PM |
1475 | { |
1476 | struct cgroup_sb_opts opts; | |
c6d57f33 | 1477 | struct cgroupfs_root *root; |
ddbcc7e8 PM |
1478 | int ret = 0; |
1479 | struct super_block *sb; | |
c6d57f33 | 1480 | struct cgroupfs_root *new_root; |
ddbcc7e8 PM |
1481 | |
1482 | /* First find the desired set of subsystems */ | |
aae8aab4 | 1483 | mutex_lock(&cgroup_mutex); |
ddbcc7e8 | 1484 | ret = parse_cgroupfs_options(data, &opts); |
aae8aab4 | 1485 | mutex_unlock(&cgroup_mutex); |
c6d57f33 PM |
1486 | if (ret) |
1487 | goto out_err; | |
ddbcc7e8 | 1488 | |
c6d57f33 PM |
1489 | /* |
1490 | * Allocate a new cgroup root. We may not need it if we're | |
1491 | * reusing an existing hierarchy. | |
1492 | */ | |
1493 | new_root = cgroup_root_from_opts(&opts); | |
1494 | if (IS_ERR(new_root)) { | |
1495 | ret = PTR_ERR(new_root); | |
cf5d5941 | 1496 | goto drop_modules; |
81a6a5cd | 1497 | } |
c6d57f33 | 1498 | opts.new_root = new_root; |
ddbcc7e8 | 1499 | |
c6d57f33 PM |
1500 | /* Locate an existing or new sb for this hierarchy */ |
1501 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts); | |
ddbcc7e8 | 1502 | if (IS_ERR(sb)) { |
c6d57f33 | 1503 | ret = PTR_ERR(sb); |
2c6ab6d2 | 1504 | cgroup_drop_root(opts.new_root); |
cf5d5941 | 1505 | goto drop_modules; |
ddbcc7e8 PM |
1506 | } |
1507 | ||
c6d57f33 PM |
1508 | root = sb->s_fs_info; |
1509 | BUG_ON(!root); | |
1510 | if (root == opts.new_root) { | |
1511 | /* We used the new root structure, so this is a new hierarchy */ | |
1512 | struct list_head tmp_cg_links; | |
c12f65d4 | 1513 | struct cgroup *root_cgrp = &root->top_cgroup; |
817929ec | 1514 | struct inode *inode; |
c6d57f33 | 1515 | struct cgroupfs_root *existing_root; |
28fd5dfc | 1516 | int i; |
ddbcc7e8 PM |
1517 | |
1518 | BUG_ON(sb->s_root != NULL); | |
1519 | ||
1520 | ret = cgroup_get_rootdir(sb); | |
1521 | if (ret) | |
1522 | goto drop_new_super; | |
817929ec | 1523 | inode = sb->s_root->d_inode; |
ddbcc7e8 | 1524 | |
817929ec | 1525 | mutex_lock(&inode->i_mutex); |
ddbcc7e8 PM |
1526 | mutex_lock(&cgroup_mutex); |
1527 | ||
c6d57f33 PM |
1528 | if (strlen(root->name)) { |
1529 | /* Check for name clashes with existing mounts */ | |
1530 | for_each_active_root(existing_root) { | |
1531 | if (!strcmp(existing_root->name, root->name)) { | |
1532 | ret = -EBUSY; | |
1533 | mutex_unlock(&cgroup_mutex); | |
1534 | mutex_unlock(&inode->i_mutex); | |
1535 | goto drop_new_super; | |
1536 | } | |
1537 | } | |
1538 | } | |
1539 | ||
817929ec PM |
1540 | /* |
1541 | * We're accessing css_set_count without locking | |
1542 | * css_set_lock here, but that's OK - it can only be | |
1543 | * increased by someone holding cgroup_lock, and | |
1544 | * that's us. The worst that can happen is that we | |
1545 | * have some link structures left over | |
1546 | */ | |
1547 | ret = allocate_cg_links(css_set_count, &tmp_cg_links); | |
1548 | if (ret) { | |
1549 | mutex_unlock(&cgroup_mutex); | |
1550 | mutex_unlock(&inode->i_mutex); | |
1551 | goto drop_new_super; | |
1552 | } | |
1553 | ||
ddbcc7e8 PM |
1554 | ret = rebind_subsystems(root, root->subsys_bits); |
1555 | if (ret == -EBUSY) { | |
1556 | mutex_unlock(&cgroup_mutex); | |
817929ec | 1557 | mutex_unlock(&inode->i_mutex); |
c6d57f33 PM |
1558 | free_cg_links(&tmp_cg_links); |
1559 | goto drop_new_super; | |
ddbcc7e8 | 1560 | } |
cf5d5941 BB |
1561 | /* |
1562 | * There must be no failure case after here, since rebinding | |
1563 | * takes care of subsystems' refcounts, which are explicitly | |
1564 | * dropped in the failure exit path. | |
1565 | */ | |
ddbcc7e8 PM |
1566 | |
1567 | /* EBUSY should be the only error here */ | |
1568 | BUG_ON(ret); | |
1569 | ||
1570 | list_add(&root->root_list, &roots); | |
817929ec | 1571 | root_count++; |
ddbcc7e8 | 1572 | |
c12f65d4 | 1573 | sb->s_root->d_fsdata = root_cgrp; |
ddbcc7e8 PM |
1574 | root->top_cgroup.dentry = sb->s_root; |
1575 | ||
817929ec PM |
1576 | /* Link the top cgroup in this hierarchy into all |
1577 | * the css_set objects */ | |
1578 | write_lock(&css_set_lock); | |
28fd5dfc LZ |
1579 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { |
1580 | struct hlist_head *hhead = &css_set_table[i]; | |
1581 | struct hlist_node *node; | |
817929ec | 1582 | struct css_set *cg; |
28fd5dfc | 1583 | |
c12f65d4 LZ |
1584 | hlist_for_each_entry(cg, node, hhead, hlist) |
1585 | link_css_set(&tmp_cg_links, cg, root_cgrp); | |
28fd5dfc | 1586 | } |
817929ec PM |
1587 | write_unlock(&css_set_lock); |
1588 | ||
1589 | free_cg_links(&tmp_cg_links); | |
1590 | ||
c12f65d4 LZ |
1591 | BUG_ON(!list_empty(&root_cgrp->sibling)); |
1592 | BUG_ON(!list_empty(&root_cgrp->children)); | |
ddbcc7e8 PM |
1593 | BUG_ON(root->number_of_cgroups != 1); |
1594 | ||
c12f65d4 | 1595 | cgroup_populate_dir(root_cgrp); |
ddbcc7e8 | 1596 | mutex_unlock(&cgroup_mutex); |
34f77a90 | 1597 | mutex_unlock(&inode->i_mutex); |
c6d57f33 PM |
1598 | } else { |
1599 | /* | |
1600 | * We re-used an existing hierarchy - the new root (if | |
1601 | * any) is not needed | |
1602 | */ | |
2c6ab6d2 | 1603 | cgroup_drop_root(opts.new_root); |
cf5d5941 BB |
1604 | /* no subsys rebinding, so refcounts don't change */ |
1605 | drop_parsed_module_refcounts(opts.subsys_bits); | |
ddbcc7e8 PM |
1606 | } |
1607 | ||
c6d57f33 PM |
1608 | kfree(opts.release_agent); |
1609 | kfree(opts.name); | |
f7e83571 | 1610 | return dget(sb->s_root); |
ddbcc7e8 PM |
1611 | |
1612 | drop_new_super: | |
6f5bbff9 | 1613 | deactivate_locked_super(sb); |
cf5d5941 BB |
1614 | drop_modules: |
1615 | drop_parsed_module_refcounts(opts.subsys_bits); | |
c6d57f33 PM |
1616 | out_err: |
1617 | kfree(opts.release_agent); | |
1618 | kfree(opts.name); | |
f7e83571 | 1619 | return ERR_PTR(ret); |
ddbcc7e8 PM |
1620 | } |
1621 | ||
1622 | static void cgroup_kill_sb(struct super_block *sb) { | |
1623 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1624 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1625 | int ret; |
71cbb949 KM |
1626 | struct cg_cgroup_link *link; |
1627 | struct cg_cgroup_link *saved_link; | |
ddbcc7e8 PM |
1628 | |
1629 | BUG_ON(!root); | |
1630 | ||
1631 | BUG_ON(root->number_of_cgroups != 1); | |
bd89aabc PM |
1632 | BUG_ON(!list_empty(&cgrp->children)); |
1633 | BUG_ON(!list_empty(&cgrp->sibling)); | |
ddbcc7e8 PM |
1634 | |
1635 | mutex_lock(&cgroup_mutex); | |
1636 | ||
1637 | /* Rebind all subsystems back to the default hierarchy */ | |
1638 | ret = rebind_subsystems(root, 0); | |
1639 | /* Shouldn't be able to fail ... */ | |
1640 | BUG_ON(ret); | |
1641 | ||
817929ec PM |
1642 | /* |
1643 | * Release all the links from css_sets to this hierarchy's | |
1644 | * root cgroup | |
1645 | */ | |
1646 | write_lock(&css_set_lock); | |
71cbb949 KM |
1647 | |
1648 | list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, | |
1649 | cgrp_link_list) { | |
817929ec | 1650 | list_del(&link->cg_link_list); |
bd89aabc | 1651 | list_del(&link->cgrp_link_list); |
817929ec PM |
1652 | kfree(link); |
1653 | } | |
1654 | write_unlock(&css_set_lock); | |
1655 | ||
839ec545 PM |
1656 | if (!list_empty(&root->root_list)) { |
1657 | list_del(&root->root_list); | |
1658 | root_count--; | |
1659 | } | |
e5f6a860 | 1660 | |
ddbcc7e8 PM |
1661 | mutex_unlock(&cgroup_mutex); |
1662 | ||
ddbcc7e8 | 1663 | kill_litter_super(sb); |
2c6ab6d2 | 1664 | cgroup_drop_root(root); |
ddbcc7e8 PM |
1665 | } |
1666 | ||
1667 | static struct file_system_type cgroup_fs_type = { | |
1668 | .name = "cgroup", | |
f7e83571 | 1669 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1670 | .kill_sb = cgroup_kill_sb, |
1671 | }; | |
1672 | ||
676db4af GK |
1673 | static struct kobject *cgroup_kobj; |
1674 | ||
bd89aabc | 1675 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
ddbcc7e8 PM |
1676 | { |
1677 | return dentry->d_fsdata; | |
1678 | } | |
1679 | ||
1680 | static inline struct cftype *__d_cft(struct dentry *dentry) | |
1681 | { | |
1682 | return dentry->d_fsdata; | |
1683 | } | |
1684 | ||
a043e3b2 LZ |
1685 | /** |
1686 | * cgroup_path - generate the path of a cgroup | |
1687 | * @cgrp: the cgroup in question | |
1688 | * @buf: the buffer to write the path into | |
1689 | * @buflen: the length of the buffer | |
1690 | * | |
a47295e6 PM |
1691 | * Called with cgroup_mutex held or else with an RCU-protected cgroup |
1692 | * reference. Writes path of cgroup into buf. Returns 0 on success, | |
1693 | * -errno on error. | |
ddbcc7e8 | 1694 | */ |
bd89aabc | 1695 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
ddbcc7e8 PM |
1696 | { |
1697 | char *start; | |
9a9686b6 LZ |
1698 | struct dentry *dentry = rcu_dereference_check(cgrp->dentry, |
1699 | rcu_read_lock_held() || | |
1700 | cgroup_lock_is_held()); | |
ddbcc7e8 | 1701 | |
a47295e6 | 1702 | if (!dentry || cgrp == dummytop) { |
ddbcc7e8 PM |
1703 | /* |
1704 | * Inactive subsystems have no dentry for their root | |
1705 | * cgroup | |
1706 | */ | |
1707 | strcpy(buf, "/"); | |
1708 | return 0; | |
1709 | } | |
1710 | ||
1711 | start = buf + buflen; | |
1712 | ||
1713 | *--start = '\0'; | |
1714 | for (;;) { | |
a47295e6 | 1715 | int len = dentry->d_name.len; |
9a9686b6 | 1716 | |
ddbcc7e8 PM |
1717 | if ((start -= len) < buf) |
1718 | return -ENAMETOOLONG; | |
9a9686b6 | 1719 | memcpy(start, dentry->d_name.name, len); |
bd89aabc PM |
1720 | cgrp = cgrp->parent; |
1721 | if (!cgrp) | |
ddbcc7e8 | 1722 | break; |
9a9686b6 LZ |
1723 | |
1724 | dentry = rcu_dereference_check(cgrp->dentry, | |
1725 | rcu_read_lock_held() || | |
1726 | cgroup_lock_is_held()); | |
bd89aabc | 1727 | if (!cgrp->parent) |
ddbcc7e8 PM |
1728 | continue; |
1729 | if (--start < buf) | |
1730 | return -ENAMETOOLONG; | |
1731 | *start = '/'; | |
1732 | } | |
1733 | memmove(buf, start, buf + buflen - start); | |
1734 | return 0; | |
1735 | } | |
67523c48 | 1736 | EXPORT_SYMBOL_GPL(cgroup_path); |
ddbcc7e8 | 1737 | |
a043e3b2 LZ |
1738 | /** |
1739 | * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' | |
1740 | * @cgrp: the cgroup the task is attaching to | |
1741 | * @tsk: the task to be attached | |
bbcb81d0 | 1742 | * |
a043e3b2 LZ |
1743 | * Call holding cgroup_mutex. May take task_lock of |
1744 | * the task 'tsk' during call. | |
bbcb81d0 | 1745 | */ |
956db3ca | 1746 | int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
bbcb81d0 PM |
1747 | { |
1748 | int retval = 0; | |
2468c723 | 1749 | struct cgroup_subsys *ss, *failed_ss = NULL; |
bd89aabc | 1750 | struct cgroup *oldcgrp; |
77efecd9 | 1751 | struct css_set *cg; |
817929ec | 1752 | struct css_set *newcg; |
bd89aabc | 1753 | struct cgroupfs_root *root = cgrp->root; |
bbcb81d0 PM |
1754 | |
1755 | /* Nothing to do if the task is already in that cgroup */ | |
7717f7ba | 1756 | oldcgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 1757 | if (cgrp == oldcgrp) |
bbcb81d0 PM |
1758 | return 0; |
1759 | ||
1760 | for_each_subsys(root, ss) { | |
1761 | if (ss->can_attach) { | |
be367d09 | 1762 | retval = ss->can_attach(ss, cgrp, tsk, false); |
2468c723 DN |
1763 | if (retval) { |
1764 | /* | |
1765 | * Remember on which subsystem the can_attach() | |
1766 | * failed, so that we only call cancel_attach() | |
1767 | * against the subsystems whose can_attach() | |
1768 | * succeeded. (See below) | |
1769 | */ | |
1770 | failed_ss = ss; | |
1771 | goto out; | |
1772 | } | |
bbcb81d0 PM |
1773 | } |
1774 | } | |
1775 | ||
77efecd9 LJ |
1776 | task_lock(tsk); |
1777 | cg = tsk->cgroups; | |
1778 | get_css_set(cg); | |
1779 | task_unlock(tsk); | |
817929ec PM |
1780 | /* |
1781 | * Locate or allocate a new css_set for this task, | |
1782 | * based on its final set of cgroups | |
1783 | */ | |
bd89aabc | 1784 | newcg = find_css_set(cg, cgrp); |
77efecd9 | 1785 | put_css_set(cg); |
2468c723 DN |
1786 | if (!newcg) { |
1787 | retval = -ENOMEM; | |
1788 | goto out; | |
1789 | } | |
817929ec | 1790 | |
bbcb81d0 PM |
1791 | task_lock(tsk); |
1792 | if (tsk->flags & PF_EXITING) { | |
1793 | task_unlock(tsk); | |
817929ec | 1794 | put_css_set(newcg); |
2468c723 DN |
1795 | retval = -ESRCH; |
1796 | goto out; | |
bbcb81d0 | 1797 | } |
817929ec | 1798 | rcu_assign_pointer(tsk->cgroups, newcg); |
bbcb81d0 PM |
1799 | task_unlock(tsk); |
1800 | ||
817929ec PM |
1801 | /* Update the css_set linked lists if we're using them */ |
1802 | write_lock(&css_set_lock); | |
8d258797 PC |
1803 | if (!list_empty(&tsk->cg_list)) |
1804 | list_move(&tsk->cg_list, &newcg->tasks); | |
817929ec PM |
1805 | write_unlock(&css_set_lock); |
1806 | ||
bbcb81d0 | 1807 | for_each_subsys(root, ss) { |
e18f6318 | 1808 | if (ss->attach) |
be367d09 | 1809 | ss->attach(ss, cgrp, oldcgrp, tsk, false); |
bbcb81d0 | 1810 | } |
bd89aabc | 1811 | set_bit(CGRP_RELEASABLE, &oldcgrp->flags); |
bbcb81d0 | 1812 | synchronize_rcu(); |
817929ec | 1813 | put_css_set(cg); |
ec64f515 KH |
1814 | |
1815 | /* | |
1816 | * wake up rmdir() waiter. the rmdir should fail since the cgroup | |
1817 | * is no longer empty. | |
1818 | */ | |
88703267 | 1819 | cgroup_wakeup_rmdir_waiter(cgrp); |
2468c723 DN |
1820 | out: |
1821 | if (retval) { | |
1822 | for_each_subsys(root, ss) { | |
1823 | if (ss == failed_ss) | |
1824 | /* | |
1825 | * This subsystem was the one that failed the | |
1826 | * can_attach() check earlier, so we don't need | |
1827 | * to call cancel_attach() against it or any | |
1828 | * remaining subsystems. | |
1829 | */ | |
1830 | break; | |
1831 | if (ss->cancel_attach) | |
1832 | ss->cancel_attach(ss, cgrp, tsk, false); | |
1833 | } | |
1834 | } | |
1835 | return retval; | |
bbcb81d0 PM |
1836 | } |
1837 | ||
d7926ee3 | 1838 | /** |
31583bb0 MT |
1839 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' |
1840 | * @from: attach to all cgroups of a given task | |
d7926ee3 SS |
1841 | * @tsk: the task to be attached |
1842 | */ | |
31583bb0 | 1843 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) |
d7926ee3 SS |
1844 | { |
1845 | struct cgroupfs_root *root; | |
d7926ee3 SS |
1846 | int retval = 0; |
1847 | ||
1848 | cgroup_lock(); | |
1849 | for_each_active_root(root) { | |
31583bb0 MT |
1850 | struct cgroup *from_cg = task_cgroup_from_root(from, root); |
1851 | ||
1852 | retval = cgroup_attach_task(from_cg, tsk); | |
d7926ee3 SS |
1853 | if (retval) |
1854 | break; | |
1855 | } | |
1856 | cgroup_unlock(); | |
1857 | ||
1858 | return retval; | |
1859 | } | |
31583bb0 | 1860 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
d7926ee3 | 1861 | |
bbcb81d0 | 1862 | /* |
af351026 PM |
1863 | * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex |
1864 | * held. May take task_lock of task | |
bbcb81d0 | 1865 | */ |
af351026 | 1866 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid) |
bbcb81d0 | 1867 | { |
bbcb81d0 | 1868 | struct task_struct *tsk; |
c69e8d9c | 1869 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
1870 | int ret; |
1871 | ||
bbcb81d0 PM |
1872 | if (pid) { |
1873 | rcu_read_lock(); | |
73507f33 | 1874 | tsk = find_task_by_vpid(pid); |
bbcb81d0 PM |
1875 | if (!tsk || tsk->flags & PF_EXITING) { |
1876 | rcu_read_unlock(); | |
1877 | return -ESRCH; | |
1878 | } | |
bbcb81d0 | 1879 | |
c69e8d9c DH |
1880 | tcred = __task_cred(tsk); |
1881 | if (cred->euid && | |
1882 | cred->euid != tcred->uid && | |
1883 | cred->euid != tcred->suid) { | |
1884 | rcu_read_unlock(); | |
bbcb81d0 PM |
1885 | return -EACCES; |
1886 | } | |
c69e8d9c DH |
1887 | get_task_struct(tsk); |
1888 | rcu_read_unlock(); | |
bbcb81d0 PM |
1889 | } else { |
1890 | tsk = current; | |
1891 | get_task_struct(tsk); | |
1892 | } | |
1893 | ||
956db3ca | 1894 | ret = cgroup_attach_task(cgrp, tsk); |
bbcb81d0 PM |
1895 | put_task_struct(tsk); |
1896 | return ret; | |
1897 | } | |
1898 | ||
af351026 PM |
1899 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
1900 | { | |
1901 | int ret; | |
1902 | if (!cgroup_lock_live_group(cgrp)) | |
1903 | return -ENODEV; | |
1904 | ret = attach_task_by_pid(cgrp, pid); | |
1905 | cgroup_unlock(); | |
1906 | return ret; | |
1907 | } | |
1908 | ||
e788e066 PM |
1909 | /** |
1910 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
1911 | * @cgrp: the cgroup to be checked for liveness | |
1912 | * | |
84eea842 PM |
1913 | * On success, returns true; the lock should be later released with |
1914 | * cgroup_unlock(). On failure returns false with no lock held. | |
e788e066 | 1915 | */ |
84eea842 | 1916 | bool cgroup_lock_live_group(struct cgroup *cgrp) |
e788e066 PM |
1917 | { |
1918 | mutex_lock(&cgroup_mutex); | |
1919 | if (cgroup_is_removed(cgrp)) { | |
1920 | mutex_unlock(&cgroup_mutex); | |
1921 | return false; | |
1922 | } | |
1923 | return true; | |
1924 | } | |
67523c48 | 1925 | EXPORT_SYMBOL_GPL(cgroup_lock_live_group); |
e788e066 PM |
1926 | |
1927 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, | |
1928 | const char *buffer) | |
1929 | { | |
1930 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); | |
f4a2589f EK |
1931 | if (strlen(buffer) >= PATH_MAX) |
1932 | return -EINVAL; | |
e788e066 PM |
1933 | if (!cgroup_lock_live_group(cgrp)) |
1934 | return -ENODEV; | |
1935 | strcpy(cgrp->root->release_agent_path, buffer); | |
84eea842 | 1936 | cgroup_unlock(); |
e788e066 PM |
1937 | return 0; |
1938 | } | |
1939 | ||
1940 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, | |
1941 | struct seq_file *seq) | |
1942 | { | |
1943 | if (!cgroup_lock_live_group(cgrp)) | |
1944 | return -ENODEV; | |
1945 | seq_puts(seq, cgrp->root->release_agent_path); | |
1946 | seq_putc(seq, '\n'); | |
84eea842 | 1947 | cgroup_unlock(); |
e788e066 PM |
1948 | return 0; |
1949 | } | |
1950 | ||
84eea842 PM |
1951 | /* A buffer size big enough for numbers or short strings */ |
1952 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
1953 | ||
e73d2c61 | 1954 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
f4c753b7 PM |
1955 | struct file *file, |
1956 | const char __user *userbuf, | |
1957 | size_t nbytes, loff_t *unused_ppos) | |
355e0c48 | 1958 | { |
84eea842 | 1959 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
355e0c48 | 1960 | int retval = 0; |
355e0c48 PM |
1961 | char *end; |
1962 | ||
1963 | if (!nbytes) | |
1964 | return -EINVAL; | |
1965 | if (nbytes >= sizeof(buffer)) | |
1966 | return -E2BIG; | |
1967 | if (copy_from_user(buffer, userbuf, nbytes)) | |
1968 | return -EFAULT; | |
1969 | ||
1970 | buffer[nbytes] = 0; /* nul-terminate */ | |
e73d2c61 | 1971 | if (cft->write_u64) { |
478988d3 | 1972 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
e73d2c61 PM |
1973 | if (*end) |
1974 | return -EINVAL; | |
1975 | retval = cft->write_u64(cgrp, cft, val); | |
1976 | } else { | |
478988d3 | 1977 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
e73d2c61 PM |
1978 | if (*end) |
1979 | return -EINVAL; | |
1980 | retval = cft->write_s64(cgrp, cft, val); | |
1981 | } | |
355e0c48 PM |
1982 | if (!retval) |
1983 | retval = nbytes; | |
1984 | return retval; | |
1985 | } | |
1986 | ||
db3b1497 PM |
1987 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
1988 | struct file *file, | |
1989 | const char __user *userbuf, | |
1990 | size_t nbytes, loff_t *unused_ppos) | |
1991 | { | |
84eea842 | 1992 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
db3b1497 PM |
1993 | int retval = 0; |
1994 | size_t max_bytes = cft->max_write_len; | |
1995 | char *buffer = local_buffer; | |
1996 | ||
1997 | if (!max_bytes) | |
1998 | max_bytes = sizeof(local_buffer) - 1; | |
1999 | if (nbytes >= max_bytes) | |
2000 | return -E2BIG; | |
2001 | /* Allocate a dynamic buffer if we need one */ | |
2002 | if (nbytes >= sizeof(local_buffer)) { | |
2003 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
2004 | if (buffer == NULL) | |
2005 | return -ENOMEM; | |
2006 | } | |
5a3eb9f6 LZ |
2007 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
2008 | retval = -EFAULT; | |
2009 | goto out; | |
2010 | } | |
db3b1497 PM |
2011 | |
2012 | buffer[nbytes] = 0; /* nul-terminate */ | |
478988d3 | 2013 | retval = cft->write_string(cgrp, cft, strstrip(buffer)); |
db3b1497 PM |
2014 | if (!retval) |
2015 | retval = nbytes; | |
5a3eb9f6 | 2016 | out: |
db3b1497 PM |
2017 | if (buffer != local_buffer) |
2018 | kfree(buffer); | |
2019 | return retval; | |
2020 | } | |
2021 | ||
ddbcc7e8 PM |
2022 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
2023 | size_t nbytes, loff_t *ppos) | |
2024 | { | |
2025 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2026 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2027 | |
75139b82 | 2028 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 | 2029 | return -ENODEV; |
355e0c48 | 2030 | if (cft->write) |
bd89aabc | 2031 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
e73d2c61 PM |
2032 | if (cft->write_u64 || cft->write_s64) |
2033 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); | |
db3b1497 PM |
2034 | if (cft->write_string) |
2035 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); | |
d447ea2f PE |
2036 | if (cft->trigger) { |
2037 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); | |
2038 | return ret ? ret : nbytes; | |
2039 | } | |
355e0c48 | 2040 | return -EINVAL; |
ddbcc7e8 PM |
2041 | } |
2042 | ||
f4c753b7 PM |
2043 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
2044 | struct file *file, | |
2045 | char __user *buf, size_t nbytes, | |
2046 | loff_t *ppos) | |
ddbcc7e8 | 2047 | { |
84eea842 | 2048 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
f4c753b7 | 2049 | u64 val = cft->read_u64(cgrp, cft); |
ddbcc7e8 PM |
2050 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
2051 | ||
2052 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2053 | } | |
2054 | ||
e73d2c61 PM |
2055 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
2056 | struct file *file, | |
2057 | char __user *buf, size_t nbytes, | |
2058 | loff_t *ppos) | |
2059 | { | |
84eea842 | 2060 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
e73d2c61 PM |
2061 | s64 val = cft->read_s64(cgrp, cft); |
2062 | int len = sprintf(tmp, "%lld\n", (long long) val); | |
2063 | ||
2064 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2065 | } | |
2066 | ||
ddbcc7e8 PM |
2067 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
2068 | size_t nbytes, loff_t *ppos) | |
2069 | { | |
2070 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2071 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2072 | |
75139b82 | 2073 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 PM |
2074 | return -ENODEV; |
2075 | ||
2076 | if (cft->read) | |
bd89aabc | 2077 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
f4c753b7 PM |
2078 | if (cft->read_u64) |
2079 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); | |
e73d2c61 PM |
2080 | if (cft->read_s64) |
2081 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); | |
ddbcc7e8 PM |
2082 | return -EINVAL; |
2083 | } | |
2084 | ||
91796569 PM |
2085 | /* |
2086 | * seqfile ops/methods for returning structured data. Currently just | |
2087 | * supports string->u64 maps, but can be extended in future. | |
2088 | */ | |
2089 | ||
2090 | struct cgroup_seqfile_state { | |
2091 | struct cftype *cft; | |
2092 | struct cgroup *cgroup; | |
2093 | }; | |
2094 | ||
2095 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) | |
2096 | { | |
2097 | struct seq_file *sf = cb->state; | |
2098 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
2099 | } | |
2100 | ||
2101 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
2102 | { | |
2103 | struct cgroup_seqfile_state *state = m->private; | |
2104 | struct cftype *cft = state->cft; | |
29486df3 SH |
2105 | if (cft->read_map) { |
2106 | struct cgroup_map_cb cb = { | |
2107 | .fill = cgroup_map_add, | |
2108 | .state = m, | |
2109 | }; | |
2110 | return cft->read_map(state->cgroup, cft, &cb); | |
2111 | } | |
2112 | return cft->read_seq_string(state->cgroup, cft, m); | |
91796569 PM |
2113 | } |
2114 | ||
96930a63 | 2115 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
91796569 PM |
2116 | { |
2117 | struct seq_file *seq = file->private_data; | |
2118 | kfree(seq->private); | |
2119 | return single_release(inode, file); | |
2120 | } | |
2121 | ||
828c0950 | 2122 | static const struct file_operations cgroup_seqfile_operations = { |
91796569 | 2123 | .read = seq_read, |
e788e066 | 2124 | .write = cgroup_file_write, |
91796569 PM |
2125 | .llseek = seq_lseek, |
2126 | .release = cgroup_seqfile_release, | |
2127 | }; | |
2128 | ||
ddbcc7e8 PM |
2129 | static int cgroup_file_open(struct inode *inode, struct file *file) |
2130 | { | |
2131 | int err; | |
2132 | struct cftype *cft; | |
2133 | ||
2134 | err = generic_file_open(inode, file); | |
2135 | if (err) | |
2136 | return err; | |
ddbcc7e8 | 2137 | cft = __d_cft(file->f_dentry); |
75139b82 | 2138 | |
29486df3 | 2139 | if (cft->read_map || cft->read_seq_string) { |
91796569 PM |
2140 | struct cgroup_seqfile_state *state = |
2141 | kzalloc(sizeof(*state), GFP_USER); | |
2142 | if (!state) | |
2143 | return -ENOMEM; | |
2144 | state->cft = cft; | |
2145 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); | |
2146 | file->f_op = &cgroup_seqfile_operations; | |
2147 | err = single_open(file, cgroup_seqfile_show, state); | |
2148 | if (err < 0) | |
2149 | kfree(state); | |
2150 | } else if (cft->open) | |
ddbcc7e8 PM |
2151 | err = cft->open(inode, file); |
2152 | else | |
2153 | err = 0; | |
2154 | ||
2155 | return err; | |
2156 | } | |
2157 | ||
2158 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
2159 | { | |
2160 | struct cftype *cft = __d_cft(file->f_dentry); | |
2161 | if (cft->release) | |
2162 | return cft->release(inode, file); | |
2163 | return 0; | |
2164 | } | |
2165 | ||
2166 | /* | |
2167 | * cgroup_rename - Only allow simple rename of directories in place. | |
2168 | */ | |
2169 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2170 | struct inode *new_dir, struct dentry *new_dentry) | |
2171 | { | |
2172 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) | |
2173 | return -ENOTDIR; | |
2174 | if (new_dentry->d_inode) | |
2175 | return -EEXIST; | |
2176 | if (old_dir != new_dir) | |
2177 | return -EIO; | |
2178 | return simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2179 | } | |
2180 | ||
828c0950 | 2181 | static const struct file_operations cgroup_file_operations = { |
ddbcc7e8 PM |
2182 | .read = cgroup_file_read, |
2183 | .write = cgroup_file_write, | |
2184 | .llseek = generic_file_llseek, | |
2185 | .open = cgroup_file_open, | |
2186 | .release = cgroup_file_release, | |
2187 | }; | |
2188 | ||
6e1d5dcc | 2189 | static const struct inode_operations cgroup_dir_inode_operations = { |
c72a04e3 | 2190 | .lookup = cgroup_lookup, |
ddbcc7e8 PM |
2191 | .mkdir = cgroup_mkdir, |
2192 | .rmdir = cgroup_rmdir, | |
2193 | .rename = cgroup_rename, | |
2194 | }; | |
2195 | ||
c72a04e3 AV |
2196 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) |
2197 | { | |
2198 | if (dentry->d_name.len > NAME_MAX) | |
2199 | return ERR_PTR(-ENAMETOOLONG); | |
2200 | d_add(dentry, NULL); | |
2201 | return NULL; | |
2202 | } | |
2203 | ||
0dea1168 KS |
2204 | /* |
2205 | * Check if a file is a control file | |
2206 | */ | |
2207 | static inline struct cftype *__file_cft(struct file *file) | |
2208 | { | |
2209 | if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations) | |
2210 | return ERR_PTR(-EINVAL); | |
2211 | return __d_cft(file->f_dentry); | |
2212 | } | |
2213 | ||
5adcee1d NP |
2214 | static int cgroup_create_file(struct dentry *dentry, mode_t mode, |
2215 | struct super_block *sb) | |
2216 | { | |
ddbcc7e8 PM |
2217 | struct inode *inode; |
2218 | ||
2219 | if (!dentry) | |
2220 | return -ENOENT; | |
2221 | if (dentry->d_inode) | |
2222 | return -EEXIST; | |
2223 | ||
2224 | inode = cgroup_new_inode(mode, sb); | |
2225 | if (!inode) | |
2226 | return -ENOMEM; | |
2227 | ||
2228 | if (S_ISDIR(mode)) { | |
2229 | inode->i_op = &cgroup_dir_inode_operations; | |
2230 | inode->i_fop = &simple_dir_operations; | |
2231 | ||
2232 | /* start off with i_nlink == 2 (for "." entry) */ | |
2233 | inc_nlink(inode); | |
2234 | ||
2235 | /* start with the directory inode held, so that we can | |
2236 | * populate it without racing with another mkdir */ | |
817929ec | 2237 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
ddbcc7e8 PM |
2238 | } else if (S_ISREG(mode)) { |
2239 | inode->i_size = 0; | |
2240 | inode->i_fop = &cgroup_file_operations; | |
2241 | } | |
ddbcc7e8 PM |
2242 | d_instantiate(dentry, inode); |
2243 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2244 | return 0; | |
2245 | } | |
2246 | ||
2247 | /* | |
a043e3b2 LZ |
2248 | * cgroup_create_dir - create a directory for an object. |
2249 | * @cgrp: the cgroup we create the directory for. It must have a valid | |
2250 | * ->parent field. And we are going to fill its ->dentry field. | |
2251 | * @dentry: dentry of the new cgroup | |
2252 | * @mode: mode to set on new directory. | |
ddbcc7e8 | 2253 | */ |
bd89aabc | 2254 | static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry, |
099fca32 | 2255 | mode_t mode) |
ddbcc7e8 PM |
2256 | { |
2257 | struct dentry *parent; | |
2258 | int error = 0; | |
2259 | ||
bd89aabc PM |
2260 | parent = cgrp->parent->dentry; |
2261 | error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb); | |
ddbcc7e8 | 2262 | if (!error) { |
bd89aabc | 2263 | dentry->d_fsdata = cgrp; |
ddbcc7e8 | 2264 | inc_nlink(parent->d_inode); |
a47295e6 | 2265 | rcu_assign_pointer(cgrp->dentry, dentry); |
ddbcc7e8 PM |
2266 | dget(dentry); |
2267 | } | |
2268 | dput(dentry); | |
2269 | ||
2270 | return error; | |
2271 | } | |
2272 | ||
099fca32 LZ |
2273 | /** |
2274 | * cgroup_file_mode - deduce file mode of a control file | |
2275 | * @cft: the control file in question | |
2276 | * | |
2277 | * returns cft->mode if ->mode is not 0 | |
2278 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
2279 | * returns S_IRUGO if it has only a read handler | |
2280 | * returns S_IWUSR if it has only a write hander | |
2281 | */ | |
2282 | static mode_t cgroup_file_mode(const struct cftype *cft) | |
2283 | { | |
2284 | mode_t mode = 0; | |
2285 | ||
2286 | if (cft->mode) | |
2287 | return cft->mode; | |
2288 | ||
2289 | if (cft->read || cft->read_u64 || cft->read_s64 || | |
2290 | cft->read_map || cft->read_seq_string) | |
2291 | mode |= S_IRUGO; | |
2292 | ||
2293 | if (cft->write || cft->write_u64 || cft->write_s64 || | |
2294 | cft->write_string || cft->trigger) | |
2295 | mode |= S_IWUSR; | |
2296 | ||
2297 | return mode; | |
2298 | } | |
2299 | ||
bd89aabc | 2300 | int cgroup_add_file(struct cgroup *cgrp, |
ddbcc7e8 PM |
2301 | struct cgroup_subsys *subsys, |
2302 | const struct cftype *cft) | |
2303 | { | |
bd89aabc | 2304 | struct dentry *dir = cgrp->dentry; |
ddbcc7e8 PM |
2305 | struct dentry *dentry; |
2306 | int error; | |
099fca32 | 2307 | mode_t mode; |
ddbcc7e8 PM |
2308 | |
2309 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; | |
bd89aabc | 2310 | if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { |
ddbcc7e8 PM |
2311 | strcpy(name, subsys->name); |
2312 | strcat(name, "."); | |
2313 | } | |
2314 | strcat(name, cft->name); | |
2315 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); | |
2316 | dentry = lookup_one_len(name, dir, strlen(name)); | |
2317 | if (!IS_ERR(dentry)) { | |
099fca32 LZ |
2318 | mode = cgroup_file_mode(cft); |
2319 | error = cgroup_create_file(dentry, mode | S_IFREG, | |
bd89aabc | 2320 | cgrp->root->sb); |
ddbcc7e8 PM |
2321 | if (!error) |
2322 | dentry->d_fsdata = (void *)cft; | |
2323 | dput(dentry); | |
2324 | } else | |
2325 | error = PTR_ERR(dentry); | |
2326 | return error; | |
2327 | } | |
e6a1105b | 2328 | EXPORT_SYMBOL_GPL(cgroup_add_file); |
ddbcc7e8 | 2329 | |
bd89aabc | 2330 | int cgroup_add_files(struct cgroup *cgrp, |
ddbcc7e8 PM |
2331 | struct cgroup_subsys *subsys, |
2332 | const struct cftype cft[], | |
2333 | int count) | |
2334 | { | |
2335 | int i, err; | |
2336 | for (i = 0; i < count; i++) { | |
bd89aabc | 2337 | err = cgroup_add_file(cgrp, subsys, &cft[i]); |
ddbcc7e8 PM |
2338 | if (err) |
2339 | return err; | |
2340 | } | |
2341 | return 0; | |
2342 | } | |
e6a1105b | 2343 | EXPORT_SYMBOL_GPL(cgroup_add_files); |
ddbcc7e8 | 2344 | |
a043e3b2 LZ |
2345 | /** |
2346 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2347 | * @cgrp: the cgroup in question | |
2348 | * | |
2349 | * Return the number of tasks in the cgroup. | |
2350 | */ | |
bd89aabc | 2351 | int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2352 | { |
2353 | int count = 0; | |
71cbb949 | 2354 | struct cg_cgroup_link *link; |
817929ec PM |
2355 | |
2356 | read_lock(&css_set_lock); | |
71cbb949 | 2357 | list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { |
146aa1bd | 2358 | count += atomic_read(&link->cg->refcount); |
817929ec PM |
2359 | } |
2360 | read_unlock(&css_set_lock); | |
bbcb81d0 PM |
2361 | return count; |
2362 | } | |
2363 | ||
817929ec PM |
2364 | /* |
2365 | * Advance a list_head iterator. The iterator should be positioned at | |
2366 | * the start of a css_set | |
2367 | */ | |
bd89aabc | 2368 | static void cgroup_advance_iter(struct cgroup *cgrp, |
7717f7ba | 2369 | struct cgroup_iter *it) |
817929ec PM |
2370 | { |
2371 | struct list_head *l = it->cg_link; | |
2372 | struct cg_cgroup_link *link; | |
2373 | struct css_set *cg; | |
2374 | ||
2375 | /* Advance to the next non-empty css_set */ | |
2376 | do { | |
2377 | l = l->next; | |
bd89aabc | 2378 | if (l == &cgrp->css_sets) { |
817929ec PM |
2379 | it->cg_link = NULL; |
2380 | return; | |
2381 | } | |
bd89aabc | 2382 | link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); |
817929ec PM |
2383 | cg = link->cg; |
2384 | } while (list_empty(&cg->tasks)); | |
2385 | it->cg_link = l; | |
2386 | it->task = cg->tasks.next; | |
2387 | } | |
2388 | ||
31a7df01 CW |
2389 | /* |
2390 | * To reduce the fork() overhead for systems that are not actually | |
2391 | * using their cgroups capability, we don't maintain the lists running | |
2392 | * through each css_set to its tasks until we see the list actually | |
2393 | * used - in other words after the first call to cgroup_iter_start(). | |
2394 | * | |
2395 | * The tasklist_lock is not held here, as do_each_thread() and | |
2396 | * while_each_thread() are protected by RCU. | |
2397 | */ | |
3df91fe3 | 2398 | static void cgroup_enable_task_cg_lists(void) |
31a7df01 CW |
2399 | { |
2400 | struct task_struct *p, *g; | |
2401 | write_lock(&css_set_lock); | |
2402 | use_task_css_set_links = 1; | |
2403 | do_each_thread(g, p) { | |
2404 | task_lock(p); | |
0e04388f LZ |
2405 | /* |
2406 | * We should check if the process is exiting, otherwise | |
2407 | * it will race with cgroup_exit() in that the list | |
2408 | * entry won't be deleted though the process has exited. | |
2409 | */ | |
2410 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
31a7df01 CW |
2411 | list_add(&p->cg_list, &p->cgroups->tasks); |
2412 | task_unlock(p); | |
2413 | } while_each_thread(g, p); | |
2414 | write_unlock(&css_set_lock); | |
2415 | } | |
2416 | ||
bd89aabc | 2417 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
817929ec PM |
2418 | { |
2419 | /* | |
2420 | * The first time anyone tries to iterate across a cgroup, | |
2421 | * we need to enable the list linking each css_set to its | |
2422 | * tasks, and fix up all existing tasks. | |
2423 | */ | |
31a7df01 CW |
2424 | if (!use_task_css_set_links) |
2425 | cgroup_enable_task_cg_lists(); | |
2426 | ||
817929ec | 2427 | read_lock(&css_set_lock); |
bd89aabc PM |
2428 | it->cg_link = &cgrp->css_sets; |
2429 | cgroup_advance_iter(cgrp, it); | |
817929ec PM |
2430 | } |
2431 | ||
bd89aabc | 2432 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
817929ec PM |
2433 | struct cgroup_iter *it) |
2434 | { | |
2435 | struct task_struct *res; | |
2436 | struct list_head *l = it->task; | |
2019f634 | 2437 | struct cg_cgroup_link *link; |
817929ec PM |
2438 | |
2439 | /* If the iterator cg is NULL, we have no tasks */ | |
2440 | if (!it->cg_link) | |
2441 | return NULL; | |
2442 | res = list_entry(l, struct task_struct, cg_list); | |
2443 | /* Advance iterator to find next entry */ | |
2444 | l = l->next; | |
2019f634 LJ |
2445 | link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); |
2446 | if (l == &link->cg->tasks) { | |
817929ec PM |
2447 | /* We reached the end of this task list - move on to |
2448 | * the next cg_cgroup_link */ | |
bd89aabc | 2449 | cgroup_advance_iter(cgrp, it); |
817929ec PM |
2450 | } else { |
2451 | it->task = l; | |
2452 | } | |
2453 | return res; | |
2454 | } | |
2455 | ||
bd89aabc | 2456 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
817929ec PM |
2457 | { |
2458 | read_unlock(&css_set_lock); | |
2459 | } | |
2460 | ||
31a7df01 CW |
2461 | static inline int started_after_time(struct task_struct *t1, |
2462 | struct timespec *time, | |
2463 | struct task_struct *t2) | |
2464 | { | |
2465 | int start_diff = timespec_compare(&t1->start_time, time); | |
2466 | if (start_diff > 0) { | |
2467 | return 1; | |
2468 | } else if (start_diff < 0) { | |
2469 | return 0; | |
2470 | } else { | |
2471 | /* | |
2472 | * Arbitrarily, if two processes started at the same | |
2473 | * time, we'll say that the lower pointer value | |
2474 | * started first. Note that t2 may have exited by now | |
2475 | * so this may not be a valid pointer any longer, but | |
2476 | * that's fine - it still serves to distinguish | |
2477 | * between two tasks started (effectively) simultaneously. | |
2478 | */ | |
2479 | return t1 > t2; | |
2480 | } | |
2481 | } | |
2482 | ||
2483 | /* | |
2484 | * This function is a callback from heap_insert() and is used to order | |
2485 | * the heap. | |
2486 | * In this case we order the heap in descending task start time. | |
2487 | */ | |
2488 | static inline int started_after(void *p1, void *p2) | |
2489 | { | |
2490 | struct task_struct *t1 = p1; | |
2491 | struct task_struct *t2 = p2; | |
2492 | return started_after_time(t1, &t2->start_time, t2); | |
2493 | } | |
2494 | ||
2495 | /** | |
2496 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
2497 | * @scan: struct cgroup_scanner containing arguments for the scan | |
2498 | * | |
2499 | * Arguments include pointers to callback functions test_task() and | |
2500 | * process_task(). | |
2501 | * Iterate through all the tasks in a cgroup, calling test_task() for each, | |
2502 | * and if it returns true, call process_task() for it also. | |
2503 | * The test_task pointer may be NULL, meaning always true (select all tasks). | |
2504 | * Effectively duplicates cgroup_iter_{start,next,end}() | |
2505 | * but does not lock css_set_lock for the call to process_task(). | |
2506 | * The struct cgroup_scanner may be embedded in any structure of the caller's | |
2507 | * creation. | |
2508 | * It is guaranteed that process_task() will act on every task that | |
2509 | * is a member of the cgroup for the duration of this call. This | |
2510 | * function may or may not call process_task() for tasks that exit | |
2511 | * or move to a different cgroup during the call, or are forked or | |
2512 | * move into the cgroup during the call. | |
2513 | * | |
2514 | * Note that test_task() may be called with locks held, and may in some | |
2515 | * situations be called multiple times for the same task, so it should | |
2516 | * be cheap. | |
2517 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been | |
2518 | * pre-allocated and will be used for heap operations (and its "gt" member will | |
2519 | * be overwritten), else a temporary heap will be used (allocation of which | |
2520 | * may cause this function to fail). | |
2521 | */ | |
2522 | int cgroup_scan_tasks(struct cgroup_scanner *scan) | |
2523 | { | |
2524 | int retval, i; | |
2525 | struct cgroup_iter it; | |
2526 | struct task_struct *p, *dropped; | |
2527 | /* Never dereference latest_task, since it's not refcounted */ | |
2528 | struct task_struct *latest_task = NULL; | |
2529 | struct ptr_heap tmp_heap; | |
2530 | struct ptr_heap *heap; | |
2531 | struct timespec latest_time = { 0, 0 }; | |
2532 | ||
2533 | if (scan->heap) { | |
2534 | /* The caller supplied our heap and pre-allocated its memory */ | |
2535 | heap = scan->heap; | |
2536 | heap->gt = &started_after; | |
2537 | } else { | |
2538 | /* We need to allocate our own heap memory */ | |
2539 | heap = &tmp_heap; | |
2540 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
2541 | if (retval) | |
2542 | /* cannot allocate the heap */ | |
2543 | return retval; | |
2544 | } | |
2545 | ||
2546 | again: | |
2547 | /* | |
2548 | * Scan tasks in the cgroup, using the scanner's "test_task" callback | |
2549 | * to determine which are of interest, and using the scanner's | |
2550 | * "process_task" callback to process any of them that need an update. | |
2551 | * Since we don't want to hold any locks during the task updates, | |
2552 | * gather tasks to be processed in a heap structure. | |
2553 | * The heap is sorted by descending task start time. | |
2554 | * If the statically-sized heap fills up, we overflow tasks that | |
2555 | * started later, and in future iterations only consider tasks that | |
2556 | * started after the latest task in the previous pass. This | |
2557 | * guarantees forward progress and that we don't miss any tasks. | |
2558 | */ | |
2559 | heap->size = 0; | |
2560 | cgroup_iter_start(scan->cg, &it); | |
2561 | while ((p = cgroup_iter_next(scan->cg, &it))) { | |
2562 | /* | |
2563 | * Only affect tasks that qualify per the caller's callback, | |
2564 | * if he provided one | |
2565 | */ | |
2566 | if (scan->test_task && !scan->test_task(p, scan)) | |
2567 | continue; | |
2568 | /* | |
2569 | * Only process tasks that started after the last task | |
2570 | * we processed | |
2571 | */ | |
2572 | if (!started_after_time(p, &latest_time, latest_task)) | |
2573 | continue; | |
2574 | dropped = heap_insert(heap, p); | |
2575 | if (dropped == NULL) { | |
2576 | /* | |
2577 | * The new task was inserted; the heap wasn't | |
2578 | * previously full | |
2579 | */ | |
2580 | get_task_struct(p); | |
2581 | } else if (dropped != p) { | |
2582 | /* | |
2583 | * The new task was inserted, and pushed out a | |
2584 | * different task | |
2585 | */ | |
2586 | get_task_struct(p); | |
2587 | put_task_struct(dropped); | |
2588 | } | |
2589 | /* | |
2590 | * Else the new task was newer than anything already in | |
2591 | * the heap and wasn't inserted | |
2592 | */ | |
2593 | } | |
2594 | cgroup_iter_end(scan->cg, &it); | |
2595 | ||
2596 | if (heap->size) { | |
2597 | for (i = 0; i < heap->size; i++) { | |
4fe91d51 | 2598 | struct task_struct *q = heap->ptrs[i]; |
31a7df01 | 2599 | if (i == 0) { |
4fe91d51 PJ |
2600 | latest_time = q->start_time; |
2601 | latest_task = q; | |
31a7df01 CW |
2602 | } |
2603 | /* Process the task per the caller's callback */ | |
4fe91d51 PJ |
2604 | scan->process_task(q, scan); |
2605 | put_task_struct(q); | |
31a7df01 CW |
2606 | } |
2607 | /* | |
2608 | * If we had to process any tasks at all, scan again | |
2609 | * in case some of them were in the middle of forking | |
2610 | * children that didn't get processed. | |
2611 | * Not the most efficient way to do it, but it avoids | |
2612 | * having to take callback_mutex in the fork path | |
2613 | */ | |
2614 | goto again; | |
2615 | } | |
2616 | if (heap == &tmp_heap) | |
2617 | heap_free(&tmp_heap); | |
2618 | return 0; | |
2619 | } | |
2620 | ||
bbcb81d0 | 2621 | /* |
102a775e | 2622 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
2623 | * |
2624 | * Reading this file can return large amounts of data if a cgroup has | |
2625 | * *lots* of attached tasks. So it may need several calls to read(), | |
2626 | * but we cannot guarantee that the information we produce is correct | |
2627 | * unless we produce it entirely atomically. | |
2628 | * | |
bbcb81d0 | 2629 | */ |
bbcb81d0 | 2630 | |
d1d9fd33 BB |
2631 | /* |
2632 | * The following two functions "fix" the issue where there are more pids | |
2633 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
2634 | * TODO: replace with a kernel-wide solution to this problem | |
2635 | */ | |
2636 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
2637 | static void *pidlist_allocate(int count) | |
2638 | { | |
2639 | if (PIDLIST_TOO_LARGE(count)) | |
2640 | return vmalloc(count * sizeof(pid_t)); | |
2641 | else | |
2642 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
2643 | } | |
2644 | static void pidlist_free(void *p) | |
2645 | { | |
2646 | if (is_vmalloc_addr(p)) | |
2647 | vfree(p); | |
2648 | else | |
2649 | kfree(p); | |
2650 | } | |
2651 | static void *pidlist_resize(void *p, int newcount) | |
2652 | { | |
2653 | void *newlist; | |
2654 | /* note: if new alloc fails, old p will still be valid either way */ | |
2655 | if (is_vmalloc_addr(p)) { | |
2656 | newlist = vmalloc(newcount * sizeof(pid_t)); | |
2657 | if (!newlist) | |
2658 | return NULL; | |
2659 | memcpy(newlist, p, newcount * sizeof(pid_t)); | |
2660 | vfree(p); | |
2661 | } else { | |
2662 | newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); | |
2663 | } | |
2664 | return newlist; | |
2665 | } | |
2666 | ||
bbcb81d0 | 2667 | /* |
102a775e BB |
2668 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
2669 | * If the new stripped list is sufficiently smaller and there's enough memory | |
2670 | * to allocate a new buffer, will let go of the unneeded memory. Returns the | |
2671 | * number of unique elements. | |
bbcb81d0 | 2672 | */ |
102a775e BB |
2673 | /* is the size difference enough that we should re-allocate the array? */ |
2674 | #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) | |
2675 | static int pidlist_uniq(pid_t **p, int length) | |
bbcb81d0 | 2676 | { |
102a775e BB |
2677 | int src, dest = 1; |
2678 | pid_t *list = *p; | |
2679 | pid_t *newlist; | |
2680 | ||
2681 | /* | |
2682 | * we presume the 0th element is unique, so i starts at 1. trivial | |
2683 | * edge cases first; no work needs to be done for either | |
2684 | */ | |
2685 | if (length == 0 || length == 1) | |
2686 | return length; | |
2687 | /* src and dest walk down the list; dest counts unique elements */ | |
2688 | for (src = 1; src < length; src++) { | |
2689 | /* find next unique element */ | |
2690 | while (list[src] == list[src-1]) { | |
2691 | src++; | |
2692 | if (src == length) | |
2693 | goto after; | |
2694 | } | |
2695 | /* dest always points to where the next unique element goes */ | |
2696 | list[dest] = list[src]; | |
2697 | dest++; | |
2698 | } | |
2699 | after: | |
2700 | /* | |
2701 | * if the length difference is large enough, we want to allocate a | |
2702 | * smaller buffer to save memory. if this fails due to out of memory, | |
2703 | * we'll just stay with what we've got. | |
2704 | */ | |
2705 | if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { | |
d1d9fd33 | 2706 | newlist = pidlist_resize(list, dest); |
102a775e BB |
2707 | if (newlist) |
2708 | *p = newlist; | |
2709 | } | |
2710 | return dest; | |
2711 | } | |
2712 | ||
2713 | static int cmppid(const void *a, const void *b) | |
2714 | { | |
2715 | return *(pid_t *)a - *(pid_t *)b; | |
2716 | } | |
2717 | ||
72a8cb30 BB |
2718 | /* |
2719 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
2720 | * returns with the lock on that pidlist already held, and takes care | |
2721 | * of the use count, or returns NULL with no locks held if we're out of | |
2722 | * memory. | |
2723 | */ | |
2724 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, | |
2725 | enum cgroup_filetype type) | |
2726 | { | |
2727 | struct cgroup_pidlist *l; | |
2728 | /* don't need task_nsproxy() if we're looking at ourself */ | |
b70cc5fd LZ |
2729 | struct pid_namespace *ns = current->nsproxy->pid_ns; |
2730 | ||
72a8cb30 BB |
2731 | /* |
2732 | * We can't drop the pidlist_mutex before taking the l->mutex in case | |
2733 | * the last ref-holder is trying to remove l from the list at the same | |
2734 | * time. Holding the pidlist_mutex precludes somebody taking whichever | |
2735 | * list we find out from under us - compare release_pid_array(). | |
2736 | */ | |
2737 | mutex_lock(&cgrp->pidlist_mutex); | |
2738 | list_for_each_entry(l, &cgrp->pidlists, links) { | |
2739 | if (l->key.type == type && l->key.ns == ns) { | |
72a8cb30 BB |
2740 | /* make sure l doesn't vanish out from under us */ |
2741 | down_write(&l->mutex); | |
2742 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
2743 | return l; |
2744 | } | |
2745 | } | |
2746 | /* entry not found; create a new one */ | |
2747 | l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); | |
2748 | if (!l) { | |
2749 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
2750 | return l; |
2751 | } | |
2752 | init_rwsem(&l->mutex); | |
2753 | down_write(&l->mutex); | |
2754 | l->key.type = type; | |
b70cc5fd | 2755 | l->key.ns = get_pid_ns(ns); |
72a8cb30 BB |
2756 | l->use_count = 0; /* don't increment here */ |
2757 | l->list = NULL; | |
2758 | l->owner = cgrp; | |
2759 | list_add(&l->links, &cgrp->pidlists); | |
2760 | mutex_unlock(&cgrp->pidlist_mutex); | |
2761 | return l; | |
2762 | } | |
2763 | ||
102a775e BB |
2764 | /* |
2765 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
2766 | */ | |
72a8cb30 BB |
2767 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
2768 | struct cgroup_pidlist **lp) | |
102a775e BB |
2769 | { |
2770 | pid_t *array; | |
2771 | int length; | |
2772 | int pid, n = 0; /* used for populating the array */ | |
817929ec PM |
2773 | struct cgroup_iter it; |
2774 | struct task_struct *tsk; | |
102a775e BB |
2775 | struct cgroup_pidlist *l; |
2776 | ||
2777 | /* | |
2778 | * If cgroup gets more users after we read count, we won't have | |
2779 | * enough space - tough. This race is indistinguishable to the | |
2780 | * caller from the case that the additional cgroup users didn't | |
2781 | * show up until sometime later on. | |
2782 | */ | |
2783 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 2784 | array = pidlist_allocate(length); |
102a775e BB |
2785 | if (!array) |
2786 | return -ENOMEM; | |
2787 | /* now, populate the array */ | |
bd89aabc PM |
2788 | cgroup_iter_start(cgrp, &it); |
2789 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
102a775e | 2790 | if (unlikely(n == length)) |
817929ec | 2791 | break; |
102a775e | 2792 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
2793 | if (type == CGROUP_FILE_PROCS) |
2794 | pid = task_tgid_vnr(tsk); | |
2795 | else | |
2796 | pid = task_pid_vnr(tsk); | |
102a775e BB |
2797 | if (pid > 0) /* make sure to only use valid results */ |
2798 | array[n++] = pid; | |
817929ec | 2799 | } |
bd89aabc | 2800 | cgroup_iter_end(cgrp, &it); |
102a775e BB |
2801 | length = n; |
2802 | /* now sort & (if procs) strip out duplicates */ | |
2803 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 2804 | if (type == CGROUP_FILE_PROCS) |
102a775e | 2805 | length = pidlist_uniq(&array, length); |
72a8cb30 BB |
2806 | l = cgroup_pidlist_find(cgrp, type); |
2807 | if (!l) { | |
d1d9fd33 | 2808 | pidlist_free(array); |
72a8cb30 | 2809 | return -ENOMEM; |
102a775e | 2810 | } |
72a8cb30 | 2811 | /* store array, freeing old if necessary - lock already held */ |
d1d9fd33 | 2812 | pidlist_free(l->list); |
102a775e BB |
2813 | l->list = array; |
2814 | l->length = length; | |
2815 | l->use_count++; | |
2816 | up_write(&l->mutex); | |
72a8cb30 | 2817 | *lp = l; |
102a775e | 2818 | return 0; |
bbcb81d0 PM |
2819 | } |
2820 | ||
846c7bb0 | 2821 | /** |
a043e3b2 | 2822 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
2823 | * @stats: cgroupstats to fill information into |
2824 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
2825 | * been requested. | |
a043e3b2 LZ |
2826 | * |
2827 | * Build and fill cgroupstats so that taskstats can export it to user | |
2828 | * space. | |
846c7bb0 BS |
2829 | */ |
2830 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
2831 | { | |
2832 | int ret = -EINVAL; | |
bd89aabc | 2833 | struct cgroup *cgrp; |
846c7bb0 BS |
2834 | struct cgroup_iter it; |
2835 | struct task_struct *tsk; | |
33d283be | 2836 | |
846c7bb0 | 2837 | /* |
33d283be LZ |
2838 | * Validate dentry by checking the superblock operations, |
2839 | * and make sure it's a directory. | |
846c7bb0 | 2840 | */ |
33d283be LZ |
2841 | if (dentry->d_sb->s_op != &cgroup_ops || |
2842 | !S_ISDIR(dentry->d_inode->i_mode)) | |
846c7bb0 BS |
2843 | goto err; |
2844 | ||
2845 | ret = 0; | |
bd89aabc | 2846 | cgrp = dentry->d_fsdata; |
846c7bb0 | 2847 | |
bd89aabc PM |
2848 | cgroup_iter_start(cgrp, &it); |
2849 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
846c7bb0 BS |
2850 | switch (tsk->state) { |
2851 | case TASK_RUNNING: | |
2852 | stats->nr_running++; | |
2853 | break; | |
2854 | case TASK_INTERRUPTIBLE: | |
2855 | stats->nr_sleeping++; | |
2856 | break; | |
2857 | case TASK_UNINTERRUPTIBLE: | |
2858 | stats->nr_uninterruptible++; | |
2859 | break; | |
2860 | case TASK_STOPPED: | |
2861 | stats->nr_stopped++; | |
2862 | break; | |
2863 | default: | |
2864 | if (delayacct_is_task_waiting_on_io(tsk)) | |
2865 | stats->nr_io_wait++; | |
2866 | break; | |
2867 | } | |
2868 | } | |
bd89aabc | 2869 | cgroup_iter_end(cgrp, &it); |
846c7bb0 | 2870 | |
846c7bb0 BS |
2871 | err: |
2872 | return ret; | |
2873 | } | |
2874 | ||
8f3ff208 | 2875 | |
bbcb81d0 | 2876 | /* |
102a775e | 2877 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 2878 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 2879 | * in the cgroup->l->list array. |
bbcb81d0 | 2880 | */ |
cc31edce | 2881 | |
102a775e | 2882 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 2883 | { |
cc31edce PM |
2884 | /* |
2885 | * Initially we receive a position value that corresponds to | |
2886 | * one more than the last pid shown (or 0 on the first call or | |
2887 | * after a seek to the start). Use a binary-search to find the | |
2888 | * next pid to display, if any | |
2889 | */ | |
102a775e | 2890 | struct cgroup_pidlist *l = s->private; |
cc31edce PM |
2891 | int index = 0, pid = *pos; |
2892 | int *iter; | |
2893 | ||
102a775e | 2894 | down_read(&l->mutex); |
cc31edce | 2895 | if (pid) { |
102a775e | 2896 | int end = l->length; |
20777766 | 2897 | |
cc31edce PM |
2898 | while (index < end) { |
2899 | int mid = (index + end) / 2; | |
102a775e | 2900 | if (l->list[mid] == pid) { |
cc31edce PM |
2901 | index = mid; |
2902 | break; | |
102a775e | 2903 | } else if (l->list[mid] <= pid) |
cc31edce PM |
2904 | index = mid + 1; |
2905 | else | |
2906 | end = mid; | |
2907 | } | |
2908 | } | |
2909 | /* If we're off the end of the array, we're done */ | |
102a775e | 2910 | if (index >= l->length) |
cc31edce PM |
2911 | return NULL; |
2912 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 2913 | iter = l->list + index; |
cc31edce PM |
2914 | *pos = *iter; |
2915 | return iter; | |
2916 | } | |
2917 | ||
102a775e | 2918 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 2919 | { |
102a775e BB |
2920 | struct cgroup_pidlist *l = s->private; |
2921 | up_read(&l->mutex); | |
cc31edce PM |
2922 | } |
2923 | ||
102a775e | 2924 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 2925 | { |
102a775e BB |
2926 | struct cgroup_pidlist *l = s->private; |
2927 | pid_t *p = v; | |
2928 | pid_t *end = l->list + l->length; | |
cc31edce PM |
2929 | /* |
2930 | * Advance to the next pid in the array. If this goes off the | |
2931 | * end, we're done | |
2932 | */ | |
2933 | p++; | |
2934 | if (p >= end) { | |
2935 | return NULL; | |
2936 | } else { | |
2937 | *pos = *p; | |
2938 | return p; | |
2939 | } | |
2940 | } | |
2941 | ||
102a775e | 2942 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
2943 | { |
2944 | return seq_printf(s, "%d\n", *(int *)v); | |
2945 | } | |
bbcb81d0 | 2946 | |
102a775e BB |
2947 | /* |
2948 | * seq_operations functions for iterating on pidlists through seq_file - | |
2949 | * independent of whether it's tasks or procs | |
2950 | */ | |
2951 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
2952 | .start = cgroup_pidlist_start, | |
2953 | .stop = cgroup_pidlist_stop, | |
2954 | .next = cgroup_pidlist_next, | |
2955 | .show = cgroup_pidlist_show, | |
cc31edce PM |
2956 | }; |
2957 | ||
102a775e | 2958 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
cc31edce | 2959 | { |
72a8cb30 BB |
2960 | /* |
2961 | * the case where we're the last user of this particular pidlist will | |
2962 | * have us remove it from the cgroup's list, which entails taking the | |
2963 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> | |
2964 | * pidlist_mutex, we have to take pidlist_mutex first. | |
2965 | */ | |
2966 | mutex_lock(&l->owner->pidlist_mutex); | |
102a775e BB |
2967 | down_write(&l->mutex); |
2968 | BUG_ON(!l->use_count); | |
2969 | if (!--l->use_count) { | |
72a8cb30 BB |
2970 | /* we're the last user if refcount is 0; remove and free */ |
2971 | list_del(&l->links); | |
2972 | mutex_unlock(&l->owner->pidlist_mutex); | |
d1d9fd33 | 2973 | pidlist_free(l->list); |
72a8cb30 BB |
2974 | put_pid_ns(l->key.ns); |
2975 | up_write(&l->mutex); | |
2976 | kfree(l); | |
2977 | return; | |
cc31edce | 2978 | } |
72a8cb30 | 2979 | mutex_unlock(&l->owner->pidlist_mutex); |
102a775e | 2980 | up_write(&l->mutex); |
bbcb81d0 PM |
2981 | } |
2982 | ||
102a775e | 2983 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
cc31edce | 2984 | { |
102a775e | 2985 | struct cgroup_pidlist *l; |
cc31edce PM |
2986 | if (!(file->f_mode & FMODE_READ)) |
2987 | return 0; | |
102a775e BB |
2988 | /* |
2989 | * the seq_file will only be initialized if the file was opened for | |
2990 | * reading; hence we check if it's not null only in that case. | |
2991 | */ | |
2992 | l = ((struct seq_file *)file->private_data)->private; | |
2993 | cgroup_release_pid_array(l); | |
cc31edce PM |
2994 | return seq_release(inode, file); |
2995 | } | |
2996 | ||
102a775e | 2997 | static const struct file_operations cgroup_pidlist_operations = { |
cc31edce PM |
2998 | .read = seq_read, |
2999 | .llseek = seq_lseek, | |
3000 | .write = cgroup_file_write, | |
102a775e | 3001 | .release = cgroup_pidlist_release, |
cc31edce PM |
3002 | }; |
3003 | ||
bbcb81d0 | 3004 | /* |
102a775e BB |
3005 | * The following functions handle opens on a file that displays a pidlist |
3006 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's | |
3007 | * in the cgroup. | |
bbcb81d0 | 3008 | */ |
102a775e | 3009 | /* helper function for the two below it */ |
72a8cb30 | 3010 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
bbcb81d0 | 3011 | { |
bd89aabc | 3012 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
72a8cb30 | 3013 | struct cgroup_pidlist *l; |
cc31edce | 3014 | int retval; |
bbcb81d0 | 3015 | |
cc31edce | 3016 | /* Nothing to do for write-only files */ |
bbcb81d0 PM |
3017 | if (!(file->f_mode & FMODE_READ)) |
3018 | return 0; | |
3019 | ||
102a775e | 3020 | /* have the array populated */ |
72a8cb30 | 3021 | retval = pidlist_array_load(cgrp, type, &l); |
102a775e BB |
3022 | if (retval) |
3023 | return retval; | |
3024 | /* configure file information */ | |
3025 | file->f_op = &cgroup_pidlist_operations; | |
cc31edce | 3026 | |
102a775e | 3027 | retval = seq_open(file, &cgroup_pidlist_seq_operations); |
cc31edce | 3028 | if (retval) { |
102a775e | 3029 | cgroup_release_pid_array(l); |
cc31edce | 3030 | return retval; |
bbcb81d0 | 3031 | } |
102a775e | 3032 | ((struct seq_file *)file->private_data)->private = l; |
bbcb81d0 PM |
3033 | return 0; |
3034 | } | |
102a775e BB |
3035 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
3036 | { | |
72a8cb30 | 3037 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
102a775e BB |
3038 | } |
3039 | static int cgroup_procs_open(struct inode *unused, struct file *file) | |
3040 | { | |
72a8cb30 | 3041 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
102a775e | 3042 | } |
bbcb81d0 | 3043 | |
bd89aabc | 3044 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
81a6a5cd PM |
3045 | struct cftype *cft) |
3046 | { | |
bd89aabc | 3047 | return notify_on_release(cgrp); |
81a6a5cd PM |
3048 | } |
3049 | ||
6379c106 PM |
3050 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
3051 | struct cftype *cft, | |
3052 | u64 val) | |
3053 | { | |
3054 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); | |
3055 | if (val) | |
3056 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3057 | else | |
3058 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3059 | return 0; | |
3060 | } | |
3061 | ||
0dea1168 KS |
3062 | /* |
3063 | * Unregister event and free resources. | |
3064 | * | |
3065 | * Gets called from workqueue. | |
3066 | */ | |
3067 | static void cgroup_event_remove(struct work_struct *work) | |
3068 | { | |
3069 | struct cgroup_event *event = container_of(work, struct cgroup_event, | |
3070 | remove); | |
3071 | struct cgroup *cgrp = event->cgrp; | |
3072 | ||
0dea1168 KS |
3073 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3074 | ||
3075 | eventfd_ctx_put(event->eventfd); | |
0dea1168 | 3076 | kfree(event); |
a0a4db54 | 3077 | dput(cgrp->dentry); |
0dea1168 KS |
3078 | } |
3079 | ||
3080 | /* | |
3081 | * Gets called on POLLHUP on eventfd when user closes it. | |
3082 | * | |
3083 | * Called with wqh->lock held and interrupts disabled. | |
3084 | */ | |
3085 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, | |
3086 | int sync, void *key) | |
3087 | { | |
3088 | struct cgroup_event *event = container_of(wait, | |
3089 | struct cgroup_event, wait); | |
3090 | struct cgroup *cgrp = event->cgrp; | |
3091 | unsigned long flags = (unsigned long)key; | |
3092 | ||
3093 | if (flags & POLLHUP) { | |
a93d2f17 | 3094 | __remove_wait_queue(event->wqh, &event->wait); |
0dea1168 KS |
3095 | spin_lock(&cgrp->event_list_lock); |
3096 | list_del(&event->list); | |
3097 | spin_unlock(&cgrp->event_list_lock); | |
3098 | /* | |
3099 | * We are in atomic context, but cgroup_event_remove() may | |
3100 | * sleep, so we have to call it in workqueue. | |
3101 | */ | |
3102 | schedule_work(&event->remove); | |
3103 | } | |
3104 | ||
3105 | return 0; | |
3106 | } | |
3107 | ||
3108 | static void cgroup_event_ptable_queue_proc(struct file *file, | |
3109 | wait_queue_head_t *wqh, poll_table *pt) | |
3110 | { | |
3111 | struct cgroup_event *event = container_of(pt, | |
3112 | struct cgroup_event, pt); | |
3113 | ||
3114 | event->wqh = wqh; | |
3115 | add_wait_queue(wqh, &event->wait); | |
3116 | } | |
3117 | ||
3118 | /* | |
3119 | * Parse input and register new cgroup event handler. | |
3120 | * | |
3121 | * Input must be in format '<event_fd> <control_fd> <args>'. | |
3122 | * Interpretation of args is defined by control file implementation. | |
3123 | */ | |
3124 | static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, | |
3125 | const char *buffer) | |
3126 | { | |
3127 | struct cgroup_event *event = NULL; | |
3128 | unsigned int efd, cfd; | |
3129 | struct file *efile = NULL; | |
3130 | struct file *cfile = NULL; | |
3131 | char *endp; | |
3132 | int ret; | |
3133 | ||
3134 | efd = simple_strtoul(buffer, &endp, 10); | |
3135 | if (*endp != ' ') | |
3136 | return -EINVAL; | |
3137 | buffer = endp + 1; | |
3138 | ||
3139 | cfd = simple_strtoul(buffer, &endp, 10); | |
3140 | if ((*endp != ' ') && (*endp != '\0')) | |
3141 | return -EINVAL; | |
3142 | buffer = endp + 1; | |
3143 | ||
3144 | event = kzalloc(sizeof(*event), GFP_KERNEL); | |
3145 | if (!event) | |
3146 | return -ENOMEM; | |
3147 | event->cgrp = cgrp; | |
3148 | INIT_LIST_HEAD(&event->list); | |
3149 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); | |
3150 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); | |
3151 | INIT_WORK(&event->remove, cgroup_event_remove); | |
3152 | ||
3153 | efile = eventfd_fget(efd); | |
3154 | if (IS_ERR(efile)) { | |
3155 | ret = PTR_ERR(efile); | |
3156 | goto fail; | |
3157 | } | |
3158 | ||
3159 | event->eventfd = eventfd_ctx_fileget(efile); | |
3160 | if (IS_ERR(event->eventfd)) { | |
3161 | ret = PTR_ERR(event->eventfd); | |
3162 | goto fail; | |
3163 | } | |
3164 | ||
3165 | cfile = fget(cfd); | |
3166 | if (!cfile) { | |
3167 | ret = -EBADF; | |
3168 | goto fail; | |
3169 | } | |
3170 | ||
3171 | /* the process need read permission on control file */ | |
3172 | ret = file_permission(cfile, MAY_READ); | |
3173 | if (ret < 0) | |
3174 | goto fail; | |
3175 | ||
3176 | event->cft = __file_cft(cfile); | |
3177 | if (IS_ERR(event->cft)) { | |
3178 | ret = PTR_ERR(event->cft); | |
3179 | goto fail; | |
3180 | } | |
3181 | ||
3182 | if (!event->cft->register_event || !event->cft->unregister_event) { | |
3183 | ret = -EINVAL; | |
3184 | goto fail; | |
3185 | } | |
3186 | ||
3187 | ret = event->cft->register_event(cgrp, event->cft, | |
3188 | event->eventfd, buffer); | |
3189 | if (ret) | |
3190 | goto fail; | |
3191 | ||
3192 | if (efile->f_op->poll(efile, &event->pt) & POLLHUP) { | |
3193 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); | |
3194 | ret = 0; | |
3195 | goto fail; | |
3196 | } | |
3197 | ||
a0a4db54 KS |
3198 | /* |
3199 | * Events should be removed after rmdir of cgroup directory, but before | |
3200 | * destroying subsystem state objects. Let's take reference to cgroup | |
3201 | * directory dentry to do that. | |
3202 | */ | |
3203 | dget(cgrp->dentry); | |
3204 | ||
0dea1168 KS |
3205 | spin_lock(&cgrp->event_list_lock); |
3206 | list_add(&event->list, &cgrp->event_list); | |
3207 | spin_unlock(&cgrp->event_list_lock); | |
3208 | ||
3209 | fput(cfile); | |
3210 | fput(efile); | |
3211 | ||
3212 | return 0; | |
3213 | ||
3214 | fail: | |
3215 | if (cfile) | |
3216 | fput(cfile); | |
3217 | ||
3218 | if (event && event->eventfd && !IS_ERR(event->eventfd)) | |
3219 | eventfd_ctx_put(event->eventfd); | |
3220 | ||
3221 | if (!IS_ERR_OR_NULL(efile)) | |
3222 | fput(efile); | |
3223 | ||
3224 | kfree(event); | |
3225 | ||
3226 | return ret; | |
3227 | } | |
3228 | ||
97978e6d DL |
3229 | static u64 cgroup_clone_children_read(struct cgroup *cgrp, |
3230 | struct cftype *cft) | |
3231 | { | |
3232 | return clone_children(cgrp); | |
3233 | } | |
3234 | ||
3235 | static int cgroup_clone_children_write(struct cgroup *cgrp, | |
3236 | struct cftype *cft, | |
3237 | u64 val) | |
3238 | { | |
3239 | if (val) | |
3240 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3241 | else | |
3242 | clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3243 | return 0; | |
3244 | } | |
3245 | ||
bbcb81d0 PM |
3246 | /* |
3247 | * for the common functions, 'private' gives the type of file | |
3248 | */ | |
102a775e BB |
3249 | /* for hysterical raisins, we can't put this on the older files */ |
3250 | #define CGROUP_FILE_GENERIC_PREFIX "cgroup." | |
81a6a5cd PM |
3251 | static struct cftype files[] = { |
3252 | { | |
3253 | .name = "tasks", | |
3254 | .open = cgroup_tasks_open, | |
af351026 | 3255 | .write_u64 = cgroup_tasks_write, |
102a775e | 3256 | .release = cgroup_pidlist_release, |
099fca32 | 3257 | .mode = S_IRUGO | S_IWUSR, |
81a6a5cd | 3258 | }, |
102a775e BB |
3259 | { |
3260 | .name = CGROUP_FILE_GENERIC_PREFIX "procs", | |
3261 | .open = cgroup_procs_open, | |
3262 | /* .write_u64 = cgroup_procs_write, TODO */ | |
3263 | .release = cgroup_pidlist_release, | |
3264 | .mode = S_IRUGO, | |
3265 | }, | |
81a6a5cd PM |
3266 | { |
3267 | .name = "notify_on_release", | |
f4c753b7 | 3268 | .read_u64 = cgroup_read_notify_on_release, |
6379c106 | 3269 | .write_u64 = cgroup_write_notify_on_release, |
81a6a5cd | 3270 | }, |
0dea1168 KS |
3271 | { |
3272 | .name = CGROUP_FILE_GENERIC_PREFIX "event_control", | |
3273 | .write_string = cgroup_write_event_control, | |
3274 | .mode = S_IWUGO, | |
3275 | }, | |
97978e6d DL |
3276 | { |
3277 | .name = "cgroup.clone_children", | |
3278 | .read_u64 = cgroup_clone_children_read, | |
3279 | .write_u64 = cgroup_clone_children_write, | |
3280 | }, | |
81a6a5cd PM |
3281 | }; |
3282 | ||
3283 | static struct cftype cft_release_agent = { | |
3284 | .name = "release_agent", | |
e788e066 PM |
3285 | .read_seq_string = cgroup_release_agent_show, |
3286 | .write_string = cgroup_release_agent_write, | |
3287 | .max_write_len = PATH_MAX, | |
bbcb81d0 PM |
3288 | }; |
3289 | ||
bd89aabc | 3290 | static int cgroup_populate_dir(struct cgroup *cgrp) |
ddbcc7e8 PM |
3291 | { |
3292 | int err; | |
3293 | struct cgroup_subsys *ss; | |
3294 | ||
3295 | /* First clear out any existing files */ | |
bd89aabc | 3296 | cgroup_clear_directory(cgrp->dentry); |
ddbcc7e8 | 3297 | |
bd89aabc | 3298 | err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files)); |
bbcb81d0 PM |
3299 | if (err < 0) |
3300 | return err; | |
3301 | ||
bd89aabc PM |
3302 | if (cgrp == cgrp->top_cgroup) { |
3303 | if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0) | |
81a6a5cd PM |
3304 | return err; |
3305 | } | |
3306 | ||
bd89aabc PM |
3307 | for_each_subsys(cgrp->root, ss) { |
3308 | if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) | |
ddbcc7e8 PM |
3309 | return err; |
3310 | } | |
38460b48 KH |
3311 | /* This cgroup is ready now */ |
3312 | for_each_subsys(cgrp->root, ss) { | |
3313 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3314 | /* | |
3315 | * Update id->css pointer and make this css visible from | |
3316 | * CSS ID functions. This pointer will be dereferened | |
3317 | * from RCU-read-side without locks. | |
3318 | */ | |
3319 | if (css->id) | |
3320 | rcu_assign_pointer(css->id->css, css); | |
3321 | } | |
ddbcc7e8 PM |
3322 | |
3323 | return 0; | |
3324 | } | |
3325 | ||
3326 | static void init_cgroup_css(struct cgroup_subsys_state *css, | |
3327 | struct cgroup_subsys *ss, | |
bd89aabc | 3328 | struct cgroup *cgrp) |
ddbcc7e8 | 3329 | { |
bd89aabc | 3330 | css->cgroup = cgrp; |
e7c5ec91 | 3331 | atomic_set(&css->refcnt, 1); |
ddbcc7e8 | 3332 | css->flags = 0; |
38460b48 | 3333 | css->id = NULL; |
bd89aabc | 3334 | if (cgrp == dummytop) |
ddbcc7e8 | 3335 | set_bit(CSS_ROOT, &css->flags); |
bd89aabc PM |
3336 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
3337 | cgrp->subsys[ss->subsys_id] = css; | |
ddbcc7e8 PM |
3338 | } |
3339 | ||
999cd8a4 PM |
3340 | static void cgroup_lock_hierarchy(struct cgroupfs_root *root) |
3341 | { | |
3342 | /* We need to take each hierarchy_mutex in a consistent order */ | |
3343 | int i; | |
3344 | ||
aae8aab4 BB |
3345 | /* |
3346 | * No worry about a race with rebind_subsystems that might mess up the | |
3347 | * locking order, since both parties are under cgroup_mutex. | |
3348 | */ | |
999cd8a4 PM |
3349 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3350 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
3351 | if (ss == NULL) |
3352 | continue; | |
999cd8a4 | 3353 | if (ss->root == root) |
cfebe563 | 3354 | mutex_lock(&ss->hierarchy_mutex); |
999cd8a4 PM |
3355 | } |
3356 | } | |
3357 | ||
3358 | static void cgroup_unlock_hierarchy(struct cgroupfs_root *root) | |
3359 | { | |
3360 | int i; | |
3361 | ||
3362 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
3363 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
3364 | if (ss == NULL) |
3365 | continue; | |
999cd8a4 PM |
3366 | if (ss->root == root) |
3367 | mutex_unlock(&ss->hierarchy_mutex); | |
3368 | } | |
3369 | } | |
3370 | ||
ddbcc7e8 | 3371 | /* |
a043e3b2 LZ |
3372 | * cgroup_create - create a cgroup |
3373 | * @parent: cgroup that will be parent of the new cgroup | |
3374 | * @dentry: dentry of the new cgroup | |
3375 | * @mode: mode to set on new inode | |
ddbcc7e8 | 3376 | * |
a043e3b2 | 3377 | * Must be called with the mutex on the parent inode held |
ddbcc7e8 | 3378 | */ |
ddbcc7e8 | 3379 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
099fca32 | 3380 | mode_t mode) |
ddbcc7e8 | 3381 | { |
bd89aabc | 3382 | struct cgroup *cgrp; |
ddbcc7e8 PM |
3383 | struct cgroupfs_root *root = parent->root; |
3384 | int err = 0; | |
3385 | struct cgroup_subsys *ss; | |
3386 | struct super_block *sb = root->sb; | |
3387 | ||
bd89aabc PM |
3388 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
3389 | if (!cgrp) | |
ddbcc7e8 PM |
3390 | return -ENOMEM; |
3391 | ||
3392 | /* Grab a reference on the superblock so the hierarchy doesn't | |
3393 | * get deleted on unmount if there are child cgroups. This | |
3394 | * can be done outside cgroup_mutex, since the sb can't | |
3395 | * disappear while someone has an open control file on the | |
3396 | * fs */ | |
3397 | atomic_inc(&sb->s_active); | |
3398 | ||
3399 | mutex_lock(&cgroup_mutex); | |
3400 | ||
cc31edce | 3401 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 3402 | |
bd89aabc PM |
3403 | cgrp->parent = parent; |
3404 | cgrp->root = parent->root; | |
3405 | cgrp->top_cgroup = parent->top_cgroup; | |
ddbcc7e8 | 3406 | |
b6abdb0e LZ |
3407 | if (notify_on_release(parent)) |
3408 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3409 | ||
97978e6d DL |
3410 | if (clone_children(parent)) |
3411 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3412 | ||
ddbcc7e8 | 3413 | for_each_subsys(root, ss) { |
bd89aabc | 3414 | struct cgroup_subsys_state *css = ss->create(ss, cgrp); |
4528fd05 | 3415 | |
ddbcc7e8 PM |
3416 | if (IS_ERR(css)) { |
3417 | err = PTR_ERR(css); | |
3418 | goto err_destroy; | |
3419 | } | |
bd89aabc | 3420 | init_cgroup_css(css, ss, cgrp); |
4528fd05 LZ |
3421 | if (ss->use_id) { |
3422 | err = alloc_css_id(ss, parent, cgrp); | |
3423 | if (err) | |
38460b48 | 3424 | goto err_destroy; |
4528fd05 | 3425 | } |
38460b48 | 3426 | /* At error, ->destroy() callback has to free assigned ID. */ |
97978e6d DL |
3427 | if (clone_children(parent) && ss->post_clone) |
3428 | ss->post_clone(ss, cgrp); | |
ddbcc7e8 PM |
3429 | } |
3430 | ||
999cd8a4 | 3431 | cgroup_lock_hierarchy(root); |
bd89aabc | 3432 | list_add(&cgrp->sibling, &cgrp->parent->children); |
999cd8a4 | 3433 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
3434 | root->number_of_cgroups++; |
3435 | ||
bd89aabc | 3436 | err = cgroup_create_dir(cgrp, dentry, mode); |
ddbcc7e8 PM |
3437 | if (err < 0) |
3438 | goto err_remove; | |
3439 | ||
3440 | /* The cgroup directory was pre-locked for us */ | |
bd89aabc | 3441 | BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); |
ddbcc7e8 | 3442 | |
bd89aabc | 3443 | err = cgroup_populate_dir(cgrp); |
ddbcc7e8 PM |
3444 | /* If err < 0, we have a half-filled directory - oh well ;) */ |
3445 | ||
3446 | mutex_unlock(&cgroup_mutex); | |
bd89aabc | 3447 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
3448 | |
3449 | return 0; | |
3450 | ||
3451 | err_remove: | |
3452 | ||
baef99a0 | 3453 | cgroup_lock_hierarchy(root); |
bd89aabc | 3454 | list_del(&cgrp->sibling); |
baef99a0 | 3455 | cgroup_unlock_hierarchy(root); |
ddbcc7e8 PM |
3456 | root->number_of_cgroups--; |
3457 | ||
3458 | err_destroy: | |
3459 | ||
3460 | for_each_subsys(root, ss) { | |
bd89aabc PM |
3461 | if (cgrp->subsys[ss->subsys_id]) |
3462 | ss->destroy(ss, cgrp); | |
ddbcc7e8 PM |
3463 | } |
3464 | ||
3465 | mutex_unlock(&cgroup_mutex); | |
3466 | ||
3467 | /* Release the reference count that we took on the superblock */ | |
3468 | deactivate_super(sb); | |
3469 | ||
bd89aabc | 3470 | kfree(cgrp); |
ddbcc7e8 PM |
3471 | return err; |
3472 | } | |
3473 | ||
3474 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
3475 | { | |
3476 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
3477 | ||
3478 | /* the vfs holds inode->i_mutex already */ | |
3479 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
3480 | } | |
3481 | ||
55b6fd01 | 3482 | static int cgroup_has_css_refs(struct cgroup *cgrp) |
81a6a5cd PM |
3483 | { |
3484 | /* Check the reference count on each subsystem. Since we | |
3485 | * already established that there are no tasks in the | |
e7c5ec91 | 3486 | * cgroup, if the css refcount is also 1, then there should |
81a6a5cd PM |
3487 | * be no outstanding references, so the subsystem is safe to |
3488 | * destroy. We scan across all subsystems rather than using | |
3489 | * the per-hierarchy linked list of mounted subsystems since | |
3490 | * we can be called via check_for_release() with no | |
3491 | * synchronization other than RCU, and the subsystem linked | |
3492 | * list isn't RCU-safe */ | |
3493 | int i; | |
aae8aab4 BB |
3494 | /* |
3495 | * We won't need to lock the subsys array, because the subsystems | |
3496 | * we're concerned about aren't going anywhere since our cgroup root | |
3497 | * has a reference on them. | |
3498 | */ | |
81a6a5cd PM |
3499 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3500 | struct cgroup_subsys *ss = subsys[i]; | |
3501 | struct cgroup_subsys_state *css; | |
aae8aab4 BB |
3502 | /* Skip subsystems not present or not in this hierarchy */ |
3503 | if (ss == NULL || ss->root != cgrp->root) | |
81a6a5cd | 3504 | continue; |
bd89aabc | 3505 | css = cgrp->subsys[ss->subsys_id]; |
81a6a5cd PM |
3506 | /* When called from check_for_release() it's possible |
3507 | * that by this point the cgroup has been removed | |
3508 | * and the css deleted. But a false-positive doesn't | |
3509 | * matter, since it can only happen if the cgroup | |
3510 | * has been deleted and hence no longer needs the | |
3511 | * release agent to be called anyway. */ | |
e7c5ec91 | 3512 | if (css && (atomic_read(&css->refcnt) > 1)) |
81a6a5cd | 3513 | return 1; |
81a6a5cd PM |
3514 | } |
3515 | return 0; | |
3516 | } | |
3517 | ||
e7c5ec91 PM |
3518 | /* |
3519 | * Atomically mark all (or else none) of the cgroup's CSS objects as | |
3520 | * CSS_REMOVED. Return true on success, or false if the cgroup has | |
3521 | * busy subsystems. Call with cgroup_mutex held | |
3522 | */ | |
3523 | ||
3524 | static int cgroup_clear_css_refs(struct cgroup *cgrp) | |
3525 | { | |
3526 | struct cgroup_subsys *ss; | |
3527 | unsigned long flags; | |
3528 | bool failed = false; | |
3529 | local_irq_save(flags); | |
3530 | for_each_subsys(cgrp->root, ss) { | |
3531 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3532 | int refcnt; | |
804b3c28 | 3533 | while (1) { |
e7c5ec91 PM |
3534 | /* We can only remove a CSS with a refcnt==1 */ |
3535 | refcnt = atomic_read(&css->refcnt); | |
3536 | if (refcnt > 1) { | |
3537 | failed = true; | |
3538 | goto done; | |
3539 | } | |
3540 | BUG_ON(!refcnt); | |
3541 | /* | |
3542 | * Drop the refcnt to 0 while we check other | |
3543 | * subsystems. This will cause any racing | |
3544 | * css_tryget() to spin until we set the | |
3545 | * CSS_REMOVED bits or abort | |
3546 | */ | |
804b3c28 PM |
3547 | if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt) |
3548 | break; | |
3549 | cpu_relax(); | |
3550 | } | |
e7c5ec91 PM |
3551 | } |
3552 | done: | |
3553 | for_each_subsys(cgrp->root, ss) { | |
3554 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3555 | if (failed) { | |
3556 | /* | |
3557 | * Restore old refcnt if we previously managed | |
3558 | * to clear it from 1 to 0 | |
3559 | */ | |
3560 | if (!atomic_read(&css->refcnt)) | |
3561 | atomic_set(&css->refcnt, 1); | |
3562 | } else { | |
3563 | /* Commit the fact that the CSS is removed */ | |
3564 | set_bit(CSS_REMOVED, &css->flags); | |
3565 | } | |
3566 | } | |
3567 | local_irq_restore(flags); | |
3568 | return !failed; | |
3569 | } | |
3570 | ||
ddbcc7e8 PM |
3571 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
3572 | { | |
bd89aabc | 3573 | struct cgroup *cgrp = dentry->d_fsdata; |
ddbcc7e8 PM |
3574 | struct dentry *d; |
3575 | struct cgroup *parent; | |
ec64f515 | 3576 | DEFINE_WAIT(wait); |
4ab78683 | 3577 | struct cgroup_event *event, *tmp; |
ec64f515 | 3578 | int ret; |
ddbcc7e8 PM |
3579 | |
3580 | /* the vfs holds both inode->i_mutex already */ | |
ec64f515 | 3581 | again: |
ddbcc7e8 | 3582 | mutex_lock(&cgroup_mutex); |
bd89aabc | 3583 | if (atomic_read(&cgrp->count) != 0) { |
ddbcc7e8 PM |
3584 | mutex_unlock(&cgroup_mutex); |
3585 | return -EBUSY; | |
3586 | } | |
bd89aabc | 3587 | if (!list_empty(&cgrp->children)) { |
ddbcc7e8 PM |
3588 | mutex_unlock(&cgroup_mutex); |
3589 | return -EBUSY; | |
3590 | } | |
3fa59dfb | 3591 | mutex_unlock(&cgroup_mutex); |
a043e3b2 | 3592 | |
88703267 KH |
3593 | /* |
3594 | * In general, subsystem has no css->refcnt after pre_destroy(). But | |
3595 | * in racy cases, subsystem may have to get css->refcnt after | |
3596 | * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes | |
3597 | * make rmdir return -EBUSY too often. To avoid that, we use waitqueue | |
3598 | * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir | |
3599 | * and subsystem's reference count handling. Please see css_get/put | |
3600 | * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation. | |
3601 | */ | |
3602 | set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
3603 | ||
4fca88c8 | 3604 | /* |
a043e3b2 LZ |
3605 | * Call pre_destroy handlers of subsys. Notify subsystems |
3606 | * that rmdir() request comes. | |
4fca88c8 | 3607 | */ |
ec64f515 | 3608 | ret = cgroup_call_pre_destroy(cgrp); |
88703267 KH |
3609 | if (ret) { |
3610 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
ec64f515 | 3611 | return ret; |
88703267 | 3612 | } |
ddbcc7e8 | 3613 | |
3fa59dfb KH |
3614 | mutex_lock(&cgroup_mutex); |
3615 | parent = cgrp->parent; | |
ec64f515 | 3616 | if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { |
88703267 | 3617 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
ddbcc7e8 PM |
3618 | mutex_unlock(&cgroup_mutex); |
3619 | return -EBUSY; | |
3620 | } | |
ec64f515 | 3621 | prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE); |
ec64f515 KH |
3622 | if (!cgroup_clear_css_refs(cgrp)) { |
3623 | mutex_unlock(&cgroup_mutex); | |
88703267 KH |
3624 | /* |
3625 | * Because someone may call cgroup_wakeup_rmdir_waiter() before | |
3626 | * prepare_to_wait(), we need to check this flag. | |
3627 | */ | |
3628 | if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)) | |
3629 | schedule(); | |
ec64f515 KH |
3630 | finish_wait(&cgroup_rmdir_waitq, &wait); |
3631 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
3632 | if (signal_pending(current)) | |
3633 | return -EINTR; | |
3634 | goto again; | |
3635 | } | |
3636 | /* NO css_tryget() can success after here. */ | |
3637 | finish_wait(&cgroup_rmdir_waitq, &wait); | |
3638 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); | |
ddbcc7e8 | 3639 | |
81a6a5cd | 3640 | spin_lock(&release_list_lock); |
bd89aabc PM |
3641 | set_bit(CGRP_REMOVED, &cgrp->flags); |
3642 | if (!list_empty(&cgrp->release_list)) | |
8d258797 | 3643 | list_del_init(&cgrp->release_list); |
81a6a5cd | 3644 | spin_unlock(&release_list_lock); |
999cd8a4 PM |
3645 | |
3646 | cgroup_lock_hierarchy(cgrp->root); | |
3647 | /* delete this cgroup from parent->children */ | |
8d258797 | 3648 | list_del_init(&cgrp->sibling); |
999cd8a4 PM |
3649 | cgroup_unlock_hierarchy(cgrp->root); |
3650 | ||
bd89aabc | 3651 | d = dget(cgrp->dentry); |
ddbcc7e8 PM |
3652 | |
3653 | cgroup_d_remove_dir(d); | |
3654 | dput(d); | |
ddbcc7e8 | 3655 | |
bd89aabc | 3656 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd PM |
3657 | check_for_release(parent); |
3658 | ||
4ab78683 KS |
3659 | /* |
3660 | * Unregister events and notify userspace. | |
3661 | * Notify userspace about cgroup removing only after rmdir of cgroup | |
3662 | * directory to avoid race between userspace and kernelspace | |
3663 | */ | |
3664 | spin_lock(&cgrp->event_list_lock); | |
3665 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { | |
3666 | list_del(&event->list); | |
3667 | remove_wait_queue(event->wqh, &event->wait); | |
3668 | eventfd_signal(event->eventfd, 1); | |
3669 | schedule_work(&event->remove); | |
3670 | } | |
3671 | spin_unlock(&cgrp->event_list_lock); | |
3672 | ||
ddbcc7e8 | 3673 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
3674 | return 0; |
3675 | } | |
3676 | ||
06a11920 | 3677 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 3678 | { |
ddbcc7e8 | 3679 | struct cgroup_subsys_state *css; |
cfe36bde DC |
3680 | |
3681 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 PM |
3682 | |
3683 | /* Create the top cgroup state for this subsystem */ | |
33a68ac1 | 3684 | list_add(&ss->sibling, &rootnode.subsys_list); |
ddbcc7e8 PM |
3685 | ss->root = &rootnode; |
3686 | css = ss->create(ss, dummytop); | |
3687 | /* We don't handle early failures gracefully */ | |
3688 | BUG_ON(IS_ERR(css)); | |
3689 | init_cgroup_css(css, ss, dummytop); | |
3690 | ||
e8d55fde | 3691 | /* Update the init_css_set to contain a subsys |
817929ec | 3692 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
3693 | * newly registered, all tasks and hence the |
3694 | * init_css_set is in the subsystem's top cgroup. */ | |
3695 | init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id]; | |
ddbcc7e8 PM |
3696 | |
3697 | need_forkexit_callback |= ss->fork || ss->exit; | |
3698 | ||
e8d55fde LZ |
3699 | /* At system boot, before all subsystems have been |
3700 | * registered, no tasks have been forked, so we don't | |
3701 | * need to invoke fork callbacks here. */ | |
3702 | BUG_ON(!list_empty(&init_task.tasks)); | |
3703 | ||
999cd8a4 | 3704 | mutex_init(&ss->hierarchy_mutex); |
cfebe563 | 3705 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); |
ddbcc7e8 | 3706 | ss->active = 1; |
e6a1105b BB |
3707 | |
3708 | /* this function shouldn't be used with modular subsystems, since they | |
3709 | * need to register a subsys_id, among other things */ | |
3710 | BUG_ON(ss->module); | |
3711 | } | |
3712 | ||
3713 | /** | |
3714 | * cgroup_load_subsys: load and register a modular subsystem at runtime | |
3715 | * @ss: the subsystem to load | |
3716 | * | |
3717 | * This function should be called in a modular subsystem's initcall. If the | |
88393161 | 3718 | * subsystem is built as a module, it will be assigned a new subsys_id and set |
e6a1105b BB |
3719 | * up for use. If the subsystem is built-in anyway, work is delegated to the |
3720 | * simpler cgroup_init_subsys. | |
3721 | */ | |
3722 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) | |
3723 | { | |
3724 | int i; | |
3725 | struct cgroup_subsys_state *css; | |
3726 | ||
3727 | /* check name and function validity */ | |
3728 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || | |
3729 | ss->create == NULL || ss->destroy == NULL) | |
3730 | return -EINVAL; | |
3731 | ||
3732 | /* | |
3733 | * we don't support callbacks in modular subsystems. this check is | |
3734 | * before the ss->module check for consistency; a subsystem that could | |
3735 | * be a module should still have no callbacks even if the user isn't | |
3736 | * compiling it as one. | |
3737 | */ | |
3738 | if (ss->fork || ss->exit) | |
3739 | return -EINVAL; | |
3740 | ||
3741 | /* | |
3742 | * an optionally modular subsystem is built-in: we want to do nothing, | |
3743 | * since cgroup_init_subsys will have already taken care of it. | |
3744 | */ | |
3745 | if (ss->module == NULL) { | |
3746 | /* a few sanity checks */ | |
3747 | BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); | |
3748 | BUG_ON(subsys[ss->subsys_id] != ss); | |
3749 | return 0; | |
3750 | } | |
3751 | ||
3752 | /* | |
3753 | * need to register a subsys id before anything else - for example, | |
3754 | * init_cgroup_css needs it. | |
3755 | */ | |
3756 | mutex_lock(&cgroup_mutex); | |
3757 | /* find the first empty slot in the array */ | |
3758 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { | |
3759 | if (subsys[i] == NULL) | |
3760 | break; | |
3761 | } | |
3762 | if (i == CGROUP_SUBSYS_COUNT) { | |
3763 | /* maximum number of subsystems already registered! */ | |
3764 | mutex_unlock(&cgroup_mutex); | |
3765 | return -EBUSY; | |
3766 | } | |
3767 | /* assign ourselves the subsys_id */ | |
3768 | ss->subsys_id = i; | |
3769 | subsys[i] = ss; | |
3770 | ||
3771 | /* | |
3772 | * no ss->create seems to need anything important in the ss struct, so | |
3773 | * this can happen first (i.e. before the rootnode attachment). | |
3774 | */ | |
3775 | css = ss->create(ss, dummytop); | |
3776 | if (IS_ERR(css)) { | |
3777 | /* failure case - need to deassign the subsys[] slot. */ | |
3778 | subsys[i] = NULL; | |
3779 | mutex_unlock(&cgroup_mutex); | |
3780 | return PTR_ERR(css); | |
3781 | } | |
3782 | ||
3783 | list_add(&ss->sibling, &rootnode.subsys_list); | |
3784 | ss->root = &rootnode; | |
3785 | ||
3786 | /* our new subsystem will be attached to the dummy hierarchy. */ | |
3787 | init_cgroup_css(css, ss, dummytop); | |
3788 | /* init_idr must be after init_cgroup_css because it sets css->id. */ | |
3789 | if (ss->use_id) { | |
3790 | int ret = cgroup_init_idr(ss, css); | |
3791 | if (ret) { | |
3792 | dummytop->subsys[ss->subsys_id] = NULL; | |
3793 | ss->destroy(ss, dummytop); | |
3794 | subsys[i] = NULL; | |
3795 | mutex_unlock(&cgroup_mutex); | |
3796 | return ret; | |
3797 | } | |
3798 | } | |
3799 | ||
3800 | /* | |
3801 | * Now we need to entangle the css into the existing css_sets. unlike | |
3802 | * in cgroup_init_subsys, there are now multiple css_sets, so each one | |
3803 | * will need a new pointer to it; done by iterating the css_set_table. | |
3804 | * furthermore, modifying the existing css_sets will corrupt the hash | |
3805 | * table state, so each changed css_set will need its hash recomputed. | |
3806 | * this is all done under the css_set_lock. | |
3807 | */ | |
3808 | write_lock(&css_set_lock); | |
3809 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { | |
3810 | struct css_set *cg; | |
3811 | struct hlist_node *node, *tmp; | |
3812 | struct hlist_head *bucket = &css_set_table[i], *new_bucket; | |
3813 | ||
3814 | hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { | |
3815 | /* skip entries that we already rehashed */ | |
3816 | if (cg->subsys[ss->subsys_id]) | |
3817 | continue; | |
3818 | /* remove existing entry */ | |
3819 | hlist_del(&cg->hlist); | |
3820 | /* set new value */ | |
3821 | cg->subsys[ss->subsys_id] = css; | |
3822 | /* recompute hash and restore entry */ | |
3823 | new_bucket = css_set_hash(cg->subsys); | |
3824 | hlist_add_head(&cg->hlist, new_bucket); | |
3825 | } | |
3826 | } | |
3827 | write_unlock(&css_set_lock); | |
3828 | ||
3829 | mutex_init(&ss->hierarchy_mutex); | |
3830 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); | |
3831 | ss->active = 1; | |
3832 | ||
e6a1105b BB |
3833 | /* success! */ |
3834 | mutex_unlock(&cgroup_mutex); | |
3835 | return 0; | |
ddbcc7e8 | 3836 | } |
e6a1105b | 3837 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
ddbcc7e8 | 3838 | |
cf5d5941 BB |
3839 | /** |
3840 | * cgroup_unload_subsys: unload a modular subsystem | |
3841 | * @ss: the subsystem to unload | |
3842 | * | |
3843 | * This function should be called in a modular subsystem's exitcall. When this | |
3844 | * function is invoked, the refcount on the subsystem's module will be 0, so | |
3845 | * the subsystem will not be attached to any hierarchy. | |
3846 | */ | |
3847 | void cgroup_unload_subsys(struct cgroup_subsys *ss) | |
3848 | { | |
3849 | struct cg_cgroup_link *link; | |
3850 | struct hlist_head *hhead; | |
3851 | ||
3852 | BUG_ON(ss->module == NULL); | |
3853 | ||
3854 | /* | |
3855 | * we shouldn't be called if the subsystem is in use, and the use of | |
3856 | * try_module_get in parse_cgroupfs_options should ensure that it | |
3857 | * doesn't start being used while we're killing it off. | |
3858 | */ | |
3859 | BUG_ON(ss->root != &rootnode); | |
3860 | ||
3861 | mutex_lock(&cgroup_mutex); | |
3862 | /* deassign the subsys_id */ | |
3863 | BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT); | |
3864 | subsys[ss->subsys_id] = NULL; | |
3865 | ||
3866 | /* remove subsystem from rootnode's list of subsystems */ | |
8d258797 | 3867 | list_del_init(&ss->sibling); |
cf5d5941 BB |
3868 | |
3869 | /* | |
3870 | * disentangle the css from all css_sets attached to the dummytop. as | |
3871 | * in loading, we need to pay our respects to the hashtable gods. | |
3872 | */ | |
3873 | write_lock(&css_set_lock); | |
3874 | list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { | |
3875 | struct css_set *cg = link->cg; | |
3876 | ||
3877 | hlist_del(&cg->hlist); | |
3878 | BUG_ON(!cg->subsys[ss->subsys_id]); | |
3879 | cg->subsys[ss->subsys_id] = NULL; | |
3880 | hhead = css_set_hash(cg->subsys); | |
3881 | hlist_add_head(&cg->hlist, hhead); | |
3882 | } | |
3883 | write_unlock(&css_set_lock); | |
3884 | ||
3885 | /* | |
3886 | * remove subsystem's css from the dummytop and free it - need to free | |
3887 | * before marking as null because ss->destroy needs the cgrp->subsys | |
3888 | * pointer to find their state. note that this also takes care of | |
3889 | * freeing the css_id. | |
3890 | */ | |
3891 | ss->destroy(ss, dummytop); | |
3892 | dummytop->subsys[ss->subsys_id] = NULL; | |
3893 | ||
3894 | mutex_unlock(&cgroup_mutex); | |
3895 | } | |
3896 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); | |
3897 | ||
ddbcc7e8 | 3898 | /** |
a043e3b2 LZ |
3899 | * cgroup_init_early - cgroup initialization at system boot |
3900 | * | |
3901 | * Initialize cgroups at system boot, and initialize any | |
3902 | * subsystems that request early init. | |
ddbcc7e8 PM |
3903 | */ |
3904 | int __init cgroup_init_early(void) | |
3905 | { | |
3906 | int i; | |
146aa1bd | 3907 | atomic_set(&init_css_set.refcount, 1); |
817929ec PM |
3908 | INIT_LIST_HEAD(&init_css_set.cg_links); |
3909 | INIT_LIST_HEAD(&init_css_set.tasks); | |
472b1053 | 3910 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 3911 | css_set_count = 1; |
ddbcc7e8 | 3912 | init_cgroup_root(&rootnode); |
817929ec PM |
3913 | root_count = 1; |
3914 | init_task.cgroups = &init_css_set; | |
3915 | ||
3916 | init_css_set_link.cg = &init_css_set; | |
7717f7ba | 3917 | init_css_set_link.cgrp = dummytop; |
bd89aabc | 3918 | list_add(&init_css_set_link.cgrp_link_list, |
817929ec PM |
3919 | &rootnode.top_cgroup.css_sets); |
3920 | list_add(&init_css_set_link.cg_link_list, | |
3921 | &init_css_set.cg_links); | |
ddbcc7e8 | 3922 | |
472b1053 LZ |
3923 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) |
3924 | INIT_HLIST_HEAD(&css_set_table[i]); | |
3925 | ||
aae8aab4 BB |
3926 | /* at bootup time, we don't worry about modular subsystems */ |
3927 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
ddbcc7e8 PM |
3928 | struct cgroup_subsys *ss = subsys[i]; |
3929 | ||
3930 | BUG_ON(!ss->name); | |
3931 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
3932 | BUG_ON(!ss->create); | |
3933 | BUG_ON(!ss->destroy); | |
3934 | if (ss->subsys_id != i) { | |
cfe36bde | 3935 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
ddbcc7e8 PM |
3936 | ss->name, ss->subsys_id); |
3937 | BUG(); | |
3938 | } | |
3939 | ||
3940 | if (ss->early_init) | |
3941 | cgroup_init_subsys(ss); | |
3942 | } | |
3943 | return 0; | |
3944 | } | |
3945 | ||
3946 | /** | |
a043e3b2 LZ |
3947 | * cgroup_init - cgroup initialization |
3948 | * | |
3949 | * Register cgroup filesystem and /proc file, and initialize | |
3950 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
3951 | */ |
3952 | int __init cgroup_init(void) | |
3953 | { | |
3954 | int err; | |
3955 | int i; | |
472b1053 | 3956 | struct hlist_head *hhead; |
a424316c PM |
3957 | |
3958 | err = bdi_init(&cgroup_backing_dev_info); | |
3959 | if (err) | |
3960 | return err; | |
ddbcc7e8 | 3961 | |
aae8aab4 BB |
3962 | /* at bootup time, we don't worry about modular subsystems */ |
3963 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
ddbcc7e8 PM |
3964 | struct cgroup_subsys *ss = subsys[i]; |
3965 | if (!ss->early_init) | |
3966 | cgroup_init_subsys(ss); | |
38460b48 | 3967 | if (ss->use_id) |
e6a1105b | 3968 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
ddbcc7e8 PM |
3969 | } |
3970 | ||
472b1053 LZ |
3971 | /* Add init_css_set to the hash table */ |
3972 | hhead = css_set_hash(init_css_set.subsys); | |
3973 | hlist_add_head(&init_css_set.hlist, hhead); | |
2c6ab6d2 | 3974 | BUG_ON(!init_root_id(&rootnode)); |
676db4af GK |
3975 | |
3976 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); | |
3977 | if (!cgroup_kobj) { | |
3978 | err = -ENOMEM; | |
3979 | goto out; | |
3980 | } | |
3981 | ||
ddbcc7e8 | 3982 | err = register_filesystem(&cgroup_fs_type); |
676db4af GK |
3983 | if (err < 0) { |
3984 | kobject_put(cgroup_kobj); | |
ddbcc7e8 | 3985 | goto out; |
676db4af | 3986 | } |
ddbcc7e8 | 3987 | |
46ae220b | 3988 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
a424316c | 3989 | |
ddbcc7e8 | 3990 | out: |
a424316c PM |
3991 | if (err) |
3992 | bdi_destroy(&cgroup_backing_dev_info); | |
3993 | ||
ddbcc7e8 PM |
3994 | return err; |
3995 | } | |
b4f48b63 | 3996 | |
a424316c PM |
3997 | /* |
3998 | * proc_cgroup_show() | |
3999 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4000 | * - Used for /proc/<pid>/cgroup. | |
4001 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
4002 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 4003 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
4004 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
4005 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
4006 | * cgroup to top_cgroup. | |
4007 | */ | |
4008 | ||
4009 | /* TODO: Use a proper seq_file iterator */ | |
4010 | static int proc_cgroup_show(struct seq_file *m, void *v) | |
4011 | { | |
4012 | struct pid *pid; | |
4013 | struct task_struct *tsk; | |
4014 | char *buf; | |
4015 | int retval; | |
4016 | struct cgroupfs_root *root; | |
4017 | ||
4018 | retval = -ENOMEM; | |
4019 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
4020 | if (!buf) | |
4021 | goto out; | |
4022 | ||
4023 | retval = -ESRCH; | |
4024 | pid = m->private; | |
4025 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4026 | if (!tsk) | |
4027 | goto out_free; | |
4028 | ||
4029 | retval = 0; | |
4030 | ||
4031 | mutex_lock(&cgroup_mutex); | |
4032 | ||
e5f6a860 | 4033 | for_each_active_root(root) { |
a424316c | 4034 | struct cgroup_subsys *ss; |
bd89aabc | 4035 | struct cgroup *cgrp; |
a424316c PM |
4036 | int count = 0; |
4037 | ||
2c6ab6d2 | 4038 | seq_printf(m, "%d:", root->hierarchy_id); |
a424316c PM |
4039 | for_each_subsys(root, ss) |
4040 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
c6d57f33 PM |
4041 | if (strlen(root->name)) |
4042 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4043 | root->name); | |
a424316c | 4044 | seq_putc(m, ':'); |
7717f7ba | 4045 | cgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 4046 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
a424316c PM |
4047 | if (retval < 0) |
4048 | goto out_unlock; | |
4049 | seq_puts(m, buf); | |
4050 | seq_putc(m, '\n'); | |
4051 | } | |
4052 | ||
4053 | out_unlock: | |
4054 | mutex_unlock(&cgroup_mutex); | |
4055 | put_task_struct(tsk); | |
4056 | out_free: | |
4057 | kfree(buf); | |
4058 | out: | |
4059 | return retval; | |
4060 | } | |
4061 | ||
4062 | static int cgroup_open(struct inode *inode, struct file *file) | |
4063 | { | |
4064 | struct pid *pid = PROC_I(inode)->pid; | |
4065 | return single_open(file, proc_cgroup_show, pid); | |
4066 | } | |
4067 | ||
828c0950 | 4068 | const struct file_operations proc_cgroup_operations = { |
a424316c PM |
4069 | .open = cgroup_open, |
4070 | .read = seq_read, | |
4071 | .llseek = seq_lseek, | |
4072 | .release = single_release, | |
4073 | }; | |
4074 | ||
4075 | /* Display information about each subsystem and each hierarchy */ | |
4076 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4077 | { | |
4078 | int i; | |
a424316c | 4079 | |
8bab8dde | 4080 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4081 | /* |
4082 | * ideally we don't want subsystems moving around while we do this. | |
4083 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4084 | * subsys/hierarchy state. | |
4085 | */ | |
a424316c | 4086 | mutex_lock(&cgroup_mutex); |
a424316c PM |
4087 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
4088 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
4089 | if (ss == NULL) |
4090 | continue; | |
2c6ab6d2 PM |
4091 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4092 | ss->name, ss->root->hierarchy_id, | |
8bab8dde | 4093 | ss->root->number_of_cgroups, !ss->disabled); |
a424316c PM |
4094 | } |
4095 | mutex_unlock(&cgroup_mutex); | |
4096 | return 0; | |
4097 | } | |
4098 | ||
4099 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4100 | { | |
9dce07f1 | 4101 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
4102 | } |
4103 | ||
828c0950 | 4104 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
4105 | .open = cgroupstats_open, |
4106 | .read = seq_read, | |
4107 | .llseek = seq_lseek, | |
4108 | .release = single_release, | |
4109 | }; | |
4110 | ||
b4f48b63 PM |
4111 | /** |
4112 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
a043e3b2 | 4113 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 PM |
4114 | * |
4115 | * Description: A task inherits its parent's cgroup at fork(). | |
4116 | * | |
4117 | * A pointer to the shared css_set was automatically copied in | |
4118 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
4119 | * it was not made under the protection of RCU or cgroup_mutex, so | |
956db3ca | 4120 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might |
817929ec PM |
4121 | * have already changed current->cgroups, allowing the previously |
4122 | * referenced cgroup group to be removed and freed. | |
b4f48b63 PM |
4123 | * |
4124 | * At the point that cgroup_fork() is called, 'current' is the parent | |
4125 | * task, and the passed argument 'child' points to the child task. | |
4126 | */ | |
4127 | void cgroup_fork(struct task_struct *child) | |
4128 | { | |
817929ec PM |
4129 | task_lock(current); |
4130 | child->cgroups = current->cgroups; | |
4131 | get_css_set(child->cgroups); | |
4132 | task_unlock(current); | |
4133 | INIT_LIST_HEAD(&child->cg_list); | |
b4f48b63 PM |
4134 | } |
4135 | ||
4136 | /** | |
a043e3b2 LZ |
4137 | * cgroup_fork_callbacks - run fork callbacks |
4138 | * @child: the new task | |
4139 | * | |
4140 | * Called on a new task very soon before adding it to the | |
4141 | * tasklist. No need to take any locks since no-one can | |
4142 | * be operating on this task. | |
b4f48b63 PM |
4143 | */ |
4144 | void cgroup_fork_callbacks(struct task_struct *child) | |
4145 | { | |
4146 | if (need_forkexit_callback) { | |
4147 | int i; | |
aae8aab4 BB |
4148 | /* |
4149 | * forkexit callbacks are only supported for builtin | |
4150 | * subsystems, and the builtin section of the subsys array is | |
4151 | * immutable, so we don't need to lock the subsys array here. | |
4152 | */ | |
4153 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
b4f48b63 PM |
4154 | struct cgroup_subsys *ss = subsys[i]; |
4155 | if (ss->fork) | |
4156 | ss->fork(ss, child); | |
4157 | } | |
4158 | } | |
4159 | } | |
4160 | ||
817929ec | 4161 | /** |
a043e3b2 LZ |
4162 | * cgroup_post_fork - called on a new task after adding it to the task list |
4163 | * @child: the task in question | |
4164 | * | |
4165 | * Adds the task to the list running through its css_set if necessary. | |
4166 | * Has to be after the task is visible on the task list in case we race | |
4167 | * with the first call to cgroup_iter_start() - to guarantee that the | |
4168 | * new task ends up on its list. | |
4169 | */ | |
817929ec PM |
4170 | void cgroup_post_fork(struct task_struct *child) |
4171 | { | |
4172 | if (use_task_css_set_links) { | |
4173 | write_lock(&css_set_lock); | |
b12b533f | 4174 | task_lock(child); |
817929ec PM |
4175 | if (list_empty(&child->cg_list)) |
4176 | list_add(&child->cg_list, &child->cgroups->tasks); | |
b12b533f | 4177 | task_unlock(child); |
817929ec PM |
4178 | write_unlock(&css_set_lock); |
4179 | } | |
4180 | } | |
b4f48b63 PM |
4181 | /** |
4182 | * cgroup_exit - detach cgroup from exiting task | |
4183 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 4184 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
4185 | * |
4186 | * Description: Detach cgroup from @tsk and release it. | |
4187 | * | |
4188 | * Note that cgroups marked notify_on_release force every task in | |
4189 | * them to take the global cgroup_mutex mutex when exiting. | |
4190 | * This could impact scaling on very large systems. Be reluctant to | |
4191 | * use notify_on_release cgroups where very high task exit scaling | |
4192 | * is required on large systems. | |
4193 | * | |
4194 | * the_top_cgroup_hack: | |
4195 | * | |
4196 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
4197 | * | |
4198 | * We call cgroup_exit() while the task is still competent to | |
4199 | * handle notify_on_release(), then leave the task attached to the | |
4200 | * root cgroup in each hierarchy for the remainder of its exit. | |
4201 | * | |
4202 | * To do this properly, we would increment the reference count on | |
4203 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
4204 | * code we would add a second cgroup function call, to drop that | |
4205 | * reference. This would just create an unnecessary hot spot on | |
4206 | * the top_cgroup reference count, to no avail. | |
4207 | * | |
4208 | * Normally, holding a reference to a cgroup without bumping its | |
4209 | * count is unsafe. The cgroup could go away, or someone could | |
4210 | * attach us to a different cgroup, decrementing the count on | |
4211 | * the first cgroup that we never incremented. But in this case, | |
4212 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
4213 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
4214 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
4215 | */ |
4216 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
4217 | { | |
817929ec | 4218 | struct css_set *cg; |
d41d5a01 | 4219 | int i; |
817929ec PM |
4220 | |
4221 | /* | |
4222 | * Unlink from the css_set task list if necessary. | |
4223 | * Optimistically check cg_list before taking | |
4224 | * css_set_lock | |
4225 | */ | |
4226 | if (!list_empty(&tsk->cg_list)) { | |
4227 | write_lock(&css_set_lock); | |
4228 | if (!list_empty(&tsk->cg_list)) | |
8d258797 | 4229 | list_del_init(&tsk->cg_list); |
817929ec PM |
4230 | write_unlock(&css_set_lock); |
4231 | } | |
4232 | ||
b4f48b63 PM |
4233 | /* Reassign the task to the init_css_set. */ |
4234 | task_lock(tsk); | |
817929ec PM |
4235 | cg = tsk->cgroups; |
4236 | tsk->cgroups = &init_css_set; | |
d41d5a01 PZ |
4237 | |
4238 | if (run_callbacks && need_forkexit_callback) { | |
4239 | /* | |
4240 | * modular subsystems can't use callbacks, so no need to lock | |
4241 | * the subsys array | |
4242 | */ | |
4243 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
4244 | struct cgroup_subsys *ss = subsys[i]; | |
4245 | if (ss->exit) { | |
4246 | struct cgroup *old_cgrp = | |
4247 | rcu_dereference_raw(cg->subsys[i])->cgroup; | |
4248 | struct cgroup *cgrp = task_cgroup(tsk, i); | |
4249 | ss->exit(ss, cgrp, old_cgrp, tsk); | |
4250 | } | |
4251 | } | |
4252 | } | |
b4f48b63 | 4253 | task_unlock(tsk); |
d41d5a01 | 4254 | |
817929ec | 4255 | if (cg) |
81a6a5cd | 4256 | put_css_set_taskexit(cg); |
b4f48b63 | 4257 | } |
697f4161 PM |
4258 | |
4259 | /** | |
a043e3b2 LZ |
4260 | * cgroup_clone - clone the cgroup the given subsystem is attached to |
4261 | * @tsk: the task to be moved | |
4262 | * @subsys: the given subsystem | |
e885dcde | 4263 | * @nodename: the name for the new cgroup |
a043e3b2 LZ |
4264 | * |
4265 | * Duplicate the current cgroup in the hierarchy that the given | |
4266 | * subsystem is attached to, and move this task into the new | |
4267 | * child. | |
697f4161 | 4268 | */ |
e885dcde SH |
4269 | int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, |
4270 | char *nodename) | |
697f4161 PM |
4271 | { |
4272 | struct dentry *dentry; | |
4273 | int ret = 0; | |
697f4161 PM |
4274 | struct cgroup *parent, *child; |
4275 | struct inode *inode; | |
4276 | struct css_set *cg; | |
4277 | struct cgroupfs_root *root; | |
4278 | struct cgroup_subsys *ss; | |
4279 | ||
4280 | /* We shouldn't be called by an unregistered subsystem */ | |
4281 | BUG_ON(!subsys->active); | |
4282 | ||
4283 | /* First figure out what hierarchy and cgroup we're dealing | |
4284 | * with, and pin them so we can drop cgroup_mutex */ | |
4285 | mutex_lock(&cgroup_mutex); | |
4286 | again: | |
4287 | root = subsys->root; | |
4288 | if (root == &rootnode) { | |
697f4161 PM |
4289 | mutex_unlock(&cgroup_mutex); |
4290 | return 0; | |
4291 | } | |
697f4161 | 4292 | |
697f4161 | 4293 | /* Pin the hierarchy */ |
1404f065 | 4294 | if (!atomic_inc_not_zero(&root->sb->s_active)) { |
7b574b7b LZ |
4295 | /* We race with the final deactivate_super() */ |
4296 | mutex_unlock(&cgroup_mutex); | |
4297 | return 0; | |
4298 | } | |
697f4161 | 4299 | |
817929ec | 4300 | /* Keep the cgroup alive */ |
1404f065 LZ |
4301 | task_lock(tsk); |
4302 | parent = task_cgroup(tsk, subsys->subsys_id); | |
4303 | cg = tsk->cgroups; | |
817929ec | 4304 | get_css_set(cg); |
104cbd55 | 4305 | task_unlock(tsk); |
1404f065 | 4306 | |
697f4161 PM |
4307 | mutex_unlock(&cgroup_mutex); |
4308 | ||
4309 | /* Now do the VFS work to create a cgroup */ | |
4310 | inode = parent->dentry->d_inode; | |
4311 | ||
4312 | /* Hold the parent directory mutex across this operation to | |
4313 | * stop anyone else deleting the new cgroup */ | |
4314 | mutex_lock(&inode->i_mutex); | |
4315 | dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename)); | |
4316 | if (IS_ERR(dentry)) { | |
4317 | printk(KERN_INFO | |
cfe36bde | 4318 | "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename, |
697f4161 PM |
4319 | PTR_ERR(dentry)); |
4320 | ret = PTR_ERR(dentry); | |
4321 | goto out_release; | |
4322 | } | |
4323 | ||
4324 | /* Create the cgroup directory, which also creates the cgroup */ | |
75139b82 | 4325 | ret = vfs_mkdir(inode, dentry, 0755); |
bd89aabc | 4326 | child = __d_cgrp(dentry); |
697f4161 PM |
4327 | dput(dentry); |
4328 | if (ret) { | |
4329 | printk(KERN_INFO | |
4330 | "Failed to create cgroup %s: %d\n", nodename, | |
4331 | ret); | |
4332 | goto out_release; | |
4333 | } | |
4334 | ||
697f4161 PM |
4335 | /* The cgroup now exists. Retake cgroup_mutex and check |
4336 | * that we're still in the same state that we thought we | |
4337 | * were. */ | |
4338 | mutex_lock(&cgroup_mutex); | |
4339 | if ((root != subsys->root) || | |
4340 | (parent != task_cgroup(tsk, subsys->subsys_id))) { | |
4341 | /* Aargh, we raced ... */ | |
4342 | mutex_unlock(&inode->i_mutex); | |
817929ec | 4343 | put_css_set(cg); |
697f4161 | 4344 | |
1404f065 | 4345 | deactivate_super(root->sb); |
697f4161 PM |
4346 | /* The cgroup is still accessible in the VFS, but |
4347 | * we're not going to try to rmdir() it at this | |
4348 | * point. */ | |
4349 | printk(KERN_INFO | |
4350 | "Race in cgroup_clone() - leaking cgroup %s\n", | |
4351 | nodename); | |
4352 | goto again; | |
4353 | } | |
4354 | ||
4355 | /* do any required auto-setup */ | |
4356 | for_each_subsys(root, ss) { | |
4357 | if (ss->post_clone) | |
4358 | ss->post_clone(ss, child); | |
4359 | } | |
4360 | ||
4361 | /* All seems fine. Finish by moving the task into the new cgroup */ | |
956db3ca | 4362 | ret = cgroup_attach_task(child, tsk); |
697f4161 PM |
4363 | mutex_unlock(&cgroup_mutex); |
4364 | ||
4365 | out_release: | |
4366 | mutex_unlock(&inode->i_mutex); | |
81a6a5cd PM |
4367 | |
4368 | mutex_lock(&cgroup_mutex); | |
817929ec | 4369 | put_css_set(cg); |
81a6a5cd | 4370 | mutex_unlock(&cgroup_mutex); |
1404f065 | 4371 | deactivate_super(root->sb); |
697f4161 PM |
4372 | return ret; |
4373 | } | |
4374 | ||
a043e3b2 | 4375 | /** |
313e924c | 4376 | * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp |
a043e3b2 | 4377 | * @cgrp: the cgroup in question |
313e924c | 4378 | * @task: the task in question |
a043e3b2 | 4379 | * |
313e924c GN |
4380 | * See if @cgrp is a descendant of @task's cgroup in the appropriate |
4381 | * hierarchy. | |
697f4161 PM |
4382 | * |
4383 | * If we are sending in dummytop, then presumably we are creating | |
4384 | * the top cgroup in the subsystem. | |
4385 | * | |
4386 | * Called only by the ns (nsproxy) cgroup. | |
4387 | */ | |
313e924c | 4388 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) |
697f4161 PM |
4389 | { |
4390 | int ret; | |
4391 | struct cgroup *target; | |
697f4161 | 4392 | |
bd89aabc | 4393 | if (cgrp == dummytop) |
697f4161 PM |
4394 | return 1; |
4395 | ||
7717f7ba | 4396 | target = task_cgroup_from_root(task, cgrp->root); |
bd89aabc PM |
4397 | while (cgrp != target && cgrp!= cgrp->top_cgroup) |
4398 | cgrp = cgrp->parent; | |
4399 | ret = (cgrp == target); | |
697f4161 PM |
4400 | return ret; |
4401 | } | |
81a6a5cd | 4402 | |
bd89aabc | 4403 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd PM |
4404 | { |
4405 | /* All of these checks rely on RCU to keep the cgroup | |
4406 | * structure alive */ | |
bd89aabc PM |
4407 | if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) |
4408 | && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { | |
81a6a5cd PM |
4409 | /* Control Group is currently removeable. If it's not |
4410 | * already queued for a userspace notification, queue | |
4411 | * it now */ | |
4412 | int need_schedule_work = 0; | |
4413 | spin_lock(&release_list_lock); | |
bd89aabc PM |
4414 | if (!cgroup_is_removed(cgrp) && |
4415 | list_empty(&cgrp->release_list)) { | |
4416 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
4417 | need_schedule_work = 1; |
4418 | } | |
4419 | spin_unlock(&release_list_lock); | |
4420 | if (need_schedule_work) | |
4421 | schedule_work(&release_agent_work); | |
4422 | } | |
4423 | } | |
4424 | ||
d7b9fff7 DN |
4425 | /* Caller must verify that the css is not for root cgroup */ |
4426 | void __css_put(struct cgroup_subsys_state *css, int count) | |
81a6a5cd | 4427 | { |
bd89aabc | 4428 | struct cgroup *cgrp = css->cgroup; |
3dece834 | 4429 | int val; |
81a6a5cd | 4430 | rcu_read_lock(); |
d7b9fff7 | 4431 | val = atomic_sub_return(count, &css->refcnt); |
3dece834 | 4432 | if (val == 1) { |
ec64f515 KH |
4433 | if (notify_on_release(cgrp)) { |
4434 | set_bit(CGRP_RELEASABLE, &cgrp->flags); | |
4435 | check_for_release(cgrp); | |
4436 | } | |
88703267 | 4437 | cgroup_wakeup_rmdir_waiter(cgrp); |
81a6a5cd PM |
4438 | } |
4439 | rcu_read_unlock(); | |
3dece834 | 4440 | WARN_ON_ONCE(val < 1); |
81a6a5cd | 4441 | } |
67523c48 | 4442 | EXPORT_SYMBOL_GPL(__css_put); |
81a6a5cd PM |
4443 | |
4444 | /* | |
4445 | * Notify userspace when a cgroup is released, by running the | |
4446 | * configured release agent with the name of the cgroup (path | |
4447 | * relative to the root of cgroup file system) as the argument. | |
4448 | * | |
4449 | * Most likely, this user command will try to rmdir this cgroup. | |
4450 | * | |
4451 | * This races with the possibility that some other task will be | |
4452 | * attached to this cgroup before it is removed, or that some other | |
4453 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
4454 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
4455 | * unused, and this cgroup will be reprieved from its death sentence, | |
4456 | * to continue to serve a useful existence. Next time it's released, | |
4457 | * we will get notified again, if it still has 'notify_on_release' set. | |
4458 | * | |
4459 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
4460 | * means only wait until the task is successfully execve()'d. The | |
4461 | * separate release agent task is forked by call_usermodehelper(), | |
4462 | * then control in this thread returns here, without waiting for the | |
4463 | * release agent task. We don't bother to wait because the caller of | |
4464 | * this routine has no use for the exit status of the release agent | |
4465 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 4466 | */ |
81a6a5cd PM |
4467 | static void cgroup_release_agent(struct work_struct *work) |
4468 | { | |
4469 | BUG_ON(work != &release_agent_work); | |
4470 | mutex_lock(&cgroup_mutex); | |
4471 | spin_lock(&release_list_lock); | |
4472 | while (!list_empty(&release_list)) { | |
4473 | char *argv[3], *envp[3]; | |
4474 | int i; | |
e788e066 | 4475 | char *pathbuf = NULL, *agentbuf = NULL; |
bd89aabc | 4476 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
4477 | struct cgroup, |
4478 | release_list); | |
bd89aabc | 4479 | list_del_init(&cgrp->release_list); |
81a6a5cd PM |
4480 | spin_unlock(&release_list_lock); |
4481 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
e788e066 PM |
4482 | if (!pathbuf) |
4483 | goto continue_free; | |
4484 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
4485 | goto continue_free; | |
4486 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
4487 | if (!agentbuf) | |
4488 | goto continue_free; | |
81a6a5cd PM |
4489 | |
4490 | i = 0; | |
e788e066 PM |
4491 | argv[i++] = agentbuf; |
4492 | argv[i++] = pathbuf; | |
81a6a5cd PM |
4493 | argv[i] = NULL; |
4494 | ||
4495 | i = 0; | |
4496 | /* minimal command environment */ | |
4497 | envp[i++] = "HOME=/"; | |
4498 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
4499 | envp[i] = NULL; | |
4500 | ||
4501 | /* Drop the lock while we invoke the usermode helper, | |
4502 | * since the exec could involve hitting disk and hence | |
4503 | * be a slow process */ | |
4504 | mutex_unlock(&cgroup_mutex); | |
4505 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 4506 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
4507 | continue_free: |
4508 | kfree(pathbuf); | |
4509 | kfree(agentbuf); | |
81a6a5cd PM |
4510 | spin_lock(&release_list_lock); |
4511 | } | |
4512 | spin_unlock(&release_list_lock); | |
4513 | mutex_unlock(&cgroup_mutex); | |
4514 | } | |
8bab8dde PM |
4515 | |
4516 | static int __init cgroup_disable(char *str) | |
4517 | { | |
4518 | int i; | |
4519 | char *token; | |
4520 | ||
4521 | while ((token = strsep(&str, ",")) != NULL) { | |
4522 | if (!*token) | |
4523 | continue; | |
aae8aab4 BB |
4524 | /* |
4525 | * cgroup_disable, being at boot time, can't know about module | |
4526 | * subsystems, so we don't worry about them. | |
4527 | */ | |
4528 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
8bab8dde PM |
4529 | struct cgroup_subsys *ss = subsys[i]; |
4530 | ||
4531 | if (!strcmp(token, ss->name)) { | |
4532 | ss->disabled = 1; | |
4533 | printk(KERN_INFO "Disabling %s control group" | |
4534 | " subsystem\n", ss->name); | |
4535 | break; | |
4536 | } | |
4537 | } | |
4538 | } | |
4539 | return 1; | |
4540 | } | |
4541 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 KH |
4542 | |
4543 | /* | |
4544 | * Functons for CSS ID. | |
4545 | */ | |
4546 | ||
4547 | /* | |
4548 | *To get ID other than 0, this should be called when !cgroup_is_removed(). | |
4549 | */ | |
4550 | unsigned short css_id(struct cgroup_subsys_state *css) | |
4551 | { | |
7f0f1546 KH |
4552 | struct css_id *cssid; |
4553 | ||
4554 | /* | |
4555 | * This css_id() can return correct value when somone has refcnt | |
4556 | * on this or this is under rcu_read_lock(). Once css->id is allocated, | |
4557 | * it's unchanged until freed. | |
4558 | */ | |
4559 | cssid = rcu_dereference_check(css->id, | |
4560 | rcu_read_lock_held() || atomic_read(&css->refcnt)); | |
38460b48 KH |
4561 | |
4562 | if (cssid) | |
4563 | return cssid->id; | |
4564 | return 0; | |
4565 | } | |
67523c48 | 4566 | EXPORT_SYMBOL_GPL(css_id); |
38460b48 KH |
4567 | |
4568 | unsigned short css_depth(struct cgroup_subsys_state *css) | |
4569 | { | |
7f0f1546 KH |
4570 | struct css_id *cssid; |
4571 | ||
4572 | cssid = rcu_dereference_check(css->id, | |
4573 | rcu_read_lock_held() || atomic_read(&css->refcnt)); | |
38460b48 KH |
4574 | |
4575 | if (cssid) | |
4576 | return cssid->depth; | |
4577 | return 0; | |
4578 | } | |
67523c48 | 4579 | EXPORT_SYMBOL_GPL(css_depth); |
38460b48 | 4580 | |
747388d7 KH |
4581 | /** |
4582 | * css_is_ancestor - test "root" css is an ancestor of "child" | |
4583 | * @child: the css to be tested. | |
4584 | * @root: the css supporsed to be an ancestor of the child. | |
4585 | * | |
4586 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because | |
4587 | * this function reads css->id, this use rcu_dereference() and rcu_read_lock(). | |
4588 | * But, considering usual usage, the csses should be valid objects after test. | |
4589 | * Assuming that the caller will do some action to the child if this returns | |
4590 | * returns true, the caller must take "child";s reference count. | |
4591 | * If "child" is valid object and this returns true, "root" is valid, too. | |
4592 | */ | |
4593 | ||
38460b48 | 4594 | bool css_is_ancestor(struct cgroup_subsys_state *child, |
0b7f569e | 4595 | const struct cgroup_subsys_state *root) |
38460b48 | 4596 | { |
747388d7 KH |
4597 | struct css_id *child_id; |
4598 | struct css_id *root_id; | |
4599 | bool ret = true; | |
38460b48 | 4600 | |
747388d7 KH |
4601 | rcu_read_lock(); |
4602 | child_id = rcu_dereference(child->id); | |
4603 | root_id = rcu_dereference(root->id); | |
4604 | if (!child_id | |
4605 | || !root_id | |
4606 | || (child_id->depth < root_id->depth) | |
4607 | || (child_id->stack[root_id->depth] != root_id->id)) | |
4608 | ret = false; | |
4609 | rcu_read_unlock(); | |
4610 | return ret; | |
38460b48 KH |
4611 | } |
4612 | ||
38460b48 KH |
4613 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
4614 | { | |
4615 | struct css_id *id = css->id; | |
4616 | /* When this is called before css_id initialization, id can be NULL */ | |
4617 | if (!id) | |
4618 | return; | |
4619 | ||
4620 | BUG_ON(!ss->use_id); | |
4621 | ||
4622 | rcu_assign_pointer(id->css, NULL); | |
4623 | rcu_assign_pointer(css->id, NULL); | |
4624 | spin_lock(&ss->id_lock); | |
4625 | idr_remove(&ss->idr, id->id); | |
4626 | spin_unlock(&ss->id_lock); | |
025cea99 | 4627 | kfree_rcu(id, rcu_head); |
38460b48 | 4628 | } |
67523c48 | 4629 | EXPORT_SYMBOL_GPL(free_css_id); |
38460b48 KH |
4630 | |
4631 | /* | |
4632 | * This is called by init or create(). Then, calls to this function are | |
4633 | * always serialized (By cgroup_mutex() at create()). | |
4634 | */ | |
4635 | ||
4636 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
4637 | { | |
4638 | struct css_id *newid; | |
4639 | int myid, error, size; | |
4640 | ||
4641 | BUG_ON(!ss->use_id); | |
4642 | ||
4643 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
4644 | newid = kzalloc(size, GFP_KERNEL); | |
4645 | if (!newid) | |
4646 | return ERR_PTR(-ENOMEM); | |
4647 | /* get id */ | |
4648 | if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) { | |
4649 | error = -ENOMEM; | |
4650 | goto err_out; | |
4651 | } | |
4652 | spin_lock(&ss->id_lock); | |
4653 | /* Don't use 0. allocates an ID of 1-65535 */ | |
4654 | error = idr_get_new_above(&ss->idr, newid, 1, &myid); | |
4655 | spin_unlock(&ss->id_lock); | |
4656 | ||
4657 | /* Returns error when there are no free spaces for new ID.*/ | |
4658 | if (error) { | |
4659 | error = -ENOSPC; | |
4660 | goto err_out; | |
4661 | } | |
4662 | if (myid > CSS_ID_MAX) | |
4663 | goto remove_idr; | |
4664 | ||
4665 | newid->id = myid; | |
4666 | newid->depth = depth; | |
4667 | return newid; | |
4668 | remove_idr: | |
4669 | error = -ENOSPC; | |
4670 | spin_lock(&ss->id_lock); | |
4671 | idr_remove(&ss->idr, myid); | |
4672 | spin_unlock(&ss->id_lock); | |
4673 | err_out: | |
4674 | kfree(newid); | |
4675 | return ERR_PTR(error); | |
4676 | ||
4677 | } | |
4678 | ||
e6a1105b BB |
4679 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
4680 | struct cgroup_subsys_state *rootcss) | |
38460b48 KH |
4681 | { |
4682 | struct css_id *newid; | |
38460b48 KH |
4683 | |
4684 | spin_lock_init(&ss->id_lock); | |
4685 | idr_init(&ss->idr); | |
4686 | ||
38460b48 KH |
4687 | newid = get_new_cssid(ss, 0); |
4688 | if (IS_ERR(newid)) | |
4689 | return PTR_ERR(newid); | |
4690 | ||
4691 | newid->stack[0] = newid->id; | |
4692 | newid->css = rootcss; | |
4693 | rootcss->id = newid; | |
4694 | return 0; | |
4695 | } | |
4696 | ||
4697 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
4698 | struct cgroup *child) | |
4699 | { | |
4700 | int subsys_id, i, depth = 0; | |
4701 | struct cgroup_subsys_state *parent_css, *child_css; | |
fae9c791 | 4702 | struct css_id *child_id, *parent_id; |
38460b48 KH |
4703 | |
4704 | subsys_id = ss->subsys_id; | |
4705 | parent_css = parent->subsys[subsys_id]; | |
4706 | child_css = child->subsys[subsys_id]; | |
38460b48 | 4707 | parent_id = parent_css->id; |
94b3dd0f | 4708 | depth = parent_id->depth + 1; |
38460b48 KH |
4709 | |
4710 | child_id = get_new_cssid(ss, depth); | |
4711 | if (IS_ERR(child_id)) | |
4712 | return PTR_ERR(child_id); | |
4713 | ||
4714 | for (i = 0; i < depth; i++) | |
4715 | child_id->stack[i] = parent_id->stack[i]; | |
4716 | child_id->stack[depth] = child_id->id; | |
4717 | /* | |
4718 | * child_id->css pointer will be set after this cgroup is available | |
4719 | * see cgroup_populate_dir() | |
4720 | */ | |
4721 | rcu_assign_pointer(child_css->id, child_id); | |
4722 | ||
4723 | return 0; | |
4724 | } | |
4725 | ||
4726 | /** | |
4727 | * css_lookup - lookup css by id | |
4728 | * @ss: cgroup subsys to be looked into. | |
4729 | * @id: the id | |
4730 | * | |
4731 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
4732 | * NULL if not. Should be called under rcu_read_lock() | |
4733 | */ | |
4734 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
4735 | { | |
4736 | struct css_id *cssid = NULL; | |
4737 | ||
4738 | BUG_ON(!ss->use_id); | |
4739 | cssid = idr_find(&ss->idr, id); | |
4740 | ||
4741 | if (unlikely(!cssid)) | |
4742 | return NULL; | |
4743 | ||
4744 | return rcu_dereference(cssid->css); | |
4745 | } | |
67523c48 | 4746 | EXPORT_SYMBOL_GPL(css_lookup); |
38460b48 KH |
4747 | |
4748 | /** | |
4749 | * css_get_next - lookup next cgroup under specified hierarchy. | |
4750 | * @ss: pointer to subsystem | |
4751 | * @id: current position of iteration. | |
4752 | * @root: pointer to css. search tree under this. | |
4753 | * @foundid: position of found object. | |
4754 | * | |
4755 | * Search next css under the specified hierarchy of rootid. Calling under | |
4756 | * rcu_read_lock() is necessary. Returns NULL if it reaches the end. | |
4757 | */ | |
4758 | struct cgroup_subsys_state * | |
4759 | css_get_next(struct cgroup_subsys *ss, int id, | |
4760 | struct cgroup_subsys_state *root, int *foundid) | |
4761 | { | |
4762 | struct cgroup_subsys_state *ret = NULL; | |
4763 | struct css_id *tmp; | |
4764 | int tmpid; | |
4765 | int rootid = css_id(root); | |
4766 | int depth = css_depth(root); | |
4767 | ||
4768 | if (!rootid) | |
4769 | return NULL; | |
4770 | ||
4771 | BUG_ON(!ss->use_id); | |
4772 | /* fill start point for scan */ | |
4773 | tmpid = id; | |
4774 | while (1) { | |
4775 | /* | |
4776 | * scan next entry from bitmap(tree), tmpid is updated after | |
4777 | * idr_get_next(). | |
4778 | */ | |
4779 | spin_lock(&ss->id_lock); | |
4780 | tmp = idr_get_next(&ss->idr, &tmpid); | |
4781 | spin_unlock(&ss->id_lock); | |
4782 | ||
4783 | if (!tmp) | |
4784 | break; | |
4785 | if (tmp->depth >= depth && tmp->stack[depth] == rootid) { | |
4786 | ret = rcu_dereference(tmp->css); | |
4787 | if (ret) { | |
4788 | *foundid = tmpid; | |
4789 | break; | |
4790 | } | |
4791 | } | |
4792 | /* continue to scan from next id */ | |
4793 | tmpid = tmpid + 1; | |
4794 | } | |
4795 | return ret; | |
4796 | } | |
4797 | ||
e5d1367f SE |
4798 | /* |
4799 | * get corresponding css from file open on cgroupfs directory | |
4800 | */ | |
4801 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) | |
4802 | { | |
4803 | struct cgroup *cgrp; | |
4804 | struct inode *inode; | |
4805 | struct cgroup_subsys_state *css; | |
4806 | ||
4807 | inode = f->f_dentry->d_inode; | |
4808 | /* check in cgroup filesystem dir */ | |
4809 | if (inode->i_op != &cgroup_dir_inode_operations) | |
4810 | return ERR_PTR(-EBADF); | |
4811 | ||
4812 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) | |
4813 | return ERR_PTR(-EINVAL); | |
4814 | ||
4815 | /* get cgroup */ | |
4816 | cgrp = __d_cgrp(f->f_dentry); | |
4817 | css = cgrp->subsys[id]; | |
4818 | return css ? css : ERR_PTR(-ENOENT); | |
4819 | } | |
4820 | ||
fe693435 PM |
4821 | #ifdef CONFIG_CGROUP_DEBUG |
4822 | static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss, | |
4823 | struct cgroup *cont) | |
4824 | { | |
4825 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
4826 | ||
4827 | if (!css) | |
4828 | return ERR_PTR(-ENOMEM); | |
4829 | ||
4830 | return css; | |
4831 | } | |
4832 | ||
4833 | static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont) | |
4834 | { | |
4835 | kfree(cont->subsys[debug_subsys_id]); | |
4836 | } | |
4837 | ||
4838 | static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) | |
4839 | { | |
4840 | return atomic_read(&cont->count); | |
4841 | } | |
4842 | ||
4843 | static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) | |
4844 | { | |
4845 | return cgroup_task_count(cont); | |
4846 | } | |
4847 | ||
4848 | static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) | |
4849 | { | |
4850 | return (u64)(unsigned long)current->cgroups; | |
4851 | } | |
4852 | ||
4853 | static u64 current_css_set_refcount_read(struct cgroup *cont, | |
4854 | struct cftype *cft) | |
4855 | { | |
4856 | u64 count; | |
4857 | ||
4858 | rcu_read_lock(); | |
4859 | count = atomic_read(¤t->cgroups->refcount); | |
4860 | rcu_read_unlock(); | |
4861 | return count; | |
4862 | } | |
4863 | ||
7717f7ba PM |
4864 | static int current_css_set_cg_links_read(struct cgroup *cont, |
4865 | struct cftype *cft, | |
4866 | struct seq_file *seq) | |
4867 | { | |
4868 | struct cg_cgroup_link *link; | |
4869 | struct css_set *cg; | |
4870 | ||
4871 | read_lock(&css_set_lock); | |
4872 | rcu_read_lock(); | |
4873 | cg = rcu_dereference(current->cgroups); | |
4874 | list_for_each_entry(link, &cg->cg_links, cg_link_list) { | |
4875 | struct cgroup *c = link->cgrp; | |
4876 | const char *name; | |
4877 | ||
4878 | if (c->dentry) | |
4879 | name = c->dentry->d_name.name; | |
4880 | else | |
4881 | name = "?"; | |
2c6ab6d2 PM |
4882 | seq_printf(seq, "Root %d group %s\n", |
4883 | c->root->hierarchy_id, name); | |
7717f7ba PM |
4884 | } |
4885 | rcu_read_unlock(); | |
4886 | read_unlock(&css_set_lock); | |
4887 | return 0; | |
4888 | } | |
4889 | ||
4890 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
4891 | static int cgroup_css_links_read(struct cgroup *cont, | |
4892 | struct cftype *cft, | |
4893 | struct seq_file *seq) | |
4894 | { | |
4895 | struct cg_cgroup_link *link; | |
4896 | ||
4897 | read_lock(&css_set_lock); | |
4898 | list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { | |
4899 | struct css_set *cg = link->cg; | |
4900 | struct task_struct *task; | |
4901 | int count = 0; | |
4902 | seq_printf(seq, "css_set %p\n", cg); | |
4903 | list_for_each_entry(task, &cg->tasks, cg_list) { | |
4904 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { | |
4905 | seq_puts(seq, " ...\n"); | |
4906 | break; | |
4907 | } else { | |
4908 | seq_printf(seq, " task %d\n", | |
4909 | task_pid_vnr(task)); | |
4910 | } | |
4911 | } | |
4912 | } | |
4913 | read_unlock(&css_set_lock); | |
4914 | return 0; | |
4915 | } | |
4916 | ||
fe693435 PM |
4917 | static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) |
4918 | { | |
4919 | return test_bit(CGRP_RELEASABLE, &cgrp->flags); | |
4920 | } | |
4921 | ||
4922 | static struct cftype debug_files[] = { | |
4923 | { | |
4924 | .name = "cgroup_refcount", | |
4925 | .read_u64 = cgroup_refcount_read, | |
4926 | }, | |
4927 | { | |
4928 | .name = "taskcount", | |
4929 | .read_u64 = debug_taskcount_read, | |
4930 | }, | |
4931 | ||
4932 | { | |
4933 | .name = "current_css_set", | |
4934 | .read_u64 = current_css_set_read, | |
4935 | }, | |
4936 | ||
4937 | { | |
4938 | .name = "current_css_set_refcount", | |
4939 | .read_u64 = current_css_set_refcount_read, | |
4940 | }, | |
4941 | ||
7717f7ba PM |
4942 | { |
4943 | .name = "current_css_set_cg_links", | |
4944 | .read_seq_string = current_css_set_cg_links_read, | |
4945 | }, | |
4946 | ||
4947 | { | |
4948 | .name = "cgroup_css_links", | |
4949 | .read_seq_string = cgroup_css_links_read, | |
4950 | }, | |
4951 | ||
fe693435 PM |
4952 | { |
4953 | .name = "releasable", | |
4954 | .read_u64 = releasable_read, | |
4955 | }, | |
4956 | }; | |
4957 | ||
4958 | static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont) | |
4959 | { | |
4960 | return cgroup_add_files(cont, ss, debug_files, | |
4961 | ARRAY_SIZE(debug_files)); | |
4962 | } | |
4963 | ||
4964 | struct cgroup_subsys debug_subsys = { | |
4965 | .name = "debug", | |
4966 | .create = debug_create, | |
4967 | .destroy = debug_destroy, | |
4968 | .populate = debug_populate, | |
4969 | .subsys_id = debug_subsys_id, | |
4970 | }; | |
4971 | #endif /* CONFIG_CGROUP_DEBUG */ |