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1 | /* | |
2 | * Generic process-grouping system. | |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
7 | * Notifications support | |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
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> | |
30 | #include <linux/cred.h> | |
31 | #include <linux/ctype.h> | |
32 | #include <linux/errno.h> | |
33 | #include <linux/fs.h> | |
34 | #include <linux/init_task.h> | |
35 | #include <linux/kernel.h> | |
36 | #include <linux/list.h> | |
37 | #include <linux/mm.h> | |
38 | #include <linux/mutex.h> | |
39 | #include <linux/mount.h> | |
40 | #include <linux/pagemap.h> | |
41 | #include <linux/proc_fs.h> | |
42 | #include <linux/rcupdate.h> | |
43 | #include <linux/sched.h> | |
44 | #include <linux/backing-dev.h> | |
45 | #include <linux/seq_file.h> | |
46 | #include <linux/slab.h> | |
47 | #include <linux/magic.h> | |
48 | #include <linux/spinlock.h> | |
49 | #include <linux/string.h> | |
50 | #include <linux/sort.h> | |
51 | #include <linux/kmod.h> | |
52 | #include <linux/module.h> | |
53 | #include <linux/delayacct.h> | |
54 | #include <linux/cgroupstats.h> | |
55 | #include <linux/hash.h> | |
56 | #include <linux/namei.h> | |
57 | #include <linux/pid_namespace.h> | |
58 | #include <linux/idr.h> | |
59 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ | |
60 | #include <linux/eventfd.h> | |
61 | #include <linux/poll.h> | |
62 | #include <linux/flex_array.h> /* used in cgroup_attach_proc */ | |
63 | #include <linux/kthread.h> | |
64 | ||
65 | #include <linux/atomic.h> | |
66 | ||
67 | /* css deactivation bias, makes css->refcnt negative to deny new trygets */ | |
68 | #define CSS_DEACT_BIAS INT_MIN | |
69 | ||
70 | /* | |
71 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
72 | * hierarchy must be performed while holding it. | |
73 | * | |
74 | * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify | |
75 | * cgroupfs_root of any cgroup hierarchy - subsys list, flags, | |
76 | * release_agent_path and so on. Modifying requires both cgroup_mutex and | |
77 | * cgroup_root_mutex. Readers can acquire either of the two. This is to | |
78 | * break the following locking order cycle. | |
79 | * | |
80 | * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem | |
81 | * B. namespace_sem -> cgroup_mutex | |
82 | * | |
83 | * B happens only through cgroup_show_options() and using cgroup_root_mutex | |
84 | * breaks it. | |
85 | */ | |
86 | static DEFINE_MUTEX(cgroup_mutex); | |
87 | static DEFINE_MUTEX(cgroup_root_mutex); | |
88 | ||
89 | /* | |
90 | * Generate an array of cgroup subsystem pointers. At boot time, this is | |
91 | * populated with the built in subsystems, and modular subsystems are | |
92 | * registered after that. The mutable section of this array is protected by | |
93 | * cgroup_mutex. | |
94 | */ | |
95 | #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys, | |
96 | #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) | |
97 | static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { | |
98 | #include <linux/cgroup_subsys.h> | |
99 | }; | |
100 | ||
101 | #define MAX_CGROUP_ROOT_NAMELEN 64 | |
102 | ||
103 | /* | |
104 | * A cgroupfs_root represents the root of a cgroup hierarchy, | |
105 | * and may be associated with a superblock to form an active | |
106 | * hierarchy | |
107 | */ | |
108 | struct cgroupfs_root { | |
109 | struct super_block *sb; | |
110 | ||
111 | /* | |
112 | * The bitmask of subsystems intended to be attached to this | |
113 | * hierarchy | |
114 | */ | |
115 | unsigned long subsys_mask; | |
116 | ||
117 | /* Unique id for this hierarchy. */ | |
118 | int hierarchy_id; | |
119 | ||
120 | /* The bitmask of subsystems currently attached to this hierarchy */ | |
121 | unsigned long actual_subsys_mask; | |
122 | ||
123 | /* A list running through the attached subsystems */ | |
124 | struct list_head subsys_list; | |
125 | ||
126 | /* The root cgroup for this hierarchy */ | |
127 | struct cgroup top_cgroup; | |
128 | ||
129 | /* Tracks how many cgroups are currently defined in hierarchy.*/ | |
130 | int number_of_cgroups; | |
131 | ||
132 | /* A list running through the active hierarchies */ | |
133 | struct list_head root_list; | |
134 | ||
135 | /* All cgroups on this root, cgroup_mutex protected */ | |
136 | struct list_head allcg_list; | |
137 | ||
138 | /* Hierarchy-specific flags */ | |
139 | unsigned long flags; | |
140 | ||
141 | /* The path to use for release notifications. */ | |
142 | char release_agent_path[PATH_MAX]; | |
143 | ||
144 | /* The name for this hierarchy - may be empty */ | |
145 | char name[MAX_CGROUP_ROOT_NAMELEN]; | |
146 | }; | |
147 | ||
148 | /* | |
149 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the | |
150 | * subsystems that are otherwise unattached - it never has more than a | |
151 | * single cgroup, and all tasks are part of that cgroup. | |
152 | */ | |
153 | static struct cgroupfs_root rootnode; | |
154 | ||
155 | /* | |
156 | * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. | |
157 | */ | |
158 | struct cfent { | |
159 | struct list_head node; | |
160 | struct dentry *dentry; | |
161 | struct cftype *type; | |
162 | }; | |
163 | ||
164 | /* | |
165 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when | |
166 | * cgroup_subsys->use_id != 0. | |
167 | */ | |
168 | #define CSS_ID_MAX (65535) | |
169 | struct css_id { | |
170 | /* | |
171 | * The css to which this ID points. This pointer is set to valid value | |
172 | * after cgroup is populated. If cgroup is removed, this will be NULL. | |
173 | * This pointer is expected to be RCU-safe because destroy() | |
174 | * is called after synchronize_rcu(). But for safe use, css_tryget() | |
175 | * should be used for avoiding race. | |
176 | */ | |
177 | struct cgroup_subsys_state __rcu *css; | |
178 | /* | |
179 | * ID of this css. | |
180 | */ | |
181 | unsigned short id; | |
182 | /* | |
183 | * Depth in hierarchy which this ID belongs to. | |
184 | */ | |
185 | unsigned short depth; | |
186 | /* | |
187 | * ID is freed by RCU. (and lookup routine is RCU safe.) | |
188 | */ | |
189 | struct rcu_head rcu_head; | |
190 | /* | |
191 | * Hierarchy of CSS ID belongs to. | |
192 | */ | |
193 | unsigned short stack[0]; /* Array of Length (depth+1) */ | |
194 | }; | |
195 | ||
196 | /* | |
197 | * cgroup_event represents events which userspace want to receive. | |
198 | */ | |
199 | struct cgroup_event { | |
200 | /* | |
201 | * Cgroup which the event belongs to. | |
202 | */ | |
203 | struct cgroup *cgrp; | |
204 | /* | |
205 | * Control file which the event associated. | |
206 | */ | |
207 | struct cftype *cft; | |
208 | /* | |
209 | * eventfd to signal userspace about the event. | |
210 | */ | |
211 | struct eventfd_ctx *eventfd; | |
212 | /* | |
213 | * Each of these stored in a list by the cgroup. | |
214 | */ | |
215 | struct list_head list; | |
216 | /* | |
217 | * All fields below needed to unregister event when | |
218 | * userspace closes eventfd. | |
219 | */ | |
220 | poll_table pt; | |
221 | wait_queue_head_t *wqh; | |
222 | wait_queue_t wait; | |
223 | struct work_struct remove; | |
224 | }; | |
225 | ||
226 | /* The list of hierarchy roots */ | |
227 | ||
228 | static LIST_HEAD(roots); | |
229 | static int root_count; | |
230 | ||
231 | static DEFINE_IDA(hierarchy_ida); | |
232 | static int next_hierarchy_id; | |
233 | static DEFINE_SPINLOCK(hierarchy_id_lock); | |
234 | ||
235 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ | |
236 | #define dummytop (&rootnode.top_cgroup) | |
237 | ||
238 | /* This flag indicates whether tasks in the fork and exit paths should | |
239 | * check for fork/exit handlers to call. This avoids us having to do | |
240 | * extra work in the fork/exit path if none of the subsystems need to | |
241 | * be called. | |
242 | */ | |
243 | static int need_forkexit_callback __read_mostly; | |
244 | ||
245 | #ifdef CONFIG_PROVE_LOCKING | |
246 | int cgroup_lock_is_held(void) | |
247 | { | |
248 | return lockdep_is_held(&cgroup_mutex); | |
249 | } | |
250 | #else /* #ifdef CONFIG_PROVE_LOCKING */ | |
251 | int cgroup_lock_is_held(void) | |
252 | { | |
253 | return mutex_is_locked(&cgroup_mutex); | |
254 | } | |
255 | #endif /* #else #ifdef CONFIG_PROVE_LOCKING */ | |
256 | ||
257 | EXPORT_SYMBOL_GPL(cgroup_lock_is_held); | |
258 | ||
259 | static int css_unbias_refcnt(int refcnt) | |
260 | { | |
261 | return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS; | |
262 | } | |
263 | ||
264 | /* the current nr of refs, always >= 0 whether @css is deactivated or not */ | |
265 | static int css_refcnt(struct cgroup_subsys_state *css) | |
266 | { | |
267 | int v = atomic_read(&css->refcnt); | |
268 | ||
269 | return css_unbias_refcnt(v); | |
270 | } | |
271 | ||
272 | /* convenient tests for these bits */ | |
273 | inline int cgroup_is_removed(const struct cgroup *cgrp) | |
274 | { | |
275 | return test_bit(CGRP_REMOVED, &cgrp->flags); | |
276 | } | |
277 | ||
278 | /* bits in struct cgroupfs_root flags field */ | |
279 | enum { | |
280 | ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ | |
281 | ROOT_XATTR, /* supports extended attributes */ | |
282 | }; | |
283 | ||
284 | static int cgroup_is_releasable(const struct cgroup *cgrp) | |
285 | { | |
286 | const int bits = | |
287 | (1 << CGRP_RELEASABLE) | | |
288 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
289 | return (cgrp->flags & bits) == bits; | |
290 | } | |
291 | ||
292 | static int notify_on_release(const struct cgroup *cgrp) | |
293 | { | |
294 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
295 | } | |
296 | ||
297 | static int clone_children(const struct cgroup *cgrp) | |
298 | { | |
299 | return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
300 | } | |
301 | ||
302 | /* | |
303 | * for_each_subsys() allows you to iterate on each subsystem attached to | |
304 | * an active hierarchy | |
305 | */ | |
306 | #define for_each_subsys(_root, _ss) \ | |
307 | list_for_each_entry(_ss, &_root->subsys_list, sibling) | |
308 | ||
309 | /* for_each_active_root() allows you to iterate across the active hierarchies */ | |
310 | #define for_each_active_root(_root) \ | |
311 | list_for_each_entry(_root, &roots, root_list) | |
312 | ||
313 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) | |
314 | { | |
315 | return dentry->d_fsdata; | |
316 | } | |
317 | ||
318 | static inline struct cfent *__d_cfe(struct dentry *dentry) | |
319 | { | |
320 | return dentry->d_fsdata; | |
321 | } | |
322 | ||
323 | static inline struct cftype *__d_cft(struct dentry *dentry) | |
324 | { | |
325 | return __d_cfe(dentry)->type; | |
326 | } | |
327 | ||
328 | /* the list of cgroups eligible for automatic release. Protected by | |
329 | * release_list_lock */ | |
330 | static LIST_HEAD(release_list); | |
331 | static DEFINE_RAW_SPINLOCK(release_list_lock); | |
332 | static void cgroup_release_agent(struct work_struct *work); | |
333 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
334 | static void check_for_release(struct cgroup *cgrp); | |
335 | ||
336 | /* Link structure for associating css_set objects with cgroups */ | |
337 | struct cg_cgroup_link { | |
338 | /* | |
339 | * List running through cg_cgroup_links associated with a | |
340 | * cgroup, anchored on cgroup->css_sets | |
341 | */ | |
342 | struct list_head cgrp_link_list; | |
343 | struct cgroup *cgrp; | |
344 | /* | |
345 | * List running through cg_cgroup_links pointing at a | |
346 | * single css_set object, anchored on css_set->cg_links | |
347 | */ | |
348 | struct list_head cg_link_list; | |
349 | struct css_set *cg; | |
350 | }; | |
351 | ||
352 | /* The default css_set - used by init and its children prior to any | |
353 | * hierarchies being mounted. It contains a pointer to the root state | |
354 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
355 | * reference-counted, to improve performance when child cgroups | |
356 | * haven't been created. | |
357 | */ | |
358 | ||
359 | static struct css_set init_css_set; | |
360 | static struct cg_cgroup_link init_css_set_link; | |
361 | ||
362 | static int cgroup_init_idr(struct cgroup_subsys *ss, | |
363 | struct cgroup_subsys_state *css); | |
364 | ||
365 | /* css_set_lock protects the list of css_set objects, and the | |
366 | * chain of tasks off each css_set. Nests outside task->alloc_lock | |
367 | * due to cgroup_iter_start() */ | |
368 | static DEFINE_RWLOCK(css_set_lock); | |
369 | static int css_set_count; | |
370 | ||
371 | /* | |
372 | * hash table for cgroup groups. This improves the performance to find | |
373 | * an existing css_set. This hash doesn't (currently) take into | |
374 | * account cgroups in empty hierarchies. | |
375 | */ | |
376 | #define CSS_SET_HASH_BITS 7 | |
377 | #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) | |
378 | static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; | |
379 | ||
380 | static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) | |
381 | { | |
382 | int i; | |
383 | int index; | |
384 | unsigned long tmp = 0UL; | |
385 | ||
386 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) | |
387 | tmp += (unsigned long)css[i]; | |
388 | tmp = (tmp >> 16) ^ tmp; | |
389 | ||
390 | index = hash_long(tmp, CSS_SET_HASH_BITS); | |
391 | ||
392 | return &css_set_table[index]; | |
393 | } | |
394 | ||
395 | /* We don't maintain the lists running through each css_set to its | |
396 | * task until after the first call to cgroup_iter_start(). This | |
397 | * reduces the fork()/exit() overhead for people who have cgroups | |
398 | * compiled into their kernel but not actually in use */ | |
399 | static int use_task_css_set_links __read_mostly; | |
400 | ||
401 | static void __put_css_set(struct css_set *cg, int taskexit) | |
402 | { | |
403 | struct cg_cgroup_link *link; | |
404 | struct cg_cgroup_link *saved_link; | |
405 | /* | |
406 | * Ensure that the refcount doesn't hit zero while any readers | |
407 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
408 | * rwlock | |
409 | */ | |
410 | if (atomic_add_unless(&cg->refcount, -1, 1)) | |
411 | return; | |
412 | write_lock(&css_set_lock); | |
413 | if (!atomic_dec_and_test(&cg->refcount)) { | |
414 | write_unlock(&css_set_lock); | |
415 | return; | |
416 | } | |
417 | ||
418 | /* This css_set is dead. unlink it and release cgroup refcounts */ | |
419 | hlist_del(&cg->hlist); | |
420 | css_set_count--; | |
421 | ||
422 | list_for_each_entry_safe(link, saved_link, &cg->cg_links, | |
423 | cg_link_list) { | |
424 | struct cgroup *cgrp = link->cgrp; | |
425 | list_del(&link->cg_link_list); | |
426 | list_del(&link->cgrp_link_list); | |
427 | if (atomic_dec_and_test(&cgrp->count) && | |
428 | notify_on_release(cgrp)) { | |
429 | if (taskexit) | |
430 | set_bit(CGRP_RELEASABLE, &cgrp->flags); | |
431 | check_for_release(cgrp); | |
432 | } | |
433 | ||
434 | kfree(link); | |
435 | } | |
436 | ||
437 | write_unlock(&css_set_lock); | |
438 | kfree_rcu(cg, rcu_head); | |
439 | } | |
440 | ||
441 | /* | |
442 | * refcounted get/put for css_set objects | |
443 | */ | |
444 | static inline void get_css_set(struct css_set *cg) | |
445 | { | |
446 | atomic_inc(&cg->refcount); | |
447 | } | |
448 | ||
449 | static inline void put_css_set(struct css_set *cg) | |
450 | { | |
451 | __put_css_set(cg, 0); | |
452 | } | |
453 | ||
454 | static inline void put_css_set_taskexit(struct css_set *cg) | |
455 | { | |
456 | __put_css_set(cg, 1); | |
457 | } | |
458 | ||
459 | /* | |
460 | * compare_css_sets - helper function for find_existing_css_set(). | |
461 | * @cg: candidate css_set being tested | |
462 | * @old_cg: existing css_set for a task | |
463 | * @new_cgrp: cgroup that's being entered by the task | |
464 | * @template: desired set of css pointers in css_set (pre-calculated) | |
465 | * | |
466 | * Returns true if "cg" matches "old_cg" except for the hierarchy | |
467 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". | |
468 | */ | |
469 | static bool compare_css_sets(struct css_set *cg, | |
470 | struct css_set *old_cg, | |
471 | struct cgroup *new_cgrp, | |
472 | struct cgroup_subsys_state *template[]) | |
473 | { | |
474 | struct list_head *l1, *l2; | |
475 | ||
476 | if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { | |
477 | /* Not all subsystems matched */ | |
478 | return false; | |
479 | } | |
480 | ||
481 | /* | |
482 | * Compare cgroup pointers in order to distinguish between | |
483 | * different cgroups in heirarchies with no subsystems. We | |
484 | * could get by with just this check alone (and skip the | |
485 | * memcmp above) but on most setups the memcmp check will | |
486 | * avoid the need for this more expensive check on almost all | |
487 | * candidates. | |
488 | */ | |
489 | ||
490 | l1 = &cg->cg_links; | |
491 | l2 = &old_cg->cg_links; | |
492 | while (1) { | |
493 | struct cg_cgroup_link *cgl1, *cgl2; | |
494 | struct cgroup *cg1, *cg2; | |
495 | ||
496 | l1 = l1->next; | |
497 | l2 = l2->next; | |
498 | /* See if we reached the end - both lists are equal length. */ | |
499 | if (l1 == &cg->cg_links) { | |
500 | BUG_ON(l2 != &old_cg->cg_links); | |
501 | break; | |
502 | } else { | |
503 | BUG_ON(l2 == &old_cg->cg_links); | |
504 | } | |
505 | /* Locate the cgroups associated with these links. */ | |
506 | cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); | |
507 | cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); | |
508 | cg1 = cgl1->cgrp; | |
509 | cg2 = cgl2->cgrp; | |
510 | /* Hierarchies should be linked in the same order. */ | |
511 | BUG_ON(cg1->root != cg2->root); | |
512 | ||
513 | /* | |
514 | * If this hierarchy is the hierarchy of the cgroup | |
515 | * that's changing, then we need to check that this | |
516 | * css_set points to the new cgroup; if it's any other | |
517 | * hierarchy, then this css_set should point to the | |
518 | * same cgroup as the old css_set. | |
519 | */ | |
520 | if (cg1->root == new_cgrp->root) { | |
521 | if (cg1 != new_cgrp) | |
522 | return false; | |
523 | } else { | |
524 | if (cg1 != cg2) | |
525 | return false; | |
526 | } | |
527 | } | |
528 | return true; | |
529 | } | |
530 | ||
531 | /* | |
532 | * find_existing_css_set() is a helper for | |
533 | * find_css_set(), and checks to see whether an existing | |
534 | * css_set is suitable. | |
535 | * | |
536 | * oldcg: the cgroup group that we're using before the cgroup | |
537 | * transition | |
538 | * | |
539 | * cgrp: the cgroup that we're moving into | |
540 | * | |
541 | * template: location in which to build the desired set of subsystem | |
542 | * state objects for the new cgroup group | |
543 | */ | |
544 | static struct css_set *find_existing_css_set( | |
545 | struct css_set *oldcg, | |
546 | struct cgroup *cgrp, | |
547 | struct cgroup_subsys_state *template[]) | |
548 | { | |
549 | int i; | |
550 | struct cgroupfs_root *root = cgrp->root; | |
551 | struct hlist_head *hhead; | |
552 | struct hlist_node *node; | |
553 | struct css_set *cg; | |
554 | ||
555 | /* | |
556 | * Build the set of subsystem state objects that we want to see in the | |
557 | * new css_set. while subsystems can change globally, the entries here | |
558 | * won't change, so no need for locking. | |
559 | */ | |
560 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
561 | if (root->subsys_mask & (1UL << i)) { | |
562 | /* Subsystem is in this hierarchy. So we want | |
563 | * the subsystem state from the new | |
564 | * cgroup */ | |
565 | template[i] = cgrp->subsys[i]; | |
566 | } else { | |
567 | /* Subsystem is not in this hierarchy, so we | |
568 | * don't want to change the subsystem state */ | |
569 | template[i] = oldcg->subsys[i]; | |
570 | } | |
571 | } | |
572 | ||
573 | hhead = css_set_hash(template); | |
574 | hlist_for_each_entry(cg, node, hhead, hlist) { | |
575 | if (!compare_css_sets(cg, oldcg, cgrp, template)) | |
576 | continue; | |
577 | ||
578 | /* This css_set matches what we need */ | |
579 | return cg; | |
580 | } | |
581 | ||
582 | /* No existing cgroup group matched */ | |
583 | return NULL; | |
584 | } | |
585 | ||
586 | static void free_cg_links(struct list_head *tmp) | |
587 | { | |
588 | struct cg_cgroup_link *link; | |
589 | struct cg_cgroup_link *saved_link; | |
590 | ||
591 | list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { | |
592 | list_del(&link->cgrp_link_list); | |
593 | kfree(link); | |
594 | } | |
595 | } | |
596 | ||
597 | /* | |
598 | * allocate_cg_links() allocates "count" cg_cgroup_link structures | |
599 | * and chains them on tmp through their cgrp_link_list fields. Returns 0 on | |
600 | * success or a negative error | |
601 | */ | |
602 | static int allocate_cg_links(int count, struct list_head *tmp) | |
603 | { | |
604 | struct cg_cgroup_link *link; | |
605 | int i; | |
606 | INIT_LIST_HEAD(tmp); | |
607 | for (i = 0; i < count; i++) { | |
608 | link = kmalloc(sizeof(*link), GFP_KERNEL); | |
609 | if (!link) { | |
610 | free_cg_links(tmp); | |
611 | return -ENOMEM; | |
612 | } | |
613 | list_add(&link->cgrp_link_list, tmp); | |
614 | } | |
615 | return 0; | |
616 | } | |
617 | ||
618 | /** | |
619 | * link_css_set - a helper function to link a css_set to a cgroup | |
620 | * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() | |
621 | * @cg: the css_set to be linked | |
622 | * @cgrp: the destination cgroup | |
623 | */ | |
624 | static void link_css_set(struct list_head *tmp_cg_links, | |
625 | struct css_set *cg, struct cgroup *cgrp) | |
626 | { | |
627 | struct cg_cgroup_link *link; | |
628 | ||
629 | BUG_ON(list_empty(tmp_cg_links)); | |
630 | link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, | |
631 | cgrp_link_list); | |
632 | link->cg = cg; | |
633 | link->cgrp = cgrp; | |
634 | atomic_inc(&cgrp->count); | |
635 | list_move(&link->cgrp_link_list, &cgrp->css_sets); | |
636 | /* | |
637 | * Always add links to the tail of the list so that the list | |
638 | * is sorted by order of hierarchy creation | |
639 | */ | |
640 | list_add_tail(&link->cg_link_list, &cg->cg_links); | |
641 | } | |
642 | ||
643 | /* | |
644 | * find_css_set() takes an existing cgroup group and a | |
645 | * cgroup object, and returns a css_set object that's | |
646 | * equivalent to the old group, but with the given cgroup | |
647 | * substituted into the appropriate hierarchy. Must be called with | |
648 | * cgroup_mutex held | |
649 | */ | |
650 | static struct css_set *find_css_set( | |
651 | struct css_set *oldcg, struct cgroup *cgrp) | |
652 | { | |
653 | struct css_set *res; | |
654 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; | |
655 | ||
656 | struct list_head tmp_cg_links; | |
657 | ||
658 | struct hlist_head *hhead; | |
659 | struct cg_cgroup_link *link; | |
660 | ||
661 | /* First see if we already have a cgroup group that matches | |
662 | * the desired set */ | |
663 | read_lock(&css_set_lock); | |
664 | res = find_existing_css_set(oldcg, cgrp, template); | |
665 | if (res) | |
666 | get_css_set(res); | |
667 | read_unlock(&css_set_lock); | |
668 | ||
669 | if (res) | |
670 | return res; | |
671 | ||
672 | res = kmalloc(sizeof(*res), GFP_KERNEL); | |
673 | if (!res) | |
674 | return NULL; | |
675 | ||
676 | /* Allocate all the cg_cgroup_link objects that we'll need */ | |
677 | if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { | |
678 | kfree(res); | |
679 | return NULL; | |
680 | } | |
681 | ||
682 | atomic_set(&res->refcount, 1); | |
683 | INIT_LIST_HEAD(&res->cg_links); | |
684 | INIT_LIST_HEAD(&res->tasks); | |
685 | INIT_HLIST_NODE(&res->hlist); | |
686 | ||
687 | /* Copy the set of subsystem state objects generated in | |
688 | * find_existing_css_set() */ | |
689 | memcpy(res->subsys, template, sizeof(res->subsys)); | |
690 | ||
691 | write_lock(&css_set_lock); | |
692 | /* Add reference counts and links from the new css_set. */ | |
693 | list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { | |
694 | struct cgroup *c = link->cgrp; | |
695 | if (c->root == cgrp->root) | |
696 | c = cgrp; | |
697 | link_css_set(&tmp_cg_links, res, c); | |
698 | } | |
699 | ||
700 | BUG_ON(!list_empty(&tmp_cg_links)); | |
701 | ||
702 | css_set_count++; | |
703 | ||
704 | /* Add this cgroup group to the hash table */ | |
705 | hhead = css_set_hash(res->subsys); | |
706 | hlist_add_head(&res->hlist, hhead); | |
707 | ||
708 | write_unlock(&css_set_lock); | |
709 | ||
710 | return res; | |
711 | } | |
712 | ||
713 | /* | |
714 | * Return the cgroup for "task" from the given hierarchy. Must be | |
715 | * called with cgroup_mutex held. | |
716 | */ | |
717 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
718 | struct cgroupfs_root *root) | |
719 | { | |
720 | struct css_set *css; | |
721 | struct cgroup *res = NULL; | |
722 | ||
723 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
724 | read_lock(&css_set_lock); | |
725 | /* | |
726 | * No need to lock the task - since we hold cgroup_mutex the | |
727 | * task can't change groups, so the only thing that can happen | |
728 | * is that it exits and its css is set back to init_css_set. | |
729 | */ | |
730 | css = task->cgroups; | |
731 | if (css == &init_css_set) { | |
732 | res = &root->top_cgroup; | |
733 | } else { | |
734 | struct cg_cgroup_link *link; | |
735 | list_for_each_entry(link, &css->cg_links, cg_link_list) { | |
736 | struct cgroup *c = link->cgrp; | |
737 | if (c->root == root) { | |
738 | res = c; | |
739 | break; | |
740 | } | |
741 | } | |
742 | } | |
743 | read_unlock(&css_set_lock); | |
744 | BUG_ON(!res); | |
745 | return res; | |
746 | } | |
747 | ||
748 | /* | |
749 | * There is one global cgroup mutex. We also require taking | |
750 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
751 | * See "The task_lock() exception", at the end of this comment. | |
752 | * | |
753 | * A task must hold cgroup_mutex to modify cgroups. | |
754 | * | |
755 | * Any task can increment and decrement the count field without lock. | |
756 | * So in general, code holding cgroup_mutex can't rely on the count | |
757 | * field not changing. However, if the count goes to zero, then only | |
758 | * cgroup_attach_task() can increment it again. Because a count of zero | |
759 | * means that no tasks are currently attached, therefore there is no | |
760 | * way a task attached to that cgroup can fork (the other way to | |
761 | * increment the count). So code holding cgroup_mutex can safely | |
762 | * assume that if the count is zero, it will stay zero. Similarly, if | |
763 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
764 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
765 | * needs that mutex. | |
766 | * | |
767 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't | |
768 | * (usually) take cgroup_mutex. These are the two most performance | |
769 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
770 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
771 | * is taken, and if the cgroup count is zero, a usermode call made | |
772 | * to the release agent with the name of the cgroup (path relative to | |
773 | * the root of cgroup file system) as the argument. | |
774 | * | |
775 | * A cgroup can only be deleted if both its 'count' of using tasks | |
776 | * is zero, and its list of 'children' cgroups is empty. Since all | |
777 | * tasks in the system use _some_ cgroup, and since there is always at | |
778 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
779 | * always has either children cgroups and/or using tasks. So we don't | |
780 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
781 | * | |
782 | * The task_lock() exception | |
783 | * | |
784 | * The need for this exception arises from the action of | |
785 | * cgroup_attach_task(), which overwrites one tasks cgroup pointer with | |
786 | * another. It does so using cgroup_mutex, however there are | |
787 | * several performance critical places that need to reference | |
788 | * task->cgroup without the expense of grabbing a system global | |
789 | * mutex. Therefore except as noted below, when dereferencing or, as | |
790 | * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use | |
791 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in | |
792 | * the task_struct routinely used for such matters. | |
793 | * | |
794 | * P.S. One more locking exception. RCU is used to guard the | |
795 | * update of a tasks cgroup pointer by cgroup_attach_task() | |
796 | */ | |
797 | ||
798 | /** | |
799 | * cgroup_lock - lock out any changes to cgroup structures | |
800 | * | |
801 | */ | |
802 | void cgroup_lock(void) | |
803 | { | |
804 | mutex_lock(&cgroup_mutex); | |
805 | } | |
806 | EXPORT_SYMBOL_GPL(cgroup_lock); | |
807 | ||
808 | /** | |
809 | * cgroup_unlock - release lock on cgroup changes | |
810 | * | |
811 | * Undo the lock taken in a previous cgroup_lock() call. | |
812 | */ | |
813 | void cgroup_unlock(void) | |
814 | { | |
815 | mutex_unlock(&cgroup_mutex); | |
816 | } | |
817 | EXPORT_SYMBOL_GPL(cgroup_unlock); | |
818 | ||
819 | /* | |
820 | * A couple of forward declarations required, due to cyclic reference loop: | |
821 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
822 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
823 | * -> cgroup_mkdir. | |
824 | */ | |
825 | ||
826 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); | |
827 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int); | |
828 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); | |
829 | static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, | |
830 | unsigned long subsys_mask); | |
831 | static const struct inode_operations cgroup_dir_inode_operations; | |
832 | static const struct file_operations proc_cgroupstats_operations; | |
833 | ||
834 | static struct backing_dev_info cgroup_backing_dev_info = { | |
835 | .name = "cgroup", | |
836 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, | |
837 | }; | |
838 | ||
839 | static int alloc_css_id(struct cgroup_subsys *ss, | |
840 | struct cgroup *parent, struct cgroup *child); | |
841 | ||
842 | static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) | |
843 | { | |
844 | struct inode *inode = new_inode(sb); | |
845 | ||
846 | if (inode) { | |
847 | inode->i_ino = get_next_ino(); | |
848 | inode->i_mode = mode; | |
849 | inode->i_uid = current_fsuid(); | |
850 | inode->i_gid = current_fsgid(); | |
851 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
852 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
853 | } | |
854 | return inode; | |
855 | } | |
856 | ||
857 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) | |
858 | { | |
859 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
860 | if (S_ISDIR(inode->i_mode)) { | |
861 | struct cgroup *cgrp = dentry->d_fsdata; | |
862 | struct cgroup_subsys *ss; | |
863 | BUG_ON(!(cgroup_is_removed(cgrp))); | |
864 | /* It's possible for external users to be holding css | |
865 | * reference counts on a cgroup; css_put() needs to | |
866 | * be able to access the cgroup after decrementing | |
867 | * the reference count in order to know if it needs to | |
868 | * queue the cgroup to be handled by the release | |
869 | * agent */ | |
870 | synchronize_rcu(); | |
871 | ||
872 | mutex_lock(&cgroup_mutex); | |
873 | /* | |
874 | * Release the subsystem state objects. | |
875 | */ | |
876 | for_each_subsys(cgrp->root, ss) | |
877 | ss->destroy(cgrp); | |
878 | ||
879 | cgrp->root->number_of_cgroups--; | |
880 | mutex_unlock(&cgroup_mutex); | |
881 | ||
882 | /* | |
883 | * Drop the active superblock reference that we took when we | |
884 | * created the cgroup | |
885 | */ | |
886 | deactivate_super(cgrp->root->sb); | |
887 | ||
888 | /* | |
889 | * if we're getting rid of the cgroup, refcount should ensure | |
890 | * that there are no pidlists left. | |
891 | */ | |
892 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
893 | ||
894 | simple_xattrs_free(&cgrp->xattrs); | |
895 | ||
896 | kfree_rcu(cgrp, rcu_head); | |
897 | } else { | |
898 | struct cfent *cfe = __d_cfe(dentry); | |
899 | struct cgroup *cgrp = dentry->d_parent->d_fsdata; | |
900 | struct cftype *cft = cfe->type; | |
901 | ||
902 | WARN_ONCE(!list_empty(&cfe->node) && | |
903 | cgrp != &cgrp->root->top_cgroup, | |
904 | "cfe still linked for %s\n", cfe->type->name); | |
905 | kfree(cfe); | |
906 | simple_xattrs_free(&cft->xattrs); | |
907 | } | |
908 | iput(inode); | |
909 | } | |
910 | ||
911 | static int cgroup_delete(const struct dentry *d) | |
912 | { | |
913 | return 1; | |
914 | } | |
915 | ||
916 | static void remove_dir(struct dentry *d) | |
917 | { | |
918 | struct dentry *parent = dget(d->d_parent); | |
919 | ||
920 | d_delete(d); | |
921 | simple_rmdir(parent->d_inode, d); | |
922 | dput(parent); | |
923 | } | |
924 | ||
925 | static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) | |
926 | { | |
927 | struct cfent *cfe; | |
928 | ||
929 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); | |
930 | lockdep_assert_held(&cgroup_mutex); | |
931 | ||
932 | list_for_each_entry(cfe, &cgrp->files, node) { | |
933 | struct dentry *d = cfe->dentry; | |
934 | ||
935 | if (cft && cfe->type != cft) | |
936 | continue; | |
937 | ||
938 | dget(d); | |
939 | d_delete(d); | |
940 | simple_unlink(cgrp->dentry->d_inode, d); | |
941 | list_del_init(&cfe->node); | |
942 | dput(d); | |
943 | ||
944 | return 0; | |
945 | } | |
946 | return -ENOENT; | |
947 | } | |
948 | ||
949 | /** | |
950 | * cgroup_clear_directory - selective removal of base and subsystem files | |
951 | * @dir: directory containing the files | |
952 | * @base_files: true if the base files should be removed | |
953 | * @subsys_mask: mask of the subsystem ids whose files should be removed | |
954 | */ | |
955 | static void cgroup_clear_directory(struct dentry *dir, bool base_files, | |
956 | unsigned long subsys_mask) | |
957 | { | |
958 | struct cgroup *cgrp = __d_cgrp(dir); | |
959 | struct cgroup_subsys *ss; | |
960 | ||
961 | for_each_subsys(cgrp->root, ss) { | |
962 | struct cftype_set *set; | |
963 | if (!test_bit(ss->subsys_id, &subsys_mask)) | |
964 | continue; | |
965 | list_for_each_entry(set, &ss->cftsets, node) | |
966 | cgroup_rm_file(cgrp, set->cfts); | |
967 | } | |
968 | if (base_files) { | |
969 | while (!list_empty(&cgrp->files)) | |
970 | cgroup_rm_file(cgrp, NULL); | |
971 | } | |
972 | } | |
973 | ||
974 | /* | |
975 | * NOTE : the dentry must have been dget()'ed | |
976 | */ | |
977 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
978 | { | |
979 | struct dentry *parent; | |
980 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; | |
981 | ||
982 | cgroup_clear_directory(dentry, true, root->subsys_mask); | |
983 | ||
984 | parent = dentry->d_parent; | |
985 | spin_lock(&parent->d_lock); | |
986 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
987 | list_del_init(&dentry->d_u.d_child); | |
988 | spin_unlock(&dentry->d_lock); | |
989 | spin_unlock(&parent->d_lock); | |
990 | remove_dir(dentry); | |
991 | } | |
992 | ||
993 | /* | |
994 | * Call with cgroup_mutex held. Drops reference counts on modules, including | |
995 | * any duplicate ones that parse_cgroupfs_options took. If this function | |
996 | * returns an error, no reference counts are touched. | |
997 | */ | |
998 | static int rebind_subsystems(struct cgroupfs_root *root, | |
999 | unsigned long final_subsys_mask) | |
1000 | { | |
1001 | unsigned long added_mask, removed_mask; | |
1002 | struct cgroup *cgrp = &root->top_cgroup; | |
1003 | int i; | |
1004 | ||
1005 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
1006 | BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); | |
1007 | ||
1008 | removed_mask = root->actual_subsys_mask & ~final_subsys_mask; | |
1009 | added_mask = final_subsys_mask & ~root->actual_subsys_mask; | |
1010 | /* Check that any added subsystems are currently free */ | |
1011 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1012 | unsigned long bit = 1UL << i; | |
1013 | struct cgroup_subsys *ss = subsys[i]; | |
1014 | if (!(bit & added_mask)) | |
1015 | continue; | |
1016 | /* | |
1017 | * Nobody should tell us to do a subsys that doesn't exist: | |
1018 | * parse_cgroupfs_options should catch that case and refcounts | |
1019 | * ensure that subsystems won't disappear once selected. | |
1020 | */ | |
1021 | BUG_ON(ss == NULL); | |
1022 | if (ss->root != &rootnode) { | |
1023 | /* Subsystem isn't free */ | |
1024 | return -EBUSY; | |
1025 | } | |
1026 | } | |
1027 | ||
1028 | /* Currently we don't handle adding/removing subsystems when | |
1029 | * any child cgroups exist. This is theoretically supportable | |
1030 | * but involves complex error handling, so it's being left until | |
1031 | * later */ | |
1032 | if (root->number_of_cgroups > 1) | |
1033 | return -EBUSY; | |
1034 | ||
1035 | /* Process each subsystem */ | |
1036 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1037 | struct cgroup_subsys *ss = subsys[i]; | |
1038 | unsigned long bit = 1UL << i; | |
1039 | if (bit & added_mask) { | |
1040 | /* We're binding this subsystem to this hierarchy */ | |
1041 | BUG_ON(ss == NULL); | |
1042 | BUG_ON(cgrp->subsys[i]); | |
1043 | BUG_ON(!dummytop->subsys[i]); | |
1044 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); | |
1045 | cgrp->subsys[i] = dummytop->subsys[i]; | |
1046 | cgrp->subsys[i]->cgroup = cgrp; | |
1047 | list_move(&ss->sibling, &root->subsys_list); | |
1048 | ss->root = root; | |
1049 | if (ss->bind) | |
1050 | ss->bind(cgrp); | |
1051 | /* refcount was already taken, and we're keeping it */ | |
1052 | } else if (bit & removed_mask) { | |
1053 | /* We're removing this subsystem */ | |
1054 | BUG_ON(ss == NULL); | |
1055 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); | |
1056 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); | |
1057 | if (ss->bind) | |
1058 | ss->bind(dummytop); | |
1059 | dummytop->subsys[i]->cgroup = dummytop; | |
1060 | cgrp->subsys[i] = NULL; | |
1061 | subsys[i]->root = &rootnode; | |
1062 | list_move(&ss->sibling, &rootnode.subsys_list); | |
1063 | /* subsystem is now free - drop reference on module */ | |
1064 | module_put(ss->module); | |
1065 | } else if (bit & final_subsys_mask) { | |
1066 | /* Subsystem state should already exist */ | |
1067 | BUG_ON(ss == NULL); | |
1068 | BUG_ON(!cgrp->subsys[i]); | |
1069 | /* | |
1070 | * a refcount was taken, but we already had one, so | |
1071 | * drop the extra reference. | |
1072 | */ | |
1073 | module_put(ss->module); | |
1074 | #ifdef CONFIG_MODULE_UNLOAD | |
1075 | BUG_ON(ss->module && !module_refcount(ss->module)); | |
1076 | #endif | |
1077 | } else { | |
1078 | /* Subsystem state shouldn't exist */ | |
1079 | BUG_ON(cgrp->subsys[i]); | |
1080 | } | |
1081 | } | |
1082 | root->subsys_mask = root->actual_subsys_mask = final_subsys_mask; | |
1083 | synchronize_rcu(); | |
1084 | ||
1085 | return 0; | |
1086 | } | |
1087 | ||
1088 | static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) | |
1089 | { | |
1090 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; | |
1091 | struct cgroup_subsys *ss; | |
1092 | ||
1093 | mutex_lock(&cgroup_root_mutex); | |
1094 | for_each_subsys(root, ss) | |
1095 | seq_printf(seq, ",%s", ss->name); | |
1096 | if (test_bit(ROOT_NOPREFIX, &root->flags)) | |
1097 | seq_puts(seq, ",noprefix"); | |
1098 | if (test_bit(ROOT_XATTR, &root->flags)) | |
1099 | seq_puts(seq, ",xattr"); | |
1100 | if (strlen(root->release_agent_path)) | |
1101 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
1102 | if (clone_children(&root->top_cgroup)) | |
1103 | seq_puts(seq, ",clone_children"); | |
1104 | if (strlen(root->name)) | |
1105 | seq_printf(seq, ",name=%s", root->name); | |
1106 | mutex_unlock(&cgroup_root_mutex); | |
1107 | return 0; | |
1108 | } | |
1109 | ||
1110 | struct cgroup_sb_opts { | |
1111 | unsigned long subsys_mask; | |
1112 | unsigned long flags; | |
1113 | char *release_agent; | |
1114 | bool clone_children; | |
1115 | char *name; | |
1116 | /* User explicitly requested empty subsystem */ | |
1117 | bool none; | |
1118 | ||
1119 | struct cgroupfs_root *new_root; | |
1120 | ||
1121 | }; | |
1122 | ||
1123 | /* | |
1124 | * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call | |
1125 | * with cgroup_mutex held to protect the subsys[] array. This function takes | |
1126 | * refcounts on subsystems to be used, unless it returns error, in which case | |
1127 | * no refcounts are taken. | |
1128 | */ | |
1129 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) | |
1130 | { | |
1131 | char *token, *o = data; | |
1132 | bool all_ss = false, one_ss = false; | |
1133 | unsigned long mask = (unsigned long)-1; | |
1134 | int i; | |
1135 | bool module_pin_failed = false; | |
1136 | ||
1137 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
1138 | ||
1139 | #ifdef CONFIG_CPUSETS | |
1140 | mask = ~(1UL << cpuset_subsys_id); | |
1141 | #endif | |
1142 | ||
1143 | memset(opts, 0, sizeof(*opts)); | |
1144 | ||
1145 | while ((token = strsep(&o, ",")) != NULL) { | |
1146 | if (!*token) | |
1147 | return -EINVAL; | |
1148 | if (!strcmp(token, "none")) { | |
1149 | /* Explicitly have no subsystems */ | |
1150 | opts->none = true; | |
1151 | continue; | |
1152 | } | |
1153 | if (!strcmp(token, "all")) { | |
1154 | /* Mutually exclusive option 'all' + subsystem name */ | |
1155 | if (one_ss) | |
1156 | return -EINVAL; | |
1157 | all_ss = true; | |
1158 | continue; | |
1159 | } | |
1160 | if (!strcmp(token, "noprefix")) { | |
1161 | set_bit(ROOT_NOPREFIX, &opts->flags); | |
1162 | continue; | |
1163 | } | |
1164 | if (!strcmp(token, "clone_children")) { | |
1165 | opts->clone_children = true; | |
1166 | continue; | |
1167 | } | |
1168 | if (!strcmp(token, "xattr")) { | |
1169 | set_bit(ROOT_XATTR, &opts->flags); | |
1170 | continue; | |
1171 | } | |
1172 | if (!strncmp(token, "release_agent=", 14)) { | |
1173 | /* Specifying two release agents is forbidden */ | |
1174 | if (opts->release_agent) | |
1175 | return -EINVAL; | |
1176 | opts->release_agent = | |
1177 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); | |
1178 | if (!opts->release_agent) | |
1179 | return -ENOMEM; | |
1180 | continue; | |
1181 | } | |
1182 | if (!strncmp(token, "name=", 5)) { | |
1183 | const char *name = token + 5; | |
1184 | /* Can't specify an empty name */ | |
1185 | if (!strlen(name)) | |
1186 | return -EINVAL; | |
1187 | /* Must match [\w.-]+ */ | |
1188 | for (i = 0; i < strlen(name); i++) { | |
1189 | char c = name[i]; | |
1190 | if (isalnum(c)) | |
1191 | continue; | |
1192 | if ((c == '.') || (c == '-') || (c == '_')) | |
1193 | continue; | |
1194 | return -EINVAL; | |
1195 | } | |
1196 | /* Specifying two names is forbidden */ | |
1197 | if (opts->name) | |
1198 | return -EINVAL; | |
1199 | opts->name = kstrndup(name, | |
1200 | MAX_CGROUP_ROOT_NAMELEN - 1, | |
1201 | GFP_KERNEL); | |
1202 | if (!opts->name) | |
1203 | return -ENOMEM; | |
1204 | ||
1205 | continue; | |
1206 | } | |
1207 | ||
1208 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1209 | struct cgroup_subsys *ss = subsys[i]; | |
1210 | if (ss == NULL) | |
1211 | continue; | |
1212 | if (strcmp(token, ss->name)) | |
1213 | continue; | |
1214 | if (ss->disabled) | |
1215 | continue; | |
1216 | ||
1217 | /* Mutually exclusive option 'all' + subsystem name */ | |
1218 | if (all_ss) | |
1219 | return -EINVAL; | |
1220 | set_bit(i, &opts->subsys_mask); | |
1221 | one_ss = true; | |
1222 | ||
1223 | break; | |
1224 | } | |
1225 | if (i == CGROUP_SUBSYS_COUNT) | |
1226 | return -ENOENT; | |
1227 | } | |
1228 | ||
1229 | /* | |
1230 | * If the 'all' option was specified select all the subsystems, | |
1231 | * otherwise if 'none', 'name=' and a subsystem name options | |
1232 | * were not specified, let's default to 'all' | |
1233 | */ | |
1234 | if (all_ss || (!one_ss && !opts->none && !opts->name)) { | |
1235 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1236 | struct cgroup_subsys *ss = subsys[i]; | |
1237 | if (ss == NULL) | |
1238 | continue; | |
1239 | if (ss->disabled) | |
1240 | continue; | |
1241 | set_bit(i, &opts->subsys_mask); | |
1242 | } | |
1243 | } | |
1244 | ||
1245 | /* Consistency checks */ | |
1246 | ||
1247 | /* | |
1248 | * Option noprefix was introduced just for backward compatibility | |
1249 | * with the old cpuset, so we allow noprefix only if mounting just | |
1250 | * the cpuset subsystem. | |
1251 | */ | |
1252 | if (test_bit(ROOT_NOPREFIX, &opts->flags) && | |
1253 | (opts->subsys_mask & mask)) | |
1254 | return -EINVAL; | |
1255 | ||
1256 | ||
1257 | /* Can't specify "none" and some subsystems */ | |
1258 | if (opts->subsys_mask && opts->none) | |
1259 | return -EINVAL; | |
1260 | ||
1261 | /* | |
1262 | * We either have to specify by name or by subsystems. (So all | |
1263 | * empty hierarchies must have a name). | |
1264 | */ | |
1265 | if (!opts->subsys_mask && !opts->name) | |
1266 | return -EINVAL; | |
1267 | ||
1268 | /* | |
1269 | * Grab references on all the modules we'll need, so the subsystems | |
1270 | * don't dance around before rebind_subsystems attaches them. This may | |
1271 | * take duplicate reference counts on a subsystem that's already used, | |
1272 | * but rebind_subsystems handles this case. | |
1273 | */ | |
1274 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1275 | unsigned long bit = 1UL << i; | |
1276 | ||
1277 | if (!(bit & opts->subsys_mask)) | |
1278 | continue; | |
1279 | if (!try_module_get(subsys[i]->module)) { | |
1280 | module_pin_failed = true; | |
1281 | break; | |
1282 | } | |
1283 | } | |
1284 | if (module_pin_failed) { | |
1285 | /* | |
1286 | * oops, one of the modules was going away. this means that we | |
1287 | * raced with a module_delete call, and to the user this is | |
1288 | * essentially a "subsystem doesn't exist" case. | |
1289 | */ | |
1290 | for (i--; i >= 0; i--) { | |
1291 | /* drop refcounts only on the ones we took */ | |
1292 | unsigned long bit = 1UL << i; | |
1293 | ||
1294 | if (!(bit & opts->subsys_mask)) | |
1295 | continue; | |
1296 | module_put(subsys[i]->module); | |
1297 | } | |
1298 | return -ENOENT; | |
1299 | } | |
1300 | ||
1301 | return 0; | |
1302 | } | |
1303 | ||
1304 | static void drop_parsed_module_refcounts(unsigned long subsys_mask) | |
1305 | { | |
1306 | int i; | |
1307 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1308 | unsigned long bit = 1UL << i; | |
1309 | ||
1310 | if (!(bit & subsys_mask)) | |
1311 | continue; | |
1312 | module_put(subsys[i]->module); | |
1313 | } | |
1314 | } | |
1315 | ||
1316 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) | |
1317 | { | |
1318 | int ret = 0; | |
1319 | struct cgroupfs_root *root = sb->s_fs_info; | |
1320 | struct cgroup *cgrp = &root->top_cgroup; | |
1321 | struct cgroup_sb_opts opts; | |
1322 | unsigned long added_mask, removed_mask; | |
1323 | ||
1324 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); | |
1325 | mutex_lock(&cgroup_mutex); | |
1326 | mutex_lock(&cgroup_root_mutex); | |
1327 | ||
1328 | /* See what subsystems are wanted */ | |
1329 | ret = parse_cgroupfs_options(data, &opts); | |
1330 | if (ret) | |
1331 | goto out_unlock; | |
1332 | ||
1333 | /* See feature-removal-schedule.txt */ | |
1334 | if (opts.subsys_mask != root->actual_subsys_mask || opts.release_agent) | |
1335 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", | |
1336 | task_tgid_nr(current), current->comm); | |
1337 | ||
1338 | added_mask = opts.subsys_mask & ~root->subsys_mask; | |
1339 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
1340 | ||
1341 | /* Don't allow flags or name to change at remount */ | |
1342 | if (opts.flags != root->flags || | |
1343 | (opts.name && strcmp(opts.name, root->name))) { | |
1344 | ret = -EINVAL; | |
1345 | drop_parsed_module_refcounts(opts.subsys_mask); | |
1346 | goto out_unlock; | |
1347 | } | |
1348 | ||
1349 | ret = rebind_subsystems(root, opts.subsys_mask); | |
1350 | if (ret) { | |
1351 | drop_parsed_module_refcounts(opts.subsys_mask); | |
1352 | goto out_unlock; | |
1353 | } | |
1354 | ||
1355 | /* clear out any existing files and repopulate subsystem files */ | |
1356 | cgroup_clear_directory(cgrp->dentry, false, removed_mask); | |
1357 | /* re-populate subsystem files */ | |
1358 | cgroup_populate_dir(cgrp, false, added_mask); | |
1359 | ||
1360 | if (opts.release_agent) | |
1361 | strcpy(root->release_agent_path, opts.release_agent); | |
1362 | out_unlock: | |
1363 | kfree(opts.release_agent); | |
1364 | kfree(opts.name); | |
1365 | mutex_unlock(&cgroup_root_mutex); | |
1366 | mutex_unlock(&cgroup_mutex); | |
1367 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); | |
1368 | return ret; | |
1369 | } | |
1370 | ||
1371 | static const struct super_operations cgroup_ops = { | |
1372 | .statfs = simple_statfs, | |
1373 | .drop_inode = generic_delete_inode, | |
1374 | .show_options = cgroup_show_options, | |
1375 | .remount_fs = cgroup_remount, | |
1376 | }; | |
1377 | ||
1378 | static void init_cgroup_housekeeping(struct cgroup *cgrp) | |
1379 | { | |
1380 | INIT_LIST_HEAD(&cgrp->sibling); | |
1381 | INIT_LIST_HEAD(&cgrp->children); | |
1382 | INIT_LIST_HEAD(&cgrp->files); | |
1383 | INIT_LIST_HEAD(&cgrp->css_sets); | |
1384 | INIT_LIST_HEAD(&cgrp->allcg_node); | |
1385 | INIT_LIST_HEAD(&cgrp->release_list); | |
1386 | INIT_LIST_HEAD(&cgrp->pidlists); | |
1387 | mutex_init(&cgrp->pidlist_mutex); | |
1388 | INIT_LIST_HEAD(&cgrp->event_list); | |
1389 | spin_lock_init(&cgrp->event_list_lock); | |
1390 | simple_xattrs_init(&cgrp->xattrs); | |
1391 | } | |
1392 | ||
1393 | static void init_cgroup_root(struct cgroupfs_root *root) | |
1394 | { | |
1395 | struct cgroup *cgrp = &root->top_cgroup; | |
1396 | ||
1397 | INIT_LIST_HEAD(&root->subsys_list); | |
1398 | INIT_LIST_HEAD(&root->root_list); | |
1399 | INIT_LIST_HEAD(&root->allcg_list); | |
1400 | root->number_of_cgroups = 1; | |
1401 | cgrp->root = root; | |
1402 | cgrp->top_cgroup = cgrp; | |
1403 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); | |
1404 | init_cgroup_housekeeping(cgrp); | |
1405 | } | |
1406 | ||
1407 | static bool init_root_id(struct cgroupfs_root *root) | |
1408 | { | |
1409 | int ret = 0; | |
1410 | ||
1411 | do { | |
1412 | if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) | |
1413 | return false; | |
1414 | spin_lock(&hierarchy_id_lock); | |
1415 | /* Try to allocate the next unused ID */ | |
1416 | ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, | |
1417 | &root->hierarchy_id); | |
1418 | if (ret == -ENOSPC) | |
1419 | /* Try again starting from 0 */ | |
1420 | ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id); | |
1421 | if (!ret) { | |
1422 | next_hierarchy_id = root->hierarchy_id + 1; | |
1423 | } else if (ret != -EAGAIN) { | |
1424 | /* Can only get here if the 31-bit IDR is full ... */ | |
1425 | BUG_ON(ret); | |
1426 | } | |
1427 | spin_unlock(&hierarchy_id_lock); | |
1428 | } while (ret); | |
1429 | return true; | |
1430 | } | |
1431 | ||
1432 | static int cgroup_test_super(struct super_block *sb, void *data) | |
1433 | { | |
1434 | struct cgroup_sb_opts *opts = data; | |
1435 | struct cgroupfs_root *root = sb->s_fs_info; | |
1436 | ||
1437 | /* If we asked for a name then it must match */ | |
1438 | if (opts->name && strcmp(opts->name, root->name)) | |
1439 | return 0; | |
1440 | ||
1441 | /* | |
1442 | * If we asked for subsystems (or explicitly for no | |
1443 | * subsystems) then they must match | |
1444 | */ | |
1445 | if ((opts->subsys_mask || opts->none) | |
1446 | && (opts->subsys_mask != root->subsys_mask)) | |
1447 | return 0; | |
1448 | ||
1449 | return 1; | |
1450 | } | |
1451 | ||
1452 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) | |
1453 | { | |
1454 | struct cgroupfs_root *root; | |
1455 | ||
1456 | if (!opts->subsys_mask && !opts->none) | |
1457 | return NULL; | |
1458 | ||
1459 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1460 | if (!root) | |
1461 | return ERR_PTR(-ENOMEM); | |
1462 | ||
1463 | if (!init_root_id(root)) { | |
1464 | kfree(root); | |
1465 | return ERR_PTR(-ENOMEM); | |
1466 | } | |
1467 | init_cgroup_root(root); | |
1468 | ||
1469 | root->subsys_mask = opts->subsys_mask; | |
1470 | root->flags = opts->flags; | |
1471 | if (opts->release_agent) | |
1472 | strcpy(root->release_agent_path, opts->release_agent); | |
1473 | if (opts->name) | |
1474 | strcpy(root->name, opts->name); | |
1475 | if (opts->clone_children) | |
1476 | set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags); | |
1477 | return root; | |
1478 | } | |
1479 | ||
1480 | static void cgroup_drop_root(struct cgroupfs_root *root) | |
1481 | { | |
1482 | if (!root) | |
1483 | return; | |
1484 | ||
1485 | BUG_ON(!root->hierarchy_id); | |
1486 | spin_lock(&hierarchy_id_lock); | |
1487 | ida_remove(&hierarchy_ida, root->hierarchy_id); | |
1488 | spin_unlock(&hierarchy_id_lock); | |
1489 | kfree(root); | |
1490 | } | |
1491 | ||
1492 | static int cgroup_set_super(struct super_block *sb, void *data) | |
1493 | { | |
1494 | int ret; | |
1495 | struct cgroup_sb_opts *opts = data; | |
1496 | ||
1497 | /* If we don't have a new root, we can't set up a new sb */ | |
1498 | if (!opts->new_root) | |
1499 | return -EINVAL; | |
1500 | ||
1501 | BUG_ON(!opts->subsys_mask && !opts->none); | |
1502 | ||
1503 | ret = set_anon_super(sb, NULL); | |
1504 | if (ret) | |
1505 | return ret; | |
1506 | ||
1507 | sb->s_fs_info = opts->new_root; | |
1508 | opts->new_root->sb = sb; | |
1509 | ||
1510 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
1511 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
1512 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
1513 | sb->s_op = &cgroup_ops; | |
1514 | ||
1515 | return 0; | |
1516 | } | |
1517 | ||
1518 | static int cgroup_get_rootdir(struct super_block *sb) | |
1519 | { | |
1520 | static const struct dentry_operations cgroup_dops = { | |
1521 | .d_iput = cgroup_diput, | |
1522 | .d_delete = cgroup_delete, | |
1523 | }; | |
1524 | ||
1525 | struct inode *inode = | |
1526 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
1527 | ||
1528 | if (!inode) | |
1529 | return -ENOMEM; | |
1530 | ||
1531 | inode->i_fop = &simple_dir_operations; | |
1532 | inode->i_op = &cgroup_dir_inode_operations; | |
1533 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1534 | inc_nlink(inode); | |
1535 | sb->s_root = d_make_root(inode); | |
1536 | if (!sb->s_root) | |
1537 | return -ENOMEM; | |
1538 | /* for everything else we want ->d_op set */ | |
1539 | sb->s_d_op = &cgroup_dops; | |
1540 | return 0; | |
1541 | } | |
1542 | ||
1543 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, | |
1544 | int flags, const char *unused_dev_name, | |
1545 | void *data) | |
1546 | { | |
1547 | struct cgroup_sb_opts opts; | |
1548 | struct cgroupfs_root *root; | |
1549 | int ret = 0; | |
1550 | struct super_block *sb; | |
1551 | struct cgroupfs_root *new_root; | |
1552 | struct inode *inode; | |
1553 | ||
1554 | /* First find the desired set of subsystems */ | |
1555 | mutex_lock(&cgroup_mutex); | |
1556 | ret = parse_cgroupfs_options(data, &opts); | |
1557 | mutex_unlock(&cgroup_mutex); | |
1558 | if (ret) | |
1559 | goto out_err; | |
1560 | ||
1561 | /* | |
1562 | * Allocate a new cgroup root. We may not need it if we're | |
1563 | * reusing an existing hierarchy. | |
1564 | */ | |
1565 | new_root = cgroup_root_from_opts(&opts); | |
1566 | if (IS_ERR(new_root)) { | |
1567 | ret = PTR_ERR(new_root); | |
1568 | goto drop_modules; | |
1569 | } | |
1570 | opts.new_root = new_root; | |
1571 | ||
1572 | /* Locate an existing or new sb for this hierarchy */ | |
1573 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts); | |
1574 | if (IS_ERR(sb)) { | |
1575 | ret = PTR_ERR(sb); | |
1576 | cgroup_drop_root(opts.new_root); | |
1577 | goto drop_modules; | |
1578 | } | |
1579 | ||
1580 | root = sb->s_fs_info; | |
1581 | BUG_ON(!root); | |
1582 | if (root == opts.new_root) { | |
1583 | /* We used the new root structure, so this is a new hierarchy */ | |
1584 | struct list_head tmp_cg_links; | |
1585 | struct cgroup *root_cgrp = &root->top_cgroup; | |
1586 | struct cgroupfs_root *existing_root; | |
1587 | const struct cred *cred; | |
1588 | int i; | |
1589 | ||
1590 | BUG_ON(sb->s_root != NULL); | |
1591 | ||
1592 | ret = cgroup_get_rootdir(sb); | |
1593 | if (ret) | |
1594 | goto drop_new_super; | |
1595 | inode = sb->s_root->d_inode; | |
1596 | ||
1597 | mutex_lock(&inode->i_mutex); | |
1598 | mutex_lock(&cgroup_mutex); | |
1599 | mutex_lock(&cgroup_root_mutex); | |
1600 | ||
1601 | /* Check for name clashes with existing mounts */ | |
1602 | ret = -EBUSY; | |
1603 | if (strlen(root->name)) | |
1604 | for_each_active_root(existing_root) | |
1605 | if (!strcmp(existing_root->name, root->name)) | |
1606 | goto unlock_drop; | |
1607 | ||
1608 | /* | |
1609 | * We're accessing css_set_count without locking | |
1610 | * css_set_lock here, but that's OK - it can only be | |
1611 | * increased by someone holding cgroup_lock, and | |
1612 | * that's us. The worst that can happen is that we | |
1613 | * have some link structures left over | |
1614 | */ | |
1615 | ret = allocate_cg_links(css_set_count, &tmp_cg_links); | |
1616 | if (ret) | |
1617 | goto unlock_drop; | |
1618 | ||
1619 | ret = rebind_subsystems(root, root->subsys_mask); | |
1620 | if (ret == -EBUSY) { | |
1621 | free_cg_links(&tmp_cg_links); | |
1622 | goto unlock_drop; | |
1623 | } | |
1624 | /* | |
1625 | * There must be no failure case after here, since rebinding | |
1626 | * takes care of subsystems' refcounts, which are explicitly | |
1627 | * dropped in the failure exit path. | |
1628 | */ | |
1629 | ||
1630 | /* EBUSY should be the only error here */ | |
1631 | BUG_ON(ret); | |
1632 | ||
1633 | list_add(&root->root_list, &roots); | |
1634 | root_count++; | |
1635 | ||
1636 | sb->s_root->d_fsdata = root_cgrp; | |
1637 | root->top_cgroup.dentry = sb->s_root; | |
1638 | ||
1639 | /* Link the top cgroup in this hierarchy into all | |
1640 | * the css_set objects */ | |
1641 | write_lock(&css_set_lock); | |
1642 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { | |
1643 | struct hlist_head *hhead = &css_set_table[i]; | |
1644 | struct hlist_node *node; | |
1645 | struct css_set *cg; | |
1646 | ||
1647 | hlist_for_each_entry(cg, node, hhead, hlist) | |
1648 | link_css_set(&tmp_cg_links, cg, root_cgrp); | |
1649 | } | |
1650 | write_unlock(&css_set_lock); | |
1651 | ||
1652 | free_cg_links(&tmp_cg_links); | |
1653 | ||
1654 | BUG_ON(!list_empty(&root_cgrp->children)); | |
1655 | BUG_ON(root->number_of_cgroups != 1); | |
1656 | ||
1657 | cred = override_creds(&init_cred); | |
1658 | cgroup_populate_dir(root_cgrp, true, root->subsys_mask); | |
1659 | revert_creds(cred); | |
1660 | mutex_unlock(&cgroup_root_mutex); | |
1661 | mutex_unlock(&cgroup_mutex); | |
1662 | mutex_unlock(&inode->i_mutex); | |
1663 | } else { | |
1664 | /* | |
1665 | * We re-used an existing hierarchy - the new root (if | |
1666 | * any) is not needed | |
1667 | */ | |
1668 | cgroup_drop_root(opts.new_root); | |
1669 | /* no subsys rebinding, so refcounts don't change */ | |
1670 | drop_parsed_module_refcounts(opts.subsys_mask); | |
1671 | } | |
1672 | ||
1673 | kfree(opts.release_agent); | |
1674 | kfree(opts.name); | |
1675 | return dget(sb->s_root); | |
1676 | ||
1677 | unlock_drop: | |
1678 | mutex_unlock(&cgroup_root_mutex); | |
1679 | mutex_unlock(&cgroup_mutex); | |
1680 | mutex_unlock(&inode->i_mutex); | |
1681 | drop_new_super: | |
1682 | deactivate_locked_super(sb); | |
1683 | drop_modules: | |
1684 | drop_parsed_module_refcounts(opts.subsys_mask); | |
1685 | out_err: | |
1686 | kfree(opts.release_agent); | |
1687 | kfree(opts.name); | |
1688 | return ERR_PTR(ret); | |
1689 | } | |
1690 | ||
1691 | static void cgroup_kill_sb(struct super_block *sb) { | |
1692 | struct cgroupfs_root *root = sb->s_fs_info; | |
1693 | struct cgroup *cgrp = &root->top_cgroup; | |
1694 | int ret; | |
1695 | struct cg_cgroup_link *link; | |
1696 | struct cg_cgroup_link *saved_link; | |
1697 | ||
1698 | BUG_ON(!root); | |
1699 | ||
1700 | BUG_ON(root->number_of_cgroups != 1); | |
1701 | BUG_ON(!list_empty(&cgrp->children)); | |
1702 | ||
1703 | mutex_lock(&cgroup_mutex); | |
1704 | mutex_lock(&cgroup_root_mutex); | |
1705 | ||
1706 | /* Rebind all subsystems back to the default hierarchy */ | |
1707 | ret = rebind_subsystems(root, 0); | |
1708 | /* Shouldn't be able to fail ... */ | |
1709 | BUG_ON(ret); | |
1710 | ||
1711 | /* | |
1712 | * Release all the links from css_sets to this hierarchy's | |
1713 | * root cgroup | |
1714 | */ | |
1715 | write_lock(&css_set_lock); | |
1716 | ||
1717 | list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, | |
1718 | cgrp_link_list) { | |
1719 | list_del(&link->cg_link_list); | |
1720 | list_del(&link->cgrp_link_list); | |
1721 | kfree(link); | |
1722 | } | |
1723 | write_unlock(&css_set_lock); | |
1724 | ||
1725 | if (!list_empty(&root->root_list)) { | |
1726 | list_del(&root->root_list); | |
1727 | root_count--; | |
1728 | } | |
1729 | ||
1730 | mutex_unlock(&cgroup_root_mutex); | |
1731 | mutex_unlock(&cgroup_mutex); | |
1732 | ||
1733 | simple_xattrs_free(&cgrp->xattrs); | |
1734 | ||
1735 | kill_litter_super(sb); | |
1736 | cgroup_drop_root(root); | |
1737 | } | |
1738 | ||
1739 | static struct file_system_type cgroup_fs_type = { | |
1740 | .name = "cgroup", | |
1741 | .mount = cgroup_mount, | |
1742 | .kill_sb = cgroup_kill_sb, | |
1743 | }; | |
1744 | ||
1745 | static struct kobject *cgroup_kobj; | |
1746 | ||
1747 | /** | |
1748 | * cgroup_path - generate the path of a cgroup | |
1749 | * @cgrp: the cgroup in question | |
1750 | * @buf: the buffer to write the path into | |
1751 | * @buflen: the length of the buffer | |
1752 | * | |
1753 | * Called with cgroup_mutex held or else with an RCU-protected cgroup | |
1754 | * reference. Writes path of cgroup into buf. Returns 0 on success, | |
1755 | * -errno on error. | |
1756 | */ | |
1757 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) | |
1758 | { | |
1759 | char *start; | |
1760 | struct dentry *dentry = rcu_dereference_check(cgrp->dentry, | |
1761 | cgroup_lock_is_held()); | |
1762 | ||
1763 | if (!dentry || cgrp == dummytop) { | |
1764 | /* | |
1765 | * Inactive subsystems have no dentry for their root | |
1766 | * cgroup | |
1767 | */ | |
1768 | strcpy(buf, "/"); | |
1769 | return 0; | |
1770 | } | |
1771 | ||
1772 | start = buf + buflen - 1; | |
1773 | ||
1774 | *start = '\0'; | |
1775 | for (;;) { | |
1776 | int len = dentry->d_name.len; | |
1777 | ||
1778 | if ((start -= len) < buf) | |
1779 | return -ENAMETOOLONG; | |
1780 | memcpy(start, dentry->d_name.name, len); | |
1781 | cgrp = cgrp->parent; | |
1782 | if (!cgrp) | |
1783 | break; | |
1784 | ||
1785 | dentry = rcu_dereference_check(cgrp->dentry, | |
1786 | cgroup_lock_is_held()); | |
1787 | if (!cgrp->parent) | |
1788 | continue; | |
1789 | if (--start < buf) | |
1790 | return -ENAMETOOLONG; | |
1791 | *start = '/'; | |
1792 | } | |
1793 | memmove(buf, start, buf + buflen - start); | |
1794 | return 0; | |
1795 | } | |
1796 | EXPORT_SYMBOL_GPL(cgroup_path); | |
1797 | ||
1798 | /* | |
1799 | * Control Group taskset | |
1800 | */ | |
1801 | struct task_and_cgroup { | |
1802 | struct task_struct *task; | |
1803 | struct cgroup *cgrp; | |
1804 | struct css_set *cg; | |
1805 | }; | |
1806 | ||
1807 | struct cgroup_taskset { | |
1808 | struct task_and_cgroup single; | |
1809 | struct flex_array *tc_array; | |
1810 | int tc_array_len; | |
1811 | int idx; | |
1812 | struct cgroup *cur_cgrp; | |
1813 | }; | |
1814 | ||
1815 | /** | |
1816 | * cgroup_taskset_first - reset taskset and return the first task | |
1817 | * @tset: taskset of interest | |
1818 | * | |
1819 | * @tset iteration is initialized and the first task is returned. | |
1820 | */ | |
1821 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1822 | { | |
1823 | if (tset->tc_array) { | |
1824 | tset->idx = 0; | |
1825 | return cgroup_taskset_next(tset); | |
1826 | } else { | |
1827 | tset->cur_cgrp = tset->single.cgrp; | |
1828 | return tset->single.task; | |
1829 | } | |
1830 | } | |
1831 | EXPORT_SYMBOL_GPL(cgroup_taskset_first); | |
1832 | ||
1833 | /** | |
1834 | * cgroup_taskset_next - iterate to the next task in taskset | |
1835 | * @tset: taskset of interest | |
1836 | * | |
1837 | * Return the next task in @tset. Iteration must have been initialized | |
1838 | * with cgroup_taskset_first(). | |
1839 | */ | |
1840 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1841 | { | |
1842 | struct task_and_cgroup *tc; | |
1843 | ||
1844 | if (!tset->tc_array || tset->idx >= tset->tc_array_len) | |
1845 | return NULL; | |
1846 | ||
1847 | tc = flex_array_get(tset->tc_array, tset->idx++); | |
1848 | tset->cur_cgrp = tc->cgrp; | |
1849 | return tc->task; | |
1850 | } | |
1851 | EXPORT_SYMBOL_GPL(cgroup_taskset_next); | |
1852 | ||
1853 | /** | |
1854 | * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task | |
1855 | * @tset: taskset of interest | |
1856 | * | |
1857 | * Return the cgroup for the current (last returned) task of @tset. This | |
1858 | * function must be preceded by either cgroup_taskset_first() or | |
1859 | * cgroup_taskset_next(). | |
1860 | */ | |
1861 | struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) | |
1862 | { | |
1863 | return tset->cur_cgrp; | |
1864 | } | |
1865 | EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); | |
1866 | ||
1867 | /** | |
1868 | * cgroup_taskset_size - return the number of tasks in taskset | |
1869 | * @tset: taskset of interest | |
1870 | */ | |
1871 | int cgroup_taskset_size(struct cgroup_taskset *tset) | |
1872 | { | |
1873 | return tset->tc_array ? tset->tc_array_len : 1; | |
1874 | } | |
1875 | EXPORT_SYMBOL_GPL(cgroup_taskset_size); | |
1876 | ||
1877 | ||
1878 | /* | |
1879 | * cgroup_task_migrate - move a task from one cgroup to another. | |
1880 | * | |
1881 | * 'guarantee' is set if the caller promises that a new css_set for the task | |
1882 | * will already exist. If not set, this function might sleep, and can fail with | |
1883 | * -ENOMEM. Must be called with cgroup_mutex and threadgroup locked. | |
1884 | */ | |
1885 | static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, | |
1886 | struct task_struct *tsk, struct css_set *newcg) | |
1887 | { | |
1888 | struct css_set *oldcg; | |
1889 | ||
1890 | /* | |
1891 | * We are synchronized through threadgroup_lock() against PF_EXITING | |
1892 | * setting such that we can't race against cgroup_exit() changing the | |
1893 | * css_set to init_css_set and dropping the old one. | |
1894 | */ | |
1895 | WARN_ON_ONCE(tsk->flags & PF_EXITING); | |
1896 | oldcg = tsk->cgroups; | |
1897 | ||
1898 | task_lock(tsk); | |
1899 | rcu_assign_pointer(tsk->cgroups, newcg); | |
1900 | task_unlock(tsk); | |
1901 | ||
1902 | /* Update the css_set linked lists if we're using them */ | |
1903 | write_lock(&css_set_lock); | |
1904 | if (!list_empty(&tsk->cg_list)) | |
1905 | list_move(&tsk->cg_list, &newcg->tasks); | |
1906 | write_unlock(&css_set_lock); | |
1907 | ||
1908 | /* | |
1909 | * We just gained a reference on oldcg by taking it from the task. As | |
1910 | * trading it for newcg is protected by cgroup_mutex, we're safe to drop | |
1911 | * it here; it will be freed under RCU. | |
1912 | */ | |
1913 | set_bit(CGRP_RELEASABLE, &oldcgrp->flags); | |
1914 | put_css_set(oldcg); | |
1915 | } | |
1916 | ||
1917 | /** | |
1918 | * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' | |
1919 | * @cgrp: the cgroup the task is attaching to | |
1920 | * @tsk: the task to be attached | |
1921 | * | |
1922 | * Call with cgroup_mutex and threadgroup locked. May take task_lock of | |
1923 | * @tsk during call. | |
1924 | */ | |
1925 | int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) | |
1926 | { | |
1927 | int retval = 0; | |
1928 | struct cgroup_subsys *ss, *failed_ss = NULL; | |
1929 | struct cgroup *oldcgrp; | |
1930 | struct cgroupfs_root *root = cgrp->root; | |
1931 | struct cgroup_taskset tset = { }; | |
1932 | struct css_set *newcg; | |
1933 | ||
1934 | /* @tsk either already exited or can't exit until the end */ | |
1935 | if (tsk->flags & PF_EXITING) | |
1936 | return -ESRCH; | |
1937 | ||
1938 | /* Nothing to do if the task is already in that cgroup */ | |
1939 | oldcgrp = task_cgroup_from_root(tsk, root); | |
1940 | if (cgrp == oldcgrp) | |
1941 | return 0; | |
1942 | ||
1943 | tset.single.task = tsk; | |
1944 | tset.single.cgrp = oldcgrp; | |
1945 | ||
1946 | for_each_subsys(root, ss) { | |
1947 | if (ss->can_attach) { | |
1948 | retval = ss->can_attach(cgrp, &tset); | |
1949 | if (retval) { | |
1950 | /* | |
1951 | * Remember on which subsystem the can_attach() | |
1952 | * failed, so that we only call cancel_attach() | |
1953 | * against the subsystems whose can_attach() | |
1954 | * succeeded. (See below) | |
1955 | */ | |
1956 | failed_ss = ss; | |
1957 | goto out; | |
1958 | } | |
1959 | } | |
1960 | } | |
1961 | ||
1962 | newcg = find_css_set(tsk->cgroups, cgrp); | |
1963 | if (!newcg) { | |
1964 | retval = -ENOMEM; | |
1965 | goto out; | |
1966 | } | |
1967 | ||
1968 | cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg); | |
1969 | ||
1970 | for_each_subsys(root, ss) { | |
1971 | if (ss->attach) | |
1972 | ss->attach(cgrp, &tset); | |
1973 | } | |
1974 | ||
1975 | synchronize_rcu(); | |
1976 | out: | |
1977 | if (retval) { | |
1978 | for_each_subsys(root, ss) { | |
1979 | if (ss == failed_ss) | |
1980 | /* | |
1981 | * This subsystem was the one that failed the | |
1982 | * can_attach() check earlier, so we don't need | |
1983 | * to call cancel_attach() against it or any | |
1984 | * remaining subsystems. | |
1985 | */ | |
1986 | break; | |
1987 | if (ss->cancel_attach) | |
1988 | ss->cancel_attach(cgrp, &tset); | |
1989 | } | |
1990 | } | |
1991 | return retval; | |
1992 | } | |
1993 | ||
1994 | /** | |
1995 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
1996 | * @from: attach to all cgroups of a given task | |
1997 | * @tsk: the task to be attached | |
1998 | */ | |
1999 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2000 | { | |
2001 | struct cgroupfs_root *root; | |
2002 | int retval = 0; | |
2003 | ||
2004 | cgroup_lock(); | |
2005 | for_each_active_root(root) { | |
2006 | struct cgroup *from_cg = task_cgroup_from_root(from, root); | |
2007 | ||
2008 | retval = cgroup_attach_task(from_cg, tsk); | |
2009 | if (retval) | |
2010 | break; | |
2011 | } | |
2012 | cgroup_unlock(); | |
2013 | ||
2014 | return retval; | |
2015 | } | |
2016 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2017 | ||
2018 | /** | |
2019 | * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup | |
2020 | * @cgrp: the cgroup to attach to | |
2021 | * @leader: the threadgroup leader task_struct of the group to be attached | |
2022 | * | |
2023 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take | |
2024 | * task_lock of each thread in leader's threadgroup individually in turn. | |
2025 | */ | |
2026 | static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) | |
2027 | { | |
2028 | int retval, i, group_size; | |
2029 | struct cgroup_subsys *ss, *failed_ss = NULL; | |
2030 | /* guaranteed to be initialized later, but the compiler needs this */ | |
2031 | struct cgroupfs_root *root = cgrp->root; | |
2032 | /* threadgroup list cursor and array */ | |
2033 | struct task_struct *tsk; | |
2034 | struct task_and_cgroup *tc; | |
2035 | struct flex_array *group; | |
2036 | struct cgroup_taskset tset = { }; | |
2037 | ||
2038 | /* | |
2039 | * step 0: in order to do expensive, possibly blocking operations for | |
2040 | * every thread, we cannot iterate the thread group list, since it needs | |
2041 | * rcu or tasklist locked. instead, build an array of all threads in the | |
2042 | * group - group_rwsem prevents new threads from appearing, and if | |
2043 | * threads exit, this will just be an over-estimate. | |
2044 | */ | |
2045 | group_size = get_nr_threads(leader); | |
2046 | /* flex_array supports very large thread-groups better than kmalloc. */ | |
2047 | group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); | |
2048 | if (!group) | |
2049 | return -ENOMEM; | |
2050 | /* pre-allocate to guarantee space while iterating in rcu read-side. */ | |
2051 | retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL); | |
2052 | if (retval) | |
2053 | goto out_free_group_list; | |
2054 | ||
2055 | tsk = leader; | |
2056 | i = 0; | |
2057 | /* | |
2058 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2059 | * already PF_EXITING could be freed from underneath us unless we | |
2060 | * take an rcu_read_lock. | |
2061 | */ | |
2062 | rcu_read_lock(); | |
2063 | do { | |
2064 | struct task_and_cgroup ent; | |
2065 | ||
2066 | /* @tsk either already exited or can't exit until the end */ | |
2067 | if (tsk->flags & PF_EXITING) | |
2068 | continue; | |
2069 | ||
2070 | /* as per above, nr_threads may decrease, but not increase. */ | |
2071 | BUG_ON(i >= group_size); | |
2072 | ent.task = tsk; | |
2073 | ent.cgrp = task_cgroup_from_root(tsk, root); | |
2074 | /* nothing to do if this task is already in the cgroup */ | |
2075 | if (ent.cgrp == cgrp) | |
2076 | continue; | |
2077 | /* | |
2078 | * saying GFP_ATOMIC has no effect here because we did prealloc | |
2079 | * earlier, but it's good form to communicate our expectations. | |
2080 | */ | |
2081 | retval = flex_array_put(group, i, &ent, GFP_ATOMIC); | |
2082 | BUG_ON(retval != 0); | |
2083 | i++; | |
2084 | } while_each_thread(leader, tsk); | |
2085 | rcu_read_unlock(); | |
2086 | /* remember the number of threads in the array for later. */ | |
2087 | group_size = i; | |
2088 | tset.tc_array = group; | |
2089 | tset.tc_array_len = group_size; | |
2090 | ||
2091 | /* methods shouldn't be called if no task is actually migrating */ | |
2092 | retval = 0; | |
2093 | if (!group_size) | |
2094 | goto out_free_group_list; | |
2095 | ||
2096 | /* | |
2097 | * step 1: check that we can legitimately attach to the cgroup. | |
2098 | */ | |
2099 | for_each_subsys(root, ss) { | |
2100 | if (ss->can_attach) { | |
2101 | retval = ss->can_attach(cgrp, &tset); | |
2102 | if (retval) { | |
2103 | failed_ss = ss; | |
2104 | goto out_cancel_attach; | |
2105 | } | |
2106 | } | |
2107 | } | |
2108 | ||
2109 | /* | |
2110 | * step 2: make sure css_sets exist for all threads to be migrated. | |
2111 | * we use find_css_set, which allocates a new one if necessary. | |
2112 | */ | |
2113 | for (i = 0; i < group_size; i++) { | |
2114 | tc = flex_array_get(group, i); | |
2115 | tc->cg = find_css_set(tc->task->cgroups, cgrp); | |
2116 | if (!tc->cg) { | |
2117 | retval = -ENOMEM; | |
2118 | goto out_put_css_set_refs; | |
2119 | } | |
2120 | } | |
2121 | ||
2122 | /* | |
2123 | * step 3: now that we're guaranteed success wrt the css_sets, | |
2124 | * proceed to move all tasks to the new cgroup. There are no | |
2125 | * failure cases after here, so this is the commit point. | |
2126 | */ | |
2127 | for (i = 0; i < group_size; i++) { | |
2128 | tc = flex_array_get(group, i); | |
2129 | cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg); | |
2130 | } | |
2131 | /* nothing is sensitive to fork() after this point. */ | |
2132 | ||
2133 | /* | |
2134 | * step 4: do subsystem attach callbacks. | |
2135 | */ | |
2136 | for_each_subsys(root, ss) { | |
2137 | if (ss->attach) | |
2138 | ss->attach(cgrp, &tset); | |
2139 | } | |
2140 | ||
2141 | /* | |
2142 | * step 5: success! and cleanup | |
2143 | */ | |
2144 | synchronize_rcu(); | |
2145 | retval = 0; | |
2146 | out_put_css_set_refs: | |
2147 | if (retval) { | |
2148 | for (i = 0; i < group_size; i++) { | |
2149 | tc = flex_array_get(group, i); | |
2150 | if (!tc->cg) | |
2151 | break; | |
2152 | put_css_set(tc->cg); | |
2153 | } | |
2154 | } | |
2155 | out_cancel_attach: | |
2156 | if (retval) { | |
2157 | for_each_subsys(root, ss) { | |
2158 | if (ss == failed_ss) | |
2159 | break; | |
2160 | if (ss->cancel_attach) | |
2161 | ss->cancel_attach(cgrp, &tset); | |
2162 | } | |
2163 | } | |
2164 | out_free_group_list: | |
2165 | flex_array_free(group); | |
2166 | return retval; | |
2167 | } | |
2168 | ||
2169 | /* | |
2170 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
2171 | * function to attach either it or all tasks in its threadgroup. Will lock | |
2172 | * cgroup_mutex and threadgroup; may take task_lock of task. | |
2173 | */ | |
2174 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) | |
2175 | { | |
2176 | struct task_struct *tsk; | |
2177 | const struct cred *cred = current_cred(), *tcred; | |
2178 | int ret; | |
2179 | ||
2180 | if (!cgroup_lock_live_group(cgrp)) | |
2181 | return -ENODEV; | |
2182 | ||
2183 | retry_find_task: | |
2184 | rcu_read_lock(); | |
2185 | if (pid) { | |
2186 | tsk = find_task_by_vpid(pid); | |
2187 | if (!tsk) { | |
2188 | rcu_read_unlock(); | |
2189 | ret= -ESRCH; | |
2190 | goto out_unlock_cgroup; | |
2191 | } | |
2192 | /* | |
2193 | * even if we're attaching all tasks in the thread group, we | |
2194 | * only need to check permissions on one of them. | |
2195 | */ | |
2196 | tcred = __task_cred(tsk); | |
2197 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && | |
2198 | !uid_eq(cred->euid, tcred->uid) && | |
2199 | !uid_eq(cred->euid, tcred->suid)) { | |
2200 | rcu_read_unlock(); | |
2201 | ret = -EACCES; | |
2202 | goto out_unlock_cgroup; | |
2203 | } | |
2204 | } else | |
2205 | tsk = current; | |
2206 | ||
2207 | if (threadgroup) | |
2208 | tsk = tsk->group_leader; | |
2209 | ||
2210 | /* | |
2211 | * Workqueue threads may acquire PF_THREAD_BOUND and become | |
2212 | * trapped in a cpuset, or RT worker may be born in a cgroup | |
2213 | * with no rt_runtime allocated. Just say no. | |
2214 | */ | |
2215 | if (tsk == kthreadd_task || (tsk->flags & PF_THREAD_BOUND)) { | |
2216 | ret = -EINVAL; | |
2217 | rcu_read_unlock(); | |
2218 | goto out_unlock_cgroup; | |
2219 | } | |
2220 | ||
2221 | get_task_struct(tsk); | |
2222 | rcu_read_unlock(); | |
2223 | ||
2224 | threadgroup_lock(tsk); | |
2225 | if (threadgroup) { | |
2226 | if (!thread_group_leader(tsk)) { | |
2227 | /* | |
2228 | * a race with de_thread from another thread's exec() | |
2229 | * may strip us of our leadership, if this happens, | |
2230 | * there is no choice but to throw this task away and | |
2231 | * try again; this is | |
2232 | * "double-double-toil-and-trouble-check locking". | |
2233 | */ | |
2234 | threadgroup_unlock(tsk); | |
2235 | put_task_struct(tsk); | |
2236 | goto retry_find_task; | |
2237 | } | |
2238 | ret = cgroup_attach_proc(cgrp, tsk); | |
2239 | } else | |
2240 | ret = cgroup_attach_task(cgrp, tsk); | |
2241 | threadgroup_unlock(tsk); | |
2242 | ||
2243 | put_task_struct(tsk); | |
2244 | out_unlock_cgroup: | |
2245 | cgroup_unlock(); | |
2246 | return ret; | |
2247 | } | |
2248 | ||
2249 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) | |
2250 | { | |
2251 | return attach_task_by_pid(cgrp, pid, false); | |
2252 | } | |
2253 | ||
2254 | static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) | |
2255 | { | |
2256 | return attach_task_by_pid(cgrp, tgid, true); | |
2257 | } | |
2258 | ||
2259 | /** | |
2260 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
2261 | * @cgrp: the cgroup to be checked for liveness | |
2262 | * | |
2263 | * On success, returns true; the lock should be later released with | |
2264 | * cgroup_unlock(). On failure returns false with no lock held. | |
2265 | */ | |
2266 | bool cgroup_lock_live_group(struct cgroup *cgrp) | |
2267 | { | |
2268 | mutex_lock(&cgroup_mutex); | |
2269 | if (cgroup_is_removed(cgrp)) { | |
2270 | mutex_unlock(&cgroup_mutex); | |
2271 | return false; | |
2272 | } | |
2273 | return true; | |
2274 | } | |
2275 | EXPORT_SYMBOL_GPL(cgroup_lock_live_group); | |
2276 | ||
2277 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, | |
2278 | const char *buffer) | |
2279 | { | |
2280 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); | |
2281 | if (strlen(buffer) >= PATH_MAX) | |
2282 | return -EINVAL; | |
2283 | if (!cgroup_lock_live_group(cgrp)) | |
2284 | return -ENODEV; | |
2285 | mutex_lock(&cgroup_root_mutex); | |
2286 | strcpy(cgrp->root->release_agent_path, buffer); | |
2287 | mutex_unlock(&cgroup_root_mutex); | |
2288 | cgroup_unlock(); | |
2289 | return 0; | |
2290 | } | |
2291 | ||
2292 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, | |
2293 | struct seq_file *seq) | |
2294 | { | |
2295 | if (!cgroup_lock_live_group(cgrp)) | |
2296 | return -ENODEV; | |
2297 | seq_puts(seq, cgrp->root->release_agent_path); | |
2298 | seq_putc(seq, '\n'); | |
2299 | cgroup_unlock(); | |
2300 | return 0; | |
2301 | } | |
2302 | ||
2303 | /* A buffer size big enough for numbers or short strings */ | |
2304 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
2305 | ||
2306 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, | |
2307 | struct file *file, | |
2308 | const char __user *userbuf, | |
2309 | size_t nbytes, loff_t *unused_ppos) | |
2310 | { | |
2311 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; | |
2312 | int retval = 0; | |
2313 | char *end; | |
2314 | ||
2315 | if (!nbytes) | |
2316 | return -EINVAL; | |
2317 | if (nbytes >= sizeof(buffer)) | |
2318 | return -E2BIG; | |
2319 | if (copy_from_user(buffer, userbuf, nbytes)) | |
2320 | return -EFAULT; | |
2321 | ||
2322 | buffer[nbytes] = 0; /* nul-terminate */ | |
2323 | if (cft->write_u64) { | |
2324 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); | |
2325 | if (*end) | |
2326 | return -EINVAL; | |
2327 | retval = cft->write_u64(cgrp, cft, val); | |
2328 | } else { | |
2329 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); | |
2330 | if (*end) | |
2331 | return -EINVAL; | |
2332 | retval = cft->write_s64(cgrp, cft, val); | |
2333 | } | |
2334 | if (!retval) | |
2335 | retval = nbytes; | |
2336 | return retval; | |
2337 | } | |
2338 | ||
2339 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, | |
2340 | struct file *file, | |
2341 | const char __user *userbuf, | |
2342 | size_t nbytes, loff_t *unused_ppos) | |
2343 | { | |
2344 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; | |
2345 | int retval = 0; | |
2346 | size_t max_bytes = cft->max_write_len; | |
2347 | char *buffer = local_buffer; | |
2348 | ||
2349 | if (!max_bytes) | |
2350 | max_bytes = sizeof(local_buffer) - 1; | |
2351 | if (nbytes >= max_bytes) | |
2352 | return -E2BIG; | |
2353 | /* Allocate a dynamic buffer if we need one */ | |
2354 | if (nbytes >= sizeof(local_buffer)) { | |
2355 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
2356 | if (buffer == NULL) | |
2357 | return -ENOMEM; | |
2358 | } | |
2359 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { | |
2360 | retval = -EFAULT; | |
2361 | goto out; | |
2362 | } | |
2363 | ||
2364 | buffer[nbytes] = 0; /* nul-terminate */ | |
2365 | retval = cft->write_string(cgrp, cft, strstrip(buffer)); | |
2366 | if (!retval) | |
2367 | retval = nbytes; | |
2368 | out: | |
2369 | if (buffer != local_buffer) | |
2370 | kfree(buffer); | |
2371 | return retval; | |
2372 | } | |
2373 | ||
2374 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, | |
2375 | size_t nbytes, loff_t *ppos) | |
2376 | { | |
2377 | struct cftype *cft = __d_cft(file->f_dentry); | |
2378 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); | |
2379 | ||
2380 | if (cgroup_is_removed(cgrp)) | |
2381 | return -ENODEV; | |
2382 | if (cft->write) | |
2383 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); | |
2384 | if (cft->write_u64 || cft->write_s64) | |
2385 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); | |
2386 | if (cft->write_string) | |
2387 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); | |
2388 | if (cft->trigger) { | |
2389 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); | |
2390 | return ret ? ret : nbytes; | |
2391 | } | |
2392 | return -EINVAL; | |
2393 | } | |
2394 | ||
2395 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, | |
2396 | struct file *file, | |
2397 | char __user *buf, size_t nbytes, | |
2398 | loff_t *ppos) | |
2399 | { | |
2400 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; | |
2401 | u64 val = cft->read_u64(cgrp, cft); | |
2402 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); | |
2403 | ||
2404 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2405 | } | |
2406 | ||
2407 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, | |
2408 | struct file *file, | |
2409 | char __user *buf, size_t nbytes, | |
2410 | loff_t *ppos) | |
2411 | { | |
2412 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; | |
2413 | s64 val = cft->read_s64(cgrp, cft); | |
2414 | int len = sprintf(tmp, "%lld\n", (long long) val); | |
2415 | ||
2416 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2417 | } | |
2418 | ||
2419 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, | |
2420 | size_t nbytes, loff_t *ppos) | |
2421 | { | |
2422 | struct cftype *cft = __d_cft(file->f_dentry); | |
2423 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); | |
2424 | ||
2425 | if (cgroup_is_removed(cgrp)) | |
2426 | return -ENODEV; | |
2427 | ||
2428 | if (cft->read) | |
2429 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); | |
2430 | if (cft->read_u64) | |
2431 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); | |
2432 | if (cft->read_s64) | |
2433 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); | |
2434 | return -EINVAL; | |
2435 | } | |
2436 | ||
2437 | /* | |
2438 | * seqfile ops/methods for returning structured data. Currently just | |
2439 | * supports string->u64 maps, but can be extended in future. | |
2440 | */ | |
2441 | ||
2442 | struct cgroup_seqfile_state { | |
2443 | struct cftype *cft; | |
2444 | struct cgroup *cgroup; | |
2445 | }; | |
2446 | ||
2447 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) | |
2448 | { | |
2449 | struct seq_file *sf = cb->state; | |
2450 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
2451 | } | |
2452 | ||
2453 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
2454 | { | |
2455 | struct cgroup_seqfile_state *state = m->private; | |
2456 | struct cftype *cft = state->cft; | |
2457 | if (cft->read_map) { | |
2458 | struct cgroup_map_cb cb = { | |
2459 | .fill = cgroup_map_add, | |
2460 | .state = m, | |
2461 | }; | |
2462 | return cft->read_map(state->cgroup, cft, &cb); | |
2463 | } | |
2464 | return cft->read_seq_string(state->cgroup, cft, m); | |
2465 | } | |
2466 | ||
2467 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) | |
2468 | { | |
2469 | struct seq_file *seq = file->private_data; | |
2470 | kfree(seq->private); | |
2471 | return single_release(inode, file); | |
2472 | } | |
2473 | ||
2474 | static const struct file_operations cgroup_seqfile_operations = { | |
2475 | .read = seq_read, | |
2476 | .write = cgroup_file_write, | |
2477 | .llseek = seq_lseek, | |
2478 | .release = cgroup_seqfile_release, | |
2479 | }; | |
2480 | ||
2481 | static int cgroup_file_open(struct inode *inode, struct file *file) | |
2482 | { | |
2483 | int err; | |
2484 | struct cftype *cft; | |
2485 | ||
2486 | err = generic_file_open(inode, file); | |
2487 | if (err) | |
2488 | return err; | |
2489 | cft = __d_cft(file->f_dentry); | |
2490 | ||
2491 | if (cft->read_map || cft->read_seq_string) { | |
2492 | struct cgroup_seqfile_state *state = | |
2493 | kzalloc(sizeof(*state), GFP_USER); | |
2494 | if (!state) | |
2495 | return -ENOMEM; | |
2496 | state->cft = cft; | |
2497 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); | |
2498 | file->f_op = &cgroup_seqfile_operations; | |
2499 | err = single_open(file, cgroup_seqfile_show, state); | |
2500 | if (err < 0) | |
2501 | kfree(state); | |
2502 | } else if (cft->open) | |
2503 | err = cft->open(inode, file); | |
2504 | else | |
2505 | err = 0; | |
2506 | ||
2507 | return err; | |
2508 | } | |
2509 | ||
2510 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
2511 | { | |
2512 | struct cftype *cft = __d_cft(file->f_dentry); | |
2513 | if (cft->release) | |
2514 | return cft->release(inode, file); | |
2515 | return 0; | |
2516 | } | |
2517 | ||
2518 | /* | |
2519 | * cgroup_rename - Only allow simple rename of directories in place. | |
2520 | */ | |
2521 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2522 | struct inode *new_dir, struct dentry *new_dentry) | |
2523 | { | |
2524 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) | |
2525 | return -ENOTDIR; | |
2526 | if (new_dentry->d_inode) | |
2527 | return -EEXIST; | |
2528 | if (old_dir != new_dir) | |
2529 | return -EIO; | |
2530 | return simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2531 | } | |
2532 | ||
2533 | static struct simple_xattrs *__d_xattrs(struct dentry *dentry) | |
2534 | { | |
2535 | if (S_ISDIR(dentry->d_inode->i_mode)) | |
2536 | return &__d_cgrp(dentry)->xattrs; | |
2537 | else | |
2538 | return &__d_cft(dentry)->xattrs; | |
2539 | } | |
2540 | ||
2541 | static inline int xattr_enabled(struct dentry *dentry) | |
2542 | { | |
2543 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; | |
2544 | return test_bit(ROOT_XATTR, &root->flags); | |
2545 | } | |
2546 | ||
2547 | static bool is_valid_xattr(const char *name) | |
2548 | { | |
2549 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || | |
2550 | !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) | |
2551 | return true; | |
2552 | return false; | |
2553 | } | |
2554 | ||
2555 | static int cgroup_setxattr(struct dentry *dentry, const char *name, | |
2556 | const void *val, size_t size, int flags) | |
2557 | { | |
2558 | if (!xattr_enabled(dentry)) | |
2559 | return -EOPNOTSUPP; | |
2560 | if (!is_valid_xattr(name)) | |
2561 | return -EINVAL; | |
2562 | return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); | |
2563 | } | |
2564 | ||
2565 | static int cgroup_removexattr(struct dentry *dentry, const char *name) | |
2566 | { | |
2567 | if (!xattr_enabled(dentry)) | |
2568 | return -EOPNOTSUPP; | |
2569 | if (!is_valid_xattr(name)) | |
2570 | return -EINVAL; | |
2571 | return simple_xattr_remove(__d_xattrs(dentry), name); | |
2572 | } | |
2573 | ||
2574 | static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, | |
2575 | void *buf, size_t size) | |
2576 | { | |
2577 | if (!xattr_enabled(dentry)) | |
2578 | return -EOPNOTSUPP; | |
2579 | if (!is_valid_xattr(name)) | |
2580 | return -EINVAL; | |
2581 | return simple_xattr_get(__d_xattrs(dentry), name, buf, size); | |
2582 | } | |
2583 | ||
2584 | static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) | |
2585 | { | |
2586 | if (!xattr_enabled(dentry)) | |
2587 | return -EOPNOTSUPP; | |
2588 | return simple_xattr_list(__d_xattrs(dentry), buf, size); | |
2589 | } | |
2590 | ||
2591 | static const struct file_operations cgroup_file_operations = { | |
2592 | .read = cgroup_file_read, | |
2593 | .write = cgroup_file_write, | |
2594 | .llseek = generic_file_llseek, | |
2595 | .open = cgroup_file_open, | |
2596 | .release = cgroup_file_release, | |
2597 | }; | |
2598 | ||
2599 | static const struct inode_operations cgroup_file_inode_operations = { | |
2600 | .setxattr = cgroup_setxattr, | |
2601 | .getxattr = cgroup_getxattr, | |
2602 | .listxattr = cgroup_listxattr, | |
2603 | .removexattr = cgroup_removexattr, | |
2604 | }; | |
2605 | ||
2606 | static const struct inode_operations cgroup_dir_inode_operations = { | |
2607 | .lookup = cgroup_lookup, | |
2608 | .mkdir = cgroup_mkdir, | |
2609 | .rmdir = cgroup_rmdir, | |
2610 | .rename = cgroup_rename, | |
2611 | .setxattr = cgroup_setxattr, | |
2612 | .getxattr = cgroup_getxattr, | |
2613 | .listxattr = cgroup_listxattr, | |
2614 | .removexattr = cgroup_removexattr, | |
2615 | }; | |
2616 | ||
2617 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) | |
2618 | { | |
2619 | if (dentry->d_name.len > NAME_MAX) | |
2620 | return ERR_PTR(-ENAMETOOLONG); | |
2621 | d_add(dentry, NULL); | |
2622 | return NULL; | |
2623 | } | |
2624 | ||
2625 | /* | |
2626 | * Check if a file is a control file | |
2627 | */ | |
2628 | static inline struct cftype *__file_cft(struct file *file) | |
2629 | { | |
2630 | if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations) | |
2631 | return ERR_PTR(-EINVAL); | |
2632 | return __d_cft(file->f_dentry); | |
2633 | } | |
2634 | ||
2635 | static int cgroup_create_file(struct dentry *dentry, umode_t mode, | |
2636 | struct super_block *sb) | |
2637 | { | |
2638 | struct inode *inode; | |
2639 | ||
2640 | if (!dentry) | |
2641 | return -ENOENT; | |
2642 | if (dentry->d_inode) | |
2643 | return -EEXIST; | |
2644 | ||
2645 | inode = cgroup_new_inode(mode, sb); | |
2646 | if (!inode) | |
2647 | return -ENOMEM; | |
2648 | ||
2649 | if (S_ISDIR(mode)) { | |
2650 | inode->i_op = &cgroup_dir_inode_operations; | |
2651 | inode->i_fop = &simple_dir_operations; | |
2652 | ||
2653 | /* start off with i_nlink == 2 (for "." entry) */ | |
2654 | inc_nlink(inode); | |
2655 | inc_nlink(dentry->d_parent->d_inode); | |
2656 | ||
2657 | /* start with the directory inode held, so that we can | |
2658 | * populate it without racing with another mkdir */ | |
2659 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); | |
2660 | } else if (S_ISREG(mode)) { | |
2661 | inode->i_size = 0; | |
2662 | inode->i_fop = &cgroup_file_operations; | |
2663 | inode->i_op = &cgroup_file_inode_operations; | |
2664 | } | |
2665 | d_instantiate(dentry, inode); | |
2666 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2667 | return 0; | |
2668 | } | |
2669 | ||
2670 | /** | |
2671 | * cgroup_file_mode - deduce file mode of a control file | |
2672 | * @cft: the control file in question | |
2673 | * | |
2674 | * returns cft->mode if ->mode is not 0 | |
2675 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
2676 | * returns S_IRUGO if it has only a read handler | |
2677 | * returns S_IWUSR if it has only a write hander | |
2678 | */ | |
2679 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
2680 | { | |
2681 | umode_t mode = 0; | |
2682 | ||
2683 | if (cft->mode) | |
2684 | return cft->mode; | |
2685 | ||
2686 | if (cft->read || cft->read_u64 || cft->read_s64 || | |
2687 | cft->read_map || cft->read_seq_string) | |
2688 | mode |= S_IRUGO; | |
2689 | ||
2690 | if (cft->write || cft->write_u64 || cft->write_s64 || | |
2691 | cft->write_string || cft->trigger) | |
2692 | mode |= S_IWUSR; | |
2693 | ||
2694 | return mode; | |
2695 | } | |
2696 | ||
2697 | static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, | |
2698 | struct cftype *cft) | |
2699 | { | |
2700 | struct dentry *dir = cgrp->dentry; | |
2701 | struct cgroup *parent = __d_cgrp(dir); | |
2702 | struct dentry *dentry; | |
2703 | struct cfent *cfe; | |
2704 | int error; | |
2705 | umode_t mode; | |
2706 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; | |
2707 | ||
2708 | simple_xattrs_init(&cft->xattrs); | |
2709 | ||
2710 | /* does @cft->flags tell us to skip creation on @cgrp? */ | |
2711 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) | |
2712 | return 0; | |
2713 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2714 | return 0; | |
2715 | ||
2716 | if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { | |
2717 | strcpy(name, subsys->name); | |
2718 | strcat(name, "."); | |
2719 | } | |
2720 | strcat(name, cft->name); | |
2721 | ||
2722 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); | |
2723 | ||
2724 | cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); | |
2725 | if (!cfe) | |
2726 | return -ENOMEM; | |
2727 | ||
2728 | dentry = lookup_one_len(name, dir, strlen(name)); | |
2729 | if (IS_ERR(dentry)) { | |
2730 | error = PTR_ERR(dentry); | |
2731 | goto out; | |
2732 | } | |
2733 | ||
2734 | mode = cgroup_file_mode(cft); | |
2735 | error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); | |
2736 | if (!error) { | |
2737 | cfe->type = (void *)cft; | |
2738 | cfe->dentry = dentry; | |
2739 | dentry->d_fsdata = cfe; | |
2740 | list_add_tail(&cfe->node, &parent->files); | |
2741 | cfe = NULL; | |
2742 | } | |
2743 | dput(dentry); | |
2744 | out: | |
2745 | kfree(cfe); | |
2746 | return error; | |
2747 | } | |
2748 | ||
2749 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, | |
2750 | struct cftype cfts[], bool is_add) | |
2751 | { | |
2752 | struct cftype *cft; | |
2753 | int err, ret = 0; | |
2754 | ||
2755 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
2756 | if (is_add) | |
2757 | err = cgroup_add_file(cgrp, subsys, cft); | |
2758 | else | |
2759 | err = cgroup_rm_file(cgrp, cft); | |
2760 | if (err) { | |
2761 | pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n", | |
2762 | is_add ? "add" : "remove", cft->name, err); | |
2763 | ret = err; | |
2764 | } | |
2765 | } | |
2766 | return ret; | |
2767 | } | |
2768 | ||
2769 | static DEFINE_MUTEX(cgroup_cft_mutex); | |
2770 | ||
2771 | static void cgroup_cfts_prepare(void) | |
2772 | __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex) | |
2773 | { | |
2774 | /* | |
2775 | * Thanks to the entanglement with vfs inode locking, we can't walk | |
2776 | * the existing cgroups under cgroup_mutex and create files. | |
2777 | * Instead, we increment reference on all cgroups and build list of | |
2778 | * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure | |
2779 | * exclusive access to the field. | |
2780 | */ | |
2781 | mutex_lock(&cgroup_cft_mutex); | |
2782 | mutex_lock(&cgroup_mutex); | |
2783 | } | |
2784 | ||
2785 | static void cgroup_cfts_commit(struct cgroup_subsys *ss, | |
2786 | struct cftype *cfts, bool is_add) | |
2787 | __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex) | |
2788 | { | |
2789 | LIST_HEAD(pending); | |
2790 | struct cgroup *cgrp, *n; | |
2791 | ||
2792 | /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ | |
2793 | if (cfts && ss->root != &rootnode) { | |
2794 | list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) { | |
2795 | dget(cgrp->dentry); | |
2796 | list_add_tail(&cgrp->cft_q_node, &pending); | |
2797 | } | |
2798 | } | |
2799 | ||
2800 | mutex_unlock(&cgroup_mutex); | |
2801 | ||
2802 | /* | |
2803 | * All new cgroups will see @cfts update on @ss->cftsets. Add/rm | |
2804 | * files for all cgroups which were created before. | |
2805 | */ | |
2806 | list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) { | |
2807 | struct inode *inode = cgrp->dentry->d_inode; | |
2808 | ||
2809 | mutex_lock(&inode->i_mutex); | |
2810 | mutex_lock(&cgroup_mutex); | |
2811 | if (!cgroup_is_removed(cgrp)) | |
2812 | cgroup_addrm_files(cgrp, ss, cfts, is_add); | |
2813 | mutex_unlock(&cgroup_mutex); | |
2814 | mutex_unlock(&inode->i_mutex); | |
2815 | ||
2816 | list_del_init(&cgrp->cft_q_node); | |
2817 | dput(cgrp->dentry); | |
2818 | } | |
2819 | ||
2820 | mutex_unlock(&cgroup_cft_mutex); | |
2821 | } | |
2822 | ||
2823 | /** | |
2824 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2825 | * @ss: target cgroup subsystem | |
2826 | * @cfts: zero-length name terminated array of cftypes | |
2827 | * | |
2828 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2829 | * existing cgroups to which @ss is attached and all future cgroups will | |
2830 | * have them too. This function can be called anytime whether @ss is | |
2831 | * attached or not. | |
2832 | * | |
2833 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2834 | * function currently returns 0 as long as @cfts registration is successful | |
2835 | * even if some file creation attempts on existing cgroups fail. | |
2836 | */ | |
2837 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) | |
2838 | { | |
2839 | struct cftype_set *set; | |
2840 | ||
2841 | set = kzalloc(sizeof(*set), GFP_KERNEL); | |
2842 | if (!set) | |
2843 | return -ENOMEM; | |
2844 | ||
2845 | cgroup_cfts_prepare(); | |
2846 | set->cfts = cfts; | |
2847 | list_add_tail(&set->node, &ss->cftsets); | |
2848 | cgroup_cfts_commit(ss, cfts, true); | |
2849 | ||
2850 | return 0; | |
2851 | } | |
2852 | EXPORT_SYMBOL_GPL(cgroup_add_cftypes); | |
2853 | ||
2854 | /** | |
2855 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
2856 | * @ss: target cgroup subsystem | |
2857 | * @cfts: zero-length name terminated array of cftypes | |
2858 | * | |
2859 | * Unregister @cfts from @ss. Files described by @cfts are removed from | |
2860 | * all existing cgroups to which @ss is attached and all future cgroups | |
2861 | * won't have them either. This function can be called anytime whether @ss | |
2862 | * is attached or not. | |
2863 | * | |
2864 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2865 | * registered with @ss. | |
2866 | */ | |
2867 | int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) | |
2868 | { | |
2869 | struct cftype_set *set; | |
2870 | ||
2871 | cgroup_cfts_prepare(); | |
2872 | ||
2873 | list_for_each_entry(set, &ss->cftsets, node) { | |
2874 | if (set->cfts == cfts) { | |
2875 | list_del_init(&set->node); | |
2876 | cgroup_cfts_commit(ss, cfts, false); | |
2877 | return 0; | |
2878 | } | |
2879 | } | |
2880 | ||
2881 | cgroup_cfts_commit(ss, NULL, false); | |
2882 | return -ENOENT; | |
2883 | } | |
2884 | ||
2885 | /** | |
2886 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2887 | * @cgrp: the cgroup in question | |
2888 | * | |
2889 | * Return the number of tasks in the cgroup. | |
2890 | */ | |
2891 | int cgroup_task_count(const struct cgroup *cgrp) | |
2892 | { | |
2893 | int count = 0; | |
2894 | struct cg_cgroup_link *link; | |
2895 | ||
2896 | read_lock(&css_set_lock); | |
2897 | list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { | |
2898 | count += atomic_read(&link->cg->refcount); | |
2899 | } | |
2900 | read_unlock(&css_set_lock); | |
2901 | return count; | |
2902 | } | |
2903 | ||
2904 | /* | |
2905 | * Advance a list_head iterator. The iterator should be positioned at | |
2906 | * the start of a css_set | |
2907 | */ | |
2908 | static void cgroup_advance_iter(struct cgroup *cgrp, | |
2909 | struct cgroup_iter *it) | |
2910 | { | |
2911 | struct list_head *l = it->cg_link; | |
2912 | struct cg_cgroup_link *link; | |
2913 | struct css_set *cg; | |
2914 | ||
2915 | /* Advance to the next non-empty css_set */ | |
2916 | do { | |
2917 | l = l->next; | |
2918 | if (l == &cgrp->css_sets) { | |
2919 | it->cg_link = NULL; | |
2920 | return; | |
2921 | } | |
2922 | link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); | |
2923 | cg = link->cg; | |
2924 | } while (list_empty(&cg->tasks)); | |
2925 | it->cg_link = l; | |
2926 | it->task = cg->tasks.next; | |
2927 | } | |
2928 | ||
2929 | /* | |
2930 | * To reduce the fork() overhead for systems that are not actually | |
2931 | * using their cgroups capability, we don't maintain the lists running | |
2932 | * through each css_set to its tasks until we see the list actually | |
2933 | * used - in other words after the first call to cgroup_iter_start(). | |
2934 | */ | |
2935 | static void cgroup_enable_task_cg_lists(void) | |
2936 | { | |
2937 | struct task_struct *p, *g; | |
2938 | write_lock(&css_set_lock); | |
2939 | use_task_css_set_links = 1; | |
2940 | /* | |
2941 | * We need tasklist_lock because RCU is not safe against | |
2942 | * while_each_thread(). Besides, a forking task that has passed | |
2943 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
2944 | * is not guaranteed to have its child immediately visible in the | |
2945 | * tasklist if we walk through it with RCU. | |
2946 | */ | |
2947 | read_lock(&tasklist_lock); | |
2948 | do_each_thread(g, p) { | |
2949 | task_lock(p); | |
2950 | /* | |
2951 | * We should check if the process is exiting, otherwise | |
2952 | * it will race with cgroup_exit() in that the list | |
2953 | * entry won't be deleted though the process has exited. | |
2954 | */ | |
2955 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
2956 | list_add(&p->cg_list, &p->cgroups->tasks); | |
2957 | task_unlock(p); | |
2958 | } while_each_thread(g, p); | |
2959 | read_unlock(&tasklist_lock); | |
2960 | write_unlock(&css_set_lock); | |
2961 | } | |
2962 | ||
2963 | /** | |
2964 | * cgroup_next_descendant_pre - find the next descendant for pre-order walk | |
2965 | * @pos: the current position (%NULL to initiate traversal) | |
2966 | * @cgroup: cgroup whose descendants to walk | |
2967 | * | |
2968 | * To be used by cgroup_for_each_descendant_pre(). Find the next | |
2969 | * descendant to visit for pre-order traversal of @cgroup's descendants. | |
2970 | */ | |
2971 | struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, | |
2972 | struct cgroup *cgroup) | |
2973 | { | |
2974 | struct cgroup *next; | |
2975 | ||
2976 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
2977 | ||
2978 | /* if first iteration, pretend we just visited @cgroup */ | |
2979 | if (!pos) { | |
2980 | if (list_empty(&cgroup->children)) | |
2981 | return NULL; | |
2982 | pos = cgroup; | |
2983 | } | |
2984 | ||
2985 | /* visit the first child if exists */ | |
2986 | next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling); | |
2987 | if (next) | |
2988 | return next; | |
2989 | ||
2990 | /* no child, visit my or the closest ancestor's next sibling */ | |
2991 | do { | |
2992 | next = list_entry_rcu(pos->sibling.next, struct cgroup, | |
2993 | sibling); | |
2994 | if (&next->sibling != &pos->parent->children) | |
2995 | return next; | |
2996 | ||
2997 | pos = pos->parent; | |
2998 | } while (pos != cgroup); | |
2999 | ||
3000 | return NULL; | |
3001 | } | |
3002 | EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre); | |
3003 | ||
3004 | static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) | |
3005 | { | |
3006 | struct cgroup *last; | |
3007 | ||
3008 | do { | |
3009 | last = pos; | |
3010 | pos = list_first_or_null_rcu(&pos->children, struct cgroup, | |
3011 | sibling); | |
3012 | } while (pos); | |
3013 | ||
3014 | return last; | |
3015 | } | |
3016 | ||
3017 | /** | |
3018 | * cgroup_next_descendant_post - find the next descendant for post-order walk | |
3019 | * @pos: the current position (%NULL to initiate traversal) | |
3020 | * @cgroup: cgroup whose descendants to walk | |
3021 | * | |
3022 | * To be used by cgroup_for_each_descendant_post(). Find the next | |
3023 | * descendant to visit for post-order traversal of @cgroup's descendants. | |
3024 | */ | |
3025 | struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, | |
3026 | struct cgroup *cgroup) | |
3027 | { | |
3028 | struct cgroup *next; | |
3029 | ||
3030 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3031 | ||
3032 | /* if first iteration, visit the leftmost descendant */ | |
3033 | if (!pos) { | |
3034 | next = cgroup_leftmost_descendant(cgroup); | |
3035 | return next != cgroup ? next : NULL; | |
3036 | } | |
3037 | ||
3038 | /* if there's an unvisited sibling, visit its leftmost descendant */ | |
3039 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); | |
3040 | if (&next->sibling != &pos->parent->children) | |
3041 | return cgroup_leftmost_descendant(next); | |
3042 | ||
3043 | /* no sibling left, visit parent */ | |
3044 | next = pos->parent; | |
3045 | return next != cgroup ? next : NULL; | |
3046 | } | |
3047 | EXPORT_SYMBOL_GPL(cgroup_next_descendant_post); | |
3048 | ||
3049 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) | |
3050 | __acquires(css_set_lock) | |
3051 | { | |
3052 | /* | |
3053 | * The first time anyone tries to iterate across a cgroup, | |
3054 | * we need to enable the list linking each css_set to its | |
3055 | * tasks, and fix up all existing tasks. | |
3056 | */ | |
3057 | if (!use_task_css_set_links) | |
3058 | cgroup_enable_task_cg_lists(); | |
3059 | ||
3060 | read_lock(&css_set_lock); | |
3061 | it->cg_link = &cgrp->css_sets; | |
3062 | cgroup_advance_iter(cgrp, it); | |
3063 | } | |
3064 | ||
3065 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, | |
3066 | struct cgroup_iter *it) | |
3067 | { | |
3068 | struct task_struct *res; | |
3069 | struct list_head *l = it->task; | |
3070 | struct cg_cgroup_link *link; | |
3071 | ||
3072 | /* If the iterator cg is NULL, we have no tasks */ | |
3073 | if (!it->cg_link) | |
3074 | return NULL; | |
3075 | res = list_entry(l, struct task_struct, cg_list); | |
3076 | /* Advance iterator to find next entry */ | |
3077 | l = l->next; | |
3078 | link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); | |
3079 | if (l == &link->cg->tasks) { | |
3080 | /* We reached the end of this task list - move on to | |
3081 | * the next cg_cgroup_link */ | |
3082 | cgroup_advance_iter(cgrp, it); | |
3083 | } else { | |
3084 | it->task = l; | |
3085 | } | |
3086 | return res; | |
3087 | } | |
3088 | ||
3089 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) | |
3090 | __releases(css_set_lock) | |
3091 | { | |
3092 | read_unlock(&css_set_lock); | |
3093 | } | |
3094 | ||
3095 | static inline int started_after_time(struct task_struct *t1, | |
3096 | struct timespec *time, | |
3097 | struct task_struct *t2) | |
3098 | { | |
3099 | int start_diff = timespec_compare(&t1->start_time, time); | |
3100 | if (start_diff > 0) { | |
3101 | return 1; | |
3102 | } else if (start_diff < 0) { | |
3103 | return 0; | |
3104 | } else { | |
3105 | /* | |
3106 | * Arbitrarily, if two processes started at the same | |
3107 | * time, we'll say that the lower pointer value | |
3108 | * started first. Note that t2 may have exited by now | |
3109 | * so this may not be a valid pointer any longer, but | |
3110 | * that's fine - it still serves to distinguish | |
3111 | * between two tasks started (effectively) simultaneously. | |
3112 | */ | |
3113 | return t1 > t2; | |
3114 | } | |
3115 | } | |
3116 | ||
3117 | /* | |
3118 | * This function is a callback from heap_insert() and is used to order | |
3119 | * the heap. | |
3120 | * In this case we order the heap in descending task start time. | |
3121 | */ | |
3122 | static inline int started_after(void *p1, void *p2) | |
3123 | { | |
3124 | struct task_struct *t1 = p1; | |
3125 | struct task_struct *t2 = p2; | |
3126 | return started_after_time(t1, &t2->start_time, t2); | |
3127 | } | |
3128 | ||
3129 | /** | |
3130 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
3131 | * @scan: struct cgroup_scanner containing arguments for the scan | |
3132 | * | |
3133 | * Arguments include pointers to callback functions test_task() and | |
3134 | * process_task(). | |
3135 | * Iterate through all the tasks in a cgroup, calling test_task() for each, | |
3136 | * and if it returns true, call process_task() for it also. | |
3137 | * The test_task pointer may be NULL, meaning always true (select all tasks). | |
3138 | * Effectively duplicates cgroup_iter_{start,next,end}() | |
3139 | * but does not lock css_set_lock for the call to process_task(). | |
3140 | * The struct cgroup_scanner may be embedded in any structure of the caller's | |
3141 | * creation. | |
3142 | * It is guaranteed that process_task() will act on every task that | |
3143 | * is a member of the cgroup for the duration of this call. This | |
3144 | * function may or may not call process_task() for tasks that exit | |
3145 | * or move to a different cgroup during the call, or are forked or | |
3146 | * move into the cgroup during the call. | |
3147 | * | |
3148 | * Note that test_task() may be called with locks held, and may in some | |
3149 | * situations be called multiple times for the same task, so it should | |
3150 | * be cheap. | |
3151 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been | |
3152 | * pre-allocated and will be used for heap operations (and its "gt" member will | |
3153 | * be overwritten), else a temporary heap will be used (allocation of which | |
3154 | * may cause this function to fail). | |
3155 | */ | |
3156 | int cgroup_scan_tasks(struct cgroup_scanner *scan) | |
3157 | { | |
3158 | int retval, i; | |
3159 | struct cgroup_iter it; | |
3160 | struct task_struct *p, *dropped; | |
3161 | /* Never dereference latest_task, since it's not refcounted */ | |
3162 | struct task_struct *latest_task = NULL; | |
3163 | struct ptr_heap tmp_heap; | |
3164 | struct ptr_heap *heap; | |
3165 | struct timespec latest_time = { 0, 0 }; | |
3166 | ||
3167 | if (scan->heap) { | |
3168 | /* The caller supplied our heap and pre-allocated its memory */ | |
3169 | heap = scan->heap; | |
3170 | heap->gt = &started_after; | |
3171 | } else { | |
3172 | /* We need to allocate our own heap memory */ | |
3173 | heap = &tmp_heap; | |
3174 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
3175 | if (retval) | |
3176 | /* cannot allocate the heap */ | |
3177 | return retval; | |
3178 | } | |
3179 | ||
3180 | again: | |
3181 | /* | |
3182 | * Scan tasks in the cgroup, using the scanner's "test_task" callback | |
3183 | * to determine which are of interest, and using the scanner's | |
3184 | * "process_task" callback to process any of them that need an update. | |
3185 | * Since we don't want to hold any locks during the task updates, | |
3186 | * gather tasks to be processed in a heap structure. | |
3187 | * The heap is sorted by descending task start time. | |
3188 | * If the statically-sized heap fills up, we overflow tasks that | |
3189 | * started later, and in future iterations only consider tasks that | |
3190 | * started after the latest task in the previous pass. This | |
3191 | * guarantees forward progress and that we don't miss any tasks. | |
3192 | */ | |
3193 | heap->size = 0; | |
3194 | cgroup_iter_start(scan->cg, &it); | |
3195 | while ((p = cgroup_iter_next(scan->cg, &it))) { | |
3196 | /* | |
3197 | * Only affect tasks that qualify per the caller's callback, | |
3198 | * if he provided one | |
3199 | */ | |
3200 | if (scan->test_task && !scan->test_task(p, scan)) | |
3201 | continue; | |
3202 | /* | |
3203 | * Only process tasks that started after the last task | |
3204 | * we processed | |
3205 | */ | |
3206 | if (!started_after_time(p, &latest_time, latest_task)) | |
3207 | continue; | |
3208 | dropped = heap_insert(heap, p); | |
3209 | if (dropped == NULL) { | |
3210 | /* | |
3211 | * The new task was inserted; the heap wasn't | |
3212 | * previously full | |
3213 | */ | |
3214 | get_task_struct(p); | |
3215 | } else if (dropped != p) { | |
3216 | /* | |
3217 | * The new task was inserted, and pushed out a | |
3218 | * different task | |
3219 | */ | |
3220 | get_task_struct(p); | |
3221 | put_task_struct(dropped); | |
3222 | } | |
3223 | /* | |
3224 | * Else the new task was newer than anything already in | |
3225 | * the heap and wasn't inserted | |
3226 | */ | |
3227 | } | |
3228 | cgroup_iter_end(scan->cg, &it); | |
3229 | ||
3230 | if (heap->size) { | |
3231 | for (i = 0; i < heap->size; i++) { | |
3232 | struct task_struct *q = heap->ptrs[i]; | |
3233 | if (i == 0) { | |
3234 | latest_time = q->start_time; | |
3235 | latest_task = q; | |
3236 | } | |
3237 | /* Process the task per the caller's callback */ | |
3238 | scan->process_task(q, scan); | |
3239 | put_task_struct(q); | |
3240 | } | |
3241 | /* | |
3242 | * If we had to process any tasks at all, scan again | |
3243 | * in case some of them were in the middle of forking | |
3244 | * children that didn't get processed. | |
3245 | * Not the most efficient way to do it, but it avoids | |
3246 | * having to take callback_mutex in the fork path | |
3247 | */ | |
3248 | goto again; | |
3249 | } | |
3250 | if (heap == &tmp_heap) | |
3251 | heap_free(&tmp_heap); | |
3252 | return 0; | |
3253 | } | |
3254 | ||
3255 | /* | |
3256 | * Stuff for reading the 'tasks'/'procs' files. | |
3257 | * | |
3258 | * Reading this file can return large amounts of data if a cgroup has | |
3259 | * *lots* of attached tasks. So it may need several calls to read(), | |
3260 | * but we cannot guarantee that the information we produce is correct | |
3261 | * unless we produce it entirely atomically. | |
3262 | * | |
3263 | */ | |
3264 | ||
3265 | /* which pidlist file are we talking about? */ | |
3266 | enum cgroup_filetype { | |
3267 | CGROUP_FILE_PROCS, | |
3268 | CGROUP_FILE_TASKS, | |
3269 | }; | |
3270 | ||
3271 | /* | |
3272 | * A pidlist is a list of pids that virtually represents the contents of one | |
3273 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3274 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3275 | * to the cgroup. | |
3276 | */ | |
3277 | struct cgroup_pidlist { | |
3278 | /* | |
3279 | * used to find which pidlist is wanted. doesn't change as long as | |
3280 | * this particular list stays in the list. | |
3281 | */ | |
3282 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3283 | /* array of xids */ | |
3284 | pid_t *list; | |
3285 | /* how many elements the above list has */ | |
3286 | int length; | |
3287 | /* how many files are using the current array */ | |
3288 | int use_count; | |
3289 | /* each of these stored in a list by its cgroup */ | |
3290 | struct list_head links; | |
3291 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3292 | struct cgroup *owner; | |
3293 | /* protects the other fields */ | |
3294 | struct rw_semaphore mutex; | |
3295 | }; | |
3296 | ||
3297 | /* | |
3298 | * The following two functions "fix" the issue where there are more pids | |
3299 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3300 | * TODO: replace with a kernel-wide solution to this problem | |
3301 | */ | |
3302 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3303 | static void *pidlist_allocate(int count) | |
3304 | { | |
3305 | if (PIDLIST_TOO_LARGE(count)) | |
3306 | return vmalloc(count * sizeof(pid_t)); | |
3307 | else | |
3308 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3309 | } | |
3310 | static void pidlist_free(void *p) | |
3311 | { | |
3312 | if (is_vmalloc_addr(p)) | |
3313 | vfree(p); | |
3314 | else | |
3315 | kfree(p); | |
3316 | } | |
3317 | static void *pidlist_resize(void *p, int newcount) | |
3318 | { | |
3319 | void *newlist; | |
3320 | /* note: if new alloc fails, old p will still be valid either way */ | |
3321 | if (is_vmalloc_addr(p)) { | |
3322 | newlist = vmalloc(newcount * sizeof(pid_t)); | |
3323 | if (!newlist) | |
3324 | return NULL; | |
3325 | memcpy(newlist, p, newcount * sizeof(pid_t)); | |
3326 | vfree(p); | |
3327 | } else { | |
3328 | newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); | |
3329 | } | |
3330 | return newlist; | |
3331 | } | |
3332 | ||
3333 | /* | |
3334 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries | |
3335 | * If the new stripped list is sufficiently smaller and there's enough memory | |
3336 | * to allocate a new buffer, will let go of the unneeded memory. Returns the | |
3337 | * number of unique elements. | |
3338 | */ | |
3339 | /* is the size difference enough that we should re-allocate the array? */ | |
3340 | #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) | |
3341 | static int pidlist_uniq(pid_t **p, int length) | |
3342 | { | |
3343 | int src, dest = 1; | |
3344 | pid_t *list = *p; | |
3345 | pid_t *newlist; | |
3346 | ||
3347 | /* | |
3348 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3349 | * edge cases first; no work needs to be done for either | |
3350 | */ | |
3351 | if (length == 0 || length == 1) | |
3352 | return length; | |
3353 | /* src and dest walk down the list; dest counts unique elements */ | |
3354 | for (src = 1; src < length; src++) { | |
3355 | /* find next unique element */ | |
3356 | while (list[src] == list[src-1]) { | |
3357 | src++; | |
3358 | if (src == length) | |
3359 | goto after; | |
3360 | } | |
3361 | /* dest always points to where the next unique element goes */ | |
3362 | list[dest] = list[src]; | |
3363 | dest++; | |
3364 | } | |
3365 | after: | |
3366 | /* | |
3367 | * if the length difference is large enough, we want to allocate a | |
3368 | * smaller buffer to save memory. if this fails due to out of memory, | |
3369 | * we'll just stay with what we've got. | |
3370 | */ | |
3371 | if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { | |
3372 | newlist = pidlist_resize(list, dest); | |
3373 | if (newlist) | |
3374 | *p = newlist; | |
3375 | } | |
3376 | return dest; | |
3377 | } | |
3378 | ||
3379 | static int cmppid(const void *a, const void *b) | |
3380 | { | |
3381 | return *(pid_t *)a - *(pid_t *)b; | |
3382 | } | |
3383 | ||
3384 | /* | |
3385 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3386 | * returns with the lock on that pidlist already held, and takes care | |
3387 | * of the use count, or returns NULL with no locks held if we're out of | |
3388 | * memory. | |
3389 | */ | |
3390 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, | |
3391 | enum cgroup_filetype type) | |
3392 | { | |
3393 | struct cgroup_pidlist *l; | |
3394 | /* don't need task_nsproxy() if we're looking at ourself */ | |
3395 | struct pid_namespace *ns = current->nsproxy->pid_ns; | |
3396 | ||
3397 | /* | |
3398 | * We can't drop the pidlist_mutex before taking the l->mutex in case | |
3399 | * the last ref-holder is trying to remove l from the list at the same | |
3400 | * time. Holding the pidlist_mutex precludes somebody taking whichever | |
3401 | * list we find out from under us - compare release_pid_array(). | |
3402 | */ | |
3403 | mutex_lock(&cgrp->pidlist_mutex); | |
3404 | list_for_each_entry(l, &cgrp->pidlists, links) { | |
3405 | if (l->key.type == type && l->key.ns == ns) { | |
3406 | /* make sure l doesn't vanish out from under us */ | |
3407 | down_write(&l->mutex); | |
3408 | mutex_unlock(&cgrp->pidlist_mutex); | |
3409 | return l; | |
3410 | } | |
3411 | } | |
3412 | /* entry not found; create a new one */ | |
3413 | l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); | |
3414 | if (!l) { | |
3415 | mutex_unlock(&cgrp->pidlist_mutex); | |
3416 | return l; | |
3417 | } | |
3418 | init_rwsem(&l->mutex); | |
3419 | down_write(&l->mutex); | |
3420 | l->key.type = type; | |
3421 | l->key.ns = get_pid_ns(ns); | |
3422 | l->use_count = 0; /* don't increment here */ | |
3423 | l->list = NULL; | |
3424 | l->owner = cgrp; | |
3425 | list_add(&l->links, &cgrp->pidlists); | |
3426 | mutex_unlock(&cgrp->pidlist_mutex); | |
3427 | return l; | |
3428 | } | |
3429 | ||
3430 | /* | |
3431 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3432 | */ | |
3433 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, | |
3434 | struct cgroup_pidlist **lp) | |
3435 | { | |
3436 | pid_t *array; | |
3437 | int length; | |
3438 | int pid, n = 0; /* used for populating the array */ | |
3439 | struct cgroup_iter it; | |
3440 | struct task_struct *tsk; | |
3441 | struct cgroup_pidlist *l; | |
3442 | ||
3443 | /* | |
3444 | * If cgroup gets more users after we read count, we won't have | |
3445 | * enough space - tough. This race is indistinguishable to the | |
3446 | * caller from the case that the additional cgroup users didn't | |
3447 | * show up until sometime later on. | |
3448 | */ | |
3449 | length = cgroup_task_count(cgrp); | |
3450 | array = pidlist_allocate(length); | |
3451 | if (!array) | |
3452 | return -ENOMEM; | |
3453 | /* now, populate the array */ | |
3454 | cgroup_iter_start(cgrp, &it); | |
3455 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
3456 | if (unlikely(n == length)) | |
3457 | break; | |
3458 | /* get tgid or pid for procs or tasks file respectively */ | |
3459 | if (type == CGROUP_FILE_PROCS) | |
3460 | pid = task_tgid_vnr(tsk); | |
3461 | else | |
3462 | pid = task_pid_vnr(tsk); | |
3463 | if (pid > 0) /* make sure to only use valid results */ | |
3464 | array[n++] = pid; | |
3465 | } | |
3466 | cgroup_iter_end(cgrp, &it); | |
3467 | length = n; | |
3468 | /* now sort & (if procs) strip out duplicates */ | |
3469 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
3470 | if (type == CGROUP_FILE_PROCS) | |
3471 | length = pidlist_uniq(&array, length); | |
3472 | l = cgroup_pidlist_find(cgrp, type); | |
3473 | if (!l) { | |
3474 | pidlist_free(array); | |
3475 | return -ENOMEM; | |
3476 | } | |
3477 | /* store array, freeing old if necessary - lock already held */ | |
3478 | pidlist_free(l->list); | |
3479 | l->list = array; | |
3480 | l->length = length; | |
3481 | l->use_count++; | |
3482 | up_write(&l->mutex); | |
3483 | *lp = l; | |
3484 | return 0; | |
3485 | } | |
3486 | ||
3487 | /** | |
3488 | * cgroupstats_build - build and fill cgroupstats | |
3489 | * @stats: cgroupstats to fill information into | |
3490 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3491 | * been requested. | |
3492 | * | |
3493 | * Build and fill cgroupstats so that taskstats can export it to user | |
3494 | * space. | |
3495 | */ | |
3496 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3497 | { | |
3498 | int ret = -EINVAL; | |
3499 | struct cgroup *cgrp; | |
3500 | struct cgroup_iter it; | |
3501 | struct task_struct *tsk; | |
3502 | ||
3503 | /* | |
3504 | * Validate dentry by checking the superblock operations, | |
3505 | * and make sure it's a directory. | |
3506 | */ | |
3507 | if (dentry->d_sb->s_op != &cgroup_ops || | |
3508 | !S_ISDIR(dentry->d_inode->i_mode)) | |
3509 | goto err; | |
3510 | ||
3511 | ret = 0; | |
3512 | cgrp = dentry->d_fsdata; | |
3513 | ||
3514 | cgroup_iter_start(cgrp, &it); | |
3515 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
3516 | switch (tsk->state) { | |
3517 | case TASK_RUNNING: | |
3518 | stats->nr_running++; | |
3519 | break; | |
3520 | case TASK_INTERRUPTIBLE: | |
3521 | stats->nr_sleeping++; | |
3522 | break; | |
3523 | case TASK_UNINTERRUPTIBLE: | |
3524 | stats->nr_uninterruptible++; | |
3525 | break; | |
3526 | case TASK_STOPPED: | |
3527 | stats->nr_stopped++; | |
3528 | break; | |
3529 | default: | |
3530 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3531 | stats->nr_io_wait++; | |
3532 | break; | |
3533 | } | |
3534 | } | |
3535 | cgroup_iter_end(cgrp, &it); | |
3536 | ||
3537 | err: | |
3538 | return ret; | |
3539 | } | |
3540 | ||
3541 | ||
3542 | /* | |
3543 | * seq_file methods for the tasks/procs files. The seq_file position is the | |
3544 | * next pid to display; the seq_file iterator is a pointer to the pid | |
3545 | * in the cgroup->l->list array. | |
3546 | */ | |
3547 | ||
3548 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) | |
3549 | { | |
3550 | /* | |
3551 | * Initially we receive a position value that corresponds to | |
3552 | * one more than the last pid shown (or 0 on the first call or | |
3553 | * after a seek to the start). Use a binary-search to find the | |
3554 | * next pid to display, if any | |
3555 | */ | |
3556 | struct cgroup_pidlist *l = s->private; | |
3557 | int index = 0, pid = *pos; | |
3558 | int *iter; | |
3559 | ||
3560 | down_read(&l->mutex); | |
3561 | if (pid) { | |
3562 | int end = l->length; | |
3563 | ||
3564 | while (index < end) { | |
3565 | int mid = (index + end) / 2; | |
3566 | if (l->list[mid] == pid) { | |
3567 | index = mid; | |
3568 | break; | |
3569 | } else if (l->list[mid] <= pid) | |
3570 | index = mid + 1; | |
3571 | else | |
3572 | end = mid; | |
3573 | } | |
3574 | } | |
3575 | /* If we're off the end of the array, we're done */ | |
3576 | if (index >= l->length) | |
3577 | return NULL; | |
3578 | /* Update the abstract position to be the actual pid that we found */ | |
3579 | iter = l->list + index; | |
3580 | *pos = *iter; | |
3581 | return iter; | |
3582 | } | |
3583 | ||
3584 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) | |
3585 | { | |
3586 | struct cgroup_pidlist *l = s->private; | |
3587 | up_read(&l->mutex); | |
3588 | } | |
3589 | ||
3590 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) | |
3591 | { | |
3592 | struct cgroup_pidlist *l = s->private; | |
3593 | pid_t *p = v; | |
3594 | pid_t *end = l->list + l->length; | |
3595 | /* | |
3596 | * Advance to the next pid in the array. If this goes off the | |
3597 | * end, we're done | |
3598 | */ | |
3599 | p++; | |
3600 | if (p >= end) { | |
3601 | return NULL; | |
3602 | } else { | |
3603 | *pos = *p; | |
3604 | return p; | |
3605 | } | |
3606 | } | |
3607 | ||
3608 | static int cgroup_pidlist_show(struct seq_file *s, void *v) | |
3609 | { | |
3610 | return seq_printf(s, "%d\n", *(int *)v); | |
3611 | } | |
3612 | ||
3613 | /* | |
3614 | * seq_operations functions for iterating on pidlists through seq_file - | |
3615 | * independent of whether it's tasks or procs | |
3616 | */ | |
3617 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3618 | .start = cgroup_pidlist_start, | |
3619 | .stop = cgroup_pidlist_stop, | |
3620 | .next = cgroup_pidlist_next, | |
3621 | .show = cgroup_pidlist_show, | |
3622 | }; | |
3623 | ||
3624 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) | |
3625 | { | |
3626 | /* | |
3627 | * the case where we're the last user of this particular pidlist will | |
3628 | * have us remove it from the cgroup's list, which entails taking the | |
3629 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> | |
3630 | * pidlist_mutex, we have to take pidlist_mutex first. | |
3631 | */ | |
3632 | mutex_lock(&l->owner->pidlist_mutex); | |
3633 | down_write(&l->mutex); | |
3634 | BUG_ON(!l->use_count); | |
3635 | if (!--l->use_count) { | |
3636 | /* we're the last user if refcount is 0; remove and free */ | |
3637 | list_del(&l->links); | |
3638 | mutex_unlock(&l->owner->pidlist_mutex); | |
3639 | pidlist_free(l->list); | |
3640 | put_pid_ns(l->key.ns); | |
3641 | up_write(&l->mutex); | |
3642 | kfree(l); | |
3643 | return; | |
3644 | } | |
3645 | mutex_unlock(&l->owner->pidlist_mutex); | |
3646 | up_write(&l->mutex); | |
3647 | } | |
3648 | ||
3649 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) | |
3650 | { | |
3651 | struct cgroup_pidlist *l; | |
3652 | if (!(file->f_mode & FMODE_READ)) | |
3653 | return 0; | |
3654 | /* | |
3655 | * the seq_file will only be initialized if the file was opened for | |
3656 | * reading; hence we check if it's not null only in that case. | |
3657 | */ | |
3658 | l = ((struct seq_file *)file->private_data)->private; | |
3659 | cgroup_release_pid_array(l); | |
3660 | return seq_release(inode, file); | |
3661 | } | |
3662 | ||
3663 | static const struct file_operations cgroup_pidlist_operations = { | |
3664 | .read = seq_read, | |
3665 | .llseek = seq_lseek, | |
3666 | .write = cgroup_file_write, | |
3667 | .release = cgroup_pidlist_release, | |
3668 | }; | |
3669 | ||
3670 | /* | |
3671 | * The following functions handle opens on a file that displays a pidlist | |
3672 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's | |
3673 | * in the cgroup. | |
3674 | */ | |
3675 | /* helper function for the two below it */ | |
3676 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) | |
3677 | { | |
3678 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); | |
3679 | struct cgroup_pidlist *l; | |
3680 | int retval; | |
3681 | ||
3682 | /* Nothing to do for write-only files */ | |
3683 | if (!(file->f_mode & FMODE_READ)) | |
3684 | return 0; | |
3685 | ||
3686 | /* have the array populated */ | |
3687 | retval = pidlist_array_load(cgrp, type, &l); | |
3688 | if (retval) | |
3689 | return retval; | |
3690 | /* configure file information */ | |
3691 | file->f_op = &cgroup_pidlist_operations; | |
3692 | ||
3693 | retval = seq_open(file, &cgroup_pidlist_seq_operations); | |
3694 | if (retval) { | |
3695 | cgroup_release_pid_array(l); | |
3696 | return retval; | |
3697 | } | |
3698 | ((struct seq_file *)file->private_data)->private = l; | |
3699 | return 0; | |
3700 | } | |
3701 | static int cgroup_tasks_open(struct inode *unused, struct file *file) | |
3702 | { | |
3703 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); | |
3704 | } | |
3705 | static int cgroup_procs_open(struct inode *unused, struct file *file) | |
3706 | { | |
3707 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); | |
3708 | } | |
3709 | ||
3710 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, | |
3711 | struct cftype *cft) | |
3712 | { | |
3713 | return notify_on_release(cgrp); | |
3714 | } | |
3715 | ||
3716 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, | |
3717 | struct cftype *cft, | |
3718 | u64 val) | |
3719 | { | |
3720 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); | |
3721 | if (val) | |
3722 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3723 | else | |
3724 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3725 | return 0; | |
3726 | } | |
3727 | ||
3728 | /* | |
3729 | * Unregister event and free resources. | |
3730 | * | |
3731 | * Gets called from workqueue. | |
3732 | */ | |
3733 | static void cgroup_event_remove(struct work_struct *work) | |
3734 | { | |
3735 | struct cgroup_event *event = container_of(work, struct cgroup_event, | |
3736 | remove); | |
3737 | struct cgroup *cgrp = event->cgrp; | |
3738 | ||
3739 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); | |
3740 | ||
3741 | eventfd_ctx_put(event->eventfd); | |
3742 | kfree(event); | |
3743 | dput(cgrp->dentry); | |
3744 | } | |
3745 | ||
3746 | /* | |
3747 | * Gets called on POLLHUP on eventfd when user closes it. | |
3748 | * | |
3749 | * Called with wqh->lock held and interrupts disabled. | |
3750 | */ | |
3751 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, | |
3752 | int sync, void *key) | |
3753 | { | |
3754 | struct cgroup_event *event = container_of(wait, | |
3755 | struct cgroup_event, wait); | |
3756 | struct cgroup *cgrp = event->cgrp; | |
3757 | unsigned long flags = (unsigned long)key; | |
3758 | ||
3759 | if (flags & POLLHUP) { | |
3760 | __remove_wait_queue(event->wqh, &event->wait); | |
3761 | spin_lock(&cgrp->event_list_lock); | |
3762 | list_del(&event->list); | |
3763 | spin_unlock(&cgrp->event_list_lock); | |
3764 | /* | |
3765 | * We are in atomic context, but cgroup_event_remove() may | |
3766 | * sleep, so we have to call it in workqueue. | |
3767 | */ | |
3768 | schedule_work(&event->remove); | |
3769 | } | |
3770 | ||
3771 | return 0; | |
3772 | } | |
3773 | ||
3774 | static void cgroup_event_ptable_queue_proc(struct file *file, | |
3775 | wait_queue_head_t *wqh, poll_table *pt) | |
3776 | { | |
3777 | struct cgroup_event *event = container_of(pt, | |
3778 | struct cgroup_event, pt); | |
3779 | ||
3780 | event->wqh = wqh; | |
3781 | add_wait_queue(wqh, &event->wait); | |
3782 | } | |
3783 | ||
3784 | /* | |
3785 | * Parse input and register new cgroup event handler. | |
3786 | * | |
3787 | * Input must be in format '<event_fd> <control_fd> <args>'. | |
3788 | * Interpretation of args is defined by control file implementation. | |
3789 | */ | |
3790 | static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, | |
3791 | const char *buffer) | |
3792 | { | |
3793 | struct cgroup_event *event = NULL; | |
3794 | unsigned int efd, cfd; | |
3795 | struct file *efile = NULL; | |
3796 | struct file *cfile = NULL; | |
3797 | char *endp; | |
3798 | int ret; | |
3799 | ||
3800 | efd = simple_strtoul(buffer, &endp, 10); | |
3801 | if (*endp != ' ') | |
3802 | return -EINVAL; | |
3803 | buffer = endp + 1; | |
3804 | ||
3805 | cfd = simple_strtoul(buffer, &endp, 10); | |
3806 | if ((*endp != ' ') && (*endp != '\0')) | |
3807 | return -EINVAL; | |
3808 | buffer = endp + 1; | |
3809 | ||
3810 | event = kzalloc(sizeof(*event), GFP_KERNEL); | |
3811 | if (!event) | |
3812 | return -ENOMEM; | |
3813 | event->cgrp = cgrp; | |
3814 | INIT_LIST_HEAD(&event->list); | |
3815 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); | |
3816 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); | |
3817 | INIT_WORK(&event->remove, cgroup_event_remove); | |
3818 | ||
3819 | efile = eventfd_fget(efd); | |
3820 | if (IS_ERR(efile)) { | |
3821 | ret = PTR_ERR(efile); | |
3822 | goto fail; | |
3823 | } | |
3824 | ||
3825 | event->eventfd = eventfd_ctx_fileget(efile); | |
3826 | if (IS_ERR(event->eventfd)) { | |
3827 | ret = PTR_ERR(event->eventfd); | |
3828 | goto fail; | |
3829 | } | |
3830 | ||
3831 | cfile = fget(cfd); | |
3832 | if (!cfile) { | |
3833 | ret = -EBADF; | |
3834 | goto fail; | |
3835 | } | |
3836 | ||
3837 | /* the process need read permission on control file */ | |
3838 | /* AV: shouldn't we check that it's been opened for read instead? */ | |
3839 | ret = inode_permission(cfile->f_path.dentry->d_inode, MAY_READ); | |
3840 | if (ret < 0) | |
3841 | goto fail; | |
3842 | ||
3843 | event->cft = __file_cft(cfile); | |
3844 | if (IS_ERR(event->cft)) { | |
3845 | ret = PTR_ERR(event->cft); | |
3846 | goto fail; | |
3847 | } | |
3848 | ||
3849 | if (!event->cft->register_event || !event->cft->unregister_event) { | |
3850 | ret = -EINVAL; | |
3851 | goto fail; | |
3852 | } | |
3853 | ||
3854 | ret = event->cft->register_event(cgrp, event->cft, | |
3855 | event->eventfd, buffer); | |
3856 | if (ret) | |
3857 | goto fail; | |
3858 | ||
3859 | if (efile->f_op->poll(efile, &event->pt) & POLLHUP) { | |
3860 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); | |
3861 | ret = 0; | |
3862 | goto fail; | |
3863 | } | |
3864 | ||
3865 | /* | |
3866 | * Events should be removed after rmdir of cgroup directory, but before | |
3867 | * destroying subsystem state objects. Let's take reference to cgroup | |
3868 | * directory dentry to do that. | |
3869 | */ | |
3870 | dget(cgrp->dentry); | |
3871 | ||
3872 | spin_lock(&cgrp->event_list_lock); | |
3873 | list_add(&event->list, &cgrp->event_list); | |
3874 | spin_unlock(&cgrp->event_list_lock); | |
3875 | ||
3876 | fput(cfile); | |
3877 | fput(efile); | |
3878 | ||
3879 | return 0; | |
3880 | ||
3881 | fail: | |
3882 | if (cfile) | |
3883 | fput(cfile); | |
3884 | ||
3885 | if (event && event->eventfd && !IS_ERR(event->eventfd)) | |
3886 | eventfd_ctx_put(event->eventfd); | |
3887 | ||
3888 | if (!IS_ERR_OR_NULL(efile)) | |
3889 | fput(efile); | |
3890 | ||
3891 | kfree(event); | |
3892 | ||
3893 | return ret; | |
3894 | } | |
3895 | ||
3896 | static u64 cgroup_clone_children_read(struct cgroup *cgrp, | |
3897 | struct cftype *cft) | |
3898 | { | |
3899 | return clone_children(cgrp); | |
3900 | } | |
3901 | ||
3902 | static int cgroup_clone_children_write(struct cgroup *cgrp, | |
3903 | struct cftype *cft, | |
3904 | u64 val) | |
3905 | { | |
3906 | if (val) | |
3907 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3908 | else | |
3909 | clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
3910 | return 0; | |
3911 | } | |
3912 | ||
3913 | /* | |
3914 | * for the common functions, 'private' gives the type of file | |
3915 | */ | |
3916 | /* for hysterical raisins, we can't put this on the older files */ | |
3917 | #define CGROUP_FILE_GENERIC_PREFIX "cgroup." | |
3918 | static struct cftype files[] = { | |
3919 | { | |
3920 | .name = "tasks", | |
3921 | .open = cgroup_tasks_open, | |
3922 | .write_u64 = cgroup_tasks_write, | |
3923 | .release = cgroup_pidlist_release, | |
3924 | .mode = S_IRUGO | S_IWUSR, | |
3925 | }, | |
3926 | { | |
3927 | .name = CGROUP_FILE_GENERIC_PREFIX "procs", | |
3928 | .open = cgroup_procs_open, | |
3929 | .write_u64 = cgroup_procs_write, | |
3930 | .release = cgroup_pidlist_release, | |
3931 | .mode = S_IRUGO | S_IWUSR, | |
3932 | }, | |
3933 | { | |
3934 | .name = "notify_on_release", | |
3935 | .read_u64 = cgroup_read_notify_on_release, | |
3936 | .write_u64 = cgroup_write_notify_on_release, | |
3937 | }, | |
3938 | { | |
3939 | .name = CGROUP_FILE_GENERIC_PREFIX "event_control", | |
3940 | .write_string = cgroup_write_event_control, | |
3941 | .mode = S_IWUGO, | |
3942 | }, | |
3943 | { | |
3944 | .name = "cgroup.clone_children", | |
3945 | .read_u64 = cgroup_clone_children_read, | |
3946 | .write_u64 = cgroup_clone_children_write, | |
3947 | }, | |
3948 | { | |
3949 | .name = "release_agent", | |
3950 | .flags = CFTYPE_ONLY_ON_ROOT, | |
3951 | .read_seq_string = cgroup_release_agent_show, | |
3952 | .write_string = cgroup_release_agent_write, | |
3953 | .max_write_len = PATH_MAX, | |
3954 | }, | |
3955 | { } /* terminate */ | |
3956 | }; | |
3957 | ||
3958 | /** | |
3959 | * cgroup_populate_dir - selectively creation of files in a directory | |
3960 | * @cgrp: target cgroup | |
3961 | * @base_files: true if the base files should be added | |
3962 | * @subsys_mask: mask of the subsystem ids whose files should be added | |
3963 | */ | |
3964 | static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, | |
3965 | unsigned long subsys_mask) | |
3966 | { | |
3967 | int err; | |
3968 | struct cgroup_subsys *ss; | |
3969 | ||
3970 | if (base_files) { | |
3971 | err = cgroup_addrm_files(cgrp, NULL, files, true); | |
3972 | if (err < 0) | |
3973 | return err; | |
3974 | } | |
3975 | ||
3976 | /* process cftsets of each subsystem */ | |
3977 | for_each_subsys(cgrp->root, ss) { | |
3978 | struct cftype_set *set; | |
3979 | if (!test_bit(ss->subsys_id, &subsys_mask)) | |
3980 | continue; | |
3981 | ||
3982 | list_for_each_entry(set, &ss->cftsets, node) | |
3983 | cgroup_addrm_files(cgrp, ss, set->cfts, true); | |
3984 | } | |
3985 | ||
3986 | /* This cgroup is ready now */ | |
3987 | for_each_subsys(cgrp->root, ss) { | |
3988 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
3989 | /* | |
3990 | * Update id->css pointer and make this css visible from | |
3991 | * CSS ID functions. This pointer will be dereferened | |
3992 | * from RCU-read-side without locks. | |
3993 | */ | |
3994 | if (css->id) | |
3995 | rcu_assign_pointer(css->id->css, css); | |
3996 | } | |
3997 | ||
3998 | return 0; | |
3999 | } | |
4000 | ||
4001 | static void css_dput_fn(struct work_struct *work) | |
4002 | { | |
4003 | struct cgroup_subsys_state *css = | |
4004 | container_of(work, struct cgroup_subsys_state, dput_work); | |
4005 | struct dentry *dentry = css->cgroup->dentry; | |
4006 | struct super_block *sb = dentry->d_sb; | |
4007 | ||
4008 | atomic_inc(&sb->s_active); | |
4009 | dput(dentry); | |
4010 | deactivate_super(sb); | |
4011 | } | |
4012 | ||
4013 | static void init_cgroup_css(struct cgroup_subsys_state *css, | |
4014 | struct cgroup_subsys *ss, | |
4015 | struct cgroup *cgrp) | |
4016 | { | |
4017 | css->cgroup = cgrp; | |
4018 | atomic_set(&css->refcnt, 1); | |
4019 | css->flags = 0; | |
4020 | css->id = NULL; | |
4021 | if (cgrp == dummytop) | |
4022 | set_bit(CSS_ROOT, &css->flags); | |
4023 | BUG_ON(cgrp->subsys[ss->subsys_id]); | |
4024 | cgrp->subsys[ss->subsys_id] = css; | |
4025 | ||
4026 | /* | |
4027 | * css holds an extra ref to @cgrp->dentry which is put on the last | |
4028 | * css_put(). dput() requires process context, which css_put() may | |
4029 | * be called without. @css->dput_work will be used to invoke | |
4030 | * dput() asynchronously from css_put(). | |
4031 | */ | |
4032 | INIT_WORK(&css->dput_work, css_dput_fn); | |
4033 | } | |
4034 | ||
4035 | /* | |
4036 | * cgroup_create - create a cgroup | |
4037 | * @parent: cgroup that will be parent of the new cgroup | |
4038 | * @dentry: dentry of the new cgroup | |
4039 | * @mode: mode to set on new inode | |
4040 | * | |
4041 | * Must be called with the mutex on the parent inode held | |
4042 | */ | |
4043 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, | |
4044 | umode_t mode) | |
4045 | { | |
4046 | struct cgroup *cgrp; | |
4047 | struct cgroupfs_root *root = parent->root; | |
4048 | int err = 0; | |
4049 | struct cgroup_subsys *ss; | |
4050 | struct super_block *sb = root->sb; | |
4051 | ||
4052 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); | |
4053 | if (!cgrp) | |
4054 | return -ENOMEM; | |
4055 | ||
4056 | /* | |
4057 | * Only live parents can have children. Note that the liveliness | |
4058 | * check isn't strictly necessary because cgroup_mkdir() and | |
4059 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it | |
4060 | * anyway so that locking is contained inside cgroup proper and we | |
4061 | * don't get nasty surprises if we ever grow another caller. | |
4062 | */ | |
4063 | if (!cgroup_lock_live_group(parent)) { | |
4064 | err = -ENODEV; | |
4065 | goto err_free; | |
4066 | } | |
4067 | ||
4068 | /* Grab a reference on the superblock so the hierarchy doesn't | |
4069 | * get deleted on unmount if there are child cgroups. This | |
4070 | * can be done outside cgroup_mutex, since the sb can't | |
4071 | * disappear while someone has an open control file on the | |
4072 | * fs */ | |
4073 | atomic_inc(&sb->s_active); | |
4074 | ||
4075 | init_cgroup_housekeeping(cgrp); | |
4076 | ||
4077 | cgrp->parent = parent; | |
4078 | cgrp->root = parent->root; | |
4079 | cgrp->top_cgroup = parent->top_cgroup; | |
4080 | ||
4081 | if (notify_on_release(parent)) | |
4082 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4083 | ||
4084 | if (clone_children(parent)) | |
4085 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); | |
4086 | ||
4087 | for_each_subsys(root, ss) { | |
4088 | struct cgroup_subsys_state *css; | |
4089 | ||
4090 | css = ss->create(cgrp); | |
4091 | if (IS_ERR(css)) { | |
4092 | err = PTR_ERR(css); | |
4093 | goto err_destroy; | |
4094 | } | |
4095 | init_cgroup_css(css, ss, cgrp); | |
4096 | if (ss->use_id) { | |
4097 | err = alloc_css_id(ss, parent, cgrp); | |
4098 | if (err) | |
4099 | goto err_destroy; | |
4100 | } | |
4101 | /* At error, ->destroy() callback has to free assigned ID. */ | |
4102 | if (clone_children(parent) && ss->post_clone) | |
4103 | ss->post_clone(cgrp); | |
4104 | ||
4105 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && | |
4106 | parent->parent) { | |
4107 | pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", | |
4108 | current->comm, current->pid, ss->name); | |
4109 | if (!strcmp(ss->name, "memory")) | |
4110 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); | |
4111 | ss->warned_broken_hierarchy = true; | |
4112 | } | |
4113 | } | |
4114 | ||
4115 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); | |
4116 | root->number_of_cgroups++; | |
4117 | ||
4118 | err = cgroup_create_file(dentry, S_IFDIR | mode, sb); | |
4119 | if (err < 0) | |
4120 | goto err_remove; | |
4121 | ||
4122 | dentry->d_fsdata = cgrp; | |
4123 | rcu_assign_pointer(cgrp->dentry, dentry); | |
4124 | ||
4125 | for_each_subsys(root, ss) { | |
4126 | /* each css holds a ref to the cgroup's dentry */ | |
4127 | dget(dentry); | |
4128 | ||
4129 | /* creation succeeded, notify subsystems */ | |
4130 | if (ss->post_create) | |
4131 | ss->post_create(cgrp); | |
4132 | } | |
4133 | ||
4134 | /* The cgroup directory was pre-locked for us */ | |
4135 | BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); | |
4136 | ||
4137 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); | |
4138 | ||
4139 | err = cgroup_populate_dir(cgrp, true, root->subsys_mask); | |
4140 | /* If err < 0, we have a half-filled directory - oh well ;) */ | |
4141 | ||
4142 | mutex_unlock(&cgroup_mutex); | |
4143 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); | |
4144 | ||
4145 | return 0; | |
4146 | ||
4147 | err_remove: | |
4148 | ||
4149 | list_del_rcu(&cgrp->sibling); | |
4150 | root->number_of_cgroups--; | |
4151 | ||
4152 | err_destroy: | |
4153 | ||
4154 | for_each_subsys(root, ss) { | |
4155 | if (cgrp->subsys[ss->subsys_id]) | |
4156 | ss->destroy(cgrp); | |
4157 | } | |
4158 | ||
4159 | mutex_unlock(&cgroup_mutex); | |
4160 | ||
4161 | /* Release the reference count that we took on the superblock */ | |
4162 | deactivate_super(sb); | |
4163 | err_free: | |
4164 | kfree(cgrp); | |
4165 | return err; | |
4166 | } | |
4167 | ||
4168 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) | |
4169 | { | |
4170 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
4171 | ||
4172 | /* the vfs holds inode->i_mutex already */ | |
4173 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
4174 | } | |
4175 | ||
4176 | /* | |
4177 | * Check the reference count on each subsystem. Since we already | |
4178 | * established that there are no tasks in the cgroup, if the css refcount | |
4179 | * is also 1, then there should be no outstanding references, so the | |
4180 | * subsystem is safe to destroy. We scan across all subsystems rather than | |
4181 | * using the per-hierarchy linked list of mounted subsystems since we can | |
4182 | * be called via check_for_release() with no synchronization other than | |
4183 | * RCU, and the subsystem linked list isn't RCU-safe. | |
4184 | */ | |
4185 | static int cgroup_has_css_refs(struct cgroup *cgrp) | |
4186 | { | |
4187 | int i; | |
4188 | ||
4189 | /* | |
4190 | * We won't need to lock the subsys array, because the subsystems | |
4191 | * we're concerned about aren't going anywhere since our cgroup root | |
4192 | * has a reference on them. | |
4193 | */ | |
4194 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
4195 | struct cgroup_subsys *ss = subsys[i]; | |
4196 | struct cgroup_subsys_state *css; | |
4197 | ||
4198 | /* Skip subsystems not present or not in this hierarchy */ | |
4199 | if (ss == NULL || ss->root != cgrp->root) | |
4200 | continue; | |
4201 | ||
4202 | css = cgrp->subsys[ss->subsys_id]; | |
4203 | /* | |
4204 | * When called from check_for_release() it's possible | |
4205 | * that by this point the cgroup has been removed | |
4206 | * and the css deleted. But a false-positive doesn't | |
4207 | * matter, since it can only happen if the cgroup | |
4208 | * has been deleted and hence no longer needs the | |
4209 | * release agent to be called anyway. | |
4210 | */ | |
4211 | if (css && css_refcnt(css) > 1) | |
4212 | return 1; | |
4213 | } | |
4214 | return 0; | |
4215 | } | |
4216 | ||
4217 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) | |
4218 | { | |
4219 | struct cgroup *cgrp = dentry->d_fsdata; | |
4220 | struct dentry *d; | |
4221 | struct cgroup *parent; | |
4222 | DEFINE_WAIT(wait); | |
4223 | struct cgroup_event *event, *tmp; | |
4224 | struct cgroup_subsys *ss; | |
4225 | ||
4226 | /* the vfs holds both inode->i_mutex already */ | |
4227 | mutex_lock(&cgroup_mutex); | |
4228 | parent = cgrp->parent; | |
4229 | if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { | |
4230 | mutex_unlock(&cgroup_mutex); | |
4231 | return -EBUSY; | |
4232 | } | |
4233 | ||
4234 | /* | |
4235 | * Block new css_tryget() by deactivating refcnt and mark @cgrp | |
4236 | * removed. This makes future css_tryget() and child creation | |
4237 | * attempts fail thus maintaining the removal conditions verified | |
4238 | * above. | |
4239 | */ | |
4240 | for_each_subsys(cgrp->root, ss) { | |
4241 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
4242 | ||
4243 | WARN_ON(atomic_read(&css->refcnt) < 0); | |
4244 | atomic_add(CSS_DEACT_BIAS, &css->refcnt); | |
4245 | } | |
4246 | set_bit(CGRP_REMOVED, &cgrp->flags); | |
4247 | ||
4248 | /* | |
4249 | * Tell subsystems to initate destruction. pre_destroy() should be | |
4250 | * called with cgroup_mutex unlocked. See 3fa59dfbc3 ("cgroup: fix | |
4251 | * potential deadlock in pre_destroy") for details. | |
4252 | */ | |
4253 | mutex_unlock(&cgroup_mutex); | |
4254 | for_each_subsys(cgrp->root, ss) | |
4255 | if (ss->pre_destroy) | |
4256 | ss->pre_destroy(cgrp); | |
4257 | mutex_lock(&cgroup_mutex); | |
4258 | ||
4259 | /* | |
4260 | * Put all the base refs. Each css holds an extra reference to the | |
4261 | * cgroup's dentry and cgroup removal proceeds regardless of css | |
4262 | * refs. On the last put of each css, whenever that may be, the | |
4263 | * extra dentry ref is put so that dentry destruction happens only | |
4264 | * after all css's are released. | |
4265 | */ | |
4266 | for_each_subsys(cgrp->root, ss) | |
4267 | css_put(cgrp->subsys[ss->subsys_id]); | |
4268 | ||
4269 | raw_spin_lock(&release_list_lock); | |
4270 | if (!list_empty(&cgrp->release_list)) | |
4271 | list_del_init(&cgrp->release_list); | |
4272 | raw_spin_unlock(&release_list_lock); | |
4273 | ||
4274 | /* delete this cgroup from parent->children */ | |
4275 | list_del_rcu(&cgrp->sibling); | |
4276 | ||
4277 | list_del_init(&cgrp->allcg_node); | |
4278 | ||
4279 | d = dget(cgrp->dentry); | |
4280 | ||
4281 | cgroup_d_remove_dir(d); | |
4282 | dput(d); | |
4283 | ||
4284 | set_bit(CGRP_RELEASABLE, &parent->flags); | |
4285 | check_for_release(parent); | |
4286 | ||
4287 | /* | |
4288 | * Unregister events and notify userspace. | |
4289 | * Notify userspace about cgroup removing only after rmdir of cgroup | |
4290 | * directory to avoid race between userspace and kernelspace | |
4291 | */ | |
4292 | spin_lock(&cgrp->event_list_lock); | |
4293 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { | |
4294 | list_del(&event->list); | |
4295 | remove_wait_queue(event->wqh, &event->wait); | |
4296 | eventfd_signal(event->eventfd, 1); | |
4297 | schedule_work(&event->remove); | |
4298 | } | |
4299 | spin_unlock(&cgrp->event_list_lock); | |
4300 | ||
4301 | mutex_unlock(&cgroup_mutex); | |
4302 | return 0; | |
4303 | } | |
4304 | ||
4305 | static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) | |
4306 | { | |
4307 | INIT_LIST_HEAD(&ss->cftsets); | |
4308 | ||
4309 | /* | |
4310 | * base_cftset is embedded in subsys itself, no need to worry about | |
4311 | * deregistration. | |
4312 | */ | |
4313 | if (ss->base_cftypes) { | |
4314 | ss->base_cftset.cfts = ss->base_cftypes; | |
4315 | list_add_tail(&ss->base_cftset.node, &ss->cftsets); | |
4316 | } | |
4317 | } | |
4318 | ||
4319 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) | |
4320 | { | |
4321 | struct cgroup_subsys_state *css; | |
4322 | ||
4323 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
4324 | ||
4325 | /* init base cftset */ | |
4326 | cgroup_init_cftsets(ss); | |
4327 | ||
4328 | /* Create the top cgroup state for this subsystem */ | |
4329 | list_add(&ss->sibling, &rootnode.subsys_list); | |
4330 | ss->root = &rootnode; | |
4331 | css = ss->create(dummytop); | |
4332 | /* We don't handle early failures gracefully */ | |
4333 | BUG_ON(IS_ERR(css)); | |
4334 | init_cgroup_css(css, ss, dummytop); | |
4335 | ||
4336 | /* Update the init_css_set to contain a subsys | |
4337 | * pointer to this state - since the subsystem is | |
4338 | * newly registered, all tasks and hence the | |
4339 | * init_css_set is in the subsystem's top cgroup. */ | |
4340 | init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id]; | |
4341 | ||
4342 | need_forkexit_callback |= ss->fork || ss->exit; | |
4343 | ||
4344 | /* At system boot, before all subsystems have been | |
4345 | * registered, no tasks have been forked, so we don't | |
4346 | * need to invoke fork callbacks here. */ | |
4347 | BUG_ON(!list_empty(&init_task.tasks)); | |
4348 | ||
4349 | ss->active = 1; | |
4350 | ||
4351 | if (ss->post_create) | |
4352 | ss->post_create(&ss->root->top_cgroup); | |
4353 | ||
4354 | /* this function shouldn't be used with modular subsystems, since they | |
4355 | * need to register a subsys_id, among other things */ | |
4356 | BUG_ON(ss->module); | |
4357 | } | |
4358 | ||
4359 | /** | |
4360 | * cgroup_load_subsys: load and register a modular subsystem at runtime | |
4361 | * @ss: the subsystem to load | |
4362 | * | |
4363 | * This function should be called in a modular subsystem's initcall. If the | |
4364 | * subsystem is built as a module, it will be assigned a new subsys_id and set | |
4365 | * up for use. If the subsystem is built-in anyway, work is delegated to the | |
4366 | * simpler cgroup_init_subsys. | |
4367 | */ | |
4368 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) | |
4369 | { | |
4370 | int i; | |
4371 | struct cgroup_subsys_state *css; | |
4372 | ||
4373 | /* check name and function validity */ | |
4374 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || | |
4375 | ss->create == NULL || ss->destroy == NULL) | |
4376 | return -EINVAL; | |
4377 | ||
4378 | /* | |
4379 | * we don't support callbacks in modular subsystems. this check is | |
4380 | * before the ss->module check for consistency; a subsystem that could | |
4381 | * be a module should still have no callbacks even if the user isn't | |
4382 | * compiling it as one. | |
4383 | */ | |
4384 | if (ss->fork || ss->exit) | |
4385 | return -EINVAL; | |
4386 | ||
4387 | /* | |
4388 | * an optionally modular subsystem is built-in: we want to do nothing, | |
4389 | * since cgroup_init_subsys will have already taken care of it. | |
4390 | */ | |
4391 | if (ss->module == NULL) { | |
4392 | /* a sanity check */ | |
4393 | BUG_ON(subsys[ss->subsys_id] != ss); | |
4394 | return 0; | |
4395 | } | |
4396 | ||
4397 | /* init base cftset */ | |
4398 | cgroup_init_cftsets(ss); | |
4399 | ||
4400 | mutex_lock(&cgroup_mutex); | |
4401 | subsys[ss->subsys_id] = ss; | |
4402 | ||
4403 | /* | |
4404 | * no ss->create seems to need anything important in the ss struct, so | |
4405 | * this can happen first (i.e. before the rootnode attachment). | |
4406 | */ | |
4407 | css = ss->create(dummytop); | |
4408 | if (IS_ERR(css)) { | |
4409 | /* failure case - need to deassign the subsys[] slot. */ | |
4410 | subsys[ss->subsys_id] = NULL; | |
4411 | mutex_unlock(&cgroup_mutex); | |
4412 | return PTR_ERR(css); | |
4413 | } | |
4414 | ||
4415 | list_add(&ss->sibling, &rootnode.subsys_list); | |
4416 | ss->root = &rootnode; | |
4417 | ||
4418 | /* our new subsystem will be attached to the dummy hierarchy. */ | |
4419 | init_cgroup_css(css, ss, dummytop); | |
4420 | /* init_idr must be after init_cgroup_css because it sets css->id. */ | |
4421 | if (ss->use_id) { | |
4422 | int ret = cgroup_init_idr(ss, css); | |
4423 | if (ret) { | |
4424 | dummytop->subsys[ss->subsys_id] = NULL; | |
4425 | ss->destroy(dummytop); | |
4426 | subsys[ss->subsys_id] = NULL; | |
4427 | mutex_unlock(&cgroup_mutex); | |
4428 | return ret; | |
4429 | } | |
4430 | } | |
4431 | ||
4432 | /* | |
4433 | * Now we need to entangle the css into the existing css_sets. unlike | |
4434 | * in cgroup_init_subsys, there are now multiple css_sets, so each one | |
4435 | * will need a new pointer to it; done by iterating the css_set_table. | |
4436 | * furthermore, modifying the existing css_sets will corrupt the hash | |
4437 | * table state, so each changed css_set will need its hash recomputed. | |
4438 | * this is all done under the css_set_lock. | |
4439 | */ | |
4440 | write_lock(&css_set_lock); | |
4441 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { | |
4442 | struct css_set *cg; | |
4443 | struct hlist_node *node, *tmp; | |
4444 | struct hlist_head *bucket = &css_set_table[i], *new_bucket; | |
4445 | ||
4446 | hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { | |
4447 | /* skip entries that we already rehashed */ | |
4448 | if (cg->subsys[ss->subsys_id]) | |
4449 | continue; | |
4450 | /* remove existing entry */ | |
4451 | hlist_del(&cg->hlist); | |
4452 | /* set new value */ | |
4453 | cg->subsys[ss->subsys_id] = css; | |
4454 | /* recompute hash and restore entry */ | |
4455 | new_bucket = css_set_hash(cg->subsys); | |
4456 | hlist_add_head(&cg->hlist, new_bucket); | |
4457 | } | |
4458 | } | |
4459 | write_unlock(&css_set_lock); | |
4460 | ||
4461 | ss->active = 1; | |
4462 | ||
4463 | if (ss->post_create) | |
4464 | ss->post_create(&ss->root->top_cgroup); | |
4465 | ||
4466 | /* success! */ | |
4467 | mutex_unlock(&cgroup_mutex); | |
4468 | return 0; | |
4469 | } | |
4470 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); | |
4471 | ||
4472 | /** | |
4473 | * cgroup_unload_subsys: unload a modular subsystem | |
4474 | * @ss: the subsystem to unload | |
4475 | * | |
4476 | * This function should be called in a modular subsystem's exitcall. When this | |
4477 | * function is invoked, the refcount on the subsystem's module will be 0, so | |
4478 | * the subsystem will not be attached to any hierarchy. | |
4479 | */ | |
4480 | void cgroup_unload_subsys(struct cgroup_subsys *ss) | |
4481 | { | |
4482 | struct cg_cgroup_link *link; | |
4483 | struct hlist_head *hhead; | |
4484 | ||
4485 | BUG_ON(ss->module == NULL); | |
4486 | ||
4487 | /* | |
4488 | * we shouldn't be called if the subsystem is in use, and the use of | |
4489 | * try_module_get in parse_cgroupfs_options should ensure that it | |
4490 | * doesn't start being used while we're killing it off. | |
4491 | */ | |
4492 | BUG_ON(ss->root != &rootnode); | |
4493 | ||
4494 | mutex_lock(&cgroup_mutex); | |
4495 | /* deassign the subsys_id */ | |
4496 | subsys[ss->subsys_id] = NULL; | |
4497 | ||
4498 | /* remove subsystem from rootnode's list of subsystems */ | |
4499 | list_del_init(&ss->sibling); | |
4500 | ||
4501 | /* | |
4502 | * disentangle the css from all css_sets attached to the dummytop. as | |
4503 | * in loading, we need to pay our respects to the hashtable gods. | |
4504 | */ | |
4505 | write_lock(&css_set_lock); | |
4506 | list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { | |
4507 | struct css_set *cg = link->cg; | |
4508 | ||
4509 | hlist_del(&cg->hlist); | |
4510 | BUG_ON(!cg->subsys[ss->subsys_id]); | |
4511 | cg->subsys[ss->subsys_id] = NULL; | |
4512 | hhead = css_set_hash(cg->subsys); | |
4513 | hlist_add_head(&cg->hlist, hhead); | |
4514 | } | |
4515 | write_unlock(&css_set_lock); | |
4516 | ||
4517 | /* | |
4518 | * remove subsystem's css from the dummytop and free it - need to free | |
4519 | * before marking as null because ss->destroy needs the cgrp->subsys | |
4520 | * pointer to find their state. note that this also takes care of | |
4521 | * freeing the css_id. | |
4522 | */ | |
4523 | ss->destroy(dummytop); | |
4524 | dummytop->subsys[ss->subsys_id] = NULL; | |
4525 | ||
4526 | mutex_unlock(&cgroup_mutex); | |
4527 | } | |
4528 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); | |
4529 | ||
4530 | /** | |
4531 | * cgroup_init_early - cgroup initialization at system boot | |
4532 | * | |
4533 | * Initialize cgroups at system boot, and initialize any | |
4534 | * subsystems that request early init. | |
4535 | */ | |
4536 | int __init cgroup_init_early(void) | |
4537 | { | |
4538 | int i; | |
4539 | atomic_set(&init_css_set.refcount, 1); | |
4540 | INIT_LIST_HEAD(&init_css_set.cg_links); | |
4541 | INIT_LIST_HEAD(&init_css_set.tasks); | |
4542 | INIT_HLIST_NODE(&init_css_set.hlist); | |
4543 | css_set_count = 1; | |
4544 | init_cgroup_root(&rootnode); | |
4545 | root_count = 1; | |
4546 | init_task.cgroups = &init_css_set; | |
4547 | ||
4548 | init_css_set_link.cg = &init_css_set; | |
4549 | init_css_set_link.cgrp = dummytop; | |
4550 | list_add(&init_css_set_link.cgrp_link_list, | |
4551 | &rootnode.top_cgroup.css_sets); | |
4552 | list_add(&init_css_set_link.cg_link_list, | |
4553 | &init_css_set.cg_links); | |
4554 | ||
4555 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) | |
4556 | INIT_HLIST_HEAD(&css_set_table[i]); | |
4557 | ||
4558 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
4559 | struct cgroup_subsys *ss = subsys[i]; | |
4560 | ||
4561 | /* at bootup time, we don't worry about modular subsystems */ | |
4562 | if (!ss || ss->module) | |
4563 | continue; | |
4564 | ||
4565 | BUG_ON(!ss->name); | |
4566 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
4567 | BUG_ON(!ss->create); | |
4568 | BUG_ON(!ss->destroy); | |
4569 | if (ss->subsys_id != i) { | |
4570 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", | |
4571 | ss->name, ss->subsys_id); | |
4572 | BUG(); | |
4573 | } | |
4574 | ||
4575 | if (ss->early_init) | |
4576 | cgroup_init_subsys(ss); | |
4577 | } | |
4578 | return 0; | |
4579 | } | |
4580 | ||
4581 | /** | |
4582 | * cgroup_init - cgroup initialization | |
4583 | * | |
4584 | * Register cgroup filesystem and /proc file, and initialize | |
4585 | * any subsystems that didn't request early init. | |
4586 | */ | |
4587 | int __init cgroup_init(void) | |
4588 | { | |
4589 | int err; | |
4590 | int i; | |
4591 | struct hlist_head *hhead; | |
4592 | ||
4593 | err = bdi_init(&cgroup_backing_dev_info); | |
4594 | if (err) | |
4595 | return err; | |
4596 | ||
4597 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
4598 | struct cgroup_subsys *ss = subsys[i]; | |
4599 | ||
4600 | /* at bootup time, we don't worry about modular subsystems */ | |
4601 | if (!ss || ss->module) | |
4602 | continue; | |
4603 | if (!ss->early_init) | |
4604 | cgroup_init_subsys(ss); | |
4605 | if (ss->use_id) | |
4606 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); | |
4607 | } | |
4608 | ||
4609 | /* Add init_css_set to the hash table */ | |
4610 | hhead = css_set_hash(init_css_set.subsys); | |
4611 | hlist_add_head(&init_css_set.hlist, hhead); | |
4612 | BUG_ON(!init_root_id(&rootnode)); | |
4613 | ||
4614 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); | |
4615 | if (!cgroup_kobj) { | |
4616 | err = -ENOMEM; | |
4617 | goto out; | |
4618 | } | |
4619 | ||
4620 | err = register_filesystem(&cgroup_fs_type); | |
4621 | if (err < 0) { | |
4622 | kobject_put(cgroup_kobj); | |
4623 | goto out; | |
4624 | } | |
4625 | ||
4626 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); | |
4627 | ||
4628 | out: | |
4629 | if (err) | |
4630 | bdi_destroy(&cgroup_backing_dev_info); | |
4631 | ||
4632 | return err; | |
4633 | } | |
4634 | ||
4635 | /* | |
4636 | * proc_cgroup_show() | |
4637 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4638 | * - Used for /proc/<pid>/cgroup. | |
4639 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
4640 | * doesn't really matter if tsk->cgroup changes after we read it, | |
4641 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it | |
4642 | * anyway. No need to check that tsk->cgroup != NULL, thanks to | |
4643 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
4644 | * cgroup to top_cgroup. | |
4645 | */ | |
4646 | ||
4647 | /* TODO: Use a proper seq_file iterator */ | |
4648 | static int proc_cgroup_show(struct seq_file *m, void *v) | |
4649 | { | |
4650 | struct pid *pid; | |
4651 | struct task_struct *tsk; | |
4652 | char *buf; | |
4653 | int retval; | |
4654 | struct cgroupfs_root *root; | |
4655 | ||
4656 | retval = -ENOMEM; | |
4657 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
4658 | if (!buf) | |
4659 | goto out; | |
4660 | ||
4661 | retval = -ESRCH; | |
4662 | pid = m->private; | |
4663 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4664 | if (!tsk) | |
4665 | goto out_free; | |
4666 | ||
4667 | retval = 0; | |
4668 | ||
4669 | mutex_lock(&cgroup_mutex); | |
4670 | ||
4671 | for_each_active_root(root) { | |
4672 | struct cgroup_subsys *ss; | |
4673 | struct cgroup *cgrp; | |
4674 | int count = 0; | |
4675 | ||
4676 | seq_printf(m, "%d:", root->hierarchy_id); | |
4677 | for_each_subsys(root, ss) | |
4678 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
4679 | if (strlen(root->name)) | |
4680 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4681 | root->name); | |
4682 | seq_putc(m, ':'); | |
4683 | cgrp = task_cgroup_from_root(tsk, root); | |
4684 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); | |
4685 | if (retval < 0) | |
4686 | goto out_unlock; | |
4687 | seq_puts(m, buf); | |
4688 | seq_putc(m, '\n'); | |
4689 | } | |
4690 | ||
4691 | out_unlock: | |
4692 | mutex_unlock(&cgroup_mutex); | |
4693 | put_task_struct(tsk); | |
4694 | out_free: | |
4695 | kfree(buf); | |
4696 | out: | |
4697 | return retval; | |
4698 | } | |
4699 | ||
4700 | static int cgroup_open(struct inode *inode, struct file *file) | |
4701 | { | |
4702 | struct pid *pid = PROC_I(inode)->pid; | |
4703 | return single_open(file, proc_cgroup_show, pid); | |
4704 | } | |
4705 | ||
4706 | const struct file_operations proc_cgroup_operations = { | |
4707 | .open = cgroup_open, | |
4708 | .read = seq_read, | |
4709 | .llseek = seq_lseek, | |
4710 | .release = single_release, | |
4711 | }; | |
4712 | ||
4713 | /* Display information about each subsystem and each hierarchy */ | |
4714 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4715 | { | |
4716 | int i; | |
4717 | ||
4718 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); | |
4719 | /* | |
4720 | * ideally we don't want subsystems moving around while we do this. | |
4721 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4722 | * subsys/hierarchy state. | |
4723 | */ | |
4724 | mutex_lock(&cgroup_mutex); | |
4725 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
4726 | struct cgroup_subsys *ss = subsys[i]; | |
4727 | if (ss == NULL) | |
4728 | continue; | |
4729 | seq_printf(m, "%s\t%d\t%d\t%d\n", | |
4730 | ss->name, ss->root->hierarchy_id, | |
4731 | ss->root->number_of_cgroups, !ss->disabled); | |
4732 | } | |
4733 | mutex_unlock(&cgroup_mutex); | |
4734 | return 0; | |
4735 | } | |
4736 | ||
4737 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4738 | { | |
4739 | return single_open(file, proc_cgroupstats_show, NULL); | |
4740 | } | |
4741 | ||
4742 | static const struct file_operations proc_cgroupstats_operations = { | |
4743 | .open = cgroupstats_open, | |
4744 | .read = seq_read, | |
4745 | .llseek = seq_lseek, | |
4746 | .release = single_release, | |
4747 | }; | |
4748 | ||
4749 | /** | |
4750 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
4751 | * @child: pointer to task_struct of forking parent process. | |
4752 | * | |
4753 | * Description: A task inherits its parent's cgroup at fork(). | |
4754 | * | |
4755 | * A pointer to the shared css_set was automatically copied in | |
4756 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
4757 | * it was not made under the protection of RCU or cgroup_mutex, so | |
4758 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might | |
4759 | * have already changed current->cgroups, allowing the previously | |
4760 | * referenced cgroup group to be removed and freed. | |
4761 | * | |
4762 | * At the point that cgroup_fork() is called, 'current' is the parent | |
4763 | * task, and the passed argument 'child' points to the child task. | |
4764 | */ | |
4765 | void cgroup_fork(struct task_struct *child) | |
4766 | { | |
4767 | task_lock(current); | |
4768 | child->cgroups = current->cgroups; | |
4769 | get_css_set(child->cgroups); | |
4770 | task_unlock(current); | |
4771 | INIT_LIST_HEAD(&child->cg_list); | |
4772 | } | |
4773 | ||
4774 | /** | |
4775 | * cgroup_post_fork - called on a new task after adding it to the task list | |
4776 | * @child: the task in question | |
4777 | * | |
4778 | * Adds the task to the list running through its css_set if necessary and | |
4779 | * call the subsystem fork() callbacks. Has to be after the task is | |
4780 | * visible on the task list in case we race with the first call to | |
4781 | * cgroup_iter_start() - to guarantee that the new task ends up on its | |
4782 | * list. | |
4783 | */ | |
4784 | void cgroup_post_fork(struct task_struct *child) | |
4785 | { | |
4786 | int i; | |
4787 | ||
4788 | /* | |
4789 | * use_task_css_set_links is set to 1 before we walk the tasklist | |
4790 | * under the tasklist_lock and we read it here after we added the child | |
4791 | * to the tasklist under the tasklist_lock as well. If the child wasn't | |
4792 | * yet in the tasklist when we walked through it from | |
4793 | * cgroup_enable_task_cg_lists(), then use_task_css_set_links value | |
4794 | * should be visible now due to the paired locking and barriers implied | |
4795 | * by LOCK/UNLOCK: it is written before the tasklist_lock unlock | |
4796 | * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock | |
4797 | * lock on fork. | |
4798 | */ | |
4799 | if (use_task_css_set_links) { | |
4800 | write_lock(&css_set_lock); | |
4801 | task_lock(child); | |
4802 | if (list_empty(&child->cg_list)) | |
4803 | list_add(&child->cg_list, &child->cgroups->tasks); | |
4804 | task_unlock(child); | |
4805 | write_unlock(&css_set_lock); | |
4806 | } | |
4807 | ||
4808 | /* | |
4809 | * Call ss->fork(). This must happen after @child is linked on | |
4810 | * css_set; otherwise, @child might change state between ->fork() | |
4811 | * and addition to css_set. | |
4812 | */ | |
4813 | if (need_forkexit_callback) { | |
4814 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
4815 | struct cgroup_subsys *ss = subsys[i]; | |
4816 | ||
4817 | /* | |
4818 | * fork/exit callbacks are supported only for | |
4819 | * builtin subsystems and we don't need further | |
4820 | * synchronization as they never go away. | |
4821 | */ | |
4822 | if (!ss || ss->module) | |
4823 | continue; | |
4824 | ||
4825 | if (ss->fork) | |
4826 | ss->fork(child); | |
4827 | } | |
4828 | } | |
4829 | } | |
4830 | ||
4831 | /** | |
4832 | * cgroup_exit - detach cgroup from exiting task | |
4833 | * @tsk: pointer to task_struct of exiting process | |
4834 | * @run_callback: run exit callbacks? | |
4835 | * | |
4836 | * Description: Detach cgroup from @tsk and release it. | |
4837 | * | |
4838 | * Note that cgroups marked notify_on_release force every task in | |
4839 | * them to take the global cgroup_mutex mutex when exiting. | |
4840 | * This could impact scaling on very large systems. Be reluctant to | |
4841 | * use notify_on_release cgroups where very high task exit scaling | |
4842 | * is required on large systems. | |
4843 | * | |
4844 | * the_top_cgroup_hack: | |
4845 | * | |
4846 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
4847 | * | |
4848 | * We call cgroup_exit() while the task is still competent to | |
4849 | * handle notify_on_release(), then leave the task attached to the | |
4850 | * root cgroup in each hierarchy for the remainder of its exit. | |
4851 | * | |
4852 | * To do this properly, we would increment the reference count on | |
4853 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
4854 | * code we would add a second cgroup function call, to drop that | |
4855 | * reference. This would just create an unnecessary hot spot on | |
4856 | * the top_cgroup reference count, to no avail. | |
4857 | * | |
4858 | * Normally, holding a reference to a cgroup without bumping its | |
4859 | * count is unsafe. The cgroup could go away, or someone could | |
4860 | * attach us to a different cgroup, decrementing the count on | |
4861 | * the first cgroup that we never incremented. But in this case, | |
4862 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
4863 | * which wards off any cgroup_attach_task() attempts, or task is a failed | |
4864 | * fork, never visible to cgroup_attach_task. | |
4865 | */ | |
4866 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
4867 | { | |
4868 | struct css_set *cg; | |
4869 | int i; | |
4870 | ||
4871 | /* | |
4872 | * Unlink from the css_set task list if necessary. | |
4873 | * Optimistically check cg_list before taking | |
4874 | * css_set_lock | |
4875 | */ | |
4876 | if (!list_empty(&tsk->cg_list)) { | |
4877 | write_lock(&css_set_lock); | |
4878 | if (!list_empty(&tsk->cg_list)) | |
4879 | list_del_init(&tsk->cg_list); | |
4880 | write_unlock(&css_set_lock); | |
4881 | } | |
4882 | ||
4883 | /* Reassign the task to the init_css_set. */ | |
4884 | task_lock(tsk); | |
4885 | cg = tsk->cgroups; | |
4886 | tsk->cgroups = &init_css_set; | |
4887 | ||
4888 | if (run_callbacks && need_forkexit_callback) { | |
4889 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
4890 | struct cgroup_subsys *ss = subsys[i]; | |
4891 | ||
4892 | /* modular subsystems can't use callbacks */ | |
4893 | if (!ss || ss->module) | |
4894 | continue; | |
4895 | ||
4896 | if (ss->exit) { | |
4897 | struct cgroup *old_cgrp = | |
4898 | rcu_dereference_raw(cg->subsys[i])->cgroup; | |
4899 | struct cgroup *cgrp = task_cgroup(tsk, i); | |
4900 | ss->exit(cgrp, old_cgrp, tsk); | |
4901 | } | |
4902 | } | |
4903 | } | |
4904 | task_unlock(tsk); | |
4905 | ||
4906 | if (cg) | |
4907 | put_css_set_taskexit(cg); | |
4908 | } | |
4909 | ||
4910 | /** | |
4911 | * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp | |
4912 | * @cgrp: the cgroup in question | |
4913 | * @task: the task in question | |
4914 | * | |
4915 | * See if @cgrp is a descendant of @task's cgroup in the appropriate | |
4916 | * hierarchy. | |
4917 | * | |
4918 | * If we are sending in dummytop, then presumably we are creating | |
4919 | * the top cgroup in the subsystem. | |
4920 | * | |
4921 | * Called only by the ns (nsproxy) cgroup. | |
4922 | */ | |
4923 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) | |
4924 | { | |
4925 | int ret; | |
4926 | struct cgroup *target; | |
4927 | ||
4928 | if (cgrp == dummytop) | |
4929 | return 1; | |
4930 | ||
4931 | target = task_cgroup_from_root(task, cgrp->root); | |
4932 | while (cgrp != target && cgrp!= cgrp->top_cgroup) | |
4933 | cgrp = cgrp->parent; | |
4934 | ret = (cgrp == target); | |
4935 | return ret; | |
4936 | } | |
4937 | ||
4938 | static void check_for_release(struct cgroup *cgrp) | |
4939 | { | |
4940 | /* All of these checks rely on RCU to keep the cgroup | |
4941 | * structure alive */ | |
4942 | if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) | |
4943 | && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { | |
4944 | /* Control Group is currently removeable. If it's not | |
4945 | * already queued for a userspace notification, queue | |
4946 | * it now */ | |
4947 | int need_schedule_work = 0; | |
4948 | raw_spin_lock(&release_list_lock); | |
4949 | if (!cgroup_is_removed(cgrp) && | |
4950 | list_empty(&cgrp->release_list)) { | |
4951 | list_add(&cgrp->release_list, &release_list); | |
4952 | need_schedule_work = 1; | |
4953 | } | |
4954 | raw_spin_unlock(&release_list_lock); | |
4955 | if (need_schedule_work) | |
4956 | schedule_work(&release_agent_work); | |
4957 | } | |
4958 | } | |
4959 | ||
4960 | /* Caller must verify that the css is not for root cgroup */ | |
4961 | bool __css_tryget(struct cgroup_subsys_state *css) | |
4962 | { | |
4963 | while (true) { | |
4964 | int t, v; | |
4965 | ||
4966 | v = css_refcnt(css); | |
4967 | t = atomic_cmpxchg(&css->refcnt, v, v + 1); | |
4968 | if (likely(t == v)) | |
4969 | return true; | |
4970 | else if (t < 0) | |
4971 | return false; | |
4972 | cpu_relax(); | |
4973 | } | |
4974 | } | |
4975 | EXPORT_SYMBOL_GPL(__css_tryget); | |
4976 | ||
4977 | /* Caller must verify that the css is not for root cgroup */ | |
4978 | void __css_put(struct cgroup_subsys_state *css) | |
4979 | { | |
4980 | struct cgroup *cgrp = css->cgroup; | |
4981 | int v; | |
4982 | ||
4983 | rcu_read_lock(); | |
4984 | v = css_unbias_refcnt(atomic_dec_return(&css->refcnt)); | |
4985 | ||
4986 | switch (v) { | |
4987 | case 1: | |
4988 | if (notify_on_release(cgrp)) { | |
4989 | set_bit(CGRP_RELEASABLE, &cgrp->flags); | |
4990 | check_for_release(cgrp); | |
4991 | } | |
4992 | break; | |
4993 | case 0: | |
4994 | schedule_work(&css->dput_work); | |
4995 | break; | |
4996 | } | |
4997 | rcu_read_unlock(); | |
4998 | } | |
4999 | EXPORT_SYMBOL_GPL(__css_put); | |
5000 | ||
5001 | /* | |
5002 | * Notify userspace when a cgroup is released, by running the | |
5003 | * configured release agent with the name of the cgroup (path | |
5004 | * relative to the root of cgroup file system) as the argument. | |
5005 | * | |
5006 | * Most likely, this user command will try to rmdir this cgroup. | |
5007 | * | |
5008 | * This races with the possibility that some other task will be | |
5009 | * attached to this cgroup before it is removed, or that some other | |
5010 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5011 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5012 | * unused, and this cgroup will be reprieved from its death sentence, | |
5013 | * to continue to serve a useful existence. Next time it's released, | |
5014 | * we will get notified again, if it still has 'notify_on_release' set. | |
5015 | * | |
5016 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5017 | * means only wait until the task is successfully execve()'d. The | |
5018 | * separate release agent task is forked by call_usermodehelper(), | |
5019 | * then control in this thread returns here, without waiting for the | |
5020 | * release agent task. We don't bother to wait because the caller of | |
5021 | * this routine has no use for the exit status of the release agent | |
5022 | * task, so no sense holding our caller up for that. | |
5023 | */ | |
5024 | static void cgroup_release_agent(struct work_struct *work) | |
5025 | { | |
5026 | BUG_ON(work != &release_agent_work); | |
5027 | mutex_lock(&cgroup_mutex); | |
5028 | raw_spin_lock(&release_list_lock); | |
5029 | while (!list_empty(&release_list)) { | |
5030 | char *argv[3], *envp[3]; | |
5031 | int i; | |
5032 | char *pathbuf = NULL, *agentbuf = NULL; | |
5033 | struct cgroup *cgrp = list_entry(release_list.next, | |
5034 | struct cgroup, | |
5035 | release_list); | |
5036 | list_del_init(&cgrp->release_list); | |
5037 | raw_spin_unlock(&release_list_lock); | |
5038 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
5039 | if (!pathbuf) | |
5040 | goto continue_free; | |
5041 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
5042 | goto continue_free; | |
5043 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5044 | if (!agentbuf) | |
5045 | goto continue_free; | |
5046 | ||
5047 | i = 0; | |
5048 | argv[i++] = agentbuf; | |
5049 | argv[i++] = pathbuf; | |
5050 | argv[i] = NULL; | |
5051 | ||
5052 | i = 0; | |
5053 | /* minimal command environment */ | |
5054 | envp[i++] = "HOME=/"; | |
5055 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5056 | envp[i] = NULL; | |
5057 | ||
5058 | /* Drop the lock while we invoke the usermode helper, | |
5059 | * since the exec could involve hitting disk and hence | |
5060 | * be a slow process */ | |
5061 | mutex_unlock(&cgroup_mutex); | |
5062 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
5063 | mutex_lock(&cgroup_mutex); | |
5064 | continue_free: | |
5065 | kfree(pathbuf); | |
5066 | kfree(agentbuf); | |
5067 | raw_spin_lock(&release_list_lock); | |
5068 | } | |
5069 | raw_spin_unlock(&release_list_lock); | |
5070 | mutex_unlock(&cgroup_mutex); | |
5071 | } | |
5072 | ||
5073 | static int __init cgroup_disable(char *str) | |
5074 | { | |
5075 | int i; | |
5076 | char *token; | |
5077 | ||
5078 | while ((token = strsep(&str, ",")) != NULL) { | |
5079 | if (!*token) | |
5080 | continue; | |
5081 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
5082 | struct cgroup_subsys *ss = subsys[i]; | |
5083 | ||
5084 | /* | |
5085 | * cgroup_disable, being at boot time, can't | |
5086 | * know about module subsystems, so we don't | |
5087 | * worry about them. | |
5088 | */ | |
5089 | if (!ss || ss->module) | |
5090 | continue; | |
5091 | ||
5092 | if (!strcmp(token, ss->name)) { | |
5093 | ss->disabled = 1; | |
5094 | printk(KERN_INFO "Disabling %s control group" | |
5095 | " subsystem\n", ss->name); | |
5096 | break; | |
5097 | } | |
5098 | } | |
5099 | } | |
5100 | return 1; | |
5101 | } | |
5102 | __setup("cgroup_disable=", cgroup_disable); | |
5103 | ||
5104 | /* | |
5105 | * Functons for CSS ID. | |
5106 | */ | |
5107 | ||
5108 | /* | |
5109 | *To get ID other than 0, this should be called when !cgroup_is_removed(). | |
5110 | */ | |
5111 | unsigned short css_id(struct cgroup_subsys_state *css) | |
5112 | { | |
5113 | struct css_id *cssid; | |
5114 | ||
5115 | /* | |
5116 | * This css_id() can return correct value when somone has refcnt | |
5117 | * on this or this is under rcu_read_lock(). Once css->id is allocated, | |
5118 | * it's unchanged until freed. | |
5119 | */ | |
5120 | cssid = rcu_dereference_check(css->id, css_refcnt(css)); | |
5121 | ||
5122 | if (cssid) | |
5123 | return cssid->id; | |
5124 | return 0; | |
5125 | } | |
5126 | EXPORT_SYMBOL_GPL(css_id); | |
5127 | ||
5128 | unsigned short css_depth(struct cgroup_subsys_state *css) | |
5129 | { | |
5130 | struct css_id *cssid; | |
5131 | ||
5132 | cssid = rcu_dereference_check(css->id, css_refcnt(css)); | |
5133 | ||
5134 | if (cssid) | |
5135 | return cssid->depth; | |
5136 | return 0; | |
5137 | } | |
5138 | EXPORT_SYMBOL_GPL(css_depth); | |
5139 | ||
5140 | /** | |
5141 | * css_is_ancestor - test "root" css is an ancestor of "child" | |
5142 | * @child: the css to be tested. | |
5143 | * @root: the css supporsed to be an ancestor of the child. | |
5144 | * | |
5145 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because | |
5146 | * this function reads css->id, the caller must hold rcu_read_lock(). | |
5147 | * But, considering usual usage, the csses should be valid objects after test. | |
5148 | * Assuming that the caller will do some action to the child if this returns | |
5149 | * returns true, the caller must take "child";s reference count. | |
5150 | * If "child" is valid object and this returns true, "root" is valid, too. | |
5151 | */ | |
5152 | ||
5153 | bool css_is_ancestor(struct cgroup_subsys_state *child, | |
5154 | const struct cgroup_subsys_state *root) | |
5155 | { | |
5156 | struct css_id *child_id; | |
5157 | struct css_id *root_id; | |
5158 | ||
5159 | child_id = rcu_dereference(child->id); | |
5160 | if (!child_id) | |
5161 | return false; | |
5162 | root_id = rcu_dereference(root->id); | |
5163 | if (!root_id) | |
5164 | return false; | |
5165 | if (child_id->depth < root_id->depth) | |
5166 | return false; | |
5167 | if (child_id->stack[root_id->depth] != root_id->id) | |
5168 | return false; | |
5169 | return true; | |
5170 | } | |
5171 | ||
5172 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) | |
5173 | { | |
5174 | struct css_id *id = css->id; | |
5175 | /* When this is called before css_id initialization, id can be NULL */ | |
5176 | if (!id) | |
5177 | return; | |
5178 | ||
5179 | BUG_ON(!ss->use_id); | |
5180 | ||
5181 | rcu_assign_pointer(id->css, NULL); | |
5182 | rcu_assign_pointer(css->id, NULL); | |
5183 | spin_lock(&ss->id_lock); | |
5184 | idr_remove(&ss->idr, id->id); | |
5185 | spin_unlock(&ss->id_lock); | |
5186 | kfree_rcu(id, rcu_head); | |
5187 | } | |
5188 | EXPORT_SYMBOL_GPL(free_css_id); | |
5189 | ||
5190 | /* | |
5191 | * This is called by init or create(). Then, calls to this function are | |
5192 | * always serialized (By cgroup_mutex() at create()). | |
5193 | */ | |
5194 | ||
5195 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
5196 | { | |
5197 | struct css_id *newid; | |
5198 | int myid, error, size; | |
5199 | ||
5200 | BUG_ON(!ss->use_id); | |
5201 | ||
5202 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
5203 | newid = kzalloc(size, GFP_KERNEL); | |
5204 | if (!newid) | |
5205 | return ERR_PTR(-ENOMEM); | |
5206 | /* get id */ | |
5207 | if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) { | |
5208 | error = -ENOMEM; | |
5209 | goto err_out; | |
5210 | } | |
5211 | spin_lock(&ss->id_lock); | |
5212 | /* Don't use 0. allocates an ID of 1-65535 */ | |
5213 | error = idr_get_new_above(&ss->idr, newid, 1, &myid); | |
5214 | spin_unlock(&ss->id_lock); | |
5215 | ||
5216 | /* Returns error when there are no free spaces for new ID.*/ | |
5217 | if (error) { | |
5218 | error = -ENOSPC; | |
5219 | goto err_out; | |
5220 | } | |
5221 | if (myid > CSS_ID_MAX) | |
5222 | goto remove_idr; | |
5223 | ||
5224 | newid->id = myid; | |
5225 | newid->depth = depth; | |
5226 | return newid; | |
5227 | remove_idr: | |
5228 | error = -ENOSPC; | |
5229 | spin_lock(&ss->id_lock); | |
5230 | idr_remove(&ss->idr, myid); | |
5231 | spin_unlock(&ss->id_lock); | |
5232 | err_out: | |
5233 | kfree(newid); | |
5234 | return ERR_PTR(error); | |
5235 | ||
5236 | } | |
5237 | ||
5238 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, | |
5239 | struct cgroup_subsys_state *rootcss) | |
5240 | { | |
5241 | struct css_id *newid; | |
5242 | ||
5243 | spin_lock_init(&ss->id_lock); | |
5244 | idr_init(&ss->idr); | |
5245 | ||
5246 | newid = get_new_cssid(ss, 0); | |
5247 | if (IS_ERR(newid)) | |
5248 | return PTR_ERR(newid); | |
5249 | ||
5250 | newid->stack[0] = newid->id; | |
5251 | newid->css = rootcss; | |
5252 | rootcss->id = newid; | |
5253 | return 0; | |
5254 | } | |
5255 | ||
5256 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
5257 | struct cgroup *child) | |
5258 | { | |
5259 | int subsys_id, i, depth = 0; | |
5260 | struct cgroup_subsys_state *parent_css, *child_css; | |
5261 | struct css_id *child_id, *parent_id; | |
5262 | ||
5263 | subsys_id = ss->subsys_id; | |
5264 | parent_css = parent->subsys[subsys_id]; | |
5265 | child_css = child->subsys[subsys_id]; | |
5266 | parent_id = parent_css->id; | |
5267 | depth = parent_id->depth + 1; | |
5268 | ||
5269 | child_id = get_new_cssid(ss, depth); | |
5270 | if (IS_ERR(child_id)) | |
5271 | return PTR_ERR(child_id); | |
5272 | ||
5273 | for (i = 0; i < depth; i++) | |
5274 | child_id->stack[i] = parent_id->stack[i]; | |
5275 | child_id->stack[depth] = child_id->id; | |
5276 | /* | |
5277 | * child_id->css pointer will be set after this cgroup is available | |
5278 | * see cgroup_populate_dir() | |
5279 | */ | |
5280 | rcu_assign_pointer(child_css->id, child_id); | |
5281 | ||
5282 | return 0; | |
5283 | } | |
5284 | ||
5285 | /** | |
5286 | * css_lookup - lookup css by id | |
5287 | * @ss: cgroup subsys to be looked into. | |
5288 | * @id: the id | |
5289 | * | |
5290 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
5291 | * NULL if not. Should be called under rcu_read_lock() | |
5292 | */ | |
5293 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
5294 | { | |
5295 | struct css_id *cssid = NULL; | |
5296 | ||
5297 | BUG_ON(!ss->use_id); | |
5298 | cssid = idr_find(&ss->idr, id); | |
5299 | ||
5300 | if (unlikely(!cssid)) | |
5301 | return NULL; | |
5302 | ||
5303 | return rcu_dereference(cssid->css); | |
5304 | } | |
5305 | EXPORT_SYMBOL_GPL(css_lookup); | |
5306 | ||
5307 | /** | |
5308 | * css_get_next - lookup next cgroup under specified hierarchy. | |
5309 | * @ss: pointer to subsystem | |
5310 | * @id: current position of iteration. | |
5311 | * @root: pointer to css. search tree under this. | |
5312 | * @foundid: position of found object. | |
5313 | * | |
5314 | * Search next css under the specified hierarchy of rootid. Calling under | |
5315 | * rcu_read_lock() is necessary. Returns NULL if it reaches the end. | |
5316 | */ | |
5317 | struct cgroup_subsys_state * | |
5318 | css_get_next(struct cgroup_subsys *ss, int id, | |
5319 | struct cgroup_subsys_state *root, int *foundid) | |
5320 | { | |
5321 | struct cgroup_subsys_state *ret = NULL; | |
5322 | struct css_id *tmp; | |
5323 | int tmpid; | |
5324 | int rootid = css_id(root); | |
5325 | int depth = css_depth(root); | |
5326 | ||
5327 | if (!rootid) | |
5328 | return NULL; | |
5329 | ||
5330 | BUG_ON(!ss->use_id); | |
5331 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
5332 | ||
5333 | /* fill start point for scan */ | |
5334 | tmpid = id; | |
5335 | while (1) { | |
5336 | /* | |
5337 | * scan next entry from bitmap(tree), tmpid is updated after | |
5338 | * idr_get_next(). | |
5339 | */ | |
5340 | tmp = idr_get_next(&ss->idr, &tmpid); | |
5341 | if (!tmp) | |
5342 | break; | |
5343 | if (tmp->depth >= depth && tmp->stack[depth] == rootid) { | |
5344 | ret = rcu_dereference(tmp->css); | |
5345 | if (ret) { | |
5346 | *foundid = tmpid; | |
5347 | break; | |
5348 | } | |
5349 | } | |
5350 | /* continue to scan from next id */ | |
5351 | tmpid = tmpid + 1; | |
5352 | } | |
5353 | return ret; | |
5354 | } | |
5355 | ||
5356 | /* | |
5357 | * get corresponding css from file open on cgroupfs directory | |
5358 | */ | |
5359 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) | |
5360 | { | |
5361 | struct cgroup *cgrp; | |
5362 | struct inode *inode; | |
5363 | struct cgroup_subsys_state *css; | |
5364 | ||
5365 | inode = f->f_dentry->d_inode; | |
5366 | /* check in cgroup filesystem dir */ | |
5367 | if (inode->i_op != &cgroup_dir_inode_operations) | |
5368 | return ERR_PTR(-EBADF); | |
5369 | ||
5370 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) | |
5371 | return ERR_PTR(-EINVAL); | |
5372 | ||
5373 | /* get cgroup */ | |
5374 | cgrp = __d_cgrp(f->f_dentry); | |
5375 | css = cgrp->subsys[id]; | |
5376 | return css ? css : ERR_PTR(-ENOENT); | |
5377 | } | |
5378 | ||
5379 | #ifdef CONFIG_CGROUP_DEBUG | |
5380 | static struct cgroup_subsys_state *debug_create(struct cgroup *cont) | |
5381 | { | |
5382 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5383 | ||
5384 | if (!css) | |
5385 | return ERR_PTR(-ENOMEM); | |
5386 | ||
5387 | return css; | |
5388 | } | |
5389 | ||
5390 | static void debug_destroy(struct cgroup *cont) | |
5391 | { | |
5392 | kfree(cont->subsys[debug_subsys_id]); | |
5393 | } | |
5394 | ||
5395 | static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) | |
5396 | { | |
5397 | return atomic_read(&cont->count); | |
5398 | } | |
5399 | ||
5400 | static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) | |
5401 | { | |
5402 | return cgroup_task_count(cont); | |
5403 | } | |
5404 | ||
5405 | static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) | |
5406 | { | |
5407 | return (u64)(unsigned long)current->cgroups; | |
5408 | } | |
5409 | ||
5410 | static u64 current_css_set_refcount_read(struct cgroup *cont, | |
5411 | struct cftype *cft) | |
5412 | { | |
5413 | u64 count; | |
5414 | ||
5415 | rcu_read_lock(); | |
5416 | count = atomic_read(¤t->cgroups->refcount); | |
5417 | rcu_read_unlock(); | |
5418 | return count; | |
5419 | } | |
5420 | ||
5421 | static int current_css_set_cg_links_read(struct cgroup *cont, | |
5422 | struct cftype *cft, | |
5423 | struct seq_file *seq) | |
5424 | { | |
5425 | struct cg_cgroup_link *link; | |
5426 | struct css_set *cg; | |
5427 | ||
5428 | read_lock(&css_set_lock); | |
5429 | rcu_read_lock(); | |
5430 | cg = rcu_dereference(current->cgroups); | |
5431 | list_for_each_entry(link, &cg->cg_links, cg_link_list) { | |
5432 | struct cgroup *c = link->cgrp; | |
5433 | const char *name; | |
5434 | ||
5435 | if (c->dentry) | |
5436 | name = c->dentry->d_name.name; | |
5437 | else | |
5438 | name = "?"; | |
5439 | seq_printf(seq, "Root %d group %s\n", | |
5440 | c->root->hierarchy_id, name); | |
5441 | } | |
5442 | rcu_read_unlock(); | |
5443 | read_unlock(&css_set_lock); | |
5444 | return 0; | |
5445 | } | |
5446 | ||
5447 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
5448 | static int cgroup_css_links_read(struct cgroup *cont, | |
5449 | struct cftype *cft, | |
5450 | struct seq_file *seq) | |
5451 | { | |
5452 | struct cg_cgroup_link *link; | |
5453 | ||
5454 | read_lock(&css_set_lock); | |
5455 | list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { | |
5456 | struct css_set *cg = link->cg; | |
5457 | struct task_struct *task; | |
5458 | int count = 0; | |
5459 | seq_printf(seq, "css_set %p\n", cg); | |
5460 | list_for_each_entry(task, &cg->tasks, cg_list) { | |
5461 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { | |
5462 | seq_puts(seq, " ...\n"); | |
5463 | break; | |
5464 | } else { | |
5465 | seq_printf(seq, " task %d\n", | |
5466 | task_pid_vnr(task)); | |
5467 | } | |
5468 | } | |
5469 | } | |
5470 | read_unlock(&css_set_lock); | |
5471 | return 0; | |
5472 | } | |
5473 | ||
5474 | static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) | |
5475 | { | |
5476 | return test_bit(CGRP_RELEASABLE, &cgrp->flags); | |
5477 | } | |
5478 | ||
5479 | static struct cftype debug_files[] = { | |
5480 | { | |
5481 | .name = "cgroup_refcount", | |
5482 | .read_u64 = cgroup_refcount_read, | |
5483 | }, | |
5484 | { | |
5485 | .name = "taskcount", | |
5486 | .read_u64 = debug_taskcount_read, | |
5487 | }, | |
5488 | ||
5489 | { | |
5490 | .name = "current_css_set", | |
5491 | .read_u64 = current_css_set_read, | |
5492 | }, | |
5493 | ||
5494 | { | |
5495 | .name = "current_css_set_refcount", | |
5496 | .read_u64 = current_css_set_refcount_read, | |
5497 | }, | |
5498 | ||
5499 | { | |
5500 | .name = "current_css_set_cg_links", | |
5501 | .read_seq_string = current_css_set_cg_links_read, | |
5502 | }, | |
5503 | ||
5504 | { | |
5505 | .name = "cgroup_css_links", | |
5506 | .read_seq_string = cgroup_css_links_read, | |
5507 | }, | |
5508 | ||
5509 | { | |
5510 | .name = "releasable", | |
5511 | .read_u64 = releasable_read, | |
5512 | }, | |
5513 | ||
5514 | { } /* terminate */ | |
5515 | }; | |
5516 | ||
5517 | struct cgroup_subsys debug_subsys = { | |
5518 | .name = "debug", | |
5519 | .create = debug_create, | |
5520 | .destroy = debug_destroy, | |
5521 | .subsys_id = debug_subsys_id, | |
5522 | .base_cftypes = debug_files, | |
5523 | }; | |
5524 | #endif /* CONFIG_CGROUP_DEBUG */ |