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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/ctype.h> |
31 | #include <linux/errno.h> |
32 | #include <linux/fs.h> |
33 | #include <linux/kernel.h> |
34 | #include <linux/list.h> |
35 | #include <linux/mm.h> |
36 | #include <linux/mutex.h> |
37 | #include <linux/mount.h> |
38 | #include <linux/pagemap.h> |
39 | #include <linux/proc_fs.h> |
40 | #include <linux/rcupdate.h> |
41 | #include <linux/sched.h> |
42 | #include <linux/backing-dev.h> |
43 | #include <linux/seq_file.h> |
44 | #include <linux/slab.h> |
45 | #include <linux/magic.h> |
46 | #include <linux/spinlock.h> |
47 | #include <linux/string.h> |
48 | #include <linux/sort.h> |
49 | #include <linux/kmod.h> |
50 | #include <linux/module.h> |
51 | #include <linux/delayacct.h> |
52 | #include <linux/cgroupstats.h> |
53 | #include <linux/hash.h> |
54 | #include <linux/namei.h> |
55 | #include <linux/pid_namespace.h> |
56 | #include <linux/idr.h> |
57 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
58 | #include <linux/eventfd.h> |
59 | #include <linux/poll.h> |
60 | |
61 | #include <asm/atomic.h> |
62 | |
63 | static DEFINE_MUTEX(cgroup_mutex); |
64 | |
65 | /* |
66 | * Generate an array of cgroup subsystem pointers. At boot time, this is |
67 | * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are |
68 | * registered after that. The mutable section of this array is protected by |
69 | * cgroup_mutex. |
70 | */ |
71 | #define SUBSYS(_x) &_x ## _subsys, |
72 | static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { |
73 | #include <linux/cgroup_subsys.h> |
74 | }; |
75 | |
76 | #define MAX_CGROUP_ROOT_NAMELEN 64 |
77 | |
78 | /* |
79 | * A cgroupfs_root represents the root of a cgroup hierarchy, |
80 | * and may be associated with a superblock to form an active |
81 | * hierarchy |
82 | */ |
83 | struct cgroupfs_root { |
84 | struct super_block *sb; |
85 | |
86 | /* |
87 | * The bitmask of subsystems intended to be attached to this |
88 | * hierarchy |
89 | */ |
90 | unsigned long subsys_bits; |
91 | |
92 | /* Unique id for this hierarchy. */ |
93 | int hierarchy_id; |
94 | |
95 | /* The bitmask of subsystems currently attached to this hierarchy */ |
96 | unsigned long actual_subsys_bits; |
97 | |
98 | /* A list running through the attached subsystems */ |
99 | struct list_head subsys_list; |
100 | |
101 | /* The root cgroup for this hierarchy */ |
102 | struct cgroup top_cgroup; |
103 | |
104 | /* Tracks how many cgroups are currently defined in hierarchy.*/ |
105 | int number_of_cgroups; |
106 | |
107 | /* A list running through the active hierarchies */ |
108 | struct list_head root_list; |
109 | |
110 | /* Hierarchy-specific flags */ |
111 | unsigned long flags; |
112 | |
113 | /* The path to use for release notifications. */ |
114 | char release_agent_path[PATH_MAX]; |
115 | |
116 | /* The name for this hierarchy - may be empty */ |
117 | char name[MAX_CGROUP_ROOT_NAMELEN]; |
118 | }; |
119 | |
120 | /* |
121 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the |
122 | * subsystems that are otherwise unattached - it never has more than a |
123 | * single cgroup, and all tasks are part of that cgroup. |
124 | */ |
125 | static struct cgroupfs_root rootnode; |
126 | |
127 | /* |
128 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when |
129 | * cgroup_subsys->use_id != 0. |
130 | */ |
131 | #define CSS_ID_MAX (65535) |
132 | struct css_id { |
133 | /* |
134 | * The css to which this ID points. This pointer is set to valid value |
135 | * after cgroup is populated. If cgroup is removed, this will be NULL. |
136 | * This pointer is expected to be RCU-safe because destroy() |
137 | * is called after synchronize_rcu(). But for safe use, css_is_removed() |
138 | * css_tryget() should be used for avoiding race. |
139 | */ |
140 | struct cgroup_subsys_state __rcu *css; |
141 | /* |
142 | * ID of this css. |
143 | */ |
144 | unsigned short id; |
145 | /* |
146 | * Depth in hierarchy which this ID belongs to. |
147 | */ |
148 | unsigned short depth; |
149 | /* |
150 | * ID is freed by RCU. (and lookup routine is RCU safe.) |
151 | */ |
152 | struct rcu_head rcu_head; |
153 | /* |
154 | * Hierarchy of CSS ID belongs to. |
155 | */ |
156 | unsigned short stack[0]; /* Array of Length (depth+1) */ |
157 | }; |
158 | |
159 | /* |
160 | * cgroup_event represents events which userspace want to receive. |
161 | */ |
162 | struct cgroup_event { |
163 | /* |
164 | * Cgroup which the event belongs to. |
165 | */ |
166 | struct cgroup *cgrp; |
167 | /* |
168 | * Control file which the event associated. |
169 | */ |
170 | struct cftype *cft; |
171 | /* |
172 | * eventfd to signal userspace about the event. |
173 | */ |
174 | struct eventfd_ctx *eventfd; |
175 | /* |
176 | * Each of these stored in a list by the cgroup. |
177 | */ |
178 | struct list_head list; |
179 | /* |
180 | * All fields below needed to unregister event when |
181 | * userspace closes eventfd. |
182 | */ |
183 | poll_table pt; |
184 | wait_queue_head_t *wqh; |
185 | wait_queue_t wait; |
186 | struct work_struct remove; |
187 | }; |
188 | |
189 | /* The list of hierarchy roots */ |
190 | |
191 | static LIST_HEAD(roots); |
192 | static int root_count; |
193 | |
194 | static DEFINE_IDA(hierarchy_ida); |
195 | static int next_hierarchy_id; |
196 | static DEFINE_SPINLOCK(hierarchy_id_lock); |
197 | |
198 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ |
199 | #define dummytop (&rootnode.top_cgroup) |
200 | |
201 | /* This flag indicates whether tasks in the fork and exit paths should |
202 | * check for fork/exit handlers to call. This avoids us having to do |
203 | * extra work in the fork/exit path if none of the subsystems need to |
204 | * be called. |
205 | */ |
206 | static int need_forkexit_callback __read_mostly; |
207 | |
208 | #ifdef CONFIG_PROVE_LOCKING |
209 | int cgroup_lock_is_held(void) |
210 | { |
211 | return lockdep_is_held(&cgroup_mutex); |
212 | } |
213 | #else /* #ifdef CONFIG_PROVE_LOCKING */ |
214 | int cgroup_lock_is_held(void) |
215 | { |
216 | return mutex_is_locked(&cgroup_mutex); |
217 | } |
218 | #endif /* #else #ifdef CONFIG_PROVE_LOCKING */ |
219 | |
220 | EXPORT_SYMBOL_GPL(cgroup_lock_is_held); |
221 | |
222 | /* convenient tests for these bits */ |
223 | inline int cgroup_is_removed(const struct cgroup *cgrp) |
224 | { |
225 | return test_bit(CGRP_REMOVED, &cgrp->flags); |
226 | } |
227 | |
228 | /* bits in struct cgroupfs_root flags field */ |
229 | enum { |
230 | ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ |
231 | }; |
232 | |
233 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
234 | { |
235 | const int bits = |
236 | (1 << CGRP_RELEASABLE) | |
237 | (1 << CGRP_NOTIFY_ON_RELEASE); |
238 | return (cgrp->flags & bits) == bits; |
239 | } |
240 | |
241 | static int notify_on_release(const struct cgroup *cgrp) |
242 | { |
243 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
244 | } |
245 | |
246 | static int clone_children(const struct cgroup *cgrp) |
247 | { |
248 | return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); |
249 | } |
250 | |
251 | /* |
252 | * for_each_subsys() allows you to iterate on each subsystem attached to |
253 | * an active hierarchy |
254 | */ |
255 | #define for_each_subsys(_root, _ss) \ |
256 | list_for_each_entry(_ss, &_root->subsys_list, sibling) |
257 | |
258 | /* for_each_active_root() allows you to iterate across the active hierarchies */ |
259 | #define for_each_active_root(_root) \ |
260 | list_for_each_entry(_root, &roots, root_list) |
261 | |
262 | /* the list of cgroups eligible for automatic release. Protected by |
263 | * release_list_lock */ |
264 | static LIST_HEAD(release_list); |
265 | static DEFINE_SPINLOCK(release_list_lock); |
266 | static void cgroup_release_agent(struct work_struct *work); |
267 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); |
268 | static void check_for_release(struct cgroup *cgrp); |
269 | |
270 | /* Link structure for associating css_set objects with cgroups */ |
271 | struct cg_cgroup_link { |
272 | /* |
273 | * List running through cg_cgroup_links associated with a |
274 | * cgroup, anchored on cgroup->css_sets |
275 | */ |
276 | struct list_head cgrp_link_list; |
277 | struct cgroup *cgrp; |
278 | /* |
279 | * List running through cg_cgroup_links pointing at a |
280 | * single css_set object, anchored on css_set->cg_links |
281 | */ |
282 | struct list_head cg_link_list; |
283 | struct css_set *cg; |
284 | }; |
285 | |
286 | /* The default css_set - used by init and its children prior to any |
287 | * hierarchies being mounted. It contains a pointer to the root state |
288 | * for each subsystem. Also used to anchor the list of css_sets. Not |
289 | * reference-counted, to improve performance when child cgroups |
290 | * haven't been created. |
291 | */ |
292 | |
293 | static struct css_set init_css_set; |
294 | static struct cg_cgroup_link init_css_set_link; |
295 | |
296 | static int cgroup_init_idr(struct cgroup_subsys *ss, |
297 | struct cgroup_subsys_state *css); |
298 | |
299 | /* css_set_lock protects the list of css_set objects, and the |
300 | * chain of tasks off each css_set. Nests outside task->alloc_lock |
301 | * due to cgroup_iter_start() */ |
302 | static DEFINE_RWLOCK(css_set_lock); |
303 | static int css_set_count; |
304 | |
305 | /* |
306 | * hash table for cgroup groups. This improves the performance to find |
307 | * an existing css_set. This hash doesn't (currently) take into |
308 | * account cgroups in empty hierarchies. |
309 | */ |
310 | #define CSS_SET_HASH_BITS 7 |
311 | #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) |
312 | static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; |
313 | |
314 | static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) |
315 | { |
316 | int i; |
317 | int index; |
318 | unsigned long tmp = 0UL; |
319 | |
320 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) |
321 | tmp += (unsigned long)css[i]; |
322 | tmp = (tmp >> 16) ^ tmp; |
323 | |
324 | index = hash_long(tmp, CSS_SET_HASH_BITS); |
325 | |
326 | return &css_set_table[index]; |
327 | } |
328 | |
329 | static void free_css_set_rcu(struct rcu_head *obj) |
330 | { |
331 | struct css_set *cg = container_of(obj, struct css_set, rcu_head); |
332 | kfree(cg); |
333 | } |
334 | |
335 | /* We don't maintain the lists running through each css_set to its |
336 | * task until after the first call to cgroup_iter_start(). This |
337 | * reduces the fork()/exit() overhead for people who have cgroups |
338 | * compiled into their kernel but not actually in use */ |
339 | static int use_task_css_set_links __read_mostly; |
340 | |
341 | static void __put_css_set(struct css_set *cg, int taskexit) |
342 | { |
343 | struct cg_cgroup_link *link; |
344 | struct cg_cgroup_link *saved_link; |
345 | /* |
346 | * Ensure that the refcount doesn't hit zero while any readers |
347 | * can see it. Similar to atomic_dec_and_lock(), but for an |
348 | * rwlock |
349 | */ |
350 | if (atomic_add_unless(&cg->refcount, -1, 1)) |
351 | return; |
352 | write_lock(&css_set_lock); |
353 | if (!atomic_dec_and_test(&cg->refcount)) { |
354 | write_unlock(&css_set_lock); |
355 | return; |
356 | } |
357 | |
358 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
359 | hlist_del(&cg->hlist); |
360 | css_set_count--; |
361 | |
362 | list_for_each_entry_safe(link, saved_link, &cg->cg_links, |
363 | cg_link_list) { |
364 | struct cgroup *cgrp = link->cgrp; |
365 | list_del(&link->cg_link_list); |
366 | list_del(&link->cgrp_link_list); |
367 | if (atomic_dec_and_test(&cgrp->count) && |
368 | notify_on_release(cgrp)) { |
369 | if (taskexit) |
370 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
371 | check_for_release(cgrp); |
372 | } |
373 | |
374 | kfree(link); |
375 | } |
376 | |
377 | write_unlock(&css_set_lock); |
378 | call_rcu(&cg->rcu_head, free_css_set_rcu); |
379 | } |
380 | |
381 | /* |
382 | * refcounted get/put for css_set objects |
383 | */ |
384 | static inline void get_css_set(struct css_set *cg) |
385 | { |
386 | atomic_inc(&cg->refcount); |
387 | } |
388 | |
389 | static inline void put_css_set(struct css_set *cg) |
390 | { |
391 | __put_css_set(cg, 0); |
392 | } |
393 | |
394 | static inline void put_css_set_taskexit(struct css_set *cg) |
395 | { |
396 | __put_css_set(cg, 1); |
397 | } |
398 | |
399 | /* |
400 | * compare_css_sets - helper function for find_existing_css_set(). |
401 | * @cg: candidate css_set being tested |
402 | * @old_cg: existing css_set for a task |
403 | * @new_cgrp: cgroup that's being entered by the task |
404 | * @template: desired set of css pointers in css_set (pre-calculated) |
405 | * |
406 | * Returns true if "cg" matches "old_cg" except for the hierarchy |
407 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
408 | */ |
409 | static bool compare_css_sets(struct css_set *cg, |
410 | struct css_set *old_cg, |
411 | struct cgroup *new_cgrp, |
412 | struct cgroup_subsys_state *template[]) |
413 | { |
414 | struct list_head *l1, *l2; |
415 | |
416 | if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { |
417 | /* Not all subsystems matched */ |
418 | return false; |
419 | } |
420 | |
421 | /* |
422 | * Compare cgroup pointers in order to distinguish between |
423 | * different cgroups in heirarchies with no subsystems. We |
424 | * could get by with just this check alone (and skip the |
425 | * memcmp above) but on most setups the memcmp check will |
426 | * avoid the need for this more expensive check on almost all |
427 | * candidates. |
428 | */ |
429 | |
430 | l1 = &cg->cg_links; |
431 | l2 = &old_cg->cg_links; |
432 | while (1) { |
433 | struct cg_cgroup_link *cgl1, *cgl2; |
434 | struct cgroup *cg1, *cg2; |
435 | |
436 | l1 = l1->next; |
437 | l2 = l2->next; |
438 | /* See if we reached the end - both lists are equal length. */ |
439 | if (l1 == &cg->cg_links) { |
440 | BUG_ON(l2 != &old_cg->cg_links); |
441 | break; |
442 | } else { |
443 | BUG_ON(l2 == &old_cg->cg_links); |
444 | } |
445 | /* Locate the cgroups associated with these links. */ |
446 | cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); |
447 | cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); |
448 | cg1 = cgl1->cgrp; |
449 | cg2 = cgl2->cgrp; |
450 | /* Hierarchies should be linked in the same order. */ |
451 | BUG_ON(cg1->root != cg2->root); |
452 | |
453 | /* |
454 | * If this hierarchy is the hierarchy of the cgroup |
455 | * that's changing, then we need to check that this |
456 | * css_set points to the new cgroup; if it's any other |
457 | * hierarchy, then this css_set should point to the |
458 | * same cgroup as the old css_set. |
459 | */ |
460 | if (cg1->root == new_cgrp->root) { |
461 | if (cg1 != new_cgrp) |
462 | return false; |
463 | } else { |
464 | if (cg1 != cg2) |
465 | return false; |
466 | } |
467 | } |
468 | return true; |
469 | } |
470 | |
471 | /* |
472 | * find_existing_css_set() is a helper for |
473 | * find_css_set(), and checks to see whether an existing |
474 | * css_set is suitable. |
475 | * |
476 | * oldcg: the cgroup group that we're using before the cgroup |
477 | * transition |
478 | * |
479 | * cgrp: the cgroup that we're moving into |
480 | * |
481 | * template: location in which to build the desired set of subsystem |
482 | * state objects for the new cgroup group |
483 | */ |
484 | static struct css_set *find_existing_css_set( |
485 | struct css_set *oldcg, |
486 | struct cgroup *cgrp, |
487 | struct cgroup_subsys_state *template[]) |
488 | { |
489 | int i; |
490 | struct cgroupfs_root *root = cgrp->root; |
491 | struct hlist_head *hhead; |
492 | struct hlist_node *node; |
493 | struct css_set *cg; |
494 | |
495 | /* |
496 | * Build the set of subsystem state objects that we want to see in the |
497 | * new css_set. while subsystems can change globally, the entries here |
498 | * won't change, so no need for locking. |
499 | */ |
500 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
501 | if (root->subsys_bits & (1UL << i)) { |
502 | /* Subsystem is in this hierarchy. So we want |
503 | * the subsystem state from the new |
504 | * cgroup */ |
505 | template[i] = cgrp->subsys[i]; |
506 | } else { |
507 | /* Subsystem is not in this hierarchy, so we |
508 | * don't want to change the subsystem state */ |
509 | template[i] = oldcg->subsys[i]; |
510 | } |
511 | } |
512 | |
513 | hhead = css_set_hash(template); |
514 | hlist_for_each_entry(cg, node, hhead, hlist) { |
515 | if (!compare_css_sets(cg, oldcg, cgrp, template)) |
516 | continue; |
517 | |
518 | /* This css_set matches what we need */ |
519 | return cg; |
520 | } |
521 | |
522 | /* No existing cgroup group matched */ |
523 | return NULL; |
524 | } |
525 | |
526 | static void free_cg_links(struct list_head *tmp) |
527 | { |
528 | struct cg_cgroup_link *link; |
529 | struct cg_cgroup_link *saved_link; |
530 | |
531 | list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { |
532 | list_del(&link->cgrp_link_list); |
533 | kfree(link); |
534 | } |
535 | } |
536 | |
537 | /* |
538 | * allocate_cg_links() allocates "count" cg_cgroup_link structures |
539 | * and chains them on tmp through their cgrp_link_list fields. Returns 0 on |
540 | * success or a negative error |
541 | */ |
542 | static int allocate_cg_links(int count, struct list_head *tmp) |
543 | { |
544 | struct cg_cgroup_link *link; |
545 | int i; |
546 | INIT_LIST_HEAD(tmp); |
547 | for (i = 0; i < count; i++) { |
548 | link = kmalloc(sizeof(*link), GFP_KERNEL); |
549 | if (!link) { |
550 | free_cg_links(tmp); |
551 | return -ENOMEM; |
552 | } |
553 | list_add(&link->cgrp_link_list, tmp); |
554 | } |
555 | return 0; |
556 | } |
557 | |
558 | /** |
559 | * link_css_set - a helper function to link a css_set to a cgroup |
560 | * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() |
561 | * @cg: the css_set to be linked |
562 | * @cgrp: the destination cgroup |
563 | */ |
564 | static void link_css_set(struct list_head *tmp_cg_links, |
565 | struct css_set *cg, struct cgroup *cgrp) |
566 | { |
567 | struct cg_cgroup_link *link; |
568 | |
569 | BUG_ON(list_empty(tmp_cg_links)); |
570 | link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, |
571 | cgrp_link_list); |
572 | link->cg = cg; |
573 | link->cgrp = cgrp; |
574 | atomic_inc(&cgrp->count); |
575 | list_move(&link->cgrp_link_list, &cgrp->css_sets); |
576 | /* |
577 | * Always add links to the tail of the list so that the list |
578 | * is sorted by order of hierarchy creation |
579 | */ |
580 | list_add_tail(&link->cg_link_list, &cg->cg_links); |
581 | } |
582 | |
583 | /* |
584 | * find_css_set() takes an existing cgroup group and a |
585 | * cgroup object, and returns a css_set object that's |
586 | * equivalent to the old group, but with the given cgroup |
587 | * substituted into the appropriate hierarchy. Must be called with |
588 | * cgroup_mutex held |
589 | */ |
590 | static struct css_set *find_css_set( |
591 | struct css_set *oldcg, struct cgroup *cgrp) |
592 | { |
593 | struct css_set *res; |
594 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; |
595 | |
596 | struct list_head tmp_cg_links; |
597 | |
598 | struct hlist_head *hhead; |
599 | struct cg_cgroup_link *link; |
600 | |
601 | /* First see if we already have a cgroup group that matches |
602 | * the desired set */ |
603 | read_lock(&css_set_lock); |
604 | res = find_existing_css_set(oldcg, cgrp, template); |
605 | if (res) |
606 | get_css_set(res); |
607 | read_unlock(&css_set_lock); |
608 | |
609 | if (res) |
610 | return res; |
611 | |
612 | res = kmalloc(sizeof(*res), GFP_KERNEL); |
613 | if (!res) |
614 | return NULL; |
615 | |
616 | /* Allocate all the cg_cgroup_link objects that we'll need */ |
617 | if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { |
618 | kfree(res); |
619 | return NULL; |
620 | } |
621 | |
622 | atomic_set(&res->refcount, 1); |
623 | INIT_LIST_HEAD(&res->cg_links); |
624 | INIT_LIST_HEAD(&res->tasks); |
625 | INIT_HLIST_NODE(&res->hlist); |
626 | |
627 | /* Copy the set of subsystem state objects generated in |
628 | * find_existing_css_set() */ |
629 | memcpy(res->subsys, template, sizeof(res->subsys)); |
630 | |
631 | write_lock(&css_set_lock); |
632 | /* Add reference counts and links from the new css_set. */ |
633 | list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { |
634 | struct cgroup *c = link->cgrp; |
635 | if (c->root == cgrp->root) |
636 | c = cgrp; |
637 | link_css_set(&tmp_cg_links, res, c); |
638 | } |
639 | |
640 | BUG_ON(!list_empty(&tmp_cg_links)); |
641 | |
642 | css_set_count++; |
643 | |
644 | /* Add this cgroup group to the hash table */ |
645 | hhead = css_set_hash(res->subsys); |
646 | hlist_add_head(&res->hlist, hhead); |
647 | |
648 | write_unlock(&css_set_lock); |
649 | |
650 | return res; |
651 | } |
652 | |
653 | /* |
654 | * Return the cgroup for "task" from the given hierarchy. Must be |
655 | * called with cgroup_mutex held. |
656 | */ |
657 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, |
658 | struct cgroupfs_root *root) |
659 | { |
660 | struct css_set *css; |
661 | struct cgroup *res = NULL; |
662 | |
663 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
664 | read_lock(&css_set_lock); |
665 | /* |
666 | * No need to lock the task - since we hold cgroup_mutex the |
667 | * task can't change groups, so the only thing that can happen |
668 | * is that it exits and its css is set back to init_css_set. |
669 | */ |
670 | css = task->cgroups; |
671 | if (css == &init_css_set) { |
672 | res = &root->top_cgroup; |
673 | } else { |
674 | struct cg_cgroup_link *link; |
675 | list_for_each_entry(link, &css->cg_links, cg_link_list) { |
676 | struct cgroup *c = link->cgrp; |
677 | if (c->root == root) { |
678 | res = c; |
679 | break; |
680 | } |
681 | } |
682 | } |
683 | read_unlock(&css_set_lock); |
684 | BUG_ON(!res); |
685 | return res; |
686 | } |
687 | |
688 | /* |
689 | * There is one global cgroup mutex. We also require taking |
690 | * task_lock() when dereferencing a task's cgroup subsys pointers. |
691 | * See "The task_lock() exception", at the end of this comment. |
692 | * |
693 | * A task must hold cgroup_mutex to modify cgroups. |
694 | * |
695 | * Any task can increment and decrement the count field without lock. |
696 | * So in general, code holding cgroup_mutex can't rely on the count |
697 | * field not changing. However, if the count goes to zero, then only |
698 | * cgroup_attach_task() can increment it again. Because a count of zero |
699 | * means that no tasks are currently attached, therefore there is no |
700 | * way a task attached to that cgroup can fork (the other way to |
701 | * increment the count). So code holding cgroup_mutex can safely |
702 | * assume that if the count is zero, it will stay zero. Similarly, if |
703 | * a task holds cgroup_mutex on a cgroup with zero count, it |
704 | * knows that the cgroup won't be removed, as cgroup_rmdir() |
705 | * needs that mutex. |
706 | * |
707 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
708 | * (usually) take cgroup_mutex. These are the two most performance |
709 | * critical pieces of code here. The exception occurs on cgroup_exit(), |
710 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex |
711 | * is taken, and if the cgroup count is zero, a usermode call made |
712 | * to the release agent with the name of the cgroup (path relative to |
713 | * the root of cgroup file system) as the argument. |
714 | * |
715 | * A cgroup can only be deleted if both its 'count' of using tasks |
716 | * is zero, and its list of 'children' cgroups is empty. Since all |
717 | * tasks in the system use _some_ cgroup, and since there is always at |
718 | * least one task in the system (init, pid == 1), therefore, top_cgroup |
719 | * always has either children cgroups and/or using tasks. So we don't |
720 | * need a special hack to ensure that top_cgroup cannot be deleted. |
721 | * |
722 | * The task_lock() exception |
723 | * |
724 | * The need for this exception arises from the action of |
725 | * cgroup_attach_task(), which overwrites one tasks cgroup pointer with |
726 | * another. It does so using cgroup_mutex, however there are |
727 | * several performance critical places that need to reference |
728 | * task->cgroup without the expense of grabbing a system global |
729 | * mutex. Therefore except as noted below, when dereferencing or, as |
730 | * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use |
731 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
732 | * the task_struct routinely used for such matters. |
733 | * |
734 | * P.S. One more locking exception. RCU is used to guard the |
735 | * update of a tasks cgroup pointer by cgroup_attach_task() |
736 | */ |
737 | |
738 | /** |
739 | * cgroup_lock - lock out any changes to cgroup structures |
740 | * |
741 | */ |
742 | void cgroup_lock(void) |
743 | { |
744 | mutex_lock(&cgroup_mutex); |
745 | } |
746 | EXPORT_SYMBOL_GPL(cgroup_lock); |
747 | |
748 | /** |
749 | * cgroup_unlock - release lock on cgroup changes |
750 | * |
751 | * Undo the lock taken in a previous cgroup_lock() call. |
752 | */ |
753 | void cgroup_unlock(void) |
754 | { |
755 | mutex_unlock(&cgroup_mutex); |
756 | } |
757 | EXPORT_SYMBOL_GPL(cgroup_unlock); |
758 | |
759 | /* |
760 | * A couple of forward declarations required, due to cyclic reference loop: |
761 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> |
762 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations |
763 | * -> cgroup_mkdir. |
764 | */ |
765 | |
766 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode); |
767 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, struct nameidata *); |
768 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
769 | static int cgroup_populate_dir(struct cgroup *cgrp); |
770 | static const struct inode_operations cgroup_dir_inode_operations; |
771 | static const struct file_operations proc_cgroupstats_operations; |
772 | |
773 | static struct backing_dev_info cgroup_backing_dev_info = { |
774 | .name = "cgroup", |
775 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
776 | }; |
777 | |
778 | static int alloc_css_id(struct cgroup_subsys *ss, |
779 | struct cgroup *parent, struct cgroup *child); |
780 | |
781 | static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb) |
782 | { |
783 | struct inode *inode = new_inode(sb); |
784 | |
785 | if (inode) { |
786 | inode->i_ino = get_next_ino(); |
787 | inode->i_mode = mode; |
788 | inode->i_uid = current_fsuid(); |
789 | inode->i_gid = current_fsgid(); |
790 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
791 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; |
792 | } |
793 | return inode; |
794 | } |
795 | |
796 | /* |
797 | * Call subsys's pre_destroy handler. |
798 | * This is called before css refcnt check. |
799 | */ |
800 | static int cgroup_call_pre_destroy(struct cgroup *cgrp) |
801 | { |
802 | struct cgroup_subsys *ss; |
803 | int ret = 0; |
804 | |
805 | for_each_subsys(cgrp->root, ss) |
806 | if (ss->pre_destroy) { |
807 | ret = ss->pre_destroy(ss, cgrp); |
808 | if (ret) |
809 | break; |
810 | } |
811 | |
812 | return ret; |
813 | } |
814 | |
815 | static void free_cgroup_rcu(struct rcu_head *obj) |
816 | { |
817 | struct cgroup *cgrp = container_of(obj, struct cgroup, rcu_head); |
818 | |
819 | kfree(cgrp); |
820 | } |
821 | |
822 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
823 | { |
824 | /* is dentry a directory ? if so, kfree() associated cgroup */ |
825 | if (S_ISDIR(inode->i_mode)) { |
826 | struct cgroup *cgrp = dentry->d_fsdata; |
827 | struct cgroup_subsys *ss; |
828 | BUG_ON(!(cgroup_is_removed(cgrp))); |
829 | /* It's possible for external users to be holding css |
830 | * reference counts on a cgroup; css_put() needs to |
831 | * be able to access the cgroup after decrementing |
832 | * the reference count in order to know if it needs to |
833 | * queue the cgroup to be handled by the release |
834 | * agent */ |
835 | synchronize_rcu(); |
836 | |
837 | mutex_lock(&cgroup_mutex); |
838 | /* |
839 | * Release the subsystem state objects. |
840 | */ |
841 | for_each_subsys(cgrp->root, ss) |
842 | ss->destroy(ss, cgrp); |
843 | |
844 | cgrp->root->number_of_cgroups--; |
845 | mutex_unlock(&cgroup_mutex); |
846 | |
847 | /* |
848 | * Drop the active superblock reference that we took when we |
849 | * created the cgroup |
850 | */ |
851 | deactivate_super(cgrp->root->sb); |
852 | |
853 | /* |
854 | * if we're getting rid of the cgroup, refcount should ensure |
855 | * that there are no pidlists left. |
856 | */ |
857 | BUG_ON(!list_empty(&cgrp->pidlists)); |
858 | |
859 | call_rcu(&cgrp->rcu_head, free_cgroup_rcu); |
860 | } |
861 | iput(inode); |
862 | } |
863 | |
864 | static int cgroup_delete(const struct dentry *d) |
865 | { |
866 | return 1; |
867 | } |
868 | |
869 | static void remove_dir(struct dentry *d) |
870 | { |
871 | struct dentry *parent = dget(d->d_parent); |
872 | |
873 | d_delete(d); |
874 | simple_rmdir(parent->d_inode, d); |
875 | dput(parent); |
876 | } |
877 | |
878 | static void cgroup_clear_directory(struct dentry *dentry) |
879 | { |
880 | struct list_head *node; |
881 | |
882 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); |
883 | spin_lock(&dentry->d_lock); |
884 | node = dentry->d_subdirs.next; |
885 | while (node != &dentry->d_subdirs) { |
886 | struct dentry *d = list_entry(node, struct dentry, d_u.d_child); |
887 | |
888 | spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); |
889 | list_del_init(node); |
890 | if (d->d_inode) { |
891 | /* This should never be called on a cgroup |
892 | * directory with child cgroups */ |
893 | BUG_ON(d->d_inode->i_mode & S_IFDIR); |
894 | dget_dlock(d); |
895 | spin_unlock(&d->d_lock); |
896 | spin_unlock(&dentry->d_lock); |
897 | d_delete(d); |
898 | simple_unlink(dentry->d_inode, d); |
899 | dput(d); |
900 | spin_lock(&dentry->d_lock); |
901 | } else |
902 | spin_unlock(&d->d_lock); |
903 | node = dentry->d_subdirs.next; |
904 | } |
905 | spin_unlock(&dentry->d_lock); |
906 | } |
907 | |
908 | /* |
909 | * NOTE : the dentry must have been dget()'ed |
910 | */ |
911 | static void cgroup_d_remove_dir(struct dentry *dentry) |
912 | { |
913 | struct dentry *parent; |
914 | |
915 | cgroup_clear_directory(dentry); |
916 | |
917 | parent = dentry->d_parent; |
918 | spin_lock(&parent->d_lock); |
919 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
920 | list_del_init(&dentry->d_u.d_child); |
921 | spin_unlock(&dentry->d_lock); |
922 | spin_unlock(&parent->d_lock); |
923 | remove_dir(dentry); |
924 | } |
925 | |
926 | /* |
927 | * A queue for waiters to do rmdir() cgroup. A tasks will sleep when |
928 | * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some |
929 | * reference to css->refcnt. In general, this refcnt is expected to goes down |
930 | * to zero, soon. |
931 | * |
932 | * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex; |
933 | */ |
934 | DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq); |
935 | |
936 | static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp) |
937 | { |
938 | if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))) |
939 | wake_up_all(&cgroup_rmdir_waitq); |
940 | } |
941 | |
942 | void cgroup_exclude_rmdir(struct cgroup_subsys_state *css) |
943 | { |
944 | css_get(css); |
945 | } |
946 | |
947 | void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css) |
948 | { |
949 | cgroup_wakeup_rmdir_waiter(css->cgroup); |
950 | css_put(css); |
951 | } |
952 | |
953 | /* |
954 | * Call with cgroup_mutex held. Drops reference counts on modules, including |
955 | * any duplicate ones that parse_cgroupfs_options took. If this function |
956 | * returns an error, no reference counts are touched. |
957 | */ |
958 | static int rebind_subsystems(struct cgroupfs_root *root, |
959 | unsigned long final_bits) |
960 | { |
961 | unsigned long added_bits, removed_bits; |
962 | struct cgroup *cgrp = &root->top_cgroup; |
963 | int i; |
964 | |
965 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
966 | |
967 | removed_bits = root->actual_subsys_bits & ~final_bits; |
968 | added_bits = final_bits & ~root->actual_subsys_bits; |
969 | /* Check that any added subsystems are currently free */ |
970 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
971 | unsigned long bit = 1UL << i; |
972 | struct cgroup_subsys *ss = subsys[i]; |
973 | if (!(bit & added_bits)) |
974 | continue; |
975 | /* |
976 | * Nobody should tell us to do a subsys that doesn't exist: |
977 | * parse_cgroupfs_options should catch that case and refcounts |
978 | * ensure that subsystems won't disappear once selected. |
979 | */ |
980 | BUG_ON(ss == NULL); |
981 | if (ss->root != &rootnode) { |
982 | /* Subsystem isn't free */ |
983 | return -EBUSY; |
984 | } |
985 | } |
986 | |
987 | /* Currently we don't handle adding/removing subsystems when |
988 | * any child cgroups exist. This is theoretically supportable |
989 | * but involves complex error handling, so it's being left until |
990 | * later */ |
991 | if (root->number_of_cgroups > 1) |
992 | return -EBUSY; |
993 | |
994 | /* Process each subsystem */ |
995 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
996 | struct cgroup_subsys *ss = subsys[i]; |
997 | unsigned long bit = 1UL << i; |
998 | if (bit & added_bits) { |
999 | /* We're binding this subsystem to this hierarchy */ |
1000 | BUG_ON(ss == NULL); |
1001 | BUG_ON(cgrp->subsys[i]); |
1002 | BUG_ON(!dummytop->subsys[i]); |
1003 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); |
1004 | mutex_lock(&ss->hierarchy_mutex); |
1005 | cgrp->subsys[i] = dummytop->subsys[i]; |
1006 | cgrp->subsys[i]->cgroup = cgrp; |
1007 | list_move(&ss->sibling, &root->subsys_list); |
1008 | ss->root = root; |
1009 | if (ss->bind) |
1010 | ss->bind(ss, cgrp); |
1011 | mutex_unlock(&ss->hierarchy_mutex); |
1012 | /* refcount was already taken, and we're keeping it */ |
1013 | } else if (bit & removed_bits) { |
1014 | /* We're removing this subsystem */ |
1015 | BUG_ON(ss == NULL); |
1016 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
1017 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); |
1018 | mutex_lock(&ss->hierarchy_mutex); |
1019 | if (ss->bind) |
1020 | ss->bind(ss, dummytop); |
1021 | dummytop->subsys[i]->cgroup = dummytop; |
1022 | cgrp->subsys[i] = NULL; |
1023 | subsys[i]->root = &rootnode; |
1024 | list_move(&ss->sibling, &rootnode.subsys_list); |
1025 | mutex_unlock(&ss->hierarchy_mutex); |
1026 | /* subsystem is now free - drop reference on module */ |
1027 | module_put(ss->module); |
1028 | } else if (bit & final_bits) { |
1029 | /* Subsystem state should already exist */ |
1030 | BUG_ON(ss == NULL); |
1031 | BUG_ON(!cgrp->subsys[i]); |
1032 | /* |
1033 | * a refcount was taken, but we already had one, so |
1034 | * drop the extra reference. |
1035 | */ |
1036 | module_put(ss->module); |
1037 | #ifdef CONFIG_MODULE_UNLOAD |
1038 | BUG_ON(ss->module && !module_refcount(ss->module)); |
1039 | #endif |
1040 | } else { |
1041 | /* Subsystem state shouldn't exist */ |
1042 | BUG_ON(cgrp->subsys[i]); |
1043 | } |
1044 | } |
1045 | root->subsys_bits = root->actual_subsys_bits = final_bits; |
1046 | synchronize_rcu(); |
1047 | |
1048 | return 0; |
1049 | } |
1050 | |
1051 | static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) |
1052 | { |
1053 | struct cgroupfs_root *root = vfs->mnt_sb->s_fs_info; |
1054 | struct cgroup_subsys *ss; |
1055 | |
1056 | mutex_lock(&cgroup_mutex); |
1057 | for_each_subsys(root, ss) |
1058 | seq_printf(seq, ",%s", ss->name); |
1059 | if (test_bit(ROOT_NOPREFIX, &root->flags)) |
1060 | seq_puts(seq, ",noprefix"); |
1061 | if (strlen(root->release_agent_path)) |
1062 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); |
1063 | if (clone_children(&root->top_cgroup)) |
1064 | seq_puts(seq, ",clone_children"); |
1065 | if (strlen(root->name)) |
1066 | seq_printf(seq, ",name=%s", root->name); |
1067 | mutex_unlock(&cgroup_mutex); |
1068 | return 0; |
1069 | } |
1070 | |
1071 | struct cgroup_sb_opts { |
1072 | unsigned long subsys_bits; |
1073 | unsigned long flags; |
1074 | char *release_agent; |
1075 | bool clone_children; |
1076 | char *name; |
1077 | /* User explicitly requested empty subsystem */ |
1078 | bool none; |
1079 | |
1080 | struct cgroupfs_root *new_root; |
1081 | |
1082 | }; |
1083 | |
1084 | /* |
1085 | * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call |
1086 | * with cgroup_mutex held to protect the subsys[] array. This function takes |
1087 | * refcounts on subsystems to be used, unless it returns error, in which case |
1088 | * no refcounts are taken. |
1089 | */ |
1090 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
1091 | { |
1092 | char *token, *o = data; |
1093 | bool all_ss = false, one_ss = false; |
1094 | unsigned long mask = (unsigned long)-1; |
1095 | int i; |
1096 | bool module_pin_failed = false; |
1097 | |
1098 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1099 | |
1100 | #ifdef CONFIG_CPUSETS |
1101 | mask = ~(1UL << cpuset_subsys_id); |
1102 | #endif |
1103 | |
1104 | memset(opts, 0, sizeof(*opts)); |
1105 | |
1106 | while ((token = strsep(&o, ",")) != NULL) { |
1107 | if (!*token) |
1108 | return -EINVAL; |
1109 | if (!strcmp(token, "none")) { |
1110 | /* Explicitly have no subsystems */ |
1111 | opts->none = true; |
1112 | continue; |
1113 | } |
1114 | if (!strcmp(token, "all")) { |
1115 | /* Mutually exclusive option 'all' + subsystem name */ |
1116 | if (one_ss) |
1117 | return -EINVAL; |
1118 | all_ss = true; |
1119 | continue; |
1120 | } |
1121 | if (!strcmp(token, "noprefix")) { |
1122 | set_bit(ROOT_NOPREFIX, &opts->flags); |
1123 | continue; |
1124 | } |
1125 | if (!strcmp(token, "clone_children")) { |
1126 | opts->clone_children = true; |
1127 | continue; |
1128 | } |
1129 | if (!strncmp(token, "release_agent=", 14)) { |
1130 | /* Specifying two release agents is forbidden */ |
1131 | if (opts->release_agent) |
1132 | return -EINVAL; |
1133 | opts->release_agent = |
1134 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
1135 | if (!opts->release_agent) |
1136 | return -ENOMEM; |
1137 | continue; |
1138 | } |
1139 | if (!strncmp(token, "name=", 5)) { |
1140 | const char *name = token + 5; |
1141 | /* Can't specify an empty name */ |
1142 | if (!strlen(name)) |
1143 | return -EINVAL; |
1144 | /* Must match [\w.-]+ */ |
1145 | for (i = 0; i < strlen(name); i++) { |
1146 | char c = name[i]; |
1147 | if (isalnum(c)) |
1148 | continue; |
1149 | if ((c == '.') || (c == '-') || (c == '_')) |
1150 | continue; |
1151 | return -EINVAL; |
1152 | } |
1153 | /* Specifying two names is forbidden */ |
1154 | if (opts->name) |
1155 | return -EINVAL; |
1156 | opts->name = kstrndup(name, |
1157 | MAX_CGROUP_ROOT_NAMELEN - 1, |
1158 | GFP_KERNEL); |
1159 | if (!opts->name) |
1160 | return -ENOMEM; |
1161 | |
1162 | continue; |
1163 | } |
1164 | |
1165 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
1166 | struct cgroup_subsys *ss = subsys[i]; |
1167 | if (ss == NULL) |
1168 | continue; |
1169 | if (strcmp(token, ss->name)) |
1170 | continue; |
1171 | if (ss->disabled) |
1172 | continue; |
1173 | |
1174 | /* Mutually exclusive option 'all' + subsystem name */ |
1175 | if (all_ss) |
1176 | return -EINVAL; |
1177 | set_bit(i, &opts->subsys_bits); |
1178 | one_ss = true; |
1179 | |
1180 | break; |
1181 | } |
1182 | if (i == CGROUP_SUBSYS_COUNT) |
1183 | return -ENOENT; |
1184 | } |
1185 | |
1186 | /* |
1187 | * If the 'all' option was specified select all the subsystems, |
1188 | * otherwise 'all, 'none' and a subsystem name options were not |
1189 | * specified, let's default to 'all' |
1190 | */ |
1191 | if (all_ss || (!all_ss && !one_ss && !opts->none)) { |
1192 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
1193 | struct cgroup_subsys *ss = subsys[i]; |
1194 | if (ss == NULL) |
1195 | continue; |
1196 | if (ss->disabled) |
1197 | continue; |
1198 | set_bit(i, &opts->subsys_bits); |
1199 | } |
1200 | } |
1201 | |
1202 | /* Consistency checks */ |
1203 | |
1204 | /* |
1205 | * Option noprefix was introduced just for backward compatibility |
1206 | * with the old cpuset, so we allow noprefix only if mounting just |
1207 | * the cpuset subsystem. |
1208 | */ |
1209 | if (test_bit(ROOT_NOPREFIX, &opts->flags) && |
1210 | (opts->subsys_bits & mask)) |
1211 | return -EINVAL; |
1212 | |
1213 | |
1214 | /* Can't specify "none" and some subsystems */ |
1215 | if (opts->subsys_bits && opts->none) |
1216 | return -EINVAL; |
1217 | |
1218 | /* |
1219 | * We either have to specify by name or by subsystems. (So all |
1220 | * empty hierarchies must have a name). |
1221 | */ |
1222 | if (!opts->subsys_bits && !opts->name) |
1223 | return -EINVAL; |
1224 | |
1225 | /* |
1226 | * Grab references on all the modules we'll need, so the subsystems |
1227 | * don't dance around before rebind_subsystems attaches them. This may |
1228 | * take duplicate reference counts on a subsystem that's already used, |
1229 | * but rebind_subsystems handles this case. |
1230 | */ |
1231 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { |
1232 | unsigned long bit = 1UL << i; |
1233 | |
1234 | if (!(bit & opts->subsys_bits)) |
1235 | continue; |
1236 | if (!try_module_get(subsys[i]->module)) { |
1237 | module_pin_failed = true; |
1238 | break; |
1239 | } |
1240 | } |
1241 | if (module_pin_failed) { |
1242 | /* |
1243 | * oops, one of the modules was going away. this means that we |
1244 | * raced with a module_delete call, and to the user this is |
1245 | * essentially a "subsystem doesn't exist" case. |
1246 | */ |
1247 | for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) { |
1248 | /* drop refcounts only on the ones we took */ |
1249 | unsigned long bit = 1UL << i; |
1250 | |
1251 | if (!(bit & opts->subsys_bits)) |
1252 | continue; |
1253 | module_put(subsys[i]->module); |
1254 | } |
1255 | return -ENOENT; |
1256 | } |
1257 | |
1258 | return 0; |
1259 | } |
1260 | |
1261 | static void drop_parsed_module_refcounts(unsigned long subsys_bits) |
1262 | { |
1263 | int i; |
1264 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { |
1265 | unsigned long bit = 1UL << i; |
1266 | |
1267 | if (!(bit & subsys_bits)) |
1268 | continue; |
1269 | module_put(subsys[i]->module); |
1270 | } |
1271 | } |
1272 | |
1273 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) |
1274 | { |
1275 | int ret = 0; |
1276 | struct cgroupfs_root *root = sb->s_fs_info; |
1277 | struct cgroup *cgrp = &root->top_cgroup; |
1278 | struct cgroup_sb_opts opts; |
1279 | |
1280 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
1281 | mutex_lock(&cgroup_mutex); |
1282 | |
1283 | /* See what subsystems are wanted */ |
1284 | ret = parse_cgroupfs_options(data, &opts); |
1285 | if (ret) |
1286 | goto out_unlock; |
1287 | |
1288 | /* Don't allow flags or name to change at remount */ |
1289 | if (opts.flags != root->flags || |
1290 | (opts.name && strcmp(opts.name, root->name))) { |
1291 | ret = -EINVAL; |
1292 | drop_parsed_module_refcounts(opts.subsys_bits); |
1293 | goto out_unlock; |
1294 | } |
1295 | |
1296 | ret = rebind_subsystems(root, opts.subsys_bits); |
1297 | if (ret) { |
1298 | drop_parsed_module_refcounts(opts.subsys_bits); |
1299 | goto out_unlock; |
1300 | } |
1301 | |
1302 | /* (re)populate subsystem files */ |
1303 | cgroup_populate_dir(cgrp); |
1304 | |
1305 | if (opts.release_agent) |
1306 | strcpy(root->release_agent_path, opts.release_agent); |
1307 | out_unlock: |
1308 | kfree(opts.release_agent); |
1309 | kfree(opts.name); |
1310 | mutex_unlock(&cgroup_mutex); |
1311 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
1312 | return ret; |
1313 | } |
1314 | |
1315 | static const struct super_operations cgroup_ops = { |
1316 | .statfs = simple_statfs, |
1317 | .drop_inode = generic_delete_inode, |
1318 | .show_options = cgroup_show_options, |
1319 | .remount_fs = cgroup_remount, |
1320 | }; |
1321 | |
1322 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1323 | { |
1324 | INIT_LIST_HEAD(&cgrp->sibling); |
1325 | INIT_LIST_HEAD(&cgrp->children); |
1326 | INIT_LIST_HEAD(&cgrp->css_sets); |
1327 | INIT_LIST_HEAD(&cgrp->release_list); |
1328 | INIT_LIST_HEAD(&cgrp->pidlists); |
1329 | mutex_init(&cgrp->pidlist_mutex); |
1330 | INIT_LIST_HEAD(&cgrp->event_list); |
1331 | spin_lock_init(&cgrp->event_list_lock); |
1332 | } |
1333 | |
1334 | static void init_cgroup_root(struct cgroupfs_root *root) |
1335 | { |
1336 | struct cgroup *cgrp = &root->top_cgroup; |
1337 | INIT_LIST_HEAD(&root->subsys_list); |
1338 | INIT_LIST_HEAD(&root->root_list); |
1339 | root->number_of_cgroups = 1; |
1340 | cgrp->root = root; |
1341 | cgrp->top_cgroup = cgrp; |
1342 | init_cgroup_housekeeping(cgrp); |
1343 | } |
1344 | |
1345 | static bool init_root_id(struct cgroupfs_root *root) |
1346 | { |
1347 | int ret = 0; |
1348 | |
1349 | do { |
1350 | if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) |
1351 | return false; |
1352 | spin_lock(&hierarchy_id_lock); |
1353 | /* Try to allocate the next unused ID */ |
1354 | ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, |
1355 | &root->hierarchy_id); |
1356 | if (ret == -ENOSPC) |
1357 | /* Try again starting from 0 */ |
1358 | ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id); |
1359 | if (!ret) { |
1360 | next_hierarchy_id = root->hierarchy_id + 1; |
1361 | } else if (ret != -EAGAIN) { |
1362 | /* Can only get here if the 31-bit IDR is full ... */ |
1363 | BUG_ON(ret); |
1364 | } |
1365 | spin_unlock(&hierarchy_id_lock); |
1366 | } while (ret); |
1367 | return true; |
1368 | } |
1369 | |
1370 | static int cgroup_test_super(struct super_block *sb, void *data) |
1371 | { |
1372 | struct cgroup_sb_opts *opts = data; |
1373 | struct cgroupfs_root *root = sb->s_fs_info; |
1374 | |
1375 | /* If we asked for a name then it must match */ |
1376 | if (opts->name && strcmp(opts->name, root->name)) |
1377 | return 0; |
1378 | |
1379 | /* |
1380 | * If we asked for subsystems (or explicitly for no |
1381 | * subsystems) then they must match |
1382 | */ |
1383 | if ((opts->subsys_bits || opts->none) |
1384 | && (opts->subsys_bits != root->subsys_bits)) |
1385 | return 0; |
1386 | |
1387 | return 1; |
1388 | } |
1389 | |
1390 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1391 | { |
1392 | struct cgroupfs_root *root; |
1393 | |
1394 | if (!opts->subsys_bits && !opts->none) |
1395 | return NULL; |
1396 | |
1397 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
1398 | if (!root) |
1399 | return ERR_PTR(-ENOMEM); |
1400 | |
1401 | if (!init_root_id(root)) { |
1402 | kfree(root); |
1403 | return ERR_PTR(-ENOMEM); |
1404 | } |
1405 | init_cgroup_root(root); |
1406 | |
1407 | root->subsys_bits = opts->subsys_bits; |
1408 | root->flags = opts->flags; |
1409 | if (opts->release_agent) |
1410 | strcpy(root->release_agent_path, opts->release_agent); |
1411 | if (opts->name) |
1412 | strcpy(root->name, opts->name); |
1413 | if (opts->clone_children) |
1414 | set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags); |
1415 | return root; |
1416 | } |
1417 | |
1418 | static void cgroup_drop_root(struct cgroupfs_root *root) |
1419 | { |
1420 | if (!root) |
1421 | return; |
1422 | |
1423 | BUG_ON(!root->hierarchy_id); |
1424 | spin_lock(&hierarchy_id_lock); |
1425 | ida_remove(&hierarchy_ida, root->hierarchy_id); |
1426 | spin_unlock(&hierarchy_id_lock); |
1427 | kfree(root); |
1428 | } |
1429 | |
1430 | static int cgroup_set_super(struct super_block *sb, void *data) |
1431 | { |
1432 | int ret; |
1433 | struct cgroup_sb_opts *opts = data; |
1434 | |
1435 | /* If we don't have a new root, we can't set up a new sb */ |
1436 | if (!opts->new_root) |
1437 | return -EINVAL; |
1438 | |
1439 | BUG_ON(!opts->subsys_bits && !opts->none); |
1440 | |
1441 | ret = set_anon_super(sb, NULL); |
1442 | if (ret) |
1443 | return ret; |
1444 | |
1445 | sb->s_fs_info = opts->new_root; |
1446 | opts->new_root->sb = sb; |
1447 | |
1448 | sb->s_blocksize = PAGE_CACHE_SIZE; |
1449 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
1450 | sb->s_magic = CGROUP_SUPER_MAGIC; |
1451 | sb->s_op = &cgroup_ops; |
1452 | |
1453 | return 0; |
1454 | } |
1455 | |
1456 | static int cgroup_get_rootdir(struct super_block *sb) |
1457 | { |
1458 | static const struct dentry_operations cgroup_dops = { |
1459 | .d_iput = cgroup_diput, |
1460 | .d_delete = cgroup_delete, |
1461 | }; |
1462 | |
1463 | struct inode *inode = |
1464 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); |
1465 | struct dentry *dentry; |
1466 | |
1467 | if (!inode) |
1468 | return -ENOMEM; |
1469 | |
1470 | inode->i_fop = &simple_dir_operations; |
1471 | inode->i_op = &cgroup_dir_inode_operations; |
1472 | /* directories start off with i_nlink == 2 (for "." entry) */ |
1473 | inc_nlink(inode); |
1474 | dentry = d_alloc_root(inode); |
1475 | if (!dentry) { |
1476 | iput(inode); |
1477 | return -ENOMEM; |
1478 | } |
1479 | sb->s_root = dentry; |
1480 | /* for everything else we want ->d_op set */ |
1481 | sb->s_d_op = &cgroup_dops; |
1482 | return 0; |
1483 | } |
1484 | |
1485 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
1486 | int flags, const char *unused_dev_name, |
1487 | void *data) |
1488 | { |
1489 | struct cgroup_sb_opts opts; |
1490 | struct cgroupfs_root *root; |
1491 | int ret = 0; |
1492 | struct super_block *sb; |
1493 | struct cgroupfs_root *new_root; |
1494 | |
1495 | /* First find the desired set of subsystems */ |
1496 | mutex_lock(&cgroup_mutex); |
1497 | ret = parse_cgroupfs_options(data, &opts); |
1498 | mutex_unlock(&cgroup_mutex); |
1499 | if (ret) |
1500 | goto out_err; |
1501 | |
1502 | /* |
1503 | * Allocate a new cgroup root. We may not need it if we're |
1504 | * reusing an existing hierarchy. |
1505 | */ |
1506 | new_root = cgroup_root_from_opts(&opts); |
1507 | if (IS_ERR(new_root)) { |
1508 | ret = PTR_ERR(new_root); |
1509 | goto drop_modules; |
1510 | } |
1511 | opts.new_root = new_root; |
1512 | |
1513 | /* Locate an existing or new sb for this hierarchy */ |
1514 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts); |
1515 | if (IS_ERR(sb)) { |
1516 | ret = PTR_ERR(sb); |
1517 | cgroup_drop_root(opts.new_root); |
1518 | goto drop_modules; |
1519 | } |
1520 | |
1521 | root = sb->s_fs_info; |
1522 | BUG_ON(!root); |
1523 | if (root == opts.new_root) { |
1524 | /* We used the new root structure, so this is a new hierarchy */ |
1525 | struct list_head tmp_cg_links; |
1526 | struct cgroup *root_cgrp = &root->top_cgroup; |
1527 | struct inode *inode; |
1528 | struct cgroupfs_root *existing_root; |
1529 | int i; |
1530 | |
1531 | BUG_ON(sb->s_root != NULL); |
1532 | |
1533 | ret = cgroup_get_rootdir(sb); |
1534 | if (ret) |
1535 | goto drop_new_super; |
1536 | inode = sb->s_root->d_inode; |
1537 | |
1538 | mutex_lock(&inode->i_mutex); |
1539 | mutex_lock(&cgroup_mutex); |
1540 | |
1541 | if (strlen(root->name)) { |
1542 | /* Check for name clashes with existing mounts */ |
1543 | for_each_active_root(existing_root) { |
1544 | if (!strcmp(existing_root->name, root->name)) { |
1545 | ret = -EBUSY; |
1546 | mutex_unlock(&cgroup_mutex); |
1547 | mutex_unlock(&inode->i_mutex); |
1548 | goto drop_new_super; |
1549 | } |
1550 | } |
1551 | } |
1552 | |
1553 | /* |
1554 | * We're accessing css_set_count without locking |
1555 | * css_set_lock here, but that's OK - it can only be |
1556 | * increased by someone holding cgroup_lock, and |
1557 | * that's us. The worst that can happen is that we |
1558 | * have some link structures left over |
1559 | */ |
1560 | ret = allocate_cg_links(css_set_count, &tmp_cg_links); |
1561 | if (ret) { |
1562 | mutex_unlock(&cgroup_mutex); |
1563 | mutex_unlock(&inode->i_mutex); |
1564 | goto drop_new_super; |
1565 | } |
1566 | |
1567 | ret = rebind_subsystems(root, root->subsys_bits); |
1568 | if (ret == -EBUSY) { |
1569 | mutex_unlock(&cgroup_mutex); |
1570 | mutex_unlock(&inode->i_mutex); |
1571 | free_cg_links(&tmp_cg_links); |
1572 | goto drop_new_super; |
1573 | } |
1574 | /* |
1575 | * There must be no failure case after here, since rebinding |
1576 | * takes care of subsystems' refcounts, which are explicitly |
1577 | * dropped in the failure exit path. |
1578 | */ |
1579 | |
1580 | /* EBUSY should be the only error here */ |
1581 | BUG_ON(ret); |
1582 | |
1583 | list_add(&root->root_list, &roots); |
1584 | root_count++; |
1585 | |
1586 | sb->s_root->d_fsdata = root_cgrp; |
1587 | root->top_cgroup.dentry = sb->s_root; |
1588 | |
1589 | /* Link the top cgroup in this hierarchy into all |
1590 | * the css_set objects */ |
1591 | write_lock(&css_set_lock); |
1592 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { |
1593 | struct hlist_head *hhead = &css_set_table[i]; |
1594 | struct hlist_node *node; |
1595 | struct css_set *cg; |
1596 | |
1597 | hlist_for_each_entry(cg, node, hhead, hlist) |
1598 | link_css_set(&tmp_cg_links, cg, root_cgrp); |
1599 | } |
1600 | write_unlock(&css_set_lock); |
1601 | |
1602 | free_cg_links(&tmp_cg_links); |
1603 | |
1604 | BUG_ON(!list_empty(&root_cgrp->sibling)); |
1605 | BUG_ON(!list_empty(&root_cgrp->children)); |
1606 | BUG_ON(root->number_of_cgroups != 1); |
1607 | |
1608 | cgroup_populate_dir(root_cgrp); |
1609 | mutex_unlock(&cgroup_mutex); |
1610 | mutex_unlock(&inode->i_mutex); |
1611 | } else { |
1612 | /* |
1613 | * We re-used an existing hierarchy - the new root (if |
1614 | * any) is not needed |
1615 | */ |
1616 | cgroup_drop_root(opts.new_root); |
1617 | /* no subsys rebinding, so refcounts don't change */ |
1618 | drop_parsed_module_refcounts(opts.subsys_bits); |
1619 | } |
1620 | |
1621 | kfree(opts.release_agent); |
1622 | kfree(opts.name); |
1623 | return dget(sb->s_root); |
1624 | |
1625 | drop_new_super: |
1626 | deactivate_locked_super(sb); |
1627 | drop_modules: |
1628 | drop_parsed_module_refcounts(opts.subsys_bits); |
1629 | out_err: |
1630 | kfree(opts.release_agent); |
1631 | kfree(opts.name); |
1632 | return ERR_PTR(ret); |
1633 | } |
1634 | |
1635 | static void cgroup_kill_sb(struct super_block *sb) { |
1636 | struct cgroupfs_root *root = sb->s_fs_info; |
1637 | struct cgroup *cgrp = &root->top_cgroup; |
1638 | int ret; |
1639 | struct cg_cgroup_link *link; |
1640 | struct cg_cgroup_link *saved_link; |
1641 | |
1642 | BUG_ON(!root); |
1643 | |
1644 | BUG_ON(root->number_of_cgroups != 1); |
1645 | BUG_ON(!list_empty(&cgrp->children)); |
1646 | BUG_ON(!list_empty(&cgrp->sibling)); |
1647 | |
1648 | mutex_lock(&cgroup_mutex); |
1649 | |
1650 | /* Rebind all subsystems back to the default hierarchy */ |
1651 | ret = rebind_subsystems(root, 0); |
1652 | /* Shouldn't be able to fail ... */ |
1653 | BUG_ON(ret); |
1654 | |
1655 | /* |
1656 | * Release all the links from css_sets to this hierarchy's |
1657 | * root cgroup |
1658 | */ |
1659 | write_lock(&css_set_lock); |
1660 | |
1661 | list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, |
1662 | cgrp_link_list) { |
1663 | list_del(&link->cg_link_list); |
1664 | list_del(&link->cgrp_link_list); |
1665 | kfree(link); |
1666 | } |
1667 | write_unlock(&css_set_lock); |
1668 | |
1669 | if (!list_empty(&root->root_list)) { |
1670 | list_del(&root->root_list); |
1671 | root_count--; |
1672 | } |
1673 | |
1674 | mutex_unlock(&cgroup_mutex); |
1675 | |
1676 | kill_litter_super(sb); |
1677 | cgroup_drop_root(root); |
1678 | } |
1679 | |
1680 | static struct file_system_type cgroup_fs_type = { |
1681 | .name = "cgroup", |
1682 | .mount = cgroup_mount, |
1683 | .kill_sb = cgroup_kill_sb, |
1684 | }; |
1685 | |
1686 | static struct kobject *cgroup_kobj; |
1687 | |
1688 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
1689 | { |
1690 | return dentry->d_fsdata; |
1691 | } |
1692 | |
1693 | static inline struct cftype *__d_cft(struct dentry *dentry) |
1694 | { |
1695 | return dentry->d_fsdata; |
1696 | } |
1697 | |
1698 | /** |
1699 | * cgroup_path - generate the path of a cgroup |
1700 | * @cgrp: the cgroup in question |
1701 | * @buf: the buffer to write the path into |
1702 | * @buflen: the length of the buffer |
1703 | * |
1704 | * Called with cgroup_mutex held or else with an RCU-protected cgroup |
1705 | * reference. Writes path of cgroup into buf. Returns 0 on success, |
1706 | * -errno on error. |
1707 | */ |
1708 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
1709 | { |
1710 | char *start; |
1711 | struct dentry *dentry = rcu_dereference_check(cgrp->dentry, |
1712 | rcu_read_lock_held() || |
1713 | cgroup_lock_is_held()); |
1714 | |
1715 | if (!dentry || cgrp == dummytop) { |
1716 | /* |
1717 | * Inactive subsystems have no dentry for their root |
1718 | * cgroup |
1719 | */ |
1720 | strcpy(buf, "/"); |
1721 | return 0; |
1722 | } |
1723 | |
1724 | start = buf + buflen; |
1725 | |
1726 | *--start = '\0'; |
1727 | for (;;) { |
1728 | int len = dentry->d_name.len; |
1729 | |
1730 | if ((start -= len) < buf) |
1731 | return -ENAMETOOLONG; |
1732 | memcpy(start, dentry->d_name.name, len); |
1733 | cgrp = cgrp->parent; |
1734 | if (!cgrp) |
1735 | break; |
1736 | |
1737 | dentry = rcu_dereference_check(cgrp->dentry, |
1738 | rcu_read_lock_held() || |
1739 | cgroup_lock_is_held()); |
1740 | if (!cgrp->parent) |
1741 | continue; |
1742 | if (--start < buf) |
1743 | return -ENAMETOOLONG; |
1744 | *start = '/'; |
1745 | } |
1746 | memmove(buf, start, buf + buflen - start); |
1747 | return 0; |
1748 | } |
1749 | EXPORT_SYMBOL_GPL(cgroup_path); |
1750 | |
1751 | /** |
1752 | * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' |
1753 | * @cgrp: the cgroup the task is attaching to |
1754 | * @tsk: the task to be attached |
1755 | * |
1756 | * Call holding cgroup_mutex. May take task_lock of |
1757 | * the task 'tsk' during call. |
1758 | */ |
1759 | int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
1760 | { |
1761 | int retval = 0; |
1762 | struct cgroup_subsys *ss, *failed_ss = NULL; |
1763 | struct cgroup *oldcgrp; |
1764 | struct css_set *cg; |
1765 | struct css_set *newcg; |
1766 | struct cgroupfs_root *root = cgrp->root; |
1767 | |
1768 | /* Nothing to do if the task is already in that cgroup */ |
1769 | oldcgrp = task_cgroup_from_root(tsk, root); |
1770 | if (cgrp == oldcgrp) |
1771 | return 0; |
1772 | |
1773 | for_each_subsys(root, ss) { |
1774 | if (ss->can_attach) { |
1775 | retval = ss->can_attach(ss, cgrp, tsk, false); |
1776 | if (retval) { |
1777 | /* |
1778 | * Remember on which subsystem the can_attach() |
1779 | * failed, so that we only call cancel_attach() |
1780 | * against the subsystems whose can_attach() |
1781 | * succeeded. (See below) |
1782 | */ |
1783 | failed_ss = ss; |
1784 | goto out; |
1785 | } |
1786 | } |
1787 | } |
1788 | |
1789 | task_lock(tsk); |
1790 | cg = tsk->cgroups; |
1791 | get_css_set(cg); |
1792 | task_unlock(tsk); |
1793 | /* |
1794 | * Locate or allocate a new css_set for this task, |
1795 | * based on its final set of cgroups |
1796 | */ |
1797 | newcg = find_css_set(cg, cgrp); |
1798 | put_css_set(cg); |
1799 | if (!newcg) { |
1800 | retval = -ENOMEM; |
1801 | goto out; |
1802 | } |
1803 | |
1804 | task_lock(tsk); |
1805 | if (tsk->flags & PF_EXITING) { |
1806 | task_unlock(tsk); |
1807 | put_css_set(newcg); |
1808 | retval = -ESRCH; |
1809 | goto out; |
1810 | } |
1811 | rcu_assign_pointer(tsk->cgroups, newcg); |
1812 | task_unlock(tsk); |
1813 | |
1814 | /* Update the css_set linked lists if we're using them */ |
1815 | write_lock(&css_set_lock); |
1816 | if (!list_empty(&tsk->cg_list)) |
1817 | list_move(&tsk->cg_list, &newcg->tasks); |
1818 | write_unlock(&css_set_lock); |
1819 | |
1820 | for_each_subsys(root, ss) { |
1821 | if (ss->attach) |
1822 | ss->attach(ss, cgrp, oldcgrp, tsk, false); |
1823 | } |
1824 | set_bit(CGRP_RELEASABLE, &oldcgrp->flags); |
1825 | synchronize_rcu(); |
1826 | put_css_set(cg); |
1827 | |
1828 | /* |
1829 | * wake up rmdir() waiter. the rmdir should fail since the cgroup |
1830 | * is no longer empty. |
1831 | */ |
1832 | cgroup_wakeup_rmdir_waiter(cgrp); |
1833 | out: |
1834 | if (retval) { |
1835 | for_each_subsys(root, ss) { |
1836 | if (ss == failed_ss) |
1837 | /* |
1838 | * This subsystem was the one that failed the |
1839 | * can_attach() check earlier, so we don't need |
1840 | * to call cancel_attach() against it or any |
1841 | * remaining subsystems. |
1842 | */ |
1843 | break; |
1844 | if (ss->cancel_attach) |
1845 | ss->cancel_attach(ss, cgrp, tsk, false); |
1846 | } |
1847 | } |
1848 | return retval; |
1849 | } |
1850 | |
1851 | /** |
1852 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' |
1853 | * @from: attach to all cgroups of a given task |
1854 | * @tsk: the task to be attached |
1855 | */ |
1856 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) |
1857 | { |
1858 | struct cgroupfs_root *root; |
1859 | int retval = 0; |
1860 | |
1861 | cgroup_lock(); |
1862 | for_each_active_root(root) { |
1863 | struct cgroup *from_cg = task_cgroup_from_root(from, root); |
1864 | |
1865 | retval = cgroup_attach_task(from_cg, tsk); |
1866 | if (retval) |
1867 | break; |
1868 | } |
1869 | cgroup_unlock(); |
1870 | |
1871 | return retval; |
1872 | } |
1873 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
1874 | |
1875 | /* |
1876 | * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex |
1877 | * held. May take task_lock of task |
1878 | */ |
1879 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid) |
1880 | { |
1881 | struct task_struct *tsk; |
1882 | const struct cred *cred = current_cred(), *tcred; |
1883 | int ret; |
1884 | |
1885 | if (pid) { |
1886 | rcu_read_lock(); |
1887 | tsk = find_task_by_vpid(pid); |
1888 | if (!tsk || tsk->flags & PF_EXITING) { |
1889 | rcu_read_unlock(); |
1890 | return -ESRCH; |
1891 | } |
1892 | |
1893 | tcred = __task_cred(tsk); |
1894 | if (cred->euid && |
1895 | cred->euid != tcred->uid && |
1896 | cred->euid != tcred->suid) { |
1897 | rcu_read_unlock(); |
1898 | return -EACCES; |
1899 | } |
1900 | get_task_struct(tsk); |
1901 | rcu_read_unlock(); |
1902 | } else { |
1903 | tsk = current; |
1904 | get_task_struct(tsk); |
1905 | } |
1906 | |
1907 | ret = cgroup_attach_task(cgrp, tsk); |
1908 | put_task_struct(tsk); |
1909 | return ret; |
1910 | } |
1911 | |
1912 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
1913 | { |
1914 | int ret; |
1915 | if (!cgroup_lock_live_group(cgrp)) |
1916 | return -ENODEV; |
1917 | ret = attach_task_by_pid(cgrp, pid); |
1918 | cgroup_unlock(); |
1919 | return ret; |
1920 | } |
1921 | |
1922 | /** |
1923 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. |
1924 | * @cgrp: the cgroup to be checked for liveness |
1925 | * |
1926 | * On success, returns true; the lock should be later released with |
1927 | * cgroup_unlock(). On failure returns false with no lock held. |
1928 | */ |
1929 | bool cgroup_lock_live_group(struct cgroup *cgrp) |
1930 | { |
1931 | mutex_lock(&cgroup_mutex); |
1932 | if (cgroup_is_removed(cgrp)) { |
1933 | mutex_unlock(&cgroup_mutex); |
1934 | return false; |
1935 | } |
1936 | return true; |
1937 | } |
1938 | EXPORT_SYMBOL_GPL(cgroup_lock_live_group); |
1939 | |
1940 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, |
1941 | const char *buffer) |
1942 | { |
1943 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
1944 | if (strlen(buffer) >= PATH_MAX) |
1945 | return -EINVAL; |
1946 | if (!cgroup_lock_live_group(cgrp)) |
1947 | return -ENODEV; |
1948 | strcpy(cgrp->root->release_agent_path, buffer); |
1949 | cgroup_unlock(); |
1950 | return 0; |
1951 | } |
1952 | |
1953 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, |
1954 | struct seq_file *seq) |
1955 | { |
1956 | if (!cgroup_lock_live_group(cgrp)) |
1957 | return -ENODEV; |
1958 | seq_puts(seq, cgrp->root->release_agent_path); |
1959 | seq_putc(seq, '\n'); |
1960 | cgroup_unlock(); |
1961 | return 0; |
1962 | } |
1963 | |
1964 | /* A buffer size big enough for numbers or short strings */ |
1965 | #define CGROUP_LOCAL_BUFFER_SIZE 64 |
1966 | |
1967 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
1968 | struct file *file, |
1969 | const char __user *userbuf, |
1970 | size_t nbytes, loff_t *unused_ppos) |
1971 | { |
1972 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
1973 | int retval = 0; |
1974 | char *end; |
1975 | |
1976 | if (!nbytes) |
1977 | return -EINVAL; |
1978 | if (nbytes >= sizeof(buffer)) |
1979 | return -E2BIG; |
1980 | if (copy_from_user(buffer, userbuf, nbytes)) |
1981 | return -EFAULT; |
1982 | |
1983 | buffer[nbytes] = 0; /* nul-terminate */ |
1984 | if (cft->write_u64) { |
1985 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
1986 | if (*end) |
1987 | return -EINVAL; |
1988 | retval = cft->write_u64(cgrp, cft, val); |
1989 | } else { |
1990 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
1991 | if (*end) |
1992 | return -EINVAL; |
1993 | retval = cft->write_s64(cgrp, cft, val); |
1994 | } |
1995 | if (!retval) |
1996 | retval = nbytes; |
1997 | return retval; |
1998 | } |
1999 | |
2000 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
2001 | struct file *file, |
2002 | const char __user *userbuf, |
2003 | size_t nbytes, loff_t *unused_ppos) |
2004 | { |
2005 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
2006 | int retval = 0; |
2007 | size_t max_bytes = cft->max_write_len; |
2008 | char *buffer = local_buffer; |
2009 | |
2010 | if (!max_bytes) |
2011 | max_bytes = sizeof(local_buffer) - 1; |
2012 | if (nbytes >= max_bytes) |
2013 | return -E2BIG; |
2014 | /* Allocate a dynamic buffer if we need one */ |
2015 | if (nbytes >= sizeof(local_buffer)) { |
2016 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); |
2017 | if (buffer == NULL) |
2018 | return -ENOMEM; |
2019 | } |
2020 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
2021 | retval = -EFAULT; |
2022 | goto out; |
2023 | } |
2024 | |
2025 | buffer[nbytes] = 0; /* nul-terminate */ |
2026 | retval = cft->write_string(cgrp, cft, strstrip(buffer)); |
2027 | if (!retval) |
2028 | retval = nbytes; |
2029 | out: |
2030 | if (buffer != local_buffer) |
2031 | kfree(buffer); |
2032 | return retval; |
2033 | } |
2034 | |
2035 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
2036 | size_t nbytes, loff_t *ppos) |
2037 | { |
2038 | struct cftype *cft = __d_cft(file->f_dentry); |
2039 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
2040 | |
2041 | if (cgroup_is_removed(cgrp)) |
2042 | return -ENODEV; |
2043 | if (cft->write) |
2044 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
2045 | if (cft->write_u64 || cft->write_s64) |
2046 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); |
2047 | if (cft->write_string) |
2048 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); |
2049 | if (cft->trigger) { |
2050 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); |
2051 | return ret ? ret : nbytes; |
2052 | } |
2053 | return -EINVAL; |
2054 | } |
2055 | |
2056 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
2057 | struct file *file, |
2058 | char __user *buf, size_t nbytes, |
2059 | loff_t *ppos) |
2060 | { |
2061 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
2062 | u64 val = cft->read_u64(cgrp, cft); |
2063 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
2064 | |
2065 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); |
2066 | } |
2067 | |
2068 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
2069 | struct file *file, |
2070 | char __user *buf, size_t nbytes, |
2071 | loff_t *ppos) |
2072 | { |
2073 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
2074 | s64 val = cft->read_s64(cgrp, cft); |
2075 | int len = sprintf(tmp, "%lld\n", (long long) val); |
2076 | |
2077 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); |
2078 | } |
2079 | |
2080 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
2081 | size_t nbytes, loff_t *ppos) |
2082 | { |
2083 | struct cftype *cft = __d_cft(file->f_dentry); |
2084 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
2085 | |
2086 | if (cgroup_is_removed(cgrp)) |
2087 | return -ENODEV; |
2088 | |
2089 | if (cft->read) |
2090 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
2091 | if (cft->read_u64) |
2092 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); |
2093 | if (cft->read_s64) |
2094 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); |
2095 | return -EINVAL; |
2096 | } |
2097 | |
2098 | /* |
2099 | * seqfile ops/methods for returning structured data. Currently just |
2100 | * supports string->u64 maps, but can be extended in future. |
2101 | */ |
2102 | |
2103 | struct cgroup_seqfile_state { |
2104 | struct cftype *cft; |
2105 | struct cgroup *cgroup; |
2106 | }; |
2107 | |
2108 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) |
2109 | { |
2110 | struct seq_file *sf = cb->state; |
2111 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); |
2112 | } |
2113 | |
2114 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
2115 | { |
2116 | struct cgroup_seqfile_state *state = m->private; |
2117 | struct cftype *cft = state->cft; |
2118 | if (cft->read_map) { |
2119 | struct cgroup_map_cb cb = { |
2120 | .fill = cgroup_map_add, |
2121 | .state = m, |
2122 | }; |
2123 | return cft->read_map(state->cgroup, cft, &cb); |
2124 | } |
2125 | return cft->read_seq_string(state->cgroup, cft, m); |
2126 | } |
2127 | |
2128 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
2129 | { |
2130 | struct seq_file *seq = file->private_data; |
2131 | kfree(seq->private); |
2132 | return single_release(inode, file); |
2133 | } |
2134 | |
2135 | static const struct file_operations cgroup_seqfile_operations = { |
2136 | .read = seq_read, |
2137 | .write = cgroup_file_write, |
2138 | .llseek = seq_lseek, |
2139 | .release = cgroup_seqfile_release, |
2140 | }; |
2141 | |
2142 | static int cgroup_file_open(struct inode *inode, struct file *file) |
2143 | { |
2144 | int err; |
2145 | struct cftype *cft; |
2146 | |
2147 | err = generic_file_open(inode, file); |
2148 | if (err) |
2149 | return err; |
2150 | cft = __d_cft(file->f_dentry); |
2151 | |
2152 | if (cft->read_map || cft->read_seq_string) { |
2153 | struct cgroup_seqfile_state *state = |
2154 | kzalloc(sizeof(*state), GFP_USER); |
2155 | if (!state) |
2156 | return -ENOMEM; |
2157 | state->cft = cft; |
2158 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); |
2159 | file->f_op = &cgroup_seqfile_operations; |
2160 | err = single_open(file, cgroup_seqfile_show, state); |
2161 | if (err < 0) |
2162 | kfree(state); |
2163 | } else if (cft->open) |
2164 | err = cft->open(inode, file); |
2165 | else |
2166 | err = 0; |
2167 | |
2168 | return err; |
2169 | } |
2170 | |
2171 | static int cgroup_file_release(struct inode *inode, struct file *file) |
2172 | { |
2173 | struct cftype *cft = __d_cft(file->f_dentry); |
2174 | if (cft->release) |
2175 | return cft->release(inode, file); |
2176 | return 0; |
2177 | } |
2178 | |
2179 | /* |
2180 | * cgroup_rename - Only allow simple rename of directories in place. |
2181 | */ |
2182 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, |
2183 | struct inode *new_dir, struct dentry *new_dentry) |
2184 | { |
2185 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) |
2186 | return -ENOTDIR; |
2187 | if (new_dentry->d_inode) |
2188 | return -EEXIST; |
2189 | if (old_dir != new_dir) |
2190 | return -EIO; |
2191 | return simple_rename(old_dir, old_dentry, new_dir, new_dentry); |
2192 | } |
2193 | |
2194 | static const struct file_operations cgroup_file_operations = { |
2195 | .read = cgroup_file_read, |
2196 | .write = cgroup_file_write, |
2197 | .llseek = generic_file_llseek, |
2198 | .open = cgroup_file_open, |
2199 | .release = cgroup_file_release, |
2200 | }; |
2201 | |
2202 | static const struct inode_operations cgroup_dir_inode_operations = { |
2203 | .lookup = cgroup_lookup, |
2204 | .mkdir = cgroup_mkdir, |
2205 | .rmdir = cgroup_rmdir, |
2206 | .rename = cgroup_rename, |
2207 | }; |
2208 | |
2209 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) |
2210 | { |
2211 | if (dentry->d_name.len > NAME_MAX) |
2212 | return ERR_PTR(-ENAMETOOLONG); |
2213 | d_add(dentry, NULL); |
2214 | return NULL; |
2215 | } |
2216 | |
2217 | /* |
2218 | * Check if a file is a control file |
2219 | */ |
2220 | static inline struct cftype *__file_cft(struct file *file) |
2221 | { |
2222 | if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations) |
2223 | return ERR_PTR(-EINVAL); |
2224 | return __d_cft(file->f_dentry); |
2225 | } |
2226 | |
2227 | static int cgroup_create_file(struct dentry *dentry, mode_t mode, |
2228 | struct super_block *sb) |
2229 | { |
2230 | struct inode *inode; |
2231 | |
2232 | if (!dentry) |
2233 | return -ENOENT; |
2234 | if (dentry->d_inode) |
2235 | return -EEXIST; |
2236 | |
2237 | inode = cgroup_new_inode(mode, sb); |
2238 | if (!inode) |
2239 | return -ENOMEM; |
2240 | |
2241 | if (S_ISDIR(mode)) { |
2242 | inode->i_op = &cgroup_dir_inode_operations; |
2243 | inode->i_fop = &simple_dir_operations; |
2244 | |
2245 | /* start off with i_nlink == 2 (for "." entry) */ |
2246 | inc_nlink(inode); |
2247 | |
2248 | /* start with the directory inode held, so that we can |
2249 | * populate it without racing with another mkdir */ |
2250 | mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
2251 | } else if (S_ISREG(mode)) { |
2252 | inode->i_size = 0; |
2253 | inode->i_fop = &cgroup_file_operations; |
2254 | } |
2255 | d_instantiate(dentry, inode); |
2256 | dget(dentry); /* Extra count - pin the dentry in core */ |
2257 | return 0; |
2258 | } |
2259 | |
2260 | /* |
2261 | * cgroup_create_dir - create a directory for an object. |
2262 | * @cgrp: the cgroup we create the directory for. It must have a valid |
2263 | * ->parent field. And we are going to fill its ->dentry field. |
2264 | * @dentry: dentry of the new cgroup |
2265 | * @mode: mode to set on new directory. |
2266 | */ |
2267 | static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry, |
2268 | mode_t mode) |
2269 | { |
2270 | struct dentry *parent; |
2271 | int error = 0; |
2272 | |
2273 | parent = cgrp->parent->dentry; |
2274 | error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb); |
2275 | if (!error) { |
2276 | dentry->d_fsdata = cgrp; |
2277 | inc_nlink(parent->d_inode); |
2278 | rcu_assign_pointer(cgrp->dentry, dentry); |
2279 | dget(dentry); |
2280 | } |
2281 | dput(dentry); |
2282 | |
2283 | return error; |
2284 | } |
2285 | |
2286 | /** |
2287 | * cgroup_file_mode - deduce file mode of a control file |
2288 | * @cft: the control file in question |
2289 | * |
2290 | * returns cft->mode if ->mode is not 0 |
2291 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler |
2292 | * returns S_IRUGO if it has only a read handler |
2293 | * returns S_IWUSR if it has only a write hander |
2294 | */ |
2295 | static mode_t cgroup_file_mode(const struct cftype *cft) |
2296 | { |
2297 | mode_t mode = 0; |
2298 | |
2299 | if (cft->mode) |
2300 | return cft->mode; |
2301 | |
2302 | if (cft->read || cft->read_u64 || cft->read_s64 || |
2303 | cft->read_map || cft->read_seq_string) |
2304 | mode |= S_IRUGO; |
2305 | |
2306 | if (cft->write || cft->write_u64 || cft->write_s64 || |
2307 | cft->write_string || cft->trigger) |
2308 | mode |= S_IWUSR; |
2309 | |
2310 | return mode; |
2311 | } |
2312 | |
2313 | int cgroup_add_file(struct cgroup *cgrp, |
2314 | struct cgroup_subsys *subsys, |
2315 | const struct cftype *cft) |
2316 | { |
2317 | struct dentry *dir = cgrp->dentry; |
2318 | struct dentry *dentry; |
2319 | int error; |
2320 | mode_t mode; |
2321 | |
2322 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; |
2323 | if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { |
2324 | strcpy(name, subsys->name); |
2325 | strcat(name, "."); |
2326 | } |
2327 | strcat(name, cft->name); |
2328 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); |
2329 | dentry = lookup_one_len(name, dir, strlen(name)); |
2330 | if (!IS_ERR(dentry)) { |
2331 | mode = cgroup_file_mode(cft); |
2332 | error = cgroup_create_file(dentry, mode | S_IFREG, |
2333 | cgrp->root->sb); |
2334 | if (!error) |
2335 | dentry->d_fsdata = (void *)cft; |
2336 | dput(dentry); |
2337 | } else |
2338 | error = PTR_ERR(dentry); |
2339 | return error; |
2340 | } |
2341 | EXPORT_SYMBOL_GPL(cgroup_add_file); |
2342 | |
2343 | int cgroup_add_files(struct cgroup *cgrp, |
2344 | struct cgroup_subsys *subsys, |
2345 | const struct cftype cft[], |
2346 | int count) |
2347 | { |
2348 | int i, err; |
2349 | for (i = 0; i < count; i++) { |
2350 | err = cgroup_add_file(cgrp, subsys, &cft[i]); |
2351 | if (err) |
2352 | return err; |
2353 | } |
2354 | return 0; |
2355 | } |
2356 | EXPORT_SYMBOL_GPL(cgroup_add_files); |
2357 | |
2358 | /** |
2359 | * cgroup_task_count - count the number of tasks in a cgroup. |
2360 | * @cgrp: the cgroup in question |
2361 | * |
2362 | * Return the number of tasks in the cgroup. |
2363 | */ |
2364 | int cgroup_task_count(const struct cgroup *cgrp) |
2365 | { |
2366 | int count = 0; |
2367 | struct cg_cgroup_link *link; |
2368 | |
2369 | read_lock(&css_set_lock); |
2370 | list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { |
2371 | count += atomic_read(&link->cg->refcount); |
2372 | } |
2373 | read_unlock(&css_set_lock); |
2374 | return count; |
2375 | } |
2376 | |
2377 | /* |
2378 | * Advance a list_head iterator. The iterator should be positioned at |
2379 | * the start of a css_set |
2380 | */ |
2381 | static void cgroup_advance_iter(struct cgroup *cgrp, |
2382 | struct cgroup_iter *it) |
2383 | { |
2384 | struct list_head *l = it->cg_link; |
2385 | struct cg_cgroup_link *link; |
2386 | struct css_set *cg; |
2387 | |
2388 | /* Advance to the next non-empty css_set */ |
2389 | do { |
2390 | l = l->next; |
2391 | if (l == &cgrp->css_sets) { |
2392 | it->cg_link = NULL; |
2393 | return; |
2394 | } |
2395 | link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); |
2396 | cg = link->cg; |
2397 | } while (list_empty(&cg->tasks)); |
2398 | it->cg_link = l; |
2399 | it->task = cg->tasks.next; |
2400 | } |
2401 | |
2402 | /* |
2403 | * To reduce the fork() overhead for systems that are not actually |
2404 | * using their cgroups capability, we don't maintain the lists running |
2405 | * through each css_set to its tasks until we see the list actually |
2406 | * used - in other words after the first call to cgroup_iter_start(). |
2407 | * |
2408 | * The tasklist_lock is not held here, as do_each_thread() and |
2409 | * while_each_thread() are protected by RCU. |
2410 | */ |
2411 | static void cgroup_enable_task_cg_lists(void) |
2412 | { |
2413 | struct task_struct *p, *g; |
2414 | write_lock(&css_set_lock); |
2415 | use_task_css_set_links = 1; |
2416 | do_each_thread(g, p) { |
2417 | task_lock(p); |
2418 | /* |
2419 | * We should check if the process is exiting, otherwise |
2420 | * it will race with cgroup_exit() in that the list |
2421 | * entry won't be deleted though the process has exited. |
2422 | */ |
2423 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) |
2424 | list_add(&p->cg_list, &p->cgroups->tasks); |
2425 | task_unlock(p); |
2426 | } while_each_thread(g, p); |
2427 | write_unlock(&css_set_lock); |
2428 | } |
2429 | |
2430 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
2431 | { |
2432 | /* |
2433 | * The first time anyone tries to iterate across a cgroup, |
2434 | * we need to enable the list linking each css_set to its |
2435 | * tasks, and fix up all existing tasks. |
2436 | */ |
2437 | if (!use_task_css_set_links) |
2438 | cgroup_enable_task_cg_lists(); |
2439 | |
2440 | read_lock(&css_set_lock); |
2441 | it->cg_link = &cgrp->css_sets; |
2442 | cgroup_advance_iter(cgrp, it); |
2443 | } |
2444 | |
2445 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
2446 | struct cgroup_iter *it) |
2447 | { |
2448 | struct task_struct *res; |
2449 | struct list_head *l = it->task; |
2450 | struct cg_cgroup_link *link; |
2451 | |
2452 | /* If the iterator cg is NULL, we have no tasks */ |
2453 | if (!it->cg_link) |
2454 | return NULL; |
2455 | res = list_entry(l, struct task_struct, cg_list); |
2456 | /* Advance iterator to find next entry */ |
2457 | l = l->next; |
2458 | link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); |
2459 | if (l == &link->cg->tasks) { |
2460 | /* We reached the end of this task list - move on to |
2461 | * the next cg_cgroup_link */ |
2462 | cgroup_advance_iter(cgrp, it); |
2463 | } else { |
2464 | it->task = l; |
2465 | } |
2466 | return res; |
2467 | } |
2468 | |
2469 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
2470 | { |
2471 | read_unlock(&css_set_lock); |
2472 | } |
2473 | |
2474 | static inline int started_after_time(struct task_struct *t1, |
2475 | struct timespec *time, |
2476 | struct task_struct *t2) |
2477 | { |
2478 | int start_diff = timespec_compare(&t1->start_time, time); |
2479 | if (start_diff > 0) { |
2480 | return 1; |
2481 | } else if (start_diff < 0) { |
2482 | return 0; |
2483 | } else { |
2484 | /* |
2485 | * Arbitrarily, if two processes started at the same |
2486 | * time, we'll say that the lower pointer value |
2487 | * started first. Note that t2 may have exited by now |
2488 | * so this may not be a valid pointer any longer, but |
2489 | * that's fine - it still serves to distinguish |
2490 | * between two tasks started (effectively) simultaneously. |
2491 | */ |
2492 | return t1 > t2; |
2493 | } |
2494 | } |
2495 | |
2496 | /* |
2497 | * This function is a callback from heap_insert() and is used to order |
2498 | * the heap. |
2499 | * In this case we order the heap in descending task start time. |
2500 | */ |
2501 | static inline int started_after(void *p1, void *p2) |
2502 | { |
2503 | struct task_struct *t1 = p1; |
2504 | struct task_struct *t2 = p2; |
2505 | return started_after_time(t1, &t2->start_time, t2); |
2506 | } |
2507 | |
2508 | /** |
2509 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup |
2510 | * @scan: struct cgroup_scanner containing arguments for the scan |
2511 | * |
2512 | * Arguments include pointers to callback functions test_task() and |
2513 | * process_task(). |
2514 | * Iterate through all the tasks in a cgroup, calling test_task() for each, |
2515 | * and if it returns true, call process_task() for it also. |
2516 | * The test_task pointer may be NULL, meaning always true (select all tasks). |
2517 | * Effectively duplicates cgroup_iter_{start,next,end}() |
2518 | * but does not lock css_set_lock for the call to process_task(). |
2519 | * The struct cgroup_scanner may be embedded in any structure of the caller's |
2520 | * creation. |
2521 | * It is guaranteed that process_task() will act on every task that |
2522 | * is a member of the cgroup for the duration of this call. This |
2523 | * function may or may not call process_task() for tasks that exit |
2524 | * or move to a different cgroup during the call, or are forked or |
2525 | * move into the cgroup during the call. |
2526 | * |
2527 | * Note that test_task() may be called with locks held, and may in some |
2528 | * situations be called multiple times for the same task, so it should |
2529 | * be cheap. |
2530 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been |
2531 | * pre-allocated and will be used for heap operations (and its "gt" member will |
2532 | * be overwritten), else a temporary heap will be used (allocation of which |
2533 | * may cause this function to fail). |
2534 | */ |
2535 | int cgroup_scan_tasks(struct cgroup_scanner *scan) |
2536 | { |
2537 | int retval, i; |
2538 | struct cgroup_iter it; |
2539 | struct task_struct *p, *dropped; |
2540 | /* Never dereference latest_task, since it's not refcounted */ |
2541 | struct task_struct *latest_task = NULL; |
2542 | struct ptr_heap tmp_heap; |
2543 | struct ptr_heap *heap; |
2544 | struct timespec latest_time = { 0, 0 }; |
2545 | |
2546 | if (scan->heap) { |
2547 | /* The caller supplied our heap and pre-allocated its memory */ |
2548 | heap = scan->heap; |
2549 | heap->gt = &started_after; |
2550 | } else { |
2551 | /* We need to allocate our own heap memory */ |
2552 | heap = &tmp_heap; |
2553 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); |
2554 | if (retval) |
2555 | /* cannot allocate the heap */ |
2556 | return retval; |
2557 | } |
2558 | |
2559 | again: |
2560 | /* |
2561 | * Scan tasks in the cgroup, using the scanner's "test_task" callback |
2562 | * to determine which are of interest, and using the scanner's |
2563 | * "process_task" callback to process any of them that need an update. |
2564 | * Since we don't want to hold any locks during the task updates, |
2565 | * gather tasks to be processed in a heap structure. |
2566 | * The heap is sorted by descending task start time. |
2567 | * If the statically-sized heap fills up, we overflow tasks that |
2568 | * started later, and in future iterations only consider tasks that |
2569 | * started after the latest task in the previous pass. This |
2570 | * guarantees forward progress and that we don't miss any tasks. |
2571 | */ |
2572 | heap->size = 0; |
2573 | cgroup_iter_start(scan->cg, &it); |
2574 | while ((p = cgroup_iter_next(scan->cg, &it))) { |
2575 | /* |
2576 | * Only affect tasks that qualify per the caller's callback, |
2577 | * if he provided one |
2578 | */ |
2579 | if (scan->test_task && !scan->test_task(p, scan)) |
2580 | continue; |
2581 | /* |
2582 | * Only process tasks that started after the last task |
2583 | * we processed |
2584 | */ |
2585 | if (!started_after_time(p, &latest_time, latest_task)) |
2586 | continue; |
2587 | dropped = heap_insert(heap, p); |
2588 | if (dropped == NULL) { |
2589 | /* |
2590 | * The new task was inserted; the heap wasn't |
2591 | * previously full |
2592 | */ |
2593 | get_task_struct(p); |
2594 | } else if (dropped != p) { |
2595 | /* |
2596 | * The new task was inserted, and pushed out a |
2597 | * different task |
2598 | */ |
2599 | get_task_struct(p); |
2600 | put_task_struct(dropped); |
2601 | } |
2602 | /* |
2603 | * Else the new task was newer than anything already in |
2604 | * the heap and wasn't inserted |
2605 | */ |
2606 | } |
2607 | cgroup_iter_end(scan->cg, &it); |
2608 | |
2609 | if (heap->size) { |
2610 | for (i = 0; i < heap->size; i++) { |
2611 | struct task_struct *q = heap->ptrs[i]; |
2612 | if (i == 0) { |
2613 | latest_time = q->start_time; |
2614 | latest_task = q; |
2615 | } |
2616 | /* Process the task per the caller's callback */ |
2617 | scan->process_task(q, scan); |
2618 | put_task_struct(q); |
2619 | } |
2620 | /* |
2621 | * If we had to process any tasks at all, scan again |
2622 | * in case some of them were in the middle of forking |
2623 | * children that didn't get processed. |
2624 | * Not the most efficient way to do it, but it avoids |
2625 | * having to take callback_mutex in the fork path |
2626 | */ |
2627 | goto again; |
2628 | } |
2629 | if (heap == &tmp_heap) |
2630 | heap_free(&tmp_heap); |
2631 | return 0; |
2632 | } |
2633 | |
2634 | /* |
2635 | * Stuff for reading the 'tasks'/'procs' files. |
2636 | * |
2637 | * Reading this file can return large amounts of data if a cgroup has |
2638 | * *lots* of attached tasks. So it may need several calls to read(), |
2639 | * but we cannot guarantee that the information we produce is correct |
2640 | * unless we produce it entirely atomically. |
2641 | * |
2642 | */ |
2643 | |
2644 | /* |
2645 | * The following two functions "fix" the issue where there are more pids |
2646 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. |
2647 | * TODO: replace with a kernel-wide solution to this problem |
2648 | */ |
2649 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) |
2650 | static void *pidlist_allocate(int count) |
2651 | { |
2652 | if (PIDLIST_TOO_LARGE(count)) |
2653 | return vmalloc(count * sizeof(pid_t)); |
2654 | else |
2655 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); |
2656 | } |
2657 | static void pidlist_free(void *p) |
2658 | { |
2659 | if (is_vmalloc_addr(p)) |
2660 | vfree(p); |
2661 | else |
2662 | kfree(p); |
2663 | } |
2664 | static void *pidlist_resize(void *p, int newcount) |
2665 | { |
2666 | void *newlist; |
2667 | /* note: if new alloc fails, old p will still be valid either way */ |
2668 | if (is_vmalloc_addr(p)) { |
2669 | newlist = vmalloc(newcount * sizeof(pid_t)); |
2670 | if (!newlist) |
2671 | return NULL; |
2672 | memcpy(newlist, p, newcount * sizeof(pid_t)); |
2673 | vfree(p); |
2674 | } else { |
2675 | newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); |
2676 | } |
2677 | return newlist; |
2678 | } |
2679 | |
2680 | /* |
2681 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
2682 | * If the new stripped list is sufficiently smaller and there's enough memory |
2683 | * to allocate a new buffer, will let go of the unneeded memory. Returns the |
2684 | * number of unique elements. |
2685 | */ |
2686 | /* is the size difference enough that we should re-allocate the array? */ |
2687 | #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) |
2688 | static int pidlist_uniq(pid_t **p, int length) |
2689 | { |
2690 | int src, dest = 1; |
2691 | pid_t *list = *p; |
2692 | pid_t *newlist; |
2693 | |
2694 | /* |
2695 | * we presume the 0th element is unique, so i starts at 1. trivial |
2696 | * edge cases first; no work needs to be done for either |
2697 | */ |
2698 | if (length == 0 || length == 1) |
2699 | return length; |
2700 | /* src and dest walk down the list; dest counts unique elements */ |
2701 | for (src = 1; src < length; src++) { |
2702 | /* find next unique element */ |
2703 | while (list[src] == list[src-1]) { |
2704 | src++; |
2705 | if (src == length) |
2706 | goto after; |
2707 | } |
2708 | /* dest always points to where the next unique element goes */ |
2709 | list[dest] = list[src]; |
2710 | dest++; |
2711 | } |
2712 | after: |
2713 | /* |
2714 | * if the length difference is large enough, we want to allocate a |
2715 | * smaller buffer to save memory. if this fails due to out of memory, |
2716 | * we'll just stay with what we've got. |
2717 | */ |
2718 | if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { |
2719 | newlist = pidlist_resize(list, dest); |
2720 | if (newlist) |
2721 | *p = newlist; |
2722 | } |
2723 | return dest; |
2724 | } |
2725 | |
2726 | static int cmppid(const void *a, const void *b) |
2727 | { |
2728 | return *(pid_t *)a - *(pid_t *)b; |
2729 | } |
2730 | |
2731 | /* |
2732 | * find the appropriate pidlist for our purpose (given procs vs tasks) |
2733 | * returns with the lock on that pidlist already held, and takes care |
2734 | * of the use count, or returns NULL with no locks held if we're out of |
2735 | * memory. |
2736 | */ |
2737 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
2738 | enum cgroup_filetype type) |
2739 | { |
2740 | struct cgroup_pidlist *l; |
2741 | /* don't need task_nsproxy() if we're looking at ourself */ |
2742 | struct pid_namespace *ns = current->nsproxy->pid_ns; |
2743 | |
2744 | /* |
2745 | * We can't drop the pidlist_mutex before taking the l->mutex in case |
2746 | * the last ref-holder is trying to remove l from the list at the same |
2747 | * time. Holding the pidlist_mutex precludes somebody taking whichever |
2748 | * list we find out from under us - compare release_pid_array(). |
2749 | */ |
2750 | mutex_lock(&cgrp->pidlist_mutex); |
2751 | list_for_each_entry(l, &cgrp->pidlists, links) { |
2752 | if (l->key.type == type && l->key.ns == ns) { |
2753 | /* make sure l doesn't vanish out from under us */ |
2754 | down_write(&l->mutex); |
2755 | mutex_unlock(&cgrp->pidlist_mutex); |
2756 | return l; |
2757 | } |
2758 | } |
2759 | /* entry not found; create a new one */ |
2760 | l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
2761 | if (!l) { |
2762 | mutex_unlock(&cgrp->pidlist_mutex); |
2763 | return l; |
2764 | } |
2765 | init_rwsem(&l->mutex); |
2766 | down_write(&l->mutex); |
2767 | l->key.type = type; |
2768 | l->key.ns = get_pid_ns(ns); |
2769 | l->use_count = 0; /* don't increment here */ |
2770 | l->list = NULL; |
2771 | l->owner = cgrp; |
2772 | list_add(&l->links, &cgrp->pidlists); |
2773 | mutex_unlock(&cgrp->pidlist_mutex); |
2774 | return l; |
2775 | } |
2776 | |
2777 | /* |
2778 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids |
2779 | */ |
2780 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
2781 | struct cgroup_pidlist **lp) |
2782 | { |
2783 | pid_t *array; |
2784 | int length; |
2785 | int pid, n = 0; /* used for populating the array */ |
2786 | struct cgroup_iter it; |
2787 | struct task_struct *tsk; |
2788 | struct cgroup_pidlist *l; |
2789 | |
2790 | /* |
2791 | * If cgroup gets more users after we read count, we won't have |
2792 | * enough space - tough. This race is indistinguishable to the |
2793 | * caller from the case that the additional cgroup users didn't |
2794 | * show up until sometime later on. |
2795 | */ |
2796 | length = cgroup_task_count(cgrp); |
2797 | array = pidlist_allocate(length); |
2798 | if (!array) |
2799 | return -ENOMEM; |
2800 | /* now, populate the array */ |
2801 | cgroup_iter_start(cgrp, &it); |
2802 | while ((tsk = cgroup_iter_next(cgrp, &it))) { |
2803 | if (unlikely(n == length)) |
2804 | break; |
2805 | /* get tgid or pid for procs or tasks file respectively */ |
2806 | if (type == CGROUP_FILE_PROCS) |
2807 | pid = task_tgid_vnr(tsk); |
2808 | else |
2809 | pid = task_pid_vnr(tsk); |
2810 | if (pid > 0) /* make sure to only use valid results */ |
2811 | array[n++] = pid; |
2812 | } |
2813 | cgroup_iter_end(cgrp, &it); |
2814 | length = n; |
2815 | /* now sort & (if procs) strip out duplicates */ |
2816 | sort(array, length, sizeof(pid_t), cmppid, NULL); |
2817 | if (type == CGROUP_FILE_PROCS) |
2818 | length = pidlist_uniq(&array, length); |
2819 | l = cgroup_pidlist_find(cgrp, type); |
2820 | if (!l) { |
2821 | pidlist_free(array); |
2822 | return -ENOMEM; |
2823 | } |
2824 | /* store array, freeing old if necessary - lock already held */ |
2825 | pidlist_free(l->list); |
2826 | l->list = array; |
2827 | l->length = length; |
2828 | l->use_count++; |
2829 | up_write(&l->mutex); |
2830 | *lp = l; |
2831 | return 0; |
2832 | } |
2833 | |
2834 | /** |
2835 | * cgroupstats_build - build and fill cgroupstats |
2836 | * @stats: cgroupstats to fill information into |
2837 | * @dentry: A dentry entry belonging to the cgroup for which stats have |
2838 | * been requested. |
2839 | * |
2840 | * Build and fill cgroupstats so that taskstats can export it to user |
2841 | * space. |
2842 | */ |
2843 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) |
2844 | { |
2845 | int ret = -EINVAL; |
2846 | struct cgroup *cgrp; |
2847 | struct cgroup_iter it; |
2848 | struct task_struct *tsk; |
2849 | |
2850 | /* |
2851 | * Validate dentry by checking the superblock operations, |
2852 | * and make sure it's a directory. |
2853 | */ |
2854 | if (dentry->d_sb->s_op != &cgroup_ops || |
2855 | !S_ISDIR(dentry->d_inode->i_mode)) |
2856 | goto err; |
2857 | |
2858 | ret = 0; |
2859 | cgrp = dentry->d_fsdata; |
2860 | |
2861 | cgroup_iter_start(cgrp, &it); |
2862 | while ((tsk = cgroup_iter_next(cgrp, &it))) { |
2863 | switch (tsk->state) { |
2864 | case TASK_RUNNING: |
2865 | stats->nr_running++; |
2866 | break; |
2867 | case TASK_INTERRUPTIBLE: |
2868 | stats->nr_sleeping++; |
2869 | break; |
2870 | case TASK_UNINTERRUPTIBLE: |
2871 | stats->nr_uninterruptible++; |
2872 | break; |
2873 | case TASK_STOPPED: |
2874 | stats->nr_stopped++; |
2875 | break; |
2876 | default: |
2877 | if (delayacct_is_task_waiting_on_io(tsk)) |
2878 | stats->nr_io_wait++; |
2879 | break; |
2880 | } |
2881 | } |
2882 | cgroup_iter_end(cgrp, &it); |
2883 | |
2884 | err: |
2885 | return ret; |
2886 | } |
2887 | |
2888 | |
2889 | /* |
2890 | * seq_file methods for the tasks/procs files. The seq_file position is the |
2891 | * next pid to display; the seq_file iterator is a pointer to the pid |
2892 | * in the cgroup->l->list array. |
2893 | */ |
2894 | |
2895 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
2896 | { |
2897 | /* |
2898 | * Initially we receive a position value that corresponds to |
2899 | * one more than the last pid shown (or 0 on the first call or |
2900 | * after a seek to the start). Use a binary-search to find the |
2901 | * next pid to display, if any |
2902 | */ |
2903 | struct cgroup_pidlist *l = s->private; |
2904 | int index = 0, pid = *pos; |
2905 | int *iter; |
2906 | |
2907 | down_read(&l->mutex); |
2908 | if (pid) { |
2909 | int end = l->length; |
2910 | |
2911 | while (index < end) { |
2912 | int mid = (index + end) / 2; |
2913 | if (l->list[mid] == pid) { |
2914 | index = mid; |
2915 | break; |
2916 | } else if (l->list[mid] <= pid) |
2917 | index = mid + 1; |
2918 | else |
2919 | end = mid; |
2920 | } |
2921 | } |
2922 | /* If we're off the end of the array, we're done */ |
2923 | if (index >= l->length) |
2924 | return NULL; |
2925 | /* Update the abstract position to be the actual pid that we found */ |
2926 | iter = l->list + index; |
2927 | *pos = *iter; |
2928 | return iter; |
2929 | } |
2930 | |
2931 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
2932 | { |
2933 | struct cgroup_pidlist *l = s->private; |
2934 | up_read(&l->mutex); |
2935 | } |
2936 | |
2937 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
2938 | { |
2939 | struct cgroup_pidlist *l = s->private; |
2940 | pid_t *p = v; |
2941 | pid_t *end = l->list + l->length; |
2942 | /* |
2943 | * Advance to the next pid in the array. If this goes off the |
2944 | * end, we're done |
2945 | */ |
2946 | p++; |
2947 | if (p >= end) { |
2948 | return NULL; |
2949 | } else { |
2950 | *pos = *p; |
2951 | return p; |
2952 | } |
2953 | } |
2954 | |
2955 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
2956 | { |
2957 | return seq_printf(s, "%d\n", *(int *)v); |
2958 | } |
2959 | |
2960 | /* |
2961 | * seq_operations functions for iterating on pidlists through seq_file - |
2962 | * independent of whether it's tasks or procs |
2963 | */ |
2964 | static const struct seq_operations cgroup_pidlist_seq_operations = { |
2965 | .start = cgroup_pidlist_start, |
2966 | .stop = cgroup_pidlist_stop, |
2967 | .next = cgroup_pidlist_next, |
2968 | .show = cgroup_pidlist_show, |
2969 | }; |
2970 | |
2971 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
2972 | { |
2973 | /* |
2974 | * the case where we're the last user of this particular pidlist will |
2975 | * have us remove it from the cgroup's list, which entails taking the |
2976 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> |
2977 | * pidlist_mutex, we have to take pidlist_mutex first. |
2978 | */ |
2979 | mutex_lock(&l->owner->pidlist_mutex); |
2980 | down_write(&l->mutex); |
2981 | BUG_ON(!l->use_count); |
2982 | if (!--l->use_count) { |
2983 | /* we're the last user if refcount is 0; remove and free */ |
2984 | list_del(&l->links); |
2985 | mutex_unlock(&l->owner->pidlist_mutex); |
2986 | pidlist_free(l->list); |
2987 | put_pid_ns(l->key.ns); |
2988 | up_write(&l->mutex); |
2989 | kfree(l); |
2990 | return; |
2991 | } |
2992 | mutex_unlock(&l->owner->pidlist_mutex); |
2993 | up_write(&l->mutex); |
2994 | } |
2995 | |
2996 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
2997 | { |
2998 | struct cgroup_pidlist *l; |
2999 | if (!(file->f_mode & FMODE_READ)) |
3000 | return 0; |
3001 | /* |
3002 | * the seq_file will only be initialized if the file was opened for |
3003 | * reading; hence we check if it's not null only in that case. |
3004 | */ |
3005 | l = ((struct seq_file *)file->private_data)->private; |
3006 | cgroup_release_pid_array(l); |
3007 | return seq_release(inode, file); |
3008 | } |
3009 | |
3010 | static const struct file_operations cgroup_pidlist_operations = { |
3011 | .read = seq_read, |
3012 | .llseek = seq_lseek, |
3013 | .write = cgroup_file_write, |
3014 | .release = cgroup_pidlist_release, |
3015 | }; |
3016 | |
3017 | /* |
3018 | * The following functions handle opens on a file that displays a pidlist |
3019 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's |
3020 | * in the cgroup. |
3021 | */ |
3022 | /* helper function for the two below it */ |
3023 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
3024 | { |
3025 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
3026 | struct cgroup_pidlist *l; |
3027 | int retval; |
3028 | |
3029 | /* Nothing to do for write-only files */ |
3030 | if (!(file->f_mode & FMODE_READ)) |
3031 | return 0; |
3032 | |
3033 | /* have the array populated */ |
3034 | retval = pidlist_array_load(cgrp, type, &l); |
3035 | if (retval) |
3036 | return retval; |
3037 | /* configure file information */ |
3038 | file->f_op = &cgroup_pidlist_operations; |
3039 | |
3040 | retval = seq_open(file, &cgroup_pidlist_seq_operations); |
3041 | if (retval) { |
3042 | cgroup_release_pid_array(l); |
3043 | return retval; |
3044 | } |
3045 | ((struct seq_file *)file->private_data)->private = l; |
3046 | return 0; |
3047 | } |
3048 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
3049 | { |
3050 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
3051 | } |
3052 | static int cgroup_procs_open(struct inode *unused, struct file *file) |
3053 | { |
3054 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
3055 | } |
3056 | |
3057 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
3058 | struct cftype *cft) |
3059 | { |
3060 | return notify_on_release(cgrp); |
3061 | } |
3062 | |
3063 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
3064 | struct cftype *cft, |
3065 | u64 val) |
3066 | { |
3067 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); |
3068 | if (val) |
3069 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
3070 | else |
3071 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
3072 | return 0; |
3073 | } |
3074 | |
3075 | /* |
3076 | * Unregister event and free resources. |
3077 | * |
3078 | * Gets called from workqueue. |
3079 | */ |
3080 | static void cgroup_event_remove(struct work_struct *work) |
3081 | { |
3082 | struct cgroup_event *event = container_of(work, struct cgroup_event, |
3083 | remove); |
3084 | struct cgroup *cgrp = event->cgrp; |
3085 | |
3086 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3087 | |
3088 | eventfd_ctx_put(event->eventfd); |
3089 | kfree(event); |
3090 | dput(cgrp->dentry); |
3091 | } |
3092 | |
3093 | /* |
3094 | * Gets called on POLLHUP on eventfd when user closes it. |
3095 | * |
3096 | * Called with wqh->lock held and interrupts disabled. |
3097 | */ |
3098 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, |
3099 | int sync, void *key) |
3100 | { |
3101 | struct cgroup_event *event = container_of(wait, |
3102 | struct cgroup_event, wait); |
3103 | struct cgroup *cgrp = event->cgrp; |
3104 | unsigned long flags = (unsigned long)key; |
3105 | |
3106 | if (flags & POLLHUP) { |
3107 | __remove_wait_queue(event->wqh, &event->wait); |
3108 | spin_lock(&cgrp->event_list_lock); |
3109 | list_del(&event->list); |
3110 | spin_unlock(&cgrp->event_list_lock); |
3111 | /* |
3112 | * We are in atomic context, but cgroup_event_remove() may |
3113 | * sleep, so we have to call it in workqueue. |
3114 | */ |
3115 | schedule_work(&event->remove); |
3116 | } |
3117 | |
3118 | return 0; |
3119 | } |
3120 | |
3121 | static void cgroup_event_ptable_queue_proc(struct file *file, |
3122 | wait_queue_head_t *wqh, poll_table *pt) |
3123 | { |
3124 | struct cgroup_event *event = container_of(pt, |
3125 | struct cgroup_event, pt); |
3126 | |
3127 | event->wqh = wqh; |
3128 | add_wait_queue(wqh, &event->wait); |
3129 | } |
3130 | |
3131 | /* |
3132 | * Parse input and register new cgroup event handler. |
3133 | * |
3134 | * Input must be in format '<event_fd> <control_fd> <args>'. |
3135 | * Interpretation of args is defined by control file implementation. |
3136 | */ |
3137 | static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, |
3138 | const char *buffer) |
3139 | { |
3140 | struct cgroup_event *event = NULL; |
3141 | unsigned int efd, cfd; |
3142 | struct file *efile = NULL; |
3143 | struct file *cfile = NULL; |
3144 | char *endp; |
3145 | int ret; |
3146 | |
3147 | efd = simple_strtoul(buffer, &endp, 10); |
3148 | if (*endp != ' ') |
3149 | return -EINVAL; |
3150 | buffer = endp + 1; |
3151 | |
3152 | cfd = simple_strtoul(buffer, &endp, 10); |
3153 | if ((*endp != ' ') && (*endp != '\0')) |
3154 | return -EINVAL; |
3155 | buffer = endp + 1; |
3156 | |
3157 | event = kzalloc(sizeof(*event), GFP_KERNEL); |
3158 | if (!event) |
3159 | return -ENOMEM; |
3160 | event->cgrp = cgrp; |
3161 | INIT_LIST_HEAD(&event->list); |
3162 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); |
3163 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); |
3164 | INIT_WORK(&event->remove, cgroup_event_remove); |
3165 | |
3166 | efile = eventfd_fget(efd); |
3167 | if (IS_ERR(efile)) { |
3168 | ret = PTR_ERR(efile); |
3169 | goto fail; |
3170 | } |
3171 | |
3172 | event->eventfd = eventfd_ctx_fileget(efile); |
3173 | if (IS_ERR(event->eventfd)) { |
3174 | ret = PTR_ERR(event->eventfd); |
3175 | goto fail; |
3176 | } |
3177 | |
3178 | cfile = fget(cfd); |
3179 | if (!cfile) { |
3180 | ret = -EBADF; |
3181 | goto fail; |
3182 | } |
3183 | |
3184 | /* the process need read permission on control file */ |
3185 | ret = file_permission(cfile, MAY_READ); |
3186 | if (ret < 0) |
3187 | goto fail; |
3188 | |
3189 | event->cft = __file_cft(cfile); |
3190 | if (IS_ERR(event->cft)) { |
3191 | ret = PTR_ERR(event->cft); |
3192 | goto fail; |
3193 | } |
3194 | |
3195 | if (!event->cft->register_event || !event->cft->unregister_event) { |
3196 | ret = -EINVAL; |
3197 | goto fail; |
3198 | } |
3199 | |
3200 | ret = event->cft->register_event(cgrp, event->cft, |
3201 | event->eventfd, buffer); |
3202 | if (ret) |
3203 | goto fail; |
3204 | |
3205 | if (efile->f_op->poll(efile, &event->pt) & POLLHUP) { |
3206 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3207 | ret = 0; |
3208 | goto fail; |
3209 | } |
3210 | |
3211 | /* |
3212 | * Events should be removed after rmdir of cgroup directory, but before |
3213 | * destroying subsystem state objects. Let's take reference to cgroup |
3214 | * directory dentry to do that. |
3215 | */ |
3216 | dget(cgrp->dentry); |
3217 | |
3218 | spin_lock(&cgrp->event_list_lock); |
3219 | list_add(&event->list, &cgrp->event_list); |
3220 | spin_unlock(&cgrp->event_list_lock); |
3221 | |
3222 | fput(cfile); |
3223 | fput(efile); |
3224 | |
3225 | return 0; |
3226 | |
3227 | fail: |
3228 | if (cfile) |
3229 | fput(cfile); |
3230 | |
3231 | if (event && event->eventfd && !IS_ERR(event->eventfd)) |
3232 | eventfd_ctx_put(event->eventfd); |
3233 | |
3234 | if (!IS_ERR_OR_NULL(efile)) |
3235 | fput(efile); |
3236 | |
3237 | kfree(event); |
3238 | |
3239 | return ret; |
3240 | } |
3241 | |
3242 | static u64 cgroup_clone_children_read(struct cgroup *cgrp, |
3243 | struct cftype *cft) |
3244 | { |
3245 | return clone_children(cgrp); |
3246 | } |
3247 | |
3248 | static int cgroup_clone_children_write(struct cgroup *cgrp, |
3249 | struct cftype *cft, |
3250 | u64 val) |
3251 | { |
3252 | if (val) |
3253 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); |
3254 | else |
3255 | clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); |
3256 | return 0; |
3257 | } |
3258 | |
3259 | /* |
3260 | * for the common functions, 'private' gives the type of file |
3261 | */ |
3262 | /* for hysterical raisins, we can't put this on the older files */ |
3263 | #define CGROUP_FILE_GENERIC_PREFIX "cgroup." |
3264 | static struct cftype files[] = { |
3265 | { |
3266 | .name = "tasks", |
3267 | .open = cgroup_tasks_open, |
3268 | .write_u64 = cgroup_tasks_write, |
3269 | .release = cgroup_pidlist_release, |
3270 | .mode = S_IRUGO | S_IWUSR, |
3271 | }, |
3272 | { |
3273 | .name = CGROUP_FILE_GENERIC_PREFIX "procs", |
3274 | .open = cgroup_procs_open, |
3275 | /* .write_u64 = cgroup_procs_write, TODO */ |
3276 | .release = cgroup_pidlist_release, |
3277 | .mode = S_IRUGO, |
3278 | }, |
3279 | { |
3280 | .name = "notify_on_release", |
3281 | .read_u64 = cgroup_read_notify_on_release, |
3282 | .write_u64 = cgroup_write_notify_on_release, |
3283 | }, |
3284 | { |
3285 | .name = CGROUP_FILE_GENERIC_PREFIX "event_control", |
3286 | .write_string = cgroup_write_event_control, |
3287 | .mode = S_IWUGO, |
3288 | }, |
3289 | { |
3290 | .name = "cgroup.clone_children", |
3291 | .read_u64 = cgroup_clone_children_read, |
3292 | .write_u64 = cgroup_clone_children_write, |
3293 | }, |
3294 | }; |
3295 | |
3296 | static struct cftype cft_release_agent = { |
3297 | .name = "release_agent", |
3298 | .read_seq_string = cgroup_release_agent_show, |
3299 | .write_string = cgroup_release_agent_write, |
3300 | .max_write_len = PATH_MAX, |
3301 | }; |
3302 | |
3303 | static int cgroup_populate_dir(struct cgroup *cgrp) |
3304 | { |
3305 | int err; |
3306 | struct cgroup_subsys *ss; |
3307 | |
3308 | /* First clear out any existing files */ |
3309 | cgroup_clear_directory(cgrp->dentry); |
3310 | |
3311 | err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files)); |
3312 | if (err < 0) |
3313 | return err; |
3314 | |
3315 | if (cgrp == cgrp->top_cgroup) { |
3316 | if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0) |
3317 | return err; |
3318 | } |
3319 | |
3320 | for_each_subsys(cgrp->root, ss) { |
3321 | if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) |
3322 | return err; |
3323 | } |
3324 | /* This cgroup is ready now */ |
3325 | for_each_subsys(cgrp->root, ss) { |
3326 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
3327 | /* |
3328 | * Update id->css pointer and make this css visible from |
3329 | * CSS ID functions. This pointer will be dereferened |
3330 | * from RCU-read-side without locks. |
3331 | */ |
3332 | if (css->id) |
3333 | rcu_assign_pointer(css->id->css, css); |
3334 | } |
3335 | |
3336 | return 0; |
3337 | } |
3338 | |
3339 | static void init_cgroup_css(struct cgroup_subsys_state *css, |
3340 | struct cgroup_subsys *ss, |
3341 | struct cgroup *cgrp) |
3342 | { |
3343 | css->cgroup = cgrp; |
3344 | atomic_set(&css->refcnt, 1); |
3345 | css->flags = 0; |
3346 | css->id = NULL; |
3347 | if (cgrp == dummytop) |
3348 | set_bit(CSS_ROOT, &css->flags); |
3349 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
3350 | cgrp->subsys[ss->subsys_id] = css; |
3351 | } |
3352 | |
3353 | static void cgroup_lock_hierarchy(struct cgroupfs_root *root) |
3354 | { |
3355 | /* We need to take each hierarchy_mutex in a consistent order */ |
3356 | int i; |
3357 | |
3358 | /* |
3359 | * No worry about a race with rebind_subsystems that might mess up the |
3360 | * locking order, since both parties are under cgroup_mutex. |
3361 | */ |
3362 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3363 | struct cgroup_subsys *ss = subsys[i]; |
3364 | if (ss == NULL) |
3365 | continue; |
3366 | if (ss->root == root) |
3367 | mutex_lock(&ss->hierarchy_mutex); |
3368 | } |
3369 | } |
3370 | |
3371 | static void cgroup_unlock_hierarchy(struct cgroupfs_root *root) |
3372 | { |
3373 | int i; |
3374 | |
3375 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3376 | struct cgroup_subsys *ss = subsys[i]; |
3377 | if (ss == NULL) |
3378 | continue; |
3379 | if (ss->root == root) |
3380 | mutex_unlock(&ss->hierarchy_mutex); |
3381 | } |
3382 | } |
3383 | |
3384 | /* |
3385 | * cgroup_create - create a cgroup |
3386 | * @parent: cgroup that will be parent of the new cgroup |
3387 | * @dentry: dentry of the new cgroup |
3388 | * @mode: mode to set on new inode |
3389 | * |
3390 | * Must be called with the mutex on the parent inode held |
3391 | */ |
3392 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
3393 | mode_t mode) |
3394 | { |
3395 | struct cgroup *cgrp; |
3396 | struct cgroupfs_root *root = parent->root; |
3397 | int err = 0; |
3398 | struct cgroup_subsys *ss; |
3399 | struct super_block *sb = root->sb; |
3400 | |
3401 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
3402 | if (!cgrp) |
3403 | return -ENOMEM; |
3404 | |
3405 | /* Grab a reference on the superblock so the hierarchy doesn't |
3406 | * get deleted on unmount if there are child cgroups. This |
3407 | * can be done outside cgroup_mutex, since the sb can't |
3408 | * disappear while someone has an open control file on the |
3409 | * fs */ |
3410 | atomic_inc(&sb->s_active); |
3411 | |
3412 | mutex_lock(&cgroup_mutex); |
3413 | |
3414 | init_cgroup_housekeeping(cgrp); |
3415 | |
3416 | cgrp->parent = parent; |
3417 | cgrp->root = parent->root; |
3418 | cgrp->top_cgroup = parent->top_cgroup; |
3419 | |
3420 | if (notify_on_release(parent)) |
3421 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
3422 | |
3423 | if (clone_children(parent)) |
3424 | set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); |
3425 | |
3426 | for_each_subsys(root, ss) { |
3427 | struct cgroup_subsys_state *css = ss->create(ss, cgrp); |
3428 | |
3429 | if (IS_ERR(css)) { |
3430 | err = PTR_ERR(css); |
3431 | goto err_destroy; |
3432 | } |
3433 | init_cgroup_css(css, ss, cgrp); |
3434 | if (ss->use_id) { |
3435 | err = alloc_css_id(ss, parent, cgrp); |
3436 | if (err) |
3437 | goto err_destroy; |
3438 | } |
3439 | /* At error, ->destroy() callback has to free assigned ID. */ |
3440 | if (clone_children(parent) && ss->post_clone) |
3441 | ss->post_clone(ss, cgrp); |
3442 | } |
3443 | |
3444 | cgroup_lock_hierarchy(root); |
3445 | list_add(&cgrp->sibling, &cgrp->parent->children); |
3446 | cgroup_unlock_hierarchy(root); |
3447 | root->number_of_cgroups++; |
3448 | |
3449 | err = cgroup_create_dir(cgrp, dentry, mode); |
3450 | if (err < 0) |
3451 | goto err_remove; |
3452 | |
3453 | /* The cgroup directory was pre-locked for us */ |
3454 | BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); |
3455 | |
3456 | err = cgroup_populate_dir(cgrp); |
3457 | /* If err < 0, we have a half-filled directory - oh well ;) */ |
3458 | |
3459 | mutex_unlock(&cgroup_mutex); |
3460 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
3461 | |
3462 | return 0; |
3463 | |
3464 | err_remove: |
3465 | |
3466 | cgroup_lock_hierarchy(root); |
3467 | list_del(&cgrp->sibling); |
3468 | cgroup_unlock_hierarchy(root); |
3469 | root->number_of_cgroups--; |
3470 | |
3471 | err_destroy: |
3472 | |
3473 | for_each_subsys(root, ss) { |
3474 | if (cgrp->subsys[ss->subsys_id]) |
3475 | ss->destroy(ss, cgrp); |
3476 | } |
3477 | |
3478 | mutex_unlock(&cgroup_mutex); |
3479 | |
3480 | /* Release the reference count that we took on the superblock */ |
3481 | deactivate_super(sb); |
3482 | |
3483 | kfree(cgrp); |
3484 | return err; |
3485 | } |
3486 | |
3487 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
3488 | { |
3489 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; |
3490 | |
3491 | /* the vfs holds inode->i_mutex already */ |
3492 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); |
3493 | } |
3494 | |
3495 | static int cgroup_has_css_refs(struct cgroup *cgrp) |
3496 | { |
3497 | /* Check the reference count on each subsystem. Since we |
3498 | * already established that there are no tasks in the |
3499 | * cgroup, if the css refcount is also 1, then there should |
3500 | * be no outstanding references, so the subsystem is safe to |
3501 | * destroy. We scan across all subsystems rather than using |
3502 | * the per-hierarchy linked list of mounted subsystems since |
3503 | * we can be called via check_for_release() with no |
3504 | * synchronization other than RCU, and the subsystem linked |
3505 | * list isn't RCU-safe */ |
3506 | int i; |
3507 | /* |
3508 | * We won't need to lock the subsys array, because the subsystems |
3509 | * we're concerned about aren't going anywhere since our cgroup root |
3510 | * has a reference on them. |
3511 | */ |
3512 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
3513 | struct cgroup_subsys *ss = subsys[i]; |
3514 | struct cgroup_subsys_state *css; |
3515 | /* Skip subsystems not present or not in this hierarchy */ |
3516 | if (ss == NULL || ss->root != cgrp->root) |
3517 | continue; |
3518 | css = cgrp->subsys[ss->subsys_id]; |
3519 | /* When called from check_for_release() it's possible |
3520 | * that by this point the cgroup has been removed |
3521 | * and the css deleted. But a false-positive doesn't |
3522 | * matter, since it can only happen if the cgroup |
3523 | * has been deleted and hence no longer needs the |
3524 | * release agent to be called anyway. */ |
3525 | if (css && (atomic_read(&css->refcnt) > 1)) |
3526 | return 1; |
3527 | } |
3528 | return 0; |
3529 | } |
3530 | |
3531 | /* |
3532 | * Atomically mark all (or else none) of the cgroup's CSS objects as |
3533 | * CSS_REMOVED. Return true on success, or false if the cgroup has |
3534 | * busy subsystems. Call with cgroup_mutex held |
3535 | */ |
3536 | |
3537 | static int cgroup_clear_css_refs(struct cgroup *cgrp) |
3538 | { |
3539 | struct cgroup_subsys *ss; |
3540 | unsigned long flags; |
3541 | bool failed = false; |
3542 | local_irq_save(flags); |
3543 | for_each_subsys(cgrp->root, ss) { |
3544 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
3545 | int refcnt; |
3546 | while (1) { |
3547 | /* We can only remove a CSS with a refcnt==1 */ |
3548 | refcnt = atomic_read(&css->refcnt); |
3549 | if (refcnt > 1) { |
3550 | failed = true; |
3551 | goto done; |
3552 | } |
3553 | BUG_ON(!refcnt); |
3554 | /* |
3555 | * Drop the refcnt to 0 while we check other |
3556 | * subsystems. This will cause any racing |
3557 | * css_tryget() to spin until we set the |
3558 | * CSS_REMOVED bits or abort |
3559 | */ |
3560 | if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt) |
3561 | break; |
3562 | cpu_relax(); |
3563 | } |
3564 | } |
3565 | done: |
3566 | for_each_subsys(cgrp->root, ss) { |
3567 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
3568 | if (failed) { |
3569 | /* |
3570 | * Restore old refcnt if we previously managed |
3571 | * to clear it from 1 to 0 |
3572 | */ |
3573 | if (!atomic_read(&css->refcnt)) |
3574 | atomic_set(&css->refcnt, 1); |
3575 | } else { |
3576 | /* Commit the fact that the CSS is removed */ |
3577 | set_bit(CSS_REMOVED, &css->flags); |
3578 | } |
3579 | } |
3580 | local_irq_restore(flags); |
3581 | return !failed; |
3582 | } |
3583 | |
3584 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
3585 | { |
3586 | struct cgroup *cgrp = dentry->d_fsdata; |
3587 | struct dentry *d; |
3588 | struct cgroup *parent; |
3589 | DEFINE_WAIT(wait); |
3590 | struct cgroup_event *event, *tmp; |
3591 | int ret; |
3592 | |
3593 | /* the vfs holds both inode->i_mutex already */ |
3594 | again: |
3595 | mutex_lock(&cgroup_mutex); |
3596 | if (atomic_read(&cgrp->count) != 0) { |
3597 | mutex_unlock(&cgroup_mutex); |
3598 | return -EBUSY; |
3599 | } |
3600 | if (!list_empty(&cgrp->children)) { |
3601 | mutex_unlock(&cgroup_mutex); |
3602 | return -EBUSY; |
3603 | } |
3604 | mutex_unlock(&cgroup_mutex); |
3605 | |
3606 | /* |
3607 | * In general, subsystem has no css->refcnt after pre_destroy(). But |
3608 | * in racy cases, subsystem may have to get css->refcnt after |
3609 | * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes |
3610 | * make rmdir return -EBUSY too often. To avoid that, we use waitqueue |
3611 | * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir |
3612 | * and subsystem's reference count handling. Please see css_get/put |
3613 | * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation. |
3614 | */ |
3615 | set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
3616 | |
3617 | /* |
3618 | * Call pre_destroy handlers of subsys. Notify subsystems |
3619 | * that rmdir() request comes. |
3620 | */ |
3621 | ret = cgroup_call_pre_destroy(cgrp); |
3622 | if (ret) { |
3623 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
3624 | return ret; |
3625 | } |
3626 | |
3627 | mutex_lock(&cgroup_mutex); |
3628 | parent = cgrp->parent; |
3629 | if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { |
3630 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
3631 | mutex_unlock(&cgroup_mutex); |
3632 | return -EBUSY; |
3633 | } |
3634 | prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE); |
3635 | if (!cgroup_clear_css_refs(cgrp)) { |
3636 | mutex_unlock(&cgroup_mutex); |
3637 | /* |
3638 | * Because someone may call cgroup_wakeup_rmdir_waiter() before |
3639 | * prepare_to_wait(), we need to check this flag. |
3640 | */ |
3641 | if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)) |
3642 | schedule(); |
3643 | finish_wait(&cgroup_rmdir_waitq, &wait); |
3644 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
3645 | if (signal_pending(current)) |
3646 | return -EINTR; |
3647 | goto again; |
3648 | } |
3649 | /* NO css_tryget() can success after here. */ |
3650 | finish_wait(&cgroup_rmdir_waitq, &wait); |
3651 | clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); |
3652 | |
3653 | spin_lock(&release_list_lock); |
3654 | set_bit(CGRP_REMOVED, &cgrp->flags); |
3655 | if (!list_empty(&cgrp->release_list)) |
3656 | list_del_init(&cgrp->release_list); |
3657 | spin_unlock(&release_list_lock); |
3658 | |
3659 | cgroup_lock_hierarchy(cgrp->root); |
3660 | /* delete this cgroup from parent->children */ |
3661 | list_del_init(&cgrp->sibling); |
3662 | cgroup_unlock_hierarchy(cgrp->root); |
3663 | |
3664 | d = dget(cgrp->dentry); |
3665 | |
3666 | cgroup_d_remove_dir(d); |
3667 | dput(d); |
3668 | |
3669 | set_bit(CGRP_RELEASABLE, &parent->flags); |
3670 | check_for_release(parent); |
3671 | |
3672 | /* |
3673 | * Unregister events and notify userspace. |
3674 | * Notify userspace about cgroup removing only after rmdir of cgroup |
3675 | * directory to avoid race between userspace and kernelspace |
3676 | */ |
3677 | spin_lock(&cgrp->event_list_lock); |
3678 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { |
3679 | list_del(&event->list); |
3680 | remove_wait_queue(event->wqh, &event->wait); |
3681 | eventfd_signal(event->eventfd, 1); |
3682 | schedule_work(&event->remove); |
3683 | } |
3684 | spin_unlock(&cgrp->event_list_lock); |
3685 | |
3686 | mutex_unlock(&cgroup_mutex); |
3687 | return 0; |
3688 | } |
3689 | |
3690 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
3691 | { |
3692 | struct cgroup_subsys_state *css; |
3693 | |
3694 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); |
3695 | |
3696 | /* Create the top cgroup state for this subsystem */ |
3697 | list_add(&ss->sibling, &rootnode.subsys_list); |
3698 | ss->root = &rootnode; |
3699 | css = ss->create(ss, dummytop); |
3700 | /* We don't handle early failures gracefully */ |
3701 | BUG_ON(IS_ERR(css)); |
3702 | init_cgroup_css(css, ss, dummytop); |
3703 | |
3704 | /* Update the init_css_set to contain a subsys |
3705 | * pointer to this state - since the subsystem is |
3706 | * newly registered, all tasks and hence the |
3707 | * init_css_set is in the subsystem's top cgroup. */ |
3708 | init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id]; |
3709 | |
3710 | need_forkexit_callback |= ss->fork || ss->exit; |
3711 | |
3712 | /* At system boot, before all subsystems have been |
3713 | * registered, no tasks have been forked, so we don't |
3714 | * need to invoke fork callbacks here. */ |
3715 | BUG_ON(!list_empty(&init_task.tasks)); |
3716 | |
3717 | mutex_init(&ss->hierarchy_mutex); |
3718 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); |
3719 | ss->active = 1; |
3720 | |
3721 | /* this function shouldn't be used with modular subsystems, since they |
3722 | * need to register a subsys_id, among other things */ |
3723 | BUG_ON(ss->module); |
3724 | } |
3725 | |
3726 | /** |
3727 | * cgroup_load_subsys: load and register a modular subsystem at runtime |
3728 | * @ss: the subsystem to load |
3729 | * |
3730 | * This function should be called in a modular subsystem's initcall. If the |
3731 | * subsystem is built as a module, it will be assigned a new subsys_id and set |
3732 | * up for use. If the subsystem is built-in anyway, work is delegated to the |
3733 | * simpler cgroup_init_subsys. |
3734 | */ |
3735 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) |
3736 | { |
3737 | int i; |
3738 | struct cgroup_subsys_state *css; |
3739 | |
3740 | /* check name and function validity */ |
3741 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || |
3742 | ss->create == NULL || ss->destroy == NULL) |
3743 | return -EINVAL; |
3744 | |
3745 | /* |
3746 | * we don't support callbacks in modular subsystems. this check is |
3747 | * before the ss->module check for consistency; a subsystem that could |
3748 | * be a module should still have no callbacks even if the user isn't |
3749 | * compiling it as one. |
3750 | */ |
3751 | if (ss->fork || ss->exit) |
3752 | return -EINVAL; |
3753 | |
3754 | /* |
3755 | * an optionally modular subsystem is built-in: we want to do nothing, |
3756 | * since cgroup_init_subsys will have already taken care of it. |
3757 | */ |
3758 | if (ss->module == NULL) { |
3759 | /* a few sanity checks */ |
3760 | BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); |
3761 | BUG_ON(subsys[ss->subsys_id] != ss); |
3762 | return 0; |
3763 | } |
3764 | |
3765 | /* |
3766 | * need to register a subsys id before anything else - for example, |
3767 | * init_cgroup_css needs it. |
3768 | */ |
3769 | mutex_lock(&cgroup_mutex); |
3770 | /* find the first empty slot in the array */ |
3771 | for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { |
3772 | if (subsys[i] == NULL) |
3773 | break; |
3774 | } |
3775 | if (i == CGROUP_SUBSYS_COUNT) { |
3776 | /* maximum number of subsystems already registered! */ |
3777 | mutex_unlock(&cgroup_mutex); |
3778 | return -EBUSY; |
3779 | } |
3780 | /* assign ourselves the subsys_id */ |
3781 | ss->subsys_id = i; |
3782 | subsys[i] = ss; |
3783 | |
3784 | /* |
3785 | * no ss->create seems to need anything important in the ss struct, so |
3786 | * this can happen first (i.e. before the rootnode attachment). |
3787 | */ |
3788 | css = ss->create(ss, dummytop); |
3789 | if (IS_ERR(css)) { |
3790 | /* failure case - need to deassign the subsys[] slot. */ |
3791 | subsys[i] = NULL; |
3792 | mutex_unlock(&cgroup_mutex); |
3793 | return PTR_ERR(css); |
3794 | } |
3795 | |
3796 | list_add(&ss->sibling, &rootnode.subsys_list); |
3797 | ss->root = &rootnode; |
3798 | |
3799 | /* our new subsystem will be attached to the dummy hierarchy. */ |
3800 | init_cgroup_css(css, ss, dummytop); |
3801 | /* init_idr must be after init_cgroup_css because it sets css->id. */ |
3802 | if (ss->use_id) { |
3803 | int ret = cgroup_init_idr(ss, css); |
3804 | if (ret) { |
3805 | dummytop->subsys[ss->subsys_id] = NULL; |
3806 | ss->destroy(ss, dummytop); |
3807 | subsys[i] = NULL; |
3808 | mutex_unlock(&cgroup_mutex); |
3809 | return ret; |
3810 | } |
3811 | } |
3812 | |
3813 | /* |
3814 | * Now we need to entangle the css into the existing css_sets. unlike |
3815 | * in cgroup_init_subsys, there are now multiple css_sets, so each one |
3816 | * will need a new pointer to it; done by iterating the css_set_table. |
3817 | * furthermore, modifying the existing css_sets will corrupt the hash |
3818 | * table state, so each changed css_set will need its hash recomputed. |
3819 | * this is all done under the css_set_lock. |
3820 | */ |
3821 | write_lock(&css_set_lock); |
3822 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { |
3823 | struct css_set *cg; |
3824 | struct hlist_node *node, *tmp; |
3825 | struct hlist_head *bucket = &css_set_table[i], *new_bucket; |
3826 | |
3827 | hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { |
3828 | /* skip entries that we already rehashed */ |
3829 | if (cg->subsys[ss->subsys_id]) |
3830 | continue; |
3831 | /* remove existing entry */ |
3832 | hlist_del(&cg->hlist); |
3833 | /* set new value */ |
3834 | cg->subsys[ss->subsys_id] = css; |
3835 | /* recompute hash and restore entry */ |
3836 | new_bucket = css_set_hash(cg->subsys); |
3837 | hlist_add_head(&cg->hlist, new_bucket); |
3838 | } |
3839 | } |
3840 | write_unlock(&css_set_lock); |
3841 | |
3842 | mutex_init(&ss->hierarchy_mutex); |
3843 | lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); |
3844 | ss->active = 1; |
3845 | |
3846 | /* success! */ |
3847 | mutex_unlock(&cgroup_mutex); |
3848 | return 0; |
3849 | } |
3850 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
3851 | |
3852 | /** |
3853 | * cgroup_unload_subsys: unload a modular subsystem |
3854 | * @ss: the subsystem to unload |
3855 | * |
3856 | * This function should be called in a modular subsystem's exitcall. When this |
3857 | * function is invoked, the refcount on the subsystem's module will be 0, so |
3858 | * the subsystem will not be attached to any hierarchy. |
3859 | */ |
3860 | void cgroup_unload_subsys(struct cgroup_subsys *ss) |
3861 | { |
3862 | struct cg_cgroup_link *link; |
3863 | struct hlist_head *hhead; |
3864 | |
3865 | BUG_ON(ss->module == NULL); |
3866 | |
3867 | /* |
3868 | * we shouldn't be called if the subsystem is in use, and the use of |
3869 | * try_module_get in parse_cgroupfs_options should ensure that it |
3870 | * doesn't start being used while we're killing it off. |
3871 | */ |
3872 | BUG_ON(ss->root != &rootnode); |
3873 | |
3874 | mutex_lock(&cgroup_mutex); |
3875 | /* deassign the subsys_id */ |
3876 | BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT); |
3877 | subsys[ss->subsys_id] = NULL; |
3878 | |
3879 | /* remove subsystem from rootnode's list of subsystems */ |
3880 | list_del_init(&ss->sibling); |
3881 | |
3882 | /* |
3883 | * disentangle the css from all css_sets attached to the dummytop. as |
3884 | * in loading, we need to pay our respects to the hashtable gods. |
3885 | */ |
3886 | write_lock(&css_set_lock); |
3887 | list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { |
3888 | struct css_set *cg = link->cg; |
3889 | |
3890 | hlist_del(&cg->hlist); |
3891 | BUG_ON(!cg->subsys[ss->subsys_id]); |
3892 | cg->subsys[ss->subsys_id] = NULL; |
3893 | hhead = css_set_hash(cg->subsys); |
3894 | hlist_add_head(&cg->hlist, hhead); |
3895 | } |
3896 | write_unlock(&css_set_lock); |
3897 | |
3898 | /* |
3899 | * remove subsystem's css from the dummytop and free it - need to free |
3900 | * before marking as null because ss->destroy needs the cgrp->subsys |
3901 | * pointer to find their state. note that this also takes care of |
3902 | * freeing the css_id. |
3903 | */ |
3904 | ss->destroy(ss, dummytop); |
3905 | dummytop->subsys[ss->subsys_id] = NULL; |
3906 | |
3907 | mutex_unlock(&cgroup_mutex); |
3908 | } |
3909 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); |
3910 | |
3911 | /** |
3912 | * cgroup_init_early - cgroup initialization at system boot |
3913 | * |
3914 | * Initialize cgroups at system boot, and initialize any |
3915 | * subsystems that request early init. |
3916 | */ |
3917 | int __init cgroup_init_early(void) |
3918 | { |
3919 | int i; |
3920 | atomic_set(&init_css_set.refcount, 1); |
3921 | INIT_LIST_HEAD(&init_css_set.cg_links); |
3922 | INIT_LIST_HEAD(&init_css_set.tasks); |
3923 | INIT_HLIST_NODE(&init_css_set.hlist); |
3924 | css_set_count = 1; |
3925 | init_cgroup_root(&rootnode); |
3926 | root_count = 1; |
3927 | init_task.cgroups = &init_css_set; |
3928 | |
3929 | init_css_set_link.cg = &init_css_set; |
3930 | init_css_set_link.cgrp = dummytop; |
3931 | list_add(&init_css_set_link.cgrp_link_list, |
3932 | &rootnode.top_cgroup.css_sets); |
3933 | list_add(&init_css_set_link.cg_link_list, |
3934 | &init_css_set.cg_links); |
3935 | |
3936 | for (i = 0; i < CSS_SET_TABLE_SIZE; i++) |
3937 | INIT_HLIST_HEAD(&css_set_table[i]); |
3938 | |
3939 | /* at bootup time, we don't worry about modular subsystems */ |
3940 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { |
3941 | struct cgroup_subsys *ss = subsys[i]; |
3942 | |
3943 | BUG_ON(!ss->name); |
3944 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); |
3945 | BUG_ON(!ss->create); |
3946 | BUG_ON(!ss->destroy); |
3947 | if (ss->subsys_id != i) { |
3948 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
3949 | ss->name, ss->subsys_id); |
3950 | BUG(); |
3951 | } |
3952 | |
3953 | if (ss->early_init) |
3954 | cgroup_init_subsys(ss); |
3955 | } |
3956 | return 0; |
3957 | } |
3958 | |
3959 | /** |
3960 | * cgroup_init - cgroup initialization |
3961 | * |
3962 | * Register cgroup filesystem and /proc file, and initialize |
3963 | * any subsystems that didn't request early init. |
3964 | */ |
3965 | int __init cgroup_init(void) |
3966 | { |
3967 | int err; |
3968 | int i; |
3969 | struct hlist_head *hhead; |
3970 | |
3971 | err = bdi_init(&cgroup_backing_dev_info); |
3972 | if (err) |
3973 | return err; |
3974 | |
3975 | /* at bootup time, we don't worry about modular subsystems */ |
3976 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { |
3977 | struct cgroup_subsys *ss = subsys[i]; |
3978 | if (!ss->early_init) |
3979 | cgroup_init_subsys(ss); |
3980 | if (ss->use_id) |
3981 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
3982 | } |
3983 | |
3984 | /* Add init_css_set to the hash table */ |
3985 | hhead = css_set_hash(init_css_set.subsys); |
3986 | hlist_add_head(&init_css_set.hlist, hhead); |
3987 | BUG_ON(!init_root_id(&rootnode)); |
3988 | |
3989 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
3990 | if (!cgroup_kobj) { |
3991 | err = -ENOMEM; |
3992 | goto out; |
3993 | } |
3994 | |
3995 | err = register_filesystem(&cgroup_fs_type); |
3996 | if (err < 0) { |
3997 | kobject_put(cgroup_kobj); |
3998 | goto out; |
3999 | } |
4000 | |
4001 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
4002 | |
4003 | out: |
4004 | if (err) |
4005 | bdi_destroy(&cgroup_backing_dev_info); |
4006 | |
4007 | return err; |
4008 | } |
4009 | |
4010 | /* |
4011 | * proc_cgroup_show() |
4012 | * - Print task's cgroup paths into seq_file, one line for each hierarchy |
4013 | * - Used for /proc/<pid>/cgroup. |
4014 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it |
4015 | * doesn't really matter if tsk->cgroup changes after we read it, |
4016 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
4017 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
4018 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks |
4019 | * cgroup to top_cgroup. |
4020 | */ |
4021 | |
4022 | /* TODO: Use a proper seq_file iterator */ |
4023 | static int proc_cgroup_show(struct seq_file *m, void *v) |
4024 | { |
4025 | struct pid *pid; |
4026 | struct task_struct *tsk; |
4027 | char *buf; |
4028 | int retval; |
4029 | struct cgroupfs_root *root; |
4030 | |
4031 | retval = -ENOMEM; |
4032 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
4033 | if (!buf) |
4034 | goto out; |
4035 | |
4036 | retval = -ESRCH; |
4037 | pid = m->private; |
4038 | tsk = get_pid_task(pid, PIDTYPE_PID); |
4039 | if (!tsk) |
4040 | goto out_free; |
4041 | |
4042 | retval = 0; |
4043 | |
4044 | mutex_lock(&cgroup_mutex); |
4045 | |
4046 | for_each_active_root(root) { |
4047 | struct cgroup_subsys *ss; |
4048 | struct cgroup *cgrp; |
4049 | int count = 0; |
4050 | |
4051 | seq_printf(m, "%d:", root->hierarchy_id); |
4052 | for_each_subsys(root, ss) |
4053 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); |
4054 | if (strlen(root->name)) |
4055 | seq_printf(m, "%sname=%s", count ? "," : "", |
4056 | root->name); |
4057 | seq_putc(m, ':'); |
4058 | cgrp = task_cgroup_from_root(tsk, root); |
4059 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
4060 | if (retval < 0) |
4061 | goto out_unlock; |
4062 | seq_puts(m, buf); |
4063 | seq_putc(m, '\n'); |
4064 | } |
4065 | |
4066 | out_unlock: |
4067 | mutex_unlock(&cgroup_mutex); |
4068 | put_task_struct(tsk); |
4069 | out_free: |
4070 | kfree(buf); |
4071 | out: |
4072 | return retval; |
4073 | } |
4074 | |
4075 | static int cgroup_open(struct inode *inode, struct file *file) |
4076 | { |
4077 | struct pid *pid = PROC_I(inode)->pid; |
4078 | return single_open(file, proc_cgroup_show, pid); |
4079 | } |
4080 | |
4081 | const struct file_operations proc_cgroup_operations = { |
4082 | .open = cgroup_open, |
4083 | .read = seq_read, |
4084 | .llseek = seq_lseek, |
4085 | .release = single_release, |
4086 | }; |
4087 | |
4088 | /* Display information about each subsystem and each hierarchy */ |
4089 | static int proc_cgroupstats_show(struct seq_file *m, void *v) |
4090 | { |
4091 | int i; |
4092 | |
4093 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
4094 | /* |
4095 | * ideally we don't want subsystems moving around while we do this. |
4096 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of |
4097 | * subsys/hierarchy state. |
4098 | */ |
4099 | mutex_lock(&cgroup_mutex); |
4100 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
4101 | struct cgroup_subsys *ss = subsys[i]; |
4102 | if (ss == NULL) |
4103 | continue; |
4104 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4105 | ss->name, ss->root->hierarchy_id, |
4106 | ss->root->number_of_cgroups, !ss->disabled); |
4107 | } |
4108 | mutex_unlock(&cgroup_mutex); |
4109 | return 0; |
4110 | } |
4111 | |
4112 | static int cgroupstats_open(struct inode *inode, struct file *file) |
4113 | { |
4114 | return single_open(file, proc_cgroupstats_show, NULL); |
4115 | } |
4116 | |
4117 | static const struct file_operations proc_cgroupstats_operations = { |
4118 | .open = cgroupstats_open, |
4119 | .read = seq_read, |
4120 | .llseek = seq_lseek, |
4121 | .release = single_release, |
4122 | }; |
4123 | |
4124 | /** |
4125 | * cgroup_fork - attach newly forked task to its parents cgroup. |
4126 | * @child: pointer to task_struct of forking parent process. |
4127 | * |
4128 | * Description: A task inherits its parent's cgroup at fork(). |
4129 | * |
4130 | * A pointer to the shared css_set was automatically copied in |
4131 | * fork.c by dup_task_struct(). However, we ignore that copy, since |
4132 | * it was not made under the protection of RCU or cgroup_mutex, so |
4133 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might |
4134 | * have already changed current->cgroups, allowing the previously |
4135 | * referenced cgroup group to be removed and freed. |
4136 | * |
4137 | * At the point that cgroup_fork() is called, 'current' is the parent |
4138 | * task, and the passed argument 'child' points to the child task. |
4139 | */ |
4140 | void cgroup_fork(struct task_struct *child) |
4141 | { |
4142 | task_lock(current); |
4143 | child->cgroups = current->cgroups; |
4144 | get_css_set(child->cgroups); |
4145 | task_unlock(current); |
4146 | INIT_LIST_HEAD(&child->cg_list); |
4147 | } |
4148 | |
4149 | /** |
4150 | * cgroup_fork_callbacks - run fork callbacks |
4151 | * @child: the new task |
4152 | * |
4153 | * Called on a new task very soon before adding it to the |
4154 | * tasklist. No need to take any locks since no-one can |
4155 | * be operating on this task. |
4156 | */ |
4157 | void cgroup_fork_callbacks(struct task_struct *child) |
4158 | { |
4159 | if (need_forkexit_callback) { |
4160 | int i; |
4161 | /* |
4162 | * forkexit callbacks are only supported for builtin |
4163 | * subsystems, and the builtin section of the subsys array is |
4164 | * immutable, so we don't need to lock the subsys array here. |
4165 | */ |
4166 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { |
4167 | struct cgroup_subsys *ss = subsys[i]; |
4168 | if (ss->fork) |
4169 | ss->fork(ss, child); |
4170 | } |
4171 | } |
4172 | } |
4173 | |
4174 | /** |
4175 | * cgroup_post_fork - called on a new task after adding it to the task list |
4176 | * @child: the task in question |
4177 | * |
4178 | * Adds the task to the list running through its css_set if necessary. |
4179 | * Has to be after the task is visible on the task list in case we race |
4180 | * with the first call to cgroup_iter_start() - to guarantee that the |
4181 | * new task ends up on its list. |
4182 | */ |
4183 | void cgroup_post_fork(struct task_struct *child) |
4184 | { |
4185 | if (use_task_css_set_links) { |
4186 | write_lock(&css_set_lock); |
4187 | task_lock(child); |
4188 | if (list_empty(&child->cg_list)) |
4189 | list_add(&child->cg_list, &child->cgroups->tasks); |
4190 | task_unlock(child); |
4191 | write_unlock(&css_set_lock); |
4192 | } |
4193 | } |
4194 | /** |
4195 | * cgroup_exit - detach cgroup from exiting task |
4196 | * @tsk: pointer to task_struct of exiting process |
4197 | * @run_callback: run exit callbacks? |
4198 | * |
4199 | * Description: Detach cgroup from @tsk and release it. |
4200 | * |
4201 | * Note that cgroups marked notify_on_release force every task in |
4202 | * them to take the global cgroup_mutex mutex when exiting. |
4203 | * This could impact scaling on very large systems. Be reluctant to |
4204 | * use notify_on_release cgroups where very high task exit scaling |
4205 | * is required on large systems. |
4206 | * |
4207 | * the_top_cgroup_hack: |
4208 | * |
4209 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). |
4210 | * |
4211 | * We call cgroup_exit() while the task is still competent to |
4212 | * handle notify_on_release(), then leave the task attached to the |
4213 | * root cgroup in each hierarchy for the remainder of its exit. |
4214 | * |
4215 | * To do this properly, we would increment the reference count on |
4216 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() |
4217 | * code we would add a second cgroup function call, to drop that |
4218 | * reference. This would just create an unnecessary hot spot on |
4219 | * the top_cgroup reference count, to no avail. |
4220 | * |
4221 | * Normally, holding a reference to a cgroup without bumping its |
4222 | * count is unsafe. The cgroup could go away, or someone could |
4223 | * attach us to a different cgroup, decrementing the count on |
4224 | * the first cgroup that we never incremented. But in this case, |
4225 | * top_cgroup isn't going away, and either task has PF_EXITING set, |
4226 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
4227 | * fork, never visible to cgroup_attach_task. |
4228 | */ |
4229 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) |
4230 | { |
4231 | struct css_set *cg; |
4232 | int i; |
4233 | |
4234 | /* |
4235 | * Unlink from the css_set task list if necessary. |
4236 | * Optimistically check cg_list before taking |
4237 | * css_set_lock |
4238 | */ |
4239 | if (!list_empty(&tsk->cg_list)) { |
4240 | write_lock(&css_set_lock); |
4241 | if (!list_empty(&tsk->cg_list)) |
4242 | list_del_init(&tsk->cg_list); |
4243 | write_unlock(&css_set_lock); |
4244 | } |
4245 | |
4246 | /* Reassign the task to the init_css_set. */ |
4247 | task_lock(tsk); |
4248 | cg = tsk->cgroups; |
4249 | tsk->cgroups = &init_css_set; |
4250 | |
4251 | if (run_callbacks && need_forkexit_callback) { |
4252 | /* |
4253 | * modular subsystems can't use callbacks, so no need to lock |
4254 | * the subsys array |
4255 | */ |
4256 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { |
4257 | struct cgroup_subsys *ss = subsys[i]; |
4258 | if (ss->exit) { |
4259 | struct cgroup *old_cgrp = |
4260 | rcu_dereference_raw(cg->subsys[i])->cgroup; |
4261 | struct cgroup *cgrp = task_cgroup(tsk, i); |
4262 | ss->exit(ss, cgrp, old_cgrp, tsk); |
4263 | } |
4264 | } |
4265 | } |
4266 | task_unlock(tsk); |
4267 | |
4268 | if (cg) |
4269 | put_css_set_taskexit(cg); |
4270 | } |
4271 | |
4272 | /** |
4273 | * cgroup_clone - clone the cgroup the given subsystem is attached to |
4274 | * @tsk: the task to be moved |
4275 | * @subsys: the given subsystem |
4276 | * @nodename: the name for the new cgroup |
4277 | * |
4278 | * Duplicate the current cgroup in the hierarchy that the given |
4279 | * subsystem is attached to, and move this task into the new |
4280 | * child. |
4281 | */ |
4282 | int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, |
4283 | char *nodename) |
4284 | { |
4285 | struct dentry *dentry; |
4286 | int ret = 0; |
4287 | struct cgroup *parent, *child; |
4288 | struct inode *inode; |
4289 | struct css_set *cg; |
4290 | struct cgroupfs_root *root; |
4291 | struct cgroup_subsys *ss; |
4292 | |
4293 | /* We shouldn't be called by an unregistered subsystem */ |
4294 | BUG_ON(!subsys->active); |
4295 | |
4296 | /* First figure out what hierarchy and cgroup we're dealing |
4297 | * with, and pin them so we can drop cgroup_mutex */ |
4298 | mutex_lock(&cgroup_mutex); |
4299 | again: |
4300 | root = subsys->root; |
4301 | if (root == &rootnode) { |
4302 | mutex_unlock(&cgroup_mutex); |
4303 | return 0; |
4304 | } |
4305 | |
4306 | /* Pin the hierarchy */ |
4307 | if (!atomic_inc_not_zero(&root->sb->s_active)) { |
4308 | /* We race with the final deactivate_super() */ |
4309 | mutex_unlock(&cgroup_mutex); |
4310 | return 0; |
4311 | } |
4312 | |
4313 | /* Keep the cgroup alive */ |
4314 | task_lock(tsk); |
4315 | parent = task_cgroup(tsk, subsys->subsys_id); |
4316 | cg = tsk->cgroups; |
4317 | get_css_set(cg); |
4318 | task_unlock(tsk); |
4319 | |
4320 | mutex_unlock(&cgroup_mutex); |
4321 | |
4322 | /* Now do the VFS work to create a cgroup */ |
4323 | inode = parent->dentry->d_inode; |
4324 | |
4325 | /* Hold the parent directory mutex across this operation to |
4326 | * stop anyone else deleting the new cgroup */ |
4327 | mutex_lock(&inode->i_mutex); |
4328 | dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename)); |
4329 | if (IS_ERR(dentry)) { |
4330 | printk(KERN_INFO |
4331 | "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename, |
4332 | PTR_ERR(dentry)); |
4333 | ret = PTR_ERR(dentry); |
4334 | goto out_release; |
4335 | } |
4336 | |
4337 | /* Create the cgroup directory, which also creates the cgroup */ |
4338 | ret = vfs_mkdir(inode, dentry, 0755); |
4339 | child = __d_cgrp(dentry); |
4340 | dput(dentry); |
4341 | if (ret) { |
4342 | printk(KERN_INFO |
4343 | "Failed to create cgroup %s: %d\n", nodename, |
4344 | ret); |
4345 | goto out_release; |
4346 | } |
4347 | |
4348 | /* The cgroup now exists. Retake cgroup_mutex and check |
4349 | * that we're still in the same state that we thought we |
4350 | * were. */ |
4351 | mutex_lock(&cgroup_mutex); |
4352 | if ((root != subsys->root) || |
4353 | (parent != task_cgroup(tsk, subsys->subsys_id))) { |
4354 | /* Aargh, we raced ... */ |
4355 | mutex_unlock(&inode->i_mutex); |
4356 | put_css_set(cg); |
4357 | |
4358 | deactivate_super(root->sb); |
4359 | /* The cgroup is still accessible in the VFS, but |
4360 | * we're not going to try to rmdir() it at this |
4361 | * point. */ |
4362 | printk(KERN_INFO |
4363 | "Race in cgroup_clone() - leaking cgroup %s\n", |
4364 | nodename); |
4365 | goto again; |
4366 | } |
4367 | |
4368 | /* do any required auto-setup */ |
4369 | for_each_subsys(root, ss) { |
4370 | if (ss->post_clone) |
4371 | ss->post_clone(ss, child); |
4372 | } |
4373 | |
4374 | /* All seems fine. Finish by moving the task into the new cgroup */ |
4375 | ret = cgroup_attach_task(child, tsk); |
4376 | mutex_unlock(&cgroup_mutex); |
4377 | |
4378 | out_release: |
4379 | mutex_unlock(&inode->i_mutex); |
4380 | |
4381 | mutex_lock(&cgroup_mutex); |
4382 | put_css_set(cg); |
4383 | mutex_unlock(&cgroup_mutex); |
4384 | deactivate_super(root->sb); |
4385 | return ret; |
4386 | } |
4387 | |
4388 | /** |
4389 | * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp |
4390 | * @cgrp: the cgroup in question |
4391 | * @task: the task in question |
4392 | * |
4393 | * See if @cgrp is a descendant of @task's cgroup in the appropriate |
4394 | * hierarchy. |
4395 | * |
4396 | * If we are sending in dummytop, then presumably we are creating |
4397 | * the top cgroup in the subsystem. |
4398 | * |
4399 | * Called only by the ns (nsproxy) cgroup. |
4400 | */ |
4401 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) |
4402 | { |
4403 | int ret; |
4404 | struct cgroup *target; |
4405 | |
4406 | if (cgrp == dummytop) |
4407 | return 1; |
4408 | |
4409 | target = task_cgroup_from_root(task, cgrp->root); |
4410 | while (cgrp != target && cgrp!= cgrp->top_cgroup) |
4411 | cgrp = cgrp->parent; |
4412 | ret = (cgrp == target); |
4413 | return ret; |
4414 | } |
4415 | |
4416 | static void check_for_release(struct cgroup *cgrp) |
4417 | { |
4418 | /* All of these checks rely on RCU to keep the cgroup |
4419 | * structure alive */ |
4420 | if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) |
4421 | && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { |
4422 | /* Control Group is currently removeable. If it's not |
4423 | * already queued for a userspace notification, queue |
4424 | * it now */ |
4425 | int need_schedule_work = 0; |
4426 | spin_lock(&release_list_lock); |
4427 | if (!cgroup_is_removed(cgrp) && |
4428 | list_empty(&cgrp->release_list)) { |
4429 | list_add(&cgrp->release_list, &release_list); |
4430 | need_schedule_work = 1; |
4431 | } |
4432 | spin_unlock(&release_list_lock); |
4433 | if (need_schedule_work) |
4434 | schedule_work(&release_agent_work); |
4435 | } |
4436 | } |
4437 | |
4438 | /* Caller must verify that the css is not for root cgroup */ |
4439 | void __css_put(struct cgroup_subsys_state *css, int count) |
4440 | { |
4441 | struct cgroup *cgrp = css->cgroup; |
4442 | int val; |
4443 | rcu_read_lock(); |
4444 | val = atomic_sub_return(count, &css->refcnt); |
4445 | if (val == 1) { |
4446 | if (notify_on_release(cgrp)) { |
4447 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
4448 | check_for_release(cgrp); |
4449 | } |
4450 | cgroup_wakeup_rmdir_waiter(cgrp); |
4451 | } |
4452 | rcu_read_unlock(); |
4453 | WARN_ON_ONCE(val < 1); |
4454 | } |
4455 | EXPORT_SYMBOL_GPL(__css_put); |
4456 | |
4457 | /* |
4458 | * Notify userspace when a cgroup is released, by running the |
4459 | * configured release agent with the name of the cgroup (path |
4460 | * relative to the root of cgroup file system) as the argument. |
4461 | * |
4462 | * Most likely, this user command will try to rmdir this cgroup. |
4463 | * |
4464 | * This races with the possibility that some other task will be |
4465 | * attached to this cgroup before it is removed, or that some other |
4466 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. |
4467 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer |
4468 | * unused, and this cgroup will be reprieved from its death sentence, |
4469 | * to continue to serve a useful existence. Next time it's released, |
4470 | * we will get notified again, if it still has 'notify_on_release' set. |
4471 | * |
4472 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which |
4473 | * means only wait until the task is successfully execve()'d. The |
4474 | * separate release agent task is forked by call_usermodehelper(), |
4475 | * then control in this thread returns here, without waiting for the |
4476 | * release agent task. We don't bother to wait because the caller of |
4477 | * this routine has no use for the exit status of the release agent |
4478 | * task, so no sense holding our caller up for that. |
4479 | */ |
4480 | static void cgroup_release_agent(struct work_struct *work) |
4481 | { |
4482 | BUG_ON(work != &release_agent_work); |
4483 | mutex_lock(&cgroup_mutex); |
4484 | spin_lock(&release_list_lock); |
4485 | while (!list_empty(&release_list)) { |
4486 | char *argv[3], *envp[3]; |
4487 | int i; |
4488 | char *pathbuf = NULL, *agentbuf = NULL; |
4489 | struct cgroup *cgrp = list_entry(release_list.next, |
4490 | struct cgroup, |
4491 | release_list); |
4492 | list_del_init(&cgrp->release_list); |
4493 | spin_unlock(&release_list_lock); |
4494 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
4495 | if (!pathbuf) |
4496 | goto continue_free; |
4497 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) |
4498 | goto continue_free; |
4499 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); |
4500 | if (!agentbuf) |
4501 | goto continue_free; |
4502 | |
4503 | i = 0; |
4504 | argv[i++] = agentbuf; |
4505 | argv[i++] = pathbuf; |
4506 | argv[i] = NULL; |
4507 | |
4508 | i = 0; |
4509 | /* minimal command environment */ |
4510 | envp[i++] = "HOME=/"; |
4511 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; |
4512 | envp[i] = NULL; |
4513 | |
4514 | /* Drop the lock while we invoke the usermode helper, |
4515 | * since the exec could involve hitting disk and hence |
4516 | * be a slow process */ |
4517 | mutex_unlock(&cgroup_mutex); |
4518 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
4519 | mutex_lock(&cgroup_mutex); |
4520 | continue_free: |
4521 | kfree(pathbuf); |
4522 | kfree(agentbuf); |
4523 | spin_lock(&release_list_lock); |
4524 | } |
4525 | spin_unlock(&release_list_lock); |
4526 | mutex_unlock(&cgroup_mutex); |
4527 | } |
4528 | |
4529 | static int __init cgroup_disable(char *str) |
4530 | { |
4531 | int i; |
4532 | char *token; |
4533 | |
4534 | while ((token = strsep(&str, ",")) != NULL) { |
4535 | if (!*token) |
4536 | continue; |
4537 | /* |
4538 | * cgroup_disable, being at boot time, can't know about module |
4539 | * subsystems, so we don't worry about them. |
4540 | */ |
4541 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { |
4542 | struct cgroup_subsys *ss = subsys[i]; |
4543 | |
4544 | if (!strcmp(token, ss->name)) { |
4545 | ss->disabled = 1; |
4546 | printk(KERN_INFO "Disabling %s control group" |
4547 | " subsystem\n", ss->name); |
4548 | break; |
4549 | } |
4550 | } |
4551 | } |
4552 | return 1; |
4553 | } |
4554 | __setup("cgroup_disable=", cgroup_disable); |
4555 | |
4556 | /* |
4557 | * Functons for CSS ID. |
4558 | */ |
4559 | |
4560 | /* |
4561 | *To get ID other than 0, this should be called when !cgroup_is_removed(). |
4562 | */ |
4563 | unsigned short css_id(struct cgroup_subsys_state *css) |
4564 | { |
4565 | struct css_id *cssid; |
4566 | |
4567 | /* |
4568 | * This css_id() can return correct value when somone has refcnt |
4569 | * on this or this is under rcu_read_lock(). Once css->id is allocated, |
4570 | * it's unchanged until freed. |
4571 | */ |
4572 | cssid = rcu_dereference_check(css->id, |
4573 | rcu_read_lock_held() || atomic_read(&css->refcnt)); |
4574 | |
4575 | if (cssid) |
4576 | return cssid->id; |
4577 | return 0; |
4578 | } |
4579 | EXPORT_SYMBOL_GPL(css_id); |
4580 | |
4581 | unsigned short css_depth(struct cgroup_subsys_state *css) |
4582 | { |
4583 | struct css_id *cssid; |
4584 | |
4585 | cssid = rcu_dereference_check(css->id, |
4586 | rcu_read_lock_held() || atomic_read(&css->refcnt)); |
4587 | |
4588 | if (cssid) |
4589 | return cssid->depth; |
4590 | return 0; |
4591 | } |
4592 | EXPORT_SYMBOL_GPL(css_depth); |
4593 | |
4594 | /** |
4595 | * css_is_ancestor - test "root" css is an ancestor of "child" |
4596 | * @child: the css to be tested. |
4597 | * @root: the css supporsed to be an ancestor of the child. |
4598 | * |
4599 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because |
4600 | * this function reads css->id, this use rcu_dereference() and rcu_read_lock(). |
4601 | * But, considering usual usage, the csses should be valid objects after test. |
4602 | * Assuming that the caller will do some action to the child if this returns |
4603 | * returns true, the caller must take "child";s reference count. |
4604 | * If "child" is valid object and this returns true, "root" is valid, too. |
4605 | */ |
4606 | |
4607 | bool css_is_ancestor(struct cgroup_subsys_state *child, |
4608 | const struct cgroup_subsys_state *root) |
4609 | { |
4610 | struct css_id *child_id; |
4611 | struct css_id *root_id; |
4612 | bool ret = true; |
4613 | |
4614 | rcu_read_lock(); |
4615 | child_id = rcu_dereference(child->id); |
4616 | root_id = rcu_dereference(root->id); |
4617 | if (!child_id |
4618 | || !root_id |
4619 | || (child_id->depth < root_id->depth) |
4620 | || (child_id->stack[root_id->depth] != root_id->id)) |
4621 | ret = false; |
4622 | rcu_read_unlock(); |
4623 | return ret; |
4624 | } |
4625 | |
4626 | static void __free_css_id_cb(struct rcu_head *head) |
4627 | { |
4628 | struct css_id *id; |
4629 | |
4630 | id = container_of(head, struct css_id, rcu_head); |
4631 | kfree(id); |
4632 | } |
4633 | |
4634 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
4635 | { |
4636 | struct css_id *id = css->id; |
4637 | /* When this is called before css_id initialization, id can be NULL */ |
4638 | if (!id) |
4639 | return; |
4640 | |
4641 | BUG_ON(!ss->use_id); |
4642 | |
4643 | rcu_assign_pointer(id->css, NULL); |
4644 | rcu_assign_pointer(css->id, NULL); |
4645 | spin_lock(&ss->id_lock); |
4646 | idr_remove(&ss->idr, id->id); |
4647 | spin_unlock(&ss->id_lock); |
4648 | call_rcu(&id->rcu_head, __free_css_id_cb); |
4649 | } |
4650 | EXPORT_SYMBOL_GPL(free_css_id); |
4651 | |
4652 | /* |
4653 | * This is called by init or create(). Then, calls to this function are |
4654 | * always serialized (By cgroup_mutex() at create()). |
4655 | */ |
4656 | |
4657 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) |
4658 | { |
4659 | struct css_id *newid; |
4660 | int myid, error, size; |
4661 | |
4662 | BUG_ON(!ss->use_id); |
4663 | |
4664 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); |
4665 | newid = kzalloc(size, GFP_KERNEL); |
4666 | if (!newid) |
4667 | return ERR_PTR(-ENOMEM); |
4668 | /* get id */ |
4669 | if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) { |
4670 | error = -ENOMEM; |
4671 | goto err_out; |
4672 | } |
4673 | spin_lock(&ss->id_lock); |
4674 | /* Don't use 0. allocates an ID of 1-65535 */ |
4675 | error = idr_get_new_above(&ss->idr, newid, 1, &myid); |
4676 | spin_unlock(&ss->id_lock); |
4677 | |
4678 | /* Returns error when there are no free spaces for new ID.*/ |
4679 | if (error) { |
4680 | error = -ENOSPC; |
4681 | goto err_out; |
4682 | } |
4683 | if (myid > CSS_ID_MAX) |
4684 | goto remove_idr; |
4685 | |
4686 | newid->id = myid; |
4687 | newid->depth = depth; |
4688 | return newid; |
4689 | remove_idr: |
4690 | error = -ENOSPC; |
4691 | spin_lock(&ss->id_lock); |
4692 | idr_remove(&ss->idr, myid); |
4693 | spin_unlock(&ss->id_lock); |
4694 | err_out: |
4695 | kfree(newid); |
4696 | return ERR_PTR(error); |
4697 | |
4698 | } |
4699 | |
4700 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
4701 | struct cgroup_subsys_state *rootcss) |
4702 | { |
4703 | struct css_id *newid; |
4704 | |
4705 | spin_lock_init(&ss->id_lock); |
4706 | idr_init(&ss->idr); |
4707 | |
4708 | newid = get_new_cssid(ss, 0); |
4709 | if (IS_ERR(newid)) |
4710 | return PTR_ERR(newid); |
4711 | |
4712 | newid->stack[0] = newid->id; |
4713 | newid->css = rootcss; |
4714 | rootcss->id = newid; |
4715 | return 0; |
4716 | } |
4717 | |
4718 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, |
4719 | struct cgroup *child) |
4720 | { |
4721 | int subsys_id, i, depth = 0; |
4722 | struct cgroup_subsys_state *parent_css, *child_css; |
4723 | struct css_id *child_id, *parent_id; |
4724 | |
4725 | subsys_id = ss->subsys_id; |
4726 | parent_css = parent->subsys[subsys_id]; |
4727 | child_css = child->subsys[subsys_id]; |
4728 | parent_id = parent_css->id; |
4729 | depth = parent_id->depth + 1; |
4730 | |
4731 | child_id = get_new_cssid(ss, depth); |
4732 | if (IS_ERR(child_id)) |
4733 | return PTR_ERR(child_id); |
4734 | |
4735 | for (i = 0; i < depth; i++) |
4736 | child_id->stack[i] = parent_id->stack[i]; |
4737 | child_id->stack[depth] = child_id->id; |
4738 | /* |
4739 | * child_id->css pointer will be set after this cgroup is available |
4740 | * see cgroup_populate_dir() |
4741 | */ |
4742 | rcu_assign_pointer(child_css->id, child_id); |
4743 | |
4744 | return 0; |
4745 | } |
4746 | |
4747 | /** |
4748 | * css_lookup - lookup css by id |
4749 | * @ss: cgroup subsys to be looked into. |
4750 | * @id: the id |
4751 | * |
4752 | * Returns pointer to cgroup_subsys_state if there is valid one with id. |
4753 | * NULL if not. Should be called under rcu_read_lock() |
4754 | */ |
4755 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) |
4756 | { |
4757 | struct css_id *cssid = NULL; |
4758 | |
4759 | BUG_ON(!ss->use_id); |
4760 | cssid = idr_find(&ss->idr, id); |
4761 | |
4762 | if (unlikely(!cssid)) |
4763 | return NULL; |
4764 | |
4765 | return rcu_dereference(cssid->css); |
4766 | } |
4767 | EXPORT_SYMBOL_GPL(css_lookup); |
4768 | |
4769 | /** |
4770 | * css_get_next - lookup next cgroup under specified hierarchy. |
4771 | * @ss: pointer to subsystem |
4772 | * @id: current position of iteration. |
4773 | * @root: pointer to css. search tree under this. |
4774 | * @foundid: position of found object. |
4775 | * |
4776 | * Search next css under the specified hierarchy of rootid. Calling under |
4777 | * rcu_read_lock() is necessary. Returns NULL if it reaches the end. |
4778 | */ |
4779 | struct cgroup_subsys_state * |
4780 | css_get_next(struct cgroup_subsys *ss, int id, |
4781 | struct cgroup_subsys_state *root, int *foundid) |
4782 | { |
4783 | struct cgroup_subsys_state *ret = NULL; |
4784 | struct css_id *tmp; |
4785 | int tmpid; |
4786 | int rootid = css_id(root); |
4787 | int depth = css_depth(root); |
4788 | |
4789 | if (!rootid) |
4790 | return NULL; |
4791 | |
4792 | BUG_ON(!ss->use_id); |
4793 | /* fill start point for scan */ |
4794 | tmpid = id; |
4795 | while (1) { |
4796 | /* |
4797 | * scan next entry from bitmap(tree), tmpid is updated after |
4798 | * idr_get_next(). |
4799 | */ |
4800 | spin_lock(&ss->id_lock); |
4801 | tmp = idr_get_next(&ss->idr, &tmpid); |
4802 | spin_unlock(&ss->id_lock); |
4803 | |
4804 | if (!tmp) |
4805 | break; |
4806 | if (tmp->depth >= depth && tmp->stack[depth] == rootid) { |
4807 | ret = rcu_dereference(tmp->css); |
4808 | if (ret) { |
4809 | *foundid = tmpid; |
4810 | break; |
4811 | } |
4812 | } |
4813 | /* continue to scan from next id */ |
4814 | tmpid = tmpid + 1; |
4815 | } |
4816 | return ret; |
4817 | } |
4818 | |
4819 | /* |
4820 | * get corresponding css from file open on cgroupfs directory |
4821 | */ |
4822 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) |
4823 | { |
4824 | struct cgroup *cgrp; |
4825 | struct inode *inode; |
4826 | struct cgroup_subsys_state *css; |
4827 | |
4828 | inode = f->f_dentry->d_inode; |
4829 | /* check in cgroup filesystem dir */ |
4830 | if (inode->i_op != &cgroup_dir_inode_operations) |
4831 | return ERR_PTR(-EBADF); |
4832 | |
4833 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) |
4834 | return ERR_PTR(-EINVAL); |
4835 | |
4836 | /* get cgroup */ |
4837 | cgrp = __d_cgrp(f->f_dentry); |
4838 | css = cgrp->subsys[id]; |
4839 | return css ? css : ERR_PTR(-ENOENT); |
4840 | } |
4841 | |
4842 | #ifdef CONFIG_CGROUP_DEBUG |
4843 | static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss, |
4844 | struct cgroup *cont) |
4845 | { |
4846 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); |
4847 | |
4848 | if (!css) |
4849 | return ERR_PTR(-ENOMEM); |
4850 | |
4851 | return css; |
4852 | } |
4853 | |
4854 | static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont) |
4855 | { |
4856 | kfree(cont->subsys[debug_subsys_id]); |
4857 | } |
4858 | |
4859 | static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) |
4860 | { |
4861 | return atomic_read(&cont->count); |
4862 | } |
4863 | |
4864 | static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) |
4865 | { |
4866 | return cgroup_task_count(cont); |
4867 | } |
4868 | |
4869 | static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) |
4870 | { |
4871 | return (u64)(unsigned long)current->cgroups; |
4872 | } |
4873 | |
4874 | static u64 current_css_set_refcount_read(struct cgroup *cont, |
4875 | struct cftype *cft) |
4876 | { |
4877 | u64 count; |
4878 | |
4879 | rcu_read_lock(); |
4880 | count = atomic_read(¤t->cgroups->refcount); |
4881 | rcu_read_unlock(); |
4882 | return count; |
4883 | } |
4884 | |
4885 | static int current_css_set_cg_links_read(struct cgroup *cont, |
4886 | struct cftype *cft, |
4887 | struct seq_file *seq) |
4888 | { |
4889 | struct cg_cgroup_link *link; |
4890 | struct css_set *cg; |
4891 | |
4892 | read_lock(&css_set_lock); |
4893 | rcu_read_lock(); |
4894 | cg = rcu_dereference(current->cgroups); |
4895 | list_for_each_entry(link, &cg->cg_links, cg_link_list) { |
4896 | struct cgroup *c = link->cgrp; |
4897 | const char *name; |
4898 | |
4899 | if (c->dentry) |
4900 | name = c->dentry->d_name.name; |
4901 | else |
4902 | name = "?"; |
4903 | seq_printf(seq, "Root %d group %s\n", |
4904 | c->root->hierarchy_id, name); |
4905 | } |
4906 | rcu_read_unlock(); |
4907 | read_unlock(&css_set_lock); |
4908 | return 0; |
4909 | } |
4910 | |
4911 | #define MAX_TASKS_SHOWN_PER_CSS 25 |
4912 | static int cgroup_css_links_read(struct cgroup *cont, |
4913 | struct cftype *cft, |
4914 | struct seq_file *seq) |
4915 | { |
4916 | struct cg_cgroup_link *link; |
4917 | |
4918 | read_lock(&css_set_lock); |
4919 | list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { |
4920 | struct css_set *cg = link->cg; |
4921 | struct task_struct *task; |
4922 | int count = 0; |
4923 | seq_printf(seq, "css_set %p\n", cg); |
4924 | list_for_each_entry(task, &cg->tasks, cg_list) { |
4925 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { |
4926 | seq_puts(seq, " ...\n"); |
4927 | break; |
4928 | } else { |
4929 | seq_printf(seq, " task %d\n", |
4930 | task_pid_vnr(task)); |
4931 | } |
4932 | } |
4933 | } |
4934 | read_unlock(&css_set_lock); |
4935 | return 0; |
4936 | } |
4937 | |
4938 | static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) |
4939 | { |
4940 | return test_bit(CGRP_RELEASABLE, &cgrp->flags); |
4941 | } |
4942 | |
4943 | static struct cftype debug_files[] = { |
4944 | { |
4945 | .name = "cgroup_refcount", |
4946 | .read_u64 = cgroup_refcount_read, |
4947 | }, |
4948 | { |
4949 | .name = "taskcount", |
4950 | .read_u64 = debug_taskcount_read, |
4951 | }, |
4952 | |
4953 | { |
4954 | .name = "current_css_set", |
4955 | .read_u64 = current_css_set_read, |
4956 | }, |
4957 | |
4958 | { |
4959 | .name = "current_css_set_refcount", |
4960 | .read_u64 = current_css_set_refcount_read, |
4961 | }, |
4962 | |
4963 | { |
4964 | .name = "current_css_set_cg_links", |
4965 | .read_seq_string = current_css_set_cg_links_read, |
4966 | }, |
4967 | |
4968 | { |
4969 | .name = "cgroup_css_links", |
4970 | .read_seq_string = cgroup_css_links_read, |
4971 | }, |
4972 | |
4973 | { |
4974 | .name = "releasable", |
4975 | .read_u64 = releasable_read, |
4976 | }, |
4977 | }; |
4978 | |
4979 | static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont) |
4980 | { |
4981 | return cgroup_add_files(cont, ss, debug_files, |
4982 | ARRAY_SIZE(debug_files)); |
4983 | } |
4984 | |
4985 | struct cgroup_subsys debug_subsys = { |
4986 | .name = "debug", |
4987 | .create = debug_create, |
4988 | .destroy = debug_destroy, |
4989 | .populate = debug_populate, |
4990 | .subsys_id = debug_subsys_id, |
4991 | }; |
4992 | #endif /* CONFIG_CGROUP_DEBUG */ |
4993 |
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