2 * Generic process-grouping system.
4 * Based originally on the cpuset system, extracted by Paul Menage
5 * Copyright (C) 2006 Google, Inc
7 * Notifications support
8 * Copyright (C) 2009 Nokia Corporation
9 * Author: Kirill A. Shutemov
11 * Copyright notices from the original cpuset code:
12 * --------------------------------------------------
13 * Copyright (C) 2003 BULL SA.
14 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
16 * Portions derived from Patrick Mochel's sysfs code.
17 * sysfs is Copyright (c) 2001-3 Patrick Mochel
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 * ---------------------------------------------------
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.
29 #include <linux/cgroup.h>
30 #include <linux/cred.h>
31 #include <linux/ctype.h>
32 #include <linux/errno.h>
33 #include <linux/init_task.h>
34 #include <linux/kernel.h>
35 #include <linux/list.h>
37 #include <linux/mutex.h>
38 #include <linux/mount.h>
39 #include <linux/pagemap.h>
40 #include <linux/proc_fs.h>
41 #include <linux/rcupdate.h>
42 #include <linux/sched.h>
43 #include <linux/backing-dev.h>
44 #include <linux/seq_file.h>
45 #include <linux/slab.h>
46 #include <linux/magic.h>
47 #include <linux/spinlock.h>
48 #include <linux/string.h>
49 #include <linux/sort.h>
50 #include <linux/kmod.h>
51 #include <linux/module.h>
52 #include <linux/delayacct.h>
53 #include <linux/cgroupstats.h>
54 #include <linux/hashtable.h>
55 #include <linux/namei.h>
56 #include <linux/pid_namespace.h>
57 #include <linux/idr.h>
58 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
59 #include <linux/eventfd.h>
60 #include <linux/poll.h>
61 #include <linux/flex_array.h> /* used in cgroup_attach_task */
62 #include <linux/kthread.h>
64 #include <linux/atomic.h>
66 /* css deactivation bias, makes css->refcnt negative to deny new trygets */
67 #define CSS_DEACT_BIAS INT_MIN
70 * cgroup_mutex is the master lock. Any modification to cgroup or its
71 * hierarchy must be performed while holding it.
73 * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify
74 * cgroupfs_root of any cgroup hierarchy - subsys list, flags,
75 * release_agent_path and so on. Modifying requires both cgroup_mutex and
76 * cgroup_root_mutex. Readers can acquire either of the two. This is to
77 * break the following locking order cycle.
79 * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem
80 * B. namespace_sem -> cgroup_mutex
82 * B happens only through cgroup_show_options() and using cgroup_root_mutex
85 #ifdef CONFIG_PROVE_RCU
86 DEFINE_MUTEX(cgroup_mutex
);
87 EXPORT_SYMBOL_GPL(cgroup_mutex
); /* only for task_subsys_state_check() */
89 static DEFINE_MUTEX(cgroup_mutex
);
92 static DEFINE_MUTEX(cgroup_root_mutex
);
95 * Generate an array of cgroup subsystem pointers. At boot time, this is
96 * populated with the built in subsystems, and modular subsystems are
97 * registered after that. The mutable section of this array is protected by
100 #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
101 #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
102 static struct cgroup_subsys
*subsys
[CGROUP_SUBSYS_COUNT
] = {
103 #include <linux/cgroup_subsys.h>
107 * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
108 * subsystems that are otherwise unattached - it never has more than a
109 * single cgroup, and all tasks are part of that cgroup.
111 static struct cgroupfs_root rootnode
;
114 * cgroupfs file entry, pointed to from leaf dentry->d_fsdata.
117 struct list_head node
;
118 struct dentry
*dentry
;
122 struct simple_xattrs xattrs
;
126 * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
127 * cgroup_subsys->use_id != 0.
129 #define CSS_ID_MAX (65535)
132 * The css to which this ID points. This pointer is set to valid value
133 * after cgroup is populated. If cgroup is removed, this will be NULL.
134 * This pointer is expected to be RCU-safe because destroy()
135 * is called after synchronize_rcu(). But for safe use, css_tryget()
136 * should be used for avoiding race.
138 struct cgroup_subsys_state __rcu
*css
;
144 * Depth in hierarchy which this ID belongs to.
146 unsigned short depth
;
148 * ID is freed by RCU. (and lookup routine is RCU safe.)
150 struct rcu_head rcu_head
;
152 * Hierarchy of CSS ID belongs to.
154 unsigned short stack
[0]; /* Array of Length (depth+1) */
158 * cgroup_event represents events which userspace want to receive.
160 struct cgroup_event
{
162 * Cgroup which the event belongs to.
166 * Control file which the event associated.
170 * eventfd to signal userspace about the event.
172 struct eventfd_ctx
*eventfd
;
174 * Each of these stored in a list by the cgroup.
176 struct list_head list
;
178 * All fields below needed to unregister event when
179 * userspace closes eventfd.
182 wait_queue_head_t
*wqh
;
184 struct work_struct remove
;
187 /* The list of hierarchy roots */
189 static LIST_HEAD(roots
);
190 static int root_count
;
193 * Hierarchy ID allocation and mapping. It follows the same exclusion
194 * rules as other root ops - both cgroup_mutex and cgroup_root_mutex for
195 * writes, either for reads.
197 static DEFINE_IDR(cgroup_hierarchy_idr
);
199 /* dummytop is a shorthand for the dummy hierarchy's top cgroup */
200 #define dummytop (&rootnode.top_cgroup)
202 static struct cgroup_name root_cgroup_name
= { .name
= "/" };
204 /* This flag indicates whether tasks in the fork and exit paths should
205 * check for fork/exit handlers to call. This avoids us having to do
206 * extra work in the fork/exit path if none of the subsystems need to
209 static int need_forkexit_callback __read_mostly
;
211 static int cgroup_destroy_locked(struct cgroup
*cgrp
);
212 static int cgroup_addrm_files(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
213 struct cftype cfts
[], bool is_add
);
215 static int css_unbias_refcnt(int refcnt
)
217 return refcnt
>= 0 ? refcnt
: refcnt
- CSS_DEACT_BIAS
;
220 /* the current nr of refs, always >= 0 whether @css is deactivated or not */
221 static int css_refcnt(struct cgroup_subsys_state
*css
)
223 int v
= atomic_read(&css
->refcnt
);
225 return css_unbias_refcnt(v
);
228 /* convenient tests for these bits */
229 static inline bool cgroup_is_removed(const struct cgroup
*cgrp
)
231 return test_bit(CGRP_REMOVED
, &cgrp
->flags
);
235 * cgroup_is_descendant - test ancestry
236 * @cgrp: the cgroup to be tested
237 * @ancestor: possible ancestor of @cgrp
239 * Test whether @cgrp is a descendant of @ancestor. It also returns %true
240 * if @cgrp == @ancestor. This function is safe to call as long as @cgrp
241 * and @ancestor are accessible.
243 bool cgroup_is_descendant(struct cgroup
*cgrp
, struct cgroup
*ancestor
)
246 if (cgrp
== ancestor
)
252 EXPORT_SYMBOL_GPL(cgroup_is_descendant
);
254 static int cgroup_is_releasable(const struct cgroup
*cgrp
)
257 (1 << CGRP_RELEASABLE
) |
258 (1 << CGRP_NOTIFY_ON_RELEASE
);
259 return (cgrp
->flags
& bits
) == bits
;
262 static int notify_on_release(const struct cgroup
*cgrp
)
264 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
268 * for_each_subsys() allows you to iterate on each subsystem attached to
269 * an active hierarchy
271 #define for_each_subsys(_root, _ss) \
272 list_for_each_entry(_ss, &_root->subsys_list, sibling)
274 /* for_each_active_root() allows you to iterate across the active hierarchies */
275 #define for_each_active_root(_root) \
276 list_for_each_entry(_root, &roots, root_list)
278 static inline struct cgroup
*__d_cgrp(struct dentry
*dentry
)
280 return dentry
->d_fsdata
;
283 static inline struct cfent
*__d_cfe(struct dentry
*dentry
)
285 return dentry
->d_fsdata
;
288 static inline struct cftype
*__d_cft(struct dentry
*dentry
)
290 return __d_cfe(dentry
)->type
;
294 * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
295 * @cgrp: the cgroup to be checked for liveness
297 * On success, returns true; the mutex should be later unlocked. On
298 * failure returns false with no lock held.
300 static bool cgroup_lock_live_group(struct cgroup
*cgrp
)
302 mutex_lock(&cgroup_mutex
);
303 if (cgroup_is_removed(cgrp
)) {
304 mutex_unlock(&cgroup_mutex
);
310 /* the list of cgroups eligible for automatic release. Protected by
311 * release_list_lock */
312 static LIST_HEAD(release_list
);
313 static DEFINE_RAW_SPINLOCK(release_list_lock
);
314 static void cgroup_release_agent(struct work_struct
*work
);
315 static DECLARE_WORK(release_agent_work
, cgroup_release_agent
);
316 static void check_for_release(struct cgroup
*cgrp
);
319 * A cgroup can be associated with multiple css_sets as different tasks may
320 * belong to different cgroups on different hierarchies. In the other
321 * direction, a css_set is naturally associated with multiple cgroups.
322 * This M:N relationship is represented by the following link structure
323 * which exists for each association and allows traversing the associations
326 struct cgrp_cset_link
{
327 /* the cgroup and css_set this link associates */
329 struct css_set
*cset
;
331 /* list of cgrp_cset_links anchored at cgrp->cset_links */
332 struct list_head cset_link
;
334 /* list of cgrp_cset_links anchored at css_set->cgrp_links */
335 struct list_head cgrp_link
;
338 /* The default css_set - used by init and its children prior to any
339 * hierarchies being mounted. It contains a pointer to the root state
340 * for each subsystem. Also used to anchor the list of css_sets. Not
341 * reference-counted, to improve performance when child cgroups
342 * haven't been created.
345 static struct css_set init_css_set
;
346 static struct cgrp_cset_link init_cgrp_cset_link
;
348 static int cgroup_init_idr(struct cgroup_subsys
*ss
,
349 struct cgroup_subsys_state
*css
);
351 /* css_set_lock protects the list of css_set objects, and the
352 * chain of tasks off each css_set. Nests outside task->alloc_lock
353 * due to cgroup_iter_start() */
354 static DEFINE_RWLOCK(css_set_lock
);
355 static int css_set_count
;
358 * hash table for cgroup groups. This improves the performance to find
359 * an existing css_set. This hash doesn't (currently) take into
360 * account cgroups in empty hierarchies.
362 #define CSS_SET_HASH_BITS 7
363 static DEFINE_HASHTABLE(css_set_table
, CSS_SET_HASH_BITS
);
365 static unsigned long css_set_hash(struct cgroup_subsys_state
*css
[])
368 unsigned long key
= 0UL;
370 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++)
371 key
+= (unsigned long)css
[i
];
372 key
= (key
>> 16) ^ key
;
377 /* We don't maintain the lists running through each css_set to its
378 * task until after the first call to cgroup_iter_start(). This
379 * reduces the fork()/exit() overhead for people who have cgroups
380 * compiled into their kernel but not actually in use */
381 static int use_task_css_set_links __read_mostly
;
383 static void __put_css_set(struct css_set
*cset
, int taskexit
)
385 struct cgrp_cset_link
*link
, *tmp_link
;
388 * Ensure that the refcount doesn't hit zero while any readers
389 * can see it. Similar to atomic_dec_and_lock(), but for an
392 if (atomic_add_unless(&cset
->refcount
, -1, 1))
394 write_lock(&css_set_lock
);
395 if (!atomic_dec_and_test(&cset
->refcount
)) {
396 write_unlock(&css_set_lock
);
400 /* This css_set is dead. unlink it and release cgroup refcounts */
401 hash_del(&cset
->hlist
);
404 list_for_each_entry_safe(link
, tmp_link
, &cset
->cgrp_links
, cgrp_link
) {
405 struct cgroup
*cgrp
= link
->cgrp
;
407 list_del(&link
->cset_link
);
408 list_del(&link
->cgrp_link
);
411 * We may not be holding cgroup_mutex, and if cgrp->count is
412 * dropped to 0 the cgroup can be destroyed at any time, hence
413 * rcu_read_lock is used to keep it alive.
416 if (atomic_dec_and_test(&cgrp
->count
) &&
417 notify_on_release(cgrp
)) {
419 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
420 check_for_release(cgrp
);
427 write_unlock(&css_set_lock
);
428 kfree_rcu(cset
, rcu_head
);
432 * refcounted get/put for css_set objects
434 static inline void get_css_set(struct css_set
*cset
)
436 atomic_inc(&cset
->refcount
);
439 static inline void put_css_set(struct css_set
*cset
)
441 __put_css_set(cset
, 0);
444 static inline void put_css_set_taskexit(struct css_set
*cset
)
446 __put_css_set(cset
, 1);
450 * compare_css_sets - helper function for find_existing_css_set().
451 * @cset: candidate css_set being tested
452 * @old_cset: existing css_set for a task
453 * @new_cgrp: cgroup that's being entered by the task
454 * @template: desired set of css pointers in css_set (pre-calculated)
456 * Returns true if "cg" matches "old_cg" except for the hierarchy
457 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
459 static bool compare_css_sets(struct css_set
*cset
,
460 struct css_set
*old_cset
,
461 struct cgroup
*new_cgrp
,
462 struct cgroup_subsys_state
*template[])
464 struct list_head
*l1
, *l2
;
466 if (memcmp(template, cset
->subsys
, sizeof(cset
->subsys
))) {
467 /* Not all subsystems matched */
472 * Compare cgroup pointers in order to distinguish between
473 * different cgroups in heirarchies with no subsystems. We
474 * could get by with just this check alone (and skip the
475 * memcmp above) but on most setups the memcmp check will
476 * avoid the need for this more expensive check on almost all
480 l1
= &cset
->cgrp_links
;
481 l2
= &old_cset
->cgrp_links
;
483 struct cgrp_cset_link
*link1
, *link2
;
484 struct cgroup
*cgrp1
, *cgrp2
;
488 /* See if we reached the end - both lists are equal length. */
489 if (l1
== &cset
->cgrp_links
) {
490 BUG_ON(l2
!= &old_cset
->cgrp_links
);
493 BUG_ON(l2
== &old_cset
->cgrp_links
);
495 /* Locate the cgroups associated with these links. */
496 link1
= list_entry(l1
, struct cgrp_cset_link
, cgrp_link
);
497 link2
= list_entry(l2
, struct cgrp_cset_link
, cgrp_link
);
500 /* Hierarchies should be linked in the same order. */
501 BUG_ON(cgrp1
->root
!= cgrp2
->root
);
504 * If this hierarchy is the hierarchy of the cgroup
505 * that's changing, then we need to check that this
506 * css_set points to the new cgroup; if it's any other
507 * hierarchy, then this css_set should point to the
508 * same cgroup as the old css_set.
510 if (cgrp1
->root
== new_cgrp
->root
) {
511 if (cgrp1
!= new_cgrp
)
522 * find_existing_css_set() is a helper for
523 * find_css_set(), and checks to see whether an existing
524 * css_set is suitable.
526 * oldcg: the cgroup group that we're using before the cgroup
529 * cgrp: the cgroup that we're moving into
531 * template: location in which to build the desired set of subsystem
532 * state objects for the new cgroup group
534 static struct css_set
*find_existing_css_set(struct css_set
*old_cset
,
536 struct cgroup_subsys_state
*template[])
539 struct cgroupfs_root
*root
= cgrp
->root
;
540 struct css_set
*cset
;
544 * Build the set of subsystem state objects that we want to see in the
545 * new css_set. while subsystems can change globally, the entries here
546 * won't change, so no need for locking.
548 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
549 if (root
->subsys_mask
& (1UL << i
)) {
550 /* Subsystem is in this hierarchy. So we want
551 * the subsystem state from the new
553 template[i
] = cgrp
->subsys
[i
];
555 /* Subsystem is not in this hierarchy, so we
556 * don't want to change the subsystem state */
557 template[i
] = old_cset
->subsys
[i
];
561 key
= css_set_hash(template);
562 hash_for_each_possible(css_set_table
, cset
, hlist
, key
) {
563 if (!compare_css_sets(cset
, old_cset
, cgrp
, template))
566 /* This css_set matches what we need */
570 /* No existing cgroup group matched */
574 static void free_cgrp_cset_links(struct list_head
*links_to_free
)
576 struct cgrp_cset_link
*link
, *tmp_link
;
578 list_for_each_entry_safe(link
, tmp_link
, links_to_free
, cset_link
) {
579 list_del(&link
->cset_link
);
585 * allocate_cgrp_cset_links - allocate cgrp_cset_links
586 * @count: the number of links to allocate
587 * @tmp_links: list_head the allocated links are put on
589 * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
590 * through ->cset_link. Returns 0 on success or -errno.
592 static int allocate_cgrp_cset_links(int count
, struct list_head
*tmp_links
)
594 struct cgrp_cset_link
*link
;
597 INIT_LIST_HEAD(tmp_links
);
599 for (i
= 0; i
< count
; i
++) {
600 link
= kzalloc(sizeof(*link
), GFP_KERNEL
);
602 free_cgrp_cset_links(tmp_links
);
605 list_add(&link
->cset_link
, tmp_links
);
611 * link_css_set - a helper function to link a css_set to a cgroup
612 * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
613 * @cset: the css_set to be linked
614 * @cgrp: the destination cgroup
616 static void link_css_set(struct list_head
*tmp_links
, struct css_set
*cset
,
619 struct cgrp_cset_link
*link
;
621 BUG_ON(list_empty(tmp_links
));
622 link
= list_first_entry(tmp_links
, struct cgrp_cset_link
, cset_link
);
625 atomic_inc(&cgrp
->count
);
626 list_move(&link
->cset_link
, &cgrp
->cset_links
);
628 * Always add links to the tail of the list so that the list
629 * is sorted by order of hierarchy creation
631 list_add_tail(&link
->cgrp_link
, &cset
->cgrp_links
);
635 * find_css_set() takes an existing cgroup group and a
636 * cgroup object, and returns a css_set object that's
637 * equivalent to the old group, but with the given cgroup
638 * substituted into the appropriate hierarchy. Must be called with
641 static struct css_set
*find_css_set(struct css_set
*old_cset
,
644 struct css_set
*cset
;
645 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
];
646 struct list_head tmp_links
;
647 struct cgrp_cset_link
*link
;
650 /* First see if we already have a cgroup group that matches
652 read_lock(&css_set_lock
);
653 cset
= find_existing_css_set(old_cset
, cgrp
, template);
656 read_unlock(&css_set_lock
);
661 cset
= kzalloc(sizeof(*cset
), GFP_KERNEL
);
665 /* Allocate all the cgrp_cset_link objects that we'll need */
666 if (allocate_cgrp_cset_links(root_count
, &tmp_links
) < 0) {
671 atomic_set(&cset
->refcount
, 1);
672 INIT_LIST_HEAD(&cset
->cgrp_links
);
673 INIT_LIST_HEAD(&cset
->tasks
);
674 INIT_HLIST_NODE(&cset
->hlist
);
676 /* Copy the set of subsystem state objects generated in
677 * find_existing_css_set() */
678 memcpy(cset
->subsys
, template, sizeof(cset
->subsys
));
680 write_lock(&css_set_lock
);
681 /* Add reference counts and links from the new css_set. */
682 list_for_each_entry(link
, &old_cset
->cgrp_links
, cgrp_link
) {
683 struct cgroup
*c
= link
->cgrp
;
685 if (c
->root
== cgrp
->root
)
687 link_css_set(&tmp_links
, cset
, c
);
690 BUG_ON(!list_empty(&tmp_links
));
694 /* Add this cgroup group to the hash table */
695 key
= css_set_hash(cset
->subsys
);
696 hash_add(css_set_table
, &cset
->hlist
, key
);
698 write_unlock(&css_set_lock
);
704 * Return the cgroup for "task" from the given hierarchy. Must be
705 * called with cgroup_mutex held.
707 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
708 struct cgroupfs_root
*root
)
710 struct css_set
*cset
;
711 struct cgroup
*res
= NULL
;
713 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
714 read_lock(&css_set_lock
);
716 * No need to lock the task - since we hold cgroup_mutex the
717 * task can't change groups, so the only thing that can happen
718 * is that it exits and its css is set back to init_css_set.
720 cset
= task
->cgroups
;
721 if (cset
== &init_css_set
) {
722 res
= &root
->top_cgroup
;
724 struct cgrp_cset_link
*link
;
726 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
727 struct cgroup
*c
= link
->cgrp
;
729 if (c
->root
== root
) {
735 read_unlock(&css_set_lock
);
741 * There is one global cgroup mutex. We also require taking
742 * task_lock() when dereferencing a task's cgroup subsys pointers.
743 * See "The task_lock() exception", at the end of this comment.
745 * A task must hold cgroup_mutex to modify cgroups.
747 * Any task can increment and decrement the count field without lock.
748 * So in general, code holding cgroup_mutex can't rely on the count
749 * field not changing. However, if the count goes to zero, then only
750 * cgroup_attach_task() can increment it again. Because a count of zero
751 * means that no tasks are currently attached, therefore there is no
752 * way a task attached to that cgroup can fork (the other way to
753 * increment the count). So code holding cgroup_mutex can safely
754 * assume that if the count is zero, it will stay zero. Similarly, if
755 * a task holds cgroup_mutex on a cgroup with zero count, it
756 * knows that the cgroup won't be removed, as cgroup_rmdir()
759 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
760 * (usually) take cgroup_mutex. These are the two most performance
761 * critical pieces of code here. The exception occurs on cgroup_exit(),
762 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
763 * is taken, and if the cgroup count is zero, a usermode call made
764 * to the release agent with the name of the cgroup (path relative to
765 * the root of cgroup file system) as the argument.
767 * A cgroup can only be deleted if both its 'count' of using tasks
768 * is zero, and its list of 'children' cgroups is empty. Since all
769 * tasks in the system use _some_ cgroup, and since there is always at
770 * least one task in the system (init, pid == 1), therefore, top_cgroup
771 * always has either children cgroups and/or using tasks. So we don't
772 * need a special hack to ensure that top_cgroup cannot be deleted.
774 * The task_lock() exception
776 * The need for this exception arises from the action of
777 * cgroup_attach_task(), which overwrites one task's cgroup pointer with
778 * another. It does so using cgroup_mutex, however there are
779 * several performance critical places that need to reference
780 * task->cgroup without the expense of grabbing a system global
781 * mutex. Therefore except as noted below, when dereferencing or, as
782 * in cgroup_attach_task(), modifying a task's cgroup pointer we use
783 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
784 * the task_struct routinely used for such matters.
786 * P.S. One more locking exception. RCU is used to guard the
787 * update of a tasks cgroup pointer by cgroup_attach_task()
791 * A couple of forward declarations required, due to cyclic reference loop:
792 * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
793 * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
797 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
);
798 static struct dentry
*cgroup_lookup(struct inode
*, struct dentry
*, unsigned int);
799 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
);
800 static int cgroup_populate_dir(struct cgroup
*cgrp
, bool base_files
,
801 unsigned long subsys_mask
);
802 static const struct inode_operations cgroup_dir_inode_operations
;
803 static const struct file_operations proc_cgroupstats_operations
;
805 static struct backing_dev_info cgroup_backing_dev_info
= {
807 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
,
810 static int alloc_css_id(struct cgroup_subsys
*ss
,
811 struct cgroup
*parent
, struct cgroup
*child
);
813 static struct inode
*cgroup_new_inode(umode_t mode
, struct super_block
*sb
)
815 struct inode
*inode
= new_inode(sb
);
818 inode
->i_ino
= get_next_ino();
819 inode
->i_mode
= mode
;
820 inode
->i_uid
= current_fsuid();
821 inode
->i_gid
= current_fsgid();
822 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
823 inode
->i_mapping
->backing_dev_info
= &cgroup_backing_dev_info
;
828 static struct cgroup_name
*cgroup_alloc_name(struct dentry
*dentry
)
830 struct cgroup_name
*name
;
832 name
= kmalloc(sizeof(*name
) + dentry
->d_name
.len
+ 1, GFP_KERNEL
);
835 strcpy(name
->name
, dentry
->d_name
.name
);
839 static void cgroup_free_fn(struct work_struct
*work
)
841 struct cgroup
*cgrp
= container_of(work
, struct cgroup
, free_work
);
842 struct cgroup_subsys
*ss
;
844 mutex_lock(&cgroup_mutex
);
846 * Release the subsystem state objects.
848 for_each_subsys(cgrp
->root
, ss
)
851 cgrp
->root
->number_of_cgroups
--;
852 mutex_unlock(&cgroup_mutex
);
855 * We get a ref to the parent's dentry, and put the ref when
856 * this cgroup is being freed, so it's guaranteed that the
857 * parent won't be destroyed before its children.
859 dput(cgrp
->parent
->dentry
);
861 ida_simple_remove(&cgrp
->root
->cgroup_ida
, cgrp
->id
);
864 * Drop the active superblock reference that we took when we
865 * created the cgroup. This will free cgrp->root, if we are
866 * holding the last reference to @sb.
868 deactivate_super(cgrp
->root
->sb
);
871 * if we're getting rid of the cgroup, refcount should ensure
872 * that there are no pidlists left.
874 BUG_ON(!list_empty(&cgrp
->pidlists
));
876 simple_xattrs_free(&cgrp
->xattrs
);
878 kfree(rcu_dereference_raw(cgrp
->name
));
882 static void cgroup_free_rcu(struct rcu_head
*head
)
884 struct cgroup
*cgrp
= container_of(head
, struct cgroup
, rcu_head
);
886 schedule_work(&cgrp
->free_work
);
889 static void cgroup_diput(struct dentry
*dentry
, struct inode
*inode
)
891 /* is dentry a directory ? if so, kfree() associated cgroup */
892 if (S_ISDIR(inode
->i_mode
)) {
893 struct cgroup
*cgrp
= dentry
->d_fsdata
;
895 BUG_ON(!(cgroup_is_removed(cgrp
)));
896 call_rcu(&cgrp
->rcu_head
, cgroup_free_rcu
);
898 struct cfent
*cfe
= __d_cfe(dentry
);
899 struct cgroup
*cgrp
= dentry
->d_parent
->d_fsdata
;
901 WARN_ONCE(!list_empty(&cfe
->node
) &&
902 cgrp
!= &cgrp
->root
->top_cgroup
,
903 "cfe still linked for %s\n", cfe
->type
->name
);
904 simple_xattrs_free(&cfe
->xattrs
);
910 static int cgroup_delete(const struct dentry
*d
)
915 static void remove_dir(struct dentry
*d
)
917 struct dentry
*parent
= dget(d
->d_parent
);
920 simple_rmdir(parent
->d_inode
, d
);
924 static void cgroup_rm_file(struct cgroup
*cgrp
, const struct cftype
*cft
)
928 lockdep_assert_held(&cgrp
->dentry
->d_inode
->i_mutex
);
929 lockdep_assert_held(&cgroup_mutex
);
932 * If we're doing cleanup due to failure of cgroup_create(),
933 * the corresponding @cfe may not exist.
935 list_for_each_entry(cfe
, &cgrp
->files
, node
) {
936 struct dentry
*d
= cfe
->dentry
;
938 if (cft
&& cfe
->type
!= cft
)
943 simple_unlink(cgrp
->dentry
->d_inode
, d
);
944 list_del_init(&cfe
->node
);
952 * cgroup_clear_directory - selective removal of base and subsystem files
953 * @dir: directory containing the files
954 * @base_files: true if the base files should be removed
955 * @subsys_mask: mask of the subsystem ids whose files should be removed
957 static void cgroup_clear_directory(struct dentry
*dir
, bool base_files
,
958 unsigned long subsys_mask
)
960 struct cgroup
*cgrp
= __d_cgrp(dir
);
961 struct cgroup_subsys
*ss
;
963 for_each_subsys(cgrp
->root
, ss
) {
964 struct cftype_set
*set
;
965 if (!test_bit(ss
->subsys_id
, &subsys_mask
))
967 list_for_each_entry(set
, &ss
->cftsets
, node
)
968 cgroup_addrm_files(cgrp
, NULL
, set
->cfts
, false);
971 while (!list_empty(&cgrp
->files
))
972 cgroup_rm_file(cgrp
, NULL
);
977 * NOTE : the dentry must have been dget()'ed
979 static void cgroup_d_remove_dir(struct dentry
*dentry
)
981 struct dentry
*parent
;
982 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
984 cgroup_clear_directory(dentry
, true, root
->subsys_mask
);
986 parent
= dentry
->d_parent
;
987 spin_lock(&parent
->d_lock
);
988 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
989 list_del_init(&dentry
->d_u
.d_child
);
990 spin_unlock(&dentry
->d_lock
);
991 spin_unlock(&parent
->d_lock
);
996 * Call with cgroup_mutex held. Drops reference counts on modules, including
997 * any duplicate ones that parse_cgroupfs_options took. If this function
998 * returns an error, no reference counts are touched.
1000 static int rebind_subsystems(struct cgroupfs_root
*root
,
1001 unsigned long final_subsys_mask
)
1003 unsigned long added_mask
, removed_mask
;
1004 struct cgroup
*cgrp
= &root
->top_cgroup
;
1007 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
1008 BUG_ON(!mutex_is_locked(&cgroup_root_mutex
));
1010 removed_mask
= root
->actual_subsys_mask
& ~final_subsys_mask
;
1011 added_mask
= final_subsys_mask
& ~root
->actual_subsys_mask
;
1012 /* Check that any added subsystems are currently free */
1013 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1014 unsigned long bit
= 1UL << i
;
1015 struct cgroup_subsys
*ss
= subsys
[i
];
1016 if (!(bit
& added_mask
))
1019 * Nobody should tell us to do a subsys that doesn't exist:
1020 * parse_cgroupfs_options should catch that case and refcounts
1021 * ensure that subsystems won't disappear once selected.
1024 if (ss
->root
!= &rootnode
) {
1025 /* Subsystem isn't free */
1030 /* Currently we don't handle adding/removing subsystems when
1031 * any child cgroups exist. This is theoretically supportable
1032 * but involves complex error handling, so it's being left until
1034 if (root
->number_of_cgroups
> 1)
1037 /* Process each subsystem */
1038 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1039 struct cgroup_subsys
*ss
= subsys
[i
];
1040 unsigned long bit
= 1UL << i
;
1041 if (bit
& added_mask
) {
1042 /* We're binding this subsystem to this hierarchy */
1044 BUG_ON(cgrp
->subsys
[i
]);
1045 BUG_ON(!dummytop
->subsys
[i
]);
1046 BUG_ON(dummytop
->subsys
[i
]->cgroup
!= dummytop
);
1047 cgrp
->subsys
[i
] = dummytop
->subsys
[i
];
1048 cgrp
->subsys
[i
]->cgroup
= cgrp
;
1049 list_move(&ss
->sibling
, &root
->subsys_list
);
1053 /* refcount was already taken, and we're keeping it */
1054 } else if (bit
& removed_mask
) {
1055 /* We're removing this subsystem */
1057 BUG_ON(cgrp
->subsys
[i
] != dummytop
->subsys
[i
]);
1058 BUG_ON(cgrp
->subsys
[i
]->cgroup
!= cgrp
);
1061 dummytop
->subsys
[i
]->cgroup
= dummytop
;
1062 cgrp
->subsys
[i
] = NULL
;
1063 subsys
[i
]->root
= &rootnode
;
1064 list_move(&ss
->sibling
, &rootnode
.subsys_list
);
1065 /* subsystem is now free - drop reference on module */
1066 module_put(ss
->module
);
1067 } else if (bit
& final_subsys_mask
) {
1068 /* Subsystem state should already exist */
1070 BUG_ON(!cgrp
->subsys
[i
]);
1072 * a refcount was taken, but we already had one, so
1073 * drop the extra reference.
1075 module_put(ss
->module
);
1076 #ifdef CONFIG_MODULE_UNLOAD
1077 BUG_ON(ss
->module
&& !module_refcount(ss
->module
));
1080 /* Subsystem state shouldn't exist */
1081 BUG_ON(cgrp
->subsys
[i
]);
1084 root
->subsys_mask
= root
->actual_subsys_mask
= final_subsys_mask
;
1089 static int cgroup_show_options(struct seq_file
*seq
, struct dentry
*dentry
)
1091 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
1092 struct cgroup_subsys
*ss
;
1094 mutex_lock(&cgroup_root_mutex
);
1095 for_each_subsys(root
, ss
)
1096 seq_printf(seq
, ",%s", ss
->name
);
1097 if (root
->flags
& CGRP_ROOT_SANE_BEHAVIOR
)
1098 seq_puts(seq
, ",sane_behavior");
1099 if (root
->flags
& CGRP_ROOT_NOPREFIX
)
1100 seq_puts(seq
, ",noprefix");
1101 if (root
->flags
& CGRP_ROOT_XATTR
)
1102 seq_puts(seq
, ",xattr");
1103 if (strlen(root
->release_agent_path
))
1104 seq_printf(seq
, ",release_agent=%s", root
->release_agent_path
);
1105 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
))
1106 seq_puts(seq
, ",clone_children");
1107 if (strlen(root
->name
))
1108 seq_printf(seq
, ",name=%s", root
->name
);
1109 mutex_unlock(&cgroup_root_mutex
);
1113 struct cgroup_sb_opts
{
1114 unsigned long subsys_mask
;
1115 unsigned long flags
;
1116 char *release_agent
;
1117 bool cpuset_clone_children
;
1119 /* User explicitly requested empty subsystem */
1122 struct cgroupfs_root
*new_root
;
1127 * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call
1128 * with cgroup_mutex held to protect the subsys[] array. This function takes
1129 * refcounts on subsystems to be used, unless it returns error, in which case
1130 * no refcounts are taken.
1132 static int parse_cgroupfs_options(char *data
, struct cgroup_sb_opts
*opts
)
1134 char *token
, *o
= data
;
1135 bool all_ss
= false, one_ss
= false;
1136 unsigned long mask
= (unsigned long)-1;
1138 bool module_pin_failed
= false;
1140 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
1142 #ifdef CONFIG_CPUSETS
1143 mask
= ~(1UL << cpuset_subsys_id
);
1146 memset(opts
, 0, sizeof(*opts
));
1148 while ((token
= strsep(&o
, ",")) != NULL
) {
1151 if (!strcmp(token
, "none")) {
1152 /* Explicitly have no subsystems */
1156 if (!strcmp(token
, "all")) {
1157 /* Mutually exclusive option 'all' + subsystem name */
1163 if (!strcmp(token
, "__DEVEL__sane_behavior")) {
1164 opts
->flags
|= CGRP_ROOT_SANE_BEHAVIOR
;
1167 if (!strcmp(token
, "noprefix")) {
1168 opts
->flags
|= CGRP_ROOT_NOPREFIX
;
1171 if (!strcmp(token
, "clone_children")) {
1172 opts
->cpuset_clone_children
= true;
1175 if (!strcmp(token
, "xattr")) {
1176 opts
->flags
|= CGRP_ROOT_XATTR
;
1179 if (!strncmp(token
, "release_agent=", 14)) {
1180 /* Specifying two release agents is forbidden */
1181 if (opts
->release_agent
)
1183 opts
->release_agent
=
1184 kstrndup(token
+ 14, PATH_MAX
- 1, GFP_KERNEL
);
1185 if (!opts
->release_agent
)
1189 if (!strncmp(token
, "name=", 5)) {
1190 const char *name
= token
+ 5;
1191 /* Can't specify an empty name */
1194 /* Must match [\w.-]+ */
1195 for (i
= 0; i
< strlen(name
); i
++) {
1199 if ((c
== '.') || (c
== '-') || (c
== '_'))
1203 /* Specifying two names is forbidden */
1206 opts
->name
= kstrndup(name
,
1207 MAX_CGROUP_ROOT_NAMELEN
- 1,
1215 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1216 struct cgroup_subsys
*ss
= subsys
[i
];
1219 if (strcmp(token
, ss
->name
))
1224 /* Mutually exclusive option 'all' + subsystem name */
1227 set_bit(i
, &opts
->subsys_mask
);
1232 if (i
== CGROUP_SUBSYS_COUNT
)
1237 * If the 'all' option was specified select all the subsystems,
1238 * otherwise if 'none', 'name=' and a subsystem name options
1239 * were not specified, let's default to 'all'
1241 if (all_ss
|| (!one_ss
&& !opts
->none
&& !opts
->name
)) {
1242 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1243 struct cgroup_subsys
*ss
= subsys
[i
];
1248 set_bit(i
, &opts
->subsys_mask
);
1252 /* Consistency checks */
1254 if (opts
->flags
& CGRP_ROOT_SANE_BEHAVIOR
) {
1255 pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
1257 if (opts
->flags
& CGRP_ROOT_NOPREFIX
) {
1258 pr_err("cgroup: sane_behavior: noprefix is not allowed\n");
1262 if (opts
->cpuset_clone_children
) {
1263 pr_err("cgroup: sane_behavior: clone_children is not allowed\n");
1269 * Option noprefix was introduced just for backward compatibility
1270 * with the old cpuset, so we allow noprefix only if mounting just
1271 * the cpuset subsystem.
1273 if ((opts
->flags
& CGRP_ROOT_NOPREFIX
) && (opts
->subsys_mask
& mask
))
1277 /* Can't specify "none" and some subsystems */
1278 if (opts
->subsys_mask
&& opts
->none
)
1282 * We either have to specify by name or by subsystems. (So all
1283 * empty hierarchies must have a name).
1285 if (!opts
->subsys_mask
&& !opts
->name
)
1289 * Grab references on all the modules we'll need, so the subsystems
1290 * don't dance around before rebind_subsystems attaches them. This may
1291 * take duplicate reference counts on a subsystem that's already used,
1292 * but rebind_subsystems handles this case.
1294 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1295 unsigned long bit
= 1UL << i
;
1297 if (!(bit
& opts
->subsys_mask
))
1299 if (!try_module_get(subsys
[i
]->module
)) {
1300 module_pin_failed
= true;
1304 if (module_pin_failed
) {
1306 * oops, one of the modules was going away. this means that we
1307 * raced with a module_delete call, and to the user this is
1308 * essentially a "subsystem doesn't exist" case.
1310 for (i
--; i
>= 0; i
--) {
1311 /* drop refcounts only on the ones we took */
1312 unsigned long bit
= 1UL << i
;
1314 if (!(bit
& opts
->subsys_mask
))
1316 module_put(subsys
[i
]->module
);
1324 static void drop_parsed_module_refcounts(unsigned long subsys_mask
)
1327 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1328 unsigned long bit
= 1UL << i
;
1330 if (!(bit
& subsys_mask
))
1332 module_put(subsys
[i
]->module
);
1336 static int cgroup_remount(struct super_block
*sb
, int *flags
, char *data
)
1339 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1340 struct cgroup
*cgrp
= &root
->top_cgroup
;
1341 struct cgroup_sb_opts opts
;
1342 unsigned long added_mask
, removed_mask
;
1344 if (root
->flags
& CGRP_ROOT_SANE_BEHAVIOR
) {
1345 pr_err("cgroup: sane_behavior: remount is not allowed\n");
1349 mutex_lock(&cgrp
->dentry
->d_inode
->i_mutex
);
1350 mutex_lock(&cgroup_mutex
);
1351 mutex_lock(&cgroup_root_mutex
);
1353 /* See what subsystems are wanted */
1354 ret
= parse_cgroupfs_options(data
, &opts
);
1358 if (opts
.subsys_mask
!= root
->actual_subsys_mask
|| opts
.release_agent
)
1359 pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
1360 task_tgid_nr(current
), current
->comm
);
1362 added_mask
= opts
.subsys_mask
& ~root
->subsys_mask
;
1363 removed_mask
= root
->subsys_mask
& ~opts
.subsys_mask
;
1365 /* Don't allow flags or name to change at remount */
1366 if (opts
.flags
!= root
->flags
||
1367 (opts
.name
&& strcmp(opts
.name
, root
->name
))) {
1369 drop_parsed_module_refcounts(opts
.subsys_mask
);
1374 * Clear out the files of subsystems that should be removed, do
1375 * this before rebind_subsystems, since rebind_subsystems may
1376 * change this hierarchy's subsys_list.
1378 cgroup_clear_directory(cgrp
->dentry
, false, removed_mask
);
1380 ret
= rebind_subsystems(root
, opts
.subsys_mask
);
1382 /* rebind_subsystems failed, re-populate the removed files */
1383 cgroup_populate_dir(cgrp
, false, removed_mask
);
1384 drop_parsed_module_refcounts(opts
.subsys_mask
);
1388 /* re-populate subsystem files */
1389 cgroup_populate_dir(cgrp
, false, added_mask
);
1391 if (opts
.release_agent
)
1392 strcpy(root
->release_agent_path
, opts
.release_agent
);
1394 kfree(opts
.release_agent
);
1396 mutex_unlock(&cgroup_root_mutex
);
1397 mutex_unlock(&cgroup_mutex
);
1398 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
1402 static const struct super_operations cgroup_ops
= {
1403 .statfs
= simple_statfs
,
1404 .drop_inode
= generic_delete_inode
,
1405 .show_options
= cgroup_show_options
,
1406 .remount_fs
= cgroup_remount
,
1409 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1411 INIT_LIST_HEAD(&cgrp
->sibling
);
1412 INIT_LIST_HEAD(&cgrp
->children
);
1413 INIT_LIST_HEAD(&cgrp
->files
);
1414 INIT_LIST_HEAD(&cgrp
->cset_links
);
1415 INIT_LIST_HEAD(&cgrp
->allcg_node
);
1416 INIT_LIST_HEAD(&cgrp
->release_list
);
1417 INIT_LIST_HEAD(&cgrp
->pidlists
);
1418 INIT_WORK(&cgrp
->free_work
, cgroup_free_fn
);
1419 mutex_init(&cgrp
->pidlist_mutex
);
1420 INIT_LIST_HEAD(&cgrp
->event_list
);
1421 spin_lock_init(&cgrp
->event_list_lock
);
1422 simple_xattrs_init(&cgrp
->xattrs
);
1425 static void init_cgroup_root(struct cgroupfs_root
*root
)
1427 struct cgroup
*cgrp
= &root
->top_cgroup
;
1429 INIT_LIST_HEAD(&root
->subsys_list
);
1430 INIT_LIST_HEAD(&root
->root_list
);
1431 INIT_LIST_HEAD(&root
->allcg_list
);
1432 root
->number_of_cgroups
= 1;
1434 cgrp
->name
= &root_cgroup_name
;
1435 init_cgroup_housekeeping(cgrp
);
1436 list_add_tail(&cgrp
->allcg_node
, &root
->allcg_list
);
1439 static int cgroup_init_root_id(struct cgroupfs_root
*root
)
1443 lockdep_assert_held(&cgroup_mutex
);
1444 lockdep_assert_held(&cgroup_root_mutex
);
1446 id
= idr_alloc_cyclic(&cgroup_hierarchy_idr
, root
, 2, 0, GFP_KERNEL
);
1450 root
->hierarchy_id
= id
;
1454 static void cgroup_exit_root_id(struct cgroupfs_root
*root
)
1456 lockdep_assert_held(&cgroup_mutex
);
1457 lockdep_assert_held(&cgroup_root_mutex
);
1459 if (root
->hierarchy_id
) {
1460 idr_remove(&cgroup_hierarchy_idr
, root
->hierarchy_id
);
1461 root
->hierarchy_id
= 0;
1465 static int cgroup_test_super(struct super_block
*sb
, void *data
)
1467 struct cgroup_sb_opts
*opts
= data
;
1468 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1470 /* If we asked for a name then it must match */
1471 if (opts
->name
&& strcmp(opts
->name
, root
->name
))
1475 * If we asked for subsystems (or explicitly for no
1476 * subsystems) then they must match
1478 if ((opts
->subsys_mask
|| opts
->none
)
1479 && (opts
->subsys_mask
!= root
->subsys_mask
))
1485 static struct cgroupfs_root
*cgroup_root_from_opts(struct cgroup_sb_opts
*opts
)
1487 struct cgroupfs_root
*root
;
1489 if (!opts
->subsys_mask
&& !opts
->none
)
1492 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
1494 return ERR_PTR(-ENOMEM
);
1496 init_cgroup_root(root
);
1498 root
->subsys_mask
= opts
->subsys_mask
;
1499 root
->flags
= opts
->flags
;
1500 ida_init(&root
->cgroup_ida
);
1501 if (opts
->release_agent
)
1502 strcpy(root
->release_agent_path
, opts
->release_agent
);
1504 strcpy(root
->name
, opts
->name
);
1505 if (opts
->cpuset_clone_children
)
1506 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
);
1510 static void cgroup_free_root(struct cgroupfs_root
*root
)
1513 /* hierarhcy ID shoulid already have been released */
1514 WARN_ON_ONCE(root
->hierarchy_id
);
1516 ida_destroy(&root
->cgroup_ida
);
1521 static int cgroup_set_super(struct super_block
*sb
, void *data
)
1524 struct cgroup_sb_opts
*opts
= data
;
1526 /* If we don't have a new root, we can't set up a new sb */
1527 if (!opts
->new_root
)
1530 BUG_ON(!opts
->subsys_mask
&& !opts
->none
);
1532 ret
= set_anon_super(sb
, NULL
);
1536 sb
->s_fs_info
= opts
->new_root
;
1537 opts
->new_root
->sb
= sb
;
1539 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
1540 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
1541 sb
->s_magic
= CGROUP_SUPER_MAGIC
;
1542 sb
->s_op
= &cgroup_ops
;
1547 static int cgroup_get_rootdir(struct super_block
*sb
)
1549 static const struct dentry_operations cgroup_dops
= {
1550 .d_iput
= cgroup_diput
,
1551 .d_delete
= cgroup_delete
,
1554 struct inode
*inode
=
1555 cgroup_new_inode(S_IFDIR
| S_IRUGO
| S_IXUGO
| S_IWUSR
, sb
);
1560 inode
->i_fop
= &simple_dir_operations
;
1561 inode
->i_op
= &cgroup_dir_inode_operations
;
1562 /* directories start off with i_nlink == 2 (for "." entry) */
1564 sb
->s_root
= d_make_root(inode
);
1567 /* for everything else we want ->d_op set */
1568 sb
->s_d_op
= &cgroup_dops
;
1572 static struct dentry
*cgroup_mount(struct file_system_type
*fs_type
,
1573 int flags
, const char *unused_dev_name
,
1576 struct cgroup_sb_opts opts
;
1577 struct cgroupfs_root
*root
;
1579 struct super_block
*sb
;
1580 struct cgroupfs_root
*new_root
;
1581 struct inode
*inode
;
1583 /* First find the desired set of subsystems */
1584 mutex_lock(&cgroup_mutex
);
1585 ret
= parse_cgroupfs_options(data
, &opts
);
1586 mutex_unlock(&cgroup_mutex
);
1591 * Allocate a new cgroup root. We may not need it if we're
1592 * reusing an existing hierarchy.
1594 new_root
= cgroup_root_from_opts(&opts
);
1595 if (IS_ERR(new_root
)) {
1596 ret
= PTR_ERR(new_root
);
1599 opts
.new_root
= new_root
;
1601 /* Locate an existing or new sb for this hierarchy */
1602 sb
= sget(fs_type
, cgroup_test_super
, cgroup_set_super
, 0, &opts
);
1605 cgroup_free_root(opts
.new_root
);
1609 root
= sb
->s_fs_info
;
1611 if (root
== opts
.new_root
) {
1612 /* We used the new root structure, so this is a new hierarchy */
1613 struct list_head tmp_links
;
1614 struct cgroup
*root_cgrp
= &root
->top_cgroup
;
1615 struct cgroupfs_root
*existing_root
;
1616 const struct cred
*cred
;
1618 struct css_set
*cset
;
1620 BUG_ON(sb
->s_root
!= NULL
);
1622 ret
= cgroup_get_rootdir(sb
);
1624 goto drop_new_super
;
1625 inode
= sb
->s_root
->d_inode
;
1627 mutex_lock(&inode
->i_mutex
);
1628 mutex_lock(&cgroup_mutex
);
1629 mutex_lock(&cgroup_root_mutex
);
1631 /* Check for name clashes with existing mounts */
1633 if (strlen(root
->name
))
1634 for_each_active_root(existing_root
)
1635 if (!strcmp(existing_root
->name
, root
->name
))
1639 * We're accessing css_set_count without locking
1640 * css_set_lock here, but that's OK - it can only be
1641 * increased by someone holding cgroup_lock, and
1642 * that's us. The worst that can happen is that we
1643 * have some link structures left over
1645 ret
= allocate_cgrp_cset_links(css_set_count
, &tmp_links
);
1649 ret
= cgroup_init_root_id(root
);
1653 ret
= rebind_subsystems(root
, root
->subsys_mask
);
1654 if (ret
== -EBUSY
) {
1655 free_cgrp_cset_links(&tmp_links
);
1659 * There must be no failure case after here, since rebinding
1660 * takes care of subsystems' refcounts, which are explicitly
1661 * dropped in the failure exit path.
1664 /* EBUSY should be the only error here */
1667 list_add(&root
->root_list
, &roots
);
1670 sb
->s_root
->d_fsdata
= root_cgrp
;
1671 root
->top_cgroup
.dentry
= sb
->s_root
;
1673 /* Link the top cgroup in this hierarchy into all
1674 * the css_set objects */
1675 write_lock(&css_set_lock
);
1676 hash_for_each(css_set_table
, i
, cset
, hlist
)
1677 link_css_set(&tmp_links
, cset
, root_cgrp
);
1678 write_unlock(&css_set_lock
);
1680 free_cgrp_cset_links(&tmp_links
);
1682 BUG_ON(!list_empty(&root_cgrp
->children
));
1683 BUG_ON(root
->number_of_cgroups
!= 1);
1685 cred
= override_creds(&init_cred
);
1686 cgroup_populate_dir(root_cgrp
, true, root
->subsys_mask
);
1688 mutex_unlock(&cgroup_root_mutex
);
1689 mutex_unlock(&cgroup_mutex
);
1690 mutex_unlock(&inode
->i_mutex
);
1693 * We re-used an existing hierarchy - the new root (if
1694 * any) is not needed
1696 cgroup_free_root(opts
.new_root
);
1698 if (((root
->flags
| opts
.flags
) & CGRP_ROOT_SANE_BEHAVIOR
) &&
1699 root
->flags
!= opts
.flags
) {
1700 pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
1702 goto drop_new_super
;
1705 /* no subsys rebinding, so refcounts don't change */
1706 drop_parsed_module_refcounts(opts
.subsys_mask
);
1709 kfree(opts
.release_agent
);
1711 return dget(sb
->s_root
);
1714 cgroup_exit_root_id(root
);
1715 mutex_unlock(&cgroup_root_mutex
);
1716 mutex_unlock(&cgroup_mutex
);
1717 mutex_unlock(&inode
->i_mutex
);
1719 deactivate_locked_super(sb
);
1721 drop_parsed_module_refcounts(opts
.subsys_mask
);
1723 kfree(opts
.release_agent
);
1725 return ERR_PTR(ret
);
1728 static void cgroup_kill_sb(struct super_block
*sb
) {
1729 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1730 struct cgroup
*cgrp
= &root
->top_cgroup
;
1731 struct cgrp_cset_link
*link
, *tmp_link
;
1736 BUG_ON(root
->number_of_cgroups
!= 1);
1737 BUG_ON(!list_empty(&cgrp
->children
));
1739 mutex_lock(&cgroup_mutex
);
1740 mutex_lock(&cgroup_root_mutex
);
1742 /* Rebind all subsystems back to the default hierarchy */
1743 ret
= rebind_subsystems(root
, 0);
1744 /* Shouldn't be able to fail ... */
1748 * Release all the links from cset_links to this hierarchy's
1751 write_lock(&css_set_lock
);
1753 list_for_each_entry_safe(link
, tmp_link
, &cgrp
->cset_links
, cset_link
) {
1754 list_del(&link
->cset_link
);
1755 list_del(&link
->cgrp_link
);
1758 write_unlock(&css_set_lock
);
1760 if (!list_empty(&root
->root_list
)) {
1761 list_del(&root
->root_list
);
1765 cgroup_exit_root_id(root
);
1767 mutex_unlock(&cgroup_root_mutex
);
1768 mutex_unlock(&cgroup_mutex
);
1770 simple_xattrs_free(&cgrp
->xattrs
);
1772 kill_litter_super(sb
);
1773 cgroup_free_root(root
);
1776 static struct file_system_type cgroup_fs_type
= {
1778 .mount
= cgroup_mount
,
1779 .kill_sb
= cgroup_kill_sb
,
1782 static struct kobject
*cgroup_kobj
;
1785 * cgroup_path - generate the path of a cgroup
1786 * @cgrp: the cgroup in question
1787 * @buf: the buffer to write the path into
1788 * @buflen: the length of the buffer
1790 * Writes path of cgroup into buf. Returns 0 on success, -errno on error.
1792 * We can't generate cgroup path using dentry->d_name, as accessing
1793 * dentry->name must be protected by irq-unsafe dentry->d_lock or parent
1794 * inode's i_mutex, while on the other hand cgroup_path() can be called
1795 * with some irq-safe spinlocks held.
1797 int cgroup_path(const struct cgroup
*cgrp
, char *buf
, int buflen
)
1799 int ret
= -ENAMETOOLONG
;
1802 if (!cgrp
->parent
) {
1803 if (strlcpy(buf
, "/", buflen
) >= buflen
)
1804 return -ENAMETOOLONG
;
1808 start
= buf
+ buflen
- 1;
1813 const char *name
= cgroup_name(cgrp
);
1817 if ((start
-= len
) < buf
)
1819 memcpy(start
, name
, len
);
1825 cgrp
= cgrp
->parent
;
1826 } while (cgrp
->parent
);
1828 memmove(buf
, start
, buf
+ buflen
- start
);
1833 EXPORT_SYMBOL_GPL(cgroup_path
);
1836 * task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy
1837 * @task: target task
1838 * @hierarchy_id: the hierarchy to look up @task's cgroup from
1839 * @buf: the buffer to write the path into
1840 * @buflen: the length of the buffer
1842 * Determine @task's cgroup on the hierarchy specified by @hierarchy_id and
1843 * copy its path into @buf. This function grabs cgroup_mutex and shouldn't
1844 * be used inside locks used by cgroup controller callbacks.
1846 int task_cgroup_path_from_hierarchy(struct task_struct
*task
, int hierarchy_id
,
1847 char *buf
, size_t buflen
)
1849 struct cgroupfs_root
*root
;
1850 struct cgroup
*cgrp
= NULL
;
1853 mutex_lock(&cgroup_mutex
);
1855 root
= idr_find(&cgroup_hierarchy_idr
, hierarchy_id
);
1857 cgrp
= task_cgroup_from_root(task
, root
);
1858 ret
= cgroup_path(cgrp
, buf
, buflen
);
1861 mutex_unlock(&cgroup_mutex
);
1865 EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy
);
1868 * Control Group taskset
1870 struct task_and_cgroup
{
1871 struct task_struct
*task
;
1872 struct cgroup
*cgrp
;
1876 struct cgroup_taskset
{
1877 struct task_and_cgroup single
;
1878 struct flex_array
*tc_array
;
1881 struct cgroup
*cur_cgrp
;
1885 * cgroup_taskset_first - reset taskset and return the first task
1886 * @tset: taskset of interest
1888 * @tset iteration is initialized and the first task is returned.
1890 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
)
1892 if (tset
->tc_array
) {
1894 return cgroup_taskset_next(tset
);
1896 tset
->cur_cgrp
= tset
->single
.cgrp
;
1897 return tset
->single
.task
;
1900 EXPORT_SYMBOL_GPL(cgroup_taskset_first
);
1903 * cgroup_taskset_next - iterate to the next task in taskset
1904 * @tset: taskset of interest
1906 * Return the next task in @tset. Iteration must have been initialized
1907 * with cgroup_taskset_first().
1909 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
)
1911 struct task_and_cgroup
*tc
;
1913 if (!tset
->tc_array
|| tset
->idx
>= tset
->tc_array_len
)
1916 tc
= flex_array_get(tset
->tc_array
, tset
->idx
++);
1917 tset
->cur_cgrp
= tc
->cgrp
;
1920 EXPORT_SYMBOL_GPL(cgroup_taskset_next
);
1923 * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task
1924 * @tset: taskset of interest
1926 * Return the cgroup for the current (last returned) task of @tset. This
1927 * function must be preceded by either cgroup_taskset_first() or
1928 * cgroup_taskset_next().
1930 struct cgroup
*cgroup_taskset_cur_cgroup(struct cgroup_taskset
*tset
)
1932 return tset
->cur_cgrp
;
1934 EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup
);
1937 * cgroup_taskset_size - return the number of tasks in taskset
1938 * @tset: taskset of interest
1940 int cgroup_taskset_size(struct cgroup_taskset
*tset
)
1942 return tset
->tc_array
? tset
->tc_array_len
: 1;
1944 EXPORT_SYMBOL_GPL(cgroup_taskset_size
);
1948 * cgroup_task_migrate - move a task from one cgroup to another.
1950 * Must be called with cgroup_mutex and threadgroup locked.
1952 static void cgroup_task_migrate(struct cgroup
*old_cgrp
,
1953 struct task_struct
*tsk
,
1954 struct css_set
*new_cset
)
1956 struct css_set
*old_cset
;
1959 * We are synchronized through threadgroup_lock() against PF_EXITING
1960 * setting such that we can't race against cgroup_exit() changing the
1961 * css_set to init_css_set and dropping the old one.
1963 WARN_ON_ONCE(tsk
->flags
& PF_EXITING
);
1964 old_cset
= tsk
->cgroups
;
1967 rcu_assign_pointer(tsk
->cgroups
, new_cset
);
1970 /* Update the css_set linked lists if we're using them */
1971 write_lock(&css_set_lock
);
1972 if (!list_empty(&tsk
->cg_list
))
1973 list_move(&tsk
->cg_list
, &new_cset
->tasks
);
1974 write_unlock(&css_set_lock
);
1977 * We just gained a reference on old_cset by taking it from the
1978 * task. As trading it for new_cset is protected by cgroup_mutex,
1979 * we're safe to drop it here; it will be freed under RCU.
1981 set_bit(CGRP_RELEASABLE
, &old_cgrp
->flags
);
1982 put_css_set(old_cset
);
1986 * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
1987 * @cgrp: the cgroup to attach to
1988 * @tsk: the task or the leader of the threadgroup to be attached
1989 * @threadgroup: attach the whole threadgroup?
1991 * Call holding cgroup_mutex and the group_rwsem of the leader. Will take
1992 * task_lock of @tsk or each thread in the threadgroup individually in turn.
1994 static int cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
,
1997 int retval
, i
, group_size
;
1998 struct cgroup_subsys
*ss
, *failed_ss
= NULL
;
1999 struct cgroupfs_root
*root
= cgrp
->root
;
2000 /* threadgroup list cursor and array */
2001 struct task_struct
*leader
= tsk
;
2002 struct task_and_cgroup
*tc
;
2003 struct flex_array
*group
;
2004 struct cgroup_taskset tset
= { };
2007 * step 0: in order to do expensive, possibly blocking operations for
2008 * every thread, we cannot iterate the thread group list, since it needs
2009 * rcu or tasklist locked. instead, build an array of all threads in the
2010 * group - group_rwsem prevents new threads from appearing, and if
2011 * threads exit, this will just be an over-estimate.
2014 group_size
= get_nr_threads(tsk
);
2017 /* flex_array supports very large thread-groups better than kmalloc. */
2018 group
= flex_array_alloc(sizeof(*tc
), group_size
, GFP_KERNEL
);
2021 /* pre-allocate to guarantee space while iterating in rcu read-side. */
2022 retval
= flex_array_prealloc(group
, 0, group_size
, GFP_KERNEL
);
2024 goto out_free_group_list
;
2028 * Prevent freeing of tasks while we take a snapshot. Tasks that are
2029 * already PF_EXITING could be freed from underneath us unless we
2030 * take an rcu_read_lock.
2034 struct task_and_cgroup ent
;
2036 /* @tsk either already exited or can't exit until the end */
2037 if (tsk
->flags
& PF_EXITING
)
2040 /* as per above, nr_threads may decrease, but not increase. */
2041 BUG_ON(i
>= group_size
);
2043 ent
.cgrp
= task_cgroup_from_root(tsk
, root
);
2044 /* nothing to do if this task is already in the cgroup */
2045 if (ent
.cgrp
== cgrp
)
2048 * saying GFP_ATOMIC has no effect here because we did prealloc
2049 * earlier, but it's good form to communicate our expectations.
2051 retval
= flex_array_put(group
, i
, &ent
, GFP_ATOMIC
);
2052 BUG_ON(retval
!= 0);
2057 } while_each_thread(leader
, tsk
);
2059 /* remember the number of threads in the array for later. */
2061 tset
.tc_array
= group
;
2062 tset
.tc_array_len
= group_size
;
2064 /* methods shouldn't be called if no task is actually migrating */
2067 goto out_free_group_list
;
2070 * step 1: check that we can legitimately attach to the cgroup.
2072 for_each_subsys(root
, ss
) {
2073 if (ss
->can_attach
) {
2074 retval
= ss
->can_attach(cgrp
, &tset
);
2077 goto out_cancel_attach
;
2083 * step 2: make sure css_sets exist for all threads to be migrated.
2084 * we use find_css_set, which allocates a new one if necessary.
2086 for (i
= 0; i
< group_size
; i
++) {
2087 tc
= flex_array_get(group
, i
);
2088 tc
->cg
= find_css_set(tc
->task
->cgroups
, cgrp
);
2091 goto out_put_css_set_refs
;
2096 * step 3: now that we're guaranteed success wrt the css_sets,
2097 * proceed to move all tasks to the new cgroup. There are no
2098 * failure cases after here, so this is the commit point.
2100 for (i
= 0; i
< group_size
; i
++) {
2101 tc
= flex_array_get(group
, i
);
2102 cgroup_task_migrate(tc
->cgrp
, tc
->task
, tc
->cg
);
2104 /* nothing is sensitive to fork() after this point. */
2107 * step 4: do subsystem attach callbacks.
2109 for_each_subsys(root
, ss
) {
2111 ss
->attach(cgrp
, &tset
);
2115 * step 5: success! and cleanup
2118 out_put_css_set_refs
:
2120 for (i
= 0; i
< group_size
; i
++) {
2121 tc
= flex_array_get(group
, i
);
2124 put_css_set(tc
->cg
);
2129 for_each_subsys(root
, ss
) {
2130 if (ss
== failed_ss
)
2132 if (ss
->cancel_attach
)
2133 ss
->cancel_attach(cgrp
, &tset
);
2136 out_free_group_list
:
2137 flex_array_free(group
);
2142 * Find the task_struct of the task to attach by vpid and pass it along to the
2143 * function to attach either it or all tasks in its threadgroup. Will lock
2144 * cgroup_mutex and threadgroup; may take task_lock of task.
2146 static int attach_task_by_pid(struct cgroup
*cgrp
, u64 pid
, bool threadgroup
)
2148 struct task_struct
*tsk
;
2149 const struct cred
*cred
= current_cred(), *tcred
;
2152 if (!cgroup_lock_live_group(cgrp
))
2158 tsk
= find_task_by_vpid(pid
);
2162 goto out_unlock_cgroup
;
2165 * even if we're attaching all tasks in the thread group, we
2166 * only need to check permissions on one of them.
2168 tcred
= __task_cred(tsk
);
2169 if (!uid_eq(cred
->euid
, GLOBAL_ROOT_UID
) &&
2170 !uid_eq(cred
->euid
, tcred
->uid
) &&
2171 !uid_eq(cred
->euid
, tcred
->suid
)) {
2174 goto out_unlock_cgroup
;
2180 tsk
= tsk
->group_leader
;
2183 * Workqueue threads may acquire PF_NO_SETAFFINITY and become
2184 * trapped in a cpuset, or RT worker may be born in a cgroup
2185 * with no rt_runtime allocated. Just say no.
2187 if (tsk
== kthreadd_task
|| (tsk
->flags
& PF_NO_SETAFFINITY
)) {
2190 goto out_unlock_cgroup
;
2193 get_task_struct(tsk
);
2196 threadgroup_lock(tsk
);
2198 if (!thread_group_leader(tsk
)) {
2200 * a race with de_thread from another thread's exec()
2201 * may strip us of our leadership, if this happens,
2202 * there is no choice but to throw this task away and
2203 * try again; this is
2204 * "double-double-toil-and-trouble-check locking".
2206 threadgroup_unlock(tsk
);
2207 put_task_struct(tsk
);
2208 goto retry_find_task
;
2212 ret
= cgroup_attach_task(cgrp
, tsk
, threadgroup
);
2214 threadgroup_unlock(tsk
);
2216 put_task_struct(tsk
);
2218 mutex_unlock(&cgroup_mutex
);
2223 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
2224 * @from: attach to all cgroups of a given task
2225 * @tsk: the task to be attached
2227 int cgroup_attach_task_all(struct task_struct
*from
, struct task_struct
*tsk
)
2229 struct cgroupfs_root
*root
;
2232 mutex_lock(&cgroup_mutex
);
2233 for_each_active_root(root
) {
2234 struct cgroup
*from_cg
= task_cgroup_from_root(from
, root
);
2236 retval
= cgroup_attach_task(from_cg
, tsk
, false);
2240 mutex_unlock(&cgroup_mutex
);
2244 EXPORT_SYMBOL_GPL(cgroup_attach_task_all
);
2246 static int cgroup_tasks_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 pid
)
2248 return attach_task_by_pid(cgrp
, pid
, false);
2251 static int cgroup_procs_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 tgid
)
2253 return attach_task_by_pid(cgrp
, tgid
, true);
2256 static int cgroup_release_agent_write(struct cgroup
*cgrp
, struct cftype
*cft
,
2259 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
2260 if (strlen(buffer
) >= PATH_MAX
)
2262 if (!cgroup_lock_live_group(cgrp
))
2264 mutex_lock(&cgroup_root_mutex
);
2265 strcpy(cgrp
->root
->release_agent_path
, buffer
);
2266 mutex_unlock(&cgroup_root_mutex
);
2267 mutex_unlock(&cgroup_mutex
);
2271 static int cgroup_release_agent_show(struct cgroup
*cgrp
, struct cftype
*cft
,
2272 struct seq_file
*seq
)
2274 if (!cgroup_lock_live_group(cgrp
))
2276 seq_puts(seq
, cgrp
->root
->release_agent_path
);
2277 seq_putc(seq
, '\n');
2278 mutex_unlock(&cgroup_mutex
);
2282 static int cgroup_sane_behavior_show(struct cgroup
*cgrp
, struct cftype
*cft
,
2283 struct seq_file
*seq
)
2285 seq_printf(seq
, "%d\n", cgroup_sane_behavior(cgrp
));
2289 /* A buffer size big enough for numbers or short strings */
2290 #define CGROUP_LOCAL_BUFFER_SIZE 64
2292 static ssize_t
cgroup_write_X64(struct cgroup
*cgrp
, struct cftype
*cft
,
2294 const char __user
*userbuf
,
2295 size_t nbytes
, loff_t
*unused_ppos
)
2297 char buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
2303 if (nbytes
>= sizeof(buffer
))
2305 if (copy_from_user(buffer
, userbuf
, nbytes
))
2308 buffer
[nbytes
] = 0; /* nul-terminate */
2309 if (cft
->write_u64
) {
2310 u64 val
= simple_strtoull(strstrip(buffer
), &end
, 0);
2313 retval
= cft
->write_u64(cgrp
, cft
, val
);
2315 s64 val
= simple_strtoll(strstrip(buffer
), &end
, 0);
2318 retval
= cft
->write_s64(cgrp
, cft
, val
);
2325 static ssize_t
cgroup_write_string(struct cgroup
*cgrp
, struct cftype
*cft
,
2327 const char __user
*userbuf
,
2328 size_t nbytes
, loff_t
*unused_ppos
)
2330 char local_buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
2332 size_t max_bytes
= cft
->max_write_len
;
2333 char *buffer
= local_buffer
;
2336 max_bytes
= sizeof(local_buffer
) - 1;
2337 if (nbytes
>= max_bytes
)
2339 /* Allocate a dynamic buffer if we need one */
2340 if (nbytes
>= sizeof(local_buffer
)) {
2341 buffer
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
2345 if (nbytes
&& copy_from_user(buffer
, userbuf
, nbytes
)) {
2350 buffer
[nbytes
] = 0; /* nul-terminate */
2351 retval
= cft
->write_string(cgrp
, cft
, strstrip(buffer
));
2355 if (buffer
!= local_buffer
)
2360 static ssize_t
cgroup_file_write(struct file
*file
, const char __user
*buf
,
2361 size_t nbytes
, loff_t
*ppos
)
2363 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2364 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2366 if (cgroup_is_removed(cgrp
))
2369 return cft
->write(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2370 if (cft
->write_u64
|| cft
->write_s64
)
2371 return cgroup_write_X64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2372 if (cft
->write_string
)
2373 return cgroup_write_string(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2375 int ret
= cft
->trigger(cgrp
, (unsigned int)cft
->private);
2376 return ret
? ret
: nbytes
;
2381 static ssize_t
cgroup_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
2383 char __user
*buf
, size_t nbytes
,
2386 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
2387 u64 val
= cft
->read_u64(cgrp
, cft
);
2388 int len
= sprintf(tmp
, "%llu\n", (unsigned long long) val
);
2390 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
2393 static ssize_t
cgroup_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
,
2395 char __user
*buf
, size_t nbytes
,
2398 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
2399 s64 val
= cft
->read_s64(cgrp
, cft
);
2400 int len
= sprintf(tmp
, "%lld\n", (long long) val
);
2402 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
2405 static ssize_t
cgroup_file_read(struct file
*file
, char __user
*buf
,
2406 size_t nbytes
, loff_t
*ppos
)
2408 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2409 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2411 if (cgroup_is_removed(cgrp
))
2415 return cft
->read(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2417 return cgroup_read_u64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2419 return cgroup_read_s64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2424 * seqfile ops/methods for returning structured data. Currently just
2425 * supports string->u64 maps, but can be extended in future.
2428 struct cgroup_seqfile_state
{
2430 struct cgroup
*cgroup
;
2433 static int cgroup_map_add(struct cgroup_map_cb
*cb
, const char *key
, u64 value
)
2435 struct seq_file
*sf
= cb
->state
;
2436 return seq_printf(sf
, "%s %llu\n", key
, (unsigned long long)value
);
2439 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
2441 struct cgroup_seqfile_state
*state
= m
->private;
2442 struct cftype
*cft
= state
->cft
;
2443 if (cft
->read_map
) {
2444 struct cgroup_map_cb cb
= {
2445 .fill
= cgroup_map_add
,
2448 return cft
->read_map(state
->cgroup
, cft
, &cb
);
2450 return cft
->read_seq_string(state
->cgroup
, cft
, m
);
2453 static int cgroup_seqfile_release(struct inode
*inode
, struct file
*file
)
2455 struct seq_file
*seq
= file
->private_data
;
2456 kfree(seq
->private);
2457 return single_release(inode
, file
);
2460 static const struct file_operations cgroup_seqfile_operations
= {
2462 .write
= cgroup_file_write
,
2463 .llseek
= seq_lseek
,
2464 .release
= cgroup_seqfile_release
,
2467 static int cgroup_file_open(struct inode
*inode
, struct file
*file
)
2472 err
= generic_file_open(inode
, file
);
2475 cft
= __d_cft(file
->f_dentry
);
2477 if (cft
->read_map
|| cft
->read_seq_string
) {
2478 struct cgroup_seqfile_state
*state
;
2480 state
= kzalloc(sizeof(*state
), GFP_USER
);
2485 state
->cgroup
= __d_cgrp(file
->f_dentry
->d_parent
);
2486 file
->f_op
= &cgroup_seqfile_operations
;
2487 err
= single_open(file
, cgroup_seqfile_show
, state
);
2490 } else if (cft
->open
)
2491 err
= cft
->open(inode
, file
);
2498 static int cgroup_file_release(struct inode
*inode
, struct file
*file
)
2500 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2502 return cft
->release(inode
, file
);
2507 * cgroup_rename - Only allow simple rename of directories in place.
2509 static int cgroup_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2510 struct inode
*new_dir
, struct dentry
*new_dentry
)
2513 struct cgroup_name
*name
, *old_name
;
2514 struct cgroup
*cgrp
;
2517 * It's convinient to use parent dir's i_mutex to protected
2520 lockdep_assert_held(&old_dir
->i_mutex
);
2522 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
))
2524 if (new_dentry
->d_inode
)
2526 if (old_dir
!= new_dir
)
2529 cgrp
= __d_cgrp(old_dentry
);
2531 name
= cgroup_alloc_name(new_dentry
);
2535 ret
= simple_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2541 old_name
= cgrp
->name
;
2542 rcu_assign_pointer(cgrp
->name
, name
);
2544 kfree_rcu(old_name
, rcu_head
);
2548 static struct simple_xattrs
*__d_xattrs(struct dentry
*dentry
)
2550 if (S_ISDIR(dentry
->d_inode
->i_mode
))
2551 return &__d_cgrp(dentry
)->xattrs
;
2553 return &__d_cfe(dentry
)->xattrs
;
2556 static inline int xattr_enabled(struct dentry
*dentry
)
2558 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
2559 return root
->flags
& CGRP_ROOT_XATTR
;
2562 static bool is_valid_xattr(const char *name
)
2564 if (!strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
) ||
2565 !strncmp(name
, XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
))
2570 static int cgroup_setxattr(struct dentry
*dentry
, const char *name
,
2571 const void *val
, size_t size
, int flags
)
2573 if (!xattr_enabled(dentry
))
2575 if (!is_valid_xattr(name
))
2577 return simple_xattr_set(__d_xattrs(dentry
), name
, val
, size
, flags
);
2580 static int cgroup_removexattr(struct dentry
*dentry
, const char *name
)
2582 if (!xattr_enabled(dentry
))
2584 if (!is_valid_xattr(name
))
2586 return simple_xattr_remove(__d_xattrs(dentry
), name
);
2589 static ssize_t
cgroup_getxattr(struct dentry
*dentry
, const char *name
,
2590 void *buf
, size_t size
)
2592 if (!xattr_enabled(dentry
))
2594 if (!is_valid_xattr(name
))
2596 return simple_xattr_get(__d_xattrs(dentry
), name
, buf
, size
);
2599 static ssize_t
cgroup_listxattr(struct dentry
*dentry
, char *buf
, size_t size
)
2601 if (!xattr_enabled(dentry
))
2603 return simple_xattr_list(__d_xattrs(dentry
), buf
, size
);
2606 static const struct file_operations cgroup_file_operations
= {
2607 .read
= cgroup_file_read
,
2608 .write
= cgroup_file_write
,
2609 .llseek
= generic_file_llseek
,
2610 .open
= cgroup_file_open
,
2611 .release
= cgroup_file_release
,
2614 static const struct inode_operations cgroup_file_inode_operations
= {
2615 .setxattr
= cgroup_setxattr
,
2616 .getxattr
= cgroup_getxattr
,
2617 .listxattr
= cgroup_listxattr
,
2618 .removexattr
= cgroup_removexattr
,
2621 static const struct inode_operations cgroup_dir_inode_operations
= {
2622 .lookup
= cgroup_lookup
,
2623 .mkdir
= cgroup_mkdir
,
2624 .rmdir
= cgroup_rmdir
,
2625 .rename
= cgroup_rename
,
2626 .setxattr
= cgroup_setxattr
,
2627 .getxattr
= cgroup_getxattr
,
2628 .listxattr
= cgroup_listxattr
,
2629 .removexattr
= cgroup_removexattr
,
2632 static struct dentry
*cgroup_lookup(struct inode
*dir
, struct dentry
*dentry
, unsigned int flags
)
2634 if (dentry
->d_name
.len
> NAME_MAX
)
2635 return ERR_PTR(-ENAMETOOLONG
);
2636 d_add(dentry
, NULL
);
2641 * Check if a file is a control file
2643 static inline struct cftype
*__file_cft(struct file
*file
)
2645 if (file_inode(file
)->i_fop
!= &cgroup_file_operations
)
2646 return ERR_PTR(-EINVAL
);
2647 return __d_cft(file
->f_dentry
);
2650 static int cgroup_create_file(struct dentry
*dentry
, umode_t mode
,
2651 struct super_block
*sb
)
2653 struct inode
*inode
;
2657 if (dentry
->d_inode
)
2660 inode
= cgroup_new_inode(mode
, sb
);
2664 if (S_ISDIR(mode
)) {
2665 inode
->i_op
= &cgroup_dir_inode_operations
;
2666 inode
->i_fop
= &simple_dir_operations
;
2668 /* start off with i_nlink == 2 (for "." entry) */
2670 inc_nlink(dentry
->d_parent
->d_inode
);
2673 * Control reaches here with cgroup_mutex held.
2674 * @inode->i_mutex should nest outside cgroup_mutex but we
2675 * want to populate it immediately without releasing
2676 * cgroup_mutex. As @inode isn't visible to anyone else
2677 * yet, trylock will always succeed without affecting
2680 WARN_ON_ONCE(!mutex_trylock(&inode
->i_mutex
));
2681 } else if (S_ISREG(mode
)) {
2683 inode
->i_fop
= &cgroup_file_operations
;
2684 inode
->i_op
= &cgroup_file_inode_operations
;
2686 d_instantiate(dentry
, inode
);
2687 dget(dentry
); /* Extra count - pin the dentry in core */
2692 * cgroup_file_mode - deduce file mode of a control file
2693 * @cft: the control file in question
2695 * returns cft->mode if ->mode is not 0
2696 * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
2697 * returns S_IRUGO if it has only a read handler
2698 * returns S_IWUSR if it has only a write hander
2700 static umode_t
cgroup_file_mode(const struct cftype
*cft
)
2707 if (cft
->read
|| cft
->read_u64
|| cft
->read_s64
||
2708 cft
->read_map
|| cft
->read_seq_string
)
2711 if (cft
->write
|| cft
->write_u64
|| cft
->write_s64
||
2712 cft
->write_string
|| cft
->trigger
)
2718 static int cgroup_add_file(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
2721 struct dentry
*dir
= cgrp
->dentry
;
2722 struct cgroup
*parent
= __d_cgrp(dir
);
2723 struct dentry
*dentry
;
2727 char name
[MAX_CGROUP_TYPE_NAMELEN
+ MAX_CFTYPE_NAME
+ 2] = { 0 };
2729 if (subsys
&& !(cgrp
->root
->flags
& CGRP_ROOT_NOPREFIX
)) {
2730 strcpy(name
, subsys
->name
);
2733 strcat(name
, cft
->name
);
2735 BUG_ON(!mutex_is_locked(&dir
->d_inode
->i_mutex
));
2737 cfe
= kzalloc(sizeof(*cfe
), GFP_KERNEL
);
2741 dentry
= lookup_one_len(name
, dir
, strlen(name
));
2742 if (IS_ERR(dentry
)) {
2743 error
= PTR_ERR(dentry
);
2747 cfe
->type
= (void *)cft
;
2748 cfe
->dentry
= dentry
;
2749 dentry
->d_fsdata
= cfe
;
2750 simple_xattrs_init(&cfe
->xattrs
);
2752 mode
= cgroup_file_mode(cft
);
2753 error
= cgroup_create_file(dentry
, mode
| S_IFREG
, cgrp
->root
->sb
);
2755 list_add_tail(&cfe
->node
, &parent
->files
);
2764 static int cgroup_addrm_files(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
2765 struct cftype cfts
[], bool is_add
)
2770 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
2771 /* does cft->flags tell us to skip this file on @cgrp? */
2772 if ((cft
->flags
& CFTYPE_INSANE
) && cgroup_sane_behavior(cgrp
))
2774 if ((cft
->flags
& CFTYPE_NOT_ON_ROOT
) && !cgrp
->parent
)
2776 if ((cft
->flags
& CFTYPE_ONLY_ON_ROOT
) && cgrp
->parent
)
2780 err
= cgroup_add_file(cgrp
, subsys
, cft
);
2782 pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
2786 cgroup_rm_file(cgrp
, cft
);
2792 static DEFINE_MUTEX(cgroup_cft_mutex
);
2794 static void cgroup_cfts_prepare(void)
2795 __acquires(&cgroup_cft_mutex
) __acquires(&cgroup_mutex
)
2798 * Thanks to the entanglement with vfs inode locking, we can't walk
2799 * the existing cgroups under cgroup_mutex and create files.
2800 * Instead, we increment reference on all cgroups and build list of
2801 * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure
2802 * exclusive access to the field.
2804 mutex_lock(&cgroup_cft_mutex
);
2805 mutex_lock(&cgroup_mutex
);
2808 static void cgroup_cfts_commit(struct cgroup_subsys
*ss
,
2809 struct cftype
*cfts
, bool is_add
)
2810 __releases(&cgroup_mutex
) __releases(&cgroup_cft_mutex
)
2813 struct cgroup
*cgrp
, *n
;
2815 /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
2816 if (cfts
&& ss
->root
!= &rootnode
) {
2817 list_for_each_entry(cgrp
, &ss
->root
->allcg_list
, allcg_node
) {
2819 list_add_tail(&cgrp
->cft_q_node
, &pending
);
2823 mutex_unlock(&cgroup_mutex
);
2826 * All new cgroups will see @cfts update on @ss->cftsets. Add/rm
2827 * files for all cgroups which were created before.
2829 list_for_each_entry_safe(cgrp
, n
, &pending
, cft_q_node
) {
2830 struct inode
*inode
= cgrp
->dentry
->d_inode
;
2832 mutex_lock(&inode
->i_mutex
);
2833 mutex_lock(&cgroup_mutex
);
2834 if (!cgroup_is_removed(cgrp
))
2835 cgroup_addrm_files(cgrp
, ss
, cfts
, is_add
);
2836 mutex_unlock(&cgroup_mutex
);
2837 mutex_unlock(&inode
->i_mutex
);
2839 list_del_init(&cgrp
->cft_q_node
);
2843 mutex_unlock(&cgroup_cft_mutex
);
2847 * cgroup_add_cftypes - add an array of cftypes to a subsystem
2848 * @ss: target cgroup subsystem
2849 * @cfts: zero-length name terminated array of cftypes
2851 * Register @cfts to @ss. Files described by @cfts are created for all
2852 * existing cgroups to which @ss is attached and all future cgroups will
2853 * have them too. This function can be called anytime whether @ss is
2856 * Returns 0 on successful registration, -errno on failure. Note that this
2857 * function currently returns 0 as long as @cfts registration is successful
2858 * even if some file creation attempts on existing cgroups fail.
2860 int cgroup_add_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2862 struct cftype_set
*set
;
2864 set
= kzalloc(sizeof(*set
), GFP_KERNEL
);
2868 cgroup_cfts_prepare();
2870 list_add_tail(&set
->node
, &ss
->cftsets
);
2871 cgroup_cfts_commit(ss
, cfts
, true);
2875 EXPORT_SYMBOL_GPL(cgroup_add_cftypes
);
2878 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
2879 * @ss: target cgroup subsystem
2880 * @cfts: zero-length name terminated array of cftypes
2882 * Unregister @cfts from @ss. Files described by @cfts are removed from
2883 * all existing cgroups to which @ss is attached and all future cgroups
2884 * won't have them either. This function can be called anytime whether @ss
2885 * is attached or not.
2887 * Returns 0 on successful unregistration, -ENOENT if @cfts is not
2888 * registered with @ss.
2890 int cgroup_rm_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2892 struct cftype_set
*set
;
2894 cgroup_cfts_prepare();
2896 list_for_each_entry(set
, &ss
->cftsets
, node
) {
2897 if (set
->cfts
== cfts
) {
2898 list_del_init(&set
->node
);
2899 cgroup_cfts_commit(ss
, cfts
, false);
2904 cgroup_cfts_commit(ss
, NULL
, false);
2909 * cgroup_task_count - count the number of tasks in a cgroup.
2910 * @cgrp: the cgroup in question
2912 * Return the number of tasks in the cgroup.
2914 int cgroup_task_count(const struct cgroup
*cgrp
)
2917 struct cgrp_cset_link
*link
;
2919 read_lock(&css_set_lock
);
2920 list_for_each_entry(link
, &cgrp
->cset_links
, cset_link
)
2921 count
+= atomic_read(&link
->cset
->refcount
);
2922 read_unlock(&css_set_lock
);
2927 * Advance a list_head iterator. The iterator should be positioned at
2928 * the start of a css_set
2930 static void cgroup_advance_iter(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
2932 struct list_head
*l
= it
->cset_link
;
2933 struct cgrp_cset_link
*link
;
2934 struct css_set
*cset
;
2936 /* Advance to the next non-empty css_set */
2939 if (l
== &cgrp
->cset_links
) {
2940 it
->cset_link
= NULL
;
2943 link
= list_entry(l
, struct cgrp_cset_link
, cset_link
);
2945 } while (list_empty(&cset
->tasks
));
2947 it
->task
= cset
->tasks
.next
;
2951 * To reduce the fork() overhead for systems that are not actually
2952 * using their cgroups capability, we don't maintain the lists running
2953 * through each css_set to its tasks until we see the list actually
2954 * used - in other words after the first call to cgroup_iter_start().
2956 static void cgroup_enable_task_cg_lists(void)
2958 struct task_struct
*p
, *g
;
2959 write_lock(&css_set_lock
);
2960 use_task_css_set_links
= 1;
2962 * We need tasklist_lock because RCU is not safe against
2963 * while_each_thread(). Besides, a forking task that has passed
2964 * cgroup_post_fork() without seeing use_task_css_set_links = 1
2965 * is not guaranteed to have its child immediately visible in the
2966 * tasklist if we walk through it with RCU.
2968 read_lock(&tasklist_lock
);
2969 do_each_thread(g
, p
) {
2972 * We should check if the process is exiting, otherwise
2973 * it will race with cgroup_exit() in that the list
2974 * entry won't be deleted though the process has exited.
2976 if (!(p
->flags
& PF_EXITING
) && list_empty(&p
->cg_list
))
2977 list_add(&p
->cg_list
, &p
->cgroups
->tasks
);
2979 } while_each_thread(g
, p
);
2980 read_unlock(&tasklist_lock
);
2981 write_unlock(&css_set_lock
);
2985 * cgroup_next_sibling - find the next sibling of a given cgroup
2986 * @pos: the current cgroup
2988 * This function returns the next sibling of @pos and should be called
2989 * under RCU read lock. The only requirement is that @pos is accessible.
2990 * The next sibling is guaranteed to be returned regardless of @pos's
2993 struct cgroup
*cgroup_next_sibling(struct cgroup
*pos
)
2995 struct cgroup
*next
;
2997 WARN_ON_ONCE(!rcu_read_lock_held());
3000 * @pos could already have been removed. Once a cgroup is removed,
3001 * its ->sibling.next is no longer updated when its next sibling
3002 * changes. As CGRP_REMOVED is set on removal which is fully
3003 * serialized, if we see it unasserted, it's guaranteed that the
3004 * next sibling hasn't finished its grace period even if it's
3005 * already removed, and thus safe to dereference from this RCU
3006 * critical section. If ->sibling.next is inaccessible,
3007 * cgroup_is_removed() is guaranteed to be visible as %true here.
3009 if (likely(!cgroup_is_removed(pos
))) {
3010 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup
, sibling
);
3011 if (&next
->sibling
!= &pos
->parent
->children
)
3017 * Can't dereference the next pointer. Each cgroup is given a
3018 * monotonically increasing unique serial number and always
3019 * appended to the sibling list, so the next one can be found by
3020 * walking the parent's children until we see a cgroup with higher
3021 * serial number than @pos's.
3023 * While this path can be slow, it's taken only when either the
3024 * current cgroup is removed or iteration and removal race.
3026 list_for_each_entry_rcu(next
, &pos
->parent
->children
, sibling
)
3027 if (next
->serial_nr
> pos
->serial_nr
)
3031 EXPORT_SYMBOL_GPL(cgroup_next_sibling
);
3034 * cgroup_next_descendant_pre - find the next descendant for pre-order walk
3035 * @pos: the current position (%NULL to initiate traversal)
3036 * @cgroup: cgroup whose descendants to walk
3038 * To be used by cgroup_for_each_descendant_pre(). Find the next
3039 * descendant to visit for pre-order traversal of @cgroup's descendants.
3041 * While this function requires RCU read locking, it doesn't require the
3042 * whole traversal to be contained in a single RCU critical section. This
3043 * function will return the correct next descendant as long as both @pos
3044 * and @cgroup are accessible and @pos is a descendant of @cgroup.
3046 struct cgroup
*cgroup_next_descendant_pre(struct cgroup
*pos
,
3047 struct cgroup
*cgroup
)
3049 struct cgroup
*next
;
3051 WARN_ON_ONCE(!rcu_read_lock_held());
3053 /* if first iteration, pretend we just visited @cgroup */
3057 /* visit the first child if exists */
3058 next
= list_first_or_null_rcu(&pos
->children
, struct cgroup
, sibling
);
3062 /* no child, visit my or the closest ancestor's next sibling */
3063 while (pos
!= cgroup
) {
3064 next
= cgroup_next_sibling(pos
);
3072 EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre
);
3075 * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup
3076 * @pos: cgroup of interest
3078 * Return the rightmost descendant of @pos. If there's no descendant,
3079 * @pos is returned. This can be used during pre-order traversal to skip
3082 * While this function requires RCU read locking, it doesn't require the
3083 * whole traversal to be contained in a single RCU critical section. This
3084 * function will return the correct rightmost descendant as long as @pos is
3087 struct cgroup
*cgroup_rightmost_descendant(struct cgroup
*pos
)
3089 struct cgroup
*last
, *tmp
;
3091 WARN_ON_ONCE(!rcu_read_lock_held());
3095 /* ->prev isn't RCU safe, walk ->next till the end */
3097 list_for_each_entry_rcu(tmp
, &last
->children
, sibling
)
3103 EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant
);
3105 static struct cgroup
*cgroup_leftmost_descendant(struct cgroup
*pos
)
3107 struct cgroup
*last
;
3111 pos
= list_first_or_null_rcu(&pos
->children
, struct cgroup
,
3119 * cgroup_next_descendant_post - find the next descendant for post-order walk
3120 * @pos: the current position (%NULL to initiate traversal)
3121 * @cgroup: cgroup whose descendants to walk
3123 * To be used by cgroup_for_each_descendant_post(). Find the next
3124 * descendant to visit for post-order traversal of @cgroup's descendants.
3126 * While this function requires RCU read locking, it doesn't require the
3127 * whole traversal to be contained in a single RCU critical section. This
3128 * function will return the correct next descendant as long as both @pos
3129 * and @cgroup are accessible and @pos is a descendant of @cgroup.
3131 struct cgroup
*cgroup_next_descendant_post(struct cgroup
*pos
,
3132 struct cgroup
*cgroup
)
3134 struct cgroup
*next
;
3136 WARN_ON_ONCE(!rcu_read_lock_held());
3138 /* if first iteration, visit the leftmost descendant */
3140 next
= cgroup_leftmost_descendant(cgroup
);
3141 return next
!= cgroup
? next
: NULL
;
3144 /* if there's an unvisited sibling, visit its leftmost descendant */
3145 next
= cgroup_next_sibling(pos
);
3147 return cgroup_leftmost_descendant(next
);
3149 /* no sibling left, visit parent */
3151 return next
!= cgroup
? next
: NULL
;
3153 EXPORT_SYMBOL_GPL(cgroup_next_descendant_post
);
3155 void cgroup_iter_start(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
3156 __acquires(css_set_lock
)
3159 * The first time anyone tries to iterate across a cgroup,
3160 * we need to enable the list linking each css_set to its
3161 * tasks, and fix up all existing tasks.
3163 if (!use_task_css_set_links
)
3164 cgroup_enable_task_cg_lists();
3166 read_lock(&css_set_lock
);
3167 it
->cset_link
= &cgrp
->cset_links
;
3168 cgroup_advance_iter(cgrp
, it
);
3171 struct task_struct
*cgroup_iter_next(struct cgroup
*cgrp
,
3172 struct cgroup_iter
*it
)
3174 struct task_struct
*res
;
3175 struct list_head
*l
= it
->task
;
3176 struct cgrp_cset_link
*link
;
3178 /* If the iterator cg is NULL, we have no tasks */
3181 res
= list_entry(l
, struct task_struct
, cg_list
);
3182 /* Advance iterator to find next entry */
3184 link
= list_entry(it
->cset_link
, struct cgrp_cset_link
, cset_link
);
3185 if (l
== &link
->cset
->tasks
) {
3186 /* We reached the end of this task list - move on to
3187 * the next cg_cgroup_link */
3188 cgroup_advance_iter(cgrp
, it
);
3195 void cgroup_iter_end(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
3196 __releases(css_set_lock
)
3198 read_unlock(&css_set_lock
);
3201 static inline int started_after_time(struct task_struct
*t1
,
3202 struct timespec
*time
,
3203 struct task_struct
*t2
)
3205 int start_diff
= timespec_compare(&t1
->start_time
, time
);
3206 if (start_diff
> 0) {
3208 } else if (start_diff
< 0) {
3212 * Arbitrarily, if two processes started at the same
3213 * time, we'll say that the lower pointer value
3214 * started first. Note that t2 may have exited by now
3215 * so this may not be a valid pointer any longer, but
3216 * that's fine - it still serves to distinguish
3217 * between two tasks started (effectively) simultaneously.
3224 * This function is a callback from heap_insert() and is used to order
3226 * In this case we order the heap in descending task start time.
3228 static inline int started_after(void *p1
, void *p2
)
3230 struct task_struct
*t1
= p1
;
3231 struct task_struct
*t2
= p2
;
3232 return started_after_time(t1
, &t2
->start_time
, t2
);
3236 * cgroup_scan_tasks - iterate though all the tasks in a cgroup
3237 * @scan: struct cgroup_scanner containing arguments for the scan
3239 * Arguments include pointers to callback functions test_task() and
3241 * Iterate through all the tasks in a cgroup, calling test_task() for each,
3242 * and if it returns true, call process_task() for it also.
3243 * The test_task pointer may be NULL, meaning always true (select all tasks).
3244 * Effectively duplicates cgroup_iter_{start,next,end}()
3245 * but does not lock css_set_lock for the call to process_task().
3246 * The struct cgroup_scanner may be embedded in any structure of the caller's
3248 * It is guaranteed that process_task() will act on every task that
3249 * is a member of the cgroup for the duration of this call. This
3250 * function may or may not call process_task() for tasks that exit
3251 * or move to a different cgroup during the call, or are forked or
3252 * move into the cgroup during the call.
3254 * Note that test_task() may be called with locks held, and may in some
3255 * situations be called multiple times for the same task, so it should
3257 * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
3258 * pre-allocated and will be used for heap operations (and its "gt" member will
3259 * be overwritten), else a temporary heap will be used (allocation of which
3260 * may cause this function to fail).
3262 int cgroup_scan_tasks(struct cgroup_scanner
*scan
)
3265 struct cgroup_iter it
;
3266 struct task_struct
*p
, *dropped
;
3267 /* Never dereference latest_task, since it's not refcounted */
3268 struct task_struct
*latest_task
= NULL
;
3269 struct ptr_heap tmp_heap
;
3270 struct ptr_heap
*heap
;
3271 struct timespec latest_time
= { 0, 0 };
3274 /* The caller supplied our heap and pre-allocated its memory */
3276 heap
->gt
= &started_after
;
3278 /* We need to allocate our own heap memory */
3280 retval
= heap_init(heap
, PAGE_SIZE
, GFP_KERNEL
, &started_after
);
3282 /* cannot allocate the heap */
3288 * Scan tasks in the cgroup, using the scanner's "test_task" callback
3289 * to determine which are of interest, and using the scanner's
3290 * "process_task" callback to process any of them that need an update.
3291 * Since we don't want to hold any locks during the task updates,
3292 * gather tasks to be processed in a heap structure.
3293 * The heap is sorted by descending task start time.
3294 * If the statically-sized heap fills up, we overflow tasks that
3295 * started later, and in future iterations only consider tasks that
3296 * started after the latest task in the previous pass. This
3297 * guarantees forward progress and that we don't miss any tasks.
3300 cgroup_iter_start(scan
->cg
, &it
);
3301 while ((p
= cgroup_iter_next(scan
->cg
, &it
))) {
3303 * Only affect tasks that qualify per the caller's callback,
3304 * if he provided one
3306 if (scan
->test_task
&& !scan
->test_task(p
, scan
))
3309 * Only process tasks that started after the last task
3312 if (!started_after_time(p
, &latest_time
, latest_task
))
3314 dropped
= heap_insert(heap
, p
);
3315 if (dropped
== NULL
) {
3317 * The new task was inserted; the heap wasn't
3321 } else if (dropped
!= p
) {
3323 * The new task was inserted, and pushed out a
3327 put_task_struct(dropped
);
3330 * Else the new task was newer than anything already in
3331 * the heap and wasn't inserted
3334 cgroup_iter_end(scan
->cg
, &it
);
3337 for (i
= 0; i
< heap
->size
; i
++) {
3338 struct task_struct
*q
= heap
->ptrs
[i
];
3340 latest_time
= q
->start_time
;
3343 /* Process the task per the caller's callback */
3344 scan
->process_task(q
, scan
);
3348 * If we had to process any tasks at all, scan again
3349 * in case some of them were in the middle of forking
3350 * children that didn't get processed.
3351 * Not the most efficient way to do it, but it avoids
3352 * having to take callback_mutex in the fork path
3356 if (heap
== &tmp_heap
)
3357 heap_free(&tmp_heap
);
3361 static void cgroup_transfer_one_task(struct task_struct
*task
,
3362 struct cgroup_scanner
*scan
)
3364 struct cgroup
*new_cgroup
= scan
->data
;
3366 mutex_lock(&cgroup_mutex
);
3367 cgroup_attach_task(new_cgroup
, task
, false);
3368 mutex_unlock(&cgroup_mutex
);
3372 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
3373 * @to: cgroup to which the tasks will be moved
3374 * @from: cgroup in which the tasks currently reside
3376 int cgroup_transfer_tasks(struct cgroup
*to
, struct cgroup
*from
)
3378 struct cgroup_scanner scan
;
3381 scan
.test_task
= NULL
; /* select all tasks in cgroup */
3382 scan
.process_task
= cgroup_transfer_one_task
;
3386 return cgroup_scan_tasks(&scan
);
3390 * Stuff for reading the 'tasks'/'procs' files.
3392 * Reading this file can return large amounts of data if a cgroup has
3393 * *lots* of attached tasks. So it may need several calls to read(),
3394 * but we cannot guarantee that the information we produce is correct
3395 * unless we produce it entirely atomically.
3399 /* which pidlist file are we talking about? */
3400 enum cgroup_filetype
{
3406 * A pidlist is a list of pids that virtually represents the contents of one
3407 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
3408 * a pair (one each for procs, tasks) for each pid namespace that's relevant
3411 struct cgroup_pidlist
{
3413 * used to find which pidlist is wanted. doesn't change as long as
3414 * this particular list stays in the list.
3416 struct { enum cgroup_filetype type
; struct pid_namespace
*ns
; } key
;
3419 /* how many elements the above list has */
3421 /* how many files are using the current array */
3423 /* each of these stored in a list by its cgroup */
3424 struct list_head links
;
3425 /* pointer to the cgroup we belong to, for list removal purposes */
3426 struct cgroup
*owner
;
3427 /* protects the other fields */
3428 struct rw_semaphore mutex
;
3432 * The following two functions "fix" the issue where there are more pids
3433 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
3434 * TODO: replace with a kernel-wide solution to this problem
3436 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
3437 static void *pidlist_allocate(int count
)
3439 if (PIDLIST_TOO_LARGE(count
))
3440 return vmalloc(count
* sizeof(pid_t
));
3442 return kmalloc(count
* sizeof(pid_t
), GFP_KERNEL
);
3444 static void pidlist_free(void *p
)
3446 if (is_vmalloc_addr(p
))
3453 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
3454 * Returns the number of unique elements.
3456 static int pidlist_uniq(pid_t
*list
, int length
)
3461 * we presume the 0th element is unique, so i starts at 1. trivial
3462 * edge cases first; no work needs to be done for either
3464 if (length
== 0 || length
== 1)
3466 /* src and dest walk down the list; dest counts unique elements */
3467 for (src
= 1; src
< length
; src
++) {
3468 /* find next unique element */
3469 while (list
[src
] == list
[src
-1]) {
3474 /* dest always points to where the next unique element goes */
3475 list
[dest
] = list
[src
];
3482 static int cmppid(const void *a
, const void *b
)
3484 return *(pid_t
*)a
- *(pid_t
*)b
;
3488 * find the appropriate pidlist for our purpose (given procs vs tasks)
3489 * returns with the lock on that pidlist already held, and takes care
3490 * of the use count, or returns NULL with no locks held if we're out of
3493 static struct cgroup_pidlist
*cgroup_pidlist_find(struct cgroup
*cgrp
,
3494 enum cgroup_filetype type
)
3496 struct cgroup_pidlist
*l
;
3497 /* don't need task_nsproxy() if we're looking at ourself */
3498 struct pid_namespace
*ns
= task_active_pid_ns(current
);
3501 * We can't drop the pidlist_mutex before taking the l->mutex in case
3502 * the last ref-holder is trying to remove l from the list at the same
3503 * time. Holding the pidlist_mutex precludes somebody taking whichever
3504 * list we find out from under us - compare release_pid_array().
3506 mutex_lock(&cgrp
->pidlist_mutex
);
3507 list_for_each_entry(l
, &cgrp
->pidlists
, links
) {
3508 if (l
->key
.type
== type
&& l
->key
.ns
== ns
) {
3509 /* make sure l doesn't vanish out from under us */
3510 down_write(&l
->mutex
);
3511 mutex_unlock(&cgrp
->pidlist_mutex
);
3515 /* entry not found; create a new one */
3516 l
= kzalloc(sizeof(struct cgroup_pidlist
), GFP_KERNEL
);
3518 mutex_unlock(&cgrp
->pidlist_mutex
);
3521 init_rwsem(&l
->mutex
);
3522 down_write(&l
->mutex
);
3524 l
->key
.ns
= get_pid_ns(ns
);
3526 list_add(&l
->links
, &cgrp
->pidlists
);
3527 mutex_unlock(&cgrp
->pidlist_mutex
);
3532 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
3534 static int pidlist_array_load(struct cgroup
*cgrp
, enum cgroup_filetype type
,
3535 struct cgroup_pidlist
**lp
)
3539 int pid
, n
= 0; /* used for populating the array */
3540 struct cgroup_iter it
;
3541 struct task_struct
*tsk
;
3542 struct cgroup_pidlist
*l
;
3545 * If cgroup gets more users after we read count, we won't have
3546 * enough space - tough. This race is indistinguishable to the
3547 * caller from the case that the additional cgroup users didn't
3548 * show up until sometime later on.
3550 length
= cgroup_task_count(cgrp
);
3551 array
= pidlist_allocate(length
);
3554 /* now, populate the array */
3555 cgroup_iter_start(cgrp
, &it
);
3556 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
3557 if (unlikely(n
== length
))
3559 /* get tgid or pid for procs or tasks file respectively */
3560 if (type
== CGROUP_FILE_PROCS
)
3561 pid
= task_tgid_vnr(tsk
);
3563 pid
= task_pid_vnr(tsk
);
3564 if (pid
> 0) /* make sure to only use valid results */
3567 cgroup_iter_end(cgrp
, &it
);
3569 /* now sort & (if procs) strip out duplicates */
3570 sort(array
, length
, sizeof(pid_t
), cmppid
, NULL
);
3571 if (type
== CGROUP_FILE_PROCS
)
3572 length
= pidlist_uniq(array
, length
);
3573 l
= cgroup_pidlist_find(cgrp
, type
);
3575 pidlist_free(array
);
3578 /* store array, freeing old if necessary - lock already held */
3579 pidlist_free(l
->list
);
3583 up_write(&l
->mutex
);
3589 * cgroupstats_build - build and fill cgroupstats
3590 * @stats: cgroupstats to fill information into
3591 * @dentry: A dentry entry belonging to the cgroup for which stats have
3594 * Build and fill cgroupstats so that taskstats can export it to user
3597 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
3600 struct cgroup
*cgrp
;
3601 struct cgroup_iter it
;
3602 struct task_struct
*tsk
;
3605 * Validate dentry by checking the superblock operations,
3606 * and make sure it's a directory.
3608 if (dentry
->d_sb
->s_op
!= &cgroup_ops
||
3609 !S_ISDIR(dentry
->d_inode
->i_mode
))
3613 cgrp
= dentry
->d_fsdata
;
3615 cgroup_iter_start(cgrp
, &it
);
3616 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
3617 switch (tsk
->state
) {
3619 stats
->nr_running
++;
3621 case TASK_INTERRUPTIBLE
:
3622 stats
->nr_sleeping
++;
3624 case TASK_UNINTERRUPTIBLE
:
3625 stats
->nr_uninterruptible
++;
3628 stats
->nr_stopped
++;
3631 if (delayacct_is_task_waiting_on_io(tsk
))
3632 stats
->nr_io_wait
++;
3636 cgroup_iter_end(cgrp
, &it
);
3644 * seq_file methods for the tasks/procs files. The seq_file position is the
3645 * next pid to display; the seq_file iterator is a pointer to the pid
3646 * in the cgroup->l->list array.
3649 static void *cgroup_pidlist_start(struct seq_file
*s
, loff_t
*pos
)
3652 * Initially we receive a position value that corresponds to
3653 * one more than the last pid shown (or 0 on the first call or
3654 * after a seek to the start). Use a binary-search to find the
3655 * next pid to display, if any
3657 struct cgroup_pidlist
*l
= s
->private;
3658 int index
= 0, pid
= *pos
;
3661 down_read(&l
->mutex
);
3663 int end
= l
->length
;
3665 while (index
< end
) {
3666 int mid
= (index
+ end
) / 2;
3667 if (l
->list
[mid
] == pid
) {
3670 } else if (l
->list
[mid
] <= pid
)
3676 /* If we're off the end of the array, we're done */
3677 if (index
>= l
->length
)
3679 /* Update the abstract position to be the actual pid that we found */
3680 iter
= l
->list
+ index
;
3685 static void cgroup_pidlist_stop(struct seq_file
*s
, void *v
)
3687 struct cgroup_pidlist
*l
= s
->private;
3691 static void *cgroup_pidlist_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
3693 struct cgroup_pidlist
*l
= s
->private;
3695 pid_t
*end
= l
->list
+ l
->length
;
3697 * Advance to the next pid in the array. If this goes off the
3709 static int cgroup_pidlist_show(struct seq_file
*s
, void *v
)
3711 return seq_printf(s
, "%d\n", *(int *)v
);
3715 * seq_operations functions for iterating on pidlists through seq_file -
3716 * independent of whether it's tasks or procs
3718 static const struct seq_operations cgroup_pidlist_seq_operations
= {
3719 .start
= cgroup_pidlist_start
,
3720 .stop
= cgroup_pidlist_stop
,
3721 .next
= cgroup_pidlist_next
,
3722 .show
= cgroup_pidlist_show
,
3725 static void cgroup_release_pid_array(struct cgroup_pidlist
*l
)
3728 * the case where we're the last user of this particular pidlist will
3729 * have us remove it from the cgroup's list, which entails taking the
3730 * mutex. since in pidlist_find the pidlist->lock depends on cgroup->
3731 * pidlist_mutex, we have to take pidlist_mutex first.
3733 mutex_lock(&l
->owner
->pidlist_mutex
);
3734 down_write(&l
->mutex
);
3735 BUG_ON(!l
->use_count
);
3736 if (!--l
->use_count
) {
3737 /* we're the last user if refcount is 0; remove and free */
3738 list_del(&l
->links
);
3739 mutex_unlock(&l
->owner
->pidlist_mutex
);
3740 pidlist_free(l
->list
);
3741 put_pid_ns(l
->key
.ns
);
3742 up_write(&l
->mutex
);
3746 mutex_unlock(&l
->owner
->pidlist_mutex
);
3747 up_write(&l
->mutex
);
3750 static int cgroup_pidlist_release(struct inode
*inode
, struct file
*file
)
3752 struct cgroup_pidlist
*l
;
3753 if (!(file
->f_mode
& FMODE_READ
))
3756 * the seq_file will only be initialized if the file was opened for
3757 * reading; hence we check if it's not null only in that case.
3759 l
= ((struct seq_file
*)file
->private_data
)->private;
3760 cgroup_release_pid_array(l
);
3761 return seq_release(inode
, file
);
3764 static const struct file_operations cgroup_pidlist_operations
= {
3766 .llseek
= seq_lseek
,
3767 .write
= cgroup_file_write
,
3768 .release
= cgroup_pidlist_release
,
3772 * The following functions handle opens on a file that displays a pidlist
3773 * (tasks or procs). Prepare an array of the process/thread IDs of whoever's
3776 /* helper function for the two below it */
3777 static int cgroup_pidlist_open(struct file
*file
, enum cgroup_filetype type
)
3779 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
3780 struct cgroup_pidlist
*l
;
3783 /* Nothing to do for write-only files */
3784 if (!(file
->f_mode
& FMODE_READ
))
3787 /* have the array populated */
3788 retval
= pidlist_array_load(cgrp
, type
, &l
);
3791 /* configure file information */
3792 file
->f_op
= &cgroup_pidlist_operations
;
3794 retval
= seq_open(file
, &cgroup_pidlist_seq_operations
);
3796 cgroup_release_pid_array(l
);
3799 ((struct seq_file
*)file
->private_data
)->private = l
;
3802 static int cgroup_tasks_open(struct inode
*unused
, struct file
*file
)
3804 return cgroup_pidlist_open(file
, CGROUP_FILE_TASKS
);
3806 static int cgroup_procs_open(struct inode
*unused
, struct file
*file
)
3808 return cgroup_pidlist_open(file
, CGROUP_FILE_PROCS
);
3811 static u64
cgroup_read_notify_on_release(struct cgroup
*cgrp
,
3814 return notify_on_release(cgrp
);
3817 static int cgroup_write_notify_on_release(struct cgroup
*cgrp
,
3821 clear_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
3823 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3825 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3830 * Unregister event and free resources.
3832 * Gets called from workqueue.
3834 static void cgroup_event_remove(struct work_struct
*work
)
3836 struct cgroup_event
*event
= container_of(work
, struct cgroup_event
,
3838 struct cgroup
*cgrp
= event
->cgrp
;
3840 remove_wait_queue(event
->wqh
, &event
->wait
);
3842 event
->cft
->unregister_event(cgrp
, event
->cft
, event
->eventfd
);
3844 /* Notify userspace the event is going away. */
3845 eventfd_signal(event
->eventfd
, 1);
3847 eventfd_ctx_put(event
->eventfd
);
3853 * Gets called on POLLHUP on eventfd when user closes it.
3855 * Called with wqh->lock held and interrupts disabled.
3857 static int cgroup_event_wake(wait_queue_t
*wait
, unsigned mode
,
3858 int sync
, void *key
)
3860 struct cgroup_event
*event
= container_of(wait
,
3861 struct cgroup_event
, wait
);
3862 struct cgroup
*cgrp
= event
->cgrp
;
3863 unsigned long flags
= (unsigned long)key
;
3865 if (flags
& POLLHUP
) {
3867 * If the event has been detached at cgroup removal, we
3868 * can simply return knowing the other side will cleanup
3871 * We can't race against event freeing since the other
3872 * side will require wqh->lock via remove_wait_queue(),
3875 spin_lock(&cgrp
->event_list_lock
);
3876 if (!list_empty(&event
->list
)) {
3877 list_del_init(&event
->list
);
3879 * We are in atomic context, but cgroup_event_remove()
3880 * may sleep, so we have to call it in workqueue.
3882 schedule_work(&event
->remove
);
3884 spin_unlock(&cgrp
->event_list_lock
);
3890 static void cgroup_event_ptable_queue_proc(struct file
*file
,
3891 wait_queue_head_t
*wqh
, poll_table
*pt
)
3893 struct cgroup_event
*event
= container_of(pt
,
3894 struct cgroup_event
, pt
);
3897 add_wait_queue(wqh
, &event
->wait
);
3901 * Parse input and register new cgroup event handler.
3903 * Input must be in format '<event_fd> <control_fd> <args>'.
3904 * Interpretation of args is defined by control file implementation.
3906 static int cgroup_write_event_control(struct cgroup
*cgrp
, struct cftype
*cft
,
3909 struct cgroup_event
*event
= NULL
;
3910 struct cgroup
*cgrp_cfile
;
3911 unsigned int efd
, cfd
;
3912 struct file
*efile
= NULL
;
3913 struct file
*cfile
= NULL
;
3917 efd
= simple_strtoul(buffer
, &endp
, 10);
3922 cfd
= simple_strtoul(buffer
, &endp
, 10);
3923 if ((*endp
!= ' ') && (*endp
!= '\0'))
3927 event
= kzalloc(sizeof(*event
), GFP_KERNEL
);
3931 INIT_LIST_HEAD(&event
->list
);
3932 init_poll_funcptr(&event
->pt
, cgroup_event_ptable_queue_proc
);
3933 init_waitqueue_func_entry(&event
->wait
, cgroup_event_wake
);
3934 INIT_WORK(&event
->remove
, cgroup_event_remove
);
3936 efile
= eventfd_fget(efd
);
3937 if (IS_ERR(efile
)) {
3938 ret
= PTR_ERR(efile
);
3942 event
->eventfd
= eventfd_ctx_fileget(efile
);
3943 if (IS_ERR(event
->eventfd
)) {
3944 ret
= PTR_ERR(event
->eventfd
);
3954 /* the process need read permission on control file */
3955 /* AV: shouldn't we check that it's been opened for read instead? */
3956 ret
= inode_permission(file_inode(cfile
), MAY_READ
);
3960 event
->cft
= __file_cft(cfile
);
3961 if (IS_ERR(event
->cft
)) {
3962 ret
= PTR_ERR(event
->cft
);
3967 * The file to be monitored must be in the same cgroup as
3968 * cgroup.event_control is.
3970 cgrp_cfile
= __d_cgrp(cfile
->f_dentry
->d_parent
);
3971 if (cgrp_cfile
!= cgrp
) {
3976 if (!event
->cft
->register_event
|| !event
->cft
->unregister_event
) {
3981 ret
= event
->cft
->register_event(cgrp
, event
->cft
,
3982 event
->eventfd
, buffer
);
3986 efile
->f_op
->poll(efile
, &event
->pt
);
3989 * Events should be removed after rmdir of cgroup directory, but before
3990 * destroying subsystem state objects. Let's take reference to cgroup
3991 * directory dentry to do that.
3995 spin_lock(&cgrp
->event_list_lock
);
3996 list_add(&event
->list
, &cgrp
->event_list
);
3997 spin_unlock(&cgrp
->event_list_lock
);
4008 if (event
&& event
->eventfd
&& !IS_ERR(event
->eventfd
))
4009 eventfd_ctx_put(event
->eventfd
);
4011 if (!IS_ERR_OR_NULL(efile
))
4019 static u64
cgroup_clone_children_read(struct cgroup
*cgrp
,
4022 return test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
4025 static int cgroup_clone_children_write(struct cgroup
*cgrp
,
4030 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
4032 clear_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
4036 static struct cftype cgroup_base_files
[] = {
4038 .name
= "cgroup.procs",
4039 .open
= cgroup_procs_open
,
4040 .write_u64
= cgroup_procs_write
,
4041 .release
= cgroup_pidlist_release
,
4042 .mode
= S_IRUGO
| S_IWUSR
,
4045 .name
= "cgroup.event_control",
4046 .write_string
= cgroup_write_event_control
,
4050 .name
= "cgroup.clone_children",
4051 .flags
= CFTYPE_INSANE
,
4052 .read_u64
= cgroup_clone_children_read
,
4053 .write_u64
= cgroup_clone_children_write
,
4056 .name
= "cgroup.sane_behavior",
4057 .flags
= CFTYPE_ONLY_ON_ROOT
,
4058 .read_seq_string
= cgroup_sane_behavior_show
,
4062 * Historical crazy stuff. These don't have "cgroup." prefix and
4063 * don't exist if sane_behavior. If you're depending on these, be
4064 * prepared to be burned.
4068 .flags
= CFTYPE_INSANE
, /* use "procs" instead */
4069 .open
= cgroup_tasks_open
,
4070 .write_u64
= cgroup_tasks_write
,
4071 .release
= cgroup_pidlist_release
,
4072 .mode
= S_IRUGO
| S_IWUSR
,
4075 .name
= "notify_on_release",
4076 .flags
= CFTYPE_INSANE
,
4077 .read_u64
= cgroup_read_notify_on_release
,
4078 .write_u64
= cgroup_write_notify_on_release
,
4081 .name
= "release_agent",
4082 .flags
= CFTYPE_INSANE
| CFTYPE_ONLY_ON_ROOT
,
4083 .read_seq_string
= cgroup_release_agent_show
,
4084 .write_string
= cgroup_release_agent_write
,
4085 .max_write_len
= PATH_MAX
,
4091 * cgroup_populate_dir - selectively creation of files in a directory
4092 * @cgrp: target cgroup
4093 * @base_files: true if the base files should be added
4094 * @subsys_mask: mask of the subsystem ids whose files should be added
4096 static int cgroup_populate_dir(struct cgroup
*cgrp
, bool base_files
,
4097 unsigned long subsys_mask
)
4100 struct cgroup_subsys
*ss
;
4103 err
= cgroup_addrm_files(cgrp
, NULL
, cgroup_base_files
, true);
4108 /* process cftsets of each subsystem */
4109 for_each_subsys(cgrp
->root
, ss
) {
4110 struct cftype_set
*set
;
4111 if (!test_bit(ss
->subsys_id
, &subsys_mask
))
4114 list_for_each_entry(set
, &ss
->cftsets
, node
)
4115 cgroup_addrm_files(cgrp
, ss
, set
->cfts
, true);
4118 /* This cgroup is ready now */
4119 for_each_subsys(cgrp
->root
, ss
) {
4120 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4122 * Update id->css pointer and make this css visible from
4123 * CSS ID functions. This pointer will be dereferened
4124 * from RCU-read-side without locks.
4127 rcu_assign_pointer(css
->id
->css
, css
);
4133 static void css_dput_fn(struct work_struct
*work
)
4135 struct cgroup_subsys_state
*css
=
4136 container_of(work
, struct cgroup_subsys_state
, dput_work
);
4137 struct dentry
*dentry
= css
->cgroup
->dentry
;
4138 struct super_block
*sb
= dentry
->d_sb
;
4140 atomic_inc(&sb
->s_active
);
4142 deactivate_super(sb
);
4145 static void init_cgroup_css(struct cgroup_subsys_state
*css
,
4146 struct cgroup_subsys
*ss
,
4147 struct cgroup
*cgrp
)
4150 atomic_set(&css
->refcnt
, 1);
4153 if (cgrp
== dummytop
)
4154 css
->flags
|= CSS_ROOT
;
4155 BUG_ON(cgrp
->subsys
[ss
->subsys_id
]);
4156 cgrp
->subsys
[ss
->subsys_id
] = css
;
4159 * css holds an extra ref to @cgrp->dentry which is put on the last
4160 * css_put(). dput() requires process context, which css_put() may
4161 * be called without. @css->dput_work will be used to invoke
4162 * dput() asynchronously from css_put().
4164 INIT_WORK(&css
->dput_work
, css_dput_fn
);
4167 /* invoke ->post_create() on a new CSS and mark it online if successful */
4168 static int online_css(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4172 lockdep_assert_held(&cgroup_mutex
);
4175 ret
= ss
->css_online(cgrp
);
4177 cgrp
->subsys
[ss
->subsys_id
]->flags
|= CSS_ONLINE
;
4181 /* if the CSS is online, invoke ->pre_destory() on it and mark it offline */
4182 static void offline_css(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4183 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
4185 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4187 lockdep_assert_held(&cgroup_mutex
);
4189 if (!(css
->flags
& CSS_ONLINE
))
4192 if (ss
->css_offline
)
4193 ss
->css_offline(cgrp
);
4195 cgrp
->subsys
[ss
->subsys_id
]->flags
&= ~CSS_ONLINE
;
4199 * cgroup_create - create a cgroup
4200 * @parent: cgroup that will be parent of the new cgroup
4201 * @dentry: dentry of the new cgroup
4202 * @mode: mode to set on new inode
4204 * Must be called with the mutex on the parent inode held
4206 static long cgroup_create(struct cgroup
*parent
, struct dentry
*dentry
,
4209 static atomic64_t serial_nr_cursor
= ATOMIC64_INIT(0);
4210 struct cgroup
*cgrp
;
4211 struct cgroup_name
*name
;
4212 struct cgroupfs_root
*root
= parent
->root
;
4214 struct cgroup_subsys
*ss
;
4215 struct super_block
*sb
= root
->sb
;
4217 /* allocate the cgroup and its ID, 0 is reserved for the root */
4218 cgrp
= kzalloc(sizeof(*cgrp
), GFP_KERNEL
);
4222 name
= cgroup_alloc_name(dentry
);
4225 rcu_assign_pointer(cgrp
->name
, name
);
4227 cgrp
->id
= ida_simple_get(&root
->cgroup_ida
, 1, 0, GFP_KERNEL
);
4232 * Only live parents can have children. Note that the liveliness
4233 * check isn't strictly necessary because cgroup_mkdir() and
4234 * cgroup_rmdir() are fully synchronized by i_mutex; however, do it
4235 * anyway so that locking is contained inside cgroup proper and we
4236 * don't get nasty surprises if we ever grow another caller.
4238 if (!cgroup_lock_live_group(parent
)) {
4243 /* Grab a reference on the superblock so the hierarchy doesn't
4244 * get deleted on unmount if there are child cgroups. This
4245 * can be done outside cgroup_mutex, since the sb can't
4246 * disappear while someone has an open control file on the
4248 atomic_inc(&sb
->s_active
);
4250 init_cgroup_housekeeping(cgrp
);
4252 dentry
->d_fsdata
= cgrp
;
4253 cgrp
->dentry
= dentry
;
4255 cgrp
->parent
= parent
;
4256 cgrp
->root
= parent
->root
;
4258 if (notify_on_release(parent
))
4259 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
4261 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
))
4262 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
4264 for_each_subsys(root
, ss
) {
4265 struct cgroup_subsys_state
*css
;
4267 css
= ss
->css_alloc(cgrp
);
4272 init_cgroup_css(css
, ss
, cgrp
);
4274 err
= alloc_css_id(ss
, parent
, cgrp
);
4281 * Create directory. cgroup_create_file() returns with the new
4282 * directory locked on success so that it can be populated without
4283 * dropping cgroup_mutex.
4285 err
= cgroup_create_file(dentry
, S_IFDIR
| mode
, sb
);
4288 lockdep_assert_held(&dentry
->d_inode
->i_mutex
);
4291 * Assign a monotonically increasing serial number. With the list
4292 * appending below, it guarantees that sibling cgroups are always
4293 * sorted in the ascending serial number order on the parent's
4296 cgrp
->serial_nr
= atomic64_inc_return(&serial_nr_cursor
);
4298 /* allocation complete, commit to creation */
4299 list_add_tail(&cgrp
->allcg_node
, &root
->allcg_list
);
4300 list_add_tail_rcu(&cgrp
->sibling
, &cgrp
->parent
->children
);
4301 root
->number_of_cgroups
++;
4303 /* each css holds a ref to the cgroup's dentry */
4304 for_each_subsys(root
, ss
)
4307 /* hold a ref to the parent's dentry */
4308 dget(parent
->dentry
);
4310 /* creation succeeded, notify subsystems */
4311 for_each_subsys(root
, ss
) {
4312 err
= online_css(ss
, cgrp
);
4316 if (ss
->broken_hierarchy
&& !ss
->warned_broken_hierarchy
&&
4318 pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
4319 current
->comm
, current
->pid
, ss
->name
);
4320 if (!strcmp(ss
->name
, "memory"))
4321 pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
4322 ss
->warned_broken_hierarchy
= true;
4326 err
= cgroup_populate_dir(cgrp
, true, root
->subsys_mask
);
4330 mutex_unlock(&cgroup_mutex
);
4331 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
4336 for_each_subsys(root
, ss
) {
4337 if (cgrp
->subsys
[ss
->subsys_id
])
4340 mutex_unlock(&cgroup_mutex
);
4341 /* Release the reference count that we took on the superblock */
4342 deactivate_super(sb
);
4344 ida_simple_remove(&root
->cgroup_ida
, cgrp
->id
);
4346 kfree(rcu_dereference_raw(cgrp
->name
));
4352 cgroup_destroy_locked(cgrp
);
4353 mutex_unlock(&cgroup_mutex
);
4354 mutex_unlock(&dentry
->d_inode
->i_mutex
);
4358 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
4360 struct cgroup
*c_parent
= dentry
->d_parent
->d_fsdata
;
4362 /* the vfs holds inode->i_mutex already */
4363 return cgroup_create(c_parent
, dentry
, mode
| S_IFDIR
);
4366 static int cgroup_destroy_locked(struct cgroup
*cgrp
)
4367 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
4369 struct dentry
*d
= cgrp
->dentry
;
4370 struct cgroup
*parent
= cgrp
->parent
;
4371 struct cgroup_event
*event
, *tmp
;
4372 struct cgroup_subsys
*ss
;
4374 lockdep_assert_held(&d
->d_inode
->i_mutex
);
4375 lockdep_assert_held(&cgroup_mutex
);
4377 if (atomic_read(&cgrp
->count
) || !list_empty(&cgrp
->children
))
4381 * Block new css_tryget() by deactivating refcnt and mark @cgrp
4382 * removed. This makes future css_tryget() and child creation
4383 * attempts fail thus maintaining the removal conditions verified
4386 * Note that CGRP_REMVOED clearing is depended upon by
4387 * cgroup_next_sibling() to resume iteration after dropping RCU
4388 * read lock. See cgroup_next_sibling() for details.
4390 for_each_subsys(cgrp
->root
, ss
) {
4391 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4393 WARN_ON(atomic_read(&css
->refcnt
) < 0);
4394 atomic_add(CSS_DEACT_BIAS
, &css
->refcnt
);
4396 set_bit(CGRP_REMOVED
, &cgrp
->flags
);
4398 /* tell subsystems to initate destruction */
4399 for_each_subsys(cgrp
->root
, ss
)
4400 offline_css(ss
, cgrp
);
4403 * Put all the base refs. Each css holds an extra reference to the
4404 * cgroup's dentry and cgroup removal proceeds regardless of css
4405 * refs. On the last put of each css, whenever that may be, the
4406 * extra dentry ref is put so that dentry destruction happens only
4407 * after all css's are released.
4409 for_each_subsys(cgrp
->root
, ss
)
4410 css_put(cgrp
->subsys
[ss
->subsys_id
]);
4412 raw_spin_lock(&release_list_lock
);
4413 if (!list_empty(&cgrp
->release_list
))
4414 list_del_init(&cgrp
->release_list
);
4415 raw_spin_unlock(&release_list_lock
);
4417 /* delete this cgroup from parent->children */
4418 list_del_rcu(&cgrp
->sibling
);
4419 list_del_init(&cgrp
->allcg_node
);
4422 cgroup_d_remove_dir(d
);
4425 set_bit(CGRP_RELEASABLE
, &parent
->flags
);
4426 check_for_release(parent
);
4429 * Unregister events and notify userspace.
4430 * Notify userspace about cgroup removing only after rmdir of cgroup
4431 * directory to avoid race between userspace and kernelspace.
4433 spin_lock(&cgrp
->event_list_lock
);
4434 list_for_each_entry_safe(event
, tmp
, &cgrp
->event_list
, list
) {
4435 list_del_init(&event
->list
);
4436 schedule_work(&event
->remove
);
4438 spin_unlock(&cgrp
->event_list_lock
);
4443 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
)
4447 mutex_lock(&cgroup_mutex
);
4448 ret
= cgroup_destroy_locked(dentry
->d_fsdata
);
4449 mutex_unlock(&cgroup_mutex
);
4454 static void __init_or_module
cgroup_init_cftsets(struct cgroup_subsys
*ss
)
4456 INIT_LIST_HEAD(&ss
->cftsets
);
4459 * base_cftset is embedded in subsys itself, no need to worry about
4462 if (ss
->base_cftypes
) {
4463 ss
->base_cftset
.cfts
= ss
->base_cftypes
;
4464 list_add_tail(&ss
->base_cftset
.node
, &ss
->cftsets
);
4468 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
)
4470 struct cgroup_subsys_state
*css
;
4472 printk(KERN_INFO
"Initializing cgroup subsys %s\n", ss
->name
);
4474 mutex_lock(&cgroup_mutex
);
4476 /* init base cftset */
4477 cgroup_init_cftsets(ss
);
4479 /* Create the top cgroup state for this subsystem */
4480 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
4481 ss
->root
= &rootnode
;
4482 css
= ss
->css_alloc(dummytop
);
4483 /* We don't handle early failures gracefully */
4484 BUG_ON(IS_ERR(css
));
4485 init_cgroup_css(css
, ss
, dummytop
);
4487 /* Update the init_css_set to contain a subsys
4488 * pointer to this state - since the subsystem is
4489 * newly registered, all tasks and hence the
4490 * init_css_set is in the subsystem's top cgroup. */
4491 init_css_set
.subsys
[ss
->subsys_id
] = css
;
4493 need_forkexit_callback
|= ss
->fork
|| ss
->exit
;
4495 /* At system boot, before all subsystems have been
4496 * registered, no tasks have been forked, so we don't
4497 * need to invoke fork callbacks here. */
4498 BUG_ON(!list_empty(&init_task
.tasks
));
4500 BUG_ON(online_css(ss
, dummytop
));
4502 mutex_unlock(&cgroup_mutex
);
4504 /* this function shouldn't be used with modular subsystems, since they
4505 * need to register a subsys_id, among other things */
4510 * cgroup_load_subsys: load and register a modular subsystem at runtime
4511 * @ss: the subsystem to load
4513 * This function should be called in a modular subsystem's initcall. If the
4514 * subsystem is built as a module, it will be assigned a new subsys_id and set
4515 * up for use. If the subsystem is built-in anyway, work is delegated to the
4516 * simpler cgroup_init_subsys.
4518 int __init_or_module
cgroup_load_subsys(struct cgroup_subsys
*ss
)
4520 struct cgroup_subsys_state
*css
;
4522 struct hlist_node
*tmp
;
4523 struct css_set
*cset
;
4526 /* check name and function validity */
4527 if (ss
->name
== NULL
|| strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
||
4528 ss
->css_alloc
== NULL
|| ss
->css_free
== NULL
)
4532 * we don't support callbacks in modular subsystems. this check is
4533 * before the ss->module check for consistency; a subsystem that could
4534 * be a module should still have no callbacks even if the user isn't
4535 * compiling it as one.
4537 if (ss
->fork
|| ss
->exit
)
4541 * an optionally modular subsystem is built-in: we want to do nothing,
4542 * since cgroup_init_subsys will have already taken care of it.
4544 if (ss
->module
== NULL
) {
4545 /* a sanity check */
4546 BUG_ON(subsys
[ss
->subsys_id
] != ss
);
4550 /* init base cftset */
4551 cgroup_init_cftsets(ss
);
4553 mutex_lock(&cgroup_mutex
);
4554 subsys
[ss
->subsys_id
] = ss
;
4557 * no ss->css_alloc seems to need anything important in the ss
4558 * struct, so this can happen first (i.e. before the rootnode
4561 css
= ss
->css_alloc(dummytop
);
4563 /* failure case - need to deassign the subsys[] slot. */
4564 subsys
[ss
->subsys_id
] = NULL
;
4565 mutex_unlock(&cgroup_mutex
);
4566 return PTR_ERR(css
);
4569 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
4570 ss
->root
= &rootnode
;
4572 /* our new subsystem will be attached to the dummy hierarchy. */
4573 init_cgroup_css(css
, ss
, dummytop
);
4574 /* init_idr must be after init_cgroup_css because it sets css->id. */
4576 ret
= cgroup_init_idr(ss
, css
);
4582 * Now we need to entangle the css into the existing css_sets. unlike
4583 * in cgroup_init_subsys, there are now multiple css_sets, so each one
4584 * will need a new pointer to it; done by iterating the css_set_table.
4585 * furthermore, modifying the existing css_sets will corrupt the hash
4586 * table state, so each changed css_set will need its hash recomputed.
4587 * this is all done under the css_set_lock.
4589 write_lock(&css_set_lock
);
4590 hash_for_each_safe(css_set_table
, i
, tmp
, cset
, hlist
) {
4591 /* skip entries that we already rehashed */
4592 if (cset
->subsys
[ss
->subsys_id
])
4594 /* remove existing entry */
4595 hash_del(&cset
->hlist
);
4597 cset
->subsys
[ss
->subsys_id
] = css
;
4598 /* recompute hash and restore entry */
4599 key
= css_set_hash(cset
->subsys
);
4600 hash_add(css_set_table
, &cset
->hlist
, key
);
4602 write_unlock(&css_set_lock
);
4604 ret
= online_css(ss
, dummytop
);
4609 mutex_unlock(&cgroup_mutex
);
4613 mutex_unlock(&cgroup_mutex
);
4614 /* @ss can't be mounted here as try_module_get() would fail */
4615 cgroup_unload_subsys(ss
);
4618 EXPORT_SYMBOL_GPL(cgroup_load_subsys
);
4621 * cgroup_unload_subsys: unload a modular subsystem
4622 * @ss: the subsystem to unload
4624 * This function should be called in a modular subsystem's exitcall. When this
4625 * function is invoked, the refcount on the subsystem's module will be 0, so
4626 * the subsystem will not be attached to any hierarchy.
4628 void cgroup_unload_subsys(struct cgroup_subsys
*ss
)
4630 struct cgrp_cset_link
*link
;
4632 BUG_ON(ss
->module
== NULL
);
4635 * we shouldn't be called if the subsystem is in use, and the use of
4636 * try_module_get in parse_cgroupfs_options should ensure that it
4637 * doesn't start being used while we're killing it off.
4639 BUG_ON(ss
->root
!= &rootnode
);
4641 mutex_lock(&cgroup_mutex
);
4643 offline_css(ss
, dummytop
);
4646 idr_destroy(&ss
->idr
);
4648 /* deassign the subsys_id */
4649 subsys
[ss
->subsys_id
] = NULL
;
4651 /* remove subsystem from rootnode's list of subsystems */
4652 list_del_init(&ss
->sibling
);
4655 * disentangle the css from all css_sets attached to the dummytop. as
4656 * in loading, we need to pay our respects to the hashtable gods.
4658 write_lock(&css_set_lock
);
4659 list_for_each_entry(link
, &dummytop
->cset_links
, cset_link
) {
4660 struct css_set
*cset
= link
->cset
;
4663 hash_del(&cset
->hlist
);
4664 cset
->subsys
[ss
->subsys_id
] = NULL
;
4665 key
= css_set_hash(cset
->subsys
);
4666 hash_add(css_set_table
, &cset
->hlist
, key
);
4668 write_unlock(&css_set_lock
);
4671 * remove subsystem's css from the dummytop and free it - need to
4672 * free before marking as null because ss->css_free needs the
4673 * cgrp->subsys pointer to find their state. note that this also
4674 * takes care of freeing the css_id.
4676 ss
->css_free(dummytop
);
4677 dummytop
->subsys
[ss
->subsys_id
] = NULL
;
4679 mutex_unlock(&cgroup_mutex
);
4681 EXPORT_SYMBOL_GPL(cgroup_unload_subsys
);
4684 * cgroup_init_early - cgroup initialization at system boot
4686 * Initialize cgroups at system boot, and initialize any
4687 * subsystems that request early init.
4689 int __init
cgroup_init_early(void)
4692 atomic_set(&init_css_set
.refcount
, 1);
4693 INIT_LIST_HEAD(&init_css_set
.cgrp_links
);
4694 INIT_LIST_HEAD(&init_css_set
.tasks
);
4695 INIT_HLIST_NODE(&init_css_set
.hlist
);
4697 init_cgroup_root(&rootnode
);
4699 init_task
.cgroups
= &init_css_set
;
4701 init_cgrp_cset_link
.cset
= &init_css_set
;
4702 init_cgrp_cset_link
.cgrp
= dummytop
;
4703 list_add(&init_cgrp_cset_link
.cset_link
, &rootnode
.top_cgroup
.cset_links
);
4704 list_add(&init_cgrp_cset_link
.cgrp_link
, &init_css_set
.cgrp_links
);
4706 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4707 struct cgroup_subsys
*ss
= subsys
[i
];
4709 /* at bootup time, we don't worry about modular subsystems */
4710 if (!ss
|| ss
->module
)
4714 BUG_ON(strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
);
4715 BUG_ON(!ss
->css_alloc
);
4716 BUG_ON(!ss
->css_free
);
4717 if (ss
->subsys_id
!= i
) {
4718 printk(KERN_ERR
"cgroup: Subsys %s id == %d\n",
4719 ss
->name
, ss
->subsys_id
);
4724 cgroup_init_subsys(ss
);
4730 * cgroup_init - cgroup initialization
4732 * Register cgroup filesystem and /proc file, and initialize
4733 * any subsystems that didn't request early init.
4735 int __init
cgroup_init(void)
4741 err
= bdi_init(&cgroup_backing_dev_info
);
4745 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4746 struct cgroup_subsys
*ss
= subsys
[i
];
4748 /* at bootup time, we don't worry about modular subsystems */
4749 if (!ss
|| ss
->module
)
4751 if (!ss
->early_init
)
4752 cgroup_init_subsys(ss
);
4754 cgroup_init_idr(ss
, init_css_set
.subsys
[ss
->subsys_id
]);
4757 /* Add init_css_set to the hash table */
4758 key
= css_set_hash(init_css_set
.subsys
);
4759 hash_add(css_set_table
, &init_css_set
.hlist
, key
);
4761 /* allocate id for the dummy hierarchy */
4762 mutex_lock(&cgroup_mutex
);
4763 mutex_lock(&cgroup_root_mutex
);
4765 BUG_ON(cgroup_init_root_id(&rootnode
));
4767 mutex_unlock(&cgroup_root_mutex
);
4768 mutex_unlock(&cgroup_mutex
);
4770 cgroup_kobj
= kobject_create_and_add("cgroup", fs_kobj
);
4776 err
= register_filesystem(&cgroup_fs_type
);
4778 kobject_put(cgroup_kobj
);
4782 proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
);
4786 bdi_destroy(&cgroup_backing_dev_info
);
4792 * proc_cgroup_show()
4793 * - Print task's cgroup paths into seq_file, one line for each hierarchy
4794 * - Used for /proc/<pid>/cgroup.
4795 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
4796 * doesn't really matter if tsk->cgroup changes after we read it,
4797 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
4798 * anyway. No need to check that tsk->cgroup != NULL, thanks to
4799 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
4800 * cgroup to top_cgroup.
4803 /* TODO: Use a proper seq_file iterator */
4804 int proc_cgroup_show(struct seq_file
*m
, void *v
)
4807 struct task_struct
*tsk
;
4810 struct cgroupfs_root
*root
;
4813 buf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
4819 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
4825 mutex_lock(&cgroup_mutex
);
4827 for_each_active_root(root
) {
4828 struct cgroup_subsys
*ss
;
4829 struct cgroup
*cgrp
;
4832 seq_printf(m
, "%d:", root
->hierarchy_id
);
4833 for_each_subsys(root
, ss
)
4834 seq_printf(m
, "%s%s", count
++ ? "," : "", ss
->name
);
4835 if (strlen(root
->name
))
4836 seq_printf(m
, "%sname=%s", count
? "," : "",
4839 cgrp
= task_cgroup_from_root(tsk
, root
);
4840 retval
= cgroup_path(cgrp
, buf
, PAGE_SIZE
);
4848 mutex_unlock(&cgroup_mutex
);
4849 put_task_struct(tsk
);
4856 /* Display information about each subsystem and each hierarchy */
4857 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
4861 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
4863 * ideally we don't want subsystems moving around while we do this.
4864 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
4865 * subsys/hierarchy state.
4867 mutex_lock(&cgroup_mutex
);
4868 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4869 struct cgroup_subsys
*ss
= subsys
[i
];
4872 seq_printf(m
, "%s\t%d\t%d\t%d\n",
4873 ss
->name
, ss
->root
->hierarchy_id
,
4874 ss
->root
->number_of_cgroups
, !ss
->disabled
);
4876 mutex_unlock(&cgroup_mutex
);
4880 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
4882 return single_open(file
, proc_cgroupstats_show
, NULL
);
4885 static const struct file_operations proc_cgroupstats_operations
= {
4886 .open
= cgroupstats_open
,
4888 .llseek
= seq_lseek
,
4889 .release
= single_release
,
4893 * cgroup_fork - attach newly forked task to its parents cgroup.
4894 * @child: pointer to task_struct of forking parent process.
4896 * Description: A task inherits its parent's cgroup at fork().
4898 * A pointer to the shared css_set was automatically copied in
4899 * fork.c by dup_task_struct(). However, we ignore that copy, since
4900 * it was not made under the protection of RCU or cgroup_mutex, so
4901 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
4902 * have already changed current->cgroups, allowing the previously
4903 * referenced cgroup group to be removed and freed.
4905 * At the point that cgroup_fork() is called, 'current' is the parent
4906 * task, and the passed argument 'child' points to the child task.
4908 void cgroup_fork(struct task_struct
*child
)
4911 child
->cgroups
= current
->cgroups
;
4912 get_css_set(child
->cgroups
);
4913 task_unlock(current
);
4914 INIT_LIST_HEAD(&child
->cg_list
);
4918 * cgroup_post_fork - called on a new task after adding it to the task list
4919 * @child: the task in question
4921 * Adds the task to the list running through its css_set if necessary and
4922 * call the subsystem fork() callbacks. Has to be after the task is
4923 * visible on the task list in case we race with the first call to
4924 * cgroup_iter_start() - to guarantee that the new task ends up on its
4927 void cgroup_post_fork(struct task_struct
*child
)
4932 * use_task_css_set_links is set to 1 before we walk the tasklist
4933 * under the tasklist_lock and we read it here after we added the child
4934 * to the tasklist under the tasklist_lock as well. If the child wasn't
4935 * yet in the tasklist when we walked through it from
4936 * cgroup_enable_task_cg_lists(), then use_task_css_set_links value
4937 * should be visible now due to the paired locking and barriers implied
4938 * by LOCK/UNLOCK: it is written before the tasklist_lock unlock
4939 * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
4942 if (use_task_css_set_links
) {
4943 write_lock(&css_set_lock
);
4945 if (list_empty(&child
->cg_list
))
4946 list_add(&child
->cg_list
, &child
->cgroups
->tasks
);
4948 write_unlock(&css_set_lock
);
4952 * Call ss->fork(). This must happen after @child is linked on
4953 * css_set; otherwise, @child might change state between ->fork()
4954 * and addition to css_set.
4956 if (need_forkexit_callback
) {
4958 * fork/exit callbacks are supported only for builtin
4959 * subsystems, and the builtin section of the subsys
4960 * array is immutable, so we don't need to lock the
4961 * subsys array here. On the other hand, modular section
4962 * of the array can be freed at module unload, so we
4965 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
4966 struct cgroup_subsys
*ss
= subsys
[i
];
4975 * cgroup_exit - detach cgroup from exiting task
4976 * @tsk: pointer to task_struct of exiting process
4977 * @run_callback: run exit callbacks?
4979 * Description: Detach cgroup from @tsk and release it.
4981 * Note that cgroups marked notify_on_release force every task in
4982 * them to take the global cgroup_mutex mutex when exiting.
4983 * This could impact scaling on very large systems. Be reluctant to
4984 * use notify_on_release cgroups where very high task exit scaling
4985 * is required on large systems.
4987 * the_top_cgroup_hack:
4989 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
4991 * We call cgroup_exit() while the task is still competent to
4992 * handle notify_on_release(), then leave the task attached to the
4993 * root cgroup in each hierarchy for the remainder of its exit.
4995 * To do this properly, we would increment the reference count on
4996 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
4997 * code we would add a second cgroup function call, to drop that
4998 * reference. This would just create an unnecessary hot spot on
4999 * the top_cgroup reference count, to no avail.
5001 * Normally, holding a reference to a cgroup without bumping its
5002 * count is unsafe. The cgroup could go away, or someone could
5003 * attach us to a different cgroup, decrementing the count on
5004 * the first cgroup that we never incremented. But in this case,
5005 * top_cgroup isn't going away, and either task has PF_EXITING set,
5006 * which wards off any cgroup_attach_task() attempts, or task is a failed
5007 * fork, never visible to cgroup_attach_task.
5009 void cgroup_exit(struct task_struct
*tsk
, int run_callbacks
)
5011 struct css_set
*cset
;
5015 * Unlink from the css_set task list if necessary.
5016 * Optimistically check cg_list before taking
5019 if (!list_empty(&tsk
->cg_list
)) {
5020 write_lock(&css_set_lock
);
5021 if (!list_empty(&tsk
->cg_list
))
5022 list_del_init(&tsk
->cg_list
);
5023 write_unlock(&css_set_lock
);
5026 /* Reassign the task to the init_css_set. */
5028 cset
= tsk
->cgroups
;
5029 tsk
->cgroups
= &init_css_set
;
5031 if (run_callbacks
&& need_forkexit_callback
) {
5033 * fork/exit callbacks are supported only for builtin
5034 * subsystems, see cgroup_post_fork() for details.
5036 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
5037 struct cgroup_subsys
*ss
= subsys
[i
];
5040 struct cgroup
*old_cgrp
=
5041 rcu_dereference_raw(cset
->subsys
[i
])->cgroup
;
5042 struct cgroup
*cgrp
= task_cgroup(tsk
, i
);
5043 ss
->exit(cgrp
, old_cgrp
, tsk
);
5049 put_css_set_taskexit(cset
);
5052 static void check_for_release(struct cgroup
*cgrp
)
5054 /* All of these checks rely on RCU to keep the cgroup
5055 * structure alive */
5056 if (cgroup_is_releasable(cgrp
) &&
5057 !atomic_read(&cgrp
->count
) && list_empty(&cgrp
->children
)) {
5059 * Control Group is currently removeable. If it's not
5060 * already queued for a userspace notification, queue
5063 int need_schedule_work
= 0;
5065 raw_spin_lock(&release_list_lock
);
5066 if (!cgroup_is_removed(cgrp
) &&
5067 list_empty(&cgrp
->release_list
)) {
5068 list_add(&cgrp
->release_list
, &release_list
);
5069 need_schedule_work
= 1;
5071 raw_spin_unlock(&release_list_lock
);
5072 if (need_schedule_work
)
5073 schedule_work(&release_agent_work
);
5077 /* Caller must verify that the css is not for root cgroup */
5078 bool __css_tryget(struct cgroup_subsys_state
*css
)
5083 v
= css_refcnt(css
);
5084 t
= atomic_cmpxchg(&css
->refcnt
, v
, v
+ 1);
5092 EXPORT_SYMBOL_GPL(__css_tryget
);
5094 /* Caller must verify that the css is not for root cgroup */
5095 void __css_put(struct cgroup_subsys_state
*css
)
5099 v
= css_unbias_refcnt(atomic_dec_return(&css
->refcnt
));
5101 schedule_work(&css
->dput_work
);
5103 EXPORT_SYMBOL_GPL(__css_put
);
5106 * Notify userspace when a cgroup is released, by running the
5107 * configured release agent with the name of the cgroup (path
5108 * relative to the root of cgroup file system) as the argument.
5110 * Most likely, this user command will try to rmdir this cgroup.
5112 * This races with the possibility that some other task will be
5113 * attached to this cgroup before it is removed, or that some other
5114 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
5115 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
5116 * unused, and this cgroup will be reprieved from its death sentence,
5117 * to continue to serve a useful existence. Next time it's released,
5118 * we will get notified again, if it still has 'notify_on_release' set.
5120 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
5121 * means only wait until the task is successfully execve()'d. The
5122 * separate release agent task is forked by call_usermodehelper(),
5123 * then control in this thread returns here, without waiting for the
5124 * release agent task. We don't bother to wait because the caller of
5125 * this routine has no use for the exit status of the release agent
5126 * task, so no sense holding our caller up for that.
5128 static void cgroup_release_agent(struct work_struct
*work
)
5130 BUG_ON(work
!= &release_agent_work
);
5131 mutex_lock(&cgroup_mutex
);
5132 raw_spin_lock(&release_list_lock
);
5133 while (!list_empty(&release_list
)) {
5134 char *argv
[3], *envp
[3];
5136 char *pathbuf
= NULL
, *agentbuf
= NULL
;
5137 struct cgroup
*cgrp
= list_entry(release_list
.next
,
5140 list_del_init(&cgrp
->release_list
);
5141 raw_spin_unlock(&release_list_lock
);
5142 pathbuf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
5145 if (cgroup_path(cgrp
, pathbuf
, PAGE_SIZE
) < 0)
5147 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
5152 argv
[i
++] = agentbuf
;
5153 argv
[i
++] = pathbuf
;
5157 /* minimal command environment */
5158 envp
[i
++] = "HOME=/";
5159 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
5162 /* Drop the lock while we invoke the usermode helper,
5163 * since the exec could involve hitting disk and hence
5164 * be a slow process */
5165 mutex_unlock(&cgroup_mutex
);
5166 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
5167 mutex_lock(&cgroup_mutex
);
5171 raw_spin_lock(&release_list_lock
);
5173 raw_spin_unlock(&release_list_lock
);
5174 mutex_unlock(&cgroup_mutex
);
5177 static int __init
cgroup_disable(char *str
)
5182 while ((token
= strsep(&str
, ",")) != NULL
) {
5185 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
5186 struct cgroup_subsys
*ss
= subsys
[i
];
5189 * cgroup_disable, being at boot time, can't
5190 * know about module subsystems, so we don't
5193 if (!ss
|| ss
->module
)
5196 if (!strcmp(token
, ss
->name
)) {
5198 printk(KERN_INFO
"Disabling %s control group"
5199 " subsystem\n", ss
->name
);
5206 __setup("cgroup_disable=", cgroup_disable
);
5209 * Functons for CSS ID.
5213 *To get ID other than 0, this should be called when !cgroup_is_removed().
5215 unsigned short css_id(struct cgroup_subsys_state
*css
)
5217 struct css_id
*cssid
;
5220 * This css_id() can return correct value when somone has refcnt
5221 * on this or this is under rcu_read_lock(). Once css->id is allocated,
5222 * it's unchanged until freed.
5224 cssid
= rcu_dereference_check(css
->id
, css_refcnt(css
));
5230 EXPORT_SYMBOL_GPL(css_id
);
5233 * css_is_ancestor - test "root" css is an ancestor of "child"
5234 * @child: the css to be tested.
5235 * @root: the css supporsed to be an ancestor of the child.
5237 * Returns true if "root" is an ancestor of "child" in its hierarchy. Because
5238 * this function reads css->id, the caller must hold rcu_read_lock().
5239 * But, considering usual usage, the csses should be valid objects after test.
5240 * Assuming that the caller will do some action to the child if this returns
5241 * returns true, the caller must take "child";s reference count.
5242 * If "child" is valid object and this returns true, "root" is valid, too.
5245 bool css_is_ancestor(struct cgroup_subsys_state
*child
,
5246 const struct cgroup_subsys_state
*root
)
5248 struct css_id
*child_id
;
5249 struct css_id
*root_id
;
5251 child_id
= rcu_dereference(child
->id
);
5254 root_id
= rcu_dereference(root
->id
);
5257 if (child_id
->depth
< root_id
->depth
)
5259 if (child_id
->stack
[root_id
->depth
] != root_id
->id
)
5264 void free_css_id(struct cgroup_subsys
*ss
, struct cgroup_subsys_state
*css
)
5266 struct css_id
*id
= css
->id
;
5267 /* When this is called before css_id initialization, id can be NULL */
5271 BUG_ON(!ss
->use_id
);
5273 rcu_assign_pointer(id
->css
, NULL
);
5274 rcu_assign_pointer(css
->id
, NULL
);
5275 spin_lock(&ss
->id_lock
);
5276 idr_remove(&ss
->idr
, id
->id
);
5277 spin_unlock(&ss
->id_lock
);
5278 kfree_rcu(id
, rcu_head
);
5280 EXPORT_SYMBOL_GPL(free_css_id
);
5283 * This is called by init or create(). Then, calls to this function are
5284 * always serialized (By cgroup_mutex() at create()).
5287 static struct css_id
*get_new_cssid(struct cgroup_subsys
*ss
, int depth
)
5289 struct css_id
*newid
;
5292 BUG_ON(!ss
->use_id
);
5294 size
= sizeof(*newid
) + sizeof(unsigned short) * (depth
+ 1);
5295 newid
= kzalloc(size
, GFP_KERNEL
);
5297 return ERR_PTR(-ENOMEM
);
5299 idr_preload(GFP_KERNEL
);
5300 spin_lock(&ss
->id_lock
);
5301 /* Don't use 0. allocates an ID of 1-65535 */
5302 ret
= idr_alloc(&ss
->idr
, newid
, 1, CSS_ID_MAX
+ 1, GFP_NOWAIT
);
5303 spin_unlock(&ss
->id_lock
);
5306 /* Returns error when there are no free spaces for new ID.*/
5311 newid
->depth
= depth
;
5315 return ERR_PTR(ret
);
5319 static int __init_or_module
cgroup_init_idr(struct cgroup_subsys
*ss
,
5320 struct cgroup_subsys_state
*rootcss
)
5322 struct css_id
*newid
;
5324 spin_lock_init(&ss
->id_lock
);
5327 newid
= get_new_cssid(ss
, 0);
5329 return PTR_ERR(newid
);
5331 newid
->stack
[0] = newid
->id
;
5332 newid
->css
= rootcss
;
5333 rootcss
->id
= newid
;
5337 static int alloc_css_id(struct cgroup_subsys
*ss
, struct cgroup
*parent
,
5338 struct cgroup
*child
)
5340 int subsys_id
, i
, depth
= 0;
5341 struct cgroup_subsys_state
*parent_css
, *child_css
;
5342 struct css_id
*child_id
, *parent_id
;
5344 subsys_id
= ss
->subsys_id
;
5345 parent_css
= parent
->subsys
[subsys_id
];
5346 child_css
= child
->subsys
[subsys_id
];
5347 parent_id
= parent_css
->id
;
5348 depth
= parent_id
->depth
+ 1;
5350 child_id
= get_new_cssid(ss
, depth
);
5351 if (IS_ERR(child_id
))
5352 return PTR_ERR(child_id
);
5354 for (i
= 0; i
< depth
; i
++)
5355 child_id
->stack
[i
] = parent_id
->stack
[i
];
5356 child_id
->stack
[depth
] = child_id
->id
;
5358 * child_id->css pointer will be set after this cgroup is available
5359 * see cgroup_populate_dir()
5361 rcu_assign_pointer(child_css
->id
, child_id
);
5367 * css_lookup - lookup css by id
5368 * @ss: cgroup subsys to be looked into.
5371 * Returns pointer to cgroup_subsys_state if there is valid one with id.
5372 * NULL if not. Should be called under rcu_read_lock()
5374 struct cgroup_subsys_state
*css_lookup(struct cgroup_subsys
*ss
, int id
)
5376 struct css_id
*cssid
= NULL
;
5378 BUG_ON(!ss
->use_id
);
5379 cssid
= idr_find(&ss
->idr
, id
);
5381 if (unlikely(!cssid
))
5384 return rcu_dereference(cssid
->css
);
5386 EXPORT_SYMBOL_GPL(css_lookup
);
5389 * get corresponding css from file open on cgroupfs directory
5391 struct cgroup_subsys_state
*cgroup_css_from_dir(struct file
*f
, int id
)
5393 struct cgroup
*cgrp
;
5394 struct inode
*inode
;
5395 struct cgroup_subsys_state
*css
;
5397 inode
= file_inode(f
);
5398 /* check in cgroup filesystem dir */
5399 if (inode
->i_op
!= &cgroup_dir_inode_operations
)
5400 return ERR_PTR(-EBADF
);
5402 if (id
< 0 || id
>= CGROUP_SUBSYS_COUNT
)
5403 return ERR_PTR(-EINVAL
);
5406 cgrp
= __d_cgrp(f
->f_dentry
);
5407 css
= cgrp
->subsys
[id
];
5408 return css
? css
: ERR_PTR(-ENOENT
);
5411 #ifdef CONFIG_CGROUP_DEBUG
5412 static struct cgroup_subsys_state
*debug_css_alloc(struct cgroup
*cont
)
5414 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
5417 return ERR_PTR(-ENOMEM
);
5422 static void debug_css_free(struct cgroup
*cont
)
5424 kfree(cont
->subsys
[debug_subsys_id
]);
5427 static u64
cgroup_refcount_read(struct cgroup
*cont
, struct cftype
*cft
)
5429 return atomic_read(&cont
->count
);
5432 static u64
debug_taskcount_read(struct cgroup
*cont
, struct cftype
*cft
)
5434 return cgroup_task_count(cont
);
5437 static u64
current_css_set_read(struct cgroup
*cont
, struct cftype
*cft
)
5439 return (u64
)(unsigned long)current
->cgroups
;
5442 static u64
current_css_set_refcount_read(struct cgroup
*cont
,
5448 count
= atomic_read(¤t
->cgroups
->refcount
);
5453 static int current_css_set_cg_links_read(struct cgroup
*cont
,
5455 struct seq_file
*seq
)
5457 struct cgrp_cset_link
*link
;
5458 struct css_set
*cset
;
5460 read_lock(&css_set_lock
);
5462 cset
= rcu_dereference(current
->cgroups
);
5463 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
5464 struct cgroup
*c
= link
->cgrp
;
5468 name
= c
->dentry
->d_name
.name
;
5471 seq_printf(seq
, "Root %d group %s\n",
5472 c
->root
->hierarchy_id
, name
);
5475 read_unlock(&css_set_lock
);
5479 #define MAX_TASKS_SHOWN_PER_CSS 25
5480 static int cgroup_css_links_read(struct cgroup
*cont
,
5482 struct seq_file
*seq
)
5484 struct cgrp_cset_link
*link
;
5486 read_lock(&css_set_lock
);
5487 list_for_each_entry(link
, &cont
->cset_links
, cset_link
) {
5488 struct css_set
*cset
= link
->cset
;
5489 struct task_struct
*task
;
5491 seq_printf(seq
, "css_set %p\n", cset
);
5492 list_for_each_entry(task
, &cset
->tasks
, cg_list
) {
5493 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
) {
5494 seq_puts(seq
, " ...\n");
5497 seq_printf(seq
, " task %d\n",
5498 task_pid_vnr(task
));
5502 read_unlock(&css_set_lock
);
5506 static u64
releasable_read(struct cgroup
*cgrp
, struct cftype
*cft
)
5508 return test_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
5511 static struct cftype debug_files
[] = {
5513 .name
= "cgroup_refcount",
5514 .read_u64
= cgroup_refcount_read
,
5517 .name
= "taskcount",
5518 .read_u64
= debug_taskcount_read
,
5522 .name
= "current_css_set",
5523 .read_u64
= current_css_set_read
,
5527 .name
= "current_css_set_refcount",
5528 .read_u64
= current_css_set_refcount_read
,
5532 .name
= "current_css_set_cg_links",
5533 .read_seq_string
= current_css_set_cg_links_read
,
5537 .name
= "cgroup_css_links",
5538 .read_seq_string
= cgroup_css_links_read
,
5542 .name
= "releasable",
5543 .read_u64
= releasable_read
,
5549 struct cgroup_subsys debug_subsys
= {
5551 .css_alloc
= debug_css_alloc
,
5552 .css_free
= debug_css_free
,
5553 .subsys_id
= debug_subsys_id
,
5554 .base_cftypes
= debug_files
,
5556 #endif /* CONFIG_CGROUP_DEBUG */