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>
34 #include <linux/init_task.h>
35 #include <linux/kernel.h>
36 #include <linux/list.h>
38 #include <linux/mutex.h>
39 #include <linux/mount.h>
40 #include <linux/pagemap.h>
41 #include <linux/proc_fs.h>
42 #include <linux/rcupdate.h>
43 #include <linux/sched.h>
44 #include <linux/backing-dev.h>
45 #include <linux/seq_file.h>
46 #include <linux/slab.h>
47 #include <linux/magic.h>
48 #include <linux/spinlock.h>
49 #include <linux/string.h>
50 #include <linux/sort.h>
51 #include <linux/kmod.h>
52 #include <linux/module.h>
53 #include <linux/delayacct.h>
54 #include <linux/cgroupstats.h>
55 #include <linux/hash.h>
56 #include <linux/namei.h>
57 #include <linux/pid_namespace.h>
58 #include <linux/idr.h>
59 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
60 #include <linux/eventfd.h>
61 #include <linux/poll.h>
62 #include <linux/flex_array.h> /* used in cgroup_attach_proc */
63 #include <linux/kthread.h>
65 #include <linux/atomic.h>
67 /* css deactivation bias, makes css->refcnt negative to deny new trygets */
68 #define CSS_DEACT_BIAS INT_MIN
71 * cgroup_mutex is the master lock. Any modification to cgroup or its
72 * hierarchy must be performed while holding it.
74 * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify
75 * cgroupfs_root of any cgroup hierarchy - subsys list, flags,
76 * release_agent_path and so on. Modifying requires both cgroup_mutex and
77 * cgroup_root_mutex. Readers can acquire either of the two. This is to
78 * break the following locking order cycle.
80 * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem
81 * B. namespace_sem -> cgroup_mutex
83 * B happens only through cgroup_show_options() and using cgroup_root_mutex
86 static DEFINE_MUTEX(cgroup_mutex
);
87 static DEFINE_MUTEX(cgroup_root_mutex
);
90 * Generate an array of cgroup subsystem pointers. At boot time, this is
91 * populated with the built in subsystems, and modular subsystems are
92 * registered after that. The mutable section of this array is protected by
95 #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
96 #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
97 static struct cgroup_subsys
*subsys
[CGROUP_SUBSYS_COUNT
] = {
98 #include <linux/cgroup_subsys.h>
101 #define MAX_CGROUP_ROOT_NAMELEN 64
104 * A cgroupfs_root represents the root of a cgroup hierarchy,
105 * and may be associated with a superblock to form an active
108 struct cgroupfs_root
{
109 struct super_block
*sb
;
112 * The bitmask of subsystems intended to be attached to this
115 unsigned long subsys_mask
;
117 /* Unique id for this hierarchy. */
120 /* The bitmask of subsystems currently attached to this hierarchy */
121 unsigned long actual_subsys_mask
;
123 /* A list running through the attached subsystems */
124 struct list_head subsys_list
;
126 /* The root cgroup for this hierarchy */
127 struct cgroup top_cgroup
;
129 /* Tracks how many cgroups are currently defined in hierarchy.*/
130 int number_of_cgroups
;
132 /* A list running through the active hierarchies */
133 struct list_head root_list
;
135 /* All cgroups on this root, cgroup_mutex protected */
136 struct list_head allcg_list
;
138 /* Hierarchy-specific flags */
141 /* The path to use for release notifications. */
142 char release_agent_path
[PATH_MAX
];
144 /* The name for this hierarchy - may be empty */
145 char name
[MAX_CGROUP_ROOT_NAMELEN
];
149 * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
150 * subsystems that are otherwise unattached - it never has more than a
151 * single cgroup, and all tasks are part of that cgroup.
153 static struct cgroupfs_root rootnode
;
156 * cgroupfs file entry, pointed to from leaf dentry->d_fsdata.
159 struct list_head node
;
160 struct dentry
*dentry
;
165 * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
166 * cgroup_subsys->use_id != 0.
168 #define CSS_ID_MAX (65535)
171 * The css to which this ID points. This pointer is set to valid value
172 * after cgroup is populated. If cgroup is removed, this will be NULL.
173 * This pointer is expected to be RCU-safe because destroy()
174 * is called after synchronize_rcu(). But for safe use, css_tryget()
175 * should be used for avoiding race.
177 struct cgroup_subsys_state __rcu
*css
;
183 * Depth in hierarchy which this ID belongs to.
185 unsigned short depth
;
187 * ID is freed by RCU. (and lookup routine is RCU safe.)
189 struct rcu_head rcu_head
;
191 * Hierarchy of CSS ID belongs to.
193 unsigned short stack
[0]; /* Array of Length (depth+1) */
197 * cgroup_event represents events which userspace want to receive.
199 struct cgroup_event
{
201 * Cgroup which the event belongs to.
205 * Control file which the event associated.
209 * eventfd to signal userspace about the event.
211 struct eventfd_ctx
*eventfd
;
213 * Each of these stored in a list by the cgroup.
215 struct list_head list
;
217 * All fields below needed to unregister event when
218 * userspace closes eventfd.
221 wait_queue_head_t
*wqh
;
223 struct work_struct remove
;
226 /* The list of hierarchy roots */
228 static LIST_HEAD(roots
);
229 static int root_count
;
231 static DEFINE_IDA(hierarchy_ida
);
232 static int next_hierarchy_id
;
233 static DEFINE_SPINLOCK(hierarchy_id_lock
);
235 /* dummytop is a shorthand for the dummy hierarchy's top cgroup */
236 #define dummytop (&rootnode.top_cgroup)
238 /* This flag indicates whether tasks in the fork and exit paths should
239 * check for fork/exit handlers to call. This avoids us having to do
240 * extra work in the fork/exit path if none of the subsystems need to
243 static int need_forkexit_callback __read_mostly
;
245 static int cgroup_destroy_locked(struct cgroup
*cgrp
);
247 #ifdef CONFIG_PROVE_LOCKING
248 int cgroup_lock_is_held(void)
250 return lockdep_is_held(&cgroup_mutex
);
252 #else /* #ifdef CONFIG_PROVE_LOCKING */
253 int cgroup_lock_is_held(void)
255 return mutex_is_locked(&cgroup_mutex
);
257 #endif /* #else #ifdef CONFIG_PROVE_LOCKING */
259 EXPORT_SYMBOL_GPL(cgroup_lock_is_held
);
261 static int css_unbias_refcnt(int refcnt
)
263 return refcnt
>= 0 ? refcnt
: refcnt
- CSS_DEACT_BIAS
;
266 /* the current nr of refs, always >= 0 whether @css is deactivated or not */
267 static int css_refcnt(struct cgroup_subsys_state
*css
)
269 int v
= atomic_read(&css
->refcnt
);
271 return css_unbias_refcnt(v
);
274 /* convenient tests for these bits */
275 inline int cgroup_is_removed(const struct cgroup
*cgrp
)
277 return test_bit(CGRP_REMOVED
, &cgrp
->flags
);
280 /* bits in struct cgroupfs_root flags field */
282 ROOT_NOPREFIX
, /* mounted subsystems have no named prefix */
283 ROOT_XATTR
, /* supports extended attributes */
286 static int cgroup_is_releasable(const struct cgroup
*cgrp
)
289 (1 << CGRP_RELEASABLE
) |
290 (1 << CGRP_NOTIFY_ON_RELEASE
);
291 return (cgrp
->flags
& bits
) == bits
;
294 static int notify_on_release(const struct cgroup
*cgrp
)
296 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
300 * for_each_subsys() allows you to iterate on each subsystem attached to
301 * an active hierarchy
303 #define for_each_subsys(_root, _ss) \
304 list_for_each_entry(_ss, &_root->subsys_list, sibling)
306 /* for_each_active_root() allows you to iterate across the active hierarchies */
307 #define for_each_active_root(_root) \
308 list_for_each_entry(_root, &roots, root_list)
310 static inline struct cgroup
*__d_cgrp(struct dentry
*dentry
)
312 return dentry
->d_fsdata
;
315 static inline struct cfent
*__d_cfe(struct dentry
*dentry
)
317 return dentry
->d_fsdata
;
320 static inline struct cftype
*__d_cft(struct dentry
*dentry
)
322 return __d_cfe(dentry
)->type
;
325 /* the list of cgroups eligible for automatic release. Protected by
326 * release_list_lock */
327 static LIST_HEAD(release_list
);
328 static DEFINE_RAW_SPINLOCK(release_list_lock
);
329 static void cgroup_release_agent(struct work_struct
*work
);
330 static DECLARE_WORK(release_agent_work
, cgroup_release_agent
);
331 static void check_for_release(struct cgroup
*cgrp
);
333 /* Link structure for associating css_set objects with cgroups */
334 struct cg_cgroup_link
{
336 * List running through cg_cgroup_links associated with a
337 * cgroup, anchored on cgroup->css_sets
339 struct list_head cgrp_link_list
;
342 * List running through cg_cgroup_links pointing at a
343 * single css_set object, anchored on css_set->cg_links
345 struct list_head cg_link_list
;
349 /* The default css_set - used by init and its children prior to any
350 * hierarchies being mounted. It contains a pointer to the root state
351 * for each subsystem. Also used to anchor the list of css_sets. Not
352 * reference-counted, to improve performance when child cgroups
353 * haven't been created.
356 static struct css_set init_css_set
;
357 static struct cg_cgroup_link init_css_set_link
;
359 static int cgroup_init_idr(struct cgroup_subsys
*ss
,
360 struct cgroup_subsys_state
*css
);
362 /* css_set_lock protects the list of css_set objects, and the
363 * chain of tasks off each css_set. Nests outside task->alloc_lock
364 * due to cgroup_iter_start() */
365 static DEFINE_RWLOCK(css_set_lock
);
366 static int css_set_count
;
369 * hash table for cgroup groups. This improves the performance to find
370 * an existing css_set. This hash doesn't (currently) take into
371 * account cgroups in empty hierarchies.
373 #define CSS_SET_HASH_BITS 7
374 #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS)
375 static struct hlist_head css_set_table
[CSS_SET_TABLE_SIZE
];
377 static struct hlist_head
*css_set_hash(struct cgroup_subsys_state
*css
[])
381 unsigned long tmp
= 0UL;
383 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++)
384 tmp
+= (unsigned long)css
[i
];
385 tmp
= (tmp
>> 16) ^ tmp
;
387 index
= hash_long(tmp
, CSS_SET_HASH_BITS
);
389 return &css_set_table
[index
];
392 /* We don't maintain the lists running through each css_set to its
393 * task until after the first call to cgroup_iter_start(). This
394 * reduces the fork()/exit() overhead for people who have cgroups
395 * compiled into their kernel but not actually in use */
396 static int use_task_css_set_links __read_mostly
;
398 static void __put_css_set(struct css_set
*cg
, int taskexit
)
400 struct cg_cgroup_link
*link
;
401 struct cg_cgroup_link
*saved_link
;
403 * Ensure that the refcount doesn't hit zero while any readers
404 * can see it. Similar to atomic_dec_and_lock(), but for an
407 if (atomic_add_unless(&cg
->refcount
, -1, 1))
409 write_lock(&css_set_lock
);
410 if (!atomic_dec_and_test(&cg
->refcount
)) {
411 write_unlock(&css_set_lock
);
415 /* This css_set is dead. unlink it and release cgroup refcounts */
416 hlist_del(&cg
->hlist
);
419 list_for_each_entry_safe(link
, saved_link
, &cg
->cg_links
,
421 struct cgroup
*cgrp
= link
->cgrp
;
422 list_del(&link
->cg_link_list
);
423 list_del(&link
->cgrp_link_list
);
424 if (atomic_dec_and_test(&cgrp
->count
) &&
425 notify_on_release(cgrp
)) {
427 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
428 check_for_release(cgrp
);
434 write_unlock(&css_set_lock
);
435 kfree_rcu(cg
, rcu_head
);
439 * refcounted get/put for css_set objects
441 static inline void get_css_set(struct css_set
*cg
)
443 atomic_inc(&cg
->refcount
);
446 static inline void put_css_set(struct css_set
*cg
)
448 __put_css_set(cg
, 0);
451 static inline void put_css_set_taskexit(struct css_set
*cg
)
453 __put_css_set(cg
, 1);
457 * compare_css_sets - helper function for find_existing_css_set().
458 * @cg: candidate css_set being tested
459 * @old_cg: existing css_set for a task
460 * @new_cgrp: cgroup that's being entered by the task
461 * @template: desired set of css pointers in css_set (pre-calculated)
463 * Returns true if "cg" matches "old_cg" except for the hierarchy
464 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
466 static bool compare_css_sets(struct css_set
*cg
,
467 struct css_set
*old_cg
,
468 struct cgroup
*new_cgrp
,
469 struct cgroup_subsys_state
*template[])
471 struct list_head
*l1
, *l2
;
473 if (memcmp(template, cg
->subsys
, sizeof(cg
->subsys
))) {
474 /* Not all subsystems matched */
479 * Compare cgroup pointers in order to distinguish between
480 * different cgroups in heirarchies with no subsystems. We
481 * could get by with just this check alone (and skip the
482 * memcmp above) but on most setups the memcmp check will
483 * avoid the need for this more expensive check on almost all
488 l2
= &old_cg
->cg_links
;
490 struct cg_cgroup_link
*cgl1
, *cgl2
;
491 struct cgroup
*cg1
, *cg2
;
495 /* See if we reached the end - both lists are equal length. */
496 if (l1
== &cg
->cg_links
) {
497 BUG_ON(l2
!= &old_cg
->cg_links
);
500 BUG_ON(l2
== &old_cg
->cg_links
);
502 /* Locate the cgroups associated with these links. */
503 cgl1
= list_entry(l1
, struct cg_cgroup_link
, cg_link_list
);
504 cgl2
= list_entry(l2
, struct cg_cgroup_link
, cg_link_list
);
507 /* Hierarchies should be linked in the same order. */
508 BUG_ON(cg1
->root
!= cg2
->root
);
511 * If this hierarchy is the hierarchy of the cgroup
512 * that's changing, then we need to check that this
513 * css_set points to the new cgroup; if it's any other
514 * hierarchy, then this css_set should point to the
515 * same cgroup as the old css_set.
517 if (cg1
->root
== new_cgrp
->root
) {
529 * find_existing_css_set() is a helper for
530 * find_css_set(), and checks to see whether an existing
531 * css_set is suitable.
533 * oldcg: the cgroup group that we're using before the cgroup
536 * cgrp: the cgroup that we're moving into
538 * template: location in which to build the desired set of subsystem
539 * state objects for the new cgroup group
541 static struct css_set
*find_existing_css_set(
542 struct css_set
*oldcg
,
544 struct cgroup_subsys_state
*template[])
547 struct cgroupfs_root
*root
= cgrp
->root
;
548 struct hlist_head
*hhead
;
549 struct hlist_node
*node
;
553 * Build the set of subsystem state objects that we want to see in the
554 * new css_set. while subsystems can change globally, the entries here
555 * won't change, so no need for locking.
557 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
558 if (root
->subsys_mask
& (1UL << i
)) {
559 /* Subsystem is in this hierarchy. So we want
560 * the subsystem state from the new
562 template[i
] = cgrp
->subsys
[i
];
564 /* Subsystem is not in this hierarchy, so we
565 * don't want to change the subsystem state */
566 template[i
] = oldcg
->subsys
[i
];
570 hhead
= css_set_hash(template);
571 hlist_for_each_entry(cg
, node
, hhead
, hlist
) {
572 if (!compare_css_sets(cg
, oldcg
, cgrp
, template))
575 /* This css_set matches what we need */
579 /* No existing cgroup group matched */
583 static void free_cg_links(struct list_head
*tmp
)
585 struct cg_cgroup_link
*link
;
586 struct cg_cgroup_link
*saved_link
;
588 list_for_each_entry_safe(link
, saved_link
, tmp
, cgrp_link_list
) {
589 list_del(&link
->cgrp_link_list
);
595 * allocate_cg_links() allocates "count" cg_cgroup_link structures
596 * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
597 * success or a negative error
599 static int allocate_cg_links(int count
, struct list_head
*tmp
)
601 struct cg_cgroup_link
*link
;
604 for (i
= 0; i
< count
; i
++) {
605 link
= kmalloc(sizeof(*link
), GFP_KERNEL
);
610 list_add(&link
->cgrp_link_list
, tmp
);
616 * link_css_set - a helper function to link a css_set to a cgroup
617 * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()
618 * @cg: the css_set to be linked
619 * @cgrp: the destination cgroup
621 static void link_css_set(struct list_head
*tmp_cg_links
,
622 struct css_set
*cg
, struct cgroup
*cgrp
)
624 struct cg_cgroup_link
*link
;
626 BUG_ON(list_empty(tmp_cg_links
));
627 link
= list_first_entry(tmp_cg_links
, struct cg_cgroup_link
,
631 atomic_inc(&cgrp
->count
);
632 list_move(&link
->cgrp_link_list
, &cgrp
->css_sets
);
634 * Always add links to the tail of the list so that the list
635 * is sorted by order of hierarchy creation
637 list_add_tail(&link
->cg_link_list
, &cg
->cg_links
);
641 * find_css_set() takes an existing cgroup group and a
642 * cgroup object, and returns a css_set object that's
643 * equivalent to the old group, but with the given cgroup
644 * substituted into the appropriate hierarchy. Must be called with
647 static struct css_set
*find_css_set(
648 struct css_set
*oldcg
, struct cgroup
*cgrp
)
651 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
];
653 struct list_head tmp_cg_links
;
655 struct hlist_head
*hhead
;
656 struct cg_cgroup_link
*link
;
658 /* First see if we already have a cgroup group that matches
660 read_lock(&css_set_lock
);
661 res
= find_existing_css_set(oldcg
, cgrp
, template);
664 read_unlock(&css_set_lock
);
669 res
= kmalloc(sizeof(*res
), GFP_KERNEL
);
673 /* Allocate all the cg_cgroup_link objects that we'll need */
674 if (allocate_cg_links(root_count
, &tmp_cg_links
) < 0) {
679 atomic_set(&res
->refcount
, 1);
680 INIT_LIST_HEAD(&res
->cg_links
);
681 INIT_LIST_HEAD(&res
->tasks
);
682 INIT_HLIST_NODE(&res
->hlist
);
684 /* Copy the set of subsystem state objects generated in
685 * find_existing_css_set() */
686 memcpy(res
->subsys
, template, sizeof(res
->subsys
));
688 write_lock(&css_set_lock
);
689 /* Add reference counts and links from the new css_set. */
690 list_for_each_entry(link
, &oldcg
->cg_links
, cg_link_list
) {
691 struct cgroup
*c
= link
->cgrp
;
692 if (c
->root
== cgrp
->root
)
694 link_css_set(&tmp_cg_links
, res
, c
);
697 BUG_ON(!list_empty(&tmp_cg_links
));
701 /* Add this cgroup group to the hash table */
702 hhead
= css_set_hash(res
->subsys
);
703 hlist_add_head(&res
->hlist
, hhead
);
705 write_unlock(&css_set_lock
);
711 * Return the cgroup for "task" from the given hierarchy. Must be
712 * called with cgroup_mutex held.
714 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
715 struct cgroupfs_root
*root
)
718 struct cgroup
*res
= NULL
;
720 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
721 read_lock(&css_set_lock
);
723 * No need to lock the task - since we hold cgroup_mutex the
724 * task can't change groups, so the only thing that can happen
725 * is that it exits and its css is set back to init_css_set.
728 if (css
== &init_css_set
) {
729 res
= &root
->top_cgroup
;
731 struct cg_cgroup_link
*link
;
732 list_for_each_entry(link
, &css
->cg_links
, cg_link_list
) {
733 struct cgroup
*c
= link
->cgrp
;
734 if (c
->root
== root
) {
740 read_unlock(&css_set_lock
);
746 * There is one global cgroup mutex. We also require taking
747 * task_lock() when dereferencing a task's cgroup subsys pointers.
748 * See "The task_lock() exception", at the end of this comment.
750 * A task must hold cgroup_mutex to modify cgroups.
752 * Any task can increment and decrement the count field without lock.
753 * So in general, code holding cgroup_mutex can't rely on the count
754 * field not changing. However, if the count goes to zero, then only
755 * cgroup_attach_task() can increment it again. Because a count of zero
756 * means that no tasks are currently attached, therefore there is no
757 * way a task attached to that cgroup can fork (the other way to
758 * increment the count). So code holding cgroup_mutex can safely
759 * assume that if the count is zero, it will stay zero. Similarly, if
760 * a task holds cgroup_mutex on a cgroup with zero count, it
761 * knows that the cgroup won't be removed, as cgroup_rmdir()
764 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
765 * (usually) take cgroup_mutex. These are the two most performance
766 * critical pieces of code here. The exception occurs on cgroup_exit(),
767 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
768 * is taken, and if the cgroup count is zero, a usermode call made
769 * to the release agent with the name of the cgroup (path relative to
770 * the root of cgroup file system) as the argument.
772 * A cgroup can only be deleted if both its 'count' of using tasks
773 * is zero, and its list of 'children' cgroups is empty. Since all
774 * tasks in the system use _some_ cgroup, and since there is always at
775 * least one task in the system (init, pid == 1), therefore, top_cgroup
776 * always has either children cgroups and/or using tasks. So we don't
777 * need a special hack to ensure that top_cgroup cannot be deleted.
779 * The task_lock() exception
781 * The need for this exception arises from the action of
782 * cgroup_attach_task(), which overwrites one tasks cgroup pointer with
783 * another. It does so using cgroup_mutex, however there are
784 * several performance critical places that need to reference
785 * task->cgroup without the expense of grabbing a system global
786 * mutex. Therefore except as noted below, when dereferencing or, as
787 * in cgroup_attach_task(), modifying a task'ss cgroup pointer we use
788 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
789 * the task_struct routinely used for such matters.
791 * P.S. One more locking exception. RCU is used to guard the
792 * update of a tasks cgroup pointer by cgroup_attach_task()
796 * cgroup_lock - lock out any changes to cgroup structures
799 void cgroup_lock(void)
801 mutex_lock(&cgroup_mutex
);
803 EXPORT_SYMBOL_GPL(cgroup_lock
);
806 * cgroup_unlock - release lock on cgroup changes
808 * Undo the lock taken in a previous cgroup_lock() call.
810 void cgroup_unlock(void)
812 mutex_unlock(&cgroup_mutex
);
814 EXPORT_SYMBOL_GPL(cgroup_unlock
);
817 * A couple of forward declarations required, due to cyclic reference loop:
818 * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
819 * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
823 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
);
824 static struct dentry
*cgroup_lookup(struct inode
*, struct dentry
*, unsigned int);
825 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
);
826 static int cgroup_populate_dir(struct cgroup
*cgrp
, bool base_files
,
827 unsigned long subsys_mask
);
828 static const struct inode_operations cgroup_dir_inode_operations
;
829 static const struct file_operations proc_cgroupstats_operations
;
831 static struct backing_dev_info cgroup_backing_dev_info
= {
833 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
,
836 static int alloc_css_id(struct cgroup_subsys
*ss
,
837 struct cgroup
*parent
, struct cgroup
*child
);
839 static struct inode
*cgroup_new_inode(umode_t mode
, struct super_block
*sb
)
841 struct inode
*inode
= new_inode(sb
);
844 inode
->i_ino
= get_next_ino();
845 inode
->i_mode
= mode
;
846 inode
->i_uid
= current_fsuid();
847 inode
->i_gid
= current_fsgid();
848 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
849 inode
->i_mapping
->backing_dev_info
= &cgroup_backing_dev_info
;
854 static void cgroup_diput(struct dentry
*dentry
, struct inode
*inode
)
856 /* is dentry a directory ? if so, kfree() associated cgroup */
857 if (S_ISDIR(inode
->i_mode
)) {
858 struct cgroup
*cgrp
= dentry
->d_fsdata
;
859 struct cgroup_subsys
*ss
;
860 BUG_ON(!(cgroup_is_removed(cgrp
)));
861 /* It's possible for external users to be holding css
862 * reference counts on a cgroup; css_put() needs to
863 * be able to access the cgroup after decrementing
864 * the reference count in order to know if it needs to
865 * queue the cgroup to be handled by the release
869 mutex_lock(&cgroup_mutex
);
871 * Release the subsystem state objects.
873 for_each_subsys(cgrp
->root
, ss
)
876 cgrp
->root
->number_of_cgroups
--;
877 mutex_unlock(&cgroup_mutex
);
880 * Drop the active superblock reference that we took when we
883 deactivate_super(cgrp
->root
->sb
);
886 * if we're getting rid of the cgroup, refcount should ensure
887 * that there are no pidlists left.
889 BUG_ON(!list_empty(&cgrp
->pidlists
));
891 simple_xattrs_free(&cgrp
->xattrs
);
893 kfree_rcu(cgrp
, rcu_head
);
895 struct cfent
*cfe
= __d_cfe(dentry
);
896 struct cgroup
*cgrp
= dentry
->d_parent
->d_fsdata
;
897 struct cftype
*cft
= cfe
->type
;
899 WARN_ONCE(!list_empty(&cfe
->node
) &&
900 cgrp
!= &cgrp
->root
->top_cgroup
,
901 "cfe still linked for %s\n", cfe
->type
->name
);
903 simple_xattrs_free(&cft
->xattrs
);
908 static int cgroup_delete(const struct dentry
*d
)
913 static void remove_dir(struct dentry
*d
)
915 struct dentry
*parent
= dget(d
->d_parent
);
918 simple_rmdir(parent
->d_inode
, d
);
922 static int cgroup_rm_file(struct cgroup
*cgrp
, const struct cftype
*cft
)
926 lockdep_assert_held(&cgrp
->dentry
->d_inode
->i_mutex
);
927 lockdep_assert_held(&cgroup_mutex
);
929 list_for_each_entry(cfe
, &cgrp
->files
, node
) {
930 struct dentry
*d
= cfe
->dentry
;
932 if (cft
&& cfe
->type
!= cft
)
937 simple_unlink(cgrp
->dentry
->d_inode
, d
);
938 list_del_init(&cfe
->node
);
947 * cgroup_clear_directory - selective removal of base and subsystem files
948 * @dir: directory containing the files
949 * @base_files: true if the base files should be removed
950 * @subsys_mask: mask of the subsystem ids whose files should be removed
952 static void cgroup_clear_directory(struct dentry
*dir
, bool base_files
,
953 unsigned long subsys_mask
)
955 struct cgroup
*cgrp
= __d_cgrp(dir
);
956 struct cgroup_subsys
*ss
;
958 for_each_subsys(cgrp
->root
, ss
) {
959 struct cftype_set
*set
;
960 if (!test_bit(ss
->subsys_id
, &subsys_mask
))
962 list_for_each_entry(set
, &ss
->cftsets
, node
)
963 cgroup_rm_file(cgrp
, set
->cfts
);
966 while (!list_empty(&cgrp
->files
))
967 cgroup_rm_file(cgrp
, NULL
);
972 * NOTE : the dentry must have been dget()'ed
974 static void cgroup_d_remove_dir(struct dentry
*dentry
)
976 struct dentry
*parent
;
977 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
979 cgroup_clear_directory(dentry
, true, root
->subsys_mask
);
981 parent
= dentry
->d_parent
;
982 spin_lock(&parent
->d_lock
);
983 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
984 list_del_init(&dentry
->d_u
.d_child
);
985 spin_unlock(&dentry
->d_lock
);
986 spin_unlock(&parent
->d_lock
);
991 * Call with cgroup_mutex held. Drops reference counts on modules, including
992 * any duplicate ones that parse_cgroupfs_options took. If this function
993 * returns an error, no reference counts are touched.
995 static int rebind_subsystems(struct cgroupfs_root
*root
,
996 unsigned long final_subsys_mask
)
998 unsigned long added_mask
, removed_mask
;
999 struct cgroup
*cgrp
= &root
->top_cgroup
;
1002 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
1003 BUG_ON(!mutex_is_locked(&cgroup_root_mutex
));
1005 removed_mask
= root
->actual_subsys_mask
& ~final_subsys_mask
;
1006 added_mask
= final_subsys_mask
& ~root
->actual_subsys_mask
;
1007 /* Check that any added subsystems are currently free */
1008 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1009 unsigned long bit
= 1UL << i
;
1010 struct cgroup_subsys
*ss
= subsys
[i
];
1011 if (!(bit
& added_mask
))
1014 * Nobody should tell us to do a subsys that doesn't exist:
1015 * parse_cgroupfs_options should catch that case and refcounts
1016 * ensure that subsystems won't disappear once selected.
1019 if (ss
->root
!= &rootnode
) {
1020 /* Subsystem isn't free */
1025 /* Currently we don't handle adding/removing subsystems when
1026 * any child cgroups exist. This is theoretically supportable
1027 * but involves complex error handling, so it's being left until
1029 if (root
->number_of_cgroups
> 1)
1032 /* Process each subsystem */
1033 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1034 struct cgroup_subsys
*ss
= subsys
[i
];
1035 unsigned long bit
= 1UL << i
;
1036 if (bit
& added_mask
) {
1037 /* We're binding this subsystem to this hierarchy */
1039 BUG_ON(cgrp
->subsys
[i
]);
1040 BUG_ON(!dummytop
->subsys
[i
]);
1041 BUG_ON(dummytop
->subsys
[i
]->cgroup
!= dummytop
);
1042 cgrp
->subsys
[i
] = dummytop
->subsys
[i
];
1043 cgrp
->subsys
[i
]->cgroup
= cgrp
;
1044 list_move(&ss
->sibling
, &root
->subsys_list
);
1048 /* refcount was already taken, and we're keeping it */
1049 } else if (bit
& removed_mask
) {
1050 /* We're removing this subsystem */
1052 BUG_ON(cgrp
->subsys
[i
] != dummytop
->subsys
[i
]);
1053 BUG_ON(cgrp
->subsys
[i
]->cgroup
!= cgrp
);
1056 dummytop
->subsys
[i
]->cgroup
= dummytop
;
1057 cgrp
->subsys
[i
] = NULL
;
1058 subsys
[i
]->root
= &rootnode
;
1059 list_move(&ss
->sibling
, &rootnode
.subsys_list
);
1060 /* subsystem is now free - drop reference on module */
1061 module_put(ss
->module
);
1062 } else if (bit
& final_subsys_mask
) {
1063 /* Subsystem state should already exist */
1065 BUG_ON(!cgrp
->subsys
[i
]);
1067 * a refcount was taken, but we already had one, so
1068 * drop the extra reference.
1070 module_put(ss
->module
);
1071 #ifdef CONFIG_MODULE_UNLOAD
1072 BUG_ON(ss
->module
&& !module_refcount(ss
->module
));
1075 /* Subsystem state shouldn't exist */
1076 BUG_ON(cgrp
->subsys
[i
]);
1079 root
->subsys_mask
= root
->actual_subsys_mask
= final_subsys_mask
;
1085 static int cgroup_show_options(struct seq_file
*seq
, struct dentry
*dentry
)
1087 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
1088 struct cgroup_subsys
*ss
;
1090 mutex_lock(&cgroup_root_mutex
);
1091 for_each_subsys(root
, ss
)
1092 seq_printf(seq
, ",%s", ss
->name
);
1093 if (test_bit(ROOT_NOPREFIX
, &root
->flags
))
1094 seq_puts(seq
, ",noprefix");
1095 if (test_bit(ROOT_XATTR
, &root
->flags
))
1096 seq_puts(seq
, ",xattr");
1097 if (strlen(root
->release_agent_path
))
1098 seq_printf(seq
, ",release_agent=%s", root
->release_agent_path
);
1099 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
))
1100 seq_puts(seq
, ",clone_children");
1101 if (strlen(root
->name
))
1102 seq_printf(seq
, ",name=%s", root
->name
);
1103 mutex_unlock(&cgroup_root_mutex
);
1107 struct cgroup_sb_opts
{
1108 unsigned long subsys_mask
;
1109 unsigned long flags
;
1110 char *release_agent
;
1111 bool cpuset_clone_children
;
1113 /* User explicitly requested empty subsystem */
1116 struct cgroupfs_root
*new_root
;
1121 * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call
1122 * with cgroup_mutex held to protect the subsys[] array. This function takes
1123 * refcounts on subsystems to be used, unless it returns error, in which case
1124 * no refcounts are taken.
1126 static int parse_cgroupfs_options(char *data
, struct cgroup_sb_opts
*opts
)
1128 char *token
, *o
= data
;
1129 bool all_ss
= false, one_ss
= false;
1130 unsigned long mask
= (unsigned long)-1;
1132 bool module_pin_failed
= false;
1134 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
1136 #ifdef CONFIG_CPUSETS
1137 mask
= ~(1UL << cpuset_subsys_id
);
1140 memset(opts
, 0, sizeof(*opts
));
1142 while ((token
= strsep(&o
, ",")) != NULL
) {
1145 if (!strcmp(token
, "none")) {
1146 /* Explicitly have no subsystems */
1150 if (!strcmp(token
, "all")) {
1151 /* Mutually exclusive option 'all' + subsystem name */
1157 if (!strcmp(token
, "noprefix")) {
1158 set_bit(ROOT_NOPREFIX
, &opts
->flags
);
1161 if (!strcmp(token
, "clone_children")) {
1162 opts
->cpuset_clone_children
= true;
1165 if (!strcmp(token
, "xattr")) {
1166 set_bit(ROOT_XATTR
, &opts
->flags
);
1169 if (!strncmp(token
, "release_agent=", 14)) {
1170 /* Specifying two release agents is forbidden */
1171 if (opts
->release_agent
)
1173 opts
->release_agent
=
1174 kstrndup(token
+ 14, PATH_MAX
- 1, GFP_KERNEL
);
1175 if (!opts
->release_agent
)
1179 if (!strncmp(token
, "name=", 5)) {
1180 const char *name
= token
+ 5;
1181 /* Can't specify an empty name */
1184 /* Must match [\w.-]+ */
1185 for (i
= 0; i
< strlen(name
); i
++) {
1189 if ((c
== '.') || (c
== '-') || (c
== '_'))
1193 /* Specifying two names is forbidden */
1196 opts
->name
= kstrndup(name
,
1197 MAX_CGROUP_ROOT_NAMELEN
- 1,
1205 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1206 struct cgroup_subsys
*ss
= subsys
[i
];
1209 if (strcmp(token
, ss
->name
))
1214 /* Mutually exclusive option 'all' + subsystem name */
1217 set_bit(i
, &opts
->subsys_mask
);
1222 if (i
== CGROUP_SUBSYS_COUNT
)
1227 * If the 'all' option was specified select all the subsystems,
1228 * otherwise if 'none', 'name=' and a subsystem name options
1229 * were not specified, let's default to 'all'
1231 if (all_ss
|| (!one_ss
&& !opts
->none
&& !opts
->name
)) {
1232 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1233 struct cgroup_subsys
*ss
= subsys
[i
];
1238 set_bit(i
, &opts
->subsys_mask
);
1242 /* Consistency checks */
1245 * Option noprefix was introduced just for backward compatibility
1246 * with the old cpuset, so we allow noprefix only if mounting just
1247 * the cpuset subsystem.
1249 if (test_bit(ROOT_NOPREFIX
, &opts
->flags
) &&
1250 (opts
->subsys_mask
& mask
))
1254 /* Can't specify "none" and some subsystems */
1255 if (opts
->subsys_mask
&& opts
->none
)
1259 * We either have to specify by name or by subsystems. (So all
1260 * empty hierarchies must have a name).
1262 if (!opts
->subsys_mask
&& !opts
->name
)
1266 * Grab references on all the modules we'll need, so the subsystems
1267 * don't dance around before rebind_subsystems attaches them. This may
1268 * take duplicate reference counts on a subsystem that's already used,
1269 * but rebind_subsystems handles this case.
1271 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1272 unsigned long bit
= 1UL << i
;
1274 if (!(bit
& opts
->subsys_mask
))
1276 if (!try_module_get(subsys
[i
]->module
)) {
1277 module_pin_failed
= true;
1281 if (module_pin_failed
) {
1283 * oops, one of the modules was going away. this means that we
1284 * raced with a module_delete call, and to the user this is
1285 * essentially a "subsystem doesn't exist" case.
1287 for (i
--; i
>= 0; i
--) {
1288 /* drop refcounts only on the ones we took */
1289 unsigned long bit
= 1UL << i
;
1291 if (!(bit
& opts
->subsys_mask
))
1293 module_put(subsys
[i
]->module
);
1301 static void drop_parsed_module_refcounts(unsigned long subsys_mask
)
1304 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1305 unsigned long bit
= 1UL << i
;
1307 if (!(bit
& subsys_mask
))
1309 module_put(subsys
[i
]->module
);
1313 static int cgroup_remount(struct super_block
*sb
, int *flags
, char *data
)
1316 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1317 struct cgroup
*cgrp
= &root
->top_cgroup
;
1318 struct cgroup_sb_opts opts
;
1319 unsigned long added_mask
, removed_mask
;
1321 mutex_lock(&cgrp
->dentry
->d_inode
->i_mutex
);
1322 mutex_lock(&cgroup_mutex
);
1323 mutex_lock(&cgroup_root_mutex
);
1325 /* See what subsystems are wanted */
1326 ret
= parse_cgroupfs_options(data
, &opts
);
1330 /* See feature-removal-schedule.txt */
1331 if (opts
.subsys_mask
!= root
->actual_subsys_mask
|| opts
.release_agent
)
1332 pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
1333 task_tgid_nr(current
), current
->comm
);
1335 added_mask
= opts
.subsys_mask
& ~root
->subsys_mask
;
1336 removed_mask
= root
->subsys_mask
& ~opts
.subsys_mask
;
1338 /* Don't allow flags or name to change at remount */
1339 if (opts
.flags
!= root
->flags
||
1340 (opts
.name
&& strcmp(opts
.name
, root
->name
))) {
1342 drop_parsed_module_refcounts(opts
.subsys_mask
);
1346 ret
= rebind_subsystems(root
, opts
.subsys_mask
);
1348 drop_parsed_module_refcounts(opts
.subsys_mask
);
1352 /* clear out any existing files and repopulate subsystem files */
1353 cgroup_clear_directory(cgrp
->dentry
, false, removed_mask
);
1354 /* re-populate subsystem files */
1355 cgroup_populate_dir(cgrp
, false, added_mask
);
1357 if (opts
.release_agent
)
1358 strcpy(root
->release_agent_path
, opts
.release_agent
);
1360 kfree(opts
.release_agent
);
1362 mutex_unlock(&cgroup_root_mutex
);
1363 mutex_unlock(&cgroup_mutex
);
1364 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
1368 static const struct super_operations cgroup_ops
= {
1369 .statfs
= simple_statfs
,
1370 .drop_inode
= generic_delete_inode
,
1371 .show_options
= cgroup_show_options
,
1372 .remount_fs
= cgroup_remount
,
1375 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1377 INIT_LIST_HEAD(&cgrp
->sibling
);
1378 INIT_LIST_HEAD(&cgrp
->children
);
1379 INIT_LIST_HEAD(&cgrp
->files
);
1380 INIT_LIST_HEAD(&cgrp
->css_sets
);
1381 INIT_LIST_HEAD(&cgrp
->allcg_node
);
1382 INIT_LIST_HEAD(&cgrp
->release_list
);
1383 INIT_LIST_HEAD(&cgrp
->pidlists
);
1384 mutex_init(&cgrp
->pidlist_mutex
);
1385 INIT_LIST_HEAD(&cgrp
->event_list
);
1386 spin_lock_init(&cgrp
->event_list_lock
);
1387 simple_xattrs_init(&cgrp
->xattrs
);
1390 static void init_cgroup_root(struct cgroupfs_root
*root
)
1392 struct cgroup
*cgrp
= &root
->top_cgroup
;
1394 INIT_LIST_HEAD(&root
->subsys_list
);
1395 INIT_LIST_HEAD(&root
->root_list
);
1396 INIT_LIST_HEAD(&root
->allcg_list
);
1397 root
->number_of_cgroups
= 1;
1399 cgrp
->top_cgroup
= cgrp
;
1400 list_add_tail(&cgrp
->allcg_node
, &root
->allcg_list
);
1401 init_cgroup_housekeeping(cgrp
);
1404 static bool init_root_id(struct cgroupfs_root
*root
)
1409 if (!ida_pre_get(&hierarchy_ida
, GFP_KERNEL
))
1411 spin_lock(&hierarchy_id_lock
);
1412 /* Try to allocate the next unused ID */
1413 ret
= ida_get_new_above(&hierarchy_ida
, next_hierarchy_id
,
1414 &root
->hierarchy_id
);
1416 /* Try again starting from 0 */
1417 ret
= ida_get_new(&hierarchy_ida
, &root
->hierarchy_id
);
1419 next_hierarchy_id
= root
->hierarchy_id
+ 1;
1420 } else if (ret
!= -EAGAIN
) {
1421 /* Can only get here if the 31-bit IDR is full ... */
1424 spin_unlock(&hierarchy_id_lock
);
1429 static int cgroup_test_super(struct super_block
*sb
, void *data
)
1431 struct cgroup_sb_opts
*opts
= data
;
1432 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1434 /* If we asked for a name then it must match */
1435 if (opts
->name
&& strcmp(opts
->name
, root
->name
))
1439 * If we asked for subsystems (or explicitly for no
1440 * subsystems) then they must match
1442 if ((opts
->subsys_mask
|| opts
->none
)
1443 && (opts
->subsys_mask
!= root
->subsys_mask
))
1449 static struct cgroupfs_root
*cgroup_root_from_opts(struct cgroup_sb_opts
*opts
)
1451 struct cgroupfs_root
*root
;
1453 if (!opts
->subsys_mask
&& !opts
->none
)
1456 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
1458 return ERR_PTR(-ENOMEM
);
1460 if (!init_root_id(root
)) {
1462 return ERR_PTR(-ENOMEM
);
1464 init_cgroup_root(root
);
1466 root
->subsys_mask
= opts
->subsys_mask
;
1467 root
->flags
= opts
->flags
;
1468 if (opts
->release_agent
)
1469 strcpy(root
->release_agent_path
, opts
->release_agent
);
1471 strcpy(root
->name
, opts
->name
);
1472 if (opts
->cpuset_clone_children
)
1473 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
);
1477 static void cgroup_drop_root(struct cgroupfs_root
*root
)
1482 BUG_ON(!root
->hierarchy_id
);
1483 spin_lock(&hierarchy_id_lock
);
1484 ida_remove(&hierarchy_ida
, root
->hierarchy_id
);
1485 spin_unlock(&hierarchy_id_lock
);
1489 static int cgroup_set_super(struct super_block
*sb
, void *data
)
1492 struct cgroup_sb_opts
*opts
= data
;
1494 /* If we don't have a new root, we can't set up a new sb */
1495 if (!opts
->new_root
)
1498 BUG_ON(!opts
->subsys_mask
&& !opts
->none
);
1500 ret
= set_anon_super(sb
, NULL
);
1504 sb
->s_fs_info
= opts
->new_root
;
1505 opts
->new_root
->sb
= sb
;
1507 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
1508 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
1509 sb
->s_magic
= CGROUP_SUPER_MAGIC
;
1510 sb
->s_op
= &cgroup_ops
;
1515 static int cgroup_get_rootdir(struct super_block
*sb
)
1517 static const struct dentry_operations cgroup_dops
= {
1518 .d_iput
= cgroup_diput
,
1519 .d_delete
= cgroup_delete
,
1522 struct inode
*inode
=
1523 cgroup_new_inode(S_IFDIR
| S_IRUGO
| S_IXUGO
| S_IWUSR
, sb
);
1528 inode
->i_fop
= &simple_dir_operations
;
1529 inode
->i_op
= &cgroup_dir_inode_operations
;
1530 /* directories start off with i_nlink == 2 (for "." entry) */
1532 sb
->s_root
= d_make_root(inode
);
1535 /* for everything else we want ->d_op set */
1536 sb
->s_d_op
= &cgroup_dops
;
1540 static struct dentry
*cgroup_mount(struct file_system_type
*fs_type
,
1541 int flags
, const char *unused_dev_name
,
1544 struct cgroup_sb_opts opts
;
1545 struct cgroupfs_root
*root
;
1547 struct super_block
*sb
;
1548 struct cgroupfs_root
*new_root
;
1549 struct inode
*inode
;
1551 /* First find the desired set of subsystems */
1552 mutex_lock(&cgroup_mutex
);
1553 ret
= parse_cgroupfs_options(data
, &opts
);
1554 mutex_unlock(&cgroup_mutex
);
1559 * Allocate a new cgroup root. We may not need it if we're
1560 * reusing an existing hierarchy.
1562 new_root
= cgroup_root_from_opts(&opts
);
1563 if (IS_ERR(new_root
)) {
1564 ret
= PTR_ERR(new_root
);
1567 opts
.new_root
= new_root
;
1569 /* Locate an existing or new sb for this hierarchy */
1570 sb
= sget(fs_type
, cgroup_test_super
, cgroup_set_super
, 0, &opts
);
1573 cgroup_drop_root(opts
.new_root
);
1577 root
= sb
->s_fs_info
;
1579 if (root
== opts
.new_root
) {
1580 /* We used the new root structure, so this is a new hierarchy */
1581 struct list_head tmp_cg_links
;
1582 struct cgroup
*root_cgrp
= &root
->top_cgroup
;
1583 struct cgroupfs_root
*existing_root
;
1584 const struct cred
*cred
;
1587 BUG_ON(sb
->s_root
!= NULL
);
1589 ret
= cgroup_get_rootdir(sb
);
1591 goto drop_new_super
;
1592 inode
= sb
->s_root
->d_inode
;
1594 mutex_lock(&inode
->i_mutex
);
1595 mutex_lock(&cgroup_mutex
);
1596 mutex_lock(&cgroup_root_mutex
);
1598 /* Check for name clashes with existing mounts */
1600 if (strlen(root
->name
))
1601 for_each_active_root(existing_root
)
1602 if (!strcmp(existing_root
->name
, root
->name
))
1606 * We're accessing css_set_count without locking
1607 * css_set_lock here, but that's OK - it can only be
1608 * increased by someone holding cgroup_lock, and
1609 * that's us. The worst that can happen is that we
1610 * have some link structures left over
1612 ret
= allocate_cg_links(css_set_count
, &tmp_cg_links
);
1616 ret
= rebind_subsystems(root
, root
->subsys_mask
);
1617 if (ret
== -EBUSY
) {
1618 free_cg_links(&tmp_cg_links
);
1622 * There must be no failure case after here, since rebinding
1623 * takes care of subsystems' refcounts, which are explicitly
1624 * dropped in the failure exit path.
1627 /* EBUSY should be the only error here */
1630 list_add(&root
->root_list
, &roots
);
1633 sb
->s_root
->d_fsdata
= root_cgrp
;
1634 root
->top_cgroup
.dentry
= sb
->s_root
;
1636 /* Link the top cgroup in this hierarchy into all
1637 * the css_set objects */
1638 write_lock(&css_set_lock
);
1639 for (i
= 0; i
< CSS_SET_TABLE_SIZE
; i
++) {
1640 struct hlist_head
*hhead
= &css_set_table
[i
];
1641 struct hlist_node
*node
;
1644 hlist_for_each_entry(cg
, node
, hhead
, hlist
)
1645 link_css_set(&tmp_cg_links
, cg
, root_cgrp
);
1647 write_unlock(&css_set_lock
);
1649 free_cg_links(&tmp_cg_links
);
1651 BUG_ON(!list_empty(&root_cgrp
->children
));
1652 BUG_ON(root
->number_of_cgroups
!= 1);
1654 cred
= override_creds(&init_cred
);
1655 cgroup_populate_dir(root_cgrp
, true, root
->subsys_mask
);
1657 mutex_unlock(&cgroup_root_mutex
);
1658 mutex_unlock(&cgroup_mutex
);
1659 mutex_unlock(&inode
->i_mutex
);
1662 * We re-used an existing hierarchy - the new root (if
1663 * any) is not needed
1665 cgroup_drop_root(opts
.new_root
);
1666 /* no subsys rebinding, so refcounts don't change */
1667 drop_parsed_module_refcounts(opts
.subsys_mask
);
1670 kfree(opts
.release_agent
);
1672 return dget(sb
->s_root
);
1675 mutex_unlock(&cgroup_root_mutex
);
1676 mutex_unlock(&cgroup_mutex
);
1677 mutex_unlock(&inode
->i_mutex
);
1679 deactivate_locked_super(sb
);
1681 drop_parsed_module_refcounts(opts
.subsys_mask
);
1683 kfree(opts
.release_agent
);
1685 return ERR_PTR(ret
);
1688 static void cgroup_kill_sb(struct super_block
*sb
) {
1689 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1690 struct cgroup
*cgrp
= &root
->top_cgroup
;
1692 struct cg_cgroup_link
*link
;
1693 struct cg_cgroup_link
*saved_link
;
1697 BUG_ON(root
->number_of_cgroups
!= 1);
1698 BUG_ON(!list_empty(&cgrp
->children
));
1700 mutex_lock(&cgroup_mutex
);
1701 mutex_lock(&cgroup_root_mutex
);
1703 /* Rebind all subsystems back to the default hierarchy */
1704 ret
= rebind_subsystems(root
, 0);
1705 /* Shouldn't be able to fail ... */
1709 * Release all the links from css_sets to this hierarchy's
1712 write_lock(&css_set_lock
);
1714 list_for_each_entry_safe(link
, saved_link
, &cgrp
->css_sets
,
1716 list_del(&link
->cg_link_list
);
1717 list_del(&link
->cgrp_link_list
);
1720 write_unlock(&css_set_lock
);
1722 if (!list_empty(&root
->root_list
)) {
1723 list_del(&root
->root_list
);
1727 mutex_unlock(&cgroup_root_mutex
);
1728 mutex_unlock(&cgroup_mutex
);
1730 simple_xattrs_free(&cgrp
->xattrs
);
1732 kill_litter_super(sb
);
1733 cgroup_drop_root(root
);
1736 static struct file_system_type cgroup_fs_type
= {
1738 .mount
= cgroup_mount
,
1739 .kill_sb
= cgroup_kill_sb
,
1742 static struct kobject
*cgroup_kobj
;
1745 * cgroup_path - generate the path of a cgroup
1746 * @cgrp: the cgroup in question
1747 * @buf: the buffer to write the path into
1748 * @buflen: the length of the buffer
1750 * Called with cgroup_mutex held or else with an RCU-protected cgroup
1751 * reference. Writes path of cgroup into buf. Returns 0 on success,
1754 int cgroup_path(const struct cgroup
*cgrp
, char *buf
, int buflen
)
1756 struct dentry
*dentry
= cgrp
->dentry
;
1759 rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(),
1760 "cgroup_path() called without proper locking");
1762 if (!dentry
|| cgrp
== dummytop
) {
1764 * Inactive subsystems have no dentry for their root
1771 start
= buf
+ buflen
- 1;
1775 int len
= dentry
->d_name
.len
;
1777 if ((start
-= len
) < buf
)
1778 return -ENAMETOOLONG
;
1779 memcpy(start
, dentry
->d_name
.name
, len
);
1780 cgrp
= cgrp
->parent
;
1784 dentry
= cgrp
->dentry
;
1788 return -ENAMETOOLONG
;
1791 memmove(buf
, start
, buf
+ buflen
- start
);
1794 EXPORT_SYMBOL_GPL(cgroup_path
);
1797 * Control Group taskset
1799 struct task_and_cgroup
{
1800 struct task_struct
*task
;
1801 struct cgroup
*cgrp
;
1805 struct cgroup_taskset
{
1806 struct task_and_cgroup single
;
1807 struct flex_array
*tc_array
;
1810 struct cgroup
*cur_cgrp
;
1814 * cgroup_taskset_first - reset taskset and return the first task
1815 * @tset: taskset of interest
1817 * @tset iteration is initialized and the first task is returned.
1819 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
)
1821 if (tset
->tc_array
) {
1823 return cgroup_taskset_next(tset
);
1825 tset
->cur_cgrp
= tset
->single
.cgrp
;
1826 return tset
->single
.task
;
1829 EXPORT_SYMBOL_GPL(cgroup_taskset_first
);
1832 * cgroup_taskset_next - iterate to the next task in taskset
1833 * @tset: taskset of interest
1835 * Return the next task in @tset. Iteration must have been initialized
1836 * with cgroup_taskset_first().
1838 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
)
1840 struct task_and_cgroup
*tc
;
1842 if (!tset
->tc_array
|| tset
->idx
>= tset
->tc_array_len
)
1845 tc
= flex_array_get(tset
->tc_array
, tset
->idx
++);
1846 tset
->cur_cgrp
= tc
->cgrp
;
1849 EXPORT_SYMBOL_GPL(cgroup_taskset_next
);
1852 * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task
1853 * @tset: taskset of interest
1855 * Return the cgroup for the current (last returned) task of @tset. This
1856 * function must be preceded by either cgroup_taskset_first() or
1857 * cgroup_taskset_next().
1859 struct cgroup
*cgroup_taskset_cur_cgroup(struct cgroup_taskset
*tset
)
1861 return tset
->cur_cgrp
;
1863 EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup
);
1866 * cgroup_taskset_size - return the number of tasks in taskset
1867 * @tset: taskset of interest
1869 int cgroup_taskset_size(struct cgroup_taskset
*tset
)
1871 return tset
->tc_array
? tset
->tc_array_len
: 1;
1873 EXPORT_SYMBOL_GPL(cgroup_taskset_size
);
1877 * cgroup_task_migrate - move a task from one cgroup to another.
1879 * 'guarantee' is set if the caller promises that a new css_set for the task
1880 * will already exist. If not set, this function might sleep, and can fail with
1881 * -ENOMEM. Must be called with cgroup_mutex and threadgroup locked.
1883 static void cgroup_task_migrate(struct cgroup
*cgrp
, struct cgroup
*oldcgrp
,
1884 struct task_struct
*tsk
, struct css_set
*newcg
)
1886 struct css_set
*oldcg
;
1889 * We are synchronized through threadgroup_lock() against PF_EXITING
1890 * setting such that we can't race against cgroup_exit() changing the
1891 * css_set to init_css_set and dropping the old one.
1893 WARN_ON_ONCE(tsk
->flags
& PF_EXITING
);
1894 oldcg
= tsk
->cgroups
;
1897 rcu_assign_pointer(tsk
->cgroups
, newcg
);
1900 /* Update the css_set linked lists if we're using them */
1901 write_lock(&css_set_lock
);
1902 if (!list_empty(&tsk
->cg_list
))
1903 list_move(&tsk
->cg_list
, &newcg
->tasks
);
1904 write_unlock(&css_set_lock
);
1907 * We just gained a reference on oldcg by taking it from the task. As
1908 * trading it for newcg is protected by cgroup_mutex, we're safe to drop
1909 * it here; it will be freed under RCU.
1911 set_bit(CGRP_RELEASABLE
, &oldcgrp
->flags
);
1916 * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
1917 * @cgrp: the cgroup the task is attaching to
1918 * @tsk: the task to be attached
1920 * Call with cgroup_mutex and threadgroup locked. May take task_lock of
1923 int cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
)
1926 struct cgroup_subsys
*ss
, *failed_ss
= NULL
;
1927 struct cgroup
*oldcgrp
;
1928 struct cgroupfs_root
*root
= cgrp
->root
;
1929 struct cgroup_taskset tset
= { };
1930 struct css_set
*newcg
;
1932 /* @tsk either already exited or can't exit until the end */
1933 if (tsk
->flags
& PF_EXITING
)
1936 /* Nothing to do if the task is already in that cgroup */
1937 oldcgrp
= task_cgroup_from_root(tsk
, root
);
1938 if (cgrp
== oldcgrp
)
1941 tset
.single
.task
= tsk
;
1942 tset
.single
.cgrp
= oldcgrp
;
1944 for_each_subsys(root
, ss
) {
1945 if (ss
->can_attach
) {
1946 retval
= ss
->can_attach(cgrp
, &tset
);
1949 * Remember on which subsystem the can_attach()
1950 * failed, so that we only call cancel_attach()
1951 * against the subsystems whose can_attach()
1952 * succeeded. (See below)
1960 newcg
= find_css_set(tsk
->cgroups
, cgrp
);
1966 cgroup_task_migrate(cgrp
, oldcgrp
, tsk
, newcg
);
1968 for_each_subsys(root
, ss
) {
1970 ss
->attach(cgrp
, &tset
);
1976 for_each_subsys(root
, ss
) {
1977 if (ss
== failed_ss
)
1979 * This subsystem was the one that failed the
1980 * can_attach() check earlier, so we don't need
1981 * to call cancel_attach() against it or any
1982 * remaining subsystems.
1985 if (ss
->cancel_attach
)
1986 ss
->cancel_attach(cgrp
, &tset
);
1993 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
1994 * @from: attach to all cgroups of a given task
1995 * @tsk: the task to be attached
1997 int cgroup_attach_task_all(struct task_struct
*from
, struct task_struct
*tsk
)
1999 struct cgroupfs_root
*root
;
2003 for_each_active_root(root
) {
2004 struct cgroup
*from_cg
= task_cgroup_from_root(from
, root
);
2006 retval
= cgroup_attach_task(from_cg
, tsk
);
2014 EXPORT_SYMBOL_GPL(cgroup_attach_task_all
);
2017 * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup
2018 * @cgrp: the cgroup to attach to
2019 * @leader: the threadgroup leader task_struct of the group to be attached
2021 * Call holding cgroup_mutex and the group_rwsem of the leader. Will take
2022 * task_lock of each thread in leader's threadgroup individually in turn.
2024 static int cgroup_attach_proc(struct cgroup
*cgrp
, struct task_struct
*leader
)
2026 int retval
, i
, group_size
;
2027 struct cgroup_subsys
*ss
, *failed_ss
= NULL
;
2028 /* guaranteed to be initialized later, but the compiler needs this */
2029 struct cgroupfs_root
*root
= cgrp
->root
;
2030 /* threadgroup list cursor and array */
2031 struct task_struct
*tsk
;
2032 struct task_and_cgroup
*tc
;
2033 struct flex_array
*group
;
2034 struct cgroup_taskset tset
= { };
2037 * step 0: in order to do expensive, possibly blocking operations for
2038 * every thread, we cannot iterate the thread group list, since it needs
2039 * rcu or tasklist locked. instead, build an array of all threads in the
2040 * group - group_rwsem prevents new threads from appearing, and if
2041 * threads exit, this will just be an over-estimate.
2043 group_size
= get_nr_threads(leader
);
2044 /* flex_array supports very large thread-groups better than kmalloc. */
2045 group
= flex_array_alloc(sizeof(*tc
), group_size
, GFP_KERNEL
);
2048 /* pre-allocate to guarantee space while iterating in rcu read-side. */
2049 retval
= flex_array_prealloc(group
, 0, group_size
- 1, GFP_KERNEL
);
2051 goto out_free_group_list
;
2056 * Prevent freeing of tasks while we take a snapshot. Tasks that are
2057 * already PF_EXITING could be freed from underneath us unless we
2058 * take an rcu_read_lock.
2062 struct task_and_cgroup ent
;
2064 /* @tsk either already exited or can't exit until the end */
2065 if (tsk
->flags
& PF_EXITING
)
2068 /* as per above, nr_threads may decrease, but not increase. */
2069 BUG_ON(i
>= group_size
);
2071 ent
.cgrp
= task_cgroup_from_root(tsk
, root
);
2072 /* nothing to do if this task is already in the cgroup */
2073 if (ent
.cgrp
== cgrp
)
2076 * saying GFP_ATOMIC has no effect here because we did prealloc
2077 * earlier, but it's good form to communicate our expectations.
2079 retval
= flex_array_put(group
, i
, &ent
, GFP_ATOMIC
);
2080 BUG_ON(retval
!= 0);
2082 } while_each_thread(leader
, tsk
);
2084 /* remember the number of threads in the array for later. */
2086 tset
.tc_array
= group
;
2087 tset
.tc_array_len
= group_size
;
2089 /* methods shouldn't be called if no task is actually migrating */
2092 goto out_free_group_list
;
2095 * step 1: check that we can legitimately attach to the cgroup.
2097 for_each_subsys(root
, ss
) {
2098 if (ss
->can_attach
) {
2099 retval
= ss
->can_attach(cgrp
, &tset
);
2102 goto out_cancel_attach
;
2108 * step 2: make sure css_sets exist for all threads to be migrated.
2109 * we use find_css_set, which allocates a new one if necessary.
2111 for (i
= 0; i
< group_size
; i
++) {
2112 tc
= flex_array_get(group
, i
);
2113 tc
->cg
= find_css_set(tc
->task
->cgroups
, cgrp
);
2116 goto out_put_css_set_refs
;
2121 * step 3: now that we're guaranteed success wrt the css_sets,
2122 * proceed to move all tasks to the new cgroup. There are no
2123 * failure cases after here, so this is the commit point.
2125 for (i
= 0; i
< group_size
; i
++) {
2126 tc
= flex_array_get(group
, i
);
2127 cgroup_task_migrate(cgrp
, tc
->cgrp
, tc
->task
, tc
->cg
);
2129 /* nothing is sensitive to fork() after this point. */
2132 * step 4: do subsystem attach callbacks.
2134 for_each_subsys(root
, ss
) {
2136 ss
->attach(cgrp
, &tset
);
2140 * step 5: success! and cleanup
2144 out_put_css_set_refs
:
2146 for (i
= 0; i
< group_size
; i
++) {
2147 tc
= flex_array_get(group
, i
);
2150 put_css_set(tc
->cg
);
2155 for_each_subsys(root
, ss
) {
2156 if (ss
== failed_ss
)
2158 if (ss
->cancel_attach
)
2159 ss
->cancel_attach(cgrp
, &tset
);
2162 out_free_group_list
:
2163 flex_array_free(group
);
2168 * Find the task_struct of the task to attach by vpid and pass it along to the
2169 * function to attach either it or all tasks in its threadgroup. Will lock
2170 * cgroup_mutex and threadgroup; may take task_lock of task.
2172 static int attach_task_by_pid(struct cgroup
*cgrp
, u64 pid
, bool threadgroup
)
2174 struct task_struct
*tsk
;
2175 const struct cred
*cred
= current_cred(), *tcred
;
2178 if (!cgroup_lock_live_group(cgrp
))
2184 tsk
= find_task_by_vpid(pid
);
2188 goto out_unlock_cgroup
;
2191 * even if we're attaching all tasks in the thread group, we
2192 * only need to check permissions on one of them.
2194 tcred
= __task_cred(tsk
);
2195 if (!uid_eq(cred
->euid
, GLOBAL_ROOT_UID
) &&
2196 !uid_eq(cred
->euid
, tcred
->uid
) &&
2197 !uid_eq(cred
->euid
, tcred
->suid
)) {
2200 goto out_unlock_cgroup
;
2206 tsk
= tsk
->group_leader
;
2209 * Workqueue threads may acquire PF_THREAD_BOUND and become
2210 * trapped in a cpuset, or RT worker may be born in a cgroup
2211 * with no rt_runtime allocated. Just say no.
2213 if (tsk
== kthreadd_task
|| (tsk
->flags
& PF_THREAD_BOUND
)) {
2216 goto out_unlock_cgroup
;
2219 get_task_struct(tsk
);
2222 threadgroup_lock(tsk
);
2224 if (!thread_group_leader(tsk
)) {
2226 * a race with de_thread from another thread's exec()
2227 * may strip us of our leadership, if this happens,
2228 * there is no choice but to throw this task away and
2229 * try again; this is
2230 * "double-double-toil-and-trouble-check locking".
2232 threadgroup_unlock(tsk
);
2233 put_task_struct(tsk
);
2234 goto retry_find_task
;
2236 ret
= cgroup_attach_proc(cgrp
, tsk
);
2238 ret
= cgroup_attach_task(cgrp
, tsk
);
2239 threadgroup_unlock(tsk
);
2241 put_task_struct(tsk
);
2247 static int cgroup_tasks_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 pid
)
2249 return attach_task_by_pid(cgrp
, pid
, false);
2252 static int cgroup_procs_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 tgid
)
2254 return attach_task_by_pid(cgrp
, tgid
, true);
2258 * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
2259 * @cgrp: the cgroup to be checked for liveness
2261 * On success, returns true; the lock should be later released with
2262 * cgroup_unlock(). On failure returns false with no lock held.
2264 bool cgroup_lock_live_group(struct cgroup
*cgrp
)
2266 mutex_lock(&cgroup_mutex
);
2267 if (cgroup_is_removed(cgrp
)) {
2268 mutex_unlock(&cgroup_mutex
);
2273 EXPORT_SYMBOL_GPL(cgroup_lock_live_group
);
2275 static int cgroup_release_agent_write(struct cgroup
*cgrp
, struct cftype
*cft
,
2278 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
2279 if (strlen(buffer
) >= PATH_MAX
)
2281 if (!cgroup_lock_live_group(cgrp
))
2283 mutex_lock(&cgroup_root_mutex
);
2284 strcpy(cgrp
->root
->release_agent_path
, buffer
);
2285 mutex_unlock(&cgroup_root_mutex
);
2290 static int cgroup_release_agent_show(struct cgroup
*cgrp
, struct cftype
*cft
,
2291 struct seq_file
*seq
)
2293 if (!cgroup_lock_live_group(cgrp
))
2295 seq_puts(seq
, cgrp
->root
->release_agent_path
);
2296 seq_putc(seq
, '\n');
2301 /* A buffer size big enough for numbers or short strings */
2302 #define CGROUP_LOCAL_BUFFER_SIZE 64
2304 static ssize_t
cgroup_write_X64(struct cgroup
*cgrp
, struct cftype
*cft
,
2306 const char __user
*userbuf
,
2307 size_t nbytes
, loff_t
*unused_ppos
)
2309 char buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
2315 if (nbytes
>= sizeof(buffer
))
2317 if (copy_from_user(buffer
, userbuf
, nbytes
))
2320 buffer
[nbytes
] = 0; /* nul-terminate */
2321 if (cft
->write_u64
) {
2322 u64 val
= simple_strtoull(strstrip(buffer
), &end
, 0);
2325 retval
= cft
->write_u64(cgrp
, cft
, val
);
2327 s64 val
= simple_strtoll(strstrip(buffer
), &end
, 0);
2330 retval
= cft
->write_s64(cgrp
, cft
, val
);
2337 static ssize_t
cgroup_write_string(struct cgroup
*cgrp
, struct cftype
*cft
,
2339 const char __user
*userbuf
,
2340 size_t nbytes
, loff_t
*unused_ppos
)
2342 char local_buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
2344 size_t max_bytes
= cft
->max_write_len
;
2345 char *buffer
= local_buffer
;
2348 max_bytes
= sizeof(local_buffer
) - 1;
2349 if (nbytes
>= max_bytes
)
2351 /* Allocate a dynamic buffer if we need one */
2352 if (nbytes
>= sizeof(local_buffer
)) {
2353 buffer
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
2357 if (nbytes
&& copy_from_user(buffer
, userbuf
, nbytes
)) {
2362 buffer
[nbytes
] = 0; /* nul-terminate */
2363 retval
= cft
->write_string(cgrp
, cft
, strstrip(buffer
));
2367 if (buffer
!= local_buffer
)
2372 static ssize_t
cgroup_file_write(struct file
*file
, const char __user
*buf
,
2373 size_t nbytes
, loff_t
*ppos
)
2375 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2376 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2378 if (cgroup_is_removed(cgrp
))
2381 return cft
->write(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2382 if (cft
->write_u64
|| cft
->write_s64
)
2383 return cgroup_write_X64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2384 if (cft
->write_string
)
2385 return cgroup_write_string(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2387 int ret
= cft
->trigger(cgrp
, (unsigned int)cft
->private);
2388 return ret
? ret
: nbytes
;
2393 static ssize_t
cgroup_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
2395 char __user
*buf
, size_t nbytes
,
2398 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
2399 u64 val
= cft
->read_u64(cgrp
, cft
);
2400 int len
= sprintf(tmp
, "%llu\n", (unsigned long long) val
);
2402 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
2405 static ssize_t
cgroup_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
,
2407 char __user
*buf
, size_t nbytes
,
2410 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
2411 s64 val
= cft
->read_s64(cgrp
, cft
);
2412 int len
= sprintf(tmp
, "%lld\n", (long long) val
);
2414 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
2417 static ssize_t
cgroup_file_read(struct file
*file
, char __user
*buf
,
2418 size_t nbytes
, loff_t
*ppos
)
2420 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2421 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2423 if (cgroup_is_removed(cgrp
))
2427 return cft
->read(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2429 return cgroup_read_u64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2431 return cgroup_read_s64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2436 * seqfile ops/methods for returning structured data. Currently just
2437 * supports string->u64 maps, but can be extended in future.
2440 struct cgroup_seqfile_state
{
2442 struct cgroup
*cgroup
;
2445 static int cgroup_map_add(struct cgroup_map_cb
*cb
, const char *key
, u64 value
)
2447 struct seq_file
*sf
= cb
->state
;
2448 return seq_printf(sf
, "%s %llu\n", key
, (unsigned long long)value
);
2451 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
2453 struct cgroup_seqfile_state
*state
= m
->private;
2454 struct cftype
*cft
= state
->cft
;
2455 if (cft
->read_map
) {
2456 struct cgroup_map_cb cb
= {
2457 .fill
= cgroup_map_add
,
2460 return cft
->read_map(state
->cgroup
, cft
, &cb
);
2462 return cft
->read_seq_string(state
->cgroup
, cft
, m
);
2465 static int cgroup_seqfile_release(struct inode
*inode
, struct file
*file
)
2467 struct seq_file
*seq
= file
->private_data
;
2468 kfree(seq
->private);
2469 return single_release(inode
, file
);
2472 static const struct file_operations cgroup_seqfile_operations
= {
2474 .write
= cgroup_file_write
,
2475 .llseek
= seq_lseek
,
2476 .release
= cgroup_seqfile_release
,
2479 static int cgroup_file_open(struct inode
*inode
, struct file
*file
)
2484 err
= generic_file_open(inode
, file
);
2487 cft
= __d_cft(file
->f_dentry
);
2489 if (cft
->read_map
|| cft
->read_seq_string
) {
2490 struct cgroup_seqfile_state
*state
=
2491 kzalloc(sizeof(*state
), GFP_USER
);
2495 state
->cgroup
= __d_cgrp(file
->f_dentry
->d_parent
);
2496 file
->f_op
= &cgroup_seqfile_operations
;
2497 err
= single_open(file
, cgroup_seqfile_show
, state
);
2500 } else if (cft
->open
)
2501 err
= cft
->open(inode
, file
);
2508 static int cgroup_file_release(struct inode
*inode
, struct file
*file
)
2510 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2512 return cft
->release(inode
, file
);
2517 * cgroup_rename - Only allow simple rename of directories in place.
2519 static int cgroup_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2520 struct inode
*new_dir
, struct dentry
*new_dentry
)
2522 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
))
2524 if (new_dentry
->d_inode
)
2526 if (old_dir
!= new_dir
)
2528 return simple_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2531 static struct simple_xattrs
*__d_xattrs(struct dentry
*dentry
)
2533 if (S_ISDIR(dentry
->d_inode
->i_mode
))
2534 return &__d_cgrp(dentry
)->xattrs
;
2536 return &__d_cft(dentry
)->xattrs
;
2539 static inline int xattr_enabled(struct dentry
*dentry
)
2541 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
2542 return test_bit(ROOT_XATTR
, &root
->flags
);
2545 static bool is_valid_xattr(const char *name
)
2547 if (!strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
) ||
2548 !strncmp(name
, XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
))
2553 static int cgroup_setxattr(struct dentry
*dentry
, const char *name
,
2554 const void *val
, size_t size
, int flags
)
2556 if (!xattr_enabled(dentry
))
2558 if (!is_valid_xattr(name
))
2560 return simple_xattr_set(__d_xattrs(dentry
), name
, val
, size
, flags
);
2563 static int cgroup_removexattr(struct dentry
*dentry
, const char *name
)
2565 if (!xattr_enabled(dentry
))
2567 if (!is_valid_xattr(name
))
2569 return simple_xattr_remove(__d_xattrs(dentry
), name
);
2572 static ssize_t
cgroup_getxattr(struct dentry
*dentry
, const char *name
,
2573 void *buf
, size_t size
)
2575 if (!xattr_enabled(dentry
))
2577 if (!is_valid_xattr(name
))
2579 return simple_xattr_get(__d_xattrs(dentry
), name
, buf
, size
);
2582 static ssize_t
cgroup_listxattr(struct dentry
*dentry
, char *buf
, size_t size
)
2584 if (!xattr_enabled(dentry
))
2586 return simple_xattr_list(__d_xattrs(dentry
), buf
, size
);
2589 static const struct file_operations cgroup_file_operations
= {
2590 .read
= cgroup_file_read
,
2591 .write
= cgroup_file_write
,
2592 .llseek
= generic_file_llseek
,
2593 .open
= cgroup_file_open
,
2594 .release
= cgroup_file_release
,
2597 static const struct inode_operations cgroup_file_inode_operations
= {
2598 .setxattr
= cgroup_setxattr
,
2599 .getxattr
= cgroup_getxattr
,
2600 .listxattr
= cgroup_listxattr
,
2601 .removexattr
= cgroup_removexattr
,
2604 static const struct inode_operations cgroup_dir_inode_operations
= {
2605 .lookup
= cgroup_lookup
,
2606 .mkdir
= cgroup_mkdir
,
2607 .rmdir
= cgroup_rmdir
,
2608 .rename
= cgroup_rename
,
2609 .setxattr
= cgroup_setxattr
,
2610 .getxattr
= cgroup_getxattr
,
2611 .listxattr
= cgroup_listxattr
,
2612 .removexattr
= cgroup_removexattr
,
2615 static struct dentry
*cgroup_lookup(struct inode
*dir
, struct dentry
*dentry
, unsigned int flags
)
2617 if (dentry
->d_name
.len
> NAME_MAX
)
2618 return ERR_PTR(-ENAMETOOLONG
);
2619 d_add(dentry
, NULL
);
2624 * Check if a file is a control file
2626 static inline struct cftype
*__file_cft(struct file
*file
)
2628 if (file
->f_dentry
->d_inode
->i_fop
!= &cgroup_file_operations
)
2629 return ERR_PTR(-EINVAL
);
2630 return __d_cft(file
->f_dentry
);
2633 static int cgroup_create_file(struct dentry
*dentry
, umode_t mode
,
2634 struct super_block
*sb
)
2636 struct inode
*inode
;
2640 if (dentry
->d_inode
)
2643 inode
= cgroup_new_inode(mode
, sb
);
2647 if (S_ISDIR(mode
)) {
2648 inode
->i_op
= &cgroup_dir_inode_operations
;
2649 inode
->i_fop
= &simple_dir_operations
;
2651 /* start off with i_nlink == 2 (for "." entry) */
2653 inc_nlink(dentry
->d_parent
->d_inode
);
2656 * Control reaches here with cgroup_mutex held.
2657 * @inode->i_mutex should nest outside cgroup_mutex but we
2658 * want to populate it immediately without releasing
2659 * cgroup_mutex. As @inode isn't visible to anyone else
2660 * yet, trylock will always succeed without affecting
2663 WARN_ON_ONCE(!mutex_trylock(&inode
->i_mutex
));
2664 } else if (S_ISREG(mode
)) {
2666 inode
->i_fop
= &cgroup_file_operations
;
2667 inode
->i_op
= &cgroup_file_inode_operations
;
2669 d_instantiate(dentry
, inode
);
2670 dget(dentry
); /* Extra count - pin the dentry in core */
2675 * cgroup_file_mode - deduce file mode of a control file
2676 * @cft: the control file in question
2678 * returns cft->mode if ->mode is not 0
2679 * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
2680 * returns S_IRUGO if it has only a read handler
2681 * returns S_IWUSR if it has only a write hander
2683 static umode_t
cgroup_file_mode(const struct cftype
*cft
)
2690 if (cft
->read
|| cft
->read_u64
|| cft
->read_s64
||
2691 cft
->read_map
|| cft
->read_seq_string
)
2694 if (cft
->write
|| cft
->write_u64
|| cft
->write_s64
||
2695 cft
->write_string
|| cft
->trigger
)
2701 static int cgroup_add_file(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
2704 struct dentry
*dir
= cgrp
->dentry
;
2705 struct cgroup
*parent
= __d_cgrp(dir
);
2706 struct dentry
*dentry
;
2710 char name
[MAX_CGROUP_TYPE_NAMELEN
+ MAX_CFTYPE_NAME
+ 2] = { 0 };
2712 simple_xattrs_init(&cft
->xattrs
);
2714 /* does @cft->flags tell us to skip creation on @cgrp? */
2715 if ((cft
->flags
& CFTYPE_NOT_ON_ROOT
) && !cgrp
->parent
)
2717 if ((cft
->flags
& CFTYPE_ONLY_ON_ROOT
) && cgrp
->parent
)
2720 if (subsys
&& !test_bit(ROOT_NOPREFIX
, &cgrp
->root
->flags
)) {
2721 strcpy(name
, subsys
->name
);
2724 strcat(name
, cft
->name
);
2726 BUG_ON(!mutex_is_locked(&dir
->d_inode
->i_mutex
));
2728 cfe
= kzalloc(sizeof(*cfe
), GFP_KERNEL
);
2732 dentry
= lookup_one_len(name
, dir
, strlen(name
));
2733 if (IS_ERR(dentry
)) {
2734 error
= PTR_ERR(dentry
);
2738 mode
= cgroup_file_mode(cft
);
2739 error
= cgroup_create_file(dentry
, mode
| S_IFREG
, cgrp
->root
->sb
);
2741 cfe
->type
= (void *)cft
;
2742 cfe
->dentry
= dentry
;
2743 dentry
->d_fsdata
= cfe
;
2744 list_add_tail(&cfe
->node
, &parent
->files
);
2753 static int cgroup_addrm_files(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
2754 struct cftype cfts
[], bool is_add
)
2759 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
2761 err
= cgroup_add_file(cgrp
, subsys
, cft
);
2763 err
= cgroup_rm_file(cgrp
, cft
);
2765 pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n",
2766 is_add
? "add" : "remove", cft
->name
, err
);
2773 static DEFINE_MUTEX(cgroup_cft_mutex
);
2775 static void cgroup_cfts_prepare(void)
2776 __acquires(&cgroup_cft_mutex
) __acquires(&cgroup_mutex
)
2779 * Thanks to the entanglement with vfs inode locking, we can't walk
2780 * the existing cgroups under cgroup_mutex and create files.
2781 * Instead, we increment reference on all cgroups and build list of
2782 * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure
2783 * exclusive access to the field.
2785 mutex_lock(&cgroup_cft_mutex
);
2786 mutex_lock(&cgroup_mutex
);
2789 static void cgroup_cfts_commit(struct cgroup_subsys
*ss
,
2790 struct cftype
*cfts
, bool is_add
)
2791 __releases(&cgroup_mutex
) __releases(&cgroup_cft_mutex
)
2794 struct cgroup
*cgrp
, *n
;
2796 /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
2797 if (cfts
&& ss
->root
!= &rootnode
) {
2798 list_for_each_entry(cgrp
, &ss
->root
->allcg_list
, allcg_node
) {
2800 list_add_tail(&cgrp
->cft_q_node
, &pending
);
2804 mutex_unlock(&cgroup_mutex
);
2807 * All new cgroups will see @cfts update on @ss->cftsets. Add/rm
2808 * files for all cgroups which were created before.
2810 list_for_each_entry_safe(cgrp
, n
, &pending
, cft_q_node
) {
2811 struct inode
*inode
= cgrp
->dentry
->d_inode
;
2813 mutex_lock(&inode
->i_mutex
);
2814 mutex_lock(&cgroup_mutex
);
2815 if (!cgroup_is_removed(cgrp
))
2816 cgroup_addrm_files(cgrp
, ss
, cfts
, is_add
);
2817 mutex_unlock(&cgroup_mutex
);
2818 mutex_unlock(&inode
->i_mutex
);
2820 list_del_init(&cgrp
->cft_q_node
);
2824 mutex_unlock(&cgroup_cft_mutex
);
2828 * cgroup_add_cftypes - add an array of cftypes to a subsystem
2829 * @ss: target cgroup subsystem
2830 * @cfts: zero-length name terminated array of cftypes
2832 * Register @cfts to @ss. Files described by @cfts are created for all
2833 * existing cgroups to which @ss is attached and all future cgroups will
2834 * have them too. This function can be called anytime whether @ss is
2837 * Returns 0 on successful registration, -errno on failure. Note that this
2838 * function currently returns 0 as long as @cfts registration is successful
2839 * even if some file creation attempts on existing cgroups fail.
2841 int cgroup_add_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2843 struct cftype_set
*set
;
2845 set
= kzalloc(sizeof(*set
), GFP_KERNEL
);
2849 cgroup_cfts_prepare();
2851 list_add_tail(&set
->node
, &ss
->cftsets
);
2852 cgroup_cfts_commit(ss
, cfts
, true);
2856 EXPORT_SYMBOL_GPL(cgroup_add_cftypes
);
2859 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
2860 * @ss: target cgroup subsystem
2861 * @cfts: zero-length name terminated array of cftypes
2863 * Unregister @cfts from @ss. Files described by @cfts are removed from
2864 * all existing cgroups to which @ss is attached and all future cgroups
2865 * won't have them either. This function can be called anytime whether @ss
2866 * is attached or not.
2868 * Returns 0 on successful unregistration, -ENOENT if @cfts is not
2869 * registered with @ss.
2871 int cgroup_rm_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2873 struct cftype_set
*set
;
2875 cgroup_cfts_prepare();
2877 list_for_each_entry(set
, &ss
->cftsets
, node
) {
2878 if (set
->cfts
== cfts
) {
2879 list_del_init(&set
->node
);
2880 cgroup_cfts_commit(ss
, cfts
, false);
2885 cgroup_cfts_commit(ss
, NULL
, false);
2890 * cgroup_task_count - count the number of tasks in a cgroup.
2891 * @cgrp: the cgroup in question
2893 * Return the number of tasks in the cgroup.
2895 int cgroup_task_count(const struct cgroup
*cgrp
)
2898 struct cg_cgroup_link
*link
;
2900 read_lock(&css_set_lock
);
2901 list_for_each_entry(link
, &cgrp
->css_sets
, cgrp_link_list
) {
2902 count
+= atomic_read(&link
->cg
->refcount
);
2904 read_unlock(&css_set_lock
);
2909 * Advance a list_head iterator. The iterator should be positioned at
2910 * the start of a css_set
2912 static void cgroup_advance_iter(struct cgroup
*cgrp
,
2913 struct cgroup_iter
*it
)
2915 struct list_head
*l
= it
->cg_link
;
2916 struct cg_cgroup_link
*link
;
2919 /* Advance to the next non-empty css_set */
2922 if (l
== &cgrp
->css_sets
) {
2926 link
= list_entry(l
, struct cg_cgroup_link
, cgrp_link_list
);
2928 } while (list_empty(&cg
->tasks
));
2930 it
->task
= cg
->tasks
.next
;
2934 * To reduce the fork() overhead for systems that are not actually
2935 * using their cgroups capability, we don't maintain the lists running
2936 * through each css_set to its tasks until we see the list actually
2937 * used - in other words after the first call to cgroup_iter_start().
2939 static void cgroup_enable_task_cg_lists(void)
2941 struct task_struct
*p
, *g
;
2942 write_lock(&css_set_lock
);
2943 use_task_css_set_links
= 1;
2945 * We need tasklist_lock because RCU is not safe against
2946 * while_each_thread(). Besides, a forking task that has passed
2947 * cgroup_post_fork() without seeing use_task_css_set_links = 1
2948 * is not guaranteed to have its child immediately visible in the
2949 * tasklist if we walk through it with RCU.
2951 read_lock(&tasklist_lock
);
2952 do_each_thread(g
, p
) {
2955 * We should check if the process is exiting, otherwise
2956 * it will race with cgroup_exit() in that the list
2957 * entry won't be deleted though the process has exited.
2959 if (!(p
->flags
& PF_EXITING
) && list_empty(&p
->cg_list
))
2960 list_add(&p
->cg_list
, &p
->cgroups
->tasks
);
2962 } while_each_thread(g
, p
);
2963 read_unlock(&tasklist_lock
);
2964 write_unlock(&css_set_lock
);
2968 * cgroup_next_descendant_pre - find the next descendant for pre-order walk
2969 * @pos: the current position (%NULL to initiate traversal)
2970 * @cgroup: cgroup whose descendants to walk
2972 * To be used by cgroup_for_each_descendant_pre(). Find the next
2973 * descendant to visit for pre-order traversal of @cgroup's descendants.
2975 struct cgroup
*cgroup_next_descendant_pre(struct cgroup
*pos
,
2976 struct cgroup
*cgroup
)
2978 struct cgroup
*next
;
2980 WARN_ON_ONCE(!rcu_read_lock_held());
2982 /* if first iteration, pretend we just visited @cgroup */
2984 if (list_empty(&cgroup
->children
))
2989 /* visit the first child if exists */
2990 next
= list_first_or_null_rcu(&pos
->children
, struct cgroup
, sibling
);
2994 /* no child, visit my or the closest ancestor's next sibling */
2996 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup
,
2998 if (&next
->sibling
!= &pos
->parent
->children
)
3002 } while (pos
!= cgroup
);
3006 EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre
);
3008 static struct cgroup
*cgroup_leftmost_descendant(struct cgroup
*pos
)
3010 struct cgroup
*last
;
3014 pos
= list_first_or_null_rcu(&pos
->children
, struct cgroup
,
3022 * cgroup_next_descendant_post - find the next descendant for post-order walk
3023 * @pos: the current position (%NULL to initiate traversal)
3024 * @cgroup: cgroup whose descendants to walk
3026 * To be used by cgroup_for_each_descendant_post(). Find the next
3027 * descendant to visit for post-order traversal of @cgroup's descendants.
3029 struct cgroup
*cgroup_next_descendant_post(struct cgroup
*pos
,
3030 struct cgroup
*cgroup
)
3032 struct cgroup
*next
;
3034 WARN_ON_ONCE(!rcu_read_lock_held());
3036 /* if first iteration, visit the leftmost descendant */
3038 next
= cgroup_leftmost_descendant(cgroup
);
3039 return next
!= cgroup
? next
: NULL
;
3042 /* if there's an unvisited sibling, visit its leftmost descendant */
3043 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup
, sibling
);
3044 if (&next
->sibling
!= &pos
->parent
->children
)
3045 return cgroup_leftmost_descendant(next
);
3047 /* no sibling left, visit parent */
3049 return next
!= cgroup
? next
: NULL
;
3051 EXPORT_SYMBOL_GPL(cgroup_next_descendant_post
);
3053 void cgroup_iter_start(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
3054 __acquires(css_set_lock
)
3057 * The first time anyone tries to iterate across a cgroup,
3058 * we need to enable the list linking each css_set to its
3059 * tasks, and fix up all existing tasks.
3061 if (!use_task_css_set_links
)
3062 cgroup_enable_task_cg_lists();
3064 read_lock(&css_set_lock
);
3065 it
->cg_link
= &cgrp
->css_sets
;
3066 cgroup_advance_iter(cgrp
, it
);
3069 struct task_struct
*cgroup_iter_next(struct cgroup
*cgrp
,
3070 struct cgroup_iter
*it
)
3072 struct task_struct
*res
;
3073 struct list_head
*l
= it
->task
;
3074 struct cg_cgroup_link
*link
;
3076 /* If the iterator cg is NULL, we have no tasks */
3079 res
= list_entry(l
, struct task_struct
, cg_list
);
3080 /* Advance iterator to find next entry */
3082 link
= list_entry(it
->cg_link
, struct cg_cgroup_link
, cgrp_link_list
);
3083 if (l
== &link
->cg
->tasks
) {
3084 /* We reached the end of this task list - move on to
3085 * the next cg_cgroup_link */
3086 cgroup_advance_iter(cgrp
, it
);
3093 void cgroup_iter_end(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
3094 __releases(css_set_lock
)
3096 read_unlock(&css_set_lock
);
3099 static inline int started_after_time(struct task_struct
*t1
,
3100 struct timespec
*time
,
3101 struct task_struct
*t2
)
3103 int start_diff
= timespec_compare(&t1
->start_time
, time
);
3104 if (start_diff
> 0) {
3106 } else if (start_diff
< 0) {
3110 * Arbitrarily, if two processes started at the same
3111 * time, we'll say that the lower pointer value
3112 * started first. Note that t2 may have exited by now
3113 * so this may not be a valid pointer any longer, but
3114 * that's fine - it still serves to distinguish
3115 * between two tasks started (effectively) simultaneously.
3122 * This function is a callback from heap_insert() and is used to order
3124 * In this case we order the heap in descending task start time.
3126 static inline int started_after(void *p1
, void *p2
)
3128 struct task_struct
*t1
= p1
;
3129 struct task_struct
*t2
= p2
;
3130 return started_after_time(t1
, &t2
->start_time
, t2
);
3134 * cgroup_scan_tasks - iterate though all the tasks in a cgroup
3135 * @scan: struct cgroup_scanner containing arguments for the scan
3137 * Arguments include pointers to callback functions test_task() and
3139 * Iterate through all the tasks in a cgroup, calling test_task() for each,
3140 * and if it returns true, call process_task() for it also.
3141 * The test_task pointer may be NULL, meaning always true (select all tasks).
3142 * Effectively duplicates cgroup_iter_{start,next,end}()
3143 * but does not lock css_set_lock for the call to process_task().
3144 * The struct cgroup_scanner may be embedded in any structure of the caller's
3146 * It is guaranteed that process_task() will act on every task that
3147 * is a member of the cgroup for the duration of this call. This
3148 * function may or may not call process_task() for tasks that exit
3149 * or move to a different cgroup during the call, or are forked or
3150 * move into the cgroup during the call.
3152 * Note that test_task() may be called with locks held, and may in some
3153 * situations be called multiple times for the same task, so it should
3155 * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
3156 * pre-allocated and will be used for heap operations (and its "gt" member will
3157 * be overwritten), else a temporary heap will be used (allocation of which
3158 * may cause this function to fail).
3160 int cgroup_scan_tasks(struct cgroup_scanner
*scan
)
3163 struct cgroup_iter it
;
3164 struct task_struct
*p
, *dropped
;
3165 /* Never dereference latest_task, since it's not refcounted */
3166 struct task_struct
*latest_task
= NULL
;
3167 struct ptr_heap tmp_heap
;
3168 struct ptr_heap
*heap
;
3169 struct timespec latest_time
= { 0, 0 };
3172 /* The caller supplied our heap and pre-allocated its memory */
3174 heap
->gt
= &started_after
;
3176 /* We need to allocate our own heap memory */
3178 retval
= heap_init(heap
, PAGE_SIZE
, GFP_KERNEL
, &started_after
);
3180 /* cannot allocate the heap */
3186 * Scan tasks in the cgroup, using the scanner's "test_task" callback
3187 * to determine which are of interest, and using the scanner's
3188 * "process_task" callback to process any of them that need an update.
3189 * Since we don't want to hold any locks during the task updates,
3190 * gather tasks to be processed in a heap structure.
3191 * The heap is sorted by descending task start time.
3192 * If the statically-sized heap fills up, we overflow tasks that
3193 * started later, and in future iterations only consider tasks that
3194 * started after the latest task in the previous pass. This
3195 * guarantees forward progress and that we don't miss any tasks.
3198 cgroup_iter_start(scan
->cg
, &it
);
3199 while ((p
= cgroup_iter_next(scan
->cg
, &it
))) {
3201 * Only affect tasks that qualify per the caller's callback,
3202 * if he provided one
3204 if (scan
->test_task
&& !scan
->test_task(p
, scan
))
3207 * Only process tasks that started after the last task
3210 if (!started_after_time(p
, &latest_time
, latest_task
))
3212 dropped
= heap_insert(heap
, p
);
3213 if (dropped
== NULL
) {
3215 * The new task was inserted; the heap wasn't
3219 } else if (dropped
!= p
) {
3221 * The new task was inserted, and pushed out a
3225 put_task_struct(dropped
);
3228 * Else the new task was newer than anything already in
3229 * the heap and wasn't inserted
3232 cgroup_iter_end(scan
->cg
, &it
);
3235 for (i
= 0; i
< heap
->size
; i
++) {
3236 struct task_struct
*q
= heap
->ptrs
[i
];
3238 latest_time
= q
->start_time
;
3241 /* Process the task per the caller's callback */
3242 scan
->process_task(q
, scan
);
3246 * If we had to process any tasks at all, scan again
3247 * in case some of them were in the middle of forking
3248 * children that didn't get processed.
3249 * Not the most efficient way to do it, but it avoids
3250 * having to take callback_mutex in the fork path
3254 if (heap
== &tmp_heap
)
3255 heap_free(&tmp_heap
);
3260 * Stuff for reading the 'tasks'/'procs' files.
3262 * Reading this file can return large amounts of data if a cgroup has
3263 * *lots* of attached tasks. So it may need several calls to read(),
3264 * but we cannot guarantee that the information we produce is correct
3265 * unless we produce it entirely atomically.
3269 /* which pidlist file are we talking about? */
3270 enum cgroup_filetype
{
3276 * A pidlist is a list of pids that virtually represents the contents of one
3277 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
3278 * a pair (one each for procs, tasks) for each pid namespace that's relevant
3281 struct cgroup_pidlist
{
3283 * used to find which pidlist is wanted. doesn't change as long as
3284 * this particular list stays in the list.
3286 struct { enum cgroup_filetype type
; struct pid_namespace
*ns
; } key
;
3289 /* how many elements the above list has */
3291 /* how many files are using the current array */
3293 /* each of these stored in a list by its cgroup */
3294 struct list_head links
;
3295 /* pointer to the cgroup we belong to, for list removal purposes */
3296 struct cgroup
*owner
;
3297 /* protects the other fields */
3298 struct rw_semaphore mutex
;
3302 * The following two functions "fix" the issue where there are more pids
3303 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
3304 * TODO: replace with a kernel-wide solution to this problem
3306 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
3307 static void *pidlist_allocate(int count
)
3309 if (PIDLIST_TOO_LARGE(count
))
3310 return vmalloc(count
* sizeof(pid_t
));
3312 return kmalloc(count
* sizeof(pid_t
), GFP_KERNEL
);
3314 static void pidlist_free(void *p
)
3316 if (is_vmalloc_addr(p
))
3321 static void *pidlist_resize(void *p
, int newcount
)
3324 /* note: if new alloc fails, old p will still be valid either way */
3325 if (is_vmalloc_addr(p
)) {
3326 newlist
= vmalloc(newcount
* sizeof(pid_t
));
3329 memcpy(newlist
, p
, newcount
* sizeof(pid_t
));
3332 newlist
= krealloc(p
, newcount
* sizeof(pid_t
), GFP_KERNEL
);
3338 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
3339 * If the new stripped list is sufficiently smaller and there's enough memory
3340 * to allocate a new buffer, will let go of the unneeded memory. Returns the
3341 * number of unique elements.
3343 /* is the size difference enough that we should re-allocate the array? */
3344 #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new))
3345 static int pidlist_uniq(pid_t
**p
, int length
)
3352 * we presume the 0th element is unique, so i starts at 1. trivial
3353 * edge cases first; no work needs to be done for either
3355 if (length
== 0 || length
== 1)
3357 /* src and dest walk down the list; dest counts unique elements */
3358 for (src
= 1; src
< length
; src
++) {
3359 /* find next unique element */
3360 while (list
[src
] == list
[src
-1]) {
3365 /* dest always points to where the next unique element goes */
3366 list
[dest
] = list
[src
];
3371 * if the length difference is large enough, we want to allocate a
3372 * smaller buffer to save memory. if this fails due to out of memory,
3373 * we'll just stay with what we've got.
3375 if (PIDLIST_REALLOC_DIFFERENCE(length
, dest
)) {
3376 newlist
= pidlist_resize(list
, dest
);
3383 static int cmppid(const void *a
, const void *b
)
3385 return *(pid_t
*)a
- *(pid_t
*)b
;
3389 * find the appropriate pidlist for our purpose (given procs vs tasks)
3390 * returns with the lock on that pidlist already held, and takes care
3391 * of the use count, or returns NULL with no locks held if we're out of
3394 static struct cgroup_pidlist
*cgroup_pidlist_find(struct cgroup
*cgrp
,
3395 enum cgroup_filetype type
)
3397 struct cgroup_pidlist
*l
;
3398 /* don't need task_nsproxy() if we're looking at ourself */
3399 struct pid_namespace
*ns
= current
->nsproxy
->pid_ns
;
3402 * We can't drop the pidlist_mutex before taking the l->mutex in case
3403 * the last ref-holder is trying to remove l from the list at the same
3404 * time. Holding the pidlist_mutex precludes somebody taking whichever
3405 * list we find out from under us - compare release_pid_array().
3407 mutex_lock(&cgrp
->pidlist_mutex
);
3408 list_for_each_entry(l
, &cgrp
->pidlists
, links
) {
3409 if (l
->key
.type
== type
&& l
->key
.ns
== ns
) {
3410 /* make sure l doesn't vanish out from under us */
3411 down_write(&l
->mutex
);
3412 mutex_unlock(&cgrp
->pidlist_mutex
);
3416 /* entry not found; create a new one */
3417 l
= kmalloc(sizeof(struct cgroup_pidlist
), GFP_KERNEL
);
3419 mutex_unlock(&cgrp
->pidlist_mutex
);
3422 init_rwsem(&l
->mutex
);
3423 down_write(&l
->mutex
);
3425 l
->key
.ns
= get_pid_ns(ns
);
3426 l
->use_count
= 0; /* don't increment here */
3429 list_add(&l
->links
, &cgrp
->pidlists
);
3430 mutex_unlock(&cgrp
->pidlist_mutex
);
3435 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
3437 static int pidlist_array_load(struct cgroup
*cgrp
, enum cgroup_filetype type
,
3438 struct cgroup_pidlist
**lp
)
3442 int pid
, n
= 0; /* used for populating the array */
3443 struct cgroup_iter it
;
3444 struct task_struct
*tsk
;
3445 struct cgroup_pidlist
*l
;
3448 * If cgroup gets more users after we read count, we won't have
3449 * enough space - tough. This race is indistinguishable to the
3450 * caller from the case that the additional cgroup users didn't
3451 * show up until sometime later on.
3453 length
= cgroup_task_count(cgrp
);
3454 array
= pidlist_allocate(length
);
3457 /* now, populate the array */
3458 cgroup_iter_start(cgrp
, &it
);
3459 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
3460 if (unlikely(n
== length
))
3462 /* get tgid or pid for procs or tasks file respectively */
3463 if (type
== CGROUP_FILE_PROCS
)
3464 pid
= task_tgid_vnr(tsk
);
3466 pid
= task_pid_vnr(tsk
);
3467 if (pid
> 0) /* make sure to only use valid results */
3470 cgroup_iter_end(cgrp
, &it
);
3472 /* now sort & (if procs) strip out duplicates */
3473 sort(array
, length
, sizeof(pid_t
), cmppid
, NULL
);
3474 if (type
== CGROUP_FILE_PROCS
)
3475 length
= pidlist_uniq(&array
, length
);
3476 l
= cgroup_pidlist_find(cgrp
, type
);
3478 pidlist_free(array
);
3481 /* store array, freeing old if necessary - lock already held */
3482 pidlist_free(l
->list
);
3486 up_write(&l
->mutex
);
3492 * cgroupstats_build - build and fill cgroupstats
3493 * @stats: cgroupstats to fill information into
3494 * @dentry: A dentry entry belonging to the cgroup for which stats have
3497 * Build and fill cgroupstats so that taskstats can export it to user
3500 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
3503 struct cgroup
*cgrp
;
3504 struct cgroup_iter it
;
3505 struct task_struct
*tsk
;
3508 * Validate dentry by checking the superblock operations,
3509 * and make sure it's a directory.
3511 if (dentry
->d_sb
->s_op
!= &cgroup_ops
||
3512 !S_ISDIR(dentry
->d_inode
->i_mode
))
3516 cgrp
= dentry
->d_fsdata
;
3518 cgroup_iter_start(cgrp
, &it
);
3519 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
3520 switch (tsk
->state
) {
3522 stats
->nr_running
++;
3524 case TASK_INTERRUPTIBLE
:
3525 stats
->nr_sleeping
++;
3527 case TASK_UNINTERRUPTIBLE
:
3528 stats
->nr_uninterruptible
++;
3531 stats
->nr_stopped
++;
3534 if (delayacct_is_task_waiting_on_io(tsk
))
3535 stats
->nr_io_wait
++;
3539 cgroup_iter_end(cgrp
, &it
);
3547 * seq_file methods for the tasks/procs files. The seq_file position is the
3548 * next pid to display; the seq_file iterator is a pointer to the pid
3549 * in the cgroup->l->list array.
3552 static void *cgroup_pidlist_start(struct seq_file
*s
, loff_t
*pos
)
3555 * Initially we receive a position value that corresponds to
3556 * one more than the last pid shown (or 0 on the first call or
3557 * after a seek to the start). Use a binary-search to find the
3558 * next pid to display, if any
3560 struct cgroup_pidlist
*l
= s
->private;
3561 int index
= 0, pid
= *pos
;
3564 down_read(&l
->mutex
);
3566 int end
= l
->length
;
3568 while (index
< end
) {
3569 int mid
= (index
+ end
) / 2;
3570 if (l
->list
[mid
] == pid
) {
3573 } else if (l
->list
[mid
] <= pid
)
3579 /* If we're off the end of the array, we're done */
3580 if (index
>= l
->length
)
3582 /* Update the abstract position to be the actual pid that we found */
3583 iter
= l
->list
+ index
;
3588 static void cgroup_pidlist_stop(struct seq_file
*s
, void *v
)
3590 struct cgroup_pidlist
*l
= s
->private;
3594 static void *cgroup_pidlist_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
3596 struct cgroup_pidlist
*l
= s
->private;
3598 pid_t
*end
= l
->list
+ l
->length
;
3600 * Advance to the next pid in the array. If this goes off the
3612 static int cgroup_pidlist_show(struct seq_file
*s
, void *v
)
3614 return seq_printf(s
, "%d\n", *(int *)v
);
3618 * seq_operations functions for iterating on pidlists through seq_file -
3619 * independent of whether it's tasks or procs
3621 static const struct seq_operations cgroup_pidlist_seq_operations
= {
3622 .start
= cgroup_pidlist_start
,
3623 .stop
= cgroup_pidlist_stop
,
3624 .next
= cgroup_pidlist_next
,
3625 .show
= cgroup_pidlist_show
,
3628 static void cgroup_release_pid_array(struct cgroup_pidlist
*l
)
3631 * the case where we're the last user of this particular pidlist will
3632 * have us remove it from the cgroup's list, which entails taking the
3633 * mutex. since in pidlist_find the pidlist->lock depends on cgroup->
3634 * pidlist_mutex, we have to take pidlist_mutex first.
3636 mutex_lock(&l
->owner
->pidlist_mutex
);
3637 down_write(&l
->mutex
);
3638 BUG_ON(!l
->use_count
);
3639 if (!--l
->use_count
) {
3640 /* we're the last user if refcount is 0; remove and free */
3641 list_del(&l
->links
);
3642 mutex_unlock(&l
->owner
->pidlist_mutex
);
3643 pidlist_free(l
->list
);
3644 put_pid_ns(l
->key
.ns
);
3645 up_write(&l
->mutex
);
3649 mutex_unlock(&l
->owner
->pidlist_mutex
);
3650 up_write(&l
->mutex
);
3653 static int cgroup_pidlist_release(struct inode
*inode
, struct file
*file
)
3655 struct cgroup_pidlist
*l
;
3656 if (!(file
->f_mode
& FMODE_READ
))
3659 * the seq_file will only be initialized if the file was opened for
3660 * reading; hence we check if it's not null only in that case.
3662 l
= ((struct seq_file
*)file
->private_data
)->private;
3663 cgroup_release_pid_array(l
);
3664 return seq_release(inode
, file
);
3667 static const struct file_operations cgroup_pidlist_operations
= {
3669 .llseek
= seq_lseek
,
3670 .write
= cgroup_file_write
,
3671 .release
= cgroup_pidlist_release
,
3675 * The following functions handle opens on a file that displays a pidlist
3676 * (tasks or procs). Prepare an array of the process/thread IDs of whoever's
3679 /* helper function for the two below it */
3680 static int cgroup_pidlist_open(struct file
*file
, enum cgroup_filetype type
)
3682 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
3683 struct cgroup_pidlist
*l
;
3686 /* Nothing to do for write-only files */
3687 if (!(file
->f_mode
& FMODE_READ
))
3690 /* have the array populated */
3691 retval
= pidlist_array_load(cgrp
, type
, &l
);
3694 /* configure file information */
3695 file
->f_op
= &cgroup_pidlist_operations
;
3697 retval
= seq_open(file
, &cgroup_pidlist_seq_operations
);
3699 cgroup_release_pid_array(l
);
3702 ((struct seq_file
*)file
->private_data
)->private = l
;
3705 static int cgroup_tasks_open(struct inode
*unused
, struct file
*file
)
3707 return cgroup_pidlist_open(file
, CGROUP_FILE_TASKS
);
3709 static int cgroup_procs_open(struct inode
*unused
, struct file
*file
)
3711 return cgroup_pidlist_open(file
, CGROUP_FILE_PROCS
);
3714 static u64
cgroup_read_notify_on_release(struct cgroup
*cgrp
,
3717 return notify_on_release(cgrp
);
3720 static int cgroup_write_notify_on_release(struct cgroup
*cgrp
,
3724 clear_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
3726 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3728 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3733 * Unregister event and free resources.
3735 * Gets called from workqueue.
3737 static void cgroup_event_remove(struct work_struct
*work
)
3739 struct cgroup_event
*event
= container_of(work
, struct cgroup_event
,
3741 struct cgroup
*cgrp
= event
->cgrp
;
3743 event
->cft
->unregister_event(cgrp
, event
->cft
, event
->eventfd
);
3745 eventfd_ctx_put(event
->eventfd
);
3751 * Gets called on POLLHUP on eventfd when user closes it.
3753 * Called with wqh->lock held and interrupts disabled.
3755 static int cgroup_event_wake(wait_queue_t
*wait
, unsigned mode
,
3756 int sync
, void *key
)
3758 struct cgroup_event
*event
= container_of(wait
,
3759 struct cgroup_event
, wait
);
3760 struct cgroup
*cgrp
= event
->cgrp
;
3761 unsigned long flags
= (unsigned long)key
;
3763 if (flags
& POLLHUP
) {
3764 __remove_wait_queue(event
->wqh
, &event
->wait
);
3765 spin_lock(&cgrp
->event_list_lock
);
3766 list_del(&event
->list
);
3767 spin_unlock(&cgrp
->event_list_lock
);
3769 * We are in atomic context, but cgroup_event_remove() may
3770 * sleep, so we have to call it in workqueue.
3772 schedule_work(&event
->remove
);
3778 static void cgroup_event_ptable_queue_proc(struct file
*file
,
3779 wait_queue_head_t
*wqh
, poll_table
*pt
)
3781 struct cgroup_event
*event
= container_of(pt
,
3782 struct cgroup_event
, pt
);
3785 add_wait_queue(wqh
, &event
->wait
);
3789 * Parse input and register new cgroup event handler.
3791 * Input must be in format '<event_fd> <control_fd> <args>'.
3792 * Interpretation of args is defined by control file implementation.
3794 static int cgroup_write_event_control(struct cgroup
*cgrp
, struct cftype
*cft
,
3797 struct cgroup_event
*event
= NULL
;
3798 unsigned int efd
, cfd
;
3799 struct file
*efile
= NULL
;
3800 struct file
*cfile
= NULL
;
3804 efd
= simple_strtoul(buffer
, &endp
, 10);
3809 cfd
= simple_strtoul(buffer
, &endp
, 10);
3810 if ((*endp
!= ' ') && (*endp
!= '\0'))
3814 event
= kzalloc(sizeof(*event
), GFP_KERNEL
);
3818 INIT_LIST_HEAD(&event
->list
);
3819 init_poll_funcptr(&event
->pt
, cgroup_event_ptable_queue_proc
);
3820 init_waitqueue_func_entry(&event
->wait
, cgroup_event_wake
);
3821 INIT_WORK(&event
->remove
, cgroup_event_remove
);
3823 efile
= eventfd_fget(efd
);
3824 if (IS_ERR(efile
)) {
3825 ret
= PTR_ERR(efile
);
3829 event
->eventfd
= eventfd_ctx_fileget(efile
);
3830 if (IS_ERR(event
->eventfd
)) {
3831 ret
= PTR_ERR(event
->eventfd
);
3841 /* the process need read permission on control file */
3842 /* AV: shouldn't we check that it's been opened for read instead? */
3843 ret
= inode_permission(cfile
->f_path
.dentry
->d_inode
, MAY_READ
);
3847 event
->cft
= __file_cft(cfile
);
3848 if (IS_ERR(event
->cft
)) {
3849 ret
= PTR_ERR(event
->cft
);
3853 if (!event
->cft
->register_event
|| !event
->cft
->unregister_event
) {
3858 ret
= event
->cft
->register_event(cgrp
, event
->cft
,
3859 event
->eventfd
, buffer
);
3863 if (efile
->f_op
->poll(efile
, &event
->pt
) & POLLHUP
) {
3864 event
->cft
->unregister_event(cgrp
, event
->cft
, event
->eventfd
);
3870 * Events should be removed after rmdir of cgroup directory, but before
3871 * destroying subsystem state objects. Let's take reference to cgroup
3872 * directory dentry to do that.
3876 spin_lock(&cgrp
->event_list_lock
);
3877 list_add(&event
->list
, &cgrp
->event_list
);
3878 spin_unlock(&cgrp
->event_list_lock
);
3889 if (event
&& event
->eventfd
&& !IS_ERR(event
->eventfd
))
3890 eventfd_ctx_put(event
->eventfd
);
3892 if (!IS_ERR_OR_NULL(efile
))
3900 static u64
cgroup_clone_children_read(struct cgroup
*cgrp
,
3903 return test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
3906 static int cgroup_clone_children_write(struct cgroup
*cgrp
,
3911 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
3913 clear_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
3918 * for the common functions, 'private' gives the type of file
3920 /* for hysterical raisins, we can't put this on the older files */
3921 #define CGROUP_FILE_GENERIC_PREFIX "cgroup."
3922 static struct cftype files
[] = {
3925 .open
= cgroup_tasks_open
,
3926 .write_u64
= cgroup_tasks_write
,
3927 .release
= cgroup_pidlist_release
,
3928 .mode
= S_IRUGO
| S_IWUSR
,
3931 .name
= CGROUP_FILE_GENERIC_PREFIX
"procs",
3932 .open
= cgroup_procs_open
,
3933 .write_u64
= cgroup_procs_write
,
3934 .release
= cgroup_pidlist_release
,
3935 .mode
= S_IRUGO
| S_IWUSR
,
3938 .name
= "notify_on_release",
3939 .read_u64
= cgroup_read_notify_on_release
,
3940 .write_u64
= cgroup_write_notify_on_release
,
3943 .name
= CGROUP_FILE_GENERIC_PREFIX
"event_control",
3944 .write_string
= cgroup_write_event_control
,
3948 .name
= "cgroup.clone_children",
3949 .read_u64
= cgroup_clone_children_read
,
3950 .write_u64
= cgroup_clone_children_write
,
3953 .name
= "release_agent",
3954 .flags
= CFTYPE_ONLY_ON_ROOT
,
3955 .read_seq_string
= cgroup_release_agent_show
,
3956 .write_string
= cgroup_release_agent_write
,
3957 .max_write_len
= PATH_MAX
,
3963 * cgroup_populate_dir - selectively creation of files in a directory
3964 * @cgrp: target cgroup
3965 * @base_files: true if the base files should be added
3966 * @subsys_mask: mask of the subsystem ids whose files should be added
3968 static int cgroup_populate_dir(struct cgroup
*cgrp
, bool base_files
,
3969 unsigned long subsys_mask
)
3972 struct cgroup_subsys
*ss
;
3975 err
= cgroup_addrm_files(cgrp
, NULL
, files
, true);
3980 /* process cftsets of each subsystem */
3981 for_each_subsys(cgrp
->root
, ss
) {
3982 struct cftype_set
*set
;
3983 if (!test_bit(ss
->subsys_id
, &subsys_mask
))
3986 list_for_each_entry(set
, &ss
->cftsets
, node
)
3987 cgroup_addrm_files(cgrp
, ss
, set
->cfts
, true);
3990 /* This cgroup is ready now */
3991 for_each_subsys(cgrp
->root
, ss
) {
3992 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
3994 * Update id->css pointer and make this css visible from
3995 * CSS ID functions. This pointer will be dereferened
3996 * from RCU-read-side without locks.
3999 rcu_assign_pointer(css
->id
->css
, css
);
4005 static void css_dput_fn(struct work_struct
*work
)
4007 struct cgroup_subsys_state
*css
=
4008 container_of(work
, struct cgroup_subsys_state
, dput_work
);
4009 struct dentry
*dentry
= css
->cgroup
->dentry
;
4010 struct super_block
*sb
= dentry
->d_sb
;
4012 atomic_inc(&sb
->s_active
);
4014 deactivate_super(sb
);
4017 static void init_cgroup_css(struct cgroup_subsys_state
*css
,
4018 struct cgroup_subsys
*ss
,
4019 struct cgroup
*cgrp
)
4022 atomic_set(&css
->refcnt
, 1);
4025 if (cgrp
== dummytop
)
4026 css
->flags
|= CSS_ROOT
;
4027 BUG_ON(cgrp
->subsys
[ss
->subsys_id
]);
4028 cgrp
->subsys
[ss
->subsys_id
] = css
;
4031 * css holds an extra ref to @cgrp->dentry which is put on the last
4032 * css_put(). dput() requires process context, which css_put() may
4033 * be called without. @css->dput_work will be used to invoke
4034 * dput() asynchronously from css_put().
4036 INIT_WORK(&css
->dput_work
, css_dput_fn
);
4039 /* invoke ->post_create() on a new CSS and mark it online if successful */
4040 static int online_css(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4044 lockdep_assert_held(&cgroup_mutex
);
4047 ret
= ss
->css_online(cgrp
);
4049 cgrp
->subsys
[ss
->subsys_id
]->flags
|= CSS_ONLINE
;
4053 /* if the CSS is online, invoke ->pre_destory() on it and mark it offline */
4054 static void offline_css(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4055 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
4057 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4059 lockdep_assert_held(&cgroup_mutex
);
4061 if (!(css
->flags
& CSS_ONLINE
))
4065 * css_offline() should be called with cgroup_mutex unlocked. See
4066 * 3fa59dfbc3 ("cgroup: fix potential deadlock in pre_destroy") for
4067 * details. This temporary unlocking should go away once
4068 * cgroup_mutex is unexported from controllers.
4070 if (ss
->css_offline
) {
4071 mutex_unlock(&cgroup_mutex
);
4072 ss
->css_offline(cgrp
);
4073 mutex_lock(&cgroup_mutex
);
4076 cgrp
->subsys
[ss
->subsys_id
]->flags
&= ~CSS_ONLINE
;
4080 * cgroup_create - create a cgroup
4081 * @parent: cgroup that will be parent of the new cgroup
4082 * @dentry: dentry of the new cgroup
4083 * @mode: mode to set on new inode
4085 * Must be called with the mutex on the parent inode held
4087 static long cgroup_create(struct cgroup
*parent
, struct dentry
*dentry
,
4090 struct cgroup
*cgrp
;
4091 struct cgroupfs_root
*root
= parent
->root
;
4093 struct cgroup_subsys
*ss
;
4094 struct super_block
*sb
= root
->sb
;
4096 cgrp
= kzalloc(sizeof(*cgrp
), GFP_KERNEL
);
4101 * Only live parents can have children. Note that the liveliness
4102 * check isn't strictly necessary because cgroup_mkdir() and
4103 * cgroup_rmdir() are fully synchronized by i_mutex; however, do it
4104 * anyway so that locking is contained inside cgroup proper and we
4105 * don't get nasty surprises if we ever grow another caller.
4107 if (!cgroup_lock_live_group(parent
)) {
4112 /* Grab a reference on the superblock so the hierarchy doesn't
4113 * get deleted on unmount if there are child cgroups. This
4114 * can be done outside cgroup_mutex, since the sb can't
4115 * disappear while someone has an open control file on the
4117 atomic_inc(&sb
->s_active
);
4119 init_cgroup_housekeeping(cgrp
);
4121 cgrp
->parent
= parent
;
4122 cgrp
->root
= parent
->root
;
4123 cgrp
->top_cgroup
= parent
->top_cgroup
;
4125 if (notify_on_release(parent
))
4126 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
4128 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
))
4129 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
4131 for_each_subsys(root
, ss
) {
4132 struct cgroup_subsys_state
*css
;
4134 css
= ss
->css_alloc(cgrp
);
4139 init_cgroup_css(css
, ss
, cgrp
);
4141 err
= alloc_css_id(ss
, parent
, cgrp
);
4145 /* At error, ->css_free() callback has to free assigned ID. */
4146 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
) &&
4148 ss
->post_clone(cgrp
);
4150 if (ss
->broken_hierarchy
&& !ss
->warned_broken_hierarchy
&&
4152 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",
4153 current
->comm
, current
->pid
, ss
->name
);
4154 if (!strcmp(ss
->name
, "memory"))
4155 pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
4156 ss
->warned_broken_hierarchy
= true;
4161 * Create directory. cgroup_create_file() returns with the new
4162 * directory locked on success so that it can be populated without
4163 * dropping cgroup_mutex.
4165 err
= cgroup_create_file(dentry
, S_IFDIR
| mode
, sb
);
4168 lockdep_assert_held(&dentry
->d_inode
->i_mutex
);
4170 /* allocation complete, commit to creation */
4171 dentry
->d_fsdata
= cgrp
;
4172 cgrp
->dentry
= dentry
;
4173 list_add_tail(&cgrp
->allcg_node
, &root
->allcg_list
);
4174 list_add_tail_rcu(&cgrp
->sibling
, &cgrp
->parent
->children
);
4175 root
->number_of_cgroups
++;
4177 /* each css holds a ref to the cgroup's dentry */
4178 for_each_subsys(root
, ss
)
4181 /* creation succeeded, notify subsystems */
4182 for_each_subsys(root
, ss
) {
4183 err
= online_css(ss
, cgrp
);
4188 err
= cgroup_populate_dir(cgrp
, true, root
->subsys_mask
);
4192 mutex_unlock(&cgroup_mutex
);
4193 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
4198 for_each_subsys(root
, ss
) {
4199 if (cgrp
->subsys
[ss
->subsys_id
])
4202 mutex_unlock(&cgroup_mutex
);
4203 /* Release the reference count that we took on the superblock */
4204 deactivate_super(sb
);
4210 cgroup_destroy_locked(cgrp
);
4211 mutex_unlock(&cgroup_mutex
);
4212 mutex_unlock(&dentry
->d_inode
->i_mutex
);
4216 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
4218 struct cgroup
*c_parent
= dentry
->d_parent
->d_fsdata
;
4220 /* the vfs holds inode->i_mutex already */
4221 return cgroup_create(c_parent
, dentry
, mode
| S_IFDIR
);
4225 * Check the reference count on each subsystem. Since we already
4226 * established that there are no tasks in the cgroup, if the css refcount
4227 * is also 1, then there should be no outstanding references, so the
4228 * subsystem is safe to destroy. We scan across all subsystems rather than
4229 * using the per-hierarchy linked list of mounted subsystems since we can
4230 * be called via check_for_release() with no synchronization other than
4231 * RCU, and the subsystem linked list isn't RCU-safe.
4233 static int cgroup_has_css_refs(struct cgroup
*cgrp
)
4238 * We won't need to lock the subsys array, because the subsystems
4239 * we're concerned about aren't going anywhere since our cgroup root
4240 * has a reference on them.
4242 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4243 struct cgroup_subsys
*ss
= subsys
[i
];
4244 struct cgroup_subsys_state
*css
;
4246 /* Skip subsystems not present or not in this hierarchy */
4247 if (ss
== NULL
|| ss
->root
!= cgrp
->root
)
4250 css
= cgrp
->subsys
[ss
->subsys_id
];
4252 * When called from check_for_release() it's possible
4253 * that by this point the cgroup has been removed
4254 * and the css deleted. But a false-positive doesn't
4255 * matter, since it can only happen if the cgroup
4256 * has been deleted and hence no longer needs the
4257 * release agent to be called anyway.
4259 if (css
&& css_refcnt(css
) > 1)
4265 static int cgroup_destroy_locked(struct cgroup
*cgrp
)
4266 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
4268 struct dentry
*d
= cgrp
->dentry
;
4269 struct cgroup
*parent
= cgrp
->parent
;
4271 struct cgroup_event
*event
, *tmp
;
4272 struct cgroup_subsys
*ss
;
4274 lockdep_assert_held(&d
->d_inode
->i_mutex
);
4275 lockdep_assert_held(&cgroup_mutex
);
4277 if (atomic_read(&cgrp
->count
) || !list_empty(&cgrp
->children
))
4281 * Block new css_tryget() by deactivating refcnt and mark @cgrp
4282 * removed. This makes future css_tryget() and child creation
4283 * attempts fail thus maintaining the removal conditions verified
4286 for_each_subsys(cgrp
->root
, ss
) {
4287 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4289 WARN_ON(atomic_read(&css
->refcnt
) < 0);
4290 atomic_add(CSS_DEACT_BIAS
, &css
->refcnt
);
4292 set_bit(CGRP_REMOVED
, &cgrp
->flags
);
4294 /* tell subsystems to initate destruction */
4295 for_each_subsys(cgrp
->root
, ss
)
4296 offline_css(ss
, cgrp
);
4299 * Put all the base refs. Each css holds an extra reference to the
4300 * cgroup's dentry and cgroup removal proceeds regardless of css
4301 * refs. On the last put of each css, whenever that may be, the
4302 * extra dentry ref is put so that dentry destruction happens only
4303 * after all css's are released.
4305 for_each_subsys(cgrp
->root
, ss
)
4306 css_put(cgrp
->subsys
[ss
->subsys_id
]);
4308 raw_spin_lock(&release_list_lock
);
4309 if (!list_empty(&cgrp
->release_list
))
4310 list_del_init(&cgrp
->release_list
);
4311 raw_spin_unlock(&release_list_lock
);
4313 /* delete this cgroup from parent->children */
4314 list_del_rcu(&cgrp
->sibling
);
4315 list_del_init(&cgrp
->allcg_node
);
4318 cgroup_d_remove_dir(d
);
4321 set_bit(CGRP_RELEASABLE
, &parent
->flags
);
4322 check_for_release(parent
);
4325 * Unregister events and notify userspace.
4326 * Notify userspace about cgroup removing only after rmdir of cgroup
4327 * directory to avoid race between userspace and kernelspace
4329 spin_lock(&cgrp
->event_list_lock
);
4330 list_for_each_entry_safe(event
, tmp
, &cgrp
->event_list
, list
) {
4331 list_del(&event
->list
);
4332 remove_wait_queue(event
->wqh
, &event
->wait
);
4333 eventfd_signal(event
->eventfd
, 1);
4334 schedule_work(&event
->remove
);
4336 spin_unlock(&cgrp
->event_list_lock
);
4341 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
)
4345 mutex_lock(&cgroup_mutex
);
4346 ret
= cgroup_destroy_locked(dentry
->d_fsdata
);
4347 mutex_unlock(&cgroup_mutex
);
4352 static void __init_or_module
cgroup_init_cftsets(struct cgroup_subsys
*ss
)
4354 INIT_LIST_HEAD(&ss
->cftsets
);
4357 * base_cftset is embedded in subsys itself, no need to worry about
4360 if (ss
->base_cftypes
) {
4361 ss
->base_cftset
.cfts
= ss
->base_cftypes
;
4362 list_add_tail(&ss
->base_cftset
.node
, &ss
->cftsets
);
4366 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
)
4368 struct cgroup_subsys_state
*css
;
4370 printk(KERN_INFO
"Initializing cgroup subsys %s\n", ss
->name
);
4372 mutex_lock(&cgroup_mutex
);
4374 /* init base cftset */
4375 cgroup_init_cftsets(ss
);
4377 /* Create the top cgroup state for this subsystem */
4378 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
4379 ss
->root
= &rootnode
;
4380 css
= ss
->css_alloc(dummytop
);
4381 /* We don't handle early failures gracefully */
4382 BUG_ON(IS_ERR(css
));
4383 init_cgroup_css(css
, ss
, dummytop
);
4385 /* Update the init_css_set to contain a subsys
4386 * pointer to this state - since the subsystem is
4387 * newly registered, all tasks and hence the
4388 * init_css_set is in the subsystem's top cgroup. */
4389 init_css_set
.subsys
[ss
->subsys_id
] = css
;
4391 need_forkexit_callback
|= ss
->fork
|| ss
->exit
;
4393 /* At system boot, before all subsystems have been
4394 * registered, no tasks have been forked, so we don't
4395 * need to invoke fork callbacks here. */
4396 BUG_ON(!list_empty(&init_task
.tasks
));
4399 BUG_ON(online_css(ss
, dummytop
));
4401 mutex_unlock(&cgroup_mutex
);
4403 /* this function shouldn't be used with modular subsystems, since they
4404 * need to register a subsys_id, among other things */
4409 * cgroup_load_subsys: load and register a modular subsystem at runtime
4410 * @ss: the subsystem to load
4412 * This function should be called in a modular subsystem's initcall. If the
4413 * subsystem is built as a module, it will be assigned a new subsys_id and set
4414 * up for use. If the subsystem is built-in anyway, work is delegated to the
4415 * simpler cgroup_init_subsys.
4417 int __init_or_module
cgroup_load_subsys(struct cgroup_subsys
*ss
)
4419 struct cgroup_subsys_state
*css
;
4422 /* check name and function validity */
4423 if (ss
->name
== NULL
|| strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
||
4424 ss
->css_alloc
== NULL
|| ss
->css_free
== NULL
)
4428 * we don't support callbacks in modular subsystems. this check is
4429 * before the ss->module check for consistency; a subsystem that could
4430 * be a module should still have no callbacks even if the user isn't
4431 * compiling it as one.
4433 if (ss
->fork
|| ss
->exit
)
4437 * an optionally modular subsystem is built-in: we want to do nothing,
4438 * since cgroup_init_subsys will have already taken care of it.
4440 if (ss
->module
== NULL
) {
4441 /* a sanity check */
4442 BUG_ON(subsys
[ss
->subsys_id
] != ss
);
4446 /* init base cftset */
4447 cgroup_init_cftsets(ss
);
4449 mutex_lock(&cgroup_mutex
);
4450 subsys
[ss
->subsys_id
] = ss
;
4453 * no ss->css_alloc seems to need anything important in the ss
4454 * struct, so this can happen first (i.e. before the rootnode
4457 css
= ss
->css_alloc(dummytop
);
4459 /* failure case - need to deassign the subsys[] slot. */
4460 subsys
[ss
->subsys_id
] = NULL
;
4461 mutex_unlock(&cgroup_mutex
);
4462 return PTR_ERR(css
);
4465 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
4466 ss
->root
= &rootnode
;
4468 /* our new subsystem will be attached to the dummy hierarchy. */
4469 init_cgroup_css(css
, ss
, dummytop
);
4470 /* init_idr must be after init_cgroup_css because it sets css->id. */
4472 ret
= cgroup_init_idr(ss
, css
);
4478 * Now we need to entangle the css into the existing css_sets. unlike
4479 * in cgroup_init_subsys, there are now multiple css_sets, so each one
4480 * will need a new pointer to it; done by iterating the css_set_table.
4481 * furthermore, modifying the existing css_sets will corrupt the hash
4482 * table state, so each changed css_set will need its hash recomputed.
4483 * this is all done under the css_set_lock.
4485 write_lock(&css_set_lock
);
4486 for (i
= 0; i
< CSS_SET_TABLE_SIZE
; i
++) {
4488 struct hlist_node
*node
, *tmp
;
4489 struct hlist_head
*bucket
= &css_set_table
[i
], *new_bucket
;
4491 hlist_for_each_entry_safe(cg
, node
, tmp
, bucket
, hlist
) {
4492 /* skip entries that we already rehashed */
4493 if (cg
->subsys
[ss
->subsys_id
])
4495 /* remove existing entry */
4496 hlist_del(&cg
->hlist
);
4498 cg
->subsys
[ss
->subsys_id
] = css
;
4499 /* recompute hash and restore entry */
4500 new_bucket
= css_set_hash(cg
->subsys
);
4501 hlist_add_head(&cg
->hlist
, new_bucket
);
4504 write_unlock(&css_set_lock
);
4507 ret
= online_css(ss
, dummytop
);
4512 mutex_unlock(&cgroup_mutex
);
4516 mutex_unlock(&cgroup_mutex
);
4517 /* @ss can't be mounted here as try_module_get() would fail */
4518 cgroup_unload_subsys(ss
);
4521 EXPORT_SYMBOL_GPL(cgroup_load_subsys
);
4524 * cgroup_unload_subsys: unload a modular subsystem
4525 * @ss: the subsystem to unload
4527 * This function should be called in a modular subsystem's exitcall. When this
4528 * function is invoked, the refcount on the subsystem's module will be 0, so
4529 * the subsystem will not be attached to any hierarchy.
4531 void cgroup_unload_subsys(struct cgroup_subsys
*ss
)
4533 struct cg_cgroup_link
*link
;
4534 struct hlist_head
*hhead
;
4536 BUG_ON(ss
->module
== NULL
);
4539 * we shouldn't be called if the subsystem is in use, and the use of
4540 * try_module_get in parse_cgroupfs_options should ensure that it
4541 * doesn't start being used while we're killing it off.
4543 BUG_ON(ss
->root
!= &rootnode
);
4545 mutex_lock(&cgroup_mutex
);
4547 offline_css(ss
, dummytop
);
4551 idr_remove_all(&ss
->idr
);
4552 idr_destroy(&ss
->idr
);
4555 /* deassign the subsys_id */
4556 subsys
[ss
->subsys_id
] = NULL
;
4558 /* remove subsystem from rootnode's list of subsystems */
4559 list_del_init(&ss
->sibling
);
4562 * disentangle the css from all css_sets attached to the dummytop. as
4563 * in loading, we need to pay our respects to the hashtable gods.
4565 write_lock(&css_set_lock
);
4566 list_for_each_entry(link
, &dummytop
->css_sets
, cgrp_link_list
) {
4567 struct css_set
*cg
= link
->cg
;
4569 hlist_del(&cg
->hlist
);
4570 cg
->subsys
[ss
->subsys_id
] = NULL
;
4571 hhead
= css_set_hash(cg
->subsys
);
4572 hlist_add_head(&cg
->hlist
, hhead
);
4574 write_unlock(&css_set_lock
);
4577 * remove subsystem's css from the dummytop and free it - need to
4578 * free before marking as null because ss->css_free needs the
4579 * cgrp->subsys pointer to find their state. note that this also
4580 * takes care of freeing the css_id.
4582 ss
->css_free(dummytop
);
4583 dummytop
->subsys
[ss
->subsys_id
] = NULL
;
4585 mutex_unlock(&cgroup_mutex
);
4587 EXPORT_SYMBOL_GPL(cgroup_unload_subsys
);
4590 * cgroup_init_early - cgroup initialization at system boot
4592 * Initialize cgroups at system boot, and initialize any
4593 * subsystems that request early init.
4595 int __init
cgroup_init_early(void)
4598 atomic_set(&init_css_set
.refcount
, 1);
4599 INIT_LIST_HEAD(&init_css_set
.cg_links
);
4600 INIT_LIST_HEAD(&init_css_set
.tasks
);
4601 INIT_HLIST_NODE(&init_css_set
.hlist
);
4603 init_cgroup_root(&rootnode
);
4605 init_task
.cgroups
= &init_css_set
;
4607 init_css_set_link
.cg
= &init_css_set
;
4608 init_css_set_link
.cgrp
= dummytop
;
4609 list_add(&init_css_set_link
.cgrp_link_list
,
4610 &rootnode
.top_cgroup
.css_sets
);
4611 list_add(&init_css_set_link
.cg_link_list
,
4612 &init_css_set
.cg_links
);
4614 for (i
= 0; i
< CSS_SET_TABLE_SIZE
; i
++)
4615 INIT_HLIST_HEAD(&css_set_table
[i
]);
4617 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4618 struct cgroup_subsys
*ss
= subsys
[i
];
4620 /* at bootup time, we don't worry about modular subsystems */
4621 if (!ss
|| ss
->module
)
4625 BUG_ON(strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
);
4626 BUG_ON(!ss
->css_alloc
);
4627 BUG_ON(!ss
->css_free
);
4628 if (ss
->subsys_id
!= i
) {
4629 printk(KERN_ERR
"cgroup: Subsys %s id == %d\n",
4630 ss
->name
, ss
->subsys_id
);
4635 cgroup_init_subsys(ss
);
4641 * cgroup_init - cgroup initialization
4643 * Register cgroup filesystem and /proc file, and initialize
4644 * any subsystems that didn't request early init.
4646 int __init
cgroup_init(void)
4650 struct hlist_head
*hhead
;
4652 err
= bdi_init(&cgroup_backing_dev_info
);
4656 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4657 struct cgroup_subsys
*ss
= subsys
[i
];
4659 /* at bootup time, we don't worry about modular subsystems */
4660 if (!ss
|| ss
->module
)
4662 if (!ss
->early_init
)
4663 cgroup_init_subsys(ss
);
4665 cgroup_init_idr(ss
, init_css_set
.subsys
[ss
->subsys_id
]);
4668 /* Add init_css_set to the hash table */
4669 hhead
= css_set_hash(init_css_set
.subsys
);
4670 hlist_add_head(&init_css_set
.hlist
, hhead
);
4671 BUG_ON(!init_root_id(&rootnode
));
4673 cgroup_kobj
= kobject_create_and_add("cgroup", fs_kobj
);
4679 err
= register_filesystem(&cgroup_fs_type
);
4681 kobject_put(cgroup_kobj
);
4685 proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
);
4689 bdi_destroy(&cgroup_backing_dev_info
);
4695 * proc_cgroup_show()
4696 * - Print task's cgroup paths into seq_file, one line for each hierarchy
4697 * - Used for /proc/<pid>/cgroup.
4698 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
4699 * doesn't really matter if tsk->cgroup changes after we read it,
4700 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
4701 * anyway. No need to check that tsk->cgroup != NULL, thanks to
4702 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
4703 * cgroup to top_cgroup.
4706 /* TODO: Use a proper seq_file iterator */
4707 static int proc_cgroup_show(struct seq_file
*m
, void *v
)
4710 struct task_struct
*tsk
;
4713 struct cgroupfs_root
*root
;
4716 buf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
4722 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
4728 mutex_lock(&cgroup_mutex
);
4730 for_each_active_root(root
) {
4731 struct cgroup_subsys
*ss
;
4732 struct cgroup
*cgrp
;
4735 seq_printf(m
, "%d:", root
->hierarchy_id
);
4736 for_each_subsys(root
, ss
)
4737 seq_printf(m
, "%s%s", count
++ ? "," : "", ss
->name
);
4738 if (strlen(root
->name
))
4739 seq_printf(m
, "%sname=%s", count
? "," : "",
4742 cgrp
= task_cgroup_from_root(tsk
, root
);
4743 retval
= cgroup_path(cgrp
, buf
, PAGE_SIZE
);
4751 mutex_unlock(&cgroup_mutex
);
4752 put_task_struct(tsk
);
4759 static int cgroup_open(struct inode
*inode
, struct file
*file
)
4761 struct pid
*pid
= PROC_I(inode
)->pid
;
4762 return single_open(file
, proc_cgroup_show
, pid
);
4765 const struct file_operations proc_cgroup_operations
= {
4766 .open
= cgroup_open
,
4768 .llseek
= seq_lseek
,
4769 .release
= single_release
,
4772 /* Display information about each subsystem and each hierarchy */
4773 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
4777 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
4779 * ideally we don't want subsystems moving around while we do this.
4780 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
4781 * subsys/hierarchy state.
4783 mutex_lock(&cgroup_mutex
);
4784 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4785 struct cgroup_subsys
*ss
= subsys
[i
];
4788 seq_printf(m
, "%s\t%d\t%d\t%d\n",
4789 ss
->name
, ss
->root
->hierarchy_id
,
4790 ss
->root
->number_of_cgroups
, !ss
->disabled
);
4792 mutex_unlock(&cgroup_mutex
);
4796 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
4798 return single_open(file
, proc_cgroupstats_show
, NULL
);
4801 static const struct file_operations proc_cgroupstats_operations
= {
4802 .open
= cgroupstats_open
,
4804 .llseek
= seq_lseek
,
4805 .release
= single_release
,
4809 * cgroup_fork - attach newly forked task to its parents cgroup.
4810 * @child: pointer to task_struct of forking parent process.
4812 * Description: A task inherits its parent's cgroup at fork().
4814 * A pointer to the shared css_set was automatically copied in
4815 * fork.c by dup_task_struct(). However, we ignore that copy, since
4816 * it was not made under the protection of RCU or cgroup_mutex, so
4817 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
4818 * have already changed current->cgroups, allowing the previously
4819 * referenced cgroup group to be removed and freed.
4821 * At the point that cgroup_fork() is called, 'current' is the parent
4822 * task, and the passed argument 'child' points to the child task.
4824 void cgroup_fork(struct task_struct
*child
)
4827 child
->cgroups
= current
->cgroups
;
4828 get_css_set(child
->cgroups
);
4829 task_unlock(current
);
4830 INIT_LIST_HEAD(&child
->cg_list
);
4834 * cgroup_post_fork - called on a new task after adding it to the task list
4835 * @child: the task in question
4837 * Adds the task to the list running through its css_set if necessary and
4838 * call the subsystem fork() callbacks. Has to be after the task is
4839 * visible on the task list in case we race with the first call to
4840 * cgroup_iter_start() - to guarantee that the new task ends up on its
4843 void cgroup_post_fork(struct task_struct
*child
)
4848 * use_task_css_set_links is set to 1 before we walk the tasklist
4849 * under the tasklist_lock and we read it here after we added the child
4850 * to the tasklist under the tasklist_lock as well. If the child wasn't
4851 * yet in the tasklist when we walked through it from
4852 * cgroup_enable_task_cg_lists(), then use_task_css_set_links value
4853 * should be visible now due to the paired locking and barriers implied
4854 * by LOCK/UNLOCK: it is written before the tasklist_lock unlock
4855 * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
4858 if (use_task_css_set_links
) {
4859 write_lock(&css_set_lock
);
4861 if (list_empty(&child
->cg_list
))
4862 list_add(&child
->cg_list
, &child
->cgroups
->tasks
);
4864 write_unlock(&css_set_lock
);
4868 * Call ss->fork(). This must happen after @child is linked on
4869 * css_set; otherwise, @child might change state between ->fork()
4870 * and addition to css_set.
4872 if (need_forkexit_callback
) {
4873 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4874 struct cgroup_subsys
*ss
= subsys
[i
];
4877 * fork/exit callbacks are supported only for
4878 * builtin subsystems and we don't need further
4879 * synchronization as they never go away.
4881 if (!ss
|| ss
->module
)
4891 * cgroup_exit - detach cgroup from exiting task
4892 * @tsk: pointer to task_struct of exiting process
4893 * @run_callback: run exit callbacks?
4895 * Description: Detach cgroup from @tsk and release it.
4897 * Note that cgroups marked notify_on_release force every task in
4898 * them to take the global cgroup_mutex mutex when exiting.
4899 * This could impact scaling on very large systems. Be reluctant to
4900 * use notify_on_release cgroups where very high task exit scaling
4901 * is required on large systems.
4903 * the_top_cgroup_hack:
4905 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
4907 * We call cgroup_exit() while the task is still competent to
4908 * handle notify_on_release(), then leave the task attached to the
4909 * root cgroup in each hierarchy for the remainder of its exit.
4911 * To do this properly, we would increment the reference count on
4912 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
4913 * code we would add a second cgroup function call, to drop that
4914 * reference. This would just create an unnecessary hot spot on
4915 * the top_cgroup reference count, to no avail.
4917 * Normally, holding a reference to a cgroup without bumping its
4918 * count is unsafe. The cgroup could go away, or someone could
4919 * attach us to a different cgroup, decrementing the count on
4920 * the first cgroup that we never incremented. But in this case,
4921 * top_cgroup isn't going away, and either task has PF_EXITING set,
4922 * which wards off any cgroup_attach_task() attempts, or task is a failed
4923 * fork, never visible to cgroup_attach_task.
4925 void cgroup_exit(struct task_struct
*tsk
, int run_callbacks
)
4931 * Unlink from the css_set task list if necessary.
4932 * Optimistically check cg_list before taking
4935 if (!list_empty(&tsk
->cg_list
)) {
4936 write_lock(&css_set_lock
);
4937 if (!list_empty(&tsk
->cg_list
))
4938 list_del_init(&tsk
->cg_list
);
4939 write_unlock(&css_set_lock
);
4942 /* Reassign the task to the init_css_set. */
4945 tsk
->cgroups
= &init_css_set
;
4947 if (run_callbacks
&& need_forkexit_callback
) {
4948 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4949 struct cgroup_subsys
*ss
= subsys
[i
];
4951 /* modular subsystems can't use callbacks */
4952 if (!ss
|| ss
->module
)
4956 struct cgroup
*old_cgrp
=
4957 rcu_dereference_raw(cg
->subsys
[i
])->cgroup
;
4958 struct cgroup
*cgrp
= task_cgroup(tsk
, i
);
4959 ss
->exit(cgrp
, old_cgrp
, tsk
);
4966 put_css_set_taskexit(cg
);
4970 * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
4971 * @cgrp: the cgroup in question
4972 * @task: the task in question
4974 * See if @cgrp is a descendant of @task's cgroup in the appropriate
4977 * If we are sending in dummytop, then presumably we are creating
4978 * the top cgroup in the subsystem.
4980 * Called only by the ns (nsproxy) cgroup.
4982 int cgroup_is_descendant(const struct cgroup
*cgrp
, struct task_struct
*task
)
4985 struct cgroup
*target
;
4987 if (cgrp
== dummytop
)
4990 target
= task_cgroup_from_root(task
, cgrp
->root
);
4991 while (cgrp
!= target
&& cgrp
!= cgrp
->top_cgroup
)
4992 cgrp
= cgrp
->parent
;
4993 ret
= (cgrp
== target
);
4997 static void check_for_release(struct cgroup
*cgrp
)
4999 /* All of these checks rely on RCU to keep the cgroup
5000 * structure alive */
5001 if (cgroup_is_releasable(cgrp
) && !atomic_read(&cgrp
->count
)
5002 && list_empty(&cgrp
->children
) && !cgroup_has_css_refs(cgrp
)) {
5003 /* Control Group is currently removeable. If it's not
5004 * already queued for a userspace notification, queue
5006 int need_schedule_work
= 0;
5007 raw_spin_lock(&release_list_lock
);
5008 if (!cgroup_is_removed(cgrp
) &&
5009 list_empty(&cgrp
->release_list
)) {
5010 list_add(&cgrp
->release_list
, &release_list
);
5011 need_schedule_work
= 1;
5013 raw_spin_unlock(&release_list_lock
);
5014 if (need_schedule_work
)
5015 schedule_work(&release_agent_work
);
5019 /* Caller must verify that the css is not for root cgroup */
5020 bool __css_tryget(struct cgroup_subsys_state
*css
)
5025 v
= css_refcnt(css
);
5026 t
= atomic_cmpxchg(&css
->refcnt
, v
, v
+ 1);
5034 EXPORT_SYMBOL_GPL(__css_tryget
);
5036 /* Caller must verify that the css is not for root cgroup */
5037 void __css_put(struct cgroup_subsys_state
*css
)
5039 struct cgroup
*cgrp
= css
->cgroup
;
5043 v
= css_unbias_refcnt(atomic_dec_return(&css
->refcnt
));
5047 if (notify_on_release(cgrp
)) {
5048 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
5049 check_for_release(cgrp
);
5053 schedule_work(&css
->dput_work
);
5058 EXPORT_SYMBOL_GPL(__css_put
);
5061 * Notify userspace when a cgroup is released, by running the
5062 * configured release agent with the name of the cgroup (path
5063 * relative to the root of cgroup file system) as the argument.
5065 * Most likely, this user command will try to rmdir this cgroup.
5067 * This races with the possibility that some other task will be
5068 * attached to this cgroup before it is removed, or that some other
5069 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
5070 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
5071 * unused, and this cgroup will be reprieved from its death sentence,
5072 * to continue to serve a useful existence. Next time it's released,
5073 * we will get notified again, if it still has 'notify_on_release' set.
5075 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
5076 * means only wait until the task is successfully execve()'d. The
5077 * separate release agent task is forked by call_usermodehelper(),
5078 * then control in this thread returns here, without waiting for the
5079 * release agent task. We don't bother to wait because the caller of
5080 * this routine has no use for the exit status of the release agent
5081 * task, so no sense holding our caller up for that.
5083 static void cgroup_release_agent(struct work_struct
*work
)
5085 BUG_ON(work
!= &release_agent_work
);
5086 mutex_lock(&cgroup_mutex
);
5087 raw_spin_lock(&release_list_lock
);
5088 while (!list_empty(&release_list
)) {
5089 char *argv
[3], *envp
[3];
5091 char *pathbuf
= NULL
, *agentbuf
= NULL
;
5092 struct cgroup
*cgrp
= list_entry(release_list
.next
,
5095 list_del_init(&cgrp
->release_list
);
5096 raw_spin_unlock(&release_list_lock
);
5097 pathbuf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
5100 if (cgroup_path(cgrp
, pathbuf
, PAGE_SIZE
) < 0)
5102 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
5107 argv
[i
++] = agentbuf
;
5108 argv
[i
++] = pathbuf
;
5112 /* minimal command environment */
5113 envp
[i
++] = "HOME=/";
5114 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
5117 /* Drop the lock while we invoke the usermode helper,
5118 * since the exec could involve hitting disk and hence
5119 * be a slow process */
5120 mutex_unlock(&cgroup_mutex
);
5121 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
5122 mutex_lock(&cgroup_mutex
);
5126 raw_spin_lock(&release_list_lock
);
5128 raw_spin_unlock(&release_list_lock
);
5129 mutex_unlock(&cgroup_mutex
);
5132 static int __init
cgroup_disable(char *str
)
5137 while ((token
= strsep(&str
, ",")) != NULL
) {
5140 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
5141 struct cgroup_subsys
*ss
= subsys
[i
];
5144 * cgroup_disable, being at boot time, can't
5145 * know about module subsystems, so we don't
5148 if (!ss
|| ss
->module
)
5151 if (!strcmp(token
, ss
->name
)) {
5153 printk(KERN_INFO
"Disabling %s control group"
5154 " subsystem\n", ss
->name
);
5161 __setup("cgroup_disable=", cgroup_disable
);
5164 * Functons for CSS ID.
5168 *To get ID other than 0, this should be called when !cgroup_is_removed().
5170 unsigned short css_id(struct cgroup_subsys_state
*css
)
5172 struct css_id
*cssid
;
5175 * This css_id() can return correct value when somone has refcnt
5176 * on this or this is under rcu_read_lock(). Once css->id is allocated,
5177 * it's unchanged until freed.
5179 cssid
= rcu_dereference_check(css
->id
, css_refcnt(css
));
5185 EXPORT_SYMBOL_GPL(css_id
);
5187 unsigned short css_depth(struct cgroup_subsys_state
*css
)
5189 struct css_id
*cssid
;
5191 cssid
= rcu_dereference_check(css
->id
, css_refcnt(css
));
5194 return cssid
->depth
;
5197 EXPORT_SYMBOL_GPL(css_depth
);
5200 * css_is_ancestor - test "root" css is an ancestor of "child"
5201 * @child: the css to be tested.
5202 * @root: the css supporsed to be an ancestor of the child.
5204 * Returns true if "root" is an ancestor of "child" in its hierarchy. Because
5205 * this function reads css->id, the caller must hold rcu_read_lock().
5206 * But, considering usual usage, the csses should be valid objects after test.
5207 * Assuming that the caller will do some action to the child if this returns
5208 * returns true, the caller must take "child";s reference count.
5209 * If "child" is valid object and this returns true, "root" is valid, too.
5212 bool css_is_ancestor(struct cgroup_subsys_state
*child
,
5213 const struct cgroup_subsys_state
*root
)
5215 struct css_id
*child_id
;
5216 struct css_id
*root_id
;
5218 child_id
= rcu_dereference(child
->id
);
5221 root_id
= rcu_dereference(root
->id
);
5224 if (child_id
->depth
< root_id
->depth
)
5226 if (child_id
->stack
[root_id
->depth
] != root_id
->id
)
5231 void free_css_id(struct cgroup_subsys
*ss
, struct cgroup_subsys_state
*css
)
5233 struct css_id
*id
= css
->id
;
5234 /* When this is called before css_id initialization, id can be NULL */
5238 BUG_ON(!ss
->use_id
);
5240 rcu_assign_pointer(id
->css
, NULL
);
5241 rcu_assign_pointer(css
->id
, NULL
);
5242 spin_lock(&ss
->id_lock
);
5243 idr_remove(&ss
->idr
, id
->id
);
5244 spin_unlock(&ss
->id_lock
);
5245 kfree_rcu(id
, rcu_head
);
5247 EXPORT_SYMBOL_GPL(free_css_id
);
5250 * This is called by init or create(). Then, calls to this function are
5251 * always serialized (By cgroup_mutex() at create()).
5254 static struct css_id
*get_new_cssid(struct cgroup_subsys
*ss
, int depth
)
5256 struct css_id
*newid
;
5257 int myid
, error
, size
;
5259 BUG_ON(!ss
->use_id
);
5261 size
= sizeof(*newid
) + sizeof(unsigned short) * (depth
+ 1);
5262 newid
= kzalloc(size
, GFP_KERNEL
);
5264 return ERR_PTR(-ENOMEM
);
5266 if (unlikely(!idr_pre_get(&ss
->idr
, GFP_KERNEL
))) {
5270 spin_lock(&ss
->id_lock
);
5271 /* Don't use 0. allocates an ID of 1-65535 */
5272 error
= idr_get_new_above(&ss
->idr
, newid
, 1, &myid
);
5273 spin_unlock(&ss
->id_lock
);
5275 /* Returns error when there are no free spaces for new ID.*/
5280 if (myid
> CSS_ID_MAX
)
5284 newid
->depth
= depth
;
5288 spin_lock(&ss
->id_lock
);
5289 idr_remove(&ss
->idr
, myid
);
5290 spin_unlock(&ss
->id_lock
);
5293 return ERR_PTR(error
);
5297 static int __init_or_module
cgroup_init_idr(struct cgroup_subsys
*ss
,
5298 struct cgroup_subsys_state
*rootcss
)
5300 struct css_id
*newid
;
5302 spin_lock_init(&ss
->id_lock
);
5305 newid
= get_new_cssid(ss
, 0);
5307 return PTR_ERR(newid
);
5309 newid
->stack
[0] = newid
->id
;
5310 newid
->css
= rootcss
;
5311 rootcss
->id
= newid
;
5315 static int alloc_css_id(struct cgroup_subsys
*ss
, struct cgroup
*parent
,
5316 struct cgroup
*child
)
5318 int subsys_id
, i
, depth
= 0;
5319 struct cgroup_subsys_state
*parent_css
, *child_css
;
5320 struct css_id
*child_id
, *parent_id
;
5322 subsys_id
= ss
->subsys_id
;
5323 parent_css
= parent
->subsys
[subsys_id
];
5324 child_css
= child
->subsys
[subsys_id
];
5325 parent_id
= parent_css
->id
;
5326 depth
= parent_id
->depth
+ 1;
5328 child_id
= get_new_cssid(ss
, depth
);
5329 if (IS_ERR(child_id
))
5330 return PTR_ERR(child_id
);
5332 for (i
= 0; i
< depth
; i
++)
5333 child_id
->stack
[i
] = parent_id
->stack
[i
];
5334 child_id
->stack
[depth
] = child_id
->id
;
5336 * child_id->css pointer will be set after this cgroup is available
5337 * see cgroup_populate_dir()
5339 rcu_assign_pointer(child_css
->id
, child_id
);
5345 * css_lookup - lookup css by id
5346 * @ss: cgroup subsys to be looked into.
5349 * Returns pointer to cgroup_subsys_state if there is valid one with id.
5350 * NULL if not. Should be called under rcu_read_lock()
5352 struct cgroup_subsys_state
*css_lookup(struct cgroup_subsys
*ss
, int id
)
5354 struct css_id
*cssid
= NULL
;
5356 BUG_ON(!ss
->use_id
);
5357 cssid
= idr_find(&ss
->idr
, id
);
5359 if (unlikely(!cssid
))
5362 return rcu_dereference(cssid
->css
);
5364 EXPORT_SYMBOL_GPL(css_lookup
);
5367 * css_get_next - lookup next cgroup under specified hierarchy.
5368 * @ss: pointer to subsystem
5369 * @id: current position of iteration.
5370 * @root: pointer to css. search tree under this.
5371 * @foundid: position of found object.
5373 * Search next css under the specified hierarchy of rootid. Calling under
5374 * rcu_read_lock() is necessary. Returns NULL if it reaches the end.
5376 struct cgroup_subsys_state
*
5377 css_get_next(struct cgroup_subsys
*ss
, int id
,
5378 struct cgroup_subsys_state
*root
, int *foundid
)
5380 struct cgroup_subsys_state
*ret
= NULL
;
5383 int rootid
= css_id(root
);
5384 int depth
= css_depth(root
);
5389 BUG_ON(!ss
->use_id
);
5390 WARN_ON_ONCE(!rcu_read_lock_held());
5392 /* fill start point for scan */
5396 * scan next entry from bitmap(tree), tmpid is updated after
5399 tmp
= idr_get_next(&ss
->idr
, &tmpid
);
5402 if (tmp
->depth
>= depth
&& tmp
->stack
[depth
] == rootid
) {
5403 ret
= rcu_dereference(tmp
->css
);
5409 /* continue to scan from next id */
5416 * get corresponding css from file open on cgroupfs directory
5418 struct cgroup_subsys_state
*cgroup_css_from_dir(struct file
*f
, int id
)
5420 struct cgroup
*cgrp
;
5421 struct inode
*inode
;
5422 struct cgroup_subsys_state
*css
;
5424 inode
= f
->f_dentry
->d_inode
;
5425 /* check in cgroup filesystem dir */
5426 if (inode
->i_op
!= &cgroup_dir_inode_operations
)
5427 return ERR_PTR(-EBADF
);
5429 if (id
< 0 || id
>= CGROUP_SUBSYS_COUNT
)
5430 return ERR_PTR(-EINVAL
);
5433 cgrp
= __d_cgrp(f
->f_dentry
);
5434 css
= cgrp
->subsys
[id
];
5435 return css
? css
: ERR_PTR(-ENOENT
);
5438 #ifdef CONFIG_CGROUP_DEBUG
5439 static struct cgroup_subsys_state
*debug_css_alloc(struct cgroup
*cont
)
5441 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
5444 return ERR_PTR(-ENOMEM
);
5449 static void debug_css_free(struct cgroup
*cont
)
5451 kfree(cont
->subsys
[debug_subsys_id
]);
5454 static u64
cgroup_refcount_read(struct cgroup
*cont
, struct cftype
*cft
)
5456 return atomic_read(&cont
->count
);
5459 static u64
debug_taskcount_read(struct cgroup
*cont
, struct cftype
*cft
)
5461 return cgroup_task_count(cont
);
5464 static u64
current_css_set_read(struct cgroup
*cont
, struct cftype
*cft
)
5466 return (u64
)(unsigned long)current
->cgroups
;
5469 static u64
current_css_set_refcount_read(struct cgroup
*cont
,
5475 count
= atomic_read(¤t
->cgroups
->refcount
);
5480 static int current_css_set_cg_links_read(struct cgroup
*cont
,
5482 struct seq_file
*seq
)
5484 struct cg_cgroup_link
*link
;
5487 read_lock(&css_set_lock
);
5489 cg
= rcu_dereference(current
->cgroups
);
5490 list_for_each_entry(link
, &cg
->cg_links
, cg_link_list
) {
5491 struct cgroup
*c
= link
->cgrp
;
5495 name
= c
->dentry
->d_name
.name
;
5498 seq_printf(seq
, "Root %d group %s\n",
5499 c
->root
->hierarchy_id
, name
);
5502 read_unlock(&css_set_lock
);
5506 #define MAX_TASKS_SHOWN_PER_CSS 25
5507 static int cgroup_css_links_read(struct cgroup
*cont
,
5509 struct seq_file
*seq
)
5511 struct cg_cgroup_link
*link
;
5513 read_lock(&css_set_lock
);
5514 list_for_each_entry(link
, &cont
->css_sets
, cgrp_link_list
) {
5515 struct css_set
*cg
= link
->cg
;
5516 struct task_struct
*task
;
5518 seq_printf(seq
, "css_set %p\n", cg
);
5519 list_for_each_entry(task
, &cg
->tasks
, cg_list
) {
5520 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
) {
5521 seq_puts(seq
, " ...\n");
5524 seq_printf(seq
, " task %d\n",
5525 task_pid_vnr(task
));
5529 read_unlock(&css_set_lock
);
5533 static u64
releasable_read(struct cgroup
*cgrp
, struct cftype
*cft
)
5535 return test_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
5538 static struct cftype debug_files
[] = {
5540 .name
= "cgroup_refcount",
5541 .read_u64
= cgroup_refcount_read
,
5544 .name
= "taskcount",
5545 .read_u64
= debug_taskcount_read
,
5549 .name
= "current_css_set",
5550 .read_u64
= current_css_set_read
,
5554 .name
= "current_css_set_refcount",
5555 .read_u64
= current_css_set_refcount_read
,
5559 .name
= "current_css_set_cg_links",
5560 .read_seq_string
= current_css_set_cg_links_read
,
5564 .name
= "cgroup_css_links",
5565 .read_seq_string
= cgroup_css_links_read
,
5569 .name
= "releasable",
5570 .read_u64
= releasable_read
,
5576 struct cgroup_subsys debug_subsys
= {
5578 .css_alloc
= debug_css_alloc
,
5579 .css_free
= debug_css_free
,
5580 .subsys_id
= debug_subsys_id
,
5581 .base_cftypes
= debug_files
,
5583 #endif /* CONFIG_CGROUP_DEBUG */