2 * Generic process-grouping system.
4 * Based originally on the cpuset system, extracted by Paul Menage
5 * Copyright (C) 2006 Google, Inc
7 * Notifications support
8 * Copyright (C) 2009 Nokia Corporation
9 * Author: Kirill A. Shutemov
11 * Copyright notices from the original cpuset code:
12 * --------------------------------------------------
13 * Copyright (C) 2003 BULL SA.
14 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
16 * Portions derived from Patrick Mochel's sysfs code.
17 * sysfs is Copyright (c) 2001-3 Patrick Mochel
19 * 2003-10-10 Written by Simon Derr.
20 * 2003-10-22 Updates by Stephen Hemminger.
21 * 2004 May-July Rework by Paul Jackson.
22 * ---------------------------------------------------
24 * This file is subject to the terms and conditions of the GNU General Public
25 * License. See the file COPYING in the main directory of the Linux
26 * distribution for more details.
29 #include <linux/cgroup.h>
30 #include <linux/cred.h>
31 #include <linux/ctype.h>
32 #include <linux/errno.h>
33 #include <linux/init_task.h>
34 #include <linux/kernel.h>
35 #include <linux/list.h>
37 #include <linux/mutex.h>
38 #include <linux/mount.h>
39 #include <linux/pagemap.h>
40 #include <linux/proc_fs.h>
41 #include <linux/rcupdate.h>
42 #include <linux/sched.h>
43 #include <linux/backing-dev.h>
44 #include <linux/seq_file.h>
45 #include <linux/slab.h>
46 #include <linux/magic.h>
47 #include <linux/spinlock.h>
48 #include <linux/string.h>
49 #include <linux/sort.h>
50 #include <linux/kmod.h>
51 #include <linux/module.h>
52 #include <linux/delayacct.h>
53 #include <linux/cgroupstats.h>
54 #include <linux/hashtable.h>
55 #include <linux/namei.h>
56 #include <linux/pid_namespace.h>
57 #include <linux/idr.h>
58 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
59 #include <linux/eventfd.h>
60 #include <linux/poll.h>
61 #include <linux/flex_array.h> /* used in cgroup_attach_task */
62 #include <linux/kthread.h>
64 #include <linux/atomic.h>
66 /* css deactivation bias, makes css->refcnt negative to deny new trygets */
67 #define CSS_DEACT_BIAS INT_MIN
70 * cgroup_mutex is the master lock. Any modification to cgroup or its
71 * hierarchy must be performed while holding it.
73 * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify
74 * cgroupfs_root of any cgroup hierarchy - subsys list, flags,
75 * release_agent_path and so on. Modifying requires both cgroup_mutex and
76 * cgroup_root_mutex. Readers can acquire either of the two. This is to
77 * break the following locking order cycle.
79 * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem
80 * B. namespace_sem -> cgroup_mutex
82 * B happens only through cgroup_show_options() and using cgroup_root_mutex
85 #ifdef CONFIG_PROVE_RCU
86 DEFINE_MUTEX(cgroup_mutex
);
87 EXPORT_SYMBOL_GPL(cgroup_mutex
); /* only for task_subsys_state_check() */
89 static DEFINE_MUTEX(cgroup_mutex
);
92 static DEFINE_MUTEX(cgroup_root_mutex
);
95 * Generate an array of cgroup subsystem pointers. At boot time, this is
96 * populated with the built in subsystems, and modular subsystems are
97 * registered after that. The mutable section of this array is protected by
100 #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
101 #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
102 static struct cgroup_subsys
*subsys
[CGROUP_SUBSYS_COUNT
] = {
103 #include <linux/cgroup_subsys.h>
107 * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the
108 * subsystems that are otherwise unattached - it never has more than a
109 * single cgroup, and all tasks are part of that cgroup.
111 static struct cgroupfs_root rootnode
;
114 * cgroupfs file entry, pointed to from leaf dentry->d_fsdata.
117 struct list_head node
;
118 struct dentry
*dentry
;
123 * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
124 * cgroup_subsys->use_id != 0.
126 #define CSS_ID_MAX (65535)
129 * The css to which this ID points. This pointer is set to valid value
130 * after cgroup is populated. If cgroup is removed, this will be NULL.
131 * This pointer is expected to be RCU-safe because destroy()
132 * is called after synchronize_rcu(). But for safe use, css_tryget()
133 * should be used for avoiding race.
135 struct cgroup_subsys_state __rcu
*css
;
141 * Depth in hierarchy which this ID belongs to.
143 unsigned short depth
;
145 * ID is freed by RCU. (and lookup routine is RCU safe.)
147 struct rcu_head rcu_head
;
149 * Hierarchy of CSS ID belongs to.
151 unsigned short stack
[0]; /* Array of Length (depth+1) */
155 * cgroup_event represents events which userspace want to receive.
157 struct cgroup_event
{
159 * Cgroup which the event belongs to.
163 * Control file which the event associated.
167 * eventfd to signal userspace about the event.
169 struct eventfd_ctx
*eventfd
;
171 * Each of these stored in a list by the cgroup.
173 struct list_head list
;
175 * All fields below needed to unregister event when
176 * userspace closes eventfd.
179 wait_queue_head_t
*wqh
;
181 struct work_struct remove
;
184 /* The list of hierarchy roots */
186 static LIST_HEAD(roots
);
187 static int root_count
;
189 static DEFINE_IDA(hierarchy_ida
);
190 static int next_hierarchy_id
;
191 static DEFINE_SPINLOCK(hierarchy_id_lock
);
193 /* dummytop is a shorthand for the dummy hierarchy's top cgroup */
194 #define dummytop (&rootnode.top_cgroup)
196 static struct cgroup_name root_cgroup_name
= { .name
= "/" };
198 /* This flag indicates whether tasks in the fork and exit paths should
199 * check for fork/exit handlers to call. This avoids us having to do
200 * extra work in the fork/exit path if none of the subsystems need to
203 static int need_forkexit_callback __read_mostly
;
205 static int cgroup_destroy_locked(struct cgroup
*cgrp
);
206 static int cgroup_addrm_files(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
207 struct cftype cfts
[], bool is_add
);
209 static int css_unbias_refcnt(int refcnt
)
211 return refcnt
>= 0 ? refcnt
: refcnt
- CSS_DEACT_BIAS
;
214 /* the current nr of refs, always >= 0 whether @css is deactivated or not */
215 static int css_refcnt(struct cgroup_subsys_state
*css
)
217 int v
= atomic_read(&css
->refcnt
);
219 return css_unbias_refcnt(v
);
222 /* convenient tests for these bits */
223 inline int cgroup_is_removed(const struct cgroup
*cgrp
)
225 return test_bit(CGRP_REMOVED
, &cgrp
->flags
);
229 * cgroup_is_descendant - test ancestry
230 * @cgrp: the cgroup to be tested
231 * @ancestor: possible ancestor of @cgrp
233 * Test whether @cgrp is a descendant of @ancestor. It also returns %true
234 * if @cgrp == @ancestor. This function is safe to call as long as @cgrp
235 * and @ancestor are accessible.
237 bool cgroup_is_descendant(struct cgroup
*cgrp
, struct cgroup
*ancestor
)
240 if (cgrp
== ancestor
)
246 EXPORT_SYMBOL_GPL(cgroup_is_descendant
);
248 static int cgroup_is_releasable(const struct cgroup
*cgrp
)
251 (1 << CGRP_RELEASABLE
) |
252 (1 << CGRP_NOTIFY_ON_RELEASE
);
253 return (cgrp
->flags
& bits
) == bits
;
256 static int notify_on_release(const struct cgroup
*cgrp
)
258 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
262 * for_each_subsys() allows you to iterate on each subsystem attached to
263 * an active hierarchy
265 #define for_each_subsys(_root, _ss) \
266 list_for_each_entry(_ss, &_root->subsys_list, sibling)
268 /* for_each_active_root() allows you to iterate across the active hierarchies */
269 #define for_each_active_root(_root) \
270 list_for_each_entry(_root, &roots, root_list)
272 static inline struct cgroup
*__d_cgrp(struct dentry
*dentry
)
274 return dentry
->d_fsdata
;
277 static inline struct cfent
*__d_cfe(struct dentry
*dentry
)
279 return dentry
->d_fsdata
;
282 static inline struct cftype
*__d_cft(struct dentry
*dentry
)
284 return __d_cfe(dentry
)->type
;
288 * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
289 * @cgrp: the cgroup to be checked for liveness
291 * On success, returns true; the mutex should be later unlocked. On
292 * failure returns false with no lock held.
294 static bool cgroup_lock_live_group(struct cgroup
*cgrp
)
296 mutex_lock(&cgroup_mutex
);
297 if (cgroup_is_removed(cgrp
)) {
298 mutex_unlock(&cgroup_mutex
);
304 /* the list of cgroups eligible for automatic release. Protected by
305 * release_list_lock */
306 static LIST_HEAD(release_list
);
307 static DEFINE_RAW_SPINLOCK(release_list_lock
);
308 static void cgroup_release_agent(struct work_struct
*work
);
309 static DECLARE_WORK(release_agent_work
, cgroup_release_agent
);
310 static void check_for_release(struct cgroup
*cgrp
);
312 /* Link structure for associating css_set objects with cgroups */
313 struct cg_cgroup_link
{
315 * List running through cg_cgroup_links associated with a
316 * cgroup, anchored on cgroup->css_sets
318 struct list_head cgrp_link_list
;
321 * List running through cg_cgroup_links pointing at a
322 * single css_set object, anchored on css_set->cg_links
324 struct list_head cg_link_list
;
328 /* The default css_set - used by init and its children prior to any
329 * hierarchies being mounted. It contains a pointer to the root state
330 * for each subsystem. Also used to anchor the list of css_sets. Not
331 * reference-counted, to improve performance when child cgroups
332 * haven't been created.
335 static struct css_set init_css_set
;
336 static struct cg_cgroup_link init_css_set_link
;
338 static int cgroup_init_idr(struct cgroup_subsys
*ss
,
339 struct cgroup_subsys_state
*css
);
341 /* css_set_lock protects the list of css_set objects, and the
342 * chain of tasks off each css_set. Nests outside task->alloc_lock
343 * due to cgroup_iter_start() */
344 static DEFINE_RWLOCK(css_set_lock
);
345 static int css_set_count
;
348 * hash table for cgroup groups. This improves the performance to find
349 * an existing css_set. This hash doesn't (currently) take into
350 * account cgroups in empty hierarchies.
352 #define CSS_SET_HASH_BITS 7
353 static DEFINE_HASHTABLE(css_set_table
, CSS_SET_HASH_BITS
);
355 static unsigned long css_set_hash(struct cgroup_subsys_state
*css
[])
358 unsigned long key
= 0UL;
360 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++)
361 key
+= (unsigned long)css
[i
];
362 key
= (key
>> 16) ^ key
;
367 /* We don't maintain the lists running through each css_set to its
368 * task until after the first call to cgroup_iter_start(). This
369 * reduces the fork()/exit() overhead for people who have cgroups
370 * compiled into their kernel but not actually in use */
371 static int use_task_css_set_links __read_mostly
;
373 static void __put_css_set(struct css_set
*cg
, int taskexit
)
375 struct cg_cgroup_link
*link
;
376 struct cg_cgroup_link
*saved_link
;
378 * Ensure that the refcount doesn't hit zero while any readers
379 * can see it. Similar to atomic_dec_and_lock(), but for an
382 if (atomic_add_unless(&cg
->refcount
, -1, 1))
384 write_lock(&css_set_lock
);
385 if (!atomic_dec_and_test(&cg
->refcount
)) {
386 write_unlock(&css_set_lock
);
390 /* This css_set is dead. unlink it and release cgroup refcounts */
391 hash_del(&cg
->hlist
);
394 list_for_each_entry_safe(link
, saved_link
, &cg
->cg_links
,
396 struct cgroup
*cgrp
= link
->cgrp
;
397 list_del(&link
->cg_link_list
);
398 list_del(&link
->cgrp_link_list
);
401 * We may not be holding cgroup_mutex, and if cgrp->count is
402 * dropped to 0 the cgroup can be destroyed at any time, hence
403 * rcu_read_lock is used to keep it alive.
406 if (atomic_dec_and_test(&cgrp
->count
) &&
407 notify_on_release(cgrp
)) {
409 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
410 check_for_release(cgrp
);
417 write_unlock(&css_set_lock
);
418 kfree_rcu(cg
, rcu_head
);
422 * refcounted get/put for css_set objects
424 static inline void get_css_set(struct css_set
*cg
)
426 atomic_inc(&cg
->refcount
);
429 static inline void put_css_set(struct css_set
*cg
)
431 __put_css_set(cg
, 0);
434 static inline void put_css_set_taskexit(struct css_set
*cg
)
436 __put_css_set(cg
, 1);
440 * compare_css_sets - helper function for find_existing_css_set().
441 * @cg: candidate css_set being tested
442 * @old_cg: existing css_set for a task
443 * @new_cgrp: cgroup that's being entered by the task
444 * @template: desired set of css pointers in css_set (pre-calculated)
446 * Returns true if "cg" matches "old_cg" except for the hierarchy
447 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
449 static bool compare_css_sets(struct css_set
*cg
,
450 struct css_set
*old_cg
,
451 struct cgroup
*new_cgrp
,
452 struct cgroup_subsys_state
*template[])
454 struct list_head
*l1
, *l2
;
456 if (memcmp(template, cg
->subsys
, sizeof(cg
->subsys
))) {
457 /* Not all subsystems matched */
462 * Compare cgroup pointers in order to distinguish between
463 * different cgroups in heirarchies with no subsystems. We
464 * could get by with just this check alone (and skip the
465 * memcmp above) but on most setups the memcmp check will
466 * avoid the need for this more expensive check on almost all
471 l2
= &old_cg
->cg_links
;
473 struct cg_cgroup_link
*cgl1
, *cgl2
;
474 struct cgroup
*cg1
, *cg2
;
478 /* See if we reached the end - both lists are equal length. */
479 if (l1
== &cg
->cg_links
) {
480 BUG_ON(l2
!= &old_cg
->cg_links
);
483 BUG_ON(l2
== &old_cg
->cg_links
);
485 /* Locate the cgroups associated with these links. */
486 cgl1
= list_entry(l1
, struct cg_cgroup_link
, cg_link_list
);
487 cgl2
= list_entry(l2
, struct cg_cgroup_link
, cg_link_list
);
490 /* Hierarchies should be linked in the same order. */
491 BUG_ON(cg1
->root
!= cg2
->root
);
494 * If this hierarchy is the hierarchy of the cgroup
495 * that's changing, then we need to check that this
496 * css_set points to the new cgroup; if it's any other
497 * hierarchy, then this css_set should point to the
498 * same cgroup as the old css_set.
500 if (cg1
->root
== new_cgrp
->root
) {
512 * find_existing_css_set() is a helper for
513 * find_css_set(), and checks to see whether an existing
514 * css_set is suitable.
516 * oldcg: the cgroup group that we're using before the cgroup
519 * cgrp: the cgroup that we're moving into
521 * template: location in which to build the desired set of subsystem
522 * state objects for the new cgroup group
524 static struct css_set
*find_existing_css_set(
525 struct css_set
*oldcg
,
527 struct cgroup_subsys_state
*template[])
530 struct cgroupfs_root
*root
= cgrp
->root
;
535 * Build the set of subsystem state objects that we want to see in the
536 * new css_set. while subsystems can change globally, the entries here
537 * won't change, so no need for locking.
539 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
540 if (root
->subsys_mask
& (1UL << i
)) {
541 /* Subsystem is in this hierarchy. So we want
542 * the subsystem state from the new
544 template[i
] = cgrp
->subsys
[i
];
546 /* Subsystem is not in this hierarchy, so we
547 * don't want to change the subsystem state */
548 template[i
] = oldcg
->subsys
[i
];
552 key
= css_set_hash(template);
553 hash_for_each_possible(css_set_table
, cg
, hlist
, key
) {
554 if (!compare_css_sets(cg
, oldcg
, cgrp
, template))
557 /* This css_set matches what we need */
561 /* No existing cgroup group matched */
565 static void free_cg_links(struct list_head
*tmp
)
567 struct cg_cgroup_link
*link
;
568 struct cg_cgroup_link
*saved_link
;
570 list_for_each_entry_safe(link
, saved_link
, tmp
, cgrp_link_list
) {
571 list_del(&link
->cgrp_link_list
);
577 * allocate_cg_links() allocates "count" cg_cgroup_link structures
578 * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
579 * success or a negative error
581 static int allocate_cg_links(int count
, struct list_head
*tmp
)
583 struct cg_cgroup_link
*link
;
586 for (i
= 0; i
< count
; i
++) {
587 link
= kmalloc(sizeof(*link
), GFP_KERNEL
);
592 list_add(&link
->cgrp_link_list
, tmp
);
598 * link_css_set - a helper function to link a css_set to a cgroup
599 * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links()
600 * @cg: the css_set to be linked
601 * @cgrp: the destination cgroup
603 static void link_css_set(struct list_head
*tmp_cg_links
,
604 struct css_set
*cg
, struct cgroup
*cgrp
)
606 struct cg_cgroup_link
*link
;
608 BUG_ON(list_empty(tmp_cg_links
));
609 link
= list_first_entry(tmp_cg_links
, struct cg_cgroup_link
,
613 atomic_inc(&cgrp
->count
);
614 list_move(&link
->cgrp_link_list
, &cgrp
->css_sets
);
616 * Always add links to the tail of the list so that the list
617 * is sorted by order of hierarchy creation
619 list_add_tail(&link
->cg_link_list
, &cg
->cg_links
);
623 * find_css_set() takes an existing cgroup group and a
624 * cgroup object, and returns a css_set object that's
625 * equivalent to the old group, but with the given cgroup
626 * substituted into the appropriate hierarchy. Must be called with
629 static struct css_set
*find_css_set(
630 struct css_set
*oldcg
, struct cgroup
*cgrp
)
633 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
];
635 struct list_head tmp_cg_links
;
637 struct cg_cgroup_link
*link
;
640 /* First see if we already have a cgroup group that matches
642 read_lock(&css_set_lock
);
643 res
= find_existing_css_set(oldcg
, cgrp
, template);
646 read_unlock(&css_set_lock
);
651 res
= kmalloc(sizeof(*res
), GFP_KERNEL
);
655 /* Allocate all the cg_cgroup_link objects that we'll need */
656 if (allocate_cg_links(root_count
, &tmp_cg_links
) < 0) {
661 atomic_set(&res
->refcount
, 1);
662 INIT_LIST_HEAD(&res
->cg_links
);
663 INIT_LIST_HEAD(&res
->tasks
);
664 INIT_HLIST_NODE(&res
->hlist
);
666 /* Copy the set of subsystem state objects generated in
667 * find_existing_css_set() */
668 memcpy(res
->subsys
, template, sizeof(res
->subsys
));
670 write_lock(&css_set_lock
);
671 /* Add reference counts and links from the new css_set. */
672 list_for_each_entry(link
, &oldcg
->cg_links
, cg_link_list
) {
673 struct cgroup
*c
= link
->cgrp
;
674 if (c
->root
== cgrp
->root
)
676 link_css_set(&tmp_cg_links
, res
, c
);
679 BUG_ON(!list_empty(&tmp_cg_links
));
683 /* Add this cgroup group to the hash table */
684 key
= css_set_hash(res
->subsys
);
685 hash_add(css_set_table
, &res
->hlist
, key
);
687 write_unlock(&css_set_lock
);
693 * Return the cgroup for "task" from the given hierarchy. Must be
694 * called with cgroup_mutex held.
696 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
697 struct cgroupfs_root
*root
)
700 struct cgroup
*res
= NULL
;
702 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
703 read_lock(&css_set_lock
);
705 * No need to lock the task - since we hold cgroup_mutex the
706 * task can't change groups, so the only thing that can happen
707 * is that it exits and its css is set back to init_css_set.
710 if (css
== &init_css_set
) {
711 res
= &root
->top_cgroup
;
713 struct cg_cgroup_link
*link
;
714 list_for_each_entry(link
, &css
->cg_links
, cg_link_list
) {
715 struct cgroup
*c
= link
->cgrp
;
716 if (c
->root
== root
) {
722 read_unlock(&css_set_lock
);
728 * There is one global cgroup mutex. We also require taking
729 * task_lock() when dereferencing a task's cgroup subsys pointers.
730 * See "The task_lock() exception", at the end of this comment.
732 * A task must hold cgroup_mutex to modify cgroups.
734 * Any task can increment and decrement the count field without lock.
735 * So in general, code holding cgroup_mutex can't rely on the count
736 * field not changing. However, if the count goes to zero, then only
737 * cgroup_attach_task() can increment it again. Because a count of zero
738 * means that no tasks are currently attached, therefore there is no
739 * way a task attached to that cgroup can fork (the other way to
740 * increment the count). So code holding cgroup_mutex can safely
741 * assume that if the count is zero, it will stay zero. Similarly, if
742 * a task holds cgroup_mutex on a cgroup with zero count, it
743 * knows that the cgroup won't be removed, as cgroup_rmdir()
746 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
747 * (usually) take cgroup_mutex. These are the two most performance
748 * critical pieces of code here. The exception occurs on cgroup_exit(),
749 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
750 * is taken, and if the cgroup count is zero, a usermode call made
751 * to the release agent with the name of the cgroup (path relative to
752 * the root of cgroup file system) as the argument.
754 * A cgroup can only be deleted if both its 'count' of using tasks
755 * is zero, and its list of 'children' cgroups is empty. Since all
756 * tasks in the system use _some_ cgroup, and since there is always at
757 * least one task in the system (init, pid == 1), therefore, top_cgroup
758 * always has either children cgroups and/or using tasks. So we don't
759 * need a special hack to ensure that top_cgroup cannot be deleted.
761 * The task_lock() exception
763 * The need for this exception arises from the action of
764 * cgroup_attach_task(), which overwrites one task's cgroup pointer with
765 * another. It does so using cgroup_mutex, however there are
766 * several performance critical places that need to reference
767 * task->cgroup without the expense of grabbing a system global
768 * mutex. Therefore except as noted below, when dereferencing or, as
769 * in cgroup_attach_task(), modifying a task's cgroup pointer we use
770 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
771 * the task_struct routinely used for such matters.
773 * P.S. One more locking exception. RCU is used to guard the
774 * update of a tasks cgroup pointer by cgroup_attach_task()
778 * A couple of forward declarations required, due to cyclic reference loop:
779 * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir ->
780 * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations
784 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
);
785 static struct dentry
*cgroup_lookup(struct inode
*, struct dentry
*, unsigned int);
786 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
);
787 static int cgroup_populate_dir(struct cgroup
*cgrp
, bool base_files
,
788 unsigned long subsys_mask
);
789 static const struct inode_operations cgroup_dir_inode_operations
;
790 static const struct file_operations proc_cgroupstats_operations
;
792 static struct backing_dev_info cgroup_backing_dev_info
= {
794 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
,
797 static int alloc_css_id(struct cgroup_subsys
*ss
,
798 struct cgroup
*parent
, struct cgroup
*child
);
800 static struct inode
*cgroup_new_inode(umode_t mode
, struct super_block
*sb
)
802 struct inode
*inode
= new_inode(sb
);
805 inode
->i_ino
= get_next_ino();
806 inode
->i_mode
= mode
;
807 inode
->i_uid
= current_fsuid();
808 inode
->i_gid
= current_fsgid();
809 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
810 inode
->i_mapping
->backing_dev_info
= &cgroup_backing_dev_info
;
815 static struct cgroup_name
*cgroup_alloc_name(struct dentry
*dentry
)
817 struct cgroup_name
*name
;
819 name
= kmalloc(sizeof(*name
) + dentry
->d_name
.len
+ 1, GFP_KERNEL
);
822 strcpy(name
->name
, dentry
->d_name
.name
);
826 static void cgroup_free_fn(struct work_struct
*work
)
828 struct cgroup
*cgrp
= container_of(work
, struct cgroup
, free_work
);
829 struct cgroup_subsys
*ss
;
831 mutex_lock(&cgroup_mutex
);
833 * Release the subsystem state objects.
835 for_each_subsys(cgrp
->root
, ss
)
838 cgrp
->root
->number_of_cgroups
--;
839 mutex_unlock(&cgroup_mutex
);
842 * We get a ref to the parent's dentry, and put the ref when
843 * this cgroup is being freed, so it's guaranteed that the
844 * parent won't be destroyed before its children.
846 dput(cgrp
->parent
->dentry
);
849 * Drop the active superblock reference that we took when we
852 deactivate_super(cgrp
->root
->sb
);
855 * if we're getting rid of the cgroup, refcount should ensure
856 * that there are no pidlists left.
858 BUG_ON(!list_empty(&cgrp
->pidlists
));
860 simple_xattrs_free(&cgrp
->xattrs
);
862 ida_simple_remove(&cgrp
->root
->cgroup_ida
, cgrp
->id
);
863 kfree(rcu_dereference_raw(cgrp
->name
));
867 static void cgroup_free_rcu(struct rcu_head
*head
)
869 struct cgroup
*cgrp
= container_of(head
, struct cgroup
, rcu_head
);
871 schedule_work(&cgrp
->free_work
);
874 static void cgroup_diput(struct dentry
*dentry
, struct inode
*inode
)
876 /* is dentry a directory ? if so, kfree() associated cgroup */
877 if (S_ISDIR(inode
->i_mode
)) {
878 struct cgroup
*cgrp
= dentry
->d_fsdata
;
880 BUG_ON(!(cgroup_is_removed(cgrp
)));
881 call_rcu(&cgrp
->rcu_head
, cgroup_free_rcu
);
883 struct cfent
*cfe
= __d_cfe(dentry
);
884 struct cgroup
*cgrp
= dentry
->d_parent
->d_fsdata
;
885 struct cftype
*cft
= cfe
->type
;
887 WARN_ONCE(!list_empty(&cfe
->node
) &&
888 cgrp
!= &cgrp
->root
->top_cgroup
,
889 "cfe still linked for %s\n", cfe
->type
->name
);
891 simple_xattrs_free(&cft
->xattrs
);
896 static int cgroup_delete(const struct dentry
*d
)
901 static void remove_dir(struct dentry
*d
)
903 struct dentry
*parent
= dget(d
->d_parent
);
906 simple_rmdir(parent
->d_inode
, d
);
910 static void cgroup_rm_file(struct cgroup
*cgrp
, const struct cftype
*cft
)
914 lockdep_assert_held(&cgrp
->dentry
->d_inode
->i_mutex
);
915 lockdep_assert_held(&cgroup_mutex
);
918 * If we're doing cleanup due to failure of cgroup_create(),
919 * the corresponding @cfe may not exist.
921 list_for_each_entry(cfe
, &cgrp
->files
, node
) {
922 struct dentry
*d
= cfe
->dentry
;
924 if (cft
&& cfe
->type
!= cft
)
929 simple_unlink(cgrp
->dentry
->d_inode
, d
);
930 list_del_init(&cfe
->node
);
938 * cgroup_clear_directory - selective removal of base and subsystem files
939 * @dir: directory containing the files
940 * @base_files: true if the base files should be removed
941 * @subsys_mask: mask of the subsystem ids whose files should be removed
943 static void cgroup_clear_directory(struct dentry
*dir
, bool base_files
,
944 unsigned long subsys_mask
)
946 struct cgroup
*cgrp
= __d_cgrp(dir
);
947 struct cgroup_subsys
*ss
;
949 for_each_subsys(cgrp
->root
, ss
) {
950 struct cftype_set
*set
;
951 if (!test_bit(ss
->subsys_id
, &subsys_mask
))
953 list_for_each_entry(set
, &ss
->cftsets
, node
)
954 cgroup_addrm_files(cgrp
, NULL
, set
->cfts
, false);
957 while (!list_empty(&cgrp
->files
))
958 cgroup_rm_file(cgrp
, NULL
);
963 * NOTE : the dentry must have been dget()'ed
965 static void cgroup_d_remove_dir(struct dentry
*dentry
)
967 struct dentry
*parent
;
968 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
970 cgroup_clear_directory(dentry
, true, root
->subsys_mask
);
972 parent
= dentry
->d_parent
;
973 spin_lock(&parent
->d_lock
);
974 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
975 list_del_init(&dentry
->d_u
.d_child
);
976 spin_unlock(&dentry
->d_lock
);
977 spin_unlock(&parent
->d_lock
);
982 * Call with cgroup_mutex held. Drops reference counts on modules, including
983 * any duplicate ones that parse_cgroupfs_options took. If this function
984 * returns an error, no reference counts are touched.
986 static int rebind_subsystems(struct cgroupfs_root
*root
,
987 unsigned long final_subsys_mask
)
989 unsigned long added_mask
, removed_mask
;
990 struct cgroup
*cgrp
= &root
->top_cgroup
;
993 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
994 BUG_ON(!mutex_is_locked(&cgroup_root_mutex
));
996 removed_mask
= root
->actual_subsys_mask
& ~final_subsys_mask
;
997 added_mask
= final_subsys_mask
& ~root
->actual_subsys_mask
;
998 /* Check that any added subsystems are currently free */
999 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1000 unsigned long bit
= 1UL << i
;
1001 struct cgroup_subsys
*ss
= subsys
[i
];
1002 if (!(bit
& added_mask
))
1005 * Nobody should tell us to do a subsys that doesn't exist:
1006 * parse_cgroupfs_options should catch that case and refcounts
1007 * ensure that subsystems won't disappear once selected.
1010 if (ss
->root
!= &rootnode
) {
1011 /* Subsystem isn't free */
1016 /* Currently we don't handle adding/removing subsystems when
1017 * any child cgroups exist. This is theoretically supportable
1018 * but involves complex error handling, so it's being left until
1020 if (root
->number_of_cgroups
> 1)
1023 /* Process each subsystem */
1024 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1025 struct cgroup_subsys
*ss
= subsys
[i
];
1026 unsigned long bit
= 1UL << i
;
1027 if (bit
& added_mask
) {
1028 /* We're binding this subsystem to this hierarchy */
1030 BUG_ON(cgrp
->subsys
[i
]);
1031 BUG_ON(!dummytop
->subsys
[i
]);
1032 BUG_ON(dummytop
->subsys
[i
]->cgroup
!= dummytop
);
1033 cgrp
->subsys
[i
] = dummytop
->subsys
[i
];
1034 cgrp
->subsys
[i
]->cgroup
= cgrp
;
1035 list_move(&ss
->sibling
, &root
->subsys_list
);
1039 /* refcount was already taken, and we're keeping it */
1040 } else if (bit
& removed_mask
) {
1041 /* We're removing this subsystem */
1043 BUG_ON(cgrp
->subsys
[i
] != dummytop
->subsys
[i
]);
1044 BUG_ON(cgrp
->subsys
[i
]->cgroup
!= cgrp
);
1047 dummytop
->subsys
[i
]->cgroup
= dummytop
;
1048 cgrp
->subsys
[i
] = NULL
;
1049 subsys
[i
]->root
= &rootnode
;
1050 list_move(&ss
->sibling
, &rootnode
.subsys_list
);
1051 /* subsystem is now free - drop reference on module */
1052 module_put(ss
->module
);
1053 } else if (bit
& final_subsys_mask
) {
1054 /* Subsystem state should already exist */
1056 BUG_ON(!cgrp
->subsys
[i
]);
1058 * a refcount was taken, but we already had one, so
1059 * drop the extra reference.
1061 module_put(ss
->module
);
1062 #ifdef CONFIG_MODULE_UNLOAD
1063 BUG_ON(ss
->module
&& !module_refcount(ss
->module
));
1066 /* Subsystem state shouldn't exist */
1067 BUG_ON(cgrp
->subsys
[i
]);
1070 root
->subsys_mask
= root
->actual_subsys_mask
= final_subsys_mask
;
1075 static int cgroup_show_options(struct seq_file
*seq
, struct dentry
*dentry
)
1077 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
1078 struct cgroup_subsys
*ss
;
1080 mutex_lock(&cgroup_root_mutex
);
1081 for_each_subsys(root
, ss
)
1082 seq_printf(seq
, ",%s", ss
->name
);
1083 if (root
->flags
& CGRP_ROOT_SANE_BEHAVIOR
)
1084 seq_puts(seq
, ",sane_behavior");
1085 if (root
->flags
& CGRP_ROOT_NOPREFIX
)
1086 seq_puts(seq
, ",noprefix");
1087 if (root
->flags
& CGRP_ROOT_XATTR
)
1088 seq_puts(seq
, ",xattr");
1089 if (strlen(root
->release_agent_path
))
1090 seq_printf(seq
, ",release_agent=%s", root
->release_agent_path
);
1091 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
))
1092 seq_puts(seq
, ",clone_children");
1093 if (strlen(root
->name
))
1094 seq_printf(seq
, ",name=%s", root
->name
);
1095 mutex_unlock(&cgroup_root_mutex
);
1099 struct cgroup_sb_opts
{
1100 unsigned long subsys_mask
;
1101 unsigned long flags
;
1102 char *release_agent
;
1103 bool cpuset_clone_children
;
1105 /* User explicitly requested empty subsystem */
1108 struct cgroupfs_root
*new_root
;
1113 * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call
1114 * with cgroup_mutex held to protect the subsys[] array. This function takes
1115 * refcounts on subsystems to be used, unless it returns error, in which case
1116 * no refcounts are taken.
1118 static int parse_cgroupfs_options(char *data
, struct cgroup_sb_opts
*opts
)
1120 char *token
, *o
= data
;
1121 bool all_ss
= false, one_ss
= false;
1122 unsigned long mask
= (unsigned long)-1;
1124 bool module_pin_failed
= false;
1126 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
1128 #ifdef CONFIG_CPUSETS
1129 mask
= ~(1UL << cpuset_subsys_id
);
1132 memset(opts
, 0, sizeof(*opts
));
1134 while ((token
= strsep(&o
, ",")) != NULL
) {
1137 if (!strcmp(token
, "none")) {
1138 /* Explicitly have no subsystems */
1142 if (!strcmp(token
, "all")) {
1143 /* Mutually exclusive option 'all' + subsystem name */
1149 if (!strcmp(token
, "__DEVEL__sane_behavior")) {
1150 opts
->flags
|= CGRP_ROOT_SANE_BEHAVIOR
;
1153 if (!strcmp(token
, "noprefix")) {
1154 opts
->flags
|= CGRP_ROOT_NOPREFIX
;
1157 if (!strcmp(token
, "clone_children")) {
1158 opts
->cpuset_clone_children
= true;
1161 if (!strcmp(token
, "xattr")) {
1162 opts
->flags
|= CGRP_ROOT_XATTR
;
1165 if (!strncmp(token
, "release_agent=", 14)) {
1166 /* Specifying two release agents is forbidden */
1167 if (opts
->release_agent
)
1169 opts
->release_agent
=
1170 kstrndup(token
+ 14, PATH_MAX
- 1, GFP_KERNEL
);
1171 if (!opts
->release_agent
)
1175 if (!strncmp(token
, "name=", 5)) {
1176 const char *name
= token
+ 5;
1177 /* Can't specify an empty name */
1180 /* Must match [\w.-]+ */
1181 for (i
= 0; i
< strlen(name
); i
++) {
1185 if ((c
== '.') || (c
== '-') || (c
== '_'))
1189 /* Specifying two names is forbidden */
1192 opts
->name
= kstrndup(name
,
1193 MAX_CGROUP_ROOT_NAMELEN
- 1,
1201 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1202 struct cgroup_subsys
*ss
= subsys
[i
];
1205 if (strcmp(token
, ss
->name
))
1210 /* Mutually exclusive option 'all' + subsystem name */
1213 set_bit(i
, &opts
->subsys_mask
);
1218 if (i
== CGROUP_SUBSYS_COUNT
)
1223 * If the 'all' option was specified select all the subsystems,
1224 * otherwise if 'none', 'name=' and a subsystem name options
1225 * were not specified, let's default to 'all'
1227 if (all_ss
|| (!one_ss
&& !opts
->none
&& !opts
->name
)) {
1228 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1229 struct cgroup_subsys
*ss
= subsys
[i
];
1234 set_bit(i
, &opts
->subsys_mask
);
1238 /* Consistency checks */
1240 if (opts
->flags
& CGRP_ROOT_SANE_BEHAVIOR
) {
1241 pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
1243 if (opts
->flags
& CGRP_ROOT_NOPREFIX
) {
1244 pr_err("cgroup: sane_behavior: noprefix is not allowed\n");
1248 if (opts
->cpuset_clone_children
) {
1249 pr_err("cgroup: sane_behavior: clone_children is not allowed\n");
1255 * Option noprefix was introduced just for backward compatibility
1256 * with the old cpuset, so we allow noprefix only if mounting just
1257 * the cpuset subsystem.
1259 if ((opts
->flags
& CGRP_ROOT_NOPREFIX
) && (opts
->subsys_mask
& mask
))
1263 /* Can't specify "none" and some subsystems */
1264 if (opts
->subsys_mask
&& opts
->none
)
1268 * We either have to specify by name or by subsystems. (So all
1269 * empty hierarchies must have a name).
1271 if (!opts
->subsys_mask
&& !opts
->name
)
1275 * Grab references on all the modules we'll need, so the subsystems
1276 * don't dance around before rebind_subsystems attaches them. This may
1277 * take duplicate reference counts on a subsystem that's already used,
1278 * but rebind_subsystems handles this case.
1280 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1281 unsigned long bit
= 1UL << i
;
1283 if (!(bit
& opts
->subsys_mask
))
1285 if (!try_module_get(subsys
[i
]->module
)) {
1286 module_pin_failed
= true;
1290 if (module_pin_failed
) {
1292 * oops, one of the modules was going away. this means that we
1293 * raced with a module_delete call, and to the user this is
1294 * essentially a "subsystem doesn't exist" case.
1296 for (i
--; i
>= 0; i
--) {
1297 /* drop refcounts only on the ones we took */
1298 unsigned long bit
= 1UL << i
;
1300 if (!(bit
& opts
->subsys_mask
))
1302 module_put(subsys
[i
]->module
);
1310 static void drop_parsed_module_refcounts(unsigned long subsys_mask
)
1313 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
1314 unsigned long bit
= 1UL << i
;
1316 if (!(bit
& subsys_mask
))
1318 module_put(subsys
[i
]->module
);
1322 static int cgroup_remount(struct super_block
*sb
, int *flags
, char *data
)
1325 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1326 struct cgroup
*cgrp
= &root
->top_cgroup
;
1327 struct cgroup_sb_opts opts
;
1328 unsigned long added_mask
, removed_mask
;
1330 if (root
->flags
& CGRP_ROOT_SANE_BEHAVIOR
) {
1331 pr_err("cgroup: sane_behavior: remount is not allowed\n");
1335 mutex_lock(&cgrp
->dentry
->d_inode
->i_mutex
);
1336 mutex_lock(&cgroup_mutex
);
1337 mutex_lock(&cgroup_root_mutex
);
1339 /* See what subsystems are wanted */
1340 ret
= parse_cgroupfs_options(data
, &opts
);
1344 if (opts
.subsys_mask
!= root
->actual_subsys_mask
|| opts
.release_agent
)
1345 pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
1346 task_tgid_nr(current
), current
->comm
);
1348 added_mask
= opts
.subsys_mask
& ~root
->subsys_mask
;
1349 removed_mask
= root
->subsys_mask
& ~opts
.subsys_mask
;
1351 /* Don't allow flags or name to change at remount */
1352 if (opts
.flags
!= root
->flags
||
1353 (opts
.name
&& strcmp(opts
.name
, root
->name
))) {
1355 drop_parsed_module_refcounts(opts
.subsys_mask
);
1360 * Clear out the files of subsystems that should be removed, do
1361 * this before rebind_subsystems, since rebind_subsystems may
1362 * change this hierarchy's subsys_list.
1364 cgroup_clear_directory(cgrp
->dentry
, false, removed_mask
);
1366 ret
= rebind_subsystems(root
, opts
.subsys_mask
);
1368 /* rebind_subsystems failed, re-populate the removed files */
1369 cgroup_populate_dir(cgrp
, false, removed_mask
);
1370 drop_parsed_module_refcounts(opts
.subsys_mask
);
1374 /* re-populate subsystem files */
1375 cgroup_populate_dir(cgrp
, false, added_mask
);
1377 if (opts
.release_agent
)
1378 strcpy(root
->release_agent_path
, opts
.release_agent
);
1380 kfree(opts
.release_agent
);
1382 mutex_unlock(&cgroup_root_mutex
);
1383 mutex_unlock(&cgroup_mutex
);
1384 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
1388 static const struct super_operations cgroup_ops
= {
1389 .statfs
= simple_statfs
,
1390 .drop_inode
= generic_delete_inode
,
1391 .show_options
= cgroup_show_options
,
1392 .remount_fs
= cgroup_remount
,
1395 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1397 INIT_LIST_HEAD(&cgrp
->sibling
);
1398 INIT_LIST_HEAD(&cgrp
->children
);
1399 INIT_LIST_HEAD(&cgrp
->files
);
1400 INIT_LIST_HEAD(&cgrp
->css_sets
);
1401 INIT_LIST_HEAD(&cgrp
->allcg_node
);
1402 INIT_LIST_HEAD(&cgrp
->release_list
);
1403 INIT_LIST_HEAD(&cgrp
->pidlists
);
1404 INIT_WORK(&cgrp
->free_work
, cgroup_free_fn
);
1405 mutex_init(&cgrp
->pidlist_mutex
);
1406 INIT_LIST_HEAD(&cgrp
->event_list
);
1407 spin_lock_init(&cgrp
->event_list_lock
);
1408 simple_xattrs_init(&cgrp
->xattrs
);
1411 static void init_cgroup_root(struct cgroupfs_root
*root
)
1413 struct cgroup
*cgrp
= &root
->top_cgroup
;
1415 INIT_LIST_HEAD(&root
->subsys_list
);
1416 INIT_LIST_HEAD(&root
->root_list
);
1417 INIT_LIST_HEAD(&root
->allcg_list
);
1418 root
->number_of_cgroups
= 1;
1420 cgrp
->name
= &root_cgroup_name
;
1421 cgrp
->top_cgroup
= cgrp
;
1422 init_cgroup_housekeeping(cgrp
);
1423 list_add_tail(&cgrp
->allcg_node
, &root
->allcg_list
);
1426 static bool init_root_id(struct cgroupfs_root
*root
)
1431 if (!ida_pre_get(&hierarchy_ida
, GFP_KERNEL
))
1433 spin_lock(&hierarchy_id_lock
);
1434 /* Try to allocate the next unused ID */
1435 ret
= ida_get_new_above(&hierarchy_ida
, next_hierarchy_id
,
1436 &root
->hierarchy_id
);
1438 /* Try again starting from 0 */
1439 ret
= ida_get_new(&hierarchy_ida
, &root
->hierarchy_id
);
1441 next_hierarchy_id
= root
->hierarchy_id
+ 1;
1442 } else if (ret
!= -EAGAIN
) {
1443 /* Can only get here if the 31-bit IDR is full ... */
1446 spin_unlock(&hierarchy_id_lock
);
1451 static int cgroup_test_super(struct super_block
*sb
, void *data
)
1453 struct cgroup_sb_opts
*opts
= data
;
1454 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1456 /* If we asked for a name then it must match */
1457 if (opts
->name
&& strcmp(opts
->name
, root
->name
))
1461 * If we asked for subsystems (or explicitly for no
1462 * subsystems) then they must match
1464 if ((opts
->subsys_mask
|| opts
->none
)
1465 && (opts
->subsys_mask
!= root
->subsys_mask
))
1471 static struct cgroupfs_root
*cgroup_root_from_opts(struct cgroup_sb_opts
*opts
)
1473 struct cgroupfs_root
*root
;
1475 if (!opts
->subsys_mask
&& !opts
->none
)
1478 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
1480 return ERR_PTR(-ENOMEM
);
1482 if (!init_root_id(root
)) {
1484 return ERR_PTR(-ENOMEM
);
1486 init_cgroup_root(root
);
1488 root
->subsys_mask
= opts
->subsys_mask
;
1489 root
->flags
= opts
->flags
;
1490 ida_init(&root
->cgroup_ida
);
1491 if (opts
->release_agent
)
1492 strcpy(root
->release_agent_path
, opts
->release_agent
);
1494 strcpy(root
->name
, opts
->name
);
1495 if (opts
->cpuset_clone_children
)
1496 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
);
1500 static void cgroup_drop_root(struct cgroupfs_root
*root
)
1505 BUG_ON(!root
->hierarchy_id
);
1506 spin_lock(&hierarchy_id_lock
);
1507 ida_remove(&hierarchy_ida
, root
->hierarchy_id
);
1508 spin_unlock(&hierarchy_id_lock
);
1509 ida_destroy(&root
->cgroup_ida
);
1513 static int cgroup_set_super(struct super_block
*sb
, void *data
)
1516 struct cgroup_sb_opts
*opts
= data
;
1518 /* If we don't have a new root, we can't set up a new sb */
1519 if (!opts
->new_root
)
1522 BUG_ON(!opts
->subsys_mask
&& !opts
->none
);
1524 ret
= set_anon_super(sb
, NULL
);
1528 sb
->s_fs_info
= opts
->new_root
;
1529 opts
->new_root
->sb
= sb
;
1531 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
1532 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
1533 sb
->s_magic
= CGROUP_SUPER_MAGIC
;
1534 sb
->s_op
= &cgroup_ops
;
1539 static int cgroup_get_rootdir(struct super_block
*sb
)
1541 static const struct dentry_operations cgroup_dops
= {
1542 .d_iput
= cgroup_diput
,
1543 .d_delete
= cgroup_delete
,
1546 struct inode
*inode
=
1547 cgroup_new_inode(S_IFDIR
| S_IRUGO
| S_IXUGO
| S_IWUSR
, sb
);
1552 inode
->i_fop
= &simple_dir_operations
;
1553 inode
->i_op
= &cgroup_dir_inode_operations
;
1554 /* directories start off with i_nlink == 2 (for "." entry) */
1556 sb
->s_root
= d_make_root(inode
);
1559 /* for everything else we want ->d_op set */
1560 sb
->s_d_op
= &cgroup_dops
;
1564 static struct dentry
*cgroup_mount(struct file_system_type
*fs_type
,
1565 int flags
, const char *unused_dev_name
,
1568 struct cgroup_sb_opts opts
;
1569 struct cgroupfs_root
*root
;
1571 struct super_block
*sb
;
1572 struct cgroupfs_root
*new_root
;
1573 struct inode
*inode
;
1575 /* First find the desired set of subsystems */
1576 mutex_lock(&cgroup_mutex
);
1577 ret
= parse_cgroupfs_options(data
, &opts
);
1578 mutex_unlock(&cgroup_mutex
);
1583 * Allocate a new cgroup root. We may not need it if we're
1584 * reusing an existing hierarchy.
1586 new_root
= cgroup_root_from_opts(&opts
);
1587 if (IS_ERR(new_root
)) {
1588 ret
= PTR_ERR(new_root
);
1591 opts
.new_root
= new_root
;
1593 /* Locate an existing or new sb for this hierarchy */
1594 sb
= sget(fs_type
, cgroup_test_super
, cgroup_set_super
, 0, &opts
);
1597 cgroup_drop_root(opts
.new_root
);
1601 root
= sb
->s_fs_info
;
1603 if (root
== opts
.new_root
) {
1604 /* We used the new root structure, so this is a new hierarchy */
1605 struct list_head tmp_cg_links
;
1606 struct cgroup
*root_cgrp
= &root
->top_cgroup
;
1607 struct cgroupfs_root
*existing_root
;
1608 const struct cred
*cred
;
1612 BUG_ON(sb
->s_root
!= NULL
);
1614 ret
= cgroup_get_rootdir(sb
);
1616 goto drop_new_super
;
1617 inode
= sb
->s_root
->d_inode
;
1619 mutex_lock(&inode
->i_mutex
);
1620 mutex_lock(&cgroup_mutex
);
1621 mutex_lock(&cgroup_root_mutex
);
1623 /* Check for name clashes with existing mounts */
1625 if (strlen(root
->name
))
1626 for_each_active_root(existing_root
)
1627 if (!strcmp(existing_root
->name
, root
->name
))
1631 * We're accessing css_set_count without locking
1632 * css_set_lock here, but that's OK - it can only be
1633 * increased by someone holding cgroup_lock, and
1634 * that's us. The worst that can happen is that we
1635 * have some link structures left over
1637 ret
= allocate_cg_links(css_set_count
, &tmp_cg_links
);
1641 ret
= rebind_subsystems(root
, root
->subsys_mask
);
1642 if (ret
== -EBUSY
) {
1643 free_cg_links(&tmp_cg_links
);
1647 * There must be no failure case after here, since rebinding
1648 * takes care of subsystems' refcounts, which are explicitly
1649 * dropped in the failure exit path.
1652 /* EBUSY should be the only error here */
1655 list_add(&root
->root_list
, &roots
);
1658 sb
->s_root
->d_fsdata
= root_cgrp
;
1659 root
->top_cgroup
.dentry
= sb
->s_root
;
1661 /* Link the top cgroup in this hierarchy into all
1662 * the css_set objects */
1663 write_lock(&css_set_lock
);
1664 hash_for_each(css_set_table
, i
, cg
, hlist
)
1665 link_css_set(&tmp_cg_links
, cg
, root_cgrp
);
1666 write_unlock(&css_set_lock
);
1668 free_cg_links(&tmp_cg_links
);
1670 BUG_ON(!list_empty(&root_cgrp
->children
));
1671 BUG_ON(root
->number_of_cgroups
!= 1);
1673 cred
= override_creds(&init_cred
);
1674 cgroup_populate_dir(root_cgrp
, true, root
->subsys_mask
);
1676 mutex_unlock(&cgroup_root_mutex
);
1677 mutex_unlock(&cgroup_mutex
);
1678 mutex_unlock(&inode
->i_mutex
);
1681 * We re-used an existing hierarchy - the new root (if
1682 * any) is not needed
1684 cgroup_drop_root(opts
.new_root
);
1686 if (((root
->flags
| opts
.flags
) & CGRP_ROOT_SANE_BEHAVIOR
) &&
1687 root
->flags
!= opts
.flags
) {
1688 pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
1690 goto drop_new_super
;
1693 /* no subsys rebinding, so refcounts don't change */
1694 drop_parsed_module_refcounts(opts
.subsys_mask
);
1697 kfree(opts
.release_agent
);
1699 return dget(sb
->s_root
);
1702 mutex_unlock(&cgroup_root_mutex
);
1703 mutex_unlock(&cgroup_mutex
);
1704 mutex_unlock(&inode
->i_mutex
);
1706 deactivate_locked_super(sb
);
1708 drop_parsed_module_refcounts(opts
.subsys_mask
);
1710 kfree(opts
.release_agent
);
1712 return ERR_PTR(ret
);
1715 static void cgroup_kill_sb(struct super_block
*sb
) {
1716 struct cgroupfs_root
*root
= sb
->s_fs_info
;
1717 struct cgroup
*cgrp
= &root
->top_cgroup
;
1719 struct cg_cgroup_link
*link
;
1720 struct cg_cgroup_link
*saved_link
;
1724 BUG_ON(root
->number_of_cgroups
!= 1);
1725 BUG_ON(!list_empty(&cgrp
->children
));
1727 mutex_lock(&cgroup_mutex
);
1728 mutex_lock(&cgroup_root_mutex
);
1730 /* Rebind all subsystems back to the default hierarchy */
1731 ret
= rebind_subsystems(root
, 0);
1732 /* Shouldn't be able to fail ... */
1736 * Release all the links from css_sets to this hierarchy's
1739 write_lock(&css_set_lock
);
1741 list_for_each_entry_safe(link
, saved_link
, &cgrp
->css_sets
,
1743 list_del(&link
->cg_link_list
);
1744 list_del(&link
->cgrp_link_list
);
1747 write_unlock(&css_set_lock
);
1749 if (!list_empty(&root
->root_list
)) {
1750 list_del(&root
->root_list
);
1754 mutex_unlock(&cgroup_root_mutex
);
1755 mutex_unlock(&cgroup_mutex
);
1757 simple_xattrs_free(&cgrp
->xattrs
);
1759 kill_litter_super(sb
);
1760 cgroup_drop_root(root
);
1763 static struct file_system_type cgroup_fs_type
= {
1765 .mount
= cgroup_mount
,
1766 .kill_sb
= cgroup_kill_sb
,
1769 static struct kobject
*cgroup_kobj
;
1772 * cgroup_path - generate the path of a cgroup
1773 * @cgrp: the cgroup in question
1774 * @buf: the buffer to write the path into
1775 * @buflen: the length of the buffer
1777 * Writes path of cgroup into buf. Returns 0 on success, -errno on error.
1779 * We can't generate cgroup path using dentry->d_name, as accessing
1780 * dentry->name must be protected by irq-unsafe dentry->d_lock or parent
1781 * inode's i_mutex, while on the other hand cgroup_path() can be called
1782 * with some irq-safe spinlocks held.
1784 int cgroup_path(const struct cgroup
*cgrp
, char *buf
, int buflen
)
1786 int ret
= -ENAMETOOLONG
;
1789 if (!cgrp
->parent
) {
1790 if (strlcpy(buf
, "/", buflen
) >= buflen
)
1791 return -ENAMETOOLONG
;
1795 start
= buf
+ buflen
- 1;
1800 const char *name
= cgroup_name(cgrp
);
1804 if ((start
-= len
) < buf
)
1806 memcpy(start
, name
, len
);
1812 cgrp
= cgrp
->parent
;
1813 } while (cgrp
->parent
);
1815 memmove(buf
, start
, buf
+ buflen
- start
);
1820 EXPORT_SYMBOL_GPL(cgroup_path
);
1823 * Control Group taskset
1825 struct task_and_cgroup
{
1826 struct task_struct
*task
;
1827 struct cgroup
*cgrp
;
1831 struct cgroup_taskset
{
1832 struct task_and_cgroup single
;
1833 struct flex_array
*tc_array
;
1836 struct cgroup
*cur_cgrp
;
1840 * cgroup_taskset_first - reset taskset and return the first task
1841 * @tset: taskset of interest
1843 * @tset iteration is initialized and the first task is returned.
1845 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
)
1847 if (tset
->tc_array
) {
1849 return cgroup_taskset_next(tset
);
1851 tset
->cur_cgrp
= tset
->single
.cgrp
;
1852 return tset
->single
.task
;
1855 EXPORT_SYMBOL_GPL(cgroup_taskset_first
);
1858 * cgroup_taskset_next - iterate to the next task in taskset
1859 * @tset: taskset of interest
1861 * Return the next task in @tset. Iteration must have been initialized
1862 * with cgroup_taskset_first().
1864 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
)
1866 struct task_and_cgroup
*tc
;
1868 if (!tset
->tc_array
|| tset
->idx
>= tset
->tc_array_len
)
1871 tc
= flex_array_get(tset
->tc_array
, tset
->idx
++);
1872 tset
->cur_cgrp
= tc
->cgrp
;
1875 EXPORT_SYMBOL_GPL(cgroup_taskset_next
);
1878 * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task
1879 * @tset: taskset of interest
1881 * Return the cgroup for the current (last returned) task of @tset. This
1882 * function must be preceded by either cgroup_taskset_first() or
1883 * cgroup_taskset_next().
1885 struct cgroup
*cgroup_taskset_cur_cgroup(struct cgroup_taskset
*tset
)
1887 return tset
->cur_cgrp
;
1889 EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup
);
1892 * cgroup_taskset_size - return the number of tasks in taskset
1893 * @tset: taskset of interest
1895 int cgroup_taskset_size(struct cgroup_taskset
*tset
)
1897 return tset
->tc_array
? tset
->tc_array_len
: 1;
1899 EXPORT_SYMBOL_GPL(cgroup_taskset_size
);
1903 * cgroup_task_migrate - move a task from one cgroup to another.
1905 * Must be called with cgroup_mutex and threadgroup locked.
1907 static void cgroup_task_migrate(struct cgroup
*oldcgrp
,
1908 struct task_struct
*tsk
, struct css_set
*newcg
)
1910 struct css_set
*oldcg
;
1913 * We are synchronized through threadgroup_lock() against PF_EXITING
1914 * setting such that we can't race against cgroup_exit() changing the
1915 * css_set to init_css_set and dropping the old one.
1917 WARN_ON_ONCE(tsk
->flags
& PF_EXITING
);
1918 oldcg
= tsk
->cgroups
;
1921 rcu_assign_pointer(tsk
->cgroups
, newcg
);
1924 /* Update the css_set linked lists if we're using them */
1925 write_lock(&css_set_lock
);
1926 if (!list_empty(&tsk
->cg_list
))
1927 list_move(&tsk
->cg_list
, &newcg
->tasks
);
1928 write_unlock(&css_set_lock
);
1931 * We just gained a reference on oldcg by taking it from the task. As
1932 * trading it for newcg is protected by cgroup_mutex, we're safe to drop
1933 * it here; it will be freed under RCU.
1935 set_bit(CGRP_RELEASABLE
, &oldcgrp
->flags
);
1940 * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
1941 * @cgrp: the cgroup to attach to
1942 * @tsk: the task or the leader of the threadgroup to be attached
1943 * @threadgroup: attach the whole threadgroup?
1945 * Call holding cgroup_mutex and the group_rwsem of the leader. Will take
1946 * task_lock of @tsk or each thread in the threadgroup individually in turn.
1948 static int cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
,
1951 int retval
, i
, group_size
;
1952 struct cgroup_subsys
*ss
, *failed_ss
= NULL
;
1953 struct cgroupfs_root
*root
= cgrp
->root
;
1954 /* threadgroup list cursor and array */
1955 struct task_struct
*leader
= tsk
;
1956 struct task_and_cgroup
*tc
;
1957 struct flex_array
*group
;
1958 struct cgroup_taskset tset
= { };
1961 * step 0: in order to do expensive, possibly blocking operations for
1962 * every thread, we cannot iterate the thread group list, since it needs
1963 * rcu or tasklist locked. instead, build an array of all threads in the
1964 * group - group_rwsem prevents new threads from appearing, and if
1965 * threads exit, this will just be an over-estimate.
1968 group_size
= get_nr_threads(tsk
);
1971 /* flex_array supports very large thread-groups better than kmalloc. */
1972 group
= flex_array_alloc(sizeof(*tc
), group_size
, GFP_KERNEL
);
1975 /* pre-allocate to guarantee space while iterating in rcu read-side. */
1976 retval
= flex_array_prealloc(group
, 0, group_size
, GFP_KERNEL
);
1978 goto out_free_group_list
;
1982 * Prevent freeing of tasks while we take a snapshot. Tasks that are
1983 * already PF_EXITING could be freed from underneath us unless we
1984 * take an rcu_read_lock.
1988 struct task_and_cgroup ent
;
1990 /* @tsk either already exited or can't exit until the end */
1991 if (tsk
->flags
& PF_EXITING
)
1994 /* as per above, nr_threads may decrease, but not increase. */
1995 BUG_ON(i
>= group_size
);
1997 ent
.cgrp
= task_cgroup_from_root(tsk
, root
);
1998 /* nothing to do if this task is already in the cgroup */
1999 if (ent
.cgrp
== cgrp
)
2002 * saying GFP_ATOMIC has no effect here because we did prealloc
2003 * earlier, but it's good form to communicate our expectations.
2005 retval
= flex_array_put(group
, i
, &ent
, GFP_ATOMIC
);
2006 BUG_ON(retval
!= 0);
2011 } while_each_thread(leader
, tsk
);
2013 /* remember the number of threads in the array for later. */
2015 tset
.tc_array
= group
;
2016 tset
.tc_array_len
= group_size
;
2018 /* methods shouldn't be called if no task is actually migrating */
2021 goto out_free_group_list
;
2024 * step 1: check that we can legitimately attach to the cgroup.
2026 for_each_subsys(root
, ss
) {
2027 if (ss
->can_attach
) {
2028 retval
= ss
->can_attach(cgrp
, &tset
);
2031 goto out_cancel_attach
;
2037 * step 2: make sure css_sets exist for all threads to be migrated.
2038 * we use find_css_set, which allocates a new one if necessary.
2040 for (i
= 0; i
< group_size
; i
++) {
2041 tc
= flex_array_get(group
, i
);
2042 tc
->cg
= find_css_set(tc
->task
->cgroups
, cgrp
);
2045 goto out_put_css_set_refs
;
2050 * step 3: now that we're guaranteed success wrt the css_sets,
2051 * proceed to move all tasks to the new cgroup. There are no
2052 * failure cases after here, so this is the commit point.
2054 for (i
= 0; i
< group_size
; i
++) {
2055 tc
= flex_array_get(group
, i
);
2056 cgroup_task_migrate(tc
->cgrp
, tc
->task
, tc
->cg
);
2058 /* nothing is sensitive to fork() after this point. */
2061 * step 4: do subsystem attach callbacks.
2063 for_each_subsys(root
, ss
) {
2065 ss
->attach(cgrp
, &tset
);
2069 * step 5: success! and cleanup
2072 out_put_css_set_refs
:
2074 for (i
= 0; i
< group_size
; i
++) {
2075 tc
= flex_array_get(group
, i
);
2078 put_css_set(tc
->cg
);
2083 for_each_subsys(root
, ss
) {
2084 if (ss
== failed_ss
)
2086 if (ss
->cancel_attach
)
2087 ss
->cancel_attach(cgrp
, &tset
);
2090 out_free_group_list
:
2091 flex_array_free(group
);
2096 * Find the task_struct of the task to attach by vpid and pass it along to the
2097 * function to attach either it or all tasks in its threadgroup. Will lock
2098 * cgroup_mutex and threadgroup; may take task_lock of task.
2100 static int attach_task_by_pid(struct cgroup
*cgrp
, u64 pid
, bool threadgroup
)
2102 struct task_struct
*tsk
;
2103 const struct cred
*cred
= current_cred(), *tcred
;
2106 if (!cgroup_lock_live_group(cgrp
))
2112 tsk
= find_task_by_vpid(pid
);
2116 goto out_unlock_cgroup
;
2119 * even if we're attaching all tasks in the thread group, we
2120 * only need to check permissions on one of them.
2122 tcred
= __task_cred(tsk
);
2123 if (!uid_eq(cred
->euid
, GLOBAL_ROOT_UID
) &&
2124 !uid_eq(cred
->euid
, tcred
->uid
) &&
2125 !uid_eq(cred
->euid
, tcred
->suid
)) {
2128 goto out_unlock_cgroup
;
2134 tsk
= tsk
->group_leader
;
2137 * Workqueue threads may acquire PF_THREAD_BOUND and become
2138 * trapped in a cpuset, or RT worker may be born in a cgroup
2139 * with no rt_runtime allocated. Just say no.
2141 if (tsk
== kthreadd_task
|| (tsk
->flags
& PF_THREAD_BOUND
)) {
2144 goto out_unlock_cgroup
;
2147 get_task_struct(tsk
);
2150 threadgroup_lock(tsk
);
2152 if (!thread_group_leader(tsk
)) {
2154 * a race with de_thread from another thread's exec()
2155 * may strip us of our leadership, if this happens,
2156 * there is no choice but to throw this task away and
2157 * try again; this is
2158 * "double-double-toil-and-trouble-check locking".
2160 threadgroup_unlock(tsk
);
2161 put_task_struct(tsk
);
2162 goto retry_find_task
;
2166 ret
= cgroup_attach_task(cgrp
, tsk
, threadgroup
);
2168 threadgroup_unlock(tsk
);
2170 put_task_struct(tsk
);
2172 mutex_unlock(&cgroup_mutex
);
2177 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
2178 * @from: attach to all cgroups of a given task
2179 * @tsk: the task to be attached
2181 int cgroup_attach_task_all(struct task_struct
*from
, struct task_struct
*tsk
)
2183 struct cgroupfs_root
*root
;
2186 mutex_lock(&cgroup_mutex
);
2187 for_each_active_root(root
) {
2188 struct cgroup
*from_cg
= task_cgroup_from_root(from
, root
);
2190 retval
= cgroup_attach_task(from_cg
, tsk
, false);
2194 mutex_unlock(&cgroup_mutex
);
2198 EXPORT_SYMBOL_GPL(cgroup_attach_task_all
);
2200 static int cgroup_tasks_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 pid
)
2202 return attach_task_by_pid(cgrp
, pid
, false);
2205 static int cgroup_procs_write(struct cgroup
*cgrp
, struct cftype
*cft
, u64 tgid
)
2207 return attach_task_by_pid(cgrp
, tgid
, true);
2210 static int cgroup_release_agent_write(struct cgroup
*cgrp
, struct cftype
*cft
,
2213 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
2214 if (strlen(buffer
) >= PATH_MAX
)
2216 if (!cgroup_lock_live_group(cgrp
))
2218 mutex_lock(&cgroup_root_mutex
);
2219 strcpy(cgrp
->root
->release_agent_path
, buffer
);
2220 mutex_unlock(&cgroup_root_mutex
);
2221 mutex_unlock(&cgroup_mutex
);
2225 static int cgroup_release_agent_show(struct cgroup
*cgrp
, struct cftype
*cft
,
2226 struct seq_file
*seq
)
2228 if (!cgroup_lock_live_group(cgrp
))
2230 seq_puts(seq
, cgrp
->root
->release_agent_path
);
2231 seq_putc(seq
, '\n');
2232 mutex_unlock(&cgroup_mutex
);
2236 static int cgroup_sane_behavior_show(struct cgroup
*cgrp
, struct cftype
*cft
,
2237 struct seq_file
*seq
)
2239 seq_printf(seq
, "%d\n", cgroup_sane_behavior(cgrp
));
2243 /* A buffer size big enough for numbers or short strings */
2244 #define CGROUP_LOCAL_BUFFER_SIZE 64
2246 static ssize_t
cgroup_write_X64(struct cgroup
*cgrp
, struct cftype
*cft
,
2248 const char __user
*userbuf
,
2249 size_t nbytes
, loff_t
*unused_ppos
)
2251 char buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
2257 if (nbytes
>= sizeof(buffer
))
2259 if (copy_from_user(buffer
, userbuf
, nbytes
))
2262 buffer
[nbytes
] = 0; /* nul-terminate */
2263 if (cft
->write_u64
) {
2264 u64 val
= simple_strtoull(strstrip(buffer
), &end
, 0);
2267 retval
= cft
->write_u64(cgrp
, cft
, val
);
2269 s64 val
= simple_strtoll(strstrip(buffer
), &end
, 0);
2272 retval
= cft
->write_s64(cgrp
, cft
, val
);
2279 static ssize_t
cgroup_write_string(struct cgroup
*cgrp
, struct cftype
*cft
,
2281 const char __user
*userbuf
,
2282 size_t nbytes
, loff_t
*unused_ppos
)
2284 char local_buffer
[CGROUP_LOCAL_BUFFER_SIZE
];
2286 size_t max_bytes
= cft
->max_write_len
;
2287 char *buffer
= local_buffer
;
2290 max_bytes
= sizeof(local_buffer
) - 1;
2291 if (nbytes
>= max_bytes
)
2293 /* Allocate a dynamic buffer if we need one */
2294 if (nbytes
>= sizeof(local_buffer
)) {
2295 buffer
= kmalloc(nbytes
+ 1, GFP_KERNEL
);
2299 if (nbytes
&& copy_from_user(buffer
, userbuf
, nbytes
)) {
2304 buffer
[nbytes
] = 0; /* nul-terminate */
2305 retval
= cft
->write_string(cgrp
, cft
, strstrip(buffer
));
2309 if (buffer
!= local_buffer
)
2314 static ssize_t
cgroup_file_write(struct file
*file
, const char __user
*buf
,
2315 size_t nbytes
, loff_t
*ppos
)
2317 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2318 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2320 if (cgroup_is_removed(cgrp
))
2323 return cft
->write(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2324 if (cft
->write_u64
|| cft
->write_s64
)
2325 return cgroup_write_X64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2326 if (cft
->write_string
)
2327 return cgroup_write_string(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2329 int ret
= cft
->trigger(cgrp
, (unsigned int)cft
->private);
2330 return ret
? ret
: nbytes
;
2335 static ssize_t
cgroup_read_u64(struct cgroup
*cgrp
, struct cftype
*cft
,
2337 char __user
*buf
, size_t nbytes
,
2340 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
2341 u64 val
= cft
->read_u64(cgrp
, cft
);
2342 int len
= sprintf(tmp
, "%llu\n", (unsigned long long) val
);
2344 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
2347 static ssize_t
cgroup_read_s64(struct cgroup
*cgrp
, struct cftype
*cft
,
2349 char __user
*buf
, size_t nbytes
,
2352 char tmp
[CGROUP_LOCAL_BUFFER_SIZE
];
2353 s64 val
= cft
->read_s64(cgrp
, cft
);
2354 int len
= sprintf(tmp
, "%lld\n", (long long) val
);
2356 return simple_read_from_buffer(buf
, nbytes
, ppos
, tmp
, len
);
2359 static ssize_t
cgroup_file_read(struct file
*file
, char __user
*buf
,
2360 size_t nbytes
, loff_t
*ppos
)
2362 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2363 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
2365 if (cgroup_is_removed(cgrp
))
2369 return cft
->read(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2371 return cgroup_read_u64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2373 return cgroup_read_s64(cgrp
, cft
, file
, buf
, nbytes
, ppos
);
2378 * seqfile ops/methods for returning structured data. Currently just
2379 * supports string->u64 maps, but can be extended in future.
2382 struct cgroup_seqfile_state
{
2384 struct cgroup
*cgroup
;
2387 static int cgroup_map_add(struct cgroup_map_cb
*cb
, const char *key
, u64 value
)
2389 struct seq_file
*sf
= cb
->state
;
2390 return seq_printf(sf
, "%s %llu\n", key
, (unsigned long long)value
);
2393 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
2395 struct cgroup_seqfile_state
*state
= m
->private;
2396 struct cftype
*cft
= state
->cft
;
2397 if (cft
->read_map
) {
2398 struct cgroup_map_cb cb
= {
2399 .fill
= cgroup_map_add
,
2402 return cft
->read_map(state
->cgroup
, cft
, &cb
);
2404 return cft
->read_seq_string(state
->cgroup
, cft
, m
);
2407 static int cgroup_seqfile_release(struct inode
*inode
, struct file
*file
)
2409 struct seq_file
*seq
= file
->private_data
;
2410 kfree(seq
->private);
2411 return single_release(inode
, file
);
2414 static const struct file_operations cgroup_seqfile_operations
= {
2416 .write
= cgroup_file_write
,
2417 .llseek
= seq_lseek
,
2418 .release
= cgroup_seqfile_release
,
2421 static int cgroup_file_open(struct inode
*inode
, struct file
*file
)
2426 err
= generic_file_open(inode
, file
);
2429 cft
= __d_cft(file
->f_dentry
);
2431 if (cft
->read_map
|| cft
->read_seq_string
) {
2432 struct cgroup_seqfile_state
*state
=
2433 kzalloc(sizeof(*state
), GFP_USER
);
2437 state
->cgroup
= __d_cgrp(file
->f_dentry
->d_parent
);
2438 file
->f_op
= &cgroup_seqfile_operations
;
2439 err
= single_open(file
, cgroup_seqfile_show
, state
);
2442 } else if (cft
->open
)
2443 err
= cft
->open(inode
, file
);
2450 static int cgroup_file_release(struct inode
*inode
, struct file
*file
)
2452 struct cftype
*cft
= __d_cft(file
->f_dentry
);
2454 return cft
->release(inode
, file
);
2459 * cgroup_rename - Only allow simple rename of directories in place.
2461 static int cgroup_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2462 struct inode
*new_dir
, struct dentry
*new_dentry
)
2465 struct cgroup_name
*name
, *old_name
;
2466 struct cgroup
*cgrp
;
2469 * It's convinient to use parent dir's i_mutex to protected
2472 lockdep_assert_held(&old_dir
->i_mutex
);
2474 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
))
2476 if (new_dentry
->d_inode
)
2478 if (old_dir
!= new_dir
)
2481 cgrp
= __d_cgrp(old_dentry
);
2483 name
= cgroup_alloc_name(new_dentry
);
2487 ret
= simple_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2493 old_name
= cgrp
->name
;
2494 rcu_assign_pointer(cgrp
->name
, name
);
2496 kfree_rcu(old_name
, rcu_head
);
2500 static struct simple_xattrs
*__d_xattrs(struct dentry
*dentry
)
2502 if (S_ISDIR(dentry
->d_inode
->i_mode
))
2503 return &__d_cgrp(dentry
)->xattrs
;
2505 return &__d_cft(dentry
)->xattrs
;
2508 static inline int xattr_enabled(struct dentry
*dentry
)
2510 struct cgroupfs_root
*root
= dentry
->d_sb
->s_fs_info
;
2511 return root
->flags
& CGRP_ROOT_XATTR
;
2514 static bool is_valid_xattr(const char *name
)
2516 if (!strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
) ||
2517 !strncmp(name
, XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
))
2522 static int cgroup_setxattr(struct dentry
*dentry
, const char *name
,
2523 const void *val
, size_t size
, int flags
)
2525 if (!xattr_enabled(dentry
))
2527 if (!is_valid_xattr(name
))
2529 return simple_xattr_set(__d_xattrs(dentry
), name
, val
, size
, flags
);
2532 static int cgroup_removexattr(struct dentry
*dentry
, const char *name
)
2534 if (!xattr_enabled(dentry
))
2536 if (!is_valid_xattr(name
))
2538 return simple_xattr_remove(__d_xattrs(dentry
), name
);
2541 static ssize_t
cgroup_getxattr(struct dentry
*dentry
, const char *name
,
2542 void *buf
, size_t size
)
2544 if (!xattr_enabled(dentry
))
2546 if (!is_valid_xattr(name
))
2548 return simple_xattr_get(__d_xattrs(dentry
), name
, buf
, size
);
2551 static ssize_t
cgroup_listxattr(struct dentry
*dentry
, char *buf
, size_t size
)
2553 if (!xattr_enabled(dentry
))
2555 return simple_xattr_list(__d_xattrs(dentry
), buf
, size
);
2558 static const struct file_operations cgroup_file_operations
= {
2559 .read
= cgroup_file_read
,
2560 .write
= cgroup_file_write
,
2561 .llseek
= generic_file_llseek
,
2562 .open
= cgroup_file_open
,
2563 .release
= cgroup_file_release
,
2566 static const struct inode_operations cgroup_file_inode_operations
= {
2567 .setxattr
= cgroup_setxattr
,
2568 .getxattr
= cgroup_getxattr
,
2569 .listxattr
= cgroup_listxattr
,
2570 .removexattr
= cgroup_removexattr
,
2573 static const struct inode_operations cgroup_dir_inode_operations
= {
2574 .lookup
= cgroup_lookup
,
2575 .mkdir
= cgroup_mkdir
,
2576 .rmdir
= cgroup_rmdir
,
2577 .rename
= cgroup_rename
,
2578 .setxattr
= cgroup_setxattr
,
2579 .getxattr
= cgroup_getxattr
,
2580 .listxattr
= cgroup_listxattr
,
2581 .removexattr
= cgroup_removexattr
,
2584 static struct dentry
*cgroup_lookup(struct inode
*dir
, struct dentry
*dentry
, unsigned int flags
)
2586 if (dentry
->d_name
.len
> NAME_MAX
)
2587 return ERR_PTR(-ENAMETOOLONG
);
2588 d_add(dentry
, NULL
);
2593 * Check if a file is a control file
2595 static inline struct cftype
*__file_cft(struct file
*file
)
2597 if (file_inode(file
)->i_fop
!= &cgroup_file_operations
)
2598 return ERR_PTR(-EINVAL
);
2599 return __d_cft(file
->f_dentry
);
2602 static int cgroup_create_file(struct dentry
*dentry
, umode_t mode
,
2603 struct super_block
*sb
)
2605 struct inode
*inode
;
2609 if (dentry
->d_inode
)
2612 inode
= cgroup_new_inode(mode
, sb
);
2616 if (S_ISDIR(mode
)) {
2617 inode
->i_op
= &cgroup_dir_inode_operations
;
2618 inode
->i_fop
= &simple_dir_operations
;
2620 /* start off with i_nlink == 2 (for "." entry) */
2622 inc_nlink(dentry
->d_parent
->d_inode
);
2625 * Control reaches here with cgroup_mutex held.
2626 * @inode->i_mutex should nest outside cgroup_mutex but we
2627 * want to populate it immediately without releasing
2628 * cgroup_mutex. As @inode isn't visible to anyone else
2629 * yet, trylock will always succeed without affecting
2632 WARN_ON_ONCE(!mutex_trylock(&inode
->i_mutex
));
2633 } else if (S_ISREG(mode
)) {
2635 inode
->i_fop
= &cgroup_file_operations
;
2636 inode
->i_op
= &cgroup_file_inode_operations
;
2638 d_instantiate(dentry
, inode
);
2639 dget(dentry
); /* Extra count - pin the dentry in core */
2644 * cgroup_file_mode - deduce file mode of a control file
2645 * @cft: the control file in question
2647 * returns cft->mode if ->mode is not 0
2648 * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
2649 * returns S_IRUGO if it has only a read handler
2650 * returns S_IWUSR if it has only a write hander
2652 static umode_t
cgroup_file_mode(const struct cftype
*cft
)
2659 if (cft
->read
|| cft
->read_u64
|| cft
->read_s64
||
2660 cft
->read_map
|| cft
->read_seq_string
)
2663 if (cft
->write
|| cft
->write_u64
|| cft
->write_s64
||
2664 cft
->write_string
|| cft
->trigger
)
2670 static int cgroup_add_file(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
2673 struct dentry
*dir
= cgrp
->dentry
;
2674 struct cgroup
*parent
= __d_cgrp(dir
);
2675 struct dentry
*dentry
;
2679 char name
[MAX_CGROUP_TYPE_NAMELEN
+ MAX_CFTYPE_NAME
+ 2] = { 0 };
2681 simple_xattrs_init(&cft
->xattrs
);
2683 if (subsys
&& !(cgrp
->root
->flags
& CGRP_ROOT_NOPREFIX
)) {
2684 strcpy(name
, subsys
->name
);
2687 strcat(name
, cft
->name
);
2689 BUG_ON(!mutex_is_locked(&dir
->d_inode
->i_mutex
));
2691 cfe
= kzalloc(sizeof(*cfe
), GFP_KERNEL
);
2695 dentry
= lookup_one_len(name
, dir
, strlen(name
));
2696 if (IS_ERR(dentry
)) {
2697 error
= PTR_ERR(dentry
);
2701 mode
= cgroup_file_mode(cft
);
2702 error
= cgroup_create_file(dentry
, mode
| S_IFREG
, cgrp
->root
->sb
);
2704 cfe
->type
= (void *)cft
;
2705 cfe
->dentry
= dentry
;
2706 dentry
->d_fsdata
= cfe
;
2707 list_add_tail(&cfe
->node
, &parent
->files
);
2716 static int cgroup_addrm_files(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
2717 struct cftype cfts
[], bool is_add
)
2722 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
2723 /* does cft->flags tell us to skip this file on @cgrp? */
2724 if ((cft
->flags
& CFTYPE_INSANE
) && cgroup_sane_behavior(cgrp
))
2726 if ((cft
->flags
& CFTYPE_NOT_ON_ROOT
) && !cgrp
->parent
)
2728 if ((cft
->flags
& CFTYPE_ONLY_ON_ROOT
) && cgrp
->parent
)
2732 err
= cgroup_add_file(cgrp
, subsys
, cft
);
2734 pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
2738 cgroup_rm_file(cgrp
, cft
);
2744 static DEFINE_MUTEX(cgroup_cft_mutex
);
2746 static void cgroup_cfts_prepare(void)
2747 __acquires(&cgroup_cft_mutex
) __acquires(&cgroup_mutex
)
2750 * Thanks to the entanglement with vfs inode locking, we can't walk
2751 * the existing cgroups under cgroup_mutex and create files.
2752 * Instead, we increment reference on all cgroups and build list of
2753 * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure
2754 * exclusive access to the field.
2756 mutex_lock(&cgroup_cft_mutex
);
2757 mutex_lock(&cgroup_mutex
);
2760 static void cgroup_cfts_commit(struct cgroup_subsys
*ss
,
2761 struct cftype
*cfts
, bool is_add
)
2762 __releases(&cgroup_mutex
) __releases(&cgroup_cft_mutex
)
2765 struct cgroup
*cgrp
, *n
;
2767 /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
2768 if (cfts
&& ss
->root
!= &rootnode
) {
2769 list_for_each_entry(cgrp
, &ss
->root
->allcg_list
, allcg_node
) {
2771 list_add_tail(&cgrp
->cft_q_node
, &pending
);
2775 mutex_unlock(&cgroup_mutex
);
2778 * All new cgroups will see @cfts update on @ss->cftsets. Add/rm
2779 * files for all cgroups which were created before.
2781 list_for_each_entry_safe(cgrp
, n
, &pending
, cft_q_node
) {
2782 struct inode
*inode
= cgrp
->dentry
->d_inode
;
2784 mutex_lock(&inode
->i_mutex
);
2785 mutex_lock(&cgroup_mutex
);
2786 if (!cgroup_is_removed(cgrp
))
2787 cgroup_addrm_files(cgrp
, ss
, cfts
, is_add
);
2788 mutex_unlock(&cgroup_mutex
);
2789 mutex_unlock(&inode
->i_mutex
);
2791 list_del_init(&cgrp
->cft_q_node
);
2795 mutex_unlock(&cgroup_cft_mutex
);
2799 * cgroup_add_cftypes - add an array of cftypes to a subsystem
2800 * @ss: target cgroup subsystem
2801 * @cfts: zero-length name terminated array of cftypes
2803 * Register @cfts to @ss. Files described by @cfts are created for all
2804 * existing cgroups to which @ss is attached and all future cgroups will
2805 * have them too. This function can be called anytime whether @ss is
2808 * Returns 0 on successful registration, -errno on failure. Note that this
2809 * function currently returns 0 as long as @cfts registration is successful
2810 * even if some file creation attempts on existing cgroups fail.
2812 int cgroup_add_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2814 struct cftype_set
*set
;
2816 set
= kzalloc(sizeof(*set
), GFP_KERNEL
);
2820 cgroup_cfts_prepare();
2822 list_add_tail(&set
->node
, &ss
->cftsets
);
2823 cgroup_cfts_commit(ss
, cfts
, true);
2827 EXPORT_SYMBOL_GPL(cgroup_add_cftypes
);
2830 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
2831 * @ss: target cgroup subsystem
2832 * @cfts: zero-length name terminated array of cftypes
2834 * Unregister @cfts from @ss. Files described by @cfts are removed from
2835 * all existing cgroups to which @ss is attached and all future cgroups
2836 * won't have them either. This function can be called anytime whether @ss
2837 * is attached or not.
2839 * Returns 0 on successful unregistration, -ENOENT if @cfts is not
2840 * registered with @ss.
2842 int cgroup_rm_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2844 struct cftype_set
*set
;
2846 cgroup_cfts_prepare();
2848 list_for_each_entry(set
, &ss
->cftsets
, node
) {
2849 if (set
->cfts
== cfts
) {
2850 list_del_init(&set
->node
);
2851 cgroup_cfts_commit(ss
, cfts
, false);
2856 cgroup_cfts_commit(ss
, NULL
, false);
2861 * cgroup_task_count - count the number of tasks in a cgroup.
2862 * @cgrp: the cgroup in question
2864 * Return the number of tasks in the cgroup.
2866 int cgroup_task_count(const struct cgroup
*cgrp
)
2869 struct cg_cgroup_link
*link
;
2871 read_lock(&css_set_lock
);
2872 list_for_each_entry(link
, &cgrp
->css_sets
, cgrp_link_list
) {
2873 count
+= atomic_read(&link
->cg
->refcount
);
2875 read_unlock(&css_set_lock
);
2880 * Advance a list_head iterator. The iterator should be positioned at
2881 * the start of a css_set
2883 static void cgroup_advance_iter(struct cgroup
*cgrp
,
2884 struct cgroup_iter
*it
)
2886 struct list_head
*l
= it
->cg_link
;
2887 struct cg_cgroup_link
*link
;
2890 /* Advance to the next non-empty css_set */
2893 if (l
== &cgrp
->css_sets
) {
2897 link
= list_entry(l
, struct cg_cgroup_link
, cgrp_link_list
);
2899 } while (list_empty(&cg
->tasks
));
2901 it
->task
= cg
->tasks
.next
;
2905 * To reduce the fork() overhead for systems that are not actually
2906 * using their cgroups capability, we don't maintain the lists running
2907 * through each css_set to its tasks until we see the list actually
2908 * used - in other words after the first call to cgroup_iter_start().
2910 static void cgroup_enable_task_cg_lists(void)
2912 struct task_struct
*p
, *g
;
2913 write_lock(&css_set_lock
);
2914 use_task_css_set_links
= 1;
2916 * We need tasklist_lock because RCU is not safe against
2917 * while_each_thread(). Besides, a forking task that has passed
2918 * cgroup_post_fork() without seeing use_task_css_set_links = 1
2919 * is not guaranteed to have its child immediately visible in the
2920 * tasklist if we walk through it with RCU.
2922 read_lock(&tasklist_lock
);
2923 do_each_thread(g
, p
) {
2926 * We should check if the process is exiting, otherwise
2927 * it will race with cgroup_exit() in that the list
2928 * entry won't be deleted though the process has exited.
2930 if (!(p
->flags
& PF_EXITING
) && list_empty(&p
->cg_list
))
2931 list_add(&p
->cg_list
, &p
->cgroups
->tasks
);
2933 } while_each_thread(g
, p
);
2934 read_unlock(&tasklist_lock
);
2935 write_unlock(&css_set_lock
);
2939 * cgroup_next_descendant_pre - find the next descendant for pre-order walk
2940 * @pos: the current position (%NULL to initiate traversal)
2941 * @cgroup: cgroup whose descendants to walk
2943 * To be used by cgroup_for_each_descendant_pre(). Find the next
2944 * descendant to visit for pre-order traversal of @cgroup's descendants.
2946 struct cgroup
*cgroup_next_descendant_pre(struct cgroup
*pos
,
2947 struct cgroup
*cgroup
)
2949 struct cgroup
*next
;
2951 WARN_ON_ONCE(!rcu_read_lock_held());
2953 /* if first iteration, pretend we just visited @cgroup */
2955 if (list_empty(&cgroup
->children
))
2960 /* visit the first child if exists */
2961 next
= list_first_or_null_rcu(&pos
->children
, struct cgroup
, sibling
);
2965 /* no child, visit my or the closest ancestor's next sibling */
2967 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup
,
2969 if (&next
->sibling
!= &pos
->parent
->children
)
2973 } while (pos
!= cgroup
);
2977 EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre
);
2980 * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup
2981 * @pos: cgroup of interest
2983 * Return the rightmost descendant of @pos. If there's no descendant,
2984 * @pos is returned. This can be used during pre-order traversal to skip
2987 struct cgroup
*cgroup_rightmost_descendant(struct cgroup
*pos
)
2989 struct cgroup
*last
, *tmp
;
2991 WARN_ON_ONCE(!rcu_read_lock_held());
2995 /* ->prev isn't RCU safe, walk ->next till the end */
2997 list_for_each_entry_rcu(tmp
, &last
->children
, sibling
)
3003 EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant
);
3005 static struct cgroup
*cgroup_leftmost_descendant(struct cgroup
*pos
)
3007 struct cgroup
*last
;
3011 pos
= list_first_or_null_rcu(&pos
->children
, struct cgroup
,
3019 * cgroup_next_descendant_post - find the next descendant for post-order walk
3020 * @pos: the current position (%NULL to initiate traversal)
3021 * @cgroup: cgroup whose descendants to walk
3023 * To be used by cgroup_for_each_descendant_post(). Find the next
3024 * descendant to visit for post-order traversal of @cgroup's descendants.
3026 struct cgroup
*cgroup_next_descendant_post(struct cgroup
*pos
,
3027 struct cgroup
*cgroup
)
3029 struct cgroup
*next
;
3031 WARN_ON_ONCE(!rcu_read_lock_held());
3033 /* if first iteration, visit the leftmost descendant */
3035 next
= cgroup_leftmost_descendant(cgroup
);
3036 return next
!= cgroup
? next
: NULL
;
3039 /* if there's an unvisited sibling, visit its leftmost descendant */
3040 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup
, sibling
);
3041 if (&next
->sibling
!= &pos
->parent
->children
)
3042 return cgroup_leftmost_descendant(next
);
3044 /* no sibling left, visit parent */
3046 return next
!= cgroup
? next
: NULL
;
3048 EXPORT_SYMBOL_GPL(cgroup_next_descendant_post
);
3050 void cgroup_iter_start(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
3051 __acquires(css_set_lock
)
3054 * The first time anyone tries to iterate across a cgroup,
3055 * we need to enable the list linking each css_set to its
3056 * tasks, and fix up all existing tasks.
3058 if (!use_task_css_set_links
)
3059 cgroup_enable_task_cg_lists();
3061 read_lock(&css_set_lock
);
3062 it
->cg_link
= &cgrp
->css_sets
;
3063 cgroup_advance_iter(cgrp
, it
);
3066 struct task_struct
*cgroup_iter_next(struct cgroup
*cgrp
,
3067 struct cgroup_iter
*it
)
3069 struct task_struct
*res
;
3070 struct list_head
*l
= it
->task
;
3071 struct cg_cgroup_link
*link
;
3073 /* If the iterator cg is NULL, we have no tasks */
3076 res
= list_entry(l
, struct task_struct
, cg_list
);
3077 /* Advance iterator to find next entry */
3079 link
= list_entry(it
->cg_link
, struct cg_cgroup_link
, cgrp_link_list
);
3080 if (l
== &link
->cg
->tasks
) {
3081 /* We reached the end of this task list - move on to
3082 * the next cg_cgroup_link */
3083 cgroup_advance_iter(cgrp
, it
);
3090 void cgroup_iter_end(struct cgroup
*cgrp
, struct cgroup_iter
*it
)
3091 __releases(css_set_lock
)
3093 read_unlock(&css_set_lock
);
3096 static inline int started_after_time(struct task_struct
*t1
,
3097 struct timespec
*time
,
3098 struct task_struct
*t2
)
3100 int start_diff
= timespec_compare(&t1
->start_time
, time
);
3101 if (start_diff
> 0) {
3103 } else if (start_diff
< 0) {
3107 * Arbitrarily, if two processes started at the same
3108 * time, we'll say that the lower pointer value
3109 * started first. Note that t2 may have exited by now
3110 * so this may not be a valid pointer any longer, but
3111 * that's fine - it still serves to distinguish
3112 * between two tasks started (effectively) simultaneously.
3119 * This function is a callback from heap_insert() and is used to order
3121 * In this case we order the heap in descending task start time.
3123 static inline int started_after(void *p1
, void *p2
)
3125 struct task_struct
*t1
= p1
;
3126 struct task_struct
*t2
= p2
;
3127 return started_after_time(t1
, &t2
->start_time
, t2
);
3131 * cgroup_scan_tasks - iterate though all the tasks in a cgroup
3132 * @scan: struct cgroup_scanner containing arguments for the scan
3134 * Arguments include pointers to callback functions test_task() and
3136 * Iterate through all the tasks in a cgroup, calling test_task() for each,
3137 * and if it returns true, call process_task() for it also.
3138 * The test_task pointer may be NULL, meaning always true (select all tasks).
3139 * Effectively duplicates cgroup_iter_{start,next,end}()
3140 * but does not lock css_set_lock for the call to process_task().
3141 * The struct cgroup_scanner may be embedded in any structure of the caller's
3143 * It is guaranteed that process_task() will act on every task that
3144 * is a member of the cgroup for the duration of this call. This
3145 * function may or may not call process_task() for tasks that exit
3146 * or move to a different cgroup during the call, or are forked or
3147 * move into the cgroup during the call.
3149 * Note that test_task() may be called with locks held, and may in some
3150 * situations be called multiple times for the same task, so it should
3152 * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been
3153 * pre-allocated and will be used for heap operations (and its "gt" member will
3154 * be overwritten), else a temporary heap will be used (allocation of which
3155 * may cause this function to fail).
3157 int cgroup_scan_tasks(struct cgroup_scanner
*scan
)
3160 struct cgroup_iter it
;
3161 struct task_struct
*p
, *dropped
;
3162 /* Never dereference latest_task, since it's not refcounted */
3163 struct task_struct
*latest_task
= NULL
;
3164 struct ptr_heap tmp_heap
;
3165 struct ptr_heap
*heap
;
3166 struct timespec latest_time
= { 0, 0 };
3169 /* The caller supplied our heap and pre-allocated its memory */
3171 heap
->gt
= &started_after
;
3173 /* We need to allocate our own heap memory */
3175 retval
= heap_init(heap
, PAGE_SIZE
, GFP_KERNEL
, &started_after
);
3177 /* cannot allocate the heap */
3183 * Scan tasks in the cgroup, using the scanner's "test_task" callback
3184 * to determine which are of interest, and using the scanner's
3185 * "process_task" callback to process any of them that need an update.
3186 * Since we don't want to hold any locks during the task updates,
3187 * gather tasks to be processed in a heap structure.
3188 * The heap is sorted by descending task start time.
3189 * If the statically-sized heap fills up, we overflow tasks that
3190 * started later, and in future iterations only consider tasks that
3191 * started after the latest task in the previous pass. This
3192 * guarantees forward progress and that we don't miss any tasks.
3195 cgroup_iter_start(scan
->cg
, &it
);
3196 while ((p
= cgroup_iter_next(scan
->cg
, &it
))) {
3198 * Only affect tasks that qualify per the caller's callback,
3199 * if he provided one
3201 if (scan
->test_task
&& !scan
->test_task(p
, scan
))
3204 * Only process tasks that started after the last task
3207 if (!started_after_time(p
, &latest_time
, latest_task
))
3209 dropped
= heap_insert(heap
, p
);
3210 if (dropped
== NULL
) {
3212 * The new task was inserted; the heap wasn't
3216 } else if (dropped
!= p
) {
3218 * The new task was inserted, and pushed out a
3222 put_task_struct(dropped
);
3225 * Else the new task was newer than anything already in
3226 * the heap and wasn't inserted
3229 cgroup_iter_end(scan
->cg
, &it
);
3232 for (i
= 0; i
< heap
->size
; i
++) {
3233 struct task_struct
*q
= heap
->ptrs
[i
];
3235 latest_time
= q
->start_time
;
3238 /* Process the task per the caller's callback */
3239 scan
->process_task(q
, scan
);
3243 * If we had to process any tasks at all, scan again
3244 * in case some of them were in the middle of forking
3245 * children that didn't get processed.
3246 * Not the most efficient way to do it, but it avoids
3247 * having to take callback_mutex in the fork path
3251 if (heap
== &tmp_heap
)
3252 heap_free(&tmp_heap
);
3256 static void cgroup_transfer_one_task(struct task_struct
*task
,
3257 struct cgroup_scanner
*scan
)
3259 struct cgroup
*new_cgroup
= scan
->data
;
3261 mutex_lock(&cgroup_mutex
);
3262 cgroup_attach_task(new_cgroup
, task
, false);
3263 mutex_unlock(&cgroup_mutex
);
3267 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
3268 * @to: cgroup to which the tasks will be moved
3269 * @from: cgroup in which the tasks currently reside
3271 int cgroup_transfer_tasks(struct cgroup
*to
, struct cgroup
*from
)
3273 struct cgroup_scanner scan
;
3276 scan
.test_task
= NULL
; /* select all tasks in cgroup */
3277 scan
.process_task
= cgroup_transfer_one_task
;
3281 return cgroup_scan_tasks(&scan
);
3285 * Stuff for reading the 'tasks'/'procs' files.
3287 * Reading this file can return large amounts of data if a cgroup has
3288 * *lots* of attached tasks. So it may need several calls to read(),
3289 * but we cannot guarantee that the information we produce is correct
3290 * unless we produce it entirely atomically.
3294 /* which pidlist file are we talking about? */
3295 enum cgroup_filetype
{
3301 * A pidlist is a list of pids that virtually represents the contents of one
3302 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
3303 * a pair (one each for procs, tasks) for each pid namespace that's relevant
3306 struct cgroup_pidlist
{
3308 * used to find which pidlist is wanted. doesn't change as long as
3309 * this particular list stays in the list.
3311 struct { enum cgroup_filetype type
; struct pid_namespace
*ns
; } key
;
3314 /* how many elements the above list has */
3316 /* how many files are using the current array */
3318 /* each of these stored in a list by its cgroup */
3319 struct list_head links
;
3320 /* pointer to the cgroup we belong to, for list removal purposes */
3321 struct cgroup
*owner
;
3322 /* protects the other fields */
3323 struct rw_semaphore mutex
;
3327 * The following two functions "fix" the issue where there are more pids
3328 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
3329 * TODO: replace with a kernel-wide solution to this problem
3331 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
3332 static void *pidlist_allocate(int count
)
3334 if (PIDLIST_TOO_LARGE(count
))
3335 return vmalloc(count
* sizeof(pid_t
));
3337 return kmalloc(count
* sizeof(pid_t
), GFP_KERNEL
);
3339 static void pidlist_free(void *p
)
3341 if (is_vmalloc_addr(p
))
3348 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
3349 * Returns the number of unique elements.
3351 static int pidlist_uniq(pid_t
*list
, int length
)
3356 * we presume the 0th element is unique, so i starts at 1. trivial
3357 * edge cases first; no work needs to be done for either
3359 if (length
== 0 || length
== 1)
3361 /* src and dest walk down the list; dest counts unique elements */
3362 for (src
= 1; src
< length
; src
++) {
3363 /* find next unique element */
3364 while (list
[src
] == list
[src
-1]) {
3369 /* dest always points to where the next unique element goes */
3370 list
[dest
] = list
[src
];
3377 static int cmppid(const void *a
, const void *b
)
3379 return *(pid_t
*)a
- *(pid_t
*)b
;
3383 * find the appropriate pidlist for our purpose (given procs vs tasks)
3384 * returns with the lock on that pidlist already held, and takes care
3385 * of the use count, or returns NULL with no locks held if we're out of
3388 static struct cgroup_pidlist
*cgroup_pidlist_find(struct cgroup
*cgrp
,
3389 enum cgroup_filetype type
)
3391 struct cgroup_pidlist
*l
;
3392 /* don't need task_nsproxy() if we're looking at ourself */
3393 struct pid_namespace
*ns
= task_active_pid_ns(current
);
3396 * We can't drop the pidlist_mutex before taking the l->mutex in case
3397 * the last ref-holder is trying to remove l from the list at the same
3398 * time. Holding the pidlist_mutex precludes somebody taking whichever
3399 * list we find out from under us - compare release_pid_array().
3401 mutex_lock(&cgrp
->pidlist_mutex
);
3402 list_for_each_entry(l
, &cgrp
->pidlists
, links
) {
3403 if (l
->key
.type
== type
&& l
->key
.ns
== ns
) {
3404 /* make sure l doesn't vanish out from under us */
3405 down_write(&l
->mutex
);
3406 mutex_unlock(&cgrp
->pidlist_mutex
);
3410 /* entry not found; create a new one */
3411 l
= kmalloc(sizeof(struct cgroup_pidlist
), GFP_KERNEL
);
3413 mutex_unlock(&cgrp
->pidlist_mutex
);
3416 init_rwsem(&l
->mutex
);
3417 down_write(&l
->mutex
);
3419 l
->key
.ns
= get_pid_ns(ns
);
3420 l
->use_count
= 0; /* don't increment here */
3423 list_add(&l
->links
, &cgrp
->pidlists
);
3424 mutex_unlock(&cgrp
->pidlist_mutex
);
3429 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
3431 static int pidlist_array_load(struct cgroup
*cgrp
, enum cgroup_filetype type
,
3432 struct cgroup_pidlist
**lp
)
3436 int pid
, n
= 0; /* used for populating the array */
3437 struct cgroup_iter it
;
3438 struct task_struct
*tsk
;
3439 struct cgroup_pidlist
*l
;
3442 * If cgroup gets more users after we read count, we won't have
3443 * enough space - tough. This race is indistinguishable to the
3444 * caller from the case that the additional cgroup users didn't
3445 * show up until sometime later on.
3447 length
= cgroup_task_count(cgrp
);
3448 array
= pidlist_allocate(length
);
3451 /* now, populate the array */
3452 cgroup_iter_start(cgrp
, &it
);
3453 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
3454 if (unlikely(n
== length
))
3456 /* get tgid or pid for procs or tasks file respectively */
3457 if (type
== CGROUP_FILE_PROCS
)
3458 pid
= task_tgid_vnr(tsk
);
3460 pid
= task_pid_vnr(tsk
);
3461 if (pid
> 0) /* make sure to only use valid results */
3464 cgroup_iter_end(cgrp
, &it
);
3466 /* now sort & (if procs) strip out duplicates */
3467 sort(array
, length
, sizeof(pid_t
), cmppid
, NULL
);
3468 if (type
== CGROUP_FILE_PROCS
)
3469 length
= pidlist_uniq(array
, length
);
3470 l
= cgroup_pidlist_find(cgrp
, type
);
3472 pidlist_free(array
);
3475 /* store array, freeing old if necessary - lock already held */
3476 pidlist_free(l
->list
);
3480 up_write(&l
->mutex
);
3486 * cgroupstats_build - build and fill cgroupstats
3487 * @stats: cgroupstats to fill information into
3488 * @dentry: A dentry entry belonging to the cgroup for which stats have
3491 * Build and fill cgroupstats so that taskstats can export it to user
3494 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
3497 struct cgroup
*cgrp
;
3498 struct cgroup_iter it
;
3499 struct task_struct
*tsk
;
3502 * Validate dentry by checking the superblock operations,
3503 * and make sure it's a directory.
3505 if (dentry
->d_sb
->s_op
!= &cgroup_ops
||
3506 !S_ISDIR(dentry
->d_inode
->i_mode
))
3510 cgrp
= dentry
->d_fsdata
;
3512 cgroup_iter_start(cgrp
, &it
);
3513 while ((tsk
= cgroup_iter_next(cgrp
, &it
))) {
3514 switch (tsk
->state
) {
3516 stats
->nr_running
++;
3518 case TASK_INTERRUPTIBLE
:
3519 stats
->nr_sleeping
++;
3521 case TASK_UNINTERRUPTIBLE
:
3522 stats
->nr_uninterruptible
++;
3525 stats
->nr_stopped
++;
3528 if (delayacct_is_task_waiting_on_io(tsk
))
3529 stats
->nr_io_wait
++;
3533 cgroup_iter_end(cgrp
, &it
);
3541 * seq_file methods for the tasks/procs files. The seq_file position is the
3542 * next pid to display; the seq_file iterator is a pointer to the pid
3543 * in the cgroup->l->list array.
3546 static void *cgroup_pidlist_start(struct seq_file
*s
, loff_t
*pos
)
3549 * Initially we receive a position value that corresponds to
3550 * one more than the last pid shown (or 0 on the first call or
3551 * after a seek to the start). Use a binary-search to find the
3552 * next pid to display, if any
3554 struct cgroup_pidlist
*l
= s
->private;
3555 int index
= 0, pid
= *pos
;
3558 down_read(&l
->mutex
);
3560 int end
= l
->length
;
3562 while (index
< end
) {
3563 int mid
= (index
+ end
) / 2;
3564 if (l
->list
[mid
] == pid
) {
3567 } else if (l
->list
[mid
] <= pid
)
3573 /* If we're off the end of the array, we're done */
3574 if (index
>= l
->length
)
3576 /* Update the abstract position to be the actual pid that we found */
3577 iter
= l
->list
+ index
;
3582 static void cgroup_pidlist_stop(struct seq_file
*s
, void *v
)
3584 struct cgroup_pidlist
*l
= s
->private;
3588 static void *cgroup_pidlist_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
3590 struct cgroup_pidlist
*l
= s
->private;
3592 pid_t
*end
= l
->list
+ l
->length
;
3594 * Advance to the next pid in the array. If this goes off the
3606 static int cgroup_pidlist_show(struct seq_file
*s
, void *v
)
3608 return seq_printf(s
, "%d\n", *(int *)v
);
3612 * seq_operations functions for iterating on pidlists through seq_file -
3613 * independent of whether it's tasks or procs
3615 static const struct seq_operations cgroup_pidlist_seq_operations
= {
3616 .start
= cgroup_pidlist_start
,
3617 .stop
= cgroup_pidlist_stop
,
3618 .next
= cgroup_pidlist_next
,
3619 .show
= cgroup_pidlist_show
,
3622 static void cgroup_release_pid_array(struct cgroup_pidlist
*l
)
3625 * the case where we're the last user of this particular pidlist will
3626 * have us remove it from the cgroup's list, which entails taking the
3627 * mutex. since in pidlist_find the pidlist->lock depends on cgroup->
3628 * pidlist_mutex, we have to take pidlist_mutex first.
3630 mutex_lock(&l
->owner
->pidlist_mutex
);
3631 down_write(&l
->mutex
);
3632 BUG_ON(!l
->use_count
);
3633 if (!--l
->use_count
) {
3634 /* we're the last user if refcount is 0; remove and free */
3635 list_del(&l
->links
);
3636 mutex_unlock(&l
->owner
->pidlist_mutex
);
3637 pidlist_free(l
->list
);
3638 put_pid_ns(l
->key
.ns
);
3639 up_write(&l
->mutex
);
3643 mutex_unlock(&l
->owner
->pidlist_mutex
);
3644 up_write(&l
->mutex
);
3647 static int cgroup_pidlist_release(struct inode
*inode
, struct file
*file
)
3649 struct cgroup_pidlist
*l
;
3650 if (!(file
->f_mode
& FMODE_READ
))
3653 * the seq_file will only be initialized if the file was opened for
3654 * reading; hence we check if it's not null only in that case.
3656 l
= ((struct seq_file
*)file
->private_data
)->private;
3657 cgroup_release_pid_array(l
);
3658 return seq_release(inode
, file
);
3661 static const struct file_operations cgroup_pidlist_operations
= {
3663 .llseek
= seq_lseek
,
3664 .write
= cgroup_file_write
,
3665 .release
= cgroup_pidlist_release
,
3669 * The following functions handle opens on a file that displays a pidlist
3670 * (tasks or procs). Prepare an array of the process/thread IDs of whoever's
3673 /* helper function for the two below it */
3674 static int cgroup_pidlist_open(struct file
*file
, enum cgroup_filetype type
)
3676 struct cgroup
*cgrp
= __d_cgrp(file
->f_dentry
->d_parent
);
3677 struct cgroup_pidlist
*l
;
3680 /* Nothing to do for write-only files */
3681 if (!(file
->f_mode
& FMODE_READ
))
3684 /* have the array populated */
3685 retval
= pidlist_array_load(cgrp
, type
, &l
);
3688 /* configure file information */
3689 file
->f_op
= &cgroup_pidlist_operations
;
3691 retval
= seq_open(file
, &cgroup_pidlist_seq_operations
);
3693 cgroup_release_pid_array(l
);
3696 ((struct seq_file
*)file
->private_data
)->private = l
;
3699 static int cgroup_tasks_open(struct inode
*unused
, struct file
*file
)
3701 return cgroup_pidlist_open(file
, CGROUP_FILE_TASKS
);
3703 static int cgroup_procs_open(struct inode
*unused
, struct file
*file
)
3705 return cgroup_pidlist_open(file
, CGROUP_FILE_PROCS
);
3708 static u64
cgroup_read_notify_on_release(struct cgroup
*cgrp
,
3711 return notify_on_release(cgrp
);
3714 static int cgroup_write_notify_on_release(struct cgroup
*cgrp
,
3718 clear_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
3720 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3722 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3727 * Unregister event and free resources.
3729 * Gets called from workqueue.
3731 static void cgroup_event_remove(struct work_struct
*work
)
3733 struct cgroup_event
*event
= container_of(work
, struct cgroup_event
,
3735 struct cgroup
*cgrp
= event
->cgrp
;
3737 remove_wait_queue(event
->wqh
, &event
->wait
);
3739 event
->cft
->unregister_event(cgrp
, event
->cft
, event
->eventfd
);
3741 /* Notify userspace the event is going away. */
3742 eventfd_signal(event
->eventfd
, 1);
3744 eventfd_ctx_put(event
->eventfd
);
3750 * Gets called on POLLHUP on eventfd when user closes it.
3752 * Called with wqh->lock held and interrupts disabled.
3754 static int cgroup_event_wake(wait_queue_t
*wait
, unsigned mode
,
3755 int sync
, void *key
)
3757 struct cgroup_event
*event
= container_of(wait
,
3758 struct cgroup_event
, wait
);
3759 struct cgroup
*cgrp
= event
->cgrp
;
3760 unsigned long flags
= (unsigned long)key
;
3762 if (flags
& POLLHUP
) {
3764 * If the event has been detached at cgroup removal, we
3765 * can simply return knowing the other side will cleanup
3768 * We can't race against event freeing since the other
3769 * side will require wqh->lock via remove_wait_queue(),
3772 spin_lock(&cgrp
->event_list_lock
);
3773 if (!list_empty(&event
->list
)) {
3774 list_del_init(&event
->list
);
3776 * We are in atomic context, but cgroup_event_remove()
3777 * may sleep, so we have to call it in workqueue.
3779 schedule_work(&event
->remove
);
3781 spin_unlock(&cgrp
->event_list_lock
);
3787 static void cgroup_event_ptable_queue_proc(struct file
*file
,
3788 wait_queue_head_t
*wqh
, poll_table
*pt
)
3790 struct cgroup_event
*event
= container_of(pt
,
3791 struct cgroup_event
, pt
);
3794 add_wait_queue(wqh
, &event
->wait
);
3798 * Parse input and register new cgroup event handler.
3800 * Input must be in format '<event_fd> <control_fd> <args>'.
3801 * Interpretation of args is defined by control file implementation.
3803 static int cgroup_write_event_control(struct cgroup
*cgrp
, struct cftype
*cft
,
3806 struct cgroup_event
*event
= NULL
;
3807 struct cgroup
*cgrp_cfile
;
3808 unsigned int efd
, cfd
;
3809 struct file
*efile
= NULL
;
3810 struct file
*cfile
= NULL
;
3814 efd
= simple_strtoul(buffer
, &endp
, 10);
3819 cfd
= simple_strtoul(buffer
, &endp
, 10);
3820 if ((*endp
!= ' ') && (*endp
!= '\0'))
3824 event
= kzalloc(sizeof(*event
), GFP_KERNEL
);
3828 INIT_LIST_HEAD(&event
->list
);
3829 init_poll_funcptr(&event
->pt
, cgroup_event_ptable_queue_proc
);
3830 init_waitqueue_func_entry(&event
->wait
, cgroup_event_wake
);
3831 INIT_WORK(&event
->remove
, cgroup_event_remove
);
3833 efile
= eventfd_fget(efd
);
3834 if (IS_ERR(efile
)) {
3835 ret
= PTR_ERR(efile
);
3839 event
->eventfd
= eventfd_ctx_fileget(efile
);
3840 if (IS_ERR(event
->eventfd
)) {
3841 ret
= PTR_ERR(event
->eventfd
);
3851 /* the process need read permission on control file */
3852 /* AV: shouldn't we check that it's been opened for read instead? */
3853 ret
= inode_permission(file_inode(cfile
), MAY_READ
);
3857 event
->cft
= __file_cft(cfile
);
3858 if (IS_ERR(event
->cft
)) {
3859 ret
= PTR_ERR(event
->cft
);
3864 * The file to be monitored must be in the same cgroup as
3865 * cgroup.event_control is.
3867 cgrp_cfile
= __d_cgrp(cfile
->f_dentry
->d_parent
);
3868 if (cgrp_cfile
!= cgrp
) {
3873 if (!event
->cft
->register_event
|| !event
->cft
->unregister_event
) {
3878 ret
= event
->cft
->register_event(cgrp
, event
->cft
,
3879 event
->eventfd
, buffer
);
3884 * Events should be removed after rmdir of cgroup directory, but before
3885 * destroying subsystem state objects. Let's take reference to cgroup
3886 * directory dentry to do that.
3890 spin_lock(&cgrp
->event_list_lock
);
3891 list_add(&event
->list
, &cgrp
->event_list
);
3892 spin_unlock(&cgrp
->event_list_lock
);
3903 if (event
&& event
->eventfd
&& !IS_ERR(event
->eventfd
))
3904 eventfd_ctx_put(event
->eventfd
);
3906 if (!IS_ERR_OR_NULL(efile
))
3914 static u64
cgroup_clone_children_read(struct cgroup
*cgrp
,
3917 return test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
3920 static int cgroup_clone_children_write(struct cgroup
*cgrp
,
3925 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
3927 clear_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
3932 * for the common functions, 'private' gives the type of file
3934 /* for hysterical raisins, we can't put this on the older files */
3935 #define CGROUP_FILE_GENERIC_PREFIX "cgroup."
3936 static struct cftype files
[] = {
3939 .open
= cgroup_tasks_open
,
3940 .write_u64
= cgroup_tasks_write
,
3941 .release
= cgroup_pidlist_release
,
3942 .mode
= S_IRUGO
| S_IWUSR
,
3945 .name
= CGROUP_FILE_GENERIC_PREFIX
"procs",
3946 .open
= cgroup_procs_open
,
3947 .write_u64
= cgroup_procs_write
,
3948 .release
= cgroup_pidlist_release
,
3949 .mode
= S_IRUGO
| S_IWUSR
,
3952 .name
= "notify_on_release",
3953 .read_u64
= cgroup_read_notify_on_release
,
3954 .write_u64
= cgroup_write_notify_on_release
,
3957 .name
= CGROUP_FILE_GENERIC_PREFIX
"event_control",
3958 .write_string
= cgroup_write_event_control
,
3962 .name
= "cgroup.clone_children",
3963 .flags
= CFTYPE_INSANE
,
3964 .read_u64
= cgroup_clone_children_read
,
3965 .write_u64
= cgroup_clone_children_write
,
3968 .name
= "cgroup.sane_behavior",
3969 .flags
= CFTYPE_ONLY_ON_ROOT
,
3970 .read_seq_string
= cgroup_sane_behavior_show
,
3973 .name
= "release_agent",
3974 .flags
= CFTYPE_ONLY_ON_ROOT
,
3975 .read_seq_string
= cgroup_release_agent_show
,
3976 .write_string
= cgroup_release_agent_write
,
3977 .max_write_len
= PATH_MAX
,
3983 * cgroup_populate_dir - selectively creation of files in a directory
3984 * @cgrp: target cgroup
3985 * @base_files: true if the base files should be added
3986 * @subsys_mask: mask of the subsystem ids whose files should be added
3988 static int cgroup_populate_dir(struct cgroup
*cgrp
, bool base_files
,
3989 unsigned long subsys_mask
)
3992 struct cgroup_subsys
*ss
;
3995 err
= cgroup_addrm_files(cgrp
, NULL
, files
, true);
4000 /* process cftsets of each subsystem */
4001 for_each_subsys(cgrp
->root
, ss
) {
4002 struct cftype_set
*set
;
4003 if (!test_bit(ss
->subsys_id
, &subsys_mask
))
4006 list_for_each_entry(set
, &ss
->cftsets
, node
)
4007 cgroup_addrm_files(cgrp
, ss
, set
->cfts
, true);
4010 /* This cgroup is ready now */
4011 for_each_subsys(cgrp
->root
, ss
) {
4012 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4014 * Update id->css pointer and make this css visible from
4015 * CSS ID functions. This pointer will be dereferened
4016 * from RCU-read-side without locks.
4019 rcu_assign_pointer(css
->id
->css
, css
);
4025 static void css_dput_fn(struct work_struct
*work
)
4027 struct cgroup_subsys_state
*css
=
4028 container_of(work
, struct cgroup_subsys_state
, dput_work
);
4029 struct dentry
*dentry
= css
->cgroup
->dentry
;
4030 struct super_block
*sb
= dentry
->d_sb
;
4032 atomic_inc(&sb
->s_active
);
4034 deactivate_super(sb
);
4037 static void init_cgroup_css(struct cgroup_subsys_state
*css
,
4038 struct cgroup_subsys
*ss
,
4039 struct cgroup
*cgrp
)
4042 atomic_set(&css
->refcnt
, 1);
4045 if (cgrp
== dummytop
)
4046 css
->flags
|= CSS_ROOT
;
4047 BUG_ON(cgrp
->subsys
[ss
->subsys_id
]);
4048 cgrp
->subsys
[ss
->subsys_id
] = css
;
4051 * css holds an extra ref to @cgrp->dentry which is put on the last
4052 * css_put(). dput() requires process context, which css_put() may
4053 * be called without. @css->dput_work will be used to invoke
4054 * dput() asynchronously from css_put().
4056 INIT_WORK(&css
->dput_work
, css_dput_fn
);
4059 /* invoke ->post_create() on a new CSS and mark it online if successful */
4060 static int online_css(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4064 lockdep_assert_held(&cgroup_mutex
);
4067 ret
= ss
->css_online(cgrp
);
4069 cgrp
->subsys
[ss
->subsys_id
]->flags
|= CSS_ONLINE
;
4073 /* if the CSS is online, invoke ->pre_destory() on it and mark it offline */
4074 static void offline_css(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4075 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
4077 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4079 lockdep_assert_held(&cgroup_mutex
);
4081 if (!(css
->flags
& CSS_ONLINE
))
4084 if (ss
->css_offline
)
4085 ss
->css_offline(cgrp
);
4087 cgrp
->subsys
[ss
->subsys_id
]->flags
&= ~CSS_ONLINE
;
4091 * cgroup_create - create a cgroup
4092 * @parent: cgroup that will be parent of the new cgroup
4093 * @dentry: dentry of the new cgroup
4094 * @mode: mode to set on new inode
4096 * Must be called with the mutex on the parent inode held
4098 static long cgroup_create(struct cgroup
*parent
, struct dentry
*dentry
,
4101 struct cgroup
*cgrp
;
4102 struct cgroup_name
*name
;
4103 struct cgroupfs_root
*root
= parent
->root
;
4105 struct cgroup_subsys
*ss
;
4106 struct super_block
*sb
= root
->sb
;
4108 /* allocate the cgroup and its ID, 0 is reserved for the root */
4109 cgrp
= kzalloc(sizeof(*cgrp
), GFP_KERNEL
);
4113 name
= cgroup_alloc_name(dentry
);
4116 rcu_assign_pointer(cgrp
->name
, name
);
4118 cgrp
->id
= ida_simple_get(&root
->cgroup_ida
, 1, 0, GFP_KERNEL
);
4123 * Only live parents can have children. Note that the liveliness
4124 * check isn't strictly necessary because cgroup_mkdir() and
4125 * cgroup_rmdir() are fully synchronized by i_mutex; however, do it
4126 * anyway so that locking is contained inside cgroup proper and we
4127 * don't get nasty surprises if we ever grow another caller.
4129 if (!cgroup_lock_live_group(parent
)) {
4134 /* Grab a reference on the superblock so the hierarchy doesn't
4135 * get deleted on unmount if there are child cgroups. This
4136 * can be done outside cgroup_mutex, since the sb can't
4137 * disappear while someone has an open control file on the
4139 atomic_inc(&sb
->s_active
);
4141 init_cgroup_housekeeping(cgrp
);
4143 dentry
->d_fsdata
= cgrp
;
4144 cgrp
->dentry
= dentry
;
4146 cgrp
->parent
= parent
;
4147 cgrp
->root
= parent
->root
;
4148 cgrp
->top_cgroup
= parent
->top_cgroup
;
4150 if (notify_on_release(parent
))
4151 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
4153 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
))
4154 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
4156 for_each_subsys(root
, ss
) {
4157 struct cgroup_subsys_state
*css
;
4159 css
= ss
->css_alloc(cgrp
);
4164 init_cgroup_css(css
, ss
, cgrp
);
4166 err
= alloc_css_id(ss
, parent
, cgrp
);
4173 * Create directory. cgroup_create_file() returns with the new
4174 * directory locked on success so that it can be populated without
4175 * dropping cgroup_mutex.
4177 err
= cgroup_create_file(dentry
, S_IFDIR
| mode
, sb
);
4180 lockdep_assert_held(&dentry
->d_inode
->i_mutex
);
4182 /* allocation complete, commit to creation */
4183 list_add_tail(&cgrp
->allcg_node
, &root
->allcg_list
);
4184 list_add_tail_rcu(&cgrp
->sibling
, &cgrp
->parent
->children
);
4185 root
->number_of_cgroups
++;
4187 /* each css holds a ref to the cgroup's dentry */
4188 for_each_subsys(root
, ss
)
4191 /* hold a ref to the parent's dentry */
4192 dget(parent
->dentry
);
4194 /* creation succeeded, notify subsystems */
4195 for_each_subsys(root
, ss
) {
4196 err
= online_css(ss
, cgrp
);
4200 if (ss
->broken_hierarchy
&& !ss
->warned_broken_hierarchy
&&
4202 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",
4203 current
->comm
, current
->pid
, ss
->name
);
4204 if (!strcmp(ss
->name
, "memory"))
4205 pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
4206 ss
->warned_broken_hierarchy
= true;
4210 err
= cgroup_populate_dir(cgrp
, true, root
->subsys_mask
);
4214 mutex_unlock(&cgroup_mutex
);
4215 mutex_unlock(&cgrp
->dentry
->d_inode
->i_mutex
);
4220 for_each_subsys(root
, ss
) {
4221 if (cgrp
->subsys
[ss
->subsys_id
])
4224 mutex_unlock(&cgroup_mutex
);
4225 /* Release the reference count that we took on the superblock */
4226 deactivate_super(sb
);
4228 ida_simple_remove(&root
->cgroup_ida
, cgrp
->id
);
4230 kfree(rcu_dereference_raw(cgrp
->name
));
4236 cgroup_destroy_locked(cgrp
);
4237 mutex_unlock(&cgroup_mutex
);
4238 mutex_unlock(&dentry
->d_inode
->i_mutex
);
4242 static int cgroup_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
4244 struct cgroup
*c_parent
= dentry
->d_parent
->d_fsdata
;
4246 /* the vfs holds inode->i_mutex already */
4247 return cgroup_create(c_parent
, dentry
, mode
| S_IFDIR
);
4250 static int cgroup_destroy_locked(struct cgroup
*cgrp
)
4251 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
4253 struct dentry
*d
= cgrp
->dentry
;
4254 struct cgroup
*parent
= cgrp
->parent
;
4255 struct cgroup_event
*event
, *tmp
;
4256 struct cgroup_subsys
*ss
;
4258 lockdep_assert_held(&d
->d_inode
->i_mutex
);
4259 lockdep_assert_held(&cgroup_mutex
);
4261 if (atomic_read(&cgrp
->count
) || !list_empty(&cgrp
->children
))
4265 * Block new css_tryget() by deactivating refcnt and mark @cgrp
4266 * removed. This makes future css_tryget() and child creation
4267 * attempts fail thus maintaining the removal conditions verified
4270 for_each_subsys(cgrp
->root
, ss
) {
4271 struct cgroup_subsys_state
*css
= cgrp
->subsys
[ss
->subsys_id
];
4273 WARN_ON(atomic_read(&css
->refcnt
) < 0);
4274 atomic_add(CSS_DEACT_BIAS
, &css
->refcnt
);
4276 set_bit(CGRP_REMOVED
, &cgrp
->flags
);
4278 /* tell subsystems to initate destruction */
4279 for_each_subsys(cgrp
->root
, ss
)
4280 offline_css(ss
, cgrp
);
4283 * Put all the base refs. Each css holds an extra reference to the
4284 * cgroup's dentry and cgroup removal proceeds regardless of css
4285 * refs. On the last put of each css, whenever that may be, the
4286 * extra dentry ref is put so that dentry destruction happens only
4287 * after all css's are released.
4289 for_each_subsys(cgrp
->root
, ss
)
4290 css_put(cgrp
->subsys
[ss
->subsys_id
]);
4292 raw_spin_lock(&release_list_lock
);
4293 if (!list_empty(&cgrp
->release_list
))
4294 list_del_init(&cgrp
->release_list
);
4295 raw_spin_unlock(&release_list_lock
);
4297 /* delete this cgroup from parent->children */
4298 list_del_rcu(&cgrp
->sibling
);
4299 list_del_init(&cgrp
->allcg_node
);
4302 cgroup_d_remove_dir(d
);
4305 set_bit(CGRP_RELEASABLE
, &parent
->flags
);
4306 check_for_release(parent
);
4309 * Unregister events and notify userspace.
4310 * Notify userspace about cgroup removing only after rmdir of cgroup
4311 * directory to avoid race between userspace and kernelspace.
4313 spin_lock(&cgrp
->event_list_lock
);
4314 list_for_each_entry_safe(event
, tmp
, &cgrp
->event_list
, list
) {
4315 list_del_init(&event
->list
);
4316 schedule_work(&event
->remove
);
4318 spin_unlock(&cgrp
->event_list_lock
);
4323 static int cgroup_rmdir(struct inode
*unused_dir
, struct dentry
*dentry
)
4327 mutex_lock(&cgroup_mutex
);
4328 ret
= cgroup_destroy_locked(dentry
->d_fsdata
);
4329 mutex_unlock(&cgroup_mutex
);
4334 static void __init_or_module
cgroup_init_cftsets(struct cgroup_subsys
*ss
)
4336 INIT_LIST_HEAD(&ss
->cftsets
);
4339 * base_cftset is embedded in subsys itself, no need to worry about
4342 if (ss
->base_cftypes
) {
4343 ss
->base_cftset
.cfts
= ss
->base_cftypes
;
4344 list_add_tail(&ss
->base_cftset
.node
, &ss
->cftsets
);
4348 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
)
4350 struct cgroup_subsys_state
*css
;
4352 printk(KERN_INFO
"Initializing cgroup subsys %s\n", ss
->name
);
4354 mutex_lock(&cgroup_mutex
);
4356 /* init base cftset */
4357 cgroup_init_cftsets(ss
);
4359 /* Create the top cgroup state for this subsystem */
4360 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
4361 ss
->root
= &rootnode
;
4362 css
= ss
->css_alloc(dummytop
);
4363 /* We don't handle early failures gracefully */
4364 BUG_ON(IS_ERR(css
));
4365 init_cgroup_css(css
, ss
, dummytop
);
4367 /* Update the init_css_set to contain a subsys
4368 * pointer to this state - since the subsystem is
4369 * newly registered, all tasks and hence the
4370 * init_css_set is in the subsystem's top cgroup. */
4371 init_css_set
.subsys
[ss
->subsys_id
] = css
;
4373 need_forkexit_callback
|= ss
->fork
|| ss
->exit
;
4375 /* At system boot, before all subsystems have been
4376 * registered, no tasks have been forked, so we don't
4377 * need to invoke fork callbacks here. */
4378 BUG_ON(!list_empty(&init_task
.tasks
));
4381 BUG_ON(online_css(ss
, dummytop
));
4383 mutex_unlock(&cgroup_mutex
);
4385 /* this function shouldn't be used with modular subsystems, since they
4386 * need to register a subsys_id, among other things */
4391 * cgroup_load_subsys: load and register a modular subsystem at runtime
4392 * @ss: the subsystem to load
4394 * This function should be called in a modular subsystem's initcall. If the
4395 * subsystem is built as a module, it will be assigned a new subsys_id and set
4396 * up for use. If the subsystem is built-in anyway, work is delegated to the
4397 * simpler cgroup_init_subsys.
4399 int __init_or_module
cgroup_load_subsys(struct cgroup_subsys
*ss
)
4401 struct cgroup_subsys_state
*css
;
4403 struct hlist_node
*tmp
;
4407 /* check name and function validity */
4408 if (ss
->name
== NULL
|| strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
||
4409 ss
->css_alloc
== NULL
|| ss
->css_free
== NULL
)
4413 * we don't support callbacks in modular subsystems. this check is
4414 * before the ss->module check for consistency; a subsystem that could
4415 * be a module should still have no callbacks even if the user isn't
4416 * compiling it as one.
4418 if (ss
->fork
|| ss
->exit
)
4422 * an optionally modular subsystem is built-in: we want to do nothing,
4423 * since cgroup_init_subsys will have already taken care of it.
4425 if (ss
->module
== NULL
) {
4426 /* a sanity check */
4427 BUG_ON(subsys
[ss
->subsys_id
] != ss
);
4431 /* init base cftset */
4432 cgroup_init_cftsets(ss
);
4434 mutex_lock(&cgroup_mutex
);
4435 subsys
[ss
->subsys_id
] = ss
;
4438 * no ss->css_alloc seems to need anything important in the ss
4439 * struct, so this can happen first (i.e. before the rootnode
4442 css
= ss
->css_alloc(dummytop
);
4444 /* failure case - need to deassign the subsys[] slot. */
4445 subsys
[ss
->subsys_id
] = NULL
;
4446 mutex_unlock(&cgroup_mutex
);
4447 return PTR_ERR(css
);
4450 list_add(&ss
->sibling
, &rootnode
.subsys_list
);
4451 ss
->root
= &rootnode
;
4453 /* our new subsystem will be attached to the dummy hierarchy. */
4454 init_cgroup_css(css
, ss
, dummytop
);
4455 /* init_idr must be after init_cgroup_css because it sets css->id. */
4457 ret
= cgroup_init_idr(ss
, css
);
4463 * Now we need to entangle the css into the existing css_sets. unlike
4464 * in cgroup_init_subsys, there are now multiple css_sets, so each one
4465 * will need a new pointer to it; done by iterating the css_set_table.
4466 * furthermore, modifying the existing css_sets will corrupt the hash
4467 * table state, so each changed css_set will need its hash recomputed.
4468 * this is all done under the css_set_lock.
4470 write_lock(&css_set_lock
);
4471 hash_for_each_safe(css_set_table
, i
, tmp
, cg
, hlist
) {
4472 /* skip entries that we already rehashed */
4473 if (cg
->subsys
[ss
->subsys_id
])
4475 /* remove existing entry */
4476 hash_del(&cg
->hlist
);
4478 cg
->subsys
[ss
->subsys_id
] = css
;
4479 /* recompute hash and restore entry */
4480 key
= css_set_hash(cg
->subsys
);
4481 hash_add(css_set_table
, &cg
->hlist
, key
);
4483 write_unlock(&css_set_lock
);
4486 ret
= online_css(ss
, dummytop
);
4491 mutex_unlock(&cgroup_mutex
);
4495 mutex_unlock(&cgroup_mutex
);
4496 /* @ss can't be mounted here as try_module_get() would fail */
4497 cgroup_unload_subsys(ss
);
4500 EXPORT_SYMBOL_GPL(cgroup_load_subsys
);
4503 * cgroup_unload_subsys: unload a modular subsystem
4504 * @ss: the subsystem to unload
4506 * This function should be called in a modular subsystem's exitcall. When this
4507 * function is invoked, the refcount on the subsystem's module will be 0, so
4508 * the subsystem will not be attached to any hierarchy.
4510 void cgroup_unload_subsys(struct cgroup_subsys
*ss
)
4512 struct cg_cgroup_link
*link
;
4514 BUG_ON(ss
->module
== NULL
);
4517 * we shouldn't be called if the subsystem is in use, and the use of
4518 * try_module_get in parse_cgroupfs_options should ensure that it
4519 * doesn't start being used while we're killing it off.
4521 BUG_ON(ss
->root
!= &rootnode
);
4523 mutex_lock(&cgroup_mutex
);
4525 offline_css(ss
, dummytop
);
4529 idr_destroy(&ss
->idr
);
4531 /* deassign the subsys_id */
4532 subsys
[ss
->subsys_id
] = NULL
;
4534 /* remove subsystem from rootnode's list of subsystems */
4535 list_del_init(&ss
->sibling
);
4538 * disentangle the css from all css_sets attached to the dummytop. as
4539 * in loading, we need to pay our respects to the hashtable gods.
4541 write_lock(&css_set_lock
);
4542 list_for_each_entry(link
, &dummytop
->css_sets
, cgrp_link_list
) {
4543 struct css_set
*cg
= link
->cg
;
4546 hash_del(&cg
->hlist
);
4547 cg
->subsys
[ss
->subsys_id
] = NULL
;
4548 key
= css_set_hash(cg
->subsys
);
4549 hash_add(css_set_table
, &cg
->hlist
, key
);
4551 write_unlock(&css_set_lock
);
4554 * remove subsystem's css from the dummytop and free it - need to
4555 * free before marking as null because ss->css_free needs the
4556 * cgrp->subsys pointer to find their state. note that this also
4557 * takes care of freeing the css_id.
4559 ss
->css_free(dummytop
);
4560 dummytop
->subsys
[ss
->subsys_id
] = NULL
;
4562 mutex_unlock(&cgroup_mutex
);
4564 EXPORT_SYMBOL_GPL(cgroup_unload_subsys
);
4567 * cgroup_init_early - cgroup initialization at system boot
4569 * Initialize cgroups at system boot, and initialize any
4570 * subsystems that request early init.
4572 int __init
cgroup_init_early(void)
4575 atomic_set(&init_css_set
.refcount
, 1);
4576 INIT_LIST_HEAD(&init_css_set
.cg_links
);
4577 INIT_LIST_HEAD(&init_css_set
.tasks
);
4578 INIT_HLIST_NODE(&init_css_set
.hlist
);
4580 init_cgroup_root(&rootnode
);
4582 init_task
.cgroups
= &init_css_set
;
4584 init_css_set_link
.cg
= &init_css_set
;
4585 init_css_set_link
.cgrp
= dummytop
;
4586 list_add(&init_css_set_link
.cgrp_link_list
,
4587 &rootnode
.top_cgroup
.css_sets
);
4588 list_add(&init_css_set_link
.cg_link_list
,
4589 &init_css_set
.cg_links
);
4591 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4592 struct cgroup_subsys
*ss
= subsys
[i
];
4594 /* at bootup time, we don't worry about modular subsystems */
4595 if (!ss
|| ss
->module
)
4599 BUG_ON(strlen(ss
->name
) > MAX_CGROUP_TYPE_NAMELEN
);
4600 BUG_ON(!ss
->css_alloc
);
4601 BUG_ON(!ss
->css_free
);
4602 if (ss
->subsys_id
!= i
) {
4603 printk(KERN_ERR
"cgroup: Subsys %s id == %d\n",
4604 ss
->name
, ss
->subsys_id
);
4609 cgroup_init_subsys(ss
);
4615 * cgroup_init - cgroup initialization
4617 * Register cgroup filesystem and /proc file, and initialize
4618 * any subsystems that didn't request early init.
4620 int __init
cgroup_init(void)
4626 err
= bdi_init(&cgroup_backing_dev_info
);
4630 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4631 struct cgroup_subsys
*ss
= subsys
[i
];
4633 /* at bootup time, we don't worry about modular subsystems */
4634 if (!ss
|| ss
->module
)
4636 if (!ss
->early_init
)
4637 cgroup_init_subsys(ss
);
4639 cgroup_init_idr(ss
, init_css_set
.subsys
[ss
->subsys_id
]);
4642 /* Add init_css_set to the hash table */
4643 key
= css_set_hash(init_css_set
.subsys
);
4644 hash_add(css_set_table
, &init_css_set
.hlist
, key
);
4645 BUG_ON(!init_root_id(&rootnode
));
4647 cgroup_kobj
= kobject_create_and_add("cgroup", fs_kobj
);
4653 err
= register_filesystem(&cgroup_fs_type
);
4655 kobject_put(cgroup_kobj
);
4659 proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
);
4663 bdi_destroy(&cgroup_backing_dev_info
);
4669 * proc_cgroup_show()
4670 * - Print task's cgroup paths into seq_file, one line for each hierarchy
4671 * - Used for /proc/<pid>/cgroup.
4672 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
4673 * doesn't really matter if tsk->cgroup changes after we read it,
4674 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
4675 * anyway. No need to check that tsk->cgroup != NULL, thanks to
4676 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
4677 * cgroup to top_cgroup.
4680 /* TODO: Use a proper seq_file iterator */
4681 static int proc_cgroup_show(struct seq_file
*m
, void *v
)
4684 struct task_struct
*tsk
;
4687 struct cgroupfs_root
*root
;
4690 buf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
4696 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
4702 mutex_lock(&cgroup_mutex
);
4704 for_each_active_root(root
) {
4705 struct cgroup_subsys
*ss
;
4706 struct cgroup
*cgrp
;
4709 seq_printf(m
, "%d:", root
->hierarchy_id
);
4710 for_each_subsys(root
, ss
)
4711 seq_printf(m
, "%s%s", count
++ ? "," : "", ss
->name
);
4712 if (strlen(root
->name
))
4713 seq_printf(m
, "%sname=%s", count
? "," : "",
4716 cgrp
= task_cgroup_from_root(tsk
, root
);
4717 retval
= cgroup_path(cgrp
, buf
, PAGE_SIZE
);
4725 mutex_unlock(&cgroup_mutex
);
4726 put_task_struct(tsk
);
4733 static int cgroup_open(struct inode
*inode
, struct file
*file
)
4735 struct pid
*pid
= PROC_I(inode
)->pid
;
4736 return single_open(file
, proc_cgroup_show
, pid
);
4739 const struct file_operations proc_cgroup_operations
= {
4740 .open
= cgroup_open
,
4742 .llseek
= seq_lseek
,
4743 .release
= single_release
,
4746 /* Display information about each subsystem and each hierarchy */
4747 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
4751 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
4753 * ideally we don't want subsystems moving around while we do this.
4754 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
4755 * subsys/hierarchy state.
4757 mutex_lock(&cgroup_mutex
);
4758 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
4759 struct cgroup_subsys
*ss
= subsys
[i
];
4762 seq_printf(m
, "%s\t%d\t%d\t%d\n",
4763 ss
->name
, ss
->root
->hierarchy_id
,
4764 ss
->root
->number_of_cgroups
, !ss
->disabled
);
4766 mutex_unlock(&cgroup_mutex
);
4770 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
4772 return single_open(file
, proc_cgroupstats_show
, NULL
);
4775 static const struct file_operations proc_cgroupstats_operations
= {
4776 .open
= cgroupstats_open
,
4778 .llseek
= seq_lseek
,
4779 .release
= single_release
,
4783 * cgroup_fork - attach newly forked task to its parents cgroup.
4784 * @child: pointer to task_struct of forking parent process.
4786 * Description: A task inherits its parent's cgroup at fork().
4788 * A pointer to the shared css_set was automatically copied in
4789 * fork.c by dup_task_struct(). However, we ignore that copy, since
4790 * it was not made under the protection of RCU or cgroup_mutex, so
4791 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
4792 * have already changed current->cgroups, allowing the previously
4793 * referenced cgroup group to be removed and freed.
4795 * At the point that cgroup_fork() is called, 'current' is the parent
4796 * task, and the passed argument 'child' points to the child task.
4798 void cgroup_fork(struct task_struct
*child
)
4801 child
->cgroups
= current
->cgroups
;
4802 get_css_set(child
->cgroups
);
4803 task_unlock(current
);
4804 INIT_LIST_HEAD(&child
->cg_list
);
4808 * cgroup_post_fork - called on a new task after adding it to the task list
4809 * @child: the task in question
4811 * Adds the task to the list running through its css_set if necessary and
4812 * call the subsystem fork() callbacks. Has to be after the task is
4813 * visible on the task list in case we race with the first call to
4814 * cgroup_iter_start() - to guarantee that the new task ends up on its
4817 void cgroup_post_fork(struct task_struct
*child
)
4822 * use_task_css_set_links is set to 1 before we walk the tasklist
4823 * under the tasklist_lock and we read it here after we added the child
4824 * to the tasklist under the tasklist_lock as well. If the child wasn't
4825 * yet in the tasklist when we walked through it from
4826 * cgroup_enable_task_cg_lists(), then use_task_css_set_links value
4827 * should be visible now due to the paired locking and barriers implied
4828 * by LOCK/UNLOCK: it is written before the tasklist_lock unlock
4829 * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
4832 if (use_task_css_set_links
) {
4833 write_lock(&css_set_lock
);
4835 if (list_empty(&child
->cg_list
))
4836 list_add(&child
->cg_list
, &child
->cgroups
->tasks
);
4838 write_unlock(&css_set_lock
);
4842 * Call ss->fork(). This must happen after @child is linked on
4843 * css_set; otherwise, @child might change state between ->fork()
4844 * and addition to css_set.
4846 if (need_forkexit_callback
) {
4848 * fork/exit callbacks are supported only for builtin
4849 * subsystems, and the builtin section of the subsys
4850 * array is immutable, so we don't need to lock the
4851 * subsys array here. On the other hand, modular section
4852 * of the array can be freed at module unload, so we
4855 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
4856 struct cgroup_subsys
*ss
= subsys
[i
];
4865 * cgroup_exit - detach cgroup from exiting task
4866 * @tsk: pointer to task_struct of exiting process
4867 * @run_callback: run exit callbacks?
4869 * Description: Detach cgroup from @tsk and release it.
4871 * Note that cgroups marked notify_on_release force every task in
4872 * them to take the global cgroup_mutex mutex when exiting.
4873 * This could impact scaling on very large systems. Be reluctant to
4874 * use notify_on_release cgroups where very high task exit scaling
4875 * is required on large systems.
4877 * the_top_cgroup_hack:
4879 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
4881 * We call cgroup_exit() while the task is still competent to
4882 * handle notify_on_release(), then leave the task attached to the
4883 * root cgroup in each hierarchy for the remainder of its exit.
4885 * To do this properly, we would increment the reference count on
4886 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
4887 * code we would add a second cgroup function call, to drop that
4888 * reference. This would just create an unnecessary hot spot on
4889 * the top_cgroup reference count, to no avail.
4891 * Normally, holding a reference to a cgroup without bumping its
4892 * count is unsafe. The cgroup could go away, or someone could
4893 * attach us to a different cgroup, decrementing the count on
4894 * the first cgroup that we never incremented. But in this case,
4895 * top_cgroup isn't going away, and either task has PF_EXITING set,
4896 * which wards off any cgroup_attach_task() attempts, or task is a failed
4897 * fork, never visible to cgroup_attach_task.
4899 void cgroup_exit(struct task_struct
*tsk
, int run_callbacks
)
4905 * Unlink from the css_set task list if necessary.
4906 * Optimistically check cg_list before taking
4909 if (!list_empty(&tsk
->cg_list
)) {
4910 write_lock(&css_set_lock
);
4911 if (!list_empty(&tsk
->cg_list
))
4912 list_del_init(&tsk
->cg_list
);
4913 write_unlock(&css_set_lock
);
4916 /* Reassign the task to the init_css_set. */
4919 tsk
->cgroups
= &init_css_set
;
4921 if (run_callbacks
&& need_forkexit_callback
) {
4923 * fork/exit callbacks are supported only for builtin
4924 * subsystems, see cgroup_post_fork() for details.
4926 for (i
= 0; i
< CGROUP_BUILTIN_SUBSYS_COUNT
; i
++) {
4927 struct cgroup_subsys
*ss
= subsys
[i
];
4930 struct cgroup
*old_cgrp
=
4931 rcu_dereference_raw(cg
->subsys
[i
])->cgroup
;
4932 struct cgroup
*cgrp
= task_cgroup(tsk
, i
);
4933 ss
->exit(cgrp
, old_cgrp
, tsk
);
4939 put_css_set_taskexit(cg
);
4942 static void check_for_release(struct cgroup
*cgrp
)
4944 /* All of these checks rely on RCU to keep the cgroup
4945 * structure alive */
4946 if (cgroup_is_releasable(cgrp
) &&
4947 !atomic_read(&cgrp
->count
) && list_empty(&cgrp
->children
)) {
4949 * Control Group is currently removeable. If it's not
4950 * already queued for a userspace notification, queue
4953 int need_schedule_work
= 0;
4955 raw_spin_lock(&release_list_lock
);
4956 if (!cgroup_is_removed(cgrp
) &&
4957 list_empty(&cgrp
->release_list
)) {
4958 list_add(&cgrp
->release_list
, &release_list
);
4959 need_schedule_work
= 1;
4961 raw_spin_unlock(&release_list_lock
);
4962 if (need_schedule_work
)
4963 schedule_work(&release_agent_work
);
4967 /* Caller must verify that the css is not for root cgroup */
4968 bool __css_tryget(struct cgroup_subsys_state
*css
)
4973 v
= css_refcnt(css
);
4974 t
= atomic_cmpxchg(&css
->refcnt
, v
, v
+ 1);
4982 EXPORT_SYMBOL_GPL(__css_tryget
);
4984 /* Caller must verify that the css is not for root cgroup */
4985 void __css_put(struct cgroup_subsys_state
*css
)
4989 v
= css_unbias_refcnt(atomic_dec_return(&css
->refcnt
));
4991 schedule_work(&css
->dput_work
);
4993 EXPORT_SYMBOL_GPL(__css_put
);
4996 * Notify userspace when a cgroup is released, by running the
4997 * configured release agent with the name of the cgroup (path
4998 * relative to the root of cgroup file system) as the argument.
5000 * Most likely, this user command will try to rmdir this cgroup.
5002 * This races with the possibility that some other task will be
5003 * attached to this cgroup before it is removed, or that some other
5004 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
5005 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
5006 * unused, and this cgroup will be reprieved from its death sentence,
5007 * to continue to serve a useful existence. Next time it's released,
5008 * we will get notified again, if it still has 'notify_on_release' set.
5010 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
5011 * means only wait until the task is successfully execve()'d. The
5012 * separate release agent task is forked by call_usermodehelper(),
5013 * then control in this thread returns here, without waiting for the
5014 * release agent task. We don't bother to wait because the caller of
5015 * this routine has no use for the exit status of the release agent
5016 * task, so no sense holding our caller up for that.
5018 static void cgroup_release_agent(struct work_struct
*work
)
5020 BUG_ON(work
!= &release_agent_work
);
5021 mutex_lock(&cgroup_mutex
);
5022 raw_spin_lock(&release_list_lock
);
5023 while (!list_empty(&release_list
)) {
5024 char *argv
[3], *envp
[3];
5026 char *pathbuf
= NULL
, *agentbuf
= NULL
;
5027 struct cgroup
*cgrp
= list_entry(release_list
.next
,
5030 list_del_init(&cgrp
->release_list
);
5031 raw_spin_unlock(&release_list_lock
);
5032 pathbuf
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
5035 if (cgroup_path(cgrp
, pathbuf
, PAGE_SIZE
) < 0)
5037 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
5042 argv
[i
++] = agentbuf
;
5043 argv
[i
++] = pathbuf
;
5047 /* minimal command environment */
5048 envp
[i
++] = "HOME=/";
5049 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
5052 /* Drop the lock while we invoke the usermode helper,
5053 * since the exec could involve hitting disk and hence
5054 * be a slow process */
5055 mutex_unlock(&cgroup_mutex
);
5056 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
5057 mutex_lock(&cgroup_mutex
);
5061 raw_spin_lock(&release_list_lock
);
5063 raw_spin_unlock(&release_list_lock
);
5064 mutex_unlock(&cgroup_mutex
);
5067 static int __init
cgroup_disable(char *str
)
5072 while ((token
= strsep(&str
, ",")) != NULL
) {
5075 for (i
= 0; i
< CGROUP_SUBSYS_COUNT
; i
++) {
5076 struct cgroup_subsys
*ss
= subsys
[i
];
5079 * cgroup_disable, being at boot time, can't
5080 * know about module subsystems, so we don't
5083 if (!ss
|| ss
->module
)
5086 if (!strcmp(token
, ss
->name
)) {
5088 printk(KERN_INFO
"Disabling %s control group"
5089 " subsystem\n", ss
->name
);
5096 __setup("cgroup_disable=", cgroup_disable
);
5099 * Functons for CSS ID.
5103 *To get ID other than 0, this should be called when !cgroup_is_removed().
5105 unsigned short css_id(struct cgroup_subsys_state
*css
)
5107 struct css_id
*cssid
;
5110 * This css_id() can return correct value when somone has refcnt
5111 * on this or this is under rcu_read_lock(). Once css->id is allocated,
5112 * it's unchanged until freed.
5114 cssid
= rcu_dereference_check(css
->id
, css_refcnt(css
));
5120 EXPORT_SYMBOL_GPL(css_id
);
5122 unsigned short css_depth(struct cgroup_subsys_state
*css
)
5124 struct css_id
*cssid
;
5126 cssid
= rcu_dereference_check(css
->id
, css_refcnt(css
));
5129 return cssid
->depth
;
5132 EXPORT_SYMBOL_GPL(css_depth
);
5135 * css_is_ancestor - test "root" css is an ancestor of "child"
5136 * @child: the css to be tested.
5137 * @root: the css supporsed to be an ancestor of the child.
5139 * Returns true if "root" is an ancestor of "child" in its hierarchy. Because
5140 * this function reads css->id, the caller must hold rcu_read_lock().
5141 * But, considering usual usage, the csses should be valid objects after test.
5142 * Assuming that the caller will do some action to the child if this returns
5143 * returns true, the caller must take "child";s reference count.
5144 * If "child" is valid object and this returns true, "root" is valid, too.
5147 bool css_is_ancestor(struct cgroup_subsys_state
*child
,
5148 const struct cgroup_subsys_state
*root
)
5150 struct css_id
*child_id
;
5151 struct css_id
*root_id
;
5153 child_id
= rcu_dereference(child
->id
);
5156 root_id
= rcu_dereference(root
->id
);
5159 if (child_id
->depth
< root_id
->depth
)
5161 if (child_id
->stack
[root_id
->depth
] != root_id
->id
)
5166 void free_css_id(struct cgroup_subsys
*ss
, struct cgroup_subsys_state
*css
)
5168 struct css_id
*id
= css
->id
;
5169 /* When this is called before css_id initialization, id can be NULL */
5173 BUG_ON(!ss
->use_id
);
5175 rcu_assign_pointer(id
->css
, NULL
);
5176 rcu_assign_pointer(css
->id
, NULL
);
5177 spin_lock(&ss
->id_lock
);
5178 idr_remove(&ss
->idr
, id
->id
);
5179 spin_unlock(&ss
->id_lock
);
5180 kfree_rcu(id
, rcu_head
);
5182 EXPORT_SYMBOL_GPL(free_css_id
);
5185 * This is called by init or create(). Then, calls to this function are
5186 * always serialized (By cgroup_mutex() at create()).
5189 static struct css_id
*get_new_cssid(struct cgroup_subsys
*ss
, int depth
)
5191 struct css_id
*newid
;
5194 BUG_ON(!ss
->use_id
);
5196 size
= sizeof(*newid
) + sizeof(unsigned short) * (depth
+ 1);
5197 newid
= kzalloc(size
, GFP_KERNEL
);
5199 return ERR_PTR(-ENOMEM
);
5201 idr_preload(GFP_KERNEL
);
5202 spin_lock(&ss
->id_lock
);
5203 /* Don't use 0. allocates an ID of 1-65535 */
5204 ret
= idr_alloc(&ss
->idr
, newid
, 1, CSS_ID_MAX
+ 1, GFP_NOWAIT
);
5205 spin_unlock(&ss
->id_lock
);
5208 /* Returns error when there are no free spaces for new ID.*/
5213 newid
->depth
= depth
;
5217 return ERR_PTR(ret
);
5221 static int __init_or_module
cgroup_init_idr(struct cgroup_subsys
*ss
,
5222 struct cgroup_subsys_state
*rootcss
)
5224 struct css_id
*newid
;
5226 spin_lock_init(&ss
->id_lock
);
5229 newid
= get_new_cssid(ss
, 0);
5231 return PTR_ERR(newid
);
5233 newid
->stack
[0] = newid
->id
;
5234 newid
->css
= rootcss
;
5235 rootcss
->id
= newid
;
5239 static int alloc_css_id(struct cgroup_subsys
*ss
, struct cgroup
*parent
,
5240 struct cgroup
*child
)
5242 int subsys_id
, i
, depth
= 0;
5243 struct cgroup_subsys_state
*parent_css
, *child_css
;
5244 struct css_id
*child_id
, *parent_id
;
5246 subsys_id
= ss
->subsys_id
;
5247 parent_css
= parent
->subsys
[subsys_id
];
5248 child_css
= child
->subsys
[subsys_id
];
5249 parent_id
= parent_css
->id
;
5250 depth
= parent_id
->depth
+ 1;
5252 child_id
= get_new_cssid(ss
, depth
);
5253 if (IS_ERR(child_id
))
5254 return PTR_ERR(child_id
);
5256 for (i
= 0; i
< depth
; i
++)
5257 child_id
->stack
[i
] = parent_id
->stack
[i
];
5258 child_id
->stack
[depth
] = child_id
->id
;
5260 * child_id->css pointer will be set after this cgroup is available
5261 * see cgroup_populate_dir()
5263 rcu_assign_pointer(child_css
->id
, child_id
);
5269 * css_lookup - lookup css by id
5270 * @ss: cgroup subsys to be looked into.
5273 * Returns pointer to cgroup_subsys_state if there is valid one with id.
5274 * NULL if not. Should be called under rcu_read_lock()
5276 struct cgroup_subsys_state
*css_lookup(struct cgroup_subsys
*ss
, int id
)
5278 struct css_id
*cssid
= NULL
;
5280 BUG_ON(!ss
->use_id
);
5281 cssid
= idr_find(&ss
->idr
, id
);
5283 if (unlikely(!cssid
))
5286 return rcu_dereference(cssid
->css
);
5288 EXPORT_SYMBOL_GPL(css_lookup
);
5291 * css_get_next - lookup next cgroup under specified hierarchy.
5292 * @ss: pointer to subsystem
5293 * @id: current position of iteration.
5294 * @root: pointer to css. search tree under this.
5295 * @foundid: position of found object.
5297 * Search next css under the specified hierarchy of rootid. Calling under
5298 * rcu_read_lock() is necessary. Returns NULL if it reaches the end.
5300 struct cgroup_subsys_state
*
5301 css_get_next(struct cgroup_subsys
*ss
, int id
,
5302 struct cgroup_subsys_state
*root
, int *foundid
)
5304 struct cgroup_subsys_state
*ret
= NULL
;
5307 int rootid
= css_id(root
);
5308 int depth
= css_depth(root
);
5313 BUG_ON(!ss
->use_id
);
5314 WARN_ON_ONCE(!rcu_read_lock_held());
5316 /* fill start point for scan */
5320 * scan next entry from bitmap(tree), tmpid is updated after
5323 tmp
= idr_get_next(&ss
->idr
, &tmpid
);
5326 if (tmp
->depth
>= depth
&& tmp
->stack
[depth
] == rootid
) {
5327 ret
= rcu_dereference(tmp
->css
);
5333 /* continue to scan from next id */
5340 * get corresponding css from file open on cgroupfs directory
5342 struct cgroup_subsys_state
*cgroup_css_from_dir(struct file
*f
, int id
)
5344 struct cgroup
*cgrp
;
5345 struct inode
*inode
;
5346 struct cgroup_subsys_state
*css
;
5348 inode
= file_inode(f
);
5349 /* check in cgroup filesystem dir */
5350 if (inode
->i_op
!= &cgroup_dir_inode_operations
)
5351 return ERR_PTR(-EBADF
);
5353 if (id
< 0 || id
>= CGROUP_SUBSYS_COUNT
)
5354 return ERR_PTR(-EINVAL
);
5357 cgrp
= __d_cgrp(f
->f_dentry
);
5358 css
= cgrp
->subsys
[id
];
5359 return css
? css
: ERR_PTR(-ENOENT
);
5362 #ifdef CONFIG_CGROUP_DEBUG
5363 static struct cgroup_subsys_state
*debug_css_alloc(struct cgroup
*cont
)
5365 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
5368 return ERR_PTR(-ENOMEM
);
5373 static void debug_css_free(struct cgroup
*cont
)
5375 kfree(cont
->subsys
[debug_subsys_id
]);
5378 static u64
cgroup_refcount_read(struct cgroup
*cont
, struct cftype
*cft
)
5380 return atomic_read(&cont
->count
);
5383 static u64
debug_taskcount_read(struct cgroup
*cont
, struct cftype
*cft
)
5385 return cgroup_task_count(cont
);
5388 static u64
current_css_set_read(struct cgroup
*cont
, struct cftype
*cft
)
5390 return (u64
)(unsigned long)current
->cgroups
;
5393 static u64
current_css_set_refcount_read(struct cgroup
*cont
,
5399 count
= atomic_read(¤t
->cgroups
->refcount
);
5404 static int current_css_set_cg_links_read(struct cgroup
*cont
,
5406 struct seq_file
*seq
)
5408 struct cg_cgroup_link
*link
;
5411 read_lock(&css_set_lock
);
5413 cg
= rcu_dereference(current
->cgroups
);
5414 list_for_each_entry(link
, &cg
->cg_links
, cg_link_list
) {
5415 struct cgroup
*c
= link
->cgrp
;
5419 name
= c
->dentry
->d_name
.name
;
5422 seq_printf(seq
, "Root %d group %s\n",
5423 c
->root
->hierarchy_id
, name
);
5426 read_unlock(&css_set_lock
);
5430 #define MAX_TASKS_SHOWN_PER_CSS 25
5431 static int cgroup_css_links_read(struct cgroup
*cont
,
5433 struct seq_file
*seq
)
5435 struct cg_cgroup_link
*link
;
5437 read_lock(&css_set_lock
);
5438 list_for_each_entry(link
, &cont
->css_sets
, cgrp_link_list
) {
5439 struct css_set
*cg
= link
->cg
;
5440 struct task_struct
*task
;
5442 seq_printf(seq
, "css_set %p\n", cg
);
5443 list_for_each_entry(task
, &cg
->tasks
, cg_list
) {
5444 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
) {
5445 seq_puts(seq
, " ...\n");
5448 seq_printf(seq
, " task %d\n",
5449 task_pid_vnr(task
));
5453 read_unlock(&css_set_lock
);
5457 static u64
releasable_read(struct cgroup
*cgrp
, struct cftype
*cft
)
5459 return test_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
5462 static struct cftype debug_files
[] = {
5464 .name
= "cgroup_refcount",
5465 .read_u64
= cgroup_refcount_read
,
5468 .name
= "taskcount",
5469 .read_u64
= debug_taskcount_read
,
5473 .name
= "current_css_set",
5474 .read_u64
= current_css_set_read
,
5478 .name
= "current_css_set_refcount",
5479 .read_u64
= current_css_set_refcount_read
,
5483 .name
= "current_css_set_cg_links",
5484 .read_seq_string
= current_css_set_cg_links_read
,
5488 .name
= "cgroup_css_links",
5489 .read_seq_string
= cgroup_css_links_read
,
5493 .name
= "releasable",
5494 .read_u64
= releasable_read
,
5500 struct cgroup_subsys debug_subsys
= {
5502 .css_alloc
= debug_css_alloc
,
5503 .css_free
= debug_css_free
,
5504 .subsys_id
= debug_subsys_id
,
5505 .base_cftypes
= debug_files
,
5507 #endif /* CONFIG_CGROUP_DEBUG */