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/slab.h>
44 #include <linux/spinlock.h>
45 #include <linux/string.h>
46 #include <linux/sort.h>
47 #include <linux/kmod.h>
48 #include <linux/delayacct.h>
49 #include <linux/cgroupstats.h>
50 #include <linux/hashtable.h>
51 #include <linux/pid_namespace.h>
52 #include <linux/idr.h>
53 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
54 #include <linux/flex_array.h> /* used in cgroup_attach_task */
55 #include <linux/kthread.h>
57 #include <linux/atomic.h>
60 * pidlists linger the following amount before being destroyed. The goal
61 * is avoiding frequent destruction in the middle of consecutive read calls
62 * Expiring in the middle is a performance problem not a correctness one.
63 * 1 sec should be enough.
65 #define CGROUP_PIDLIST_DESTROY_DELAY HZ
67 #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
71 * cgroup_tree_mutex nests above cgroup_mutex and protects cftypes, file
72 * creation/removal and hierarchy changing operations including cgroup
73 * creation, removal, css association and controller rebinding. This outer
74 * lock is needed mainly to resolve the circular dependency between kernfs
75 * active ref and cgroup_mutex. cgroup_tree_mutex nests above both.
77 static DEFINE_MUTEX(cgroup_tree_mutex
);
80 * cgroup_mutex is the master lock. Any modification to cgroup or its
81 * hierarchy must be performed while holding it.
83 #ifdef CONFIG_PROVE_RCU
84 DEFINE_MUTEX(cgroup_mutex
);
85 EXPORT_SYMBOL_GPL(cgroup_mutex
); /* only for lockdep */
87 static DEFINE_MUTEX(cgroup_mutex
);
91 * Protects cgroup_subsys->release_agent_path. Modifying it also requires
92 * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
94 static DEFINE_SPINLOCK(release_agent_path_lock
);
96 #define cgroup_assert_mutexes_or_rcu_locked() \
97 rcu_lockdep_assert(rcu_read_lock_held() || \
98 lockdep_is_held(&cgroup_tree_mutex) || \
99 lockdep_is_held(&cgroup_mutex), \
100 "cgroup_[tree_]mutex or RCU read lock required");
103 * cgroup destruction makes heavy use of work items and there can be a lot
104 * of concurrent destructions. Use a separate workqueue so that cgroup
105 * destruction work items don't end up filling up max_active of system_wq
106 * which may lead to deadlock.
108 static struct workqueue_struct
*cgroup_destroy_wq
;
111 * pidlist destructions need to be flushed on cgroup destruction. Use a
112 * separate workqueue as flush domain.
114 static struct workqueue_struct
*cgroup_pidlist_destroy_wq
;
116 /* generate an array of cgroup subsystem pointers */
117 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
118 static struct cgroup_subsys
*cgroup_subsys
[] = {
119 #include <linux/cgroup_subsys.h>
123 /* array of cgroup subsystem names */
124 #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
125 static const char *cgroup_subsys_name
[] = {
126 #include <linux/cgroup_subsys.h>
131 * The dummy hierarchy, reserved for the subsystems that are otherwise
132 * unattached - it never has more than a single cgroup, and all tasks are
133 * part of that cgroup.
135 static struct cgroupfs_root cgroup_dummy_root
;
137 /* dummy_top is a shorthand for the dummy hierarchy's top cgroup */
138 static struct cgroup
* const cgroup_dummy_top
= &cgroup_dummy_root
.top_cgroup
;
140 /* The list of hierarchy roots */
142 static LIST_HEAD(cgroup_roots
);
143 static int cgroup_root_count
;
145 /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
146 static DEFINE_IDR(cgroup_hierarchy_idr
);
149 * Assign a monotonically increasing serial number to cgroups. It
150 * guarantees cgroups with bigger numbers are newer than those with smaller
151 * numbers. Also, as cgroups are always appended to the parent's
152 * ->children list, it guarantees that sibling cgroups are always sorted in
153 * the ascending serial number order on the list. Protected by
156 static u64 cgroup_serial_nr_next
= 1;
158 /* This flag indicates whether tasks in the fork and exit paths should
159 * check for fork/exit handlers to call. This avoids us having to do
160 * extra work in the fork/exit path if none of the subsystems need to
163 static int need_forkexit_callback __read_mostly
;
165 static struct cftype cgroup_base_files
[];
167 static void cgroup_put(struct cgroup
*cgrp
);
168 static int rebind_subsystems(struct cgroupfs_root
*root
,
169 unsigned long added_mask
, unsigned removed_mask
);
170 static void cgroup_destroy_css_killed(struct cgroup
*cgrp
);
171 static int cgroup_destroy_locked(struct cgroup
*cgrp
);
172 static int cgroup_addrm_files(struct cgroup
*cgrp
, struct cftype cfts
[],
174 static void cgroup_pidlist_destroy_all(struct cgroup
*cgrp
);
177 * cgroup_css - obtain a cgroup's css for the specified subsystem
178 * @cgrp: the cgroup of interest
179 * @ss: the subsystem of interest (%NULL returns the dummy_css)
181 * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
182 * function must be called either under cgroup_mutex or rcu_read_lock() and
183 * the caller is responsible for pinning the returned css if it wants to
184 * keep accessing it outside the said locks. This function may return
185 * %NULL if @cgrp doesn't have @subsys_id enabled.
187 static struct cgroup_subsys_state
*cgroup_css(struct cgroup
*cgrp
,
188 struct cgroup_subsys
*ss
)
191 return rcu_dereference_check(cgrp
->subsys
[ss
->id
],
192 lockdep_is_held(&cgroup_tree_mutex
) ||
193 lockdep_is_held(&cgroup_mutex
));
195 return &cgrp
->dummy_css
;
198 /* convenient tests for these bits */
199 static inline bool cgroup_is_dead(const struct cgroup
*cgrp
)
201 return test_bit(CGRP_DEAD
, &cgrp
->flags
);
204 struct cgroup_subsys_state
*seq_css(struct seq_file
*seq
)
206 struct kernfs_open_file
*of
= seq
->private;
207 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
208 struct cftype
*cft
= seq_cft(seq
);
211 * This is open and unprotected implementation of cgroup_css().
212 * seq_css() is only called from a kernfs file operation which has
213 * an active reference on the file. Because all the subsystem
214 * files are drained before a css is disassociated with a cgroup,
215 * the matching css from the cgroup's subsys table is guaranteed to
216 * be and stay valid until the enclosing operation is complete.
219 return rcu_dereference_raw(cgrp
->subsys
[cft
->ss
->id
]);
221 return &cgrp
->dummy_css
;
223 EXPORT_SYMBOL_GPL(seq_css
);
226 * cgroup_is_descendant - test ancestry
227 * @cgrp: the cgroup to be tested
228 * @ancestor: possible ancestor of @cgrp
230 * Test whether @cgrp is a descendant of @ancestor. It also returns %true
231 * if @cgrp == @ancestor. This function is safe to call as long as @cgrp
232 * and @ancestor are accessible.
234 bool cgroup_is_descendant(struct cgroup
*cgrp
, struct cgroup
*ancestor
)
237 if (cgrp
== ancestor
)
243 EXPORT_SYMBOL_GPL(cgroup_is_descendant
);
245 static int cgroup_is_releasable(const struct cgroup
*cgrp
)
248 (1 << CGRP_RELEASABLE
) |
249 (1 << CGRP_NOTIFY_ON_RELEASE
);
250 return (cgrp
->flags
& bits
) == bits
;
253 static int notify_on_release(const struct cgroup
*cgrp
)
255 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
259 * for_each_css - iterate all css's of a cgroup
260 * @css: the iteration cursor
261 * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
262 * @cgrp: the target cgroup to iterate css's of
264 * Should be called under cgroup_mutex.
266 #define for_each_css(css, ssid, cgrp) \
267 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
268 if (!((css) = rcu_dereference_check( \
269 (cgrp)->subsys[(ssid)], \
270 lockdep_is_held(&cgroup_tree_mutex) || \
271 lockdep_is_held(&cgroup_mutex)))) { } \
275 * for_each_subsys - iterate all enabled cgroup subsystems
276 * @ss: the iteration cursor
277 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
279 #define for_each_subsys(ss, ssid) \
280 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
281 (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
283 /* iterate across the active hierarchies */
284 #define for_each_active_root(root) \
285 list_for_each_entry((root), &cgroup_roots, root_list)
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_dead(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
);
313 * A cgroup can be associated with multiple css_sets as different tasks may
314 * belong to different cgroups on different hierarchies. In the other
315 * direction, a css_set is naturally associated with multiple cgroups.
316 * This M:N relationship is represented by the following link structure
317 * which exists for each association and allows traversing the associations
320 struct cgrp_cset_link
{
321 /* the cgroup and css_set this link associates */
323 struct css_set
*cset
;
325 /* list of cgrp_cset_links anchored at cgrp->cset_links */
326 struct list_head cset_link
;
328 /* list of cgrp_cset_links anchored at css_set->cgrp_links */
329 struct list_head cgrp_link
;
332 /* The default css_set - used by init and its children prior to any
333 * hierarchies being mounted. It contains a pointer to the root state
334 * for each subsystem. Also used to anchor the list of css_sets. Not
335 * reference-counted, to improve performance when child cgroups
336 * haven't been created.
339 static struct css_set init_css_set
;
340 static struct cgrp_cset_link init_cgrp_cset_link
;
343 * css_set_lock protects the list of css_set objects, and the chain of
344 * tasks off each css_set. Nests outside task->alloc_lock due to
345 * css_task_iter_start().
347 static DEFINE_RWLOCK(css_set_lock
);
348 static int css_set_count
;
351 * hash table for cgroup groups. This improves the performance to find
352 * an existing css_set. This hash doesn't (currently) take into
353 * account cgroups in empty hierarchies.
355 #define CSS_SET_HASH_BITS 7
356 static DEFINE_HASHTABLE(css_set_table
, CSS_SET_HASH_BITS
);
358 static unsigned long css_set_hash(struct cgroup_subsys_state
*css
[])
360 unsigned long key
= 0UL;
361 struct cgroup_subsys
*ss
;
364 for_each_subsys(ss
, i
)
365 key
+= (unsigned long)css
[i
];
366 key
= (key
>> 16) ^ key
;
372 * We don't maintain the lists running through each css_set to its task
373 * until after the first call to css_task_iter_start(). This reduces the
374 * fork()/exit() overhead for people who have cgroups compiled into their
375 * kernel but not actually in use.
377 static int use_task_css_set_links __read_mostly
;
379 static void __put_css_set(struct css_set
*cset
, int taskexit
)
381 struct cgrp_cset_link
*link
, *tmp_link
;
384 * Ensure that the refcount doesn't hit zero while any readers
385 * can see it. Similar to atomic_dec_and_lock(), but for an
388 if (atomic_add_unless(&cset
->refcount
, -1, 1))
390 write_lock(&css_set_lock
);
391 if (!atomic_dec_and_test(&cset
->refcount
)) {
392 write_unlock(&css_set_lock
);
396 /* This css_set is dead. unlink it and release cgroup refcounts */
397 hash_del(&cset
->hlist
);
400 list_for_each_entry_safe(link
, tmp_link
, &cset
->cgrp_links
, cgrp_link
) {
401 struct cgroup
*cgrp
= link
->cgrp
;
403 list_del(&link
->cset_link
);
404 list_del(&link
->cgrp_link
);
406 /* @cgrp can't go away while we're holding css_set_lock */
407 if (list_empty(&cgrp
->cset_links
) && notify_on_release(cgrp
)) {
409 set_bit(CGRP_RELEASABLE
, &cgrp
->flags
);
410 check_for_release(cgrp
);
416 write_unlock(&css_set_lock
);
417 kfree_rcu(cset
, rcu_head
);
421 * refcounted get/put for css_set objects
423 static inline void get_css_set(struct css_set
*cset
)
425 atomic_inc(&cset
->refcount
);
428 static inline void put_css_set(struct css_set
*cset
)
430 __put_css_set(cset
, 0);
433 static inline void put_css_set_taskexit(struct css_set
*cset
)
435 __put_css_set(cset
, 1);
439 * compare_css_sets - helper function for find_existing_css_set().
440 * @cset: candidate css_set being tested
441 * @old_cset: existing css_set for a task
442 * @new_cgrp: cgroup that's being entered by the task
443 * @template: desired set of css pointers in css_set (pre-calculated)
445 * Returns true if "cset" matches "old_cset" except for the hierarchy
446 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
448 static bool compare_css_sets(struct css_set
*cset
,
449 struct css_set
*old_cset
,
450 struct cgroup
*new_cgrp
,
451 struct cgroup_subsys_state
*template[])
453 struct list_head
*l1
, *l2
;
455 if (memcmp(template, cset
->subsys
, sizeof(cset
->subsys
))) {
456 /* Not all subsystems matched */
461 * Compare cgroup pointers in order to distinguish between
462 * different cgroups in heirarchies with no subsystems. We
463 * could get by with just this check alone (and skip the
464 * memcmp above) but on most setups the memcmp check will
465 * avoid the need for this more expensive check on almost all
469 l1
= &cset
->cgrp_links
;
470 l2
= &old_cset
->cgrp_links
;
472 struct cgrp_cset_link
*link1
, *link2
;
473 struct cgroup
*cgrp1
, *cgrp2
;
477 /* See if we reached the end - both lists are equal length. */
478 if (l1
== &cset
->cgrp_links
) {
479 BUG_ON(l2
!= &old_cset
->cgrp_links
);
482 BUG_ON(l2
== &old_cset
->cgrp_links
);
484 /* Locate the cgroups associated with these links. */
485 link1
= list_entry(l1
, struct cgrp_cset_link
, cgrp_link
);
486 link2
= list_entry(l2
, struct cgrp_cset_link
, cgrp_link
);
489 /* Hierarchies should be linked in the same order. */
490 BUG_ON(cgrp1
->root
!= cgrp2
->root
);
493 * If this hierarchy is the hierarchy of the cgroup
494 * that's changing, then we need to check that this
495 * css_set points to the new cgroup; if it's any other
496 * hierarchy, then this css_set should point to the
497 * same cgroup as the old css_set.
499 if (cgrp1
->root
== new_cgrp
->root
) {
500 if (cgrp1
!= new_cgrp
)
511 * find_existing_css_set - init css array and find the matching css_set
512 * @old_cset: the css_set that we're using before the cgroup transition
513 * @cgrp: the cgroup that we're moving into
514 * @template: out param for the new set of csses, should be clear on entry
516 static struct css_set
*find_existing_css_set(struct css_set
*old_cset
,
518 struct cgroup_subsys_state
*template[])
520 struct cgroupfs_root
*root
= cgrp
->root
;
521 struct cgroup_subsys
*ss
;
522 struct css_set
*cset
;
527 * Build the set of subsystem state objects that we want to see in the
528 * new css_set. while subsystems can change globally, the entries here
529 * won't change, so no need for locking.
531 for_each_subsys(ss
, i
) {
532 if (root
->subsys_mask
& (1UL << i
)) {
533 /* Subsystem is in this hierarchy. So we want
534 * the subsystem state from the new
536 template[i
] = cgroup_css(cgrp
, ss
);
538 /* Subsystem is not in this hierarchy, so we
539 * don't want to change the subsystem state */
540 template[i
] = old_cset
->subsys
[i
];
544 key
= css_set_hash(template);
545 hash_for_each_possible(css_set_table
, cset
, hlist
, key
) {
546 if (!compare_css_sets(cset
, old_cset
, cgrp
, template))
549 /* This css_set matches what we need */
553 /* No existing cgroup group matched */
557 static void free_cgrp_cset_links(struct list_head
*links_to_free
)
559 struct cgrp_cset_link
*link
, *tmp_link
;
561 list_for_each_entry_safe(link
, tmp_link
, links_to_free
, cset_link
) {
562 list_del(&link
->cset_link
);
568 * allocate_cgrp_cset_links - allocate cgrp_cset_links
569 * @count: the number of links to allocate
570 * @tmp_links: list_head the allocated links are put on
572 * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
573 * through ->cset_link. Returns 0 on success or -errno.
575 static int allocate_cgrp_cset_links(int count
, struct list_head
*tmp_links
)
577 struct cgrp_cset_link
*link
;
580 INIT_LIST_HEAD(tmp_links
);
582 for (i
= 0; i
< count
; i
++) {
583 link
= kzalloc(sizeof(*link
), GFP_KERNEL
);
585 free_cgrp_cset_links(tmp_links
);
588 list_add(&link
->cset_link
, tmp_links
);
594 * link_css_set - a helper function to link a css_set to a cgroup
595 * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
596 * @cset: the css_set to be linked
597 * @cgrp: the destination cgroup
599 static void link_css_set(struct list_head
*tmp_links
, struct css_set
*cset
,
602 struct cgrp_cset_link
*link
;
604 BUG_ON(list_empty(tmp_links
));
605 link
= list_first_entry(tmp_links
, struct cgrp_cset_link
, cset_link
);
608 list_move(&link
->cset_link
, &cgrp
->cset_links
);
610 * Always add links to the tail of the list so that the list
611 * is sorted by order of hierarchy creation
613 list_add_tail(&link
->cgrp_link
, &cset
->cgrp_links
);
617 * find_css_set - return a new css_set with one cgroup updated
618 * @old_cset: the baseline css_set
619 * @cgrp: the cgroup to be updated
621 * Return a new css_set that's equivalent to @old_cset, but with @cgrp
622 * substituted into the appropriate hierarchy.
624 static struct css_set
*find_css_set(struct css_set
*old_cset
,
627 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
] = { };
628 struct css_set
*cset
;
629 struct list_head tmp_links
;
630 struct cgrp_cset_link
*link
;
633 lockdep_assert_held(&cgroup_mutex
);
635 /* First see if we already have a cgroup group that matches
637 read_lock(&css_set_lock
);
638 cset
= find_existing_css_set(old_cset
, cgrp
, template);
641 read_unlock(&css_set_lock
);
646 cset
= kzalloc(sizeof(*cset
), GFP_KERNEL
);
650 /* Allocate all the cgrp_cset_link objects that we'll need */
651 if (allocate_cgrp_cset_links(cgroup_root_count
, &tmp_links
) < 0) {
656 atomic_set(&cset
->refcount
, 1);
657 INIT_LIST_HEAD(&cset
->cgrp_links
);
658 INIT_LIST_HEAD(&cset
->tasks
);
659 INIT_HLIST_NODE(&cset
->hlist
);
661 /* Copy the set of subsystem state objects generated in
662 * find_existing_css_set() */
663 memcpy(cset
->subsys
, template, sizeof(cset
->subsys
));
665 write_lock(&css_set_lock
);
666 /* Add reference counts and links from the new css_set. */
667 list_for_each_entry(link
, &old_cset
->cgrp_links
, cgrp_link
) {
668 struct cgroup
*c
= link
->cgrp
;
670 if (c
->root
== cgrp
->root
)
672 link_css_set(&tmp_links
, cset
, c
);
675 BUG_ON(!list_empty(&tmp_links
));
679 /* Add this cgroup group to the hash table */
680 key
= css_set_hash(cset
->subsys
);
681 hash_add(css_set_table
, &cset
->hlist
, key
);
683 write_unlock(&css_set_lock
);
688 static struct cgroupfs_root
*cgroup_root_from_kf(struct kernfs_root
*kf_root
)
690 struct cgroup
*top_cgrp
= kf_root
->kn
->priv
;
692 return top_cgrp
->root
;
695 static int cgroup_init_root_id(struct cgroupfs_root
*root
, int start
, int end
)
699 lockdep_assert_held(&cgroup_mutex
);
701 id
= idr_alloc_cyclic(&cgroup_hierarchy_idr
, root
, start
, end
,
706 root
->hierarchy_id
= id
;
710 static void cgroup_exit_root_id(struct cgroupfs_root
*root
)
712 lockdep_assert_held(&cgroup_mutex
);
714 if (root
->hierarchy_id
) {
715 idr_remove(&cgroup_hierarchy_idr
, root
->hierarchy_id
);
716 root
->hierarchy_id
= 0;
720 static void cgroup_free_root(struct cgroupfs_root
*root
)
723 /* hierarhcy ID shoulid already have been released */
724 WARN_ON_ONCE(root
->hierarchy_id
);
726 idr_destroy(&root
->cgroup_idr
);
731 static void cgroup_get_root(struct cgroupfs_root
*root
)
734 * The caller must ensure that @root is alive, which can be
735 * achieved by holding a ref on one of the member cgroups or
736 * following a registered reference to @root while holding
739 WARN_ON_ONCE(atomic_read(&root
->refcnt
) <= 0);
740 atomic_inc(&root
->refcnt
);
743 static void cgroup_put_root(struct cgroupfs_root
*root
)
745 struct cgroup
*cgrp
= &root
->top_cgroup
;
746 struct cgrp_cset_link
*link
, *tmp_link
;
750 * @root's refcnt reaching zero and its deregistration should be
751 * atomic w.r.t. cgroup_tree_mutex. This ensures that
752 * cgroup_get_root() is safe to invoke if @root is registered.
754 mutex_lock(&cgroup_tree_mutex
);
755 if (!atomic_dec_and_test(&root
->refcnt
)) {
756 mutex_unlock(&cgroup_tree_mutex
);
759 mutex_lock(&cgroup_mutex
);
761 BUG_ON(root
->number_of_cgroups
!= 1);
762 BUG_ON(!list_empty(&cgrp
->children
));
764 /* Rebind all subsystems back to the default hierarchy */
765 if (root
->flags
& CGRP_ROOT_SUBSYS_BOUND
) {
766 ret
= rebind_subsystems(root
, 0, root
->subsys_mask
);
767 /* Shouldn't be able to fail ... */
772 * Release all the links from cset_links to this hierarchy's
775 write_lock(&css_set_lock
);
777 list_for_each_entry_safe(link
, tmp_link
, &cgrp
->cset_links
, cset_link
) {
778 list_del(&link
->cset_link
);
779 list_del(&link
->cgrp_link
);
782 write_unlock(&css_set_lock
);
784 if (!list_empty(&root
->root_list
)) {
785 list_del(&root
->root_list
);
789 cgroup_exit_root_id(root
);
791 mutex_unlock(&cgroup_mutex
);
792 mutex_unlock(&cgroup_tree_mutex
);
794 kernfs_destroy_root(root
->kf_root
);
795 cgroup_free_root(root
);
799 * Return the cgroup for "task" from the given hierarchy. Must be
800 * called with cgroup_mutex held.
802 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
803 struct cgroupfs_root
*root
)
805 struct css_set
*cset
;
806 struct cgroup
*res
= NULL
;
808 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
809 read_lock(&css_set_lock
);
811 * No need to lock the task - since we hold cgroup_mutex the
812 * task can't change groups, so the only thing that can happen
813 * is that it exits and its css is set back to init_css_set.
815 cset
= task_css_set(task
);
816 if (cset
== &init_css_set
) {
817 res
= &root
->top_cgroup
;
819 struct cgrp_cset_link
*link
;
821 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
822 struct cgroup
*c
= link
->cgrp
;
824 if (c
->root
== root
) {
830 read_unlock(&css_set_lock
);
836 * There is one global cgroup mutex. We also require taking
837 * task_lock() when dereferencing a task's cgroup subsys pointers.
838 * See "The task_lock() exception", at the end of this comment.
840 * A task must hold cgroup_mutex to modify cgroups.
842 * Any task can increment and decrement the count field without lock.
843 * So in general, code holding cgroup_mutex can't rely on the count
844 * field not changing. However, if the count goes to zero, then only
845 * cgroup_attach_task() can increment it again. Because a count of zero
846 * means that no tasks are currently attached, therefore there is no
847 * way a task attached to that cgroup can fork (the other way to
848 * increment the count). So code holding cgroup_mutex can safely
849 * assume that if the count is zero, it will stay zero. Similarly, if
850 * a task holds cgroup_mutex on a cgroup with zero count, it
851 * knows that the cgroup won't be removed, as cgroup_rmdir()
854 * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
855 * (usually) take cgroup_mutex. These are the two most performance
856 * critical pieces of code here. The exception occurs on cgroup_exit(),
857 * when a task in a notify_on_release cgroup exits. Then cgroup_mutex
858 * is taken, and if the cgroup count is zero, a usermode call made
859 * to the release agent with the name of the cgroup (path relative to
860 * the root of cgroup file system) as the argument.
862 * A cgroup can only be deleted if both its 'count' of using tasks
863 * is zero, and its list of 'children' cgroups is empty. Since all
864 * tasks in the system use _some_ cgroup, and since there is always at
865 * least one task in the system (init, pid == 1), therefore, top_cgroup
866 * always has either children cgroups and/or using tasks. So we don't
867 * need a special hack to ensure that top_cgroup cannot be deleted.
869 * The task_lock() exception
871 * The need for this exception arises from the action of
872 * cgroup_attach_task(), which overwrites one task's cgroup pointer with
873 * another. It does so using cgroup_mutex, however there are
874 * several performance critical places that need to reference
875 * task->cgroup without the expense of grabbing a system global
876 * mutex. Therefore except as noted below, when dereferencing or, as
877 * in cgroup_attach_task(), modifying a task's cgroup pointer we use
878 * task_lock(), which acts on a spinlock (task->alloc_lock) already in
879 * the task_struct routinely used for such matters.
881 * P.S. One more locking exception. RCU is used to guard the
882 * update of a tasks cgroup pointer by cgroup_attach_task()
885 static int cgroup_populate_dir(struct cgroup
*cgrp
, unsigned long subsys_mask
);
886 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
;
887 static const struct file_operations proc_cgroupstats_operations
;
889 static char *cgroup_file_name(struct cgroup
*cgrp
, const struct cftype
*cft
,
892 if (cft
->ss
&& !(cft
->flags
& CFTYPE_NO_PREFIX
) &&
893 !(cgrp
->root
->flags
& CGRP_ROOT_NOPREFIX
))
894 snprintf(buf
, CGROUP_FILE_NAME_MAX
, "%s.%s",
895 cft
->ss
->name
, cft
->name
);
897 strncpy(buf
, cft
->name
, CGROUP_FILE_NAME_MAX
);
902 * cgroup_file_mode - deduce file mode of a control file
903 * @cft: the control file in question
905 * returns cft->mode if ->mode is not 0
906 * returns S_IRUGO|S_IWUSR if it has both a read and a write handler
907 * returns S_IRUGO if it has only a read handler
908 * returns S_IWUSR if it has only a write hander
910 static umode_t
cgroup_file_mode(const struct cftype
*cft
)
917 if (cft
->read_u64
|| cft
->read_s64
|| cft
->seq_show
)
920 if (cft
->write_u64
|| cft
->write_s64
|| cft
->write_string
||
927 static void cgroup_free_fn(struct work_struct
*work
)
929 struct cgroup
*cgrp
= container_of(work
, struct cgroup
, destroy_work
);
931 mutex_lock(&cgroup_mutex
);
932 cgrp
->root
->number_of_cgroups
--;
933 mutex_unlock(&cgroup_mutex
);
936 * We get a ref to the parent, and put the ref when this cgroup is
937 * being freed, so it's guaranteed that the parent won't be
938 * destroyed before its children.
940 cgroup_put(cgrp
->parent
);
942 /* put the root reference that we took when we created the cgroup */
943 cgroup_put_root(cgrp
->root
);
945 cgroup_pidlist_destroy_all(cgrp
);
947 kernfs_put(cgrp
->kn
);
951 static void cgroup_free_rcu(struct rcu_head
*head
)
953 struct cgroup
*cgrp
= container_of(head
, struct cgroup
, rcu_head
);
955 INIT_WORK(&cgrp
->destroy_work
, cgroup_free_fn
);
956 queue_work(cgroup_destroy_wq
, &cgrp
->destroy_work
);
959 static void cgroup_get(struct cgroup
*cgrp
)
961 WARN_ON_ONCE(cgroup_is_dead(cgrp
));
962 WARN_ON_ONCE(atomic_read(&cgrp
->refcnt
) <= 0);
963 atomic_inc(&cgrp
->refcnt
);
966 static void cgroup_put(struct cgroup
*cgrp
)
968 if (!atomic_dec_and_test(&cgrp
->refcnt
))
970 if (WARN_ON_ONCE(!cgroup_is_dead(cgrp
)))
974 * XXX: cgrp->id is only used to look up css's. As cgroup and
975 * css's lifetimes will be decoupled, it should be made
976 * per-subsystem and moved to css->id so that lookups are
977 * successful until the target css is released.
979 mutex_lock(&cgroup_mutex
);
980 idr_remove(&cgrp
->root
->cgroup_idr
, cgrp
->id
);
981 mutex_unlock(&cgroup_mutex
);
984 call_rcu(&cgrp
->rcu_head
, cgroup_free_rcu
);
987 static void cgroup_rm_file(struct cgroup
*cgrp
, const struct cftype
*cft
)
989 char name
[CGROUP_FILE_NAME_MAX
];
991 lockdep_assert_held(&cgroup_tree_mutex
);
992 kernfs_remove_by_name(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
));
996 * cgroup_clear_dir - remove subsys files in a cgroup directory
997 * @cgrp: target cgroup
998 * @subsys_mask: mask of the subsystem ids whose files should be removed
1000 static void cgroup_clear_dir(struct cgroup
*cgrp
, unsigned long subsys_mask
)
1002 struct cgroup_subsys
*ss
;
1005 for_each_subsys(ss
, i
) {
1006 struct cftype
*cfts
;
1008 if (!test_bit(i
, &subsys_mask
))
1010 list_for_each_entry(cfts
, &ss
->cfts
, node
)
1011 cgroup_addrm_files(cgrp
, cfts
, false);
1015 static int rebind_subsystems(struct cgroupfs_root
*root
,
1016 unsigned long added_mask
, unsigned removed_mask
)
1018 struct cgroup
*cgrp
= &root
->top_cgroup
;
1019 struct cgroup_subsys
*ss
;
1022 lockdep_assert_held(&cgroup_tree_mutex
);
1023 lockdep_assert_held(&cgroup_mutex
);
1025 /* Check that any added subsystems are currently free */
1026 for_each_subsys(ss
, i
)
1027 if ((added_mask
& (1 << i
)) && ss
->root
!= &cgroup_dummy_root
)
1030 ret
= cgroup_populate_dir(cgrp
, added_mask
);
1035 * Nothing can fail from this point on. Remove files for the
1036 * removed subsystems and rebind each subsystem.
1038 mutex_unlock(&cgroup_mutex
);
1039 cgroup_clear_dir(cgrp
, removed_mask
);
1040 mutex_lock(&cgroup_mutex
);
1042 for_each_subsys(ss
, i
) {
1043 unsigned long bit
= 1UL << i
;
1045 if (bit
& added_mask
) {
1046 /* We're binding this subsystem to this hierarchy */
1047 BUG_ON(cgroup_css(cgrp
, ss
));
1048 BUG_ON(!cgroup_css(cgroup_dummy_top
, ss
));
1049 BUG_ON(cgroup_css(cgroup_dummy_top
, ss
)->cgroup
!= cgroup_dummy_top
);
1051 rcu_assign_pointer(cgrp
->subsys
[i
],
1052 cgroup_css(cgroup_dummy_top
, ss
));
1053 cgroup_css(cgrp
, ss
)->cgroup
= cgrp
;
1057 ss
->bind(cgroup_css(cgrp
, ss
));
1059 /* refcount was already taken, and we're keeping it */
1060 root
->subsys_mask
|= bit
;
1061 } else if (bit
& removed_mask
) {
1062 /* We're removing this subsystem */
1063 BUG_ON(cgroup_css(cgrp
, ss
) != cgroup_css(cgroup_dummy_top
, ss
));
1064 BUG_ON(cgroup_css(cgrp
, ss
)->cgroup
!= cgrp
);
1067 ss
->bind(cgroup_css(cgroup_dummy_top
, ss
));
1069 cgroup_css(cgroup_dummy_top
, ss
)->cgroup
= cgroup_dummy_top
;
1070 RCU_INIT_POINTER(cgrp
->subsys
[i
], NULL
);
1072 cgroup_subsys
[i
]->root
= &cgroup_dummy_root
;
1073 root
->subsys_mask
&= ~bit
;
1078 * Mark @root has finished binding subsystems. @root->subsys_mask
1079 * now matches the bound subsystems.
1081 root
->flags
|= CGRP_ROOT_SUBSYS_BOUND
;
1082 kernfs_activate(cgrp
->kn
);
1087 static int cgroup_show_options(struct seq_file
*seq
,
1088 struct kernfs_root
*kf_root
)
1090 struct cgroupfs_root
*root
= cgroup_root_from_kf(kf_root
);
1091 struct cgroup_subsys
*ss
;
1094 for_each_subsys(ss
, ssid
)
1095 if (root
->subsys_mask
& (1 << ssid
))
1096 seq_printf(seq
, ",%s", ss
->name
);
1097 if (root
->flags
& CGRP_ROOT_SANE_BEHAVIOR
)
1098 seq_puts(seq
, ",sane_behavior");
1099 if (root
->flags
& CGRP_ROOT_NOPREFIX
)
1100 seq_puts(seq
, ",noprefix");
1101 if (root
->flags
& CGRP_ROOT_XATTR
)
1102 seq_puts(seq
, ",xattr");
1104 spin_lock(&release_agent_path_lock
);
1105 if (strlen(root
->release_agent_path
))
1106 seq_printf(seq
, ",release_agent=%s", root
->release_agent_path
);
1107 spin_unlock(&release_agent_path_lock
);
1109 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
))
1110 seq_puts(seq
, ",clone_children");
1111 if (strlen(root
->name
))
1112 seq_printf(seq
, ",name=%s", root
->name
);
1116 struct cgroup_sb_opts
{
1117 unsigned long subsys_mask
;
1118 unsigned long flags
;
1119 char *release_agent
;
1120 bool cpuset_clone_children
;
1122 /* User explicitly requested empty subsystem */
1127 * Convert a hierarchy specifier into a bitmask of subsystems and
1128 * flags. Call with cgroup_mutex held to protect the cgroup_subsys[]
1129 * array. This function takes refcounts on subsystems to be used, unless it
1130 * returns error, in which case no refcounts are taken.
1132 static int parse_cgroupfs_options(char *data
, struct cgroup_sb_opts
*opts
)
1134 char *token
, *o
= data
;
1135 bool all_ss
= false, one_ss
= false;
1136 unsigned long mask
= (unsigned long)-1;
1137 struct cgroup_subsys
*ss
;
1140 BUG_ON(!mutex_is_locked(&cgroup_mutex
));
1142 #ifdef CONFIG_CPUSETS
1143 mask
= ~(1UL << cpuset_cgrp_id
);
1146 memset(opts
, 0, sizeof(*opts
));
1148 while ((token
= strsep(&o
, ",")) != NULL
) {
1151 if (!strcmp(token
, "none")) {
1152 /* Explicitly have no subsystems */
1156 if (!strcmp(token
, "all")) {
1157 /* Mutually exclusive option 'all' + subsystem name */
1163 if (!strcmp(token
, "__DEVEL__sane_behavior")) {
1164 opts
->flags
|= CGRP_ROOT_SANE_BEHAVIOR
;
1167 if (!strcmp(token
, "noprefix")) {
1168 opts
->flags
|= CGRP_ROOT_NOPREFIX
;
1171 if (!strcmp(token
, "clone_children")) {
1172 opts
->cpuset_clone_children
= true;
1175 if (!strcmp(token
, "xattr")) {
1176 opts
->flags
|= CGRP_ROOT_XATTR
;
1179 if (!strncmp(token
, "release_agent=", 14)) {
1180 /* Specifying two release agents is forbidden */
1181 if (opts
->release_agent
)
1183 opts
->release_agent
=
1184 kstrndup(token
+ 14, PATH_MAX
- 1, GFP_KERNEL
);
1185 if (!opts
->release_agent
)
1189 if (!strncmp(token
, "name=", 5)) {
1190 const char *name
= token
+ 5;
1191 /* Can't specify an empty name */
1194 /* Must match [\w.-]+ */
1195 for (i
= 0; i
< strlen(name
); i
++) {
1199 if ((c
== '.') || (c
== '-') || (c
== '_'))
1203 /* Specifying two names is forbidden */
1206 opts
->name
= kstrndup(name
,
1207 MAX_CGROUP_ROOT_NAMELEN
- 1,
1215 for_each_subsys(ss
, i
) {
1216 if (strcmp(token
, ss
->name
))
1221 /* Mutually exclusive option 'all' + subsystem name */
1224 set_bit(i
, &opts
->subsys_mask
);
1229 if (i
== CGROUP_SUBSYS_COUNT
)
1234 * If the 'all' option was specified select all the subsystems,
1235 * otherwise if 'none', 'name=' and a subsystem name options
1236 * were not specified, let's default to 'all'
1238 if (all_ss
|| (!one_ss
&& !opts
->none
&& !opts
->name
))
1239 for_each_subsys(ss
, i
)
1241 set_bit(i
, &opts
->subsys_mask
);
1243 /* Consistency checks */
1245 if (opts
->flags
& CGRP_ROOT_SANE_BEHAVIOR
) {
1246 pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
1248 if (opts
->flags
& CGRP_ROOT_NOPREFIX
) {
1249 pr_err("cgroup: sane_behavior: noprefix is not allowed\n");
1253 if (opts
->cpuset_clone_children
) {
1254 pr_err("cgroup: sane_behavior: clone_children is not allowed\n");
1258 if (opts
->flags
& CGRP_ROOT_XATTR
)
1259 pr_warning("cgroup: sane_behavior: xattr is always available, flag unnecessary\n");
1263 * Option noprefix was introduced just for backward compatibility
1264 * with the old cpuset, so we allow noprefix only if mounting just
1265 * the cpuset subsystem.
1267 if ((opts
->flags
& CGRP_ROOT_NOPREFIX
) && (opts
->subsys_mask
& mask
))
1271 /* Can't specify "none" and some subsystems */
1272 if (opts
->subsys_mask
&& opts
->none
)
1276 * We either have to specify by name or by subsystems. (So all
1277 * empty hierarchies must have a name).
1279 if (!opts
->subsys_mask
&& !opts
->name
)
1285 static int cgroup_remount(struct kernfs_root
*kf_root
, int *flags
, char *data
)
1288 struct cgroupfs_root
*root
= cgroup_root_from_kf(kf_root
);
1289 struct cgroup_sb_opts opts
;
1290 unsigned long added_mask
, removed_mask
;
1292 if (root
->flags
& CGRP_ROOT_SANE_BEHAVIOR
) {
1293 pr_err("cgroup: sane_behavior: remount is not allowed\n");
1297 mutex_lock(&cgroup_tree_mutex
);
1298 mutex_lock(&cgroup_mutex
);
1300 /* See what subsystems are wanted */
1301 ret
= parse_cgroupfs_options(data
, &opts
);
1305 if (opts
.subsys_mask
!= root
->subsys_mask
|| opts
.release_agent
)
1306 pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
1307 task_tgid_nr(current
), current
->comm
);
1309 added_mask
= opts
.subsys_mask
& ~root
->subsys_mask
;
1310 removed_mask
= root
->subsys_mask
& ~opts
.subsys_mask
;
1312 /* Don't allow flags or name to change at remount */
1313 if (((opts
.flags
^ root
->flags
) & CGRP_ROOT_OPTION_MASK
) ||
1314 (opts
.name
&& strcmp(opts
.name
, root
->name
))) {
1315 pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n",
1316 opts
.flags
& CGRP_ROOT_OPTION_MASK
, opts
.name
?: "",
1317 root
->flags
& CGRP_ROOT_OPTION_MASK
, root
->name
);
1322 /* remounting is not allowed for populated hierarchies */
1323 if (root
->number_of_cgroups
> 1) {
1328 ret
= rebind_subsystems(root
, added_mask
, removed_mask
);
1332 if (opts
.release_agent
) {
1333 spin_lock(&release_agent_path_lock
);
1334 strcpy(root
->release_agent_path
, opts
.release_agent
);
1335 spin_unlock(&release_agent_path_lock
);
1338 kfree(opts
.release_agent
);
1340 mutex_unlock(&cgroup_mutex
);
1341 mutex_unlock(&cgroup_tree_mutex
);
1345 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1347 atomic_set(&cgrp
->refcnt
, 1);
1348 INIT_LIST_HEAD(&cgrp
->sibling
);
1349 INIT_LIST_HEAD(&cgrp
->children
);
1350 INIT_LIST_HEAD(&cgrp
->cset_links
);
1351 INIT_LIST_HEAD(&cgrp
->release_list
);
1352 INIT_LIST_HEAD(&cgrp
->pidlists
);
1353 mutex_init(&cgrp
->pidlist_mutex
);
1354 cgrp
->dummy_css
.cgroup
= cgrp
;
1357 static void init_cgroup_root(struct cgroupfs_root
*root
)
1359 struct cgroup
*cgrp
= &root
->top_cgroup
;
1361 atomic_set(&root
->refcnt
, 1);
1362 INIT_LIST_HEAD(&root
->root_list
);
1363 root
->number_of_cgroups
= 1;
1365 init_cgroup_housekeeping(cgrp
);
1366 idr_init(&root
->cgroup_idr
);
1369 static struct cgroupfs_root
*cgroup_root_from_opts(struct cgroup_sb_opts
*opts
)
1371 struct cgroupfs_root
*root
;
1373 if (!opts
->subsys_mask
&& !opts
->none
)
1374 return ERR_PTR(-EINVAL
);
1376 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
1378 return ERR_PTR(-ENOMEM
);
1380 init_cgroup_root(root
);
1383 * We need to set @root->subsys_mask now so that @root can be
1384 * matched by cgroup_test_super() before it finishes
1385 * initialization; otherwise, competing mounts with the same
1386 * options may try to bind the same subsystems instead of waiting
1387 * for the first one leading to unexpected mount errors.
1388 * SUBSYS_BOUND will be set once actual binding is complete.
1390 root
->subsys_mask
= opts
->subsys_mask
;
1391 root
->flags
= opts
->flags
;
1392 if (opts
->release_agent
)
1393 strcpy(root
->release_agent_path
, opts
->release_agent
);
1395 strcpy(root
->name
, opts
->name
);
1396 if (opts
->cpuset_clone_children
)
1397 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->top_cgroup
.flags
);
1401 static int cgroup_setup_root(struct cgroupfs_root
*root
)
1403 LIST_HEAD(tmp_links
);
1404 struct cgroup
*root_cgrp
= &root
->top_cgroup
;
1405 struct css_set
*cset
;
1408 lockdep_assert_held(&cgroup_tree_mutex
);
1409 lockdep_assert_held(&cgroup_mutex
);
1411 ret
= idr_alloc(&root
->cgroup_idr
, root_cgrp
, 0, 1, GFP_KERNEL
);
1414 root_cgrp
->id
= ret
;
1417 * We're accessing css_set_count without locking css_set_lock here,
1418 * but that's OK - it can only be increased by someone holding
1419 * cgroup_lock, and that's us. The worst that can happen is that we
1420 * have some link structures left over
1422 ret
= allocate_cgrp_cset_links(css_set_count
, &tmp_links
);
1426 /* ID 0 is reserved for dummy root, 1 for unified hierarchy */
1427 ret
= cgroup_init_root_id(root
, 2, 0);
1431 root
->kf_root
= kernfs_create_root(&cgroup_kf_syscall_ops
,
1432 KERNFS_ROOT_CREATE_DEACTIVATED
,
1434 if (IS_ERR(root
->kf_root
)) {
1435 ret
= PTR_ERR(root
->kf_root
);
1438 root_cgrp
->kn
= root
->kf_root
->kn
;
1440 ret
= cgroup_addrm_files(root_cgrp
, cgroup_base_files
, true);
1444 ret
= rebind_subsystems(root
, root
->subsys_mask
, 0);
1449 * There must be no failure case after here, since rebinding takes
1450 * care of subsystems' refcounts, which are explicitly dropped in
1451 * the failure exit path.
1453 list_add(&root
->root_list
, &cgroup_roots
);
1454 cgroup_root_count
++;
1457 * Link the top cgroup in this hierarchy into all the css_set
1460 write_lock(&css_set_lock
);
1461 hash_for_each(css_set_table
, i
, cset
, hlist
)
1462 link_css_set(&tmp_links
, cset
, root_cgrp
);
1463 write_unlock(&css_set_lock
);
1465 BUG_ON(!list_empty(&root_cgrp
->children
));
1466 BUG_ON(root
->number_of_cgroups
!= 1);
1468 kernfs_activate(root_cgrp
->kn
);
1473 kernfs_destroy_root(root
->kf_root
);
1474 root
->kf_root
= NULL
;
1476 cgroup_exit_root_id(root
);
1478 free_cgrp_cset_links(&tmp_links
);
1482 static struct dentry
*cgroup_mount(struct file_system_type
*fs_type
,
1483 int flags
, const char *unused_dev_name
,
1486 struct cgroupfs_root
*root
;
1487 struct cgroup_sb_opts opts
;
1488 struct dentry
*dentry
;
1491 mutex_lock(&cgroup_tree_mutex
);
1492 mutex_lock(&cgroup_mutex
);
1494 /* First find the desired set of subsystems */
1495 ret
= parse_cgroupfs_options(data
, &opts
);
1499 /* look for a matching existing root */
1500 for_each_active_root(root
) {
1501 bool name_match
= false;
1504 * If we asked for a name then it must match. Also, if
1505 * name matches but sybsys_mask doesn't, we should fail.
1506 * Remember whether name matched.
1509 if (strcmp(opts
.name
, root
->name
))
1515 * If we asked for subsystems (or explicitly for no
1516 * subsystems) then they must match.
1518 if ((opts
.subsys_mask
|| opts
.none
) &&
1519 (opts
.subsys_mask
!= root
->subsys_mask
)) {
1526 if ((root
->flags
^ opts
.flags
) & CGRP_ROOT_OPTION_MASK
) {
1527 if ((root
->flags
| opts
.flags
) & CGRP_ROOT_SANE_BEHAVIOR
) {
1528 pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
1532 pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
1536 cgroup_get_root(root
);
1540 /* no such thing, create a new one */
1541 root
= cgroup_root_from_opts(&opts
);
1543 ret
= PTR_ERR(root
);
1547 ret
= cgroup_setup_root(root
);
1549 cgroup_free_root(root
);
1552 mutex_unlock(&cgroup_mutex
);
1553 mutex_unlock(&cgroup_tree_mutex
);
1555 kfree(opts
.release_agent
);
1559 return ERR_PTR(ret
);
1561 dentry
= kernfs_mount(fs_type
, flags
, root
->kf_root
);
1563 cgroup_put_root(root
);
1567 static void cgroup_kill_sb(struct super_block
*sb
)
1569 struct kernfs_root
*kf_root
= kernfs_root_from_sb(sb
);
1570 struct cgroupfs_root
*root
= cgroup_root_from_kf(kf_root
);
1572 cgroup_put_root(root
);
1576 static struct file_system_type cgroup_fs_type
= {
1578 .mount
= cgroup_mount
,
1579 .kill_sb
= cgroup_kill_sb
,
1582 static struct kobject
*cgroup_kobj
;
1585 * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
1586 * @task: target task
1587 * @buf: the buffer to write the path into
1588 * @buflen: the length of the buffer
1590 * Determine @task's cgroup on the first (the one with the lowest non-zero
1591 * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
1592 * function grabs cgroup_mutex and shouldn't be used inside locks used by
1593 * cgroup controller callbacks.
1595 * Return value is the same as kernfs_path().
1597 char *task_cgroup_path(struct task_struct
*task
, char *buf
, size_t buflen
)
1599 struct cgroupfs_root
*root
;
1600 struct cgroup
*cgrp
;
1601 int hierarchy_id
= 1;
1604 mutex_lock(&cgroup_mutex
);
1606 root
= idr_get_next(&cgroup_hierarchy_idr
, &hierarchy_id
);
1609 cgrp
= task_cgroup_from_root(task
, root
);
1610 path
= cgroup_path(cgrp
, buf
, buflen
);
1612 /* if no hierarchy exists, everyone is in "/" */
1613 if (strlcpy(buf
, "/", buflen
) < buflen
)
1617 mutex_unlock(&cgroup_mutex
);
1620 EXPORT_SYMBOL_GPL(task_cgroup_path
);
1623 * Control Group taskset
1625 struct task_and_cgroup
{
1626 struct task_struct
*task
;
1627 struct cgroup
*cgrp
;
1628 struct css_set
*cset
;
1631 struct cgroup_taskset
{
1632 struct task_and_cgroup single
;
1633 struct flex_array
*tc_array
;
1636 struct cgroup
*cur_cgrp
;
1640 * cgroup_taskset_first - reset taskset and return the first task
1641 * @tset: taskset of interest
1643 * @tset iteration is initialized and the first task is returned.
1645 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
)
1647 if (tset
->tc_array
) {
1649 return cgroup_taskset_next(tset
);
1651 tset
->cur_cgrp
= tset
->single
.cgrp
;
1652 return tset
->single
.task
;
1655 EXPORT_SYMBOL_GPL(cgroup_taskset_first
);
1658 * cgroup_taskset_next - iterate to the next task in taskset
1659 * @tset: taskset of interest
1661 * Return the next task in @tset. Iteration must have been initialized
1662 * with cgroup_taskset_first().
1664 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
)
1666 struct task_and_cgroup
*tc
;
1668 if (!tset
->tc_array
|| tset
->idx
>= tset
->tc_array_len
)
1671 tc
= flex_array_get(tset
->tc_array
, tset
->idx
++);
1672 tset
->cur_cgrp
= tc
->cgrp
;
1675 EXPORT_SYMBOL_GPL(cgroup_taskset_next
);
1678 * cgroup_taskset_cur_css - return the matching css for the current task
1679 * @tset: taskset of interest
1680 * @subsys_id: the ID of the target subsystem
1682 * Return the css for the current (last returned) task of @tset for
1683 * subsystem specified by @subsys_id. This function must be preceded by
1684 * either cgroup_taskset_first() or cgroup_taskset_next().
1686 struct cgroup_subsys_state
*cgroup_taskset_cur_css(struct cgroup_taskset
*tset
,
1689 return cgroup_css(tset
->cur_cgrp
, cgroup_subsys
[subsys_id
]);
1691 EXPORT_SYMBOL_GPL(cgroup_taskset_cur_css
);
1694 * cgroup_taskset_size - return the number of tasks in taskset
1695 * @tset: taskset of interest
1697 int cgroup_taskset_size(struct cgroup_taskset
*tset
)
1699 return tset
->tc_array
? tset
->tc_array_len
: 1;
1701 EXPORT_SYMBOL_GPL(cgroup_taskset_size
);
1705 * cgroup_task_migrate - move a task from one cgroup to another.
1707 * Must be called with cgroup_mutex and threadgroup locked.
1709 static void cgroup_task_migrate(struct cgroup
*old_cgrp
,
1710 struct task_struct
*tsk
,
1711 struct css_set
*new_cset
)
1713 struct css_set
*old_cset
;
1716 * We are synchronized through threadgroup_lock() against PF_EXITING
1717 * setting such that we can't race against cgroup_exit() changing the
1718 * css_set to init_css_set and dropping the old one.
1720 WARN_ON_ONCE(tsk
->flags
& PF_EXITING
);
1721 old_cset
= task_css_set(tsk
);
1724 rcu_assign_pointer(tsk
->cgroups
, new_cset
);
1727 /* Update the css_set linked lists if we're using them */
1728 write_lock(&css_set_lock
);
1729 if (!list_empty(&tsk
->cg_list
))
1730 list_move(&tsk
->cg_list
, &new_cset
->tasks
);
1731 write_unlock(&css_set_lock
);
1734 * We just gained a reference on old_cset by taking it from the
1735 * task. As trading it for new_cset is protected by cgroup_mutex,
1736 * we're safe to drop it here; it will be freed under RCU.
1738 set_bit(CGRP_RELEASABLE
, &old_cgrp
->flags
);
1739 put_css_set(old_cset
);
1743 * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
1744 * @cgrp: the cgroup to attach to
1745 * @tsk: the task or the leader of the threadgroup to be attached
1746 * @threadgroup: attach the whole threadgroup?
1748 * Call holding cgroup_mutex and the group_rwsem of the leader. Will take
1749 * task_lock of @tsk or each thread in the threadgroup individually in turn.
1751 static int cgroup_attach_task(struct cgroup
*cgrp
, struct task_struct
*tsk
,
1754 int retval
, i
, group_size
;
1755 struct cgroupfs_root
*root
= cgrp
->root
;
1756 struct cgroup_subsys_state
*css
, *failed_css
= NULL
;
1757 /* threadgroup list cursor and array */
1758 struct task_struct
*leader
= tsk
;
1759 struct task_and_cgroup
*tc
;
1760 struct flex_array
*group
;
1761 struct cgroup_taskset tset
= { };
1764 * step 0: in order to do expensive, possibly blocking operations for
1765 * every thread, we cannot iterate the thread group list, since it needs
1766 * rcu or tasklist locked. instead, build an array of all threads in the
1767 * group - group_rwsem prevents new threads from appearing, and if
1768 * threads exit, this will just be an over-estimate.
1771 group_size
= get_nr_threads(tsk
);
1774 /* flex_array supports very large thread-groups better than kmalloc. */
1775 group
= flex_array_alloc(sizeof(*tc
), group_size
, GFP_KERNEL
);
1778 /* pre-allocate to guarantee space while iterating in rcu read-side. */
1779 retval
= flex_array_prealloc(group
, 0, group_size
, GFP_KERNEL
);
1781 goto out_free_group_list
;
1785 * Prevent freeing of tasks while we take a snapshot. Tasks that are
1786 * already PF_EXITING could be freed from underneath us unless we
1787 * take an rcu_read_lock.
1791 struct task_and_cgroup ent
;
1793 /* @tsk either already exited or can't exit until the end */
1794 if (tsk
->flags
& PF_EXITING
)
1797 /* as per above, nr_threads may decrease, but not increase. */
1798 BUG_ON(i
>= group_size
);
1800 ent
.cgrp
= task_cgroup_from_root(tsk
, root
);
1801 /* nothing to do if this task is already in the cgroup */
1802 if (ent
.cgrp
== cgrp
)
1805 * saying GFP_ATOMIC has no effect here because we did prealloc
1806 * earlier, but it's good form to communicate our expectations.
1808 retval
= flex_array_put(group
, i
, &ent
, GFP_ATOMIC
);
1809 BUG_ON(retval
!= 0);
1814 } while_each_thread(leader
, tsk
);
1816 /* remember the number of threads in the array for later. */
1818 tset
.tc_array
= group
;
1819 tset
.tc_array_len
= group_size
;
1821 /* methods shouldn't be called if no task is actually migrating */
1824 goto out_free_group_list
;
1827 * step 1: check that we can legitimately attach to the cgroup.
1829 for_each_css(css
, i
, cgrp
) {
1830 if (css
->ss
->can_attach
) {
1831 retval
= css
->ss
->can_attach(css
, &tset
);
1834 goto out_cancel_attach
;
1840 * step 2: make sure css_sets exist for all threads to be migrated.
1841 * we use find_css_set, which allocates a new one if necessary.
1843 for (i
= 0; i
< group_size
; i
++) {
1844 struct css_set
*old_cset
;
1846 tc
= flex_array_get(group
, i
);
1847 old_cset
= task_css_set(tc
->task
);
1848 tc
->cset
= find_css_set(old_cset
, cgrp
);
1851 goto out_put_css_set_refs
;
1856 * step 3: now that we're guaranteed success wrt the css_sets,
1857 * proceed to move all tasks to the new cgroup. There are no
1858 * failure cases after here, so this is the commit point.
1860 for (i
= 0; i
< group_size
; i
++) {
1861 tc
= flex_array_get(group
, i
);
1862 cgroup_task_migrate(tc
->cgrp
, tc
->task
, tc
->cset
);
1864 /* nothing is sensitive to fork() after this point. */
1867 * step 4: do subsystem attach callbacks.
1869 for_each_css(css
, i
, cgrp
)
1870 if (css
->ss
->attach
)
1871 css
->ss
->attach(css
, &tset
);
1874 * step 5: success! and cleanup
1877 out_put_css_set_refs
:
1879 for (i
= 0; i
< group_size
; i
++) {
1880 tc
= flex_array_get(group
, i
);
1883 put_css_set(tc
->cset
);
1888 for_each_css(css
, i
, cgrp
) {
1889 if (css
== failed_css
)
1891 if (css
->ss
->cancel_attach
)
1892 css
->ss
->cancel_attach(css
, &tset
);
1895 out_free_group_list
:
1896 flex_array_free(group
);
1901 * Find the task_struct of the task to attach by vpid and pass it along to the
1902 * function to attach either it or all tasks in its threadgroup. Will lock
1903 * cgroup_mutex and threadgroup; may take task_lock of task.
1905 static int attach_task_by_pid(struct cgroup
*cgrp
, u64 pid
, bool threadgroup
)
1907 struct task_struct
*tsk
;
1908 const struct cred
*cred
= current_cred(), *tcred
;
1911 if (!cgroup_lock_live_group(cgrp
))
1917 tsk
= find_task_by_vpid(pid
);
1921 goto out_unlock_cgroup
;
1924 * even if we're attaching all tasks in the thread group, we
1925 * only need to check permissions on one of them.
1927 tcred
= __task_cred(tsk
);
1928 if (!uid_eq(cred
->euid
, GLOBAL_ROOT_UID
) &&
1929 !uid_eq(cred
->euid
, tcred
->uid
) &&
1930 !uid_eq(cred
->euid
, tcred
->suid
)) {
1933 goto out_unlock_cgroup
;
1939 tsk
= tsk
->group_leader
;
1942 * Workqueue threads may acquire PF_NO_SETAFFINITY and become
1943 * trapped in a cpuset, or RT worker may be born in a cgroup
1944 * with no rt_runtime allocated. Just say no.
1946 if (tsk
== kthreadd_task
|| (tsk
->flags
& PF_NO_SETAFFINITY
)) {
1949 goto out_unlock_cgroup
;
1952 get_task_struct(tsk
);
1955 threadgroup_lock(tsk
);
1957 if (!thread_group_leader(tsk
)) {
1959 * a race with de_thread from another thread's exec()
1960 * may strip us of our leadership, if this happens,
1961 * there is no choice but to throw this task away and
1962 * try again; this is
1963 * "double-double-toil-and-trouble-check locking".
1965 threadgroup_unlock(tsk
);
1966 put_task_struct(tsk
);
1967 goto retry_find_task
;
1971 ret
= cgroup_attach_task(cgrp
, tsk
, threadgroup
);
1973 threadgroup_unlock(tsk
);
1975 put_task_struct(tsk
);
1977 mutex_unlock(&cgroup_mutex
);
1982 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
1983 * @from: attach to all cgroups of a given task
1984 * @tsk: the task to be attached
1986 int cgroup_attach_task_all(struct task_struct
*from
, struct task_struct
*tsk
)
1988 struct cgroupfs_root
*root
;
1991 mutex_lock(&cgroup_mutex
);
1992 for_each_active_root(root
) {
1993 struct cgroup
*from_cgrp
= task_cgroup_from_root(from
, root
);
1995 retval
= cgroup_attach_task(from_cgrp
, tsk
, false);
1999 mutex_unlock(&cgroup_mutex
);
2003 EXPORT_SYMBOL_GPL(cgroup_attach_task_all
);
2005 static int cgroup_tasks_write(struct cgroup_subsys_state
*css
,
2006 struct cftype
*cft
, u64 pid
)
2008 return attach_task_by_pid(css
->cgroup
, pid
, false);
2011 static int cgroup_procs_write(struct cgroup_subsys_state
*css
,
2012 struct cftype
*cft
, u64 tgid
)
2014 return attach_task_by_pid(css
->cgroup
, tgid
, true);
2017 static int cgroup_release_agent_write(struct cgroup_subsys_state
*css
,
2018 struct cftype
*cft
, const char *buffer
)
2020 struct cgroupfs_root
*root
= css
->cgroup
->root
;
2022 BUILD_BUG_ON(sizeof(root
->release_agent_path
) < PATH_MAX
);
2023 if (!cgroup_lock_live_group(css
->cgroup
))
2025 spin_lock(&release_agent_path_lock
);
2026 strlcpy(root
->release_agent_path
, buffer
,
2027 sizeof(root
->release_agent_path
));
2028 spin_unlock(&release_agent_path_lock
);
2029 mutex_unlock(&cgroup_mutex
);
2033 static int cgroup_release_agent_show(struct seq_file
*seq
, void *v
)
2035 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
2037 if (!cgroup_lock_live_group(cgrp
))
2039 seq_puts(seq
, cgrp
->root
->release_agent_path
);
2040 seq_putc(seq
, '\n');
2041 mutex_unlock(&cgroup_mutex
);
2045 static int cgroup_sane_behavior_show(struct seq_file
*seq
, void *v
)
2047 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
2049 seq_printf(seq
, "%d\n", cgroup_sane_behavior(cgrp
));
2053 static ssize_t
cgroup_file_write(struct kernfs_open_file
*of
, char *buf
,
2054 size_t nbytes
, loff_t off
)
2056 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
2057 struct cftype
*cft
= of
->kn
->priv
;
2058 struct cgroup_subsys_state
*css
;
2062 * kernfs guarantees that a file isn't deleted with operations in
2063 * flight, which means that the matching css is and stays alive and
2064 * doesn't need to be pinned. The RCU locking is not necessary
2065 * either. It's just for the convenience of using cgroup_css().
2068 css
= cgroup_css(cgrp
, cft
->ss
);
2071 if (cft
->write_string
) {
2072 ret
= cft
->write_string(css
, cft
, strstrip(buf
));
2073 } else if (cft
->write_u64
) {
2074 unsigned long long v
;
2075 ret
= kstrtoull(buf
, 0, &v
);
2077 ret
= cft
->write_u64(css
, cft
, v
);
2078 } else if (cft
->write_s64
) {
2080 ret
= kstrtoll(buf
, 0, &v
);
2082 ret
= cft
->write_s64(css
, cft
, v
);
2083 } else if (cft
->trigger
) {
2084 ret
= cft
->trigger(css
, (unsigned int)cft
->private);
2089 return ret
?: nbytes
;
2092 static void *cgroup_seqfile_start(struct seq_file
*seq
, loff_t
*ppos
)
2094 return seq_cft(seq
)->seq_start(seq
, ppos
);
2097 static void *cgroup_seqfile_next(struct seq_file
*seq
, void *v
, loff_t
*ppos
)
2099 return seq_cft(seq
)->seq_next(seq
, v
, ppos
);
2102 static void cgroup_seqfile_stop(struct seq_file
*seq
, void *v
)
2104 seq_cft(seq
)->seq_stop(seq
, v
);
2107 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
2109 struct cftype
*cft
= seq_cft(m
);
2110 struct cgroup_subsys_state
*css
= seq_css(m
);
2113 return cft
->seq_show(m
, arg
);
2116 seq_printf(m
, "%llu\n", cft
->read_u64(css
, cft
));
2117 else if (cft
->read_s64
)
2118 seq_printf(m
, "%lld\n", cft
->read_s64(css
, cft
));
2124 static struct kernfs_ops cgroup_kf_single_ops
= {
2125 .atomic_write_len
= PAGE_SIZE
,
2126 .write
= cgroup_file_write
,
2127 .seq_show
= cgroup_seqfile_show
,
2130 static struct kernfs_ops cgroup_kf_ops
= {
2131 .atomic_write_len
= PAGE_SIZE
,
2132 .write
= cgroup_file_write
,
2133 .seq_start
= cgroup_seqfile_start
,
2134 .seq_next
= cgroup_seqfile_next
,
2135 .seq_stop
= cgroup_seqfile_stop
,
2136 .seq_show
= cgroup_seqfile_show
,
2140 * cgroup_rename - Only allow simple rename of directories in place.
2142 static int cgroup_rename(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
2143 const char *new_name_str
)
2145 struct cgroup
*cgrp
= kn
->priv
;
2148 if (kernfs_type(kn
) != KERNFS_DIR
)
2150 if (kn
->parent
!= new_parent
)
2154 * This isn't a proper migration and its usefulness is very
2155 * limited. Disallow if sane_behavior.
2157 if (cgroup_sane_behavior(cgrp
))
2160 mutex_lock(&cgroup_tree_mutex
);
2161 mutex_lock(&cgroup_mutex
);
2163 ret
= kernfs_rename(kn
, new_parent
, new_name_str
);
2165 mutex_unlock(&cgroup_mutex
);
2166 mutex_unlock(&cgroup_tree_mutex
);
2170 static int cgroup_add_file(struct cgroup
*cgrp
, struct cftype
*cft
)
2172 char name
[CGROUP_FILE_NAME_MAX
];
2173 struct kernfs_node
*kn
;
2174 struct lock_class_key
*key
= NULL
;
2176 #ifdef CONFIG_DEBUG_LOCK_ALLOC
2177 key
= &cft
->lockdep_key
;
2179 kn
= __kernfs_create_file(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
),
2180 cgroup_file_mode(cft
), 0, cft
->kf_ops
, cft
,
2188 * cgroup_addrm_files - add or remove files to a cgroup directory
2189 * @cgrp: the target cgroup
2190 * @cfts: array of cftypes to be added
2191 * @is_add: whether to add or remove
2193 * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
2194 * For removals, this function never fails. If addition fails, this
2195 * function doesn't remove files already added. The caller is responsible
2198 static int cgroup_addrm_files(struct cgroup
*cgrp
, struct cftype cfts
[],
2204 lockdep_assert_held(&cgroup_tree_mutex
);
2206 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
2207 /* does cft->flags tell us to skip this file on @cgrp? */
2208 if ((cft
->flags
& CFTYPE_INSANE
) && cgroup_sane_behavior(cgrp
))
2210 if ((cft
->flags
& CFTYPE_NOT_ON_ROOT
) && !cgrp
->parent
)
2212 if ((cft
->flags
& CFTYPE_ONLY_ON_ROOT
) && cgrp
->parent
)
2216 ret
= cgroup_add_file(cgrp
, cft
);
2218 pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
2223 cgroup_rm_file(cgrp
, cft
);
2229 static int cgroup_apply_cftypes(struct cftype
*cfts
, bool is_add
)
2232 struct cgroup_subsys
*ss
= cfts
[0].ss
;
2233 struct cgroup
*root
= &ss
->root
->top_cgroup
;
2234 struct cgroup_subsys_state
*css
;
2237 lockdep_assert_held(&cgroup_tree_mutex
);
2239 /* don't bother if @ss isn't attached */
2240 if (ss
->root
== &cgroup_dummy_root
)
2243 /* add/rm files for all cgroups created before */
2244 css_for_each_descendant_pre(css
, cgroup_css(root
, ss
)) {
2245 struct cgroup
*cgrp
= css
->cgroup
;
2247 if (cgroup_is_dead(cgrp
))
2250 ret
= cgroup_addrm_files(cgrp
, cfts
, is_add
);
2256 kernfs_activate(root
->kn
);
2260 static void cgroup_exit_cftypes(struct cftype
*cfts
)
2264 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
2265 /* free copy for custom atomic_write_len, see init_cftypes() */
2266 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
)
2273 static int cgroup_init_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2277 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
2278 struct kernfs_ops
*kf_ops
;
2280 WARN_ON(cft
->ss
|| cft
->kf_ops
);
2283 kf_ops
= &cgroup_kf_ops
;
2285 kf_ops
= &cgroup_kf_single_ops
;
2288 * Ugh... if @cft wants a custom max_write_len, we need to
2289 * make a copy of kf_ops to set its atomic_write_len.
2291 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
) {
2292 kf_ops
= kmemdup(kf_ops
, sizeof(*kf_ops
), GFP_KERNEL
);
2294 cgroup_exit_cftypes(cfts
);
2297 kf_ops
->atomic_write_len
= cft
->max_write_len
;
2300 cft
->kf_ops
= kf_ops
;
2307 static int cgroup_rm_cftypes_locked(struct cftype
*cfts
)
2309 lockdep_assert_held(&cgroup_tree_mutex
);
2311 if (!cfts
|| !cfts
[0].ss
)
2314 list_del(&cfts
->node
);
2315 cgroup_apply_cftypes(cfts
, false);
2316 cgroup_exit_cftypes(cfts
);
2321 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
2322 * @cfts: zero-length name terminated array of cftypes
2324 * Unregister @cfts. Files described by @cfts are removed from all
2325 * existing cgroups and all future cgroups won't have them either. This
2326 * function can be called anytime whether @cfts' subsys is attached or not.
2328 * Returns 0 on successful unregistration, -ENOENT if @cfts is not
2331 int cgroup_rm_cftypes(struct cftype
*cfts
)
2335 mutex_lock(&cgroup_tree_mutex
);
2336 ret
= cgroup_rm_cftypes_locked(cfts
);
2337 mutex_unlock(&cgroup_tree_mutex
);
2342 * cgroup_add_cftypes - add an array of cftypes to a subsystem
2343 * @ss: target cgroup subsystem
2344 * @cfts: zero-length name terminated array of cftypes
2346 * Register @cfts to @ss. Files described by @cfts are created for all
2347 * existing cgroups to which @ss is attached and all future cgroups will
2348 * have them too. This function can be called anytime whether @ss is
2351 * Returns 0 on successful registration, -errno on failure. Note that this
2352 * function currently returns 0 as long as @cfts registration is successful
2353 * even if some file creation attempts on existing cgroups fail.
2355 int cgroup_add_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
2359 ret
= cgroup_init_cftypes(ss
, cfts
);
2363 mutex_lock(&cgroup_tree_mutex
);
2365 list_add_tail(&cfts
->node
, &ss
->cfts
);
2366 ret
= cgroup_apply_cftypes(cfts
, true);
2368 cgroup_rm_cftypes_locked(cfts
);
2370 mutex_unlock(&cgroup_tree_mutex
);
2373 EXPORT_SYMBOL_GPL(cgroup_add_cftypes
);
2376 * cgroup_task_count - count the number of tasks in a cgroup.
2377 * @cgrp: the cgroup in question
2379 * Return the number of tasks in the cgroup.
2381 int cgroup_task_count(const struct cgroup
*cgrp
)
2384 struct cgrp_cset_link
*link
;
2386 read_lock(&css_set_lock
);
2387 list_for_each_entry(link
, &cgrp
->cset_links
, cset_link
)
2388 count
+= atomic_read(&link
->cset
->refcount
);
2389 read_unlock(&css_set_lock
);
2394 * To reduce the fork() overhead for systems that are not actually using
2395 * their cgroups capability, we don't maintain the lists running through
2396 * each css_set to its tasks until we see the list actually used - in other
2397 * words after the first call to css_task_iter_start().
2399 static void cgroup_enable_task_cg_lists(void)
2401 struct task_struct
*p
, *g
;
2402 write_lock(&css_set_lock
);
2403 use_task_css_set_links
= 1;
2405 * We need tasklist_lock because RCU is not safe against
2406 * while_each_thread(). Besides, a forking task that has passed
2407 * cgroup_post_fork() without seeing use_task_css_set_links = 1
2408 * is not guaranteed to have its child immediately visible in the
2409 * tasklist if we walk through it with RCU.
2411 read_lock(&tasklist_lock
);
2412 do_each_thread(g
, p
) {
2415 * We should check if the process is exiting, otherwise
2416 * it will race with cgroup_exit() in that the list
2417 * entry won't be deleted though the process has exited.
2419 if (!(p
->flags
& PF_EXITING
) && list_empty(&p
->cg_list
))
2420 list_add(&p
->cg_list
, &task_css_set(p
)->tasks
);
2422 } while_each_thread(g
, p
);
2423 read_unlock(&tasklist_lock
);
2424 write_unlock(&css_set_lock
);
2428 * css_next_child - find the next child of a given css
2429 * @pos_css: the current position (%NULL to initiate traversal)
2430 * @parent_css: css whose children to walk
2432 * This function returns the next child of @parent_css and should be called
2433 * under either cgroup_mutex or RCU read lock. The only requirement is
2434 * that @parent_css and @pos_css are accessible. The next sibling is
2435 * guaranteed to be returned regardless of their states.
2437 struct cgroup_subsys_state
*
2438 css_next_child(struct cgroup_subsys_state
*pos_css
,
2439 struct cgroup_subsys_state
*parent_css
)
2441 struct cgroup
*pos
= pos_css
? pos_css
->cgroup
: NULL
;
2442 struct cgroup
*cgrp
= parent_css
->cgroup
;
2443 struct cgroup
*next
;
2445 cgroup_assert_mutexes_or_rcu_locked();
2448 * @pos could already have been removed. Once a cgroup is removed,
2449 * its ->sibling.next is no longer updated when its next sibling
2450 * changes. As CGRP_DEAD assertion is serialized and happens
2451 * before the cgroup is taken off the ->sibling list, if we see it
2452 * unasserted, it's guaranteed that the next sibling hasn't
2453 * finished its grace period even if it's already removed, and thus
2454 * safe to dereference from this RCU critical section. If
2455 * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed
2456 * to be visible as %true here.
2458 * If @pos is dead, its next pointer can't be dereferenced;
2459 * however, as each cgroup is given a monotonically increasing
2460 * unique serial number and always appended to the sibling list,
2461 * the next one can be found by walking the parent's children until
2462 * we see a cgroup with higher serial number than @pos's. While
2463 * this path can be slower, it's taken only when either the current
2464 * cgroup is removed or iteration and removal race.
2467 next
= list_entry_rcu(cgrp
->children
.next
, struct cgroup
, sibling
);
2468 } else if (likely(!cgroup_is_dead(pos
))) {
2469 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup
, sibling
);
2471 list_for_each_entry_rcu(next
, &cgrp
->children
, sibling
)
2472 if (next
->serial_nr
> pos
->serial_nr
)
2476 if (&next
->sibling
== &cgrp
->children
)
2479 return cgroup_css(next
, parent_css
->ss
);
2481 EXPORT_SYMBOL_GPL(css_next_child
);
2484 * css_next_descendant_pre - find the next descendant for pre-order walk
2485 * @pos: the current position (%NULL to initiate traversal)
2486 * @root: css whose descendants to walk
2488 * To be used by css_for_each_descendant_pre(). Find the next descendant
2489 * to visit for pre-order traversal of @root's descendants. @root is
2490 * included in the iteration and the first node to be visited.
2492 * While this function requires cgroup_mutex or RCU read locking, it
2493 * doesn't require the whole traversal to be contained in a single critical
2494 * section. This function will return the correct next descendant as long
2495 * as both @pos and @root are accessible and @pos is a descendant of @root.
2497 struct cgroup_subsys_state
*
2498 css_next_descendant_pre(struct cgroup_subsys_state
*pos
,
2499 struct cgroup_subsys_state
*root
)
2501 struct cgroup_subsys_state
*next
;
2503 cgroup_assert_mutexes_or_rcu_locked();
2505 /* if first iteration, visit @root */
2509 /* visit the first child if exists */
2510 next
= css_next_child(NULL
, pos
);
2514 /* no child, visit my or the closest ancestor's next sibling */
2515 while (pos
!= root
) {
2516 next
= css_next_child(pos
, css_parent(pos
));
2519 pos
= css_parent(pos
);
2524 EXPORT_SYMBOL_GPL(css_next_descendant_pre
);
2527 * css_rightmost_descendant - return the rightmost descendant of a css
2528 * @pos: css of interest
2530 * Return the rightmost descendant of @pos. If there's no descendant, @pos
2531 * is returned. This can be used during pre-order traversal to skip
2534 * While this function requires cgroup_mutex or RCU read locking, it
2535 * doesn't require the whole traversal to be contained in a single critical
2536 * section. This function will return the correct rightmost descendant as
2537 * long as @pos is accessible.
2539 struct cgroup_subsys_state
*
2540 css_rightmost_descendant(struct cgroup_subsys_state
*pos
)
2542 struct cgroup_subsys_state
*last
, *tmp
;
2544 cgroup_assert_mutexes_or_rcu_locked();
2548 /* ->prev isn't RCU safe, walk ->next till the end */
2550 css_for_each_child(tmp
, last
)
2556 EXPORT_SYMBOL_GPL(css_rightmost_descendant
);
2558 static struct cgroup_subsys_state
*
2559 css_leftmost_descendant(struct cgroup_subsys_state
*pos
)
2561 struct cgroup_subsys_state
*last
;
2565 pos
= css_next_child(NULL
, pos
);
2572 * css_next_descendant_post - find the next descendant for post-order walk
2573 * @pos: the current position (%NULL to initiate traversal)
2574 * @root: css whose descendants to walk
2576 * To be used by css_for_each_descendant_post(). Find the next descendant
2577 * to visit for post-order traversal of @root's descendants. @root is
2578 * included in the iteration and the last node to be visited.
2580 * While this function requires cgroup_mutex or RCU read locking, it
2581 * doesn't require the whole traversal to be contained in a single critical
2582 * section. This function will return the correct next descendant as long
2583 * as both @pos and @cgroup are accessible and @pos is a descendant of
2586 struct cgroup_subsys_state
*
2587 css_next_descendant_post(struct cgroup_subsys_state
*pos
,
2588 struct cgroup_subsys_state
*root
)
2590 struct cgroup_subsys_state
*next
;
2592 cgroup_assert_mutexes_or_rcu_locked();
2594 /* if first iteration, visit leftmost descendant which may be @root */
2596 return css_leftmost_descendant(root
);
2598 /* if we visited @root, we're done */
2602 /* if there's an unvisited sibling, visit its leftmost descendant */
2603 next
= css_next_child(pos
, css_parent(pos
));
2605 return css_leftmost_descendant(next
);
2607 /* no sibling left, visit parent */
2608 return css_parent(pos
);
2610 EXPORT_SYMBOL_GPL(css_next_descendant_post
);
2613 * css_advance_task_iter - advance a task itererator to the next css_set
2614 * @it: the iterator to advance
2616 * Advance @it to the next css_set to walk.
2618 static void css_advance_task_iter(struct css_task_iter
*it
)
2620 struct list_head
*l
= it
->cset_link
;
2621 struct cgrp_cset_link
*link
;
2622 struct css_set
*cset
;
2624 /* Advance to the next non-empty css_set */
2627 if (l
== &it
->origin_css
->cgroup
->cset_links
) {
2628 it
->cset_link
= NULL
;
2631 link
= list_entry(l
, struct cgrp_cset_link
, cset_link
);
2633 } while (list_empty(&cset
->tasks
));
2635 it
->task
= cset
->tasks
.next
;
2639 * css_task_iter_start - initiate task iteration
2640 * @css: the css to walk tasks of
2641 * @it: the task iterator to use
2643 * Initiate iteration through the tasks of @css. The caller can call
2644 * css_task_iter_next() to walk through the tasks until the function
2645 * returns NULL. On completion of iteration, css_task_iter_end() must be
2648 * Note that this function acquires a lock which is released when the
2649 * iteration finishes. The caller can't sleep while iteration is in
2652 void css_task_iter_start(struct cgroup_subsys_state
*css
,
2653 struct css_task_iter
*it
)
2654 __acquires(css_set_lock
)
2657 * The first time anyone tries to iterate across a css, we need to
2658 * enable the list linking each css_set to its tasks, and fix up
2659 * all existing tasks.
2661 if (!use_task_css_set_links
)
2662 cgroup_enable_task_cg_lists();
2664 read_lock(&css_set_lock
);
2666 it
->origin_css
= css
;
2667 it
->cset_link
= &css
->cgroup
->cset_links
;
2669 css_advance_task_iter(it
);
2673 * css_task_iter_next - return the next task for the iterator
2674 * @it: the task iterator being iterated
2676 * The "next" function for task iteration. @it should have been
2677 * initialized via css_task_iter_start(). Returns NULL when the iteration
2680 struct task_struct
*css_task_iter_next(struct css_task_iter
*it
)
2682 struct task_struct
*res
;
2683 struct list_head
*l
= it
->task
;
2684 struct cgrp_cset_link
*link
;
2686 /* If the iterator cg is NULL, we have no tasks */
2689 res
= list_entry(l
, struct task_struct
, cg_list
);
2690 /* Advance iterator to find next entry */
2692 link
= list_entry(it
->cset_link
, struct cgrp_cset_link
, cset_link
);
2693 if (l
== &link
->cset
->tasks
) {
2695 * We reached the end of this task list - move on to the
2696 * next cgrp_cset_link.
2698 css_advance_task_iter(it
);
2706 * css_task_iter_end - finish task iteration
2707 * @it: the task iterator to finish
2709 * Finish task iteration started by css_task_iter_start().
2711 void css_task_iter_end(struct css_task_iter
*it
)
2712 __releases(css_set_lock
)
2714 read_unlock(&css_set_lock
);
2717 static inline int started_after_time(struct task_struct
*t1
,
2718 struct timespec
*time
,
2719 struct task_struct
*t2
)
2721 int start_diff
= timespec_compare(&t1
->start_time
, time
);
2722 if (start_diff
> 0) {
2724 } else if (start_diff
< 0) {
2728 * Arbitrarily, if two processes started at the same
2729 * time, we'll say that the lower pointer value
2730 * started first. Note that t2 may have exited by now
2731 * so this may not be a valid pointer any longer, but
2732 * that's fine - it still serves to distinguish
2733 * between two tasks started (effectively) simultaneously.
2740 * This function is a callback from heap_insert() and is used to order
2742 * In this case we order the heap in descending task start time.
2744 static inline int started_after(void *p1
, void *p2
)
2746 struct task_struct
*t1
= p1
;
2747 struct task_struct
*t2
= p2
;
2748 return started_after_time(t1
, &t2
->start_time
, t2
);
2752 * css_scan_tasks - iterate though all the tasks in a css
2753 * @css: the css to iterate tasks of
2754 * @test: optional test callback
2755 * @process: process callback
2756 * @data: data passed to @test and @process
2757 * @heap: optional pre-allocated heap used for task iteration
2759 * Iterate through all the tasks in @css, calling @test for each, and if it
2760 * returns %true, call @process for it also.
2762 * @test may be NULL, meaning always true (select all tasks), which
2763 * effectively duplicates css_task_iter_{start,next,end}() but does not
2764 * lock css_set_lock for the call to @process.
2766 * It is guaranteed that @process will act on every task that is a member
2767 * of @css for the duration of this call. This function may or may not
2768 * call @process for tasks that exit or move to a different css during the
2769 * call, or are forked or move into the css during the call.
2771 * Note that @test may be called with locks held, and may in some
2772 * situations be called multiple times for the same task, so it should be
2775 * If @heap is non-NULL, a heap has been pre-allocated and will be used for
2776 * heap operations (and its "gt" member will be overwritten), else a
2777 * temporary heap will be used (allocation of which may cause this function
2780 int css_scan_tasks(struct cgroup_subsys_state
*css
,
2781 bool (*test
)(struct task_struct
*, void *),
2782 void (*process
)(struct task_struct
*, void *),
2783 void *data
, struct ptr_heap
*heap
)
2786 struct css_task_iter it
;
2787 struct task_struct
*p
, *dropped
;
2788 /* Never dereference latest_task, since it's not refcounted */
2789 struct task_struct
*latest_task
= NULL
;
2790 struct ptr_heap tmp_heap
;
2791 struct timespec latest_time
= { 0, 0 };
2794 /* The caller supplied our heap and pre-allocated its memory */
2795 heap
->gt
= &started_after
;
2797 /* We need to allocate our own heap memory */
2799 retval
= heap_init(heap
, PAGE_SIZE
, GFP_KERNEL
, &started_after
);
2801 /* cannot allocate the heap */
2807 * Scan tasks in the css, using the @test callback to determine
2808 * which are of interest, and invoking @process callback on the
2809 * ones which need an update. Since we don't want to hold any
2810 * locks during the task updates, gather tasks to be processed in a
2811 * heap structure. The heap is sorted by descending task start
2812 * time. If the statically-sized heap fills up, we overflow tasks
2813 * that started later, and in future iterations only consider tasks
2814 * that started after the latest task in the previous pass. This
2815 * guarantees forward progress and that we don't miss any tasks.
2818 css_task_iter_start(css
, &it
);
2819 while ((p
= css_task_iter_next(&it
))) {
2821 * Only affect tasks that qualify per the caller's callback,
2822 * if he provided one
2824 if (test
&& !test(p
, data
))
2827 * Only process tasks that started after the last task
2830 if (!started_after_time(p
, &latest_time
, latest_task
))
2832 dropped
= heap_insert(heap
, p
);
2833 if (dropped
== NULL
) {
2835 * The new task was inserted; the heap wasn't
2839 } else if (dropped
!= p
) {
2841 * The new task was inserted, and pushed out a
2845 put_task_struct(dropped
);
2848 * Else the new task was newer than anything already in
2849 * the heap and wasn't inserted
2852 css_task_iter_end(&it
);
2855 for (i
= 0; i
< heap
->size
; i
++) {
2856 struct task_struct
*q
= heap
->ptrs
[i
];
2858 latest_time
= q
->start_time
;
2861 /* Process the task per the caller's callback */
2866 * If we had to process any tasks at all, scan again
2867 * in case some of them were in the middle of forking
2868 * children that didn't get processed.
2869 * Not the most efficient way to do it, but it avoids
2870 * having to take callback_mutex in the fork path
2874 if (heap
== &tmp_heap
)
2875 heap_free(&tmp_heap
);
2879 static void cgroup_transfer_one_task(struct task_struct
*task
, void *data
)
2881 struct cgroup
*new_cgroup
= data
;
2883 mutex_lock(&cgroup_mutex
);
2884 cgroup_attach_task(new_cgroup
, task
, false);
2885 mutex_unlock(&cgroup_mutex
);
2889 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
2890 * @to: cgroup to which the tasks will be moved
2891 * @from: cgroup in which the tasks currently reside
2893 int cgroup_transfer_tasks(struct cgroup
*to
, struct cgroup
*from
)
2895 return css_scan_tasks(&from
->dummy_css
, NULL
, cgroup_transfer_one_task
,
2900 * Stuff for reading the 'tasks'/'procs' files.
2902 * Reading this file can return large amounts of data if a cgroup has
2903 * *lots* of attached tasks. So it may need several calls to read(),
2904 * but we cannot guarantee that the information we produce is correct
2905 * unless we produce it entirely atomically.
2909 /* which pidlist file are we talking about? */
2910 enum cgroup_filetype
{
2916 * A pidlist is a list of pids that virtually represents the contents of one
2917 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
2918 * a pair (one each for procs, tasks) for each pid namespace that's relevant
2921 struct cgroup_pidlist
{
2923 * used to find which pidlist is wanted. doesn't change as long as
2924 * this particular list stays in the list.
2926 struct { enum cgroup_filetype type
; struct pid_namespace
*ns
; } key
;
2929 /* how many elements the above list has */
2931 /* each of these stored in a list by its cgroup */
2932 struct list_head links
;
2933 /* pointer to the cgroup we belong to, for list removal purposes */
2934 struct cgroup
*owner
;
2935 /* for delayed destruction */
2936 struct delayed_work destroy_dwork
;
2940 * The following two functions "fix" the issue where there are more pids
2941 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
2942 * TODO: replace with a kernel-wide solution to this problem
2944 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
2945 static void *pidlist_allocate(int count
)
2947 if (PIDLIST_TOO_LARGE(count
))
2948 return vmalloc(count
* sizeof(pid_t
));
2950 return kmalloc(count
* sizeof(pid_t
), GFP_KERNEL
);
2953 static void pidlist_free(void *p
)
2955 if (is_vmalloc_addr(p
))
2962 * Used to destroy all pidlists lingering waiting for destroy timer. None
2963 * should be left afterwards.
2965 static void cgroup_pidlist_destroy_all(struct cgroup
*cgrp
)
2967 struct cgroup_pidlist
*l
, *tmp_l
;
2969 mutex_lock(&cgrp
->pidlist_mutex
);
2970 list_for_each_entry_safe(l
, tmp_l
, &cgrp
->pidlists
, links
)
2971 mod_delayed_work(cgroup_pidlist_destroy_wq
, &l
->destroy_dwork
, 0);
2972 mutex_unlock(&cgrp
->pidlist_mutex
);
2974 flush_workqueue(cgroup_pidlist_destroy_wq
);
2975 BUG_ON(!list_empty(&cgrp
->pidlists
));
2978 static void cgroup_pidlist_destroy_work_fn(struct work_struct
*work
)
2980 struct delayed_work
*dwork
= to_delayed_work(work
);
2981 struct cgroup_pidlist
*l
= container_of(dwork
, struct cgroup_pidlist
,
2983 struct cgroup_pidlist
*tofree
= NULL
;
2985 mutex_lock(&l
->owner
->pidlist_mutex
);
2988 * Destroy iff we didn't get queued again. The state won't change
2989 * as destroy_dwork can only be queued while locked.
2991 if (!delayed_work_pending(dwork
)) {
2992 list_del(&l
->links
);
2993 pidlist_free(l
->list
);
2994 put_pid_ns(l
->key
.ns
);
2998 mutex_unlock(&l
->owner
->pidlist_mutex
);
3003 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
3004 * Returns the number of unique elements.
3006 static int pidlist_uniq(pid_t
*list
, int length
)
3011 * we presume the 0th element is unique, so i starts at 1. trivial
3012 * edge cases first; no work needs to be done for either
3014 if (length
== 0 || length
== 1)
3016 /* src and dest walk down the list; dest counts unique elements */
3017 for (src
= 1; src
< length
; src
++) {
3018 /* find next unique element */
3019 while (list
[src
] == list
[src
-1]) {
3024 /* dest always points to where the next unique element goes */
3025 list
[dest
] = list
[src
];
3033 * The two pid files - task and cgroup.procs - guaranteed that the result
3034 * is sorted, which forced this whole pidlist fiasco. As pid order is
3035 * different per namespace, each namespace needs differently sorted list,
3036 * making it impossible to use, for example, single rbtree of member tasks
3037 * sorted by task pointer. As pidlists can be fairly large, allocating one
3038 * per open file is dangerous, so cgroup had to implement shared pool of
3039 * pidlists keyed by cgroup and namespace.
3041 * All this extra complexity was caused by the original implementation
3042 * committing to an entirely unnecessary property. In the long term, we
3043 * want to do away with it. Explicitly scramble sort order if
3044 * sane_behavior so that no such expectation exists in the new interface.
3046 * Scrambling is done by swapping every two consecutive bits, which is
3047 * non-identity one-to-one mapping which disturbs sort order sufficiently.
3049 static pid_t
pid_fry(pid_t pid
)
3051 unsigned a
= pid
& 0x55555555;
3052 unsigned b
= pid
& 0xAAAAAAAA;
3054 return (a
<< 1) | (b
>> 1);
3057 static pid_t
cgroup_pid_fry(struct cgroup
*cgrp
, pid_t pid
)
3059 if (cgroup_sane_behavior(cgrp
))
3060 return pid_fry(pid
);
3065 static int cmppid(const void *a
, const void *b
)
3067 return *(pid_t
*)a
- *(pid_t
*)b
;
3070 static int fried_cmppid(const void *a
, const void *b
)
3072 return pid_fry(*(pid_t
*)a
) - pid_fry(*(pid_t
*)b
);
3075 static struct cgroup_pidlist
*cgroup_pidlist_find(struct cgroup
*cgrp
,
3076 enum cgroup_filetype type
)
3078 struct cgroup_pidlist
*l
;
3079 /* don't need task_nsproxy() if we're looking at ourself */
3080 struct pid_namespace
*ns
= task_active_pid_ns(current
);
3082 lockdep_assert_held(&cgrp
->pidlist_mutex
);
3084 list_for_each_entry(l
, &cgrp
->pidlists
, links
)
3085 if (l
->key
.type
== type
&& l
->key
.ns
== ns
)
3091 * find the appropriate pidlist for our purpose (given procs vs tasks)
3092 * returns with the lock on that pidlist already held, and takes care
3093 * of the use count, or returns NULL with no locks held if we're out of
3096 static struct cgroup_pidlist
*cgroup_pidlist_find_create(struct cgroup
*cgrp
,
3097 enum cgroup_filetype type
)
3099 struct cgroup_pidlist
*l
;
3101 lockdep_assert_held(&cgrp
->pidlist_mutex
);
3103 l
= cgroup_pidlist_find(cgrp
, type
);
3107 /* entry not found; create a new one */
3108 l
= kzalloc(sizeof(struct cgroup_pidlist
), GFP_KERNEL
);
3112 INIT_DELAYED_WORK(&l
->destroy_dwork
, cgroup_pidlist_destroy_work_fn
);
3114 /* don't need task_nsproxy() if we're looking at ourself */
3115 l
->key
.ns
= get_pid_ns(task_active_pid_ns(current
));
3117 list_add(&l
->links
, &cgrp
->pidlists
);
3122 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
3124 static int pidlist_array_load(struct cgroup
*cgrp
, enum cgroup_filetype type
,
3125 struct cgroup_pidlist
**lp
)
3129 int pid
, n
= 0; /* used for populating the array */
3130 struct css_task_iter it
;
3131 struct task_struct
*tsk
;
3132 struct cgroup_pidlist
*l
;
3134 lockdep_assert_held(&cgrp
->pidlist_mutex
);
3137 * If cgroup gets more users after we read count, we won't have
3138 * enough space - tough. This race is indistinguishable to the
3139 * caller from the case that the additional cgroup users didn't
3140 * show up until sometime later on.
3142 length
= cgroup_task_count(cgrp
);
3143 array
= pidlist_allocate(length
);
3146 /* now, populate the array */
3147 css_task_iter_start(&cgrp
->dummy_css
, &it
);
3148 while ((tsk
= css_task_iter_next(&it
))) {
3149 if (unlikely(n
== length
))
3151 /* get tgid or pid for procs or tasks file respectively */
3152 if (type
== CGROUP_FILE_PROCS
)
3153 pid
= task_tgid_vnr(tsk
);
3155 pid
= task_pid_vnr(tsk
);
3156 if (pid
> 0) /* make sure to only use valid results */
3159 css_task_iter_end(&it
);
3161 /* now sort & (if procs) strip out duplicates */
3162 if (cgroup_sane_behavior(cgrp
))
3163 sort(array
, length
, sizeof(pid_t
), fried_cmppid
, NULL
);
3165 sort(array
, length
, sizeof(pid_t
), cmppid
, NULL
);
3166 if (type
== CGROUP_FILE_PROCS
)
3167 length
= pidlist_uniq(array
, length
);
3169 l
= cgroup_pidlist_find_create(cgrp
, type
);
3171 mutex_unlock(&cgrp
->pidlist_mutex
);
3172 pidlist_free(array
);
3176 /* store array, freeing old if necessary */
3177 pidlist_free(l
->list
);
3185 * cgroupstats_build - build and fill cgroupstats
3186 * @stats: cgroupstats to fill information into
3187 * @dentry: A dentry entry belonging to the cgroup for which stats have
3190 * Build and fill cgroupstats so that taskstats can export it to user
3193 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
3195 struct kernfs_node
*kn
= kernfs_node_from_dentry(dentry
);
3196 struct cgroup
*cgrp
;
3197 struct css_task_iter it
;
3198 struct task_struct
*tsk
;
3200 /* it should be kernfs_node belonging to cgroupfs and is a directory */
3201 if (dentry
->d_sb
->s_type
!= &cgroup_fs_type
|| !kn
||
3202 kernfs_type(kn
) != KERNFS_DIR
)
3206 * We aren't being called from kernfs and there's no guarantee on
3207 * @kn->priv's validity. For this and css_tryget_from_dir(),
3208 * @kn->priv is RCU safe. Let's do the RCU dancing.
3211 cgrp
= rcu_dereference(kn
->priv
);
3217 css_task_iter_start(&cgrp
->dummy_css
, &it
);
3218 while ((tsk
= css_task_iter_next(&it
))) {
3219 switch (tsk
->state
) {
3221 stats
->nr_running
++;
3223 case TASK_INTERRUPTIBLE
:
3224 stats
->nr_sleeping
++;
3226 case TASK_UNINTERRUPTIBLE
:
3227 stats
->nr_uninterruptible
++;
3230 stats
->nr_stopped
++;
3233 if (delayacct_is_task_waiting_on_io(tsk
))
3234 stats
->nr_io_wait
++;
3238 css_task_iter_end(&it
);
3246 * seq_file methods for the tasks/procs files. The seq_file position is the
3247 * next pid to display; the seq_file iterator is a pointer to the pid
3248 * in the cgroup->l->list array.
3251 static void *cgroup_pidlist_start(struct seq_file
*s
, loff_t
*pos
)
3254 * Initially we receive a position value that corresponds to
3255 * one more than the last pid shown (or 0 on the first call or
3256 * after a seek to the start). Use a binary-search to find the
3257 * next pid to display, if any
3259 struct kernfs_open_file
*of
= s
->private;
3260 struct cgroup
*cgrp
= seq_css(s
)->cgroup
;
3261 struct cgroup_pidlist
*l
;
3262 enum cgroup_filetype type
= seq_cft(s
)->private;
3263 int index
= 0, pid
= *pos
;
3266 mutex_lock(&cgrp
->pidlist_mutex
);
3269 * !NULL @of->priv indicates that this isn't the first start()
3270 * after open. If the matching pidlist is around, we can use that.
3271 * Look for it. Note that @of->priv can't be used directly. It
3272 * could already have been destroyed.
3275 of
->priv
= cgroup_pidlist_find(cgrp
, type
);
3278 * Either this is the first start() after open or the matching
3279 * pidlist has been destroyed inbetween. Create a new one.
3282 ret
= pidlist_array_load(cgrp
, type
,
3283 (struct cgroup_pidlist
**)&of
->priv
);
3285 return ERR_PTR(ret
);
3290 int end
= l
->length
;
3292 while (index
< end
) {
3293 int mid
= (index
+ end
) / 2;
3294 if (cgroup_pid_fry(cgrp
, l
->list
[mid
]) == pid
) {
3297 } else if (cgroup_pid_fry(cgrp
, l
->list
[mid
]) <= pid
)
3303 /* If we're off the end of the array, we're done */
3304 if (index
>= l
->length
)
3306 /* Update the abstract position to be the actual pid that we found */
3307 iter
= l
->list
+ index
;
3308 *pos
= cgroup_pid_fry(cgrp
, *iter
);
3312 static void cgroup_pidlist_stop(struct seq_file
*s
, void *v
)
3314 struct kernfs_open_file
*of
= s
->private;
3315 struct cgroup_pidlist
*l
= of
->priv
;
3318 mod_delayed_work(cgroup_pidlist_destroy_wq
, &l
->destroy_dwork
,
3319 CGROUP_PIDLIST_DESTROY_DELAY
);
3320 mutex_unlock(&seq_css(s
)->cgroup
->pidlist_mutex
);
3323 static void *cgroup_pidlist_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
3325 struct kernfs_open_file
*of
= s
->private;
3326 struct cgroup_pidlist
*l
= of
->priv
;
3328 pid_t
*end
= l
->list
+ l
->length
;
3330 * Advance to the next pid in the array. If this goes off the
3337 *pos
= cgroup_pid_fry(seq_css(s
)->cgroup
, *p
);
3342 static int cgroup_pidlist_show(struct seq_file
*s
, void *v
)
3344 return seq_printf(s
, "%d\n", *(int *)v
);
3348 * seq_operations functions for iterating on pidlists through seq_file -
3349 * independent of whether it's tasks or procs
3351 static const struct seq_operations cgroup_pidlist_seq_operations
= {
3352 .start
= cgroup_pidlist_start
,
3353 .stop
= cgroup_pidlist_stop
,
3354 .next
= cgroup_pidlist_next
,
3355 .show
= cgroup_pidlist_show
,
3358 static u64
cgroup_read_notify_on_release(struct cgroup_subsys_state
*css
,
3361 return notify_on_release(css
->cgroup
);
3364 static int cgroup_write_notify_on_release(struct cgroup_subsys_state
*css
,
3365 struct cftype
*cft
, u64 val
)
3367 clear_bit(CGRP_RELEASABLE
, &css
->cgroup
->flags
);
3369 set_bit(CGRP_NOTIFY_ON_RELEASE
, &css
->cgroup
->flags
);
3371 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &css
->cgroup
->flags
);
3375 static u64
cgroup_clone_children_read(struct cgroup_subsys_state
*css
,
3378 return test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
3381 static int cgroup_clone_children_write(struct cgroup_subsys_state
*css
,
3382 struct cftype
*cft
, u64 val
)
3385 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
3387 clear_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
3391 static struct cftype cgroup_base_files
[] = {
3393 .name
= "cgroup.procs",
3394 .seq_start
= cgroup_pidlist_start
,
3395 .seq_next
= cgroup_pidlist_next
,
3396 .seq_stop
= cgroup_pidlist_stop
,
3397 .seq_show
= cgroup_pidlist_show
,
3398 .private = CGROUP_FILE_PROCS
,
3399 .write_u64
= cgroup_procs_write
,
3400 .mode
= S_IRUGO
| S_IWUSR
,
3403 .name
= "cgroup.clone_children",
3404 .flags
= CFTYPE_INSANE
,
3405 .read_u64
= cgroup_clone_children_read
,
3406 .write_u64
= cgroup_clone_children_write
,
3409 .name
= "cgroup.sane_behavior",
3410 .flags
= CFTYPE_ONLY_ON_ROOT
,
3411 .seq_show
= cgroup_sane_behavior_show
,
3415 * Historical crazy stuff. These don't have "cgroup." prefix and
3416 * don't exist if sane_behavior. If you're depending on these, be
3417 * prepared to be burned.
3421 .flags
= CFTYPE_INSANE
, /* use "procs" instead */
3422 .seq_start
= cgroup_pidlist_start
,
3423 .seq_next
= cgroup_pidlist_next
,
3424 .seq_stop
= cgroup_pidlist_stop
,
3425 .seq_show
= cgroup_pidlist_show
,
3426 .private = CGROUP_FILE_TASKS
,
3427 .write_u64
= cgroup_tasks_write
,
3428 .mode
= S_IRUGO
| S_IWUSR
,
3431 .name
= "notify_on_release",
3432 .flags
= CFTYPE_INSANE
,
3433 .read_u64
= cgroup_read_notify_on_release
,
3434 .write_u64
= cgroup_write_notify_on_release
,
3437 .name
= "release_agent",
3438 .flags
= CFTYPE_INSANE
| CFTYPE_ONLY_ON_ROOT
,
3439 .seq_show
= cgroup_release_agent_show
,
3440 .write_string
= cgroup_release_agent_write
,
3441 .max_write_len
= PATH_MAX
- 1,
3447 * cgroup_populate_dir - create subsys files in a cgroup directory
3448 * @cgrp: target cgroup
3449 * @subsys_mask: mask of the subsystem ids whose files should be added
3451 * On failure, no file is added.
3453 static int cgroup_populate_dir(struct cgroup
*cgrp
, unsigned long subsys_mask
)
3455 struct cgroup_subsys
*ss
;
3458 /* process cftsets of each subsystem */
3459 for_each_subsys(ss
, i
) {
3460 struct cftype
*cfts
;
3462 if (!test_bit(i
, &subsys_mask
))
3465 list_for_each_entry(cfts
, &ss
->cfts
, node
) {
3466 ret
= cgroup_addrm_files(cgrp
, cfts
, true);
3473 cgroup_clear_dir(cgrp
, subsys_mask
);
3478 * css destruction is four-stage process.
3480 * 1. Destruction starts. Killing of the percpu_ref is initiated.
3481 * Implemented in kill_css().
3483 * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
3484 * and thus css_tryget() is guaranteed to fail, the css can be offlined
3485 * by invoking offline_css(). After offlining, the base ref is put.
3486 * Implemented in css_killed_work_fn().
3488 * 3. When the percpu_ref reaches zero, the only possible remaining
3489 * accessors are inside RCU read sections. css_release() schedules the
3492 * 4. After the grace period, the css can be freed. Implemented in
3493 * css_free_work_fn().
3495 * It is actually hairier because both step 2 and 4 require process context
3496 * and thus involve punting to css->destroy_work adding two additional
3497 * steps to the already complex sequence.
3499 static void css_free_work_fn(struct work_struct
*work
)
3501 struct cgroup_subsys_state
*css
=
3502 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
3503 struct cgroup
*cgrp
= css
->cgroup
;
3506 css_put(css
->parent
);
3508 css
->ss
->css_free(css
);
3512 static void css_free_rcu_fn(struct rcu_head
*rcu_head
)
3514 struct cgroup_subsys_state
*css
=
3515 container_of(rcu_head
, struct cgroup_subsys_state
, rcu_head
);
3517 INIT_WORK(&css
->destroy_work
, css_free_work_fn
);
3518 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
3521 static void css_release(struct percpu_ref
*ref
)
3523 struct cgroup_subsys_state
*css
=
3524 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
3526 rcu_assign_pointer(css
->cgroup
->subsys
[css
->ss
->id
], NULL
);
3527 call_rcu(&css
->rcu_head
, css_free_rcu_fn
);
3530 static void init_css(struct cgroup_subsys_state
*css
, struct cgroup_subsys
*ss
,
3531 struct cgroup
*cgrp
)
3538 css
->parent
= cgroup_css(cgrp
->parent
, ss
);
3540 css
->flags
|= CSS_ROOT
;
3542 BUG_ON(cgroup_css(cgrp
, ss
));
3545 /* invoke ->css_online() on a new CSS and mark it online if successful */
3546 static int online_css(struct cgroup_subsys_state
*css
)
3548 struct cgroup_subsys
*ss
= css
->ss
;
3551 lockdep_assert_held(&cgroup_tree_mutex
);
3552 lockdep_assert_held(&cgroup_mutex
);
3555 ret
= ss
->css_online(css
);
3557 css
->flags
|= CSS_ONLINE
;
3558 css
->cgroup
->nr_css
++;
3559 rcu_assign_pointer(css
->cgroup
->subsys
[ss
->id
], css
);
3564 /* if the CSS is online, invoke ->css_offline() on it and mark it offline */
3565 static void offline_css(struct cgroup_subsys_state
*css
)
3567 struct cgroup_subsys
*ss
= css
->ss
;
3569 lockdep_assert_held(&cgroup_tree_mutex
);
3570 lockdep_assert_held(&cgroup_mutex
);
3572 if (!(css
->flags
& CSS_ONLINE
))
3575 if (ss
->css_offline
)
3576 ss
->css_offline(css
);
3578 css
->flags
&= ~CSS_ONLINE
;
3579 css
->cgroup
->nr_css
--;
3580 RCU_INIT_POINTER(css
->cgroup
->subsys
[ss
->id
], css
);
3584 * create_css - create a cgroup_subsys_state
3585 * @cgrp: the cgroup new css will be associated with
3586 * @ss: the subsys of new css
3588 * Create a new css associated with @cgrp - @ss pair. On success, the new
3589 * css is online and installed in @cgrp with all interface files created.
3590 * Returns 0 on success, -errno on failure.
3592 static int create_css(struct cgroup
*cgrp
, struct cgroup_subsys
*ss
)
3594 struct cgroup
*parent
= cgrp
->parent
;
3595 struct cgroup_subsys_state
*css
;
3598 lockdep_assert_held(&cgroup_mutex
);
3600 css
= ss
->css_alloc(cgroup_css(parent
, ss
));
3602 return PTR_ERR(css
);
3604 err
= percpu_ref_init(&css
->refcnt
, css_release
);
3608 init_css(css
, ss
, cgrp
);
3610 err
= cgroup_populate_dir(cgrp
, 1 << ss
->id
);
3614 err
= online_css(css
);
3619 css_get(css
->parent
);
3621 if (ss
->broken_hierarchy
&& !ss
->warned_broken_hierarchy
&&
3623 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",
3624 current
->comm
, current
->pid
, ss
->name
);
3625 if (!strcmp(ss
->name
, "memory"))
3626 pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
3627 ss
->warned_broken_hierarchy
= true;
3633 percpu_ref_cancel_init(&css
->refcnt
);
3639 * cgroup_create - create a cgroup
3640 * @parent: cgroup that will be parent of the new cgroup
3641 * @name: name of the new cgroup
3642 * @mode: mode to set on new cgroup
3644 static long cgroup_create(struct cgroup
*parent
, const char *name
,
3647 struct cgroup
*cgrp
;
3648 struct cgroupfs_root
*root
= parent
->root
;
3650 struct cgroup_subsys
*ss
;
3651 struct kernfs_node
*kn
;
3653 /* allocate the cgroup and its ID, 0 is reserved for the root */
3654 cgrp
= kzalloc(sizeof(*cgrp
), GFP_KERNEL
);
3658 mutex_lock(&cgroup_tree_mutex
);
3661 * Only live parents can have children. Note that the liveliness
3662 * check isn't strictly necessary because cgroup_mkdir() and
3663 * cgroup_rmdir() are fully synchronized by i_mutex; however, do it
3664 * anyway so that locking is contained inside cgroup proper and we
3665 * don't get nasty surprises if we ever grow another caller.
3667 if (!cgroup_lock_live_group(parent
)) {
3669 goto err_unlock_tree
;
3673 * Temporarily set the pointer to NULL, so idr_find() won't return
3674 * a half-baked cgroup.
3676 cgrp
->id
= idr_alloc(&root
->cgroup_idr
, NULL
, 1, 0, GFP_KERNEL
);
3682 init_cgroup_housekeeping(cgrp
);
3684 cgrp
->parent
= parent
;
3685 cgrp
->dummy_css
.parent
= &parent
->dummy_css
;
3686 cgrp
->root
= parent
->root
;
3688 if (notify_on_release(parent
))
3689 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
3691 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
))
3692 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
3694 /* create the directory */
3695 kn
= kernfs_create_dir(parent
->kn
, name
, mode
, cgrp
);
3703 * This extra ref will be put in cgroup_free_fn() and guarantees
3704 * that @cgrp->kn is always accessible.
3708 cgrp
->serial_nr
= cgroup_serial_nr_next
++;
3710 /* allocation complete, commit to creation */
3711 list_add_tail_rcu(&cgrp
->sibling
, &cgrp
->parent
->children
);
3712 root
->number_of_cgroups
++;
3715 * Grab a reference on the root and parent so that they don't get
3716 * deleted while there are child cgroups.
3718 cgroup_get_root(root
);
3722 * @cgrp is now fully operational. If something fails after this
3723 * point, it'll be released via the normal destruction path.
3725 idr_replace(&root
->cgroup_idr
, cgrp
, cgrp
->id
);
3727 err
= cgroup_addrm_files(cgrp
, cgroup_base_files
, true);
3731 /* let's create and online css's */
3732 for_each_subsys(ss
, ssid
) {
3733 if (root
->subsys_mask
& (1 << ssid
)) {
3734 err
= create_css(cgrp
, ss
);
3740 kernfs_activate(kn
);
3742 mutex_unlock(&cgroup_mutex
);
3743 mutex_unlock(&cgroup_tree_mutex
);
3748 idr_remove(&root
->cgroup_idr
, cgrp
->id
);
3750 mutex_unlock(&cgroup_mutex
);
3752 mutex_unlock(&cgroup_tree_mutex
);
3757 cgroup_destroy_locked(cgrp
);
3758 mutex_unlock(&cgroup_mutex
);
3759 mutex_unlock(&cgroup_tree_mutex
);
3763 static int cgroup_mkdir(struct kernfs_node
*parent_kn
, const char *name
,
3766 struct cgroup
*parent
= parent_kn
->priv
;
3768 return cgroup_create(parent
, name
, mode
);
3772 * This is called when the refcnt of a css is confirmed to be killed.
3773 * css_tryget() is now guaranteed to fail.
3775 static void css_killed_work_fn(struct work_struct
*work
)
3777 struct cgroup_subsys_state
*css
=
3778 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
3779 struct cgroup
*cgrp
= css
->cgroup
;
3781 mutex_lock(&cgroup_tree_mutex
);
3782 mutex_lock(&cgroup_mutex
);
3785 * css_tryget() is guaranteed to fail now. Tell subsystems to
3786 * initate destruction.
3791 * If @cgrp is marked dead, it's waiting for refs of all css's to
3792 * be disabled before proceeding to the second phase of cgroup
3793 * destruction. If we are the last one, kick it off.
3795 if (!cgrp
->nr_css
&& cgroup_is_dead(cgrp
))
3796 cgroup_destroy_css_killed(cgrp
);
3798 mutex_unlock(&cgroup_mutex
);
3799 mutex_unlock(&cgroup_tree_mutex
);
3802 * Put the css refs from kill_css(). Each css holds an extra
3803 * reference to the cgroup's dentry and cgroup removal proceeds
3804 * regardless of css refs. On the last put of each css, whenever
3805 * that may be, the extra dentry ref is put so that dentry
3806 * destruction happens only after all css's are released.
3811 /* css kill confirmation processing requires process context, bounce */
3812 static void css_killed_ref_fn(struct percpu_ref
*ref
)
3814 struct cgroup_subsys_state
*css
=
3815 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
3817 INIT_WORK(&css
->destroy_work
, css_killed_work_fn
);
3818 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
3822 * kill_css - destroy a css
3823 * @css: css to destroy
3825 * This function initiates destruction of @css by removing cgroup interface
3826 * files and putting its base reference. ->css_offline() will be invoked
3827 * asynchronously once css_tryget() is guaranteed to fail and when the
3828 * reference count reaches zero, @css will be released.
3830 static void kill_css(struct cgroup_subsys_state
*css
)
3833 * This must happen before css is disassociated with its cgroup.
3834 * See seq_css() for details.
3836 cgroup_clear_dir(css
->cgroup
, 1 << css
->ss
->id
);
3839 * Killing would put the base ref, but we need to keep it alive
3840 * until after ->css_offline().
3845 * cgroup core guarantees that, by the time ->css_offline() is
3846 * invoked, no new css reference will be given out via
3847 * css_tryget(). We can't simply call percpu_ref_kill() and
3848 * proceed to offlining css's because percpu_ref_kill() doesn't
3849 * guarantee that the ref is seen as killed on all CPUs on return.
3851 * Use percpu_ref_kill_and_confirm() to get notifications as each
3852 * css is confirmed to be seen as killed on all CPUs.
3854 percpu_ref_kill_and_confirm(&css
->refcnt
, css_killed_ref_fn
);
3858 * cgroup_destroy_locked - the first stage of cgroup destruction
3859 * @cgrp: cgroup to be destroyed
3861 * css's make use of percpu refcnts whose killing latency shouldn't be
3862 * exposed to userland and are RCU protected. Also, cgroup core needs to
3863 * guarantee that css_tryget() won't succeed by the time ->css_offline() is
3864 * invoked. To satisfy all the requirements, destruction is implemented in
3865 * the following two steps.
3867 * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
3868 * userland visible parts and start killing the percpu refcnts of
3869 * css's. Set up so that the next stage will be kicked off once all
3870 * the percpu refcnts are confirmed to be killed.
3872 * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
3873 * rest of destruction. Once all cgroup references are gone, the
3874 * cgroup is RCU-freed.
3876 * This function implements s1. After this step, @cgrp is gone as far as
3877 * the userland is concerned and a new cgroup with the same name may be
3878 * created. As cgroup doesn't care about the names internally, this
3879 * doesn't cause any problem.
3881 static int cgroup_destroy_locked(struct cgroup
*cgrp
)
3882 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
3884 struct cgroup
*child
;
3885 struct cgroup_subsys_state
*css
;
3889 lockdep_assert_held(&cgroup_tree_mutex
);
3890 lockdep_assert_held(&cgroup_mutex
);
3893 * css_set_lock synchronizes access to ->cset_links and prevents
3894 * @cgrp from being removed while __put_css_set() is in progress.
3896 read_lock(&css_set_lock
);
3897 empty
= list_empty(&cgrp
->cset_links
);
3898 read_unlock(&css_set_lock
);
3903 * Make sure there's no live children. We can't test ->children
3904 * emptiness as dead children linger on it while being destroyed;
3905 * otherwise, "rmdir parent/child parent" may fail with -EBUSY.
3909 list_for_each_entry_rcu(child
, &cgrp
->children
, sibling
) {
3910 empty
= cgroup_is_dead(child
);
3919 * Initiate massacre of all css's. cgroup_destroy_css_killed()
3920 * will be invoked to perform the rest of destruction once the
3921 * percpu refs of all css's are confirmed to be killed. This
3922 * involves removing the subsystem's files, drop cgroup_mutex.
3924 mutex_unlock(&cgroup_mutex
);
3925 for_each_css(css
, ssid
, cgrp
)
3927 mutex_lock(&cgroup_mutex
);
3930 * Mark @cgrp dead. This prevents further task migration and child
3931 * creation by disabling cgroup_lock_live_group(). Note that
3932 * CGRP_DEAD assertion is depended upon by css_next_child() to
3933 * resume iteration after dropping RCU read lock. See
3934 * css_next_child() for details.
3936 set_bit(CGRP_DEAD
, &cgrp
->flags
);
3938 /* CGRP_DEAD is set, remove from ->release_list for the last time */
3939 raw_spin_lock(&release_list_lock
);
3940 if (!list_empty(&cgrp
->release_list
))
3941 list_del_init(&cgrp
->release_list
);
3942 raw_spin_unlock(&release_list_lock
);
3945 * If @cgrp has css's attached, the second stage of cgroup
3946 * destruction is kicked off from css_killed_work_fn() after the
3947 * refs of all attached css's are killed. If @cgrp doesn't have
3948 * any css, we kick it off here.
3951 cgroup_destroy_css_killed(cgrp
);
3953 /* remove @cgrp directory along with the base files */
3954 mutex_unlock(&cgroup_mutex
);
3957 * There are two control paths which try to determine cgroup from
3958 * dentry without going through kernfs - cgroupstats_build() and
3959 * css_tryget_from_dir(). Those are supported by RCU protecting
3960 * clearing of cgrp->kn->priv backpointer, which should happen
3961 * after all files under it have been removed.
3963 kernfs_remove(cgrp
->kn
); /* @cgrp has an extra ref on its kn */
3964 RCU_INIT_POINTER(*(void __rcu __force
**)&cgrp
->kn
->priv
, NULL
);
3966 mutex_lock(&cgroup_mutex
);
3972 * cgroup_destroy_css_killed - the second step of cgroup destruction
3973 * @work: cgroup->destroy_free_work
3975 * This function is invoked from a work item for a cgroup which is being
3976 * destroyed after all css's are offlined and performs the rest of
3977 * destruction. This is the second step of destruction described in the
3978 * comment above cgroup_destroy_locked().
3980 static void cgroup_destroy_css_killed(struct cgroup
*cgrp
)
3982 struct cgroup
*parent
= cgrp
->parent
;
3984 lockdep_assert_held(&cgroup_tree_mutex
);
3985 lockdep_assert_held(&cgroup_mutex
);
3987 /* delete this cgroup from parent->children */
3988 list_del_rcu(&cgrp
->sibling
);
3992 set_bit(CGRP_RELEASABLE
, &parent
->flags
);
3993 check_for_release(parent
);
3996 static int cgroup_rmdir(struct kernfs_node
*kn
)
3998 struct cgroup
*cgrp
= kn
->priv
;
4002 * This is self-destruction but @kn can't be removed while this
4003 * callback is in progress. Let's break active protection. Once
4004 * the protection is broken, @cgrp can be destroyed at any point.
4005 * Pin it so that it stays accessible.
4008 kernfs_break_active_protection(kn
);
4010 mutex_lock(&cgroup_tree_mutex
);
4011 mutex_lock(&cgroup_mutex
);
4014 * @cgrp might already have been destroyed while we're trying to
4017 if (!cgroup_is_dead(cgrp
))
4018 ret
= cgroup_destroy_locked(cgrp
);
4020 mutex_unlock(&cgroup_mutex
);
4021 mutex_unlock(&cgroup_tree_mutex
);
4023 kernfs_unbreak_active_protection(kn
);
4028 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
= {
4029 .remount_fs
= cgroup_remount
,
4030 .show_options
= cgroup_show_options
,
4031 .mkdir
= cgroup_mkdir
,
4032 .rmdir
= cgroup_rmdir
,
4033 .rename
= cgroup_rename
,
4036 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
)
4038 struct cgroup_subsys_state
*css
;
4040 printk(KERN_INFO
"Initializing cgroup subsys %s\n", ss
->name
);
4042 mutex_lock(&cgroup_tree_mutex
);
4043 mutex_lock(&cgroup_mutex
);
4045 INIT_LIST_HEAD(&ss
->cfts
);
4047 /* Create the top cgroup state for this subsystem */
4048 ss
->root
= &cgroup_dummy_root
;
4049 css
= ss
->css_alloc(cgroup_css(cgroup_dummy_top
, ss
));
4050 /* We don't handle early failures gracefully */
4051 BUG_ON(IS_ERR(css
));
4052 init_css(css
, ss
, cgroup_dummy_top
);
4054 /* Update the init_css_set to contain a subsys
4055 * pointer to this state - since the subsystem is
4056 * newly registered, all tasks and hence the
4057 * init_css_set is in the subsystem's top cgroup. */
4058 init_css_set
.subsys
[ss
->id
] = css
;
4060 need_forkexit_callback
|= ss
->fork
|| ss
->exit
;
4062 /* At system boot, before all subsystems have been
4063 * registered, no tasks have been forked, so we don't
4064 * need to invoke fork callbacks here. */
4065 BUG_ON(!list_empty(&init_task
.tasks
));
4067 BUG_ON(online_css(css
));
4069 mutex_unlock(&cgroup_mutex
);
4070 mutex_unlock(&cgroup_tree_mutex
);
4074 * cgroup_init_early - cgroup initialization at system boot
4076 * Initialize cgroups at system boot, and initialize any
4077 * subsystems that request early init.
4079 int __init
cgroup_init_early(void)
4081 struct cgroup_subsys
*ss
;
4084 atomic_set(&init_css_set
.refcount
, 1);
4085 INIT_LIST_HEAD(&init_css_set
.cgrp_links
);
4086 INIT_LIST_HEAD(&init_css_set
.tasks
);
4087 INIT_HLIST_NODE(&init_css_set
.hlist
);
4089 init_cgroup_root(&cgroup_dummy_root
);
4090 cgroup_root_count
= 1;
4091 RCU_INIT_POINTER(init_task
.cgroups
, &init_css_set
);
4093 init_cgrp_cset_link
.cset
= &init_css_set
;
4094 init_cgrp_cset_link
.cgrp
= cgroup_dummy_top
;
4095 list_add(&init_cgrp_cset_link
.cset_link
, &cgroup_dummy_top
->cset_links
);
4096 list_add(&init_cgrp_cset_link
.cgrp_link
, &init_css_set
.cgrp_links
);
4098 for_each_subsys(ss
, i
) {
4099 WARN(!ss
->css_alloc
|| !ss
->css_free
|| ss
->name
|| ss
->id
,
4100 "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n",
4101 i
, cgroup_subsys_name
[i
], ss
->css_alloc
, ss
->css_free
,
4103 WARN(strlen(cgroup_subsys_name
[i
]) > MAX_CGROUP_TYPE_NAMELEN
,
4104 "cgroup_subsys_name %s too long\n", cgroup_subsys_name
[i
]);
4107 ss
->name
= cgroup_subsys_name
[i
];
4110 cgroup_init_subsys(ss
);
4116 * cgroup_init - cgroup initialization
4118 * Register cgroup filesystem and /proc file, and initialize
4119 * any subsystems that didn't request early init.
4121 int __init
cgroup_init(void)
4123 struct cgroup_subsys
*ss
;
4127 BUG_ON(cgroup_init_cftypes(NULL
, cgroup_base_files
));
4129 for_each_subsys(ss
, i
) {
4130 if (!ss
->early_init
)
4131 cgroup_init_subsys(ss
);
4134 * cftype registration needs kmalloc and can't be done
4135 * during early_init. Register base cftypes separately.
4137 if (ss
->base_cftypes
)
4138 WARN_ON(cgroup_add_cftypes(ss
, ss
->base_cftypes
));
4141 /* allocate id for the dummy hierarchy */
4142 mutex_lock(&cgroup_mutex
);
4144 /* Add init_css_set to the hash table */
4145 key
= css_set_hash(init_css_set
.subsys
);
4146 hash_add(css_set_table
, &init_css_set
.hlist
, key
);
4148 BUG_ON(cgroup_init_root_id(&cgroup_dummy_root
, 0, 1));
4150 err
= idr_alloc(&cgroup_dummy_root
.cgroup_idr
, cgroup_dummy_top
,
4154 mutex_unlock(&cgroup_mutex
);
4156 cgroup_kobj
= kobject_create_and_add("cgroup", fs_kobj
);
4160 err
= register_filesystem(&cgroup_fs_type
);
4162 kobject_put(cgroup_kobj
);
4166 proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
);
4170 static int __init
cgroup_wq_init(void)
4173 * There isn't much point in executing destruction path in
4174 * parallel. Good chunk is serialized with cgroup_mutex anyway.
4176 * XXX: Must be ordered to make sure parent is offlined after
4177 * children. The ordering requirement is for memcg where a
4178 * parent's offline may wait for a child's leading to deadlock. In
4179 * the long term, this should be fixed from memcg side.
4181 * We would prefer to do this in cgroup_init() above, but that
4182 * is called before init_workqueues(): so leave this until after.
4184 cgroup_destroy_wq
= alloc_ordered_workqueue("cgroup_destroy", 0);
4185 BUG_ON(!cgroup_destroy_wq
);
4188 * Used to destroy pidlists and separate to serve as flush domain.
4189 * Cap @max_active to 1 too.
4191 cgroup_pidlist_destroy_wq
= alloc_workqueue("cgroup_pidlist_destroy",
4193 BUG_ON(!cgroup_pidlist_destroy_wq
);
4197 core_initcall(cgroup_wq_init
);
4200 * proc_cgroup_show()
4201 * - Print task's cgroup paths into seq_file, one line for each hierarchy
4202 * - Used for /proc/<pid>/cgroup.
4203 * - No need to task_lock(tsk) on this tsk->cgroup reference, as it
4204 * doesn't really matter if tsk->cgroup changes after we read it,
4205 * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it
4206 * anyway. No need to check that tsk->cgroup != NULL, thanks to
4207 * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks
4208 * cgroup to top_cgroup.
4211 /* TODO: Use a proper seq_file iterator */
4212 int proc_cgroup_show(struct seq_file
*m
, void *v
)
4215 struct task_struct
*tsk
;
4218 struct cgroupfs_root
*root
;
4221 buf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
4227 tsk
= get_pid_task(pid
, PIDTYPE_PID
);
4233 mutex_lock(&cgroup_mutex
);
4235 for_each_active_root(root
) {
4236 struct cgroup_subsys
*ss
;
4237 struct cgroup
*cgrp
;
4238 int ssid
, count
= 0;
4240 seq_printf(m
, "%d:", root
->hierarchy_id
);
4241 for_each_subsys(ss
, ssid
)
4242 if (root
->subsys_mask
& (1 << ssid
))
4243 seq_printf(m
, "%s%s", count
++ ? "," : "", ss
->name
);
4244 if (strlen(root
->name
))
4245 seq_printf(m
, "%sname=%s", count
? "," : "",
4248 cgrp
= task_cgroup_from_root(tsk
, root
);
4249 path
= cgroup_path(cgrp
, buf
, PATH_MAX
);
4251 retval
= -ENAMETOOLONG
;
4259 mutex_unlock(&cgroup_mutex
);
4260 put_task_struct(tsk
);
4267 /* Display information about each subsystem and each hierarchy */
4268 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
4270 struct cgroup_subsys
*ss
;
4273 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
4275 * ideally we don't want subsystems moving around while we do this.
4276 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
4277 * subsys/hierarchy state.
4279 mutex_lock(&cgroup_mutex
);
4281 for_each_subsys(ss
, i
)
4282 seq_printf(m
, "%s\t%d\t%d\t%d\n",
4283 ss
->name
, ss
->root
->hierarchy_id
,
4284 ss
->root
->number_of_cgroups
, !ss
->disabled
);
4286 mutex_unlock(&cgroup_mutex
);
4290 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
4292 return single_open(file
, proc_cgroupstats_show
, NULL
);
4295 static const struct file_operations proc_cgroupstats_operations
= {
4296 .open
= cgroupstats_open
,
4298 .llseek
= seq_lseek
,
4299 .release
= single_release
,
4303 * cgroup_fork - attach newly forked task to its parents cgroup.
4304 * @child: pointer to task_struct of forking parent process.
4306 * Description: A task inherits its parent's cgroup at fork().
4308 * A pointer to the shared css_set was automatically copied in
4309 * fork.c by dup_task_struct(). However, we ignore that copy, since
4310 * it was not made under the protection of RCU or cgroup_mutex, so
4311 * might no longer be a valid cgroup pointer. cgroup_attach_task() might
4312 * have already changed current->cgroups, allowing the previously
4313 * referenced cgroup group to be removed and freed.
4315 * At the point that cgroup_fork() is called, 'current' is the parent
4316 * task, and the passed argument 'child' points to the child task.
4318 void cgroup_fork(struct task_struct
*child
)
4321 get_css_set(task_css_set(current
));
4322 child
->cgroups
= current
->cgroups
;
4323 task_unlock(current
);
4324 INIT_LIST_HEAD(&child
->cg_list
);
4328 * cgroup_post_fork - called on a new task after adding it to the task list
4329 * @child: the task in question
4331 * Adds the task to the list running through its css_set if necessary and
4332 * call the subsystem fork() callbacks. Has to be after the task is
4333 * visible on the task list in case we race with the first call to
4334 * cgroup_task_iter_start() - to guarantee that the new task ends up on its
4337 void cgroup_post_fork(struct task_struct
*child
)
4339 struct cgroup_subsys
*ss
;
4343 * use_task_css_set_links is set to 1 before we walk the tasklist
4344 * under the tasklist_lock and we read it here after we added the child
4345 * to the tasklist under the tasklist_lock as well. If the child wasn't
4346 * yet in the tasklist when we walked through it from
4347 * cgroup_enable_task_cg_lists(), then use_task_css_set_links value
4348 * should be visible now due to the paired locking and barriers implied
4349 * by LOCK/UNLOCK: it is written before the tasklist_lock unlock
4350 * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
4353 if (use_task_css_set_links
) {
4354 write_lock(&css_set_lock
);
4356 if (list_empty(&child
->cg_list
))
4357 list_add(&child
->cg_list
, &task_css_set(child
)->tasks
);
4359 write_unlock(&css_set_lock
);
4363 * Call ss->fork(). This must happen after @child is linked on
4364 * css_set; otherwise, @child might change state between ->fork()
4365 * and addition to css_set.
4367 if (need_forkexit_callback
) {
4368 for_each_subsys(ss
, i
)
4375 * cgroup_exit - detach cgroup from exiting task
4376 * @tsk: pointer to task_struct of exiting process
4377 * @run_callback: run exit callbacks?
4379 * Description: Detach cgroup from @tsk and release it.
4381 * Note that cgroups marked notify_on_release force every task in
4382 * them to take the global cgroup_mutex mutex when exiting.
4383 * This could impact scaling on very large systems. Be reluctant to
4384 * use notify_on_release cgroups where very high task exit scaling
4385 * is required on large systems.
4387 * the_top_cgroup_hack:
4389 * Set the exiting tasks cgroup to the root cgroup (top_cgroup).
4391 * We call cgroup_exit() while the task is still competent to
4392 * handle notify_on_release(), then leave the task attached to the
4393 * root cgroup in each hierarchy for the remainder of its exit.
4395 * To do this properly, we would increment the reference count on
4396 * top_cgroup, and near the very end of the kernel/exit.c do_exit()
4397 * code we would add a second cgroup function call, to drop that
4398 * reference. This would just create an unnecessary hot spot on
4399 * the top_cgroup reference count, to no avail.
4401 * Normally, holding a reference to a cgroup without bumping its
4402 * count is unsafe. The cgroup could go away, or someone could
4403 * attach us to a different cgroup, decrementing the count on
4404 * the first cgroup that we never incremented. But in this case,
4405 * top_cgroup isn't going away, and either task has PF_EXITING set,
4406 * which wards off any cgroup_attach_task() attempts, or task is a failed
4407 * fork, never visible to cgroup_attach_task.
4409 void cgroup_exit(struct task_struct
*tsk
, int run_callbacks
)
4411 struct cgroup_subsys
*ss
;
4412 struct css_set
*cset
;
4416 * Unlink from the css_set task list if necessary.
4417 * Optimistically check cg_list before taking
4420 if (!list_empty(&tsk
->cg_list
)) {
4421 write_lock(&css_set_lock
);
4422 if (!list_empty(&tsk
->cg_list
))
4423 list_del_init(&tsk
->cg_list
);
4424 write_unlock(&css_set_lock
);
4427 /* Reassign the task to the init_css_set. */
4429 cset
= task_css_set(tsk
);
4430 RCU_INIT_POINTER(tsk
->cgroups
, &init_css_set
);
4432 if (run_callbacks
&& need_forkexit_callback
) {
4433 /* see cgroup_post_fork() for details */
4434 for_each_subsys(ss
, i
) {
4436 struct cgroup_subsys_state
*old_css
= cset
->subsys
[i
];
4437 struct cgroup_subsys_state
*css
= task_css(tsk
, i
);
4439 ss
->exit(css
, old_css
, tsk
);
4445 put_css_set_taskexit(cset
);
4448 static void check_for_release(struct cgroup
*cgrp
)
4450 if (cgroup_is_releasable(cgrp
) &&
4451 list_empty(&cgrp
->cset_links
) && list_empty(&cgrp
->children
)) {
4453 * Control Group is currently removeable. If it's not
4454 * already queued for a userspace notification, queue
4457 int need_schedule_work
= 0;
4459 raw_spin_lock(&release_list_lock
);
4460 if (!cgroup_is_dead(cgrp
) &&
4461 list_empty(&cgrp
->release_list
)) {
4462 list_add(&cgrp
->release_list
, &release_list
);
4463 need_schedule_work
= 1;
4465 raw_spin_unlock(&release_list_lock
);
4466 if (need_schedule_work
)
4467 schedule_work(&release_agent_work
);
4472 * Notify userspace when a cgroup is released, by running the
4473 * configured release agent with the name of the cgroup (path
4474 * relative to the root of cgroup file system) as the argument.
4476 * Most likely, this user command will try to rmdir this cgroup.
4478 * This races with the possibility that some other task will be
4479 * attached to this cgroup before it is removed, or that some other
4480 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
4481 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
4482 * unused, and this cgroup will be reprieved from its death sentence,
4483 * to continue to serve a useful existence. Next time it's released,
4484 * we will get notified again, if it still has 'notify_on_release' set.
4486 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
4487 * means only wait until the task is successfully execve()'d. The
4488 * separate release agent task is forked by call_usermodehelper(),
4489 * then control in this thread returns here, without waiting for the
4490 * release agent task. We don't bother to wait because the caller of
4491 * this routine has no use for the exit status of the release agent
4492 * task, so no sense holding our caller up for that.
4494 static void cgroup_release_agent(struct work_struct
*work
)
4496 BUG_ON(work
!= &release_agent_work
);
4497 mutex_lock(&cgroup_mutex
);
4498 raw_spin_lock(&release_list_lock
);
4499 while (!list_empty(&release_list
)) {
4500 char *argv
[3], *envp
[3];
4502 char *pathbuf
= NULL
, *agentbuf
= NULL
, *path
;
4503 struct cgroup
*cgrp
= list_entry(release_list
.next
,
4506 list_del_init(&cgrp
->release_list
);
4507 raw_spin_unlock(&release_list_lock
);
4508 pathbuf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
4511 path
= cgroup_path(cgrp
, pathbuf
, PATH_MAX
);
4514 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
4519 argv
[i
++] = agentbuf
;
4524 /* minimal command environment */
4525 envp
[i
++] = "HOME=/";
4526 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
4529 /* Drop the lock while we invoke the usermode helper,
4530 * since the exec could involve hitting disk and hence
4531 * be a slow process */
4532 mutex_unlock(&cgroup_mutex
);
4533 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
4534 mutex_lock(&cgroup_mutex
);
4538 raw_spin_lock(&release_list_lock
);
4540 raw_spin_unlock(&release_list_lock
);
4541 mutex_unlock(&cgroup_mutex
);
4544 static int __init
cgroup_disable(char *str
)
4546 struct cgroup_subsys
*ss
;
4550 while ((token
= strsep(&str
, ",")) != NULL
) {
4554 for_each_subsys(ss
, i
) {
4555 if (!strcmp(token
, ss
->name
)) {
4557 printk(KERN_INFO
"Disabling %s control group"
4558 " subsystem\n", ss
->name
);
4565 __setup("cgroup_disable=", cgroup_disable
);
4568 * css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir
4569 * @dentry: directory dentry of interest
4570 * @ss: subsystem of interest
4572 * If @dentry is a directory for a cgroup which has @ss enabled on it, try
4573 * to get the corresponding css and return it. If such css doesn't exist
4574 * or can't be pinned, an ERR_PTR value is returned.
4576 struct cgroup_subsys_state
*css_tryget_from_dir(struct dentry
*dentry
,
4577 struct cgroup_subsys
*ss
)
4579 struct kernfs_node
*kn
= kernfs_node_from_dentry(dentry
);
4580 struct cgroup_subsys_state
*css
= NULL
;
4581 struct cgroup
*cgrp
;
4583 /* is @dentry a cgroup dir? */
4584 if (dentry
->d_sb
->s_type
!= &cgroup_fs_type
|| !kn
||
4585 kernfs_type(kn
) != KERNFS_DIR
)
4586 return ERR_PTR(-EBADF
);
4591 * This path doesn't originate from kernfs and @kn could already
4592 * have been or be removed at any point. @kn->priv is RCU
4593 * protected for this access. See destroy_locked() for details.
4595 cgrp
= rcu_dereference(kn
->priv
);
4597 css
= cgroup_css(cgrp
, ss
);
4599 if (!css
|| !css_tryget(css
))
4600 css
= ERR_PTR(-ENOENT
);
4607 * css_from_id - lookup css by id
4608 * @id: the cgroup id
4609 * @ss: cgroup subsys to be looked into
4611 * Returns the css if there's valid one with @id, otherwise returns NULL.
4612 * Should be called under rcu_read_lock().
4614 struct cgroup_subsys_state
*css_from_id(int id
, struct cgroup_subsys
*ss
)
4616 struct cgroup
*cgrp
;
4618 cgroup_assert_mutexes_or_rcu_locked();
4620 cgrp
= idr_find(&ss
->root
->cgroup_idr
, id
);
4622 return cgroup_css(cgrp
, ss
);
4626 #ifdef CONFIG_CGROUP_DEBUG
4627 static struct cgroup_subsys_state
*
4628 debug_css_alloc(struct cgroup_subsys_state
*parent_css
)
4630 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
4633 return ERR_PTR(-ENOMEM
);
4638 static void debug_css_free(struct cgroup_subsys_state
*css
)
4643 static u64
debug_taskcount_read(struct cgroup_subsys_state
*css
,
4646 return cgroup_task_count(css
->cgroup
);
4649 static u64
current_css_set_read(struct cgroup_subsys_state
*css
,
4652 return (u64
)(unsigned long)current
->cgroups
;
4655 static u64
current_css_set_refcount_read(struct cgroup_subsys_state
*css
,
4661 count
= atomic_read(&task_css_set(current
)->refcount
);
4666 static int current_css_set_cg_links_read(struct seq_file
*seq
, void *v
)
4668 struct cgrp_cset_link
*link
;
4669 struct css_set
*cset
;
4672 name_buf
= kmalloc(NAME_MAX
+ 1, GFP_KERNEL
);
4676 read_lock(&css_set_lock
);
4678 cset
= rcu_dereference(current
->cgroups
);
4679 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
4680 struct cgroup
*c
= link
->cgrp
;
4681 const char *name
= "?";
4683 if (c
!= cgroup_dummy_top
) {
4684 cgroup_name(c
, name_buf
, NAME_MAX
+ 1);
4688 seq_printf(seq
, "Root %d group %s\n",
4689 c
->root
->hierarchy_id
, name
);
4692 read_unlock(&css_set_lock
);
4697 #define MAX_TASKS_SHOWN_PER_CSS 25
4698 static int cgroup_css_links_read(struct seq_file
*seq
, void *v
)
4700 struct cgroup_subsys_state
*css
= seq_css(seq
);
4701 struct cgrp_cset_link
*link
;
4703 read_lock(&css_set_lock
);
4704 list_for_each_entry(link
, &css
->cgroup
->cset_links
, cset_link
) {
4705 struct css_set
*cset
= link
->cset
;
4706 struct task_struct
*task
;
4708 seq_printf(seq
, "css_set %p\n", cset
);
4709 list_for_each_entry(task
, &cset
->tasks
, cg_list
) {
4710 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
) {
4711 seq_puts(seq
, " ...\n");
4714 seq_printf(seq
, " task %d\n",
4715 task_pid_vnr(task
));
4719 read_unlock(&css_set_lock
);
4723 static u64
releasable_read(struct cgroup_subsys_state
*css
, struct cftype
*cft
)
4725 return test_bit(CGRP_RELEASABLE
, &css
->cgroup
->flags
);
4728 static struct cftype debug_files
[] = {
4730 .name
= "taskcount",
4731 .read_u64
= debug_taskcount_read
,
4735 .name
= "current_css_set",
4736 .read_u64
= current_css_set_read
,
4740 .name
= "current_css_set_refcount",
4741 .read_u64
= current_css_set_refcount_read
,
4745 .name
= "current_css_set_cg_links",
4746 .seq_show
= current_css_set_cg_links_read
,
4750 .name
= "cgroup_css_links",
4751 .seq_show
= cgroup_css_links_read
,
4755 .name
= "releasable",
4756 .read_u64
= releasable_read
,
4762 struct cgroup_subsys debug_cgrp_subsys
= {
4763 .css_alloc
= debug_css_alloc
,
4764 .css_free
= debug_css_free
,
4765 .base_cftypes
= debug_files
,
4767 #endif /* CONFIG_CGROUP_DEBUG */