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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31 #include <linux/cgroup.h>
32 #include <linux/cred.h>
33 #include <linux/ctype.h>
34 #include <linux/errno.h>
35 #include <linux/init_task.h>
36 #include <linux/kernel.h>
37 #include <linux/list.h>
38 #include <linux/magic.h>
40 #include <linux/mutex.h>
41 #include <linux/mount.h>
42 #include <linux/pagemap.h>
43 #include <linux/proc_fs.h>
44 #include <linux/rcupdate.h>
45 #include <linux/sched.h>
46 #include <linux/slab.h>
47 #include <linux/spinlock.h>
48 #include <linux/percpu-rwsem.h>
49 #include <linux/string.h>
50 #include <linux/sort.h>
51 #include <linux/kmod.h>
52 #include <linux/delayacct.h>
53 #include <linux/cgroupstats.h>
54 #include <linux/hashtable.h>
55 #include <linux/pid_namespace.h>
56 #include <linux/idr.h>
57 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
58 #include <linux/kthread.h>
59 #include <linux/delay.h>
60 #include <linux/atomic.h>
61 #include <linux/cpuset.h>
65 * pidlists linger the following amount before being destroyed. The goal
66 * is avoiding frequent destruction in the middle of consecutive read calls
67 * Expiring in the middle is a performance problem not a correctness one.
68 * 1 sec should be enough.
70 #define CGROUP_PIDLIST_DESTROY_DELAY HZ
72 #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
76 * cgroup_mutex is the master lock. Any modification to cgroup or its
77 * hierarchy must be performed while holding it.
79 * css_set_lock protects task->cgroups pointer, the list of css_set
80 * objects, and the chain of tasks off each css_set.
82 * These locks are exported if CONFIG_PROVE_RCU so that accessors in
83 * cgroup.h can use them for lockdep annotations.
85 #ifdef CONFIG_PROVE_RCU
86 DEFINE_MUTEX(cgroup_mutex
);
87 DEFINE_SPINLOCK(css_set_lock
);
88 EXPORT_SYMBOL_GPL(cgroup_mutex
);
89 EXPORT_SYMBOL_GPL(css_set_lock
);
91 static DEFINE_MUTEX(cgroup_mutex
);
92 static DEFINE_SPINLOCK(css_set_lock
);
96 * Protects cgroup_idr and css_idr so that IDs can be released without
97 * grabbing cgroup_mutex.
99 static DEFINE_SPINLOCK(cgroup_idr_lock
);
102 * Protects cgroup_file->kn for !self csses. It synchronizes notifications
103 * against file removal/re-creation across css hiding.
105 static DEFINE_SPINLOCK(cgroup_file_kn_lock
);
108 * Protects cgroup_subsys->release_agent_path. Modifying it also requires
109 * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
111 static DEFINE_SPINLOCK(release_agent_path_lock
);
113 struct percpu_rw_semaphore cgroup_threadgroup_rwsem
;
115 #define cgroup_assert_mutex_or_rcu_locked() \
116 RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
117 !lockdep_is_held(&cgroup_mutex), \
118 "cgroup_mutex or RCU read lock required");
121 * cgroup destruction makes heavy use of work items and there can be a lot
122 * of concurrent destructions. Use a separate workqueue so that cgroup
123 * destruction work items don't end up filling up max_active of system_wq
124 * which may lead to deadlock.
126 static struct workqueue_struct
*cgroup_destroy_wq
;
129 * pidlist destructions need to be flushed on cgroup destruction. Use a
130 * separate workqueue as flush domain.
132 static struct workqueue_struct
*cgroup_pidlist_destroy_wq
;
134 /* generate an array of cgroup subsystem pointers */
135 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
136 static struct cgroup_subsys
*cgroup_subsys
[] = {
137 #include <linux/cgroup_subsys.h>
141 /* array of cgroup subsystem names */
142 #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
143 static const char *cgroup_subsys_name
[] = {
144 #include <linux/cgroup_subsys.h>
148 /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
150 DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
151 DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
152 EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
153 EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
154 #include <linux/cgroup_subsys.h>
157 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
158 static struct static_key_true
*cgroup_subsys_enabled_key
[] = {
159 #include <linux/cgroup_subsys.h>
163 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
164 static struct static_key_true
*cgroup_subsys_on_dfl_key
[] = {
165 #include <linux/cgroup_subsys.h>
170 * The default hierarchy, reserved for the subsystems that are otherwise
171 * unattached - it never has more than a single cgroup, and all tasks are
172 * part of that cgroup.
174 struct cgroup_root cgrp_dfl_root
;
175 EXPORT_SYMBOL_GPL(cgrp_dfl_root
);
178 * The default hierarchy always exists but is hidden until mounted for the
179 * first time. This is for backward compatibility.
181 static bool cgrp_dfl_visible
;
183 /* Controllers blocked by the commandline in v1 */
184 static u16 cgroup_no_v1_mask
;
186 /* some controllers are not supported in the default hierarchy */
187 static u16 cgrp_dfl_inhibit_ss_mask
;
189 /* some controllers are implicitly enabled on the default hierarchy */
190 static unsigned long cgrp_dfl_implicit_ss_mask
;
192 /* The list of hierarchy roots */
194 static LIST_HEAD(cgroup_roots
);
195 static int cgroup_root_count
;
197 /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
198 static DEFINE_IDR(cgroup_hierarchy_idr
);
201 * Assign a monotonically increasing serial number to csses. It guarantees
202 * cgroups with bigger numbers are newer than those with smaller numbers.
203 * Also, as csses are always appended to the parent's ->children list, it
204 * guarantees that sibling csses are always sorted in the ascending serial
205 * number order on the list. Protected by cgroup_mutex.
207 static u64 css_serial_nr_next
= 1;
210 * These bitmask flags indicate whether tasks in the fork and exit paths have
211 * fork/exit handlers to call. This avoids us having to do extra work in the
212 * fork/exit path to check which subsystems have fork/exit callbacks.
214 static u16 have_fork_callback __read_mostly
;
215 static u16 have_exit_callback __read_mostly
;
216 static u16 have_free_callback __read_mostly
;
218 /* Ditto for the can_fork callback. */
219 static u16 have_canfork_callback __read_mostly
;
221 static struct file_system_type cgroup2_fs_type
;
222 static struct cftype cgroup_dfl_base_files
[];
223 static struct cftype cgroup_legacy_base_files
[];
225 static int rebind_subsystems(struct cgroup_root
*dst_root
, u16 ss_mask
);
226 static void cgroup_lock_and_drain_offline(struct cgroup
*cgrp
);
227 static int cgroup_apply_control(struct cgroup
*cgrp
);
228 static void cgroup_finalize_control(struct cgroup
*cgrp
, int ret
);
229 static void css_task_iter_advance(struct css_task_iter
*it
);
230 static int cgroup_destroy_locked(struct cgroup
*cgrp
);
231 static struct cgroup_subsys_state
*css_create(struct cgroup
*cgrp
,
232 struct cgroup_subsys
*ss
);
233 static void css_release(struct percpu_ref
*ref
);
234 static void kill_css(struct cgroup_subsys_state
*css
);
235 static int cgroup_addrm_files(struct cgroup_subsys_state
*css
,
236 struct cgroup
*cgrp
, struct cftype cfts
[],
240 * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
241 * @ssid: subsys ID of interest
243 * cgroup_subsys_enabled() can only be used with literal subsys names which
244 * is fine for individual subsystems but unsuitable for cgroup core. This
245 * is slower static_key_enabled() based test indexed by @ssid.
247 static bool cgroup_ssid_enabled(int ssid
)
249 return static_key_enabled(cgroup_subsys_enabled_key
[ssid
]);
252 static bool cgroup_ssid_no_v1(int ssid
)
254 return cgroup_no_v1_mask
& (1 << ssid
);
258 * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
259 * @cgrp: the cgroup of interest
261 * The default hierarchy is the v2 interface of cgroup and this function
262 * can be used to test whether a cgroup is on the default hierarchy for
263 * cases where a subsystem should behave differnetly depending on the
266 * The set of behaviors which change on the default hierarchy are still
267 * being determined and the mount option is prefixed with __DEVEL__.
269 * List of changed behaviors:
271 * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
272 * and "name" are disallowed.
274 * - When mounting an existing superblock, mount options should match.
276 * - Remount is disallowed.
278 * - rename(2) is disallowed.
280 * - "tasks" is removed. Everything should be at process granularity. Use
281 * "cgroup.procs" instead.
283 * - "cgroup.procs" is not sorted. pids will be unique unless they got
284 * recycled inbetween reads.
286 * - "release_agent" and "notify_on_release" are removed. Replacement
287 * notification mechanism will be implemented.
289 * - "cgroup.clone_children" is removed.
291 * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
292 * and its descendants contain no task; otherwise, 1. The file also
293 * generates kernfs notification which can be monitored through poll and
294 * [di]notify when the value of the file changes.
296 * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
297 * take masks of ancestors with non-empty cpus/mems, instead of being
298 * moved to an ancestor.
300 * - cpuset: a task can be moved into an empty cpuset, and again it takes
301 * masks of ancestors.
303 * - memcg: use_hierarchy is on by default and the cgroup file for the flag
306 * - blkcg: blk-throttle becomes properly hierarchical.
308 * - debug: disallowed on the default hierarchy.
310 static bool cgroup_on_dfl(const struct cgroup
*cgrp
)
312 return cgrp
->root
== &cgrp_dfl_root
;
315 /* IDR wrappers which synchronize using cgroup_idr_lock */
316 static int cgroup_idr_alloc(struct idr
*idr
, void *ptr
, int start
, int end
,
321 idr_preload(gfp_mask
);
322 spin_lock_bh(&cgroup_idr_lock
);
323 ret
= idr_alloc(idr
, ptr
, start
, end
, gfp_mask
& ~__GFP_DIRECT_RECLAIM
);
324 spin_unlock_bh(&cgroup_idr_lock
);
329 static void *cgroup_idr_replace(struct idr
*idr
, void *ptr
, int id
)
333 spin_lock_bh(&cgroup_idr_lock
);
334 ret
= idr_replace(idr
, ptr
, id
);
335 spin_unlock_bh(&cgroup_idr_lock
);
339 static void cgroup_idr_remove(struct idr
*idr
, int id
)
341 spin_lock_bh(&cgroup_idr_lock
);
343 spin_unlock_bh(&cgroup_idr_lock
);
346 static struct cgroup
*cgroup_parent(struct cgroup
*cgrp
)
348 struct cgroup_subsys_state
*parent_css
= cgrp
->self
.parent
;
351 return container_of(parent_css
, struct cgroup
, self
);
355 /* subsystems visibly enabled on a cgroup */
356 static u16
cgroup_control(struct cgroup
*cgrp
)
358 struct cgroup
*parent
= cgroup_parent(cgrp
);
359 u16 root_ss_mask
= cgrp
->root
->subsys_mask
;
362 return parent
->subtree_control
;
364 if (cgroup_on_dfl(cgrp
))
365 root_ss_mask
&= ~(cgrp_dfl_inhibit_ss_mask
|
366 cgrp_dfl_implicit_ss_mask
);
370 /* subsystems enabled on a cgroup */
371 static u16
cgroup_ss_mask(struct cgroup
*cgrp
)
373 struct cgroup
*parent
= cgroup_parent(cgrp
);
376 return parent
->subtree_ss_mask
;
378 return cgrp
->root
->subsys_mask
;
382 * cgroup_css - obtain a cgroup's css for the specified subsystem
383 * @cgrp: the cgroup of interest
384 * @ss: the subsystem of interest (%NULL returns @cgrp->self)
386 * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
387 * function must be called either under cgroup_mutex or rcu_read_lock() and
388 * the caller is responsible for pinning the returned css if it wants to
389 * keep accessing it outside the said locks. This function may return
390 * %NULL if @cgrp doesn't have @subsys_id enabled.
392 static struct cgroup_subsys_state
*cgroup_css(struct cgroup
*cgrp
,
393 struct cgroup_subsys
*ss
)
396 return rcu_dereference_check(cgrp
->subsys
[ss
->id
],
397 lockdep_is_held(&cgroup_mutex
));
403 * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
404 * @cgrp: the cgroup of interest
405 * @ss: the subsystem of interest (%NULL returns @cgrp->self)
407 * Similar to cgroup_css() but returns the effective css, which is defined
408 * as the matching css of the nearest ancestor including self which has @ss
409 * enabled. If @ss is associated with the hierarchy @cgrp is on, this
410 * function is guaranteed to return non-NULL css.
412 static struct cgroup_subsys_state
*cgroup_e_css(struct cgroup
*cgrp
,
413 struct cgroup_subsys
*ss
)
415 lockdep_assert_held(&cgroup_mutex
);
421 * This function is used while updating css associations and thus
422 * can't test the csses directly. Test ss_mask.
424 while (!(cgroup_ss_mask(cgrp
) & (1 << ss
->id
))) {
425 cgrp
= cgroup_parent(cgrp
);
430 return cgroup_css(cgrp
, ss
);
434 * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
435 * @cgrp: the cgroup of interest
436 * @ss: the subsystem of interest
438 * Find and get the effective css of @cgrp for @ss. The effective css is
439 * defined as the matching css of the nearest ancestor including self which
440 * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
441 * the root css is returned, so this function always returns a valid css.
442 * The returned css must be put using css_put().
444 struct cgroup_subsys_state
*cgroup_get_e_css(struct cgroup
*cgrp
,
445 struct cgroup_subsys
*ss
)
447 struct cgroup_subsys_state
*css
;
452 css
= cgroup_css(cgrp
, ss
);
454 if (css
&& css_tryget_online(css
))
456 cgrp
= cgroup_parent(cgrp
);
459 css
= init_css_set
.subsys
[ss
->id
];
466 /* convenient tests for these bits */
467 static inline bool cgroup_is_dead(const struct cgroup
*cgrp
)
469 return !(cgrp
->self
.flags
& CSS_ONLINE
);
472 static void cgroup_get(struct cgroup
*cgrp
)
474 WARN_ON_ONCE(cgroup_is_dead(cgrp
));
475 css_get(&cgrp
->self
);
478 static bool cgroup_tryget(struct cgroup
*cgrp
)
480 return css_tryget(&cgrp
->self
);
483 struct cgroup_subsys_state
*of_css(struct kernfs_open_file
*of
)
485 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
486 struct cftype
*cft
= of_cft(of
);
489 * This is open and unprotected implementation of cgroup_css().
490 * seq_css() is only called from a kernfs file operation which has
491 * an active reference on the file. Because all the subsystem
492 * files are drained before a css is disassociated with a cgroup,
493 * the matching css from the cgroup's subsys table is guaranteed to
494 * be and stay valid until the enclosing operation is complete.
497 return rcu_dereference_raw(cgrp
->subsys
[cft
->ss
->id
]);
501 EXPORT_SYMBOL_GPL(of_css
);
503 static int notify_on_release(const struct cgroup
*cgrp
)
505 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
509 * for_each_css - iterate all css's of a cgroup
510 * @css: the iteration cursor
511 * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
512 * @cgrp: the target cgroup to iterate css's of
514 * Should be called under cgroup_[tree_]mutex.
516 #define for_each_css(css, ssid, cgrp) \
517 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
518 if (!((css) = rcu_dereference_check( \
519 (cgrp)->subsys[(ssid)], \
520 lockdep_is_held(&cgroup_mutex)))) { } \
524 * for_each_e_css - iterate all effective css's of a cgroup
525 * @css: the iteration cursor
526 * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
527 * @cgrp: the target cgroup to iterate css's of
529 * Should be called under cgroup_[tree_]mutex.
531 #define for_each_e_css(css, ssid, cgrp) \
532 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
533 if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
538 * for_each_subsys - iterate all enabled cgroup subsystems
539 * @ss: the iteration cursor
540 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
542 #define for_each_subsys(ss, ssid) \
543 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
544 (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
547 * do_each_subsys_mask - filter for_each_subsys with a bitmask
548 * @ss: the iteration cursor
549 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
550 * @ss_mask: the bitmask
552 * The block will only run for cases where the ssid-th bit (1 << ssid) of
555 #define do_each_subsys_mask(ss, ssid, ss_mask) do { \
556 unsigned long __ss_mask = (ss_mask); \
557 if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
561 for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
562 (ss) = cgroup_subsys[ssid]; \
565 #define while_each_subsys_mask() \
570 /* iterate across the hierarchies */
571 #define for_each_root(root) \
572 list_for_each_entry((root), &cgroup_roots, root_list)
574 /* iterate over child cgrps, lock should be held throughout iteration */
575 #define cgroup_for_each_live_child(child, cgrp) \
576 list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
577 if (({ lockdep_assert_held(&cgroup_mutex); \
578 cgroup_is_dead(child); })) \
582 /* walk live descendants in preorder */
583 #define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
584 css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
585 if (({ lockdep_assert_held(&cgroup_mutex); \
586 (dsct) = (d_css)->cgroup; \
587 cgroup_is_dead(dsct); })) \
591 /* walk live descendants in postorder */
592 #define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
593 css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
594 if (({ lockdep_assert_held(&cgroup_mutex); \
595 (dsct) = (d_css)->cgroup; \
596 cgroup_is_dead(dsct); })) \
600 static void cgroup_release_agent(struct work_struct
*work
);
601 static void check_for_release(struct cgroup
*cgrp
);
604 * A cgroup can be associated with multiple css_sets as different tasks may
605 * belong to different cgroups on different hierarchies. In the other
606 * direction, a css_set is naturally associated with multiple cgroups.
607 * This M:N relationship is represented by the following link structure
608 * which exists for each association and allows traversing the associations
611 struct cgrp_cset_link
{
612 /* the cgroup and css_set this link associates */
614 struct css_set
*cset
;
616 /* list of cgrp_cset_links anchored at cgrp->cset_links */
617 struct list_head cset_link
;
619 /* list of cgrp_cset_links anchored at css_set->cgrp_links */
620 struct list_head cgrp_link
;
624 * The default css_set - used by init and its children prior to any
625 * hierarchies being mounted. It contains a pointer to the root state
626 * for each subsystem. Also used to anchor the list of css_sets. Not
627 * reference-counted, to improve performance when child cgroups
628 * haven't been created.
630 struct css_set init_css_set
= {
631 .refcount
= ATOMIC_INIT(1),
632 .cgrp_links
= LIST_HEAD_INIT(init_css_set
.cgrp_links
),
633 .tasks
= LIST_HEAD_INIT(init_css_set
.tasks
),
634 .mg_tasks
= LIST_HEAD_INIT(init_css_set
.mg_tasks
),
635 .mg_preload_node
= LIST_HEAD_INIT(init_css_set
.mg_preload_node
),
636 .mg_node
= LIST_HEAD_INIT(init_css_set
.mg_node
),
637 .task_iters
= LIST_HEAD_INIT(init_css_set
.task_iters
),
640 static int css_set_count
= 1; /* 1 for init_css_set */
643 * css_set_populated - does a css_set contain any tasks?
644 * @cset: target css_set
646 static bool css_set_populated(struct css_set
*cset
)
648 lockdep_assert_held(&css_set_lock
);
650 return !list_empty(&cset
->tasks
) || !list_empty(&cset
->mg_tasks
);
654 * cgroup_update_populated - updated populated count of a cgroup
655 * @cgrp: the target cgroup
656 * @populated: inc or dec populated count
658 * One of the css_sets associated with @cgrp is either getting its first
659 * task or losing the last. Update @cgrp->populated_cnt accordingly. The
660 * count is propagated towards root so that a given cgroup's populated_cnt
661 * is zero iff the cgroup and all its descendants don't contain any tasks.
663 * @cgrp's interface file "cgroup.populated" is zero if
664 * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
665 * changes from or to zero, userland is notified that the content of the
666 * interface file has changed. This can be used to detect when @cgrp and
667 * its descendants become populated or empty.
669 static void cgroup_update_populated(struct cgroup
*cgrp
, bool populated
)
671 lockdep_assert_held(&css_set_lock
);
677 trigger
= !cgrp
->populated_cnt
++;
679 trigger
= !--cgrp
->populated_cnt
;
684 check_for_release(cgrp
);
685 cgroup_file_notify(&cgrp
->events_file
);
687 cgrp
= cgroup_parent(cgrp
);
692 * css_set_update_populated - update populated state of a css_set
693 * @cset: target css_set
694 * @populated: whether @cset is populated or depopulated
696 * @cset is either getting the first task or losing the last. Update the
697 * ->populated_cnt of all associated cgroups accordingly.
699 static void css_set_update_populated(struct css_set
*cset
, bool populated
)
701 struct cgrp_cset_link
*link
;
703 lockdep_assert_held(&css_set_lock
);
705 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
)
706 cgroup_update_populated(link
->cgrp
, populated
);
710 * css_set_move_task - move a task from one css_set to another
711 * @task: task being moved
712 * @from_cset: css_set @task currently belongs to (may be NULL)
713 * @to_cset: new css_set @task is being moved to (may be NULL)
714 * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
716 * Move @task from @from_cset to @to_cset. If @task didn't belong to any
717 * css_set, @from_cset can be NULL. If @task is being disassociated
718 * instead of moved, @to_cset can be NULL.
720 * This function automatically handles populated_cnt updates and
721 * css_task_iter adjustments but the caller is responsible for managing
722 * @from_cset and @to_cset's reference counts.
724 static void css_set_move_task(struct task_struct
*task
,
725 struct css_set
*from_cset
, struct css_set
*to_cset
,
728 lockdep_assert_held(&css_set_lock
);
730 if (to_cset
&& !css_set_populated(to_cset
))
731 css_set_update_populated(to_cset
, true);
734 struct css_task_iter
*it
, *pos
;
736 WARN_ON_ONCE(list_empty(&task
->cg_list
));
739 * @task is leaving, advance task iterators which are
740 * pointing to it so that they can resume at the next
741 * position. Advancing an iterator might remove it from
742 * the list, use safe walk. See css_task_iter_advance*()
745 list_for_each_entry_safe(it
, pos
, &from_cset
->task_iters
,
747 if (it
->task_pos
== &task
->cg_list
)
748 css_task_iter_advance(it
);
750 list_del_init(&task
->cg_list
);
751 if (!css_set_populated(from_cset
))
752 css_set_update_populated(from_cset
, false);
754 WARN_ON_ONCE(!list_empty(&task
->cg_list
));
759 * We are synchronized through cgroup_threadgroup_rwsem
760 * against PF_EXITING setting such that we can't race
761 * against cgroup_exit() changing the css_set to
762 * init_css_set and dropping the old one.
764 WARN_ON_ONCE(task
->flags
& PF_EXITING
);
766 rcu_assign_pointer(task
->cgroups
, to_cset
);
767 list_add_tail(&task
->cg_list
, use_mg_tasks
? &to_cset
->mg_tasks
:
773 * hash table for cgroup groups. This improves the performance to find
774 * an existing css_set. This hash doesn't (currently) take into
775 * account cgroups in empty hierarchies.
777 #define CSS_SET_HASH_BITS 7
778 static DEFINE_HASHTABLE(css_set_table
, CSS_SET_HASH_BITS
);
780 static unsigned long css_set_hash(struct cgroup_subsys_state
*css
[])
782 unsigned long key
= 0UL;
783 struct cgroup_subsys
*ss
;
786 for_each_subsys(ss
, i
)
787 key
+= (unsigned long)css
[i
];
788 key
= (key
>> 16) ^ key
;
793 static void put_css_set_locked(struct css_set
*cset
)
795 struct cgrp_cset_link
*link
, *tmp_link
;
796 struct cgroup_subsys
*ss
;
799 lockdep_assert_held(&css_set_lock
);
801 if (!atomic_dec_and_test(&cset
->refcount
))
804 /* This css_set is dead. unlink it and release cgroup and css refs */
805 for_each_subsys(ss
, ssid
) {
806 list_del(&cset
->e_cset_node
[ssid
]);
807 css_put(cset
->subsys
[ssid
]);
809 hash_del(&cset
->hlist
);
812 list_for_each_entry_safe(link
, tmp_link
, &cset
->cgrp_links
, cgrp_link
) {
813 list_del(&link
->cset_link
);
814 list_del(&link
->cgrp_link
);
815 if (cgroup_parent(link
->cgrp
))
816 cgroup_put(link
->cgrp
);
820 kfree_rcu(cset
, rcu_head
);
823 static void put_css_set(struct css_set
*cset
)
826 * Ensure that the refcount doesn't hit zero while any readers
827 * can see it. Similar to atomic_dec_and_lock(), but for an
830 if (atomic_add_unless(&cset
->refcount
, -1, 1))
833 spin_lock_bh(&css_set_lock
);
834 put_css_set_locked(cset
);
835 spin_unlock_bh(&css_set_lock
);
839 * refcounted get/put for css_set objects
841 static inline void get_css_set(struct css_set
*cset
)
843 atomic_inc(&cset
->refcount
);
847 * compare_css_sets - helper function for find_existing_css_set().
848 * @cset: candidate css_set being tested
849 * @old_cset: existing css_set for a task
850 * @new_cgrp: cgroup that's being entered by the task
851 * @template: desired set of css pointers in css_set (pre-calculated)
853 * Returns true if "cset" matches "old_cset" except for the hierarchy
854 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
856 static bool compare_css_sets(struct css_set
*cset
,
857 struct css_set
*old_cset
,
858 struct cgroup
*new_cgrp
,
859 struct cgroup_subsys_state
*template[])
861 struct list_head
*l1
, *l2
;
864 * On the default hierarchy, there can be csets which are
865 * associated with the same set of cgroups but different csses.
866 * Let's first ensure that csses match.
868 if (memcmp(template, cset
->subsys
, sizeof(cset
->subsys
)))
872 * Compare cgroup pointers in order to distinguish between
873 * different cgroups in hierarchies. As different cgroups may
874 * share the same effective css, this comparison is always
877 l1
= &cset
->cgrp_links
;
878 l2
= &old_cset
->cgrp_links
;
880 struct cgrp_cset_link
*link1
, *link2
;
881 struct cgroup
*cgrp1
, *cgrp2
;
885 /* See if we reached the end - both lists are equal length. */
886 if (l1
== &cset
->cgrp_links
) {
887 BUG_ON(l2
!= &old_cset
->cgrp_links
);
890 BUG_ON(l2
== &old_cset
->cgrp_links
);
892 /* Locate the cgroups associated with these links. */
893 link1
= list_entry(l1
, struct cgrp_cset_link
, cgrp_link
);
894 link2
= list_entry(l2
, struct cgrp_cset_link
, cgrp_link
);
897 /* Hierarchies should be linked in the same order. */
898 BUG_ON(cgrp1
->root
!= cgrp2
->root
);
901 * If this hierarchy is the hierarchy of the cgroup
902 * that's changing, then we need to check that this
903 * css_set points to the new cgroup; if it's any other
904 * hierarchy, then this css_set should point to the
905 * same cgroup as the old css_set.
907 if (cgrp1
->root
== new_cgrp
->root
) {
908 if (cgrp1
!= new_cgrp
)
919 * find_existing_css_set - init css array and find the matching css_set
920 * @old_cset: the css_set that we're using before the cgroup transition
921 * @cgrp: the cgroup that we're moving into
922 * @template: out param for the new set of csses, should be clear on entry
924 static struct css_set
*find_existing_css_set(struct css_set
*old_cset
,
926 struct cgroup_subsys_state
*template[])
928 struct cgroup_root
*root
= cgrp
->root
;
929 struct cgroup_subsys
*ss
;
930 struct css_set
*cset
;
935 * Build the set of subsystem state objects that we want to see in the
936 * new css_set. while subsystems can change globally, the entries here
937 * won't change, so no need for locking.
939 for_each_subsys(ss
, i
) {
940 if (root
->subsys_mask
& (1UL << i
)) {
942 * @ss is in this hierarchy, so we want the
943 * effective css from @cgrp.
945 template[i
] = cgroup_e_css(cgrp
, ss
);
948 * @ss is not in this hierarchy, so we don't want
951 template[i
] = old_cset
->subsys
[i
];
955 key
= css_set_hash(template);
956 hash_for_each_possible(css_set_table
, cset
, hlist
, key
) {
957 if (!compare_css_sets(cset
, old_cset
, cgrp
, template))
960 /* This css_set matches what we need */
964 /* No existing cgroup group matched */
968 static void free_cgrp_cset_links(struct list_head
*links_to_free
)
970 struct cgrp_cset_link
*link
, *tmp_link
;
972 list_for_each_entry_safe(link
, tmp_link
, links_to_free
, cset_link
) {
973 list_del(&link
->cset_link
);
979 * allocate_cgrp_cset_links - allocate cgrp_cset_links
980 * @count: the number of links to allocate
981 * @tmp_links: list_head the allocated links are put on
983 * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
984 * through ->cset_link. Returns 0 on success or -errno.
986 static int allocate_cgrp_cset_links(int count
, struct list_head
*tmp_links
)
988 struct cgrp_cset_link
*link
;
991 INIT_LIST_HEAD(tmp_links
);
993 for (i
= 0; i
< count
; i
++) {
994 link
= kzalloc(sizeof(*link
), GFP_KERNEL
);
996 free_cgrp_cset_links(tmp_links
);
999 list_add(&link
->cset_link
, tmp_links
);
1005 * link_css_set - a helper function to link a css_set to a cgroup
1006 * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
1007 * @cset: the css_set to be linked
1008 * @cgrp: the destination cgroup
1010 static void link_css_set(struct list_head
*tmp_links
, struct css_set
*cset
,
1011 struct cgroup
*cgrp
)
1013 struct cgrp_cset_link
*link
;
1015 BUG_ON(list_empty(tmp_links
));
1017 if (cgroup_on_dfl(cgrp
))
1018 cset
->dfl_cgrp
= cgrp
;
1020 link
= list_first_entry(tmp_links
, struct cgrp_cset_link
, cset_link
);
1025 * Always add links to the tail of the lists so that the lists are
1026 * in choronological order.
1028 list_move_tail(&link
->cset_link
, &cgrp
->cset_links
);
1029 list_add_tail(&link
->cgrp_link
, &cset
->cgrp_links
);
1031 if (cgroup_parent(cgrp
))
1036 * find_css_set - return a new css_set with one cgroup updated
1037 * @old_cset: the baseline css_set
1038 * @cgrp: the cgroup to be updated
1040 * Return a new css_set that's equivalent to @old_cset, but with @cgrp
1041 * substituted into the appropriate hierarchy.
1043 static struct css_set
*find_css_set(struct css_set
*old_cset
,
1044 struct cgroup
*cgrp
)
1046 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
] = { };
1047 struct css_set
*cset
;
1048 struct list_head tmp_links
;
1049 struct cgrp_cset_link
*link
;
1050 struct cgroup_subsys
*ss
;
1054 lockdep_assert_held(&cgroup_mutex
);
1056 /* First see if we already have a cgroup group that matches
1057 * the desired set */
1058 spin_lock_bh(&css_set_lock
);
1059 cset
= find_existing_css_set(old_cset
, cgrp
, template);
1062 spin_unlock_bh(&css_set_lock
);
1067 cset
= kzalloc(sizeof(*cset
), GFP_KERNEL
);
1071 /* Allocate all the cgrp_cset_link objects that we'll need */
1072 if (allocate_cgrp_cset_links(cgroup_root_count
, &tmp_links
) < 0) {
1077 atomic_set(&cset
->refcount
, 1);
1078 INIT_LIST_HEAD(&cset
->cgrp_links
);
1079 INIT_LIST_HEAD(&cset
->tasks
);
1080 INIT_LIST_HEAD(&cset
->mg_tasks
);
1081 INIT_LIST_HEAD(&cset
->mg_preload_node
);
1082 INIT_LIST_HEAD(&cset
->mg_node
);
1083 INIT_LIST_HEAD(&cset
->task_iters
);
1084 INIT_HLIST_NODE(&cset
->hlist
);
1086 /* Copy the set of subsystem state objects generated in
1087 * find_existing_css_set() */
1088 memcpy(cset
->subsys
, template, sizeof(cset
->subsys
));
1090 spin_lock_bh(&css_set_lock
);
1091 /* Add reference counts and links from the new css_set. */
1092 list_for_each_entry(link
, &old_cset
->cgrp_links
, cgrp_link
) {
1093 struct cgroup
*c
= link
->cgrp
;
1095 if (c
->root
== cgrp
->root
)
1097 link_css_set(&tmp_links
, cset
, c
);
1100 BUG_ON(!list_empty(&tmp_links
));
1104 /* Add @cset to the hash table */
1105 key
= css_set_hash(cset
->subsys
);
1106 hash_add(css_set_table
, &cset
->hlist
, key
);
1108 for_each_subsys(ss
, ssid
) {
1109 struct cgroup_subsys_state
*css
= cset
->subsys
[ssid
];
1111 list_add_tail(&cset
->e_cset_node
[ssid
],
1112 &css
->cgroup
->e_csets
[ssid
]);
1116 spin_unlock_bh(&css_set_lock
);
1121 static struct cgroup_root
*cgroup_root_from_kf(struct kernfs_root
*kf_root
)
1123 struct cgroup
*root_cgrp
= kf_root
->kn
->priv
;
1125 return root_cgrp
->root
;
1128 static int cgroup_init_root_id(struct cgroup_root
*root
)
1132 lockdep_assert_held(&cgroup_mutex
);
1134 id
= idr_alloc_cyclic(&cgroup_hierarchy_idr
, root
, 0, 0, GFP_KERNEL
);
1138 root
->hierarchy_id
= id
;
1142 static void cgroup_exit_root_id(struct cgroup_root
*root
)
1144 lockdep_assert_held(&cgroup_mutex
);
1146 if (root
->hierarchy_id
) {
1147 idr_remove(&cgroup_hierarchy_idr
, root
->hierarchy_id
);
1148 root
->hierarchy_id
= 0;
1152 static void cgroup_free_root(struct cgroup_root
*root
)
1155 /* hierarchy ID should already have been released */
1156 WARN_ON_ONCE(root
->hierarchy_id
);
1158 idr_destroy(&root
->cgroup_idr
);
1163 static void cgroup_destroy_root(struct cgroup_root
*root
)
1165 struct cgroup
*cgrp
= &root
->cgrp
;
1166 struct cgrp_cset_link
*link
, *tmp_link
;
1168 cgroup_lock_and_drain_offline(&cgrp_dfl_root
.cgrp
);
1170 BUG_ON(atomic_read(&root
->nr_cgrps
));
1171 BUG_ON(!list_empty(&cgrp
->self
.children
));
1173 /* Rebind all subsystems back to the default hierarchy */
1174 WARN_ON(rebind_subsystems(&cgrp_dfl_root
, root
->subsys_mask
));
1177 * Release all the links from cset_links to this hierarchy's
1180 spin_lock_bh(&css_set_lock
);
1182 list_for_each_entry_safe(link
, tmp_link
, &cgrp
->cset_links
, cset_link
) {
1183 list_del(&link
->cset_link
);
1184 list_del(&link
->cgrp_link
);
1188 spin_unlock_bh(&css_set_lock
);
1190 if (!list_empty(&root
->root_list
)) {
1191 list_del(&root
->root_list
);
1192 cgroup_root_count
--;
1195 cgroup_exit_root_id(root
);
1197 mutex_unlock(&cgroup_mutex
);
1199 kernfs_destroy_root(root
->kf_root
);
1200 cgroup_free_root(root
);
1203 /* look up cgroup associated with given css_set on the specified hierarchy */
1204 static struct cgroup
*cset_cgroup_from_root(struct css_set
*cset
,
1205 struct cgroup_root
*root
)
1207 struct cgroup
*res
= NULL
;
1209 lockdep_assert_held(&cgroup_mutex
);
1210 lockdep_assert_held(&css_set_lock
);
1212 if (cset
== &init_css_set
) {
1215 struct cgrp_cset_link
*link
;
1217 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
1218 struct cgroup
*c
= link
->cgrp
;
1220 if (c
->root
== root
) {
1232 * Return the cgroup for "task" from the given hierarchy. Must be
1233 * called with cgroup_mutex and css_set_lock held.
1235 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
1236 struct cgroup_root
*root
)
1239 * No need to lock the task - since we hold cgroup_mutex the
1240 * task can't change groups, so the only thing that can happen
1241 * is that it exits and its css is set back to init_css_set.
1243 return cset_cgroup_from_root(task_css_set(task
), root
);
1247 * A task must hold cgroup_mutex to modify cgroups.
1249 * Any task can increment and decrement the count field without lock.
1250 * So in general, code holding cgroup_mutex can't rely on the count
1251 * field not changing. However, if the count goes to zero, then only
1252 * cgroup_attach_task() can increment it again. Because a count of zero
1253 * means that no tasks are currently attached, therefore there is no
1254 * way a task attached to that cgroup can fork (the other way to
1255 * increment the count). So code holding cgroup_mutex can safely
1256 * assume that if the count is zero, it will stay zero. Similarly, if
1257 * a task holds cgroup_mutex on a cgroup with zero count, it
1258 * knows that the cgroup won't be removed, as cgroup_rmdir()
1261 * A cgroup can only be deleted if both its 'count' of using tasks
1262 * is zero, and its list of 'children' cgroups is empty. Since all
1263 * tasks in the system use _some_ cgroup, and since there is always at
1264 * least one task in the system (init, pid == 1), therefore, root cgroup
1265 * always has either children cgroups and/or using tasks. So we don't
1266 * need a special hack to ensure that root cgroup cannot be deleted.
1268 * P.S. One more locking exception. RCU is used to guard the
1269 * update of a tasks cgroup pointer by cgroup_attach_task()
1272 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
;
1273 static const struct file_operations proc_cgroupstats_operations
;
1275 static char *cgroup_file_name(struct cgroup
*cgrp
, const struct cftype
*cft
,
1278 struct cgroup_subsys
*ss
= cft
->ss
;
1280 if (cft
->ss
&& !(cft
->flags
& CFTYPE_NO_PREFIX
) &&
1281 !(cgrp
->root
->flags
& CGRP_ROOT_NOPREFIX
))
1282 snprintf(buf
, CGROUP_FILE_NAME_MAX
, "%s.%s",
1283 cgroup_on_dfl(cgrp
) ? ss
->name
: ss
->legacy_name
,
1286 strncpy(buf
, cft
->name
, CGROUP_FILE_NAME_MAX
);
1291 * cgroup_file_mode - deduce file mode of a control file
1292 * @cft: the control file in question
1294 * S_IRUGO for read, S_IWUSR for write.
1296 static umode_t
cgroup_file_mode(const struct cftype
*cft
)
1300 if (cft
->read_u64
|| cft
->read_s64
|| cft
->seq_show
)
1303 if (cft
->write_u64
|| cft
->write_s64
|| cft
->write
) {
1304 if (cft
->flags
& CFTYPE_WORLD_WRITABLE
)
1314 * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
1315 * @subtree_control: the new subtree_control mask to consider
1316 * @this_ss_mask: available subsystems
1318 * On the default hierarchy, a subsystem may request other subsystems to be
1319 * enabled together through its ->depends_on mask. In such cases, more
1320 * subsystems than specified in "cgroup.subtree_control" may be enabled.
1322 * This function calculates which subsystems need to be enabled if
1323 * @subtree_control is to be applied while restricted to @this_ss_mask.
1325 static u16
cgroup_calc_subtree_ss_mask(u16 subtree_control
, u16 this_ss_mask
)
1327 u16 cur_ss_mask
= subtree_control
;
1328 struct cgroup_subsys
*ss
;
1331 lockdep_assert_held(&cgroup_mutex
);
1333 cur_ss_mask
|= cgrp_dfl_implicit_ss_mask
;
1336 u16 new_ss_mask
= cur_ss_mask
;
1338 do_each_subsys_mask(ss
, ssid
, cur_ss_mask
) {
1339 new_ss_mask
|= ss
->depends_on
;
1340 } while_each_subsys_mask();
1343 * Mask out subsystems which aren't available. This can
1344 * happen only if some depended-upon subsystems were bound
1345 * to non-default hierarchies.
1347 new_ss_mask
&= this_ss_mask
;
1349 if (new_ss_mask
== cur_ss_mask
)
1351 cur_ss_mask
= new_ss_mask
;
1358 * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
1359 * @kn: the kernfs_node being serviced
1361 * This helper undoes cgroup_kn_lock_live() and should be invoked before
1362 * the method finishes if locking succeeded. Note that once this function
1363 * returns the cgroup returned by cgroup_kn_lock_live() may become
1364 * inaccessible any time. If the caller intends to continue to access the
1365 * cgroup, it should pin it before invoking this function.
1367 static void cgroup_kn_unlock(struct kernfs_node
*kn
)
1369 struct cgroup
*cgrp
;
1371 if (kernfs_type(kn
) == KERNFS_DIR
)
1374 cgrp
= kn
->parent
->priv
;
1376 mutex_unlock(&cgroup_mutex
);
1378 kernfs_unbreak_active_protection(kn
);
1383 * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
1384 * @kn: the kernfs_node being serviced
1385 * @drain_offline: perform offline draining on the cgroup
1387 * This helper is to be used by a cgroup kernfs method currently servicing
1388 * @kn. It breaks the active protection, performs cgroup locking and
1389 * verifies that the associated cgroup is alive. Returns the cgroup if
1390 * alive; otherwise, %NULL. A successful return should be undone by a
1391 * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
1392 * cgroup is drained of offlining csses before return.
1394 * Any cgroup kernfs method implementation which requires locking the
1395 * associated cgroup should use this helper. It avoids nesting cgroup
1396 * locking under kernfs active protection and allows all kernfs operations
1397 * including self-removal.
1399 static struct cgroup
*cgroup_kn_lock_live(struct kernfs_node
*kn
,
1402 struct cgroup
*cgrp
;
1404 if (kernfs_type(kn
) == KERNFS_DIR
)
1407 cgrp
= kn
->parent
->priv
;
1410 * We're gonna grab cgroup_mutex which nests outside kernfs
1411 * active_ref. cgroup liveliness check alone provides enough
1412 * protection against removal. Ensure @cgrp stays accessible and
1413 * break the active_ref protection.
1415 if (!cgroup_tryget(cgrp
))
1417 kernfs_break_active_protection(kn
);
1420 cgroup_lock_and_drain_offline(cgrp
);
1422 mutex_lock(&cgroup_mutex
);
1424 if (!cgroup_is_dead(cgrp
))
1427 cgroup_kn_unlock(kn
);
1431 static void cgroup_rm_file(struct cgroup
*cgrp
, const struct cftype
*cft
)
1433 char name
[CGROUP_FILE_NAME_MAX
];
1435 lockdep_assert_held(&cgroup_mutex
);
1437 if (cft
->file_offset
) {
1438 struct cgroup_subsys_state
*css
= cgroup_css(cgrp
, cft
->ss
);
1439 struct cgroup_file
*cfile
= (void *)css
+ cft
->file_offset
;
1441 spin_lock_irq(&cgroup_file_kn_lock
);
1443 spin_unlock_irq(&cgroup_file_kn_lock
);
1446 kernfs_remove_by_name(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
));
1450 * css_clear_dir - remove subsys files in a cgroup directory
1453 static void css_clear_dir(struct cgroup_subsys_state
*css
)
1455 struct cgroup
*cgrp
= css
->cgroup
;
1456 struct cftype
*cfts
;
1458 if (!(css
->flags
& CSS_VISIBLE
))
1461 css
->flags
&= ~CSS_VISIBLE
;
1463 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
)
1464 cgroup_addrm_files(css
, cgrp
, cfts
, false);
1468 * css_populate_dir - create subsys files in a cgroup directory
1471 * On failure, no file is added.
1473 static int css_populate_dir(struct cgroup_subsys_state
*css
)
1475 struct cgroup
*cgrp
= css
->cgroup
;
1476 struct cftype
*cfts
, *failed_cfts
;
1479 if ((css
->flags
& CSS_VISIBLE
) || !cgrp
->kn
)
1483 if (cgroup_on_dfl(cgrp
))
1484 cfts
= cgroup_dfl_base_files
;
1486 cfts
= cgroup_legacy_base_files
;
1488 return cgroup_addrm_files(&cgrp
->self
, cgrp
, cfts
, true);
1491 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
) {
1492 ret
= cgroup_addrm_files(css
, cgrp
, cfts
, true);
1499 css
->flags
|= CSS_VISIBLE
;
1503 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
) {
1504 if (cfts
== failed_cfts
)
1506 cgroup_addrm_files(css
, cgrp
, cfts
, false);
1511 static int rebind_subsystems(struct cgroup_root
*dst_root
, u16 ss_mask
)
1513 struct cgroup
*dcgrp
= &dst_root
->cgrp
;
1514 struct cgroup_subsys
*ss
;
1517 lockdep_assert_held(&cgroup_mutex
);
1519 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
1521 * If @ss has non-root csses attached to it, can't move.
1522 * If @ss is an implicit controller, it is exempt from this
1523 * rule and can be stolen.
1525 if (css_next_child(NULL
, cgroup_css(&ss
->root
->cgrp
, ss
)) &&
1526 !ss
->implicit_on_dfl
)
1529 /* can't move between two non-dummy roots either */
1530 if (ss
->root
!= &cgrp_dfl_root
&& dst_root
!= &cgrp_dfl_root
)
1532 } while_each_subsys_mask();
1534 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
1535 struct cgroup_root
*src_root
= ss
->root
;
1536 struct cgroup
*scgrp
= &src_root
->cgrp
;
1537 struct cgroup_subsys_state
*css
= cgroup_css(scgrp
, ss
);
1538 struct css_set
*cset
;
1540 WARN_ON(!css
|| cgroup_css(dcgrp
, ss
));
1542 /* disable from the source */
1543 src_root
->subsys_mask
&= ~(1 << ssid
);
1544 WARN_ON(cgroup_apply_control(scgrp
));
1545 cgroup_finalize_control(scgrp
, 0);
1548 RCU_INIT_POINTER(scgrp
->subsys
[ssid
], NULL
);
1549 rcu_assign_pointer(dcgrp
->subsys
[ssid
], css
);
1550 ss
->root
= dst_root
;
1551 css
->cgroup
= dcgrp
;
1553 spin_lock_bh(&css_set_lock
);
1554 hash_for_each(css_set_table
, i
, cset
, hlist
)
1555 list_move_tail(&cset
->e_cset_node
[ss
->id
],
1556 &dcgrp
->e_csets
[ss
->id
]);
1557 spin_unlock_bh(&css_set_lock
);
1559 /* default hierarchy doesn't enable controllers by default */
1560 dst_root
->subsys_mask
|= 1 << ssid
;
1561 if (dst_root
== &cgrp_dfl_root
) {
1562 static_branch_enable(cgroup_subsys_on_dfl_key
[ssid
]);
1564 dcgrp
->subtree_control
|= 1 << ssid
;
1565 static_branch_disable(cgroup_subsys_on_dfl_key
[ssid
]);
1568 ret
= cgroup_apply_control(dcgrp
);
1570 pr_warn("partial failure to rebind %s controller (err=%d)\n",
1575 } while_each_subsys_mask();
1577 kernfs_activate(dcgrp
->kn
);
1581 static int cgroup_show_options(struct seq_file
*seq
,
1582 struct kernfs_root
*kf_root
)
1584 struct cgroup_root
*root
= cgroup_root_from_kf(kf_root
);
1585 struct cgroup_subsys
*ss
;
1588 if (root
!= &cgrp_dfl_root
)
1589 for_each_subsys(ss
, ssid
)
1590 if (root
->subsys_mask
& (1 << ssid
))
1591 seq_show_option(seq
, ss
->legacy_name
, NULL
);
1592 if (root
->flags
& CGRP_ROOT_NOPREFIX
)
1593 seq_puts(seq
, ",noprefix");
1594 if (root
->flags
& CGRP_ROOT_XATTR
)
1595 seq_puts(seq
, ",xattr");
1597 spin_lock(&release_agent_path_lock
);
1598 if (strlen(root
->release_agent_path
))
1599 seq_show_option(seq
, "release_agent",
1600 root
->release_agent_path
);
1601 spin_unlock(&release_agent_path_lock
);
1603 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->cgrp
.flags
))
1604 seq_puts(seq
, ",clone_children");
1605 if (strlen(root
->name
))
1606 seq_show_option(seq
, "name", root
->name
);
1610 struct cgroup_sb_opts
{
1613 char *release_agent
;
1614 bool cpuset_clone_children
;
1616 /* User explicitly requested empty subsystem */
1620 static int parse_cgroupfs_options(char *data
, struct cgroup_sb_opts
*opts
)
1622 char *token
, *o
= data
;
1623 bool all_ss
= false, one_ss
= false;
1625 struct cgroup_subsys
*ss
;
1629 #ifdef CONFIG_CPUSETS
1630 mask
= ~((u16
)1 << cpuset_cgrp_id
);
1633 memset(opts
, 0, sizeof(*opts
));
1635 while ((token
= strsep(&o
, ",")) != NULL
) {
1640 if (!strcmp(token
, "none")) {
1641 /* Explicitly have no subsystems */
1645 if (!strcmp(token
, "all")) {
1646 /* Mutually exclusive option 'all' + subsystem name */
1652 if (!strcmp(token
, "noprefix")) {
1653 opts
->flags
|= CGRP_ROOT_NOPREFIX
;
1656 if (!strcmp(token
, "clone_children")) {
1657 opts
->cpuset_clone_children
= true;
1660 if (!strcmp(token
, "xattr")) {
1661 opts
->flags
|= CGRP_ROOT_XATTR
;
1664 if (!strncmp(token
, "release_agent=", 14)) {
1665 /* Specifying two release agents is forbidden */
1666 if (opts
->release_agent
)
1668 opts
->release_agent
=
1669 kstrndup(token
+ 14, PATH_MAX
- 1, GFP_KERNEL
);
1670 if (!opts
->release_agent
)
1674 if (!strncmp(token
, "name=", 5)) {
1675 const char *name
= token
+ 5;
1676 /* Can't specify an empty name */
1679 /* Must match [\w.-]+ */
1680 for (i
= 0; i
< strlen(name
); i
++) {
1684 if ((c
== '.') || (c
== '-') || (c
== '_'))
1688 /* Specifying two names is forbidden */
1691 opts
->name
= kstrndup(name
,
1692 MAX_CGROUP_ROOT_NAMELEN
- 1,
1700 for_each_subsys(ss
, i
) {
1701 if (strcmp(token
, ss
->legacy_name
))
1703 if (!cgroup_ssid_enabled(i
))
1705 if (cgroup_ssid_no_v1(i
))
1708 /* Mutually exclusive option 'all' + subsystem name */
1711 opts
->subsys_mask
|= (1 << i
);
1716 if (i
== CGROUP_SUBSYS_COUNT
)
1721 * If the 'all' option was specified select all the subsystems,
1722 * otherwise if 'none', 'name=' and a subsystem name options were
1723 * not specified, let's default to 'all'
1725 if (all_ss
|| (!one_ss
&& !opts
->none
&& !opts
->name
))
1726 for_each_subsys(ss
, i
)
1727 if (cgroup_ssid_enabled(i
) && !cgroup_ssid_no_v1(i
))
1728 opts
->subsys_mask
|= (1 << i
);
1731 * We either have to specify by name or by subsystems. (So all
1732 * empty hierarchies must have a name).
1734 if (!opts
->subsys_mask
&& !opts
->name
)
1738 * Option noprefix was introduced just for backward compatibility
1739 * with the old cpuset, so we allow noprefix only if mounting just
1740 * the cpuset subsystem.
1742 if ((opts
->flags
& CGRP_ROOT_NOPREFIX
) && (opts
->subsys_mask
& mask
))
1745 /* Can't specify "none" and some subsystems */
1746 if (opts
->subsys_mask
&& opts
->none
)
1752 static int cgroup_remount(struct kernfs_root
*kf_root
, int *flags
, char *data
)
1755 struct cgroup_root
*root
= cgroup_root_from_kf(kf_root
);
1756 struct cgroup_sb_opts opts
;
1757 u16 added_mask
, removed_mask
;
1759 if (root
== &cgrp_dfl_root
) {
1760 pr_err("remount is not allowed\n");
1764 cgroup_lock_and_drain_offline(&cgrp_dfl_root
.cgrp
);
1766 /* See what subsystems are wanted */
1767 ret
= parse_cgroupfs_options(data
, &opts
);
1771 if (opts
.subsys_mask
!= root
->subsys_mask
|| opts
.release_agent
)
1772 pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
1773 task_tgid_nr(current
), current
->comm
);
1775 added_mask
= opts
.subsys_mask
& ~root
->subsys_mask
;
1776 removed_mask
= root
->subsys_mask
& ~opts
.subsys_mask
;
1778 /* Don't allow flags or name to change at remount */
1779 if ((opts
.flags
^ root
->flags
) ||
1780 (opts
.name
&& strcmp(opts
.name
, root
->name
))) {
1781 pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
1782 opts
.flags
, opts
.name
?: "", root
->flags
, root
->name
);
1787 /* remounting is not allowed for populated hierarchies */
1788 if (!list_empty(&root
->cgrp
.self
.children
)) {
1793 ret
= rebind_subsystems(root
, added_mask
);
1797 WARN_ON(rebind_subsystems(&cgrp_dfl_root
, removed_mask
));
1799 if (opts
.release_agent
) {
1800 spin_lock(&release_agent_path_lock
);
1801 strcpy(root
->release_agent_path
, opts
.release_agent
);
1802 spin_unlock(&release_agent_path_lock
);
1805 kfree(opts
.release_agent
);
1807 mutex_unlock(&cgroup_mutex
);
1812 * To reduce the fork() overhead for systems that are not actually using
1813 * their cgroups capability, we don't maintain the lists running through
1814 * each css_set to its tasks until we see the list actually used - in other
1815 * words after the first mount.
1817 static bool use_task_css_set_links __read_mostly
;
1819 static void cgroup_enable_task_cg_lists(void)
1821 struct task_struct
*p
, *g
;
1823 spin_lock_bh(&css_set_lock
);
1825 if (use_task_css_set_links
)
1828 use_task_css_set_links
= true;
1831 * We need tasklist_lock because RCU is not safe against
1832 * while_each_thread(). Besides, a forking task that has passed
1833 * cgroup_post_fork() without seeing use_task_css_set_links = 1
1834 * is not guaranteed to have its child immediately visible in the
1835 * tasklist if we walk through it with RCU.
1837 read_lock(&tasklist_lock
);
1838 do_each_thread(g
, p
) {
1839 WARN_ON_ONCE(!list_empty(&p
->cg_list
) ||
1840 task_css_set(p
) != &init_css_set
);
1843 * We should check if the process is exiting, otherwise
1844 * it will race with cgroup_exit() in that the list
1845 * entry won't be deleted though the process has exited.
1846 * Do it while holding siglock so that we don't end up
1847 * racing against cgroup_exit().
1849 spin_lock_irq(&p
->sighand
->siglock
);
1850 if (!(p
->flags
& PF_EXITING
)) {
1851 struct css_set
*cset
= task_css_set(p
);
1853 if (!css_set_populated(cset
))
1854 css_set_update_populated(cset
, true);
1855 list_add_tail(&p
->cg_list
, &cset
->tasks
);
1858 spin_unlock_irq(&p
->sighand
->siglock
);
1859 } while_each_thread(g
, p
);
1860 read_unlock(&tasklist_lock
);
1862 spin_unlock_bh(&css_set_lock
);
1865 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1867 struct cgroup_subsys
*ss
;
1870 INIT_LIST_HEAD(&cgrp
->self
.sibling
);
1871 INIT_LIST_HEAD(&cgrp
->self
.children
);
1872 INIT_LIST_HEAD(&cgrp
->cset_links
);
1873 INIT_LIST_HEAD(&cgrp
->pidlists
);
1874 mutex_init(&cgrp
->pidlist_mutex
);
1875 cgrp
->self
.cgroup
= cgrp
;
1876 cgrp
->self
.flags
|= CSS_ONLINE
;
1878 for_each_subsys(ss
, ssid
)
1879 INIT_LIST_HEAD(&cgrp
->e_csets
[ssid
]);
1881 init_waitqueue_head(&cgrp
->offline_waitq
);
1882 INIT_WORK(&cgrp
->release_agent_work
, cgroup_release_agent
);
1885 static void init_cgroup_root(struct cgroup_root
*root
,
1886 struct cgroup_sb_opts
*opts
)
1888 struct cgroup
*cgrp
= &root
->cgrp
;
1890 INIT_LIST_HEAD(&root
->root_list
);
1891 atomic_set(&root
->nr_cgrps
, 1);
1893 init_cgroup_housekeeping(cgrp
);
1894 idr_init(&root
->cgroup_idr
);
1896 root
->flags
= opts
->flags
;
1897 if (opts
->release_agent
)
1898 strcpy(root
->release_agent_path
, opts
->release_agent
);
1900 strcpy(root
->name
, opts
->name
);
1901 if (opts
->cpuset_clone_children
)
1902 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->cgrp
.flags
);
1905 static int cgroup_setup_root(struct cgroup_root
*root
, u16 ss_mask
)
1907 LIST_HEAD(tmp_links
);
1908 struct cgroup
*root_cgrp
= &root
->cgrp
;
1909 struct css_set
*cset
;
1912 lockdep_assert_held(&cgroup_mutex
);
1914 ret
= cgroup_idr_alloc(&root
->cgroup_idr
, root_cgrp
, 1, 2, GFP_KERNEL
);
1917 root_cgrp
->id
= ret
;
1918 root_cgrp
->ancestor_ids
[0] = ret
;
1920 ret
= percpu_ref_init(&root_cgrp
->self
.refcnt
, css_release
, 0,
1926 * We're accessing css_set_count without locking css_set_lock here,
1927 * but that's OK - it can only be increased by someone holding
1928 * cgroup_lock, and that's us. Later rebinding may disable
1929 * controllers on the default hierarchy and thus create new csets,
1930 * which can't be more than the existing ones. Allocate 2x.
1932 ret
= allocate_cgrp_cset_links(2 * css_set_count
, &tmp_links
);
1936 ret
= cgroup_init_root_id(root
);
1940 root
->kf_root
= kernfs_create_root(&cgroup_kf_syscall_ops
,
1941 KERNFS_ROOT_CREATE_DEACTIVATED
,
1943 if (IS_ERR(root
->kf_root
)) {
1944 ret
= PTR_ERR(root
->kf_root
);
1947 root_cgrp
->kn
= root
->kf_root
->kn
;
1949 ret
= css_populate_dir(&root_cgrp
->self
);
1953 ret
= rebind_subsystems(root
, ss_mask
);
1958 * There must be no failure case after here, since rebinding takes
1959 * care of subsystems' refcounts, which are explicitly dropped in
1960 * the failure exit path.
1962 list_add(&root
->root_list
, &cgroup_roots
);
1963 cgroup_root_count
++;
1966 * Link the root cgroup in this hierarchy into all the css_set
1969 spin_lock_bh(&css_set_lock
);
1970 hash_for_each(css_set_table
, i
, cset
, hlist
) {
1971 link_css_set(&tmp_links
, cset
, root_cgrp
);
1972 if (css_set_populated(cset
))
1973 cgroup_update_populated(root_cgrp
, true);
1975 spin_unlock_bh(&css_set_lock
);
1977 BUG_ON(!list_empty(&root_cgrp
->self
.children
));
1978 BUG_ON(atomic_read(&root
->nr_cgrps
) != 1);
1980 kernfs_activate(root_cgrp
->kn
);
1985 kernfs_destroy_root(root
->kf_root
);
1986 root
->kf_root
= NULL
;
1988 cgroup_exit_root_id(root
);
1990 percpu_ref_exit(&root_cgrp
->self
.refcnt
);
1992 free_cgrp_cset_links(&tmp_links
);
1996 static struct dentry
*cgroup_mount(struct file_system_type
*fs_type
,
1997 int flags
, const char *unused_dev_name
,
2000 bool is_v2
= fs_type
== &cgroup2_fs_type
;
2001 struct super_block
*pinned_sb
= NULL
;
2002 struct cgroup_subsys
*ss
;
2003 struct cgroup_root
*root
;
2004 struct cgroup_sb_opts opts
;
2005 struct dentry
*dentry
;
2011 * The first time anyone tries to mount a cgroup, enable the list
2012 * linking each css_set to its tasks and fix up all existing tasks.
2014 if (!use_task_css_set_links
)
2015 cgroup_enable_task_cg_lists();
2019 pr_err("cgroup2: unknown option \"%s\"\n", (char *)data
);
2020 return ERR_PTR(-EINVAL
);
2022 cgrp_dfl_visible
= true;
2023 root
= &cgrp_dfl_root
;
2024 cgroup_get(&root
->cgrp
);
2028 cgroup_lock_and_drain_offline(&cgrp_dfl_root
.cgrp
);
2030 /* First find the desired set of subsystems */
2031 ret
= parse_cgroupfs_options(data
, &opts
);
2036 * Destruction of cgroup root is asynchronous, so subsystems may
2037 * still be dying after the previous unmount. Let's drain the
2038 * dying subsystems. We just need to ensure that the ones
2039 * unmounted previously finish dying and don't care about new ones
2040 * starting. Testing ref liveliness is good enough.
2042 for_each_subsys(ss
, i
) {
2043 if (!(opts
.subsys_mask
& (1 << i
)) ||
2044 ss
->root
== &cgrp_dfl_root
)
2047 if (!percpu_ref_tryget_live(&ss
->root
->cgrp
.self
.refcnt
)) {
2048 mutex_unlock(&cgroup_mutex
);
2050 ret
= restart_syscall();
2053 cgroup_put(&ss
->root
->cgrp
);
2056 for_each_root(root
) {
2057 bool name_match
= false;
2059 if (root
== &cgrp_dfl_root
)
2063 * If we asked for a name then it must match. Also, if
2064 * name matches but sybsys_mask doesn't, we should fail.
2065 * Remember whether name matched.
2068 if (strcmp(opts
.name
, root
->name
))
2074 * If we asked for subsystems (or explicitly for no
2075 * subsystems) then they must match.
2077 if ((opts
.subsys_mask
|| opts
.none
) &&
2078 (opts
.subsys_mask
!= root
->subsys_mask
)) {
2085 if (root
->flags
^ opts
.flags
)
2086 pr_warn("new mount options do not match the existing superblock, will be ignored\n");
2089 * We want to reuse @root whose lifetime is governed by its
2090 * ->cgrp. Let's check whether @root is alive and keep it
2091 * that way. As cgroup_kill_sb() can happen anytime, we
2092 * want to block it by pinning the sb so that @root doesn't
2093 * get killed before mount is complete.
2095 * With the sb pinned, tryget_live can reliably indicate
2096 * whether @root can be reused. If it's being killed,
2097 * drain it. We can use wait_queue for the wait but this
2098 * path is super cold. Let's just sleep a bit and retry.
2100 pinned_sb
= kernfs_pin_sb(root
->kf_root
, NULL
);
2101 if (IS_ERR(pinned_sb
) ||
2102 !percpu_ref_tryget_live(&root
->cgrp
.self
.refcnt
)) {
2103 mutex_unlock(&cgroup_mutex
);
2104 if (!IS_ERR_OR_NULL(pinned_sb
))
2105 deactivate_super(pinned_sb
);
2107 ret
= restart_syscall();
2116 * No such thing, create a new one. name= matching without subsys
2117 * specification is allowed for already existing hierarchies but we
2118 * can't create new one without subsys specification.
2120 if (!opts
.subsys_mask
&& !opts
.none
) {
2125 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
2131 init_cgroup_root(root
, &opts
);
2133 ret
= cgroup_setup_root(root
, opts
.subsys_mask
);
2135 cgroup_free_root(root
);
2138 mutex_unlock(&cgroup_mutex
);
2140 kfree(opts
.release_agent
);
2144 return ERR_PTR(ret
);
2146 dentry
= kernfs_mount(fs_type
, flags
, root
->kf_root
,
2147 is_v2
? CGROUP2_SUPER_MAGIC
: CGROUP_SUPER_MAGIC
,
2149 if (IS_ERR(dentry
) || !new_sb
)
2150 cgroup_put(&root
->cgrp
);
2153 * If @pinned_sb, we're reusing an existing root and holding an
2154 * extra ref on its sb. Mount is complete. Put the extra ref.
2158 deactivate_super(pinned_sb
);
2164 static void cgroup_kill_sb(struct super_block
*sb
)
2166 struct kernfs_root
*kf_root
= kernfs_root_from_sb(sb
);
2167 struct cgroup_root
*root
= cgroup_root_from_kf(kf_root
);
2170 * If @root doesn't have any mounts or children, start killing it.
2171 * This prevents new mounts by disabling percpu_ref_tryget_live().
2172 * cgroup_mount() may wait for @root's release.
2174 * And don't kill the default root.
2176 if (!list_empty(&root
->cgrp
.self
.children
) ||
2177 root
== &cgrp_dfl_root
)
2178 cgroup_put(&root
->cgrp
);
2180 percpu_ref_kill(&root
->cgrp
.self
.refcnt
);
2185 static struct file_system_type cgroup_fs_type
= {
2187 .mount
= cgroup_mount
,
2188 .kill_sb
= cgroup_kill_sb
,
2191 static struct file_system_type cgroup2_fs_type
= {
2193 .mount
= cgroup_mount
,
2194 .kill_sb
= cgroup_kill_sb
,
2198 * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
2199 * @task: target task
2200 * @buf: the buffer to write the path into
2201 * @buflen: the length of the buffer
2203 * Determine @task's cgroup on the first (the one with the lowest non-zero
2204 * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
2205 * function grabs cgroup_mutex and shouldn't be used inside locks used by
2206 * cgroup controller callbacks.
2208 * Return value is the same as kernfs_path().
2210 char *task_cgroup_path(struct task_struct
*task
, char *buf
, size_t buflen
)
2212 struct cgroup_root
*root
;
2213 struct cgroup
*cgrp
;
2214 int hierarchy_id
= 1;
2217 mutex_lock(&cgroup_mutex
);
2218 spin_lock_bh(&css_set_lock
);
2220 root
= idr_get_next(&cgroup_hierarchy_idr
, &hierarchy_id
);
2223 cgrp
= task_cgroup_from_root(task
, root
);
2224 path
= cgroup_path(cgrp
, buf
, buflen
);
2226 /* if no hierarchy exists, everyone is in "/" */
2227 if (strlcpy(buf
, "/", buflen
) < buflen
)
2231 spin_unlock_bh(&css_set_lock
);
2232 mutex_unlock(&cgroup_mutex
);
2235 EXPORT_SYMBOL_GPL(task_cgroup_path
);
2237 /* used to track tasks and other necessary states during migration */
2238 struct cgroup_taskset
{
2239 /* the src and dst cset list running through cset->mg_node */
2240 struct list_head src_csets
;
2241 struct list_head dst_csets
;
2243 /* the subsys currently being processed */
2247 * Fields for cgroup_taskset_*() iteration.
2249 * Before migration is committed, the target migration tasks are on
2250 * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
2251 * the csets on ->dst_csets. ->csets point to either ->src_csets
2252 * or ->dst_csets depending on whether migration is committed.
2254 * ->cur_csets and ->cur_task point to the current task position
2257 struct list_head
*csets
;
2258 struct css_set
*cur_cset
;
2259 struct task_struct
*cur_task
;
2262 #define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \
2263 .src_csets = LIST_HEAD_INIT(tset.src_csets), \
2264 .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
2265 .csets = &tset.src_csets, \
2269 * cgroup_taskset_add - try to add a migration target task to a taskset
2270 * @task: target task
2271 * @tset: target taskset
2273 * Add @task, which is a migration target, to @tset. This function becomes
2274 * noop if @task doesn't need to be migrated. @task's css_set should have
2275 * been added as a migration source and @task->cg_list will be moved from
2276 * the css_set's tasks list to mg_tasks one.
2278 static void cgroup_taskset_add(struct task_struct
*task
,
2279 struct cgroup_taskset
*tset
)
2281 struct css_set
*cset
;
2283 lockdep_assert_held(&css_set_lock
);
2285 /* @task either already exited or can't exit until the end */
2286 if (task
->flags
& PF_EXITING
)
2289 /* leave @task alone if post_fork() hasn't linked it yet */
2290 if (list_empty(&task
->cg_list
))
2293 cset
= task_css_set(task
);
2294 if (!cset
->mg_src_cgrp
)
2297 list_move_tail(&task
->cg_list
, &cset
->mg_tasks
);
2298 if (list_empty(&cset
->mg_node
))
2299 list_add_tail(&cset
->mg_node
, &tset
->src_csets
);
2300 if (list_empty(&cset
->mg_dst_cset
->mg_node
))
2301 list_move_tail(&cset
->mg_dst_cset
->mg_node
,
2306 * cgroup_taskset_first - reset taskset and return the first task
2307 * @tset: taskset of interest
2308 * @dst_cssp: output variable for the destination css
2310 * @tset iteration is initialized and the first task is returned.
2312 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
,
2313 struct cgroup_subsys_state
**dst_cssp
)
2315 tset
->cur_cset
= list_first_entry(tset
->csets
, struct css_set
, mg_node
);
2316 tset
->cur_task
= NULL
;
2318 return cgroup_taskset_next(tset
, dst_cssp
);
2322 * cgroup_taskset_next - iterate to the next task in taskset
2323 * @tset: taskset of interest
2324 * @dst_cssp: output variable for the destination css
2326 * Return the next task in @tset. Iteration must have been initialized
2327 * with cgroup_taskset_first().
2329 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
,
2330 struct cgroup_subsys_state
**dst_cssp
)
2332 struct css_set
*cset
= tset
->cur_cset
;
2333 struct task_struct
*task
= tset
->cur_task
;
2335 while (&cset
->mg_node
!= tset
->csets
) {
2337 task
= list_first_entry(&cset
->mg_tasks
,
2338 struct task_struct
, cg_list
);
2340 task
= list_next_entry(task
, cg_list
);
2342 if (&task
->cg_list
!= &cset
->mg_tasks
) {
2343 tset
->cur_cset
= cset
;
2344 tset
->cur_task
= task
;
2347 * This function may be called both before and
2348 * after cgroup_taskset_migrate(). The two cases
2349 * can be distinguished by looking at whether @cset
2350 * has its ->mg_dst_cset set.
2352 if (cset
->mg_dst_cset
)
2353 *dst_cssp
= cset
->mg_dst_cset
->subsys
[tset
->ssid
];
2355 *dst_cssp
= cset
->subsys
[tset
->ssid
];
2360 cset
= list_next_entry(cset
, mg_node
);
2368 * cgroup_taskset_migrate - migrate a taskset
2369 * @tset: taget taskset
2370 * @root: cgroup root the migration is taking place on
2372 * Migrate tasks in @tset as setup by migration preparation functions.
2373 * This function fails iff one of the ->can_attach callbacks fails and
2374 * guarantees that either all or none of the tasks in @tset are migrated.
2375 * @tset is consumed regardless of success.
2377 static int cgroup_taskset_migrate(struct cgroup_taskset
*tset
,
2378 struct cgroup_root
*root
)
2380 struct cgroup_subsys
*ss
;
2381 struct task_struct
*task
, *tmp_task
;
2382 struct css_set
*cset
, *tmp_cset
;
2383 int ssid
, failed_ssid
, ret
;
2385 /* methods shouldn't be called if no task is actually migrating */
2386 if (list_empty(&tset
->src_csets
))
2389 /* check that we can legitimately attach to the cgroup */
2390 do_each_subsys_mask(ss
, ssid
, root
->subsys_mask
) {
2391 if (ss
->can_attach
) {
2393 ret
= ss
->can_attach(tset
);
2396 goto out_cancel_attach
;
2399 } while_each_subsys_mask();
2402 * Now that we're guaranteed success, proceed to move all tasks to
2403 * the new cgroup. There are no failure cases after here, so this
2404 * is the commit point.
2406 spin_lock_bh(&css_set_lock
);
2407 list_for_each_entry(cset
, &tset
->src_csets
, mg_node
) {
2408 list_for_each_entry_safe(task
, tmp_task
, &cset
->mg_tasks
, cg_list
) {
2409 struct css_set
*from_cset
= task_css_set(task
);
2410 struct css_set
*to_cset
= cset
->mg_dst_cset
;
2412 get_css_set(to_cset
);
2413 css_set_move_task(task
, from_cset
, to_cset
, true);
2414 put_css_set_locked(from_cset
);
2417 spin_unlock_bh(&css_set_lock
);
2420 * Migration is committed, all target tasks are now on dst_csets.
2421 * Nothing is sensitive to fork() after this point. Notify
2422 * controllers that migration is complete.
2424 tset
->csets
= &tset
->dst_csets
;
2426 do_each_subsys_mask(ss
, ssid
, root
->subsys_mask
) {
2431 } while_each_subsys_mask();
2434 goto out_release_tset
;
2437 do_each_subsys_mask(ss
, ssid
, root
->subsys_mask
) {
2438 if (ssid
== failed_ssid
)
2440 if (ss
->cancel_attach
) {
2442 ss
->cancel_attach(tset
);
2444 } while_each_subsys_mask();
2446 spin_lock_bh(&css_set_lock
);
2447 list_splice_init(&tset
->dst_csets
, &tset
->src_csets
);
2448 list_for_each_entry_safe(cset
, tmp_cset
, &tset
->src_csets
, mg_node
) {
2449 list_splice_tail_init(&cset
->mg_tasks
, &cset
->tasks
);
2450 list_del_init(&cset
->mg_node
);
2452 spin_unlock_bh(&css_set_lock
);
2457 * cgroup_may_migrate_to - verify whether a cgroup can be migration destination
2458 * @dst_cgrp: destination cgroup to test
2460 * On the default hierarchy, except for the root, subtree_control must be
2461 * zero for migration destination cgroups with tasks so that child cgroups
2462 * don't compete against tasks.
2464 static bool cgroup_may_migrate_to(struct cgroup
*dst_cgrp
)
2466 return !cgroup_on_dfl(dst_cgrp
) || !cgroup_parent(dst_cgrp
) ||
2467 !dst_cgrp
->subtree_control
;
2471 * cgroup_migrate_finish - cleanup after attach
2472 * @preloaded_csets: list of preloaded css_sets
2474 * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
2475 * those functions for details.
2477 static void cgroup_migrate_finish(struct list_head
*preloaded_csets
)
2479 struct css_set
*cset
, *tmp_cset
;
2481 lockdep_assert_held(&cgroup_mutex
);
2483 spin_lock_bh(&css_set_lock
);
2484 list_for_each_entry_safe(cset
, tmp_cset
, preloaded_csets
, mg_preload_node
) {
2485 cset
->mg_src_cgrp
= NULL
;
2486 cset
->mg_dst_cgrp
= NULL
;
2487 cset
->mg_dst_cset
= NULL
;
2488 list_del_init(&cset
->mg_preload_node
);
2489 put_css_set_locked(cset
);
2491 spin_unlock_bh(&css_set_lock
);
2495 * cgroup_migrate_add_src - add a migration source css_set
2496 * @src_cset: the source css_set to add
2497 * @dst_cgrp: the destination cgroup
2498 * @preloaded_csets: list of preloaded css_sets
2500 * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
2501 * @src_cset and add it to @preloaded_csets, which should later be cleaned
2502 * up by cgroup_migrate_finish().
2504 * This function may be called without holding cgroup_threadgroup_rwsem
2505 * even if the target is a process. Threads may be created and destroyed
2506 * but as long as cgroup_mutex is not dropped, no new css_set can be put
2507 * into play and the preloaded css_sets are guaranteed to cover all
2510 static void cgroup_migrate_add_src(struct css_set
*src_cset
,
2511 struct cgroup
*dst_cgrp
,
2512 struct list_head
*preloaded_csets
)
2514 struct cgroup
*src_cgrp
;
2516 lockdep_assert_held(&cgroup_mutex
);
2517 lockdep_assert_held(&css_set_lock
);
2520 * If ->dead, @src_set is associated with one or more dead cgroups
2521 * and doesn't contain any migratable tasks. Ignore it early so
2522 * that the rest of migration path doesn't get confused by it.
2527 src_cgrp
= cset_cgroup_from_root(src_cset
, dst_cgrp
->root
);
2529 if (!list_empty(&src_cset
->mg_preload_node
))
2532 WARN_ON(src_cset
->mg_src_cgrp
);
2533 WARN_ON(src_cset
->mg_dst_cgrp
);
2534 WARN_ON(!list_empty(&src_cset
->mg_tasks
));
2535 WARN_ON(!list_empty(&src_cset
->mg_node
));
2537 src_cset
->mg_src_cgrp
= src_cgrp
;
2538 src_cset
->mg_dst_cgrp
= dst_cgrp
;
2539 get_css_set(src_cset
);
2540 list_add(&src_cset
->mg_preload_node
, preloaded_csets
);
2544 * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
2545 * @preloaded_csets: list of preloaded source css_sets
2547 * Tasks are about to be moved and all the source css_sets have been
2548 * preloaded to @preloaded_csets. This function looks up and pins all
2549 * destination css_sets, links each to its source, and append them to
2552 * This function must be called after cgroup_migrate_add_src() has been
2553 * called on each migration source css_set. After migration is performed
2554 * using cgroup_migrate(), cgroup_migrate_finish() must be called on
2557 static int cgroup_migrate_prepare_dst(struct list_head
*preloaded_csets
)
2560 struct css_set
*src_cset
, *tmp_cset
;
2562 lockdep_assert_held(&cgroup_mutex
);
2564 /* look up the dst cset for each src cset and link it to src */
2565 list_for_each_entry_safe(src_cset
, tmp_cset
, preloaded_csets
, mg_preload_node
) {
2566 struct css_set
*dst_cset
;
2568 dst_cset
= find_css_set(src_cset
, src_cset
->mg_dst_cgrp
);
2572 WARN_ON_ONCE(src_cset
->mg_dst_cset
|| dst_cset
->mg_dst_cset
);
2575 * If src cset equals dst, it's noop. Drop the src.
2576 * cgroup_migrate() will skip the cset too. Note that we
2577 * can't handle src == dst as some nodes are used by both.
2579 if (src_cset
== dst_cset
) {
2580 src_cset
->mg_src_cgrp
= NULL
;
2581 src_cset
->mg_dst_cgrp
= NULL
;
2582 list_del_init(&src_cset
->mg_preload_node
);
2583 put_css_set(src_cset
);
2584 put_css_set(dst_cset
);
2588 src_cset
->mg_dst_cset
= dst_cset
;
2590 if (list_empty(&dst_cset
->mg_preload_node
))
2591 list_add(&dst_cset
->mg_preload_node
, &csets
);
2593 put_css_set(dst_cset
);
2596 list_splice_tail(&csets
, preloaded_csets
);
2599 cgroup_migrate_finish(&csets
);
2604 * cgroup_migrate - migrate a process or task to a cgroup
2605 * @leader: the leader of the process or the task to migrate
2606 * @threadgroup: whether @leader points to the whole process or a single task
2607 * @root: cgroup root migration is taking place on
2609 * Migrate a process or task denoted by @leader. If migrating a process,
2610 * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
2611 * responsible for invoking cgroup_migrate_add_src() and
2612 * cgroup_migrate_prepare_dst() on the targets before invoking this
2613 * function and following up with cgroup_migrate_finish().
2615 * As long as a controller's ->can_attach() doesn't fail, this function is
2616 * guaranteed to succeed. This means that, excluding ->can_attach()
2617 * failure, when migrating multiple targets, the success or failure can be
2618 * decided for all targets by invoking group_migrate_prepare_dst() before
2619 * actually starting migrating.
2621 static int cgroup_migrate(struct task_struct
*leader
, bool threadgroup
,
2622 struct cgroup_root
*root
)
2624 struct cgroup_taskset tset
= CGROUP_TASKSET_INIT(tset
);
2625 struct task_struct
*task
;
2628 * Prevent freeing of tasks while we take a snapshot. Tasks that are
2629 * already PF_EXITING could be freed from underneath us unless we
2630 * take an rcu_read_lock.
2632 spin_lock_bh(&css_set_lock
);
2636 cgroup_taskset_add(task
, &tset
);
2639 } while_each_thread(leader
, task
);
2641 spin_unlock_bh(&css_set_lock
);
2643 return cgroup_taskset_migrate(&tset
, root
);
2647 * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
2648 * @dst_cgrp: the cgroup to attach to
2649 * @leader: the task or the leader of the threadgroup to be attached
2650 * @threadgroup: attach the whole threadgroup?
2652 * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
2654 static int cgroup_attach_task(struct cgroup
*dst_cgrp
,
2655 struct task_struct
*leader
, bool threadgroup
)
2657 LIST_HEAD(preloaded_csets
);
2658 struct task_struct
*task
;
2661 if (!cgroup_may_migrate_to(dst_cgrp
))
2664 /* look up all src csets */
2665 spin_lock_bh(&css_set_lock
);
2669 cgroup_migrate_add_src(task_css_set(task
), dst_cgrp
,
2673 } while_each_thread(leader
, task
);
2675 spin_unlock_bh(&css_set_lock
);
2677 /* prepare dst csets and commit */
2678 ret
= cgroup_migrate_prepare_dst(&preloaded_csets
);
2680 ret
= cgroup_migrate(leader
, threadgroup
, dst_cgrp
->root
);
2682 cgroup_migrate_finish(&preloaded_csets
);
2686 static int cgroup_procs_write_permission(struct task_struct
*task
,
2687 struct cgroup
*dst_cgrp
,
2688 struct kernfs_open_file
*of
)
2690 const struct cred
*cred
= current_cred();
2691 const struct cred
*tcred
= get_task_cred(task
);
2695 * even if we're attaching all tasks in the thread group, we only
2696 * need to check permissions on one of them.
2698 if (!uid_eq(cred
->euid
, GLOBAL_ROOT_UID
) &&
2699 !uid_eq(cred
->euid
, tcred
->uid
) &&
2700 !uid_eq(cred
->euid
, tcred
->suid
))
2703 if (!ret
&& cgroup_on_dfl(dst_cgrp
)) {
2704 struct super_block
*sb
= of
->file
->f_path
.dentry
->d_sb
;
2705 struct cgroup
*cgrp
;
2706 struct inode
*inode
;
2708 spin_lock_bh(&css_set_lock
);
2709 cgrp
= task_cgroup_from_root(task
, &cgrp_dfl_root
);
2710 spin_unlock_bh(&css_set_lock
);
2712 while (!cgroup_is_descendant(dst_cgrp
, cgrp
))
2713 cgrp
= cgroup_parent(cgrp
);
2716 inode
= kernfs_get_inode(sb
, cgrp
->procs_file
.kn
);
2718 ret
= inode_permission(inode
, MAY_WRITE
);
2728 * Find the task_struct of the task to attach by vpid and pass it along to the
2729 * function to attach either it or all tasks in its threadgroup. Will lock
2730 * cgroup_mutex and threadgroup.
2732 static ssize_t
__cgroup_procs_write(struct kernfs_open_file
*of
, char *buf
,
2733 size_t nbytes
, loff_t off
, bool threadgroup
)
2735 struct task_struct
*tsk
;
2736 struct cgroup
*cgrp
;
2740 if (kstrtoint(strstrip(buf
), 0, &pid
) || pid
< 0)
2743 cgrp
= cgroup_kn_lock_live(of
->kn
, false);
2747 percpu_down_write(&cgroup_threadgroup_rwsem
);
2750 tsk
= find_task_by_vpid(pid
);
2753 goto out_unlock_rcu
;
2760 tsk
= tsk
->group_leader
;
2763 * Workqueue threads may acquire PF_NO_SETAFFINITY and become
2764 * trapped in a cpuset, or RT worker may be born in a cgroup
2765 * with no rt_runtime allocated. Just say no.
2767 if (tsk
== kthreadd_task
|| (tsk
->flags
& PF_NO_SETAFFINITY
)) {
2769 goto out_unlock_rcu
;
2772 get_task_struct(tsk
);
2775 ret
= cgroup_procs_write_permission(tsk
, cgrp
, of
);
2777 ret
= cgroup_attach_task(cgrp
, tsk
, threadgroup
);
2779 put_task_struct(tsk
);
2780 goto out_unlock_threadgroup
;
2784 out_unlock_threadgroup
:
2785 percpu_up_write(&cgroup_threadgroup_rwsem
);
2786 cgroup_kn_unlock(of
->kn
);
2787 cpuset_post_attach_flush();
2788 return ret
?: nbytes
;
2792 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
2793 * @from: attach to all cgroups of a given task
2794 * @tsk: the task to be attached
2796 int cgroup_attach_task_all(struct task_struct
*from
, struct task_struct
*tsk
)
2798 struct cgroup_root
*root
;
2801 mutex_lock(&cgroup_mutex
);
2802 for_each_root(root
) {
2803 struct cgroup
*from_cgrp
;
2805 if (root
== &cgrp_dfl_root
)
2808 spin_lock_bh(&css_set_lock
);
2809 from_cgrp
= task_cgroup_from_root(from
, root
);
2810 spin_unlock_bh(&css_set_lock
);
2812 retval
= cgroup_attach_task(from_cgrp
, tsk
, false);
2816 mutex_unlock(&cgroup_mutex
);
2820 EXPORT_SYMBOL_GPL(cgroup_attach_task_all
);
2822 static ssize_t
cgroup_tasks_write(struct kernfs_open_file
*of
,
2823 char *buf
, size_t nbytes
, loff_t off
)
2825 return __cgroup_procs_write(of
, buf
, nbytes
, off
, false);
2828 static ssize_t
cgroup_procs_write(struct kernfs_open_file
*of
,
2829 char *buf
, size_t nbytes
, loff_t off
)
2831 return __cgroup_procs_write(of
, buf
, nbytes
, off
, true);
2834 static ssize_t
cgroup_release_agent_write(struct kernfs_open_file
*of
,
2835 char *buf
, size_t nbytes
, loff_t off
)
2837 struct cgroup
*cgrp
;
2839 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
2841 cgrp
= cgroup_kn_lock_live(of
->kn
, false);
2844 spin_lock(&release_agent_path_lock
);
2845 strlcpy(cgrp
->root
->release_agent_path
, strstrip(buf
),
2846 sizeof(cgrp
->root
->release_agent_path
));
2847 spin_unlock(&release_agent_path_lock
);
2848 cgroup_kn_unlock(of
->kn
);
2852 static int cgroup_release_agent_show(struct seq_file
*seq
, void *v
)
2854 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
2856 spin_lock(&release_agent_path_lock
);
2857 seq_puts(seq
, cgrp
->root
->release_agent_path
);
2858 spin_unlock(&release_agent_path_lock
);
2859 seq_putc(seq
, '\n');
2863 static int cgroup_sane_behavior_show(struct seq_file
*seq
, void *v
)
2865 seq_puts(seq
, "0\n");
2869 static void cgroup_print_ss_mask(struct seq_file
*seq
, u16 ss_mask
)
2871 struct cgroup_subsys
*ss
;
2872 bool printed
= false;
2875 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
2878 seq_printf(seq
, "%s", ss
->name
);
2880 } while_each_subsys_mask();
2882 seq_putc(seq
, '\n');
2885 /* show controllers which are enabled from the parent */
2886 static int cgroup_controllers_show(struct seq_file
*seq
, void *v
)
2888 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
2890 cgroup_print_ss_mask(seq
, cgroup_control(cgrp
));
2894 /* show controllers which are enabled for a given cgroup's children */
2895 static int cgroup_subtree_control_show(struct seq_file
*seq
, void *v
)
2897 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
2899 cgroup_print_ss_mask(seq
, cgrp
->subtree_control
);
2904 * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
2905 * @cgrp: root of the subtree to update csses for
2907 * @cgrp's control masks have changed and its subtree's css associations
2908 * need to be updated accordingly. This function looks up all css_sets
2909 * which are attached to the subtree, creates the matching updated css_sets
2910 * and migrates the tasks to the new ones.
2912 static int cgroup_update_dfl_csses(struct cgroup
*cgrp
)
2914 LIST_HEAD(preloaded_csets
);
2915 struct cgroup_taskset tset
= CGROUP_TASKSET_INIT(tset
);
2916 struct cgroup_subsys_state
*d_css
;
2917 struct cgroup
*dsct
;
2918 struct css_set
*src_cset
;
2921 lockdep_assert_held(&cgroup_mutex
);
2923 percpu_down_write(&cgroup_threadgroup_rwsem
);
2925 /* look up all csses currently attached to @cgrp's subtree */
2926 spin_lock_bh(&css_set_lock
);
2927 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
2928 struct cgrp_cset_link
*link
;
2930 list_for_each_entry(link
, &dsct
->cset_links
, cset_link
)
2931 cgroup_migrate_add_src(link
->cset
, dsct
,
2934 spin_unlock_bh(&css_set_lock
);
2936 /* NULL dst indicates self on default hierarchy */
2937 ret
= cgroup_migrate_prepare_dst(&preloaded_csets
);
2941 spin_lock_bh(&css_set_lock
);
2942 list_for_each_entry(src_cset
, &preloaded_csets
, mg_preload_node
) {
2943 struct task_struct
*task
, *ntask
;
2945 /* src_csets precede dst_csets, break on the first dst_cset */
2946 if (!src_cset
->mg_src_cgrp
)
2949 /* all tasks in src_csets need to be migrated */
2950 list_for_each_entry_safe(task
, ntask
, &src_cset
->tasks
, cg_list
)
2951 cgroup_taskset_add(task
, &tset
);
2953 spin_unlock_bh(&css_set_lock
);
2955 ret
= cgroup_taskset_migrate(&tset
, cgrp
->root
);
2957 cgroup_migrate_finish(&preloaded_csets
);
2958 percpu_up_write(&cgroup_threadgroup_rwsem
);
2963 * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
2964 * @cgrp: root of the target subtree
2966 * Because css offlining is asynchronous, userland may try to re-enable a
2967 * controller while the previous css is still around. This function grabs
2968 * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
2970 static void cgroup_lock_and_drain_offline(struct cgroup
*cgrp
)
2971 __acquires(&cgroup_mutex
)
2973 struct cgroup
*dsct
;
2974 struct cgroup_subsys_state
*d_css
;
2975 struct cgroup_subsys
*ss
;
2979 mutex_lock(&cgroup_mutex
);
2981 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
2982 for_each_subsys(ss
, ssid
) {
2983 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
2986 if (!css
|| !percpu_ref_is_dying(&css
->refcnt
))
2990 prepare_to_wait(&dsct
->offline_waitq
, &wait
,
2991 TASK_UNINTERRUPTIBLE
);
2993 mutex_unlock(&cgroup_mutex
);
2995 finish_wait(&dsct
->offline_waitq
, &wait
);
3004 * cgroup_save_control - save control masks of a subtree
3005 * @cgrp: root of the target subtree
3007 * Save ->subtree_control and ->subtree_ss_mask to the respective old_
3008 * prefixed fields for @cgrp's subtree including @cgrp itself.
3010 static void cgroup_save_control(struct cgroup
*cgrp
)
3012 struct cgroup
*dsct
;
3013 struct cgroup_subsys_state
*d_css
;
3015 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
3016 dsct
->old_subtree_control
= dsct
->subtree_control
;
3017 dsct
->old_subtree_ss_mask
= dsct
->subtree_ss_mask
;
3022 * cgroup_propagate_control - refresh control masks of a subtree
3023 * @cgrp: root of the target subtree
3025 * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
3026 * ->subtree_control and propagate controller availability through the
3027 * subtree so that descendants don't have unavailable controllers enabled.
3029 static void cgroup_propagate_control(struct cgroup
*cgrp
)
3031 struct cgroup
*dsct
;
3032 struct cgroup_subsys_state
*d_css
;
3034 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
3035 dsct
->subtree_control
&= cgroup_control(dsct
);
3036 dsct
->subtree_ss_mask
=
3037 cgroup_calc_subtree_ss_mask(dsct
->subtree_control
,
3038 cgroup_ss_mask(dsct
));
3043 * cgroup_restore_control - restore control masks of a subtree
3044 * @cgrp: root of the target subtree
3046 * Restore ->subtree_control and ->subtree_ss_mask from the respective old_
3047 * prefixed fields for @cgrp's subtree including @cgrp itself.
3049 static void cgroup_restore_control(struct cgroup
*cgrp
)
3051 struct cgroup
*dsct
;
3052 struct cgroup_subsys_state
*d_css
;
3054 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
3055 dsct
->subtree_control
= dsct
->old_subtree_control
;
3056 dsct
->subtree_ss_mask
= dsct
->old_subtree_ss_mask
;
3060 static bool css_visible(struct cgroup_subsys_state
*css
)
3062 struct cgroup_subsys
*ss
= css
->ss
;
3063 struct cgroup
*cgrp
= css
->cgroup
;
3065 if (cgroup_control(cgrp
) & (1 << ss
->id
))
3067 if (!(cgroup_ss_mask(cgrp
) & (1 << ss
->id
)))
3069 return cgroup_on_dfl(cgrp
) && ss
->implicit_on_dfl
;
3073 * cgroup_apply_control_enable - enable or show csses according to control
3074 * @cgrp: root of the target subtree
3076 * Walk @cgrp's subtree and create new csses or make the existing ones
3077 * visible. A css is created invisible if it's being implicitly enabled
3078 * through dependency. An invisible css is made visible when the userland
3079 * explicitly enables it.
3081 * Returns 0 on success, -errno on failure. On failure, csses which have
3082 * been processed already aren't cleaned up. The caller is responsible for
3083 * cleaning up with cgroup_apply_control_disble().
3085 static int cgroup_apply_control_enable(struct cgroup
*cgrp
)
3087 struct cgroup
*dsct
;
3088 struct cgroup_subsys_state
*d_css
;
3089 struct cgroup_subsys
*ss
;
3092 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
3093 for_each_subsys(ss
, ssid
) {
3094 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
3096 WARN_ON_ONCE(css
&& percpu_ref_is_dying(&css
->refcnt
));
3098 if (!(cgroup_ss_mask(dsct
) & (1 << ss
->id
)))
3102 css
= css_create(dsct
, ss
);
3104 return PTR_ERR(css
);
3107 if (css_visible(css
)) {
3108 ret
= css_populate_dir(css
);
3119 * cgroup_apply_control_disable - kill or hide csses according to control
3120 * @cgrp: root of the target subtree
3122 * Walk @cgrp's subtree and kill and hide csses so that they match
3123 * cgroup_ss_mask() and cgroup_visible_mask().
3125 * A css is hidden when the userland requests it to be disabled while other
3126 * subsystems are still depending on it. The css must not actively control
3127 * resources and be in the vanilla state if it's made visible again later.
3128 * Controllers which may be depended upon should provide ->css_reset() for
3131 static void cgroup_apply_control_disable(struct cgroup
*cgrp
)
3133 struct cgroup
*dsct
;
3134 struct cgroup_subsys_state
*d_css
;
3135 struct cgroup_subsys
*ss
;
3138 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
3139 for_each_subsys(ss
, ssid
) {
3140 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
3142 WARN_ON_ONCE(css
&& percpu_ref_is_dying(&css
->refcnt
));
3148 !(cgroup_ss_mask(dsct
) & (1 << ss
->id
))) {
3150 } else if (!css_visible(css
)) {
3160 * cgroup_apply_control - apply control mask updates to the subtree
3161 * @cgrp: root of the target subtree
3163 * subsystems can be enabled and disabled in a subtree using the following
3166 * 1. Call cgroup_save_control() to stash the current state.
3167 * 2. Update ->subtree_control masks in the subtree as desired.
3168 * 3. Call cgroup_apply_control() to apply the changes.
3169 * 4. Optionally perform other related operations.
3170 * 5. Call cgroup_finalize_control() to finish up.
3172 * This function implements step 3 and propagates the mask changes
3173 * throughout @cgrp's subtree, updates csses accordingly and perform
3174 * process migrations.
3176 static int cgroup_apply_control(struct cgroup
*cgrp
)
3180 cgroup_propagate_control(cgrp
);
3182 ret
= cgroup_apply_control_enable(cgrp
);
3187 * At this point, cgroup_e_css() results reflect the new csses
3188 * making the following cgroup_update_dfl_csses() properly update
3189 * css associations of all tasks in the subtree.
3191 ret
= cgroup_update_dfl_csses(cgrp
);
3199 * cgroup_finalize_control - finalize control mask update
3200 * @cgrp: root of the target subtree
3201 * @ret: the result of the update
3203 * Finalize control mask update. See cgroup_apply_control() for more info.
3205 static void cgroup_finalize_control(struct cgroup
*cgrp
, int ret
)
3208 cgroup_restore_control(cgrp
);
3209 cgroup_propagate_control(cgrp
);
3212 cgroup_apply_control_disable(cgrp
);
3215 /* change the enabled child controllers for a cgroup in the default hierarchy */
3216 static ssize_t
cgroup_subtree_control_write(struct kernfs_open_file
*of
,
3217 char *buf
, size_t nbytes
,
3220 u16 enable
= 0, disable
= 0;
3221 struct cgroup
*cgrp
, *child
;
3222 struct cgroup_subsys
*ss
;
3227 * Parse input - space separated list of subsystem names prefixed
3228 * with either + or -.
3230 buf
= strstrip(buf
);
3231 while ((tok
= strsep(&buf
, " "))) {
3234 do_each_subsys_mask(ss
, ssid
, ~cgrp_dfl_inhibit_ss_mask
) {
3235 if (!cgroup_ssid_enabled(ssid
) ||
3236 strcmp(tok
+ 1, ss
->name
))
3240 enable
|= 1 << ssid
;
3241 disable
&= ~(1 << ssid
);
3242 } else if (*tok
== '-') {
3243 disable
|= 1 << ssid
;
3244 enable
&= ~(1 << ssid
);
3249 } while_each_subsys_mask();
3250 if (ssid
== CGROUP_SUBSYS_COUNT
)
3254 cgrp
= cgroup_kn_lock_live(of
->kn
, true);
3258 for_each_subsys(ss
, ssid
) {
3259 if (enable
& (1 << ssid
)) {
3260 if (cgrp
->subtree_control
& (1 << ssid
)) {
3261 enable
&= ~(1 << ssid
);
3265 if (!(cgroup_control(cgrp
) & (1 << ssid
))) {
3269 } else if (disable
& (1 << ssid
)) {
3270 if (!(cgrp
->subtree_control
& (1 << ssid
))) {
3271 disable
&= ~(1 << ssid
);
3275 /* a child has it enabled? */
3276 cgroup_for_each_live_child(child
, cgrp
) {
3277 if (child
->subtree_control
& (1 << ssid
)) {
3285 if (!enable
&& !disable
) {
3291 * Except for the root, subtree_control must be zero for a cgroup
3292 * with tasks so that child cgroups don't compete against tasks.
3294 if (enable
&& cgroup_parent(cgrp
) && !list_empty(&cgrp
->cset_links
)) {
3299 /* save and update control masks and prepare csses */
3300 cgroup_save_control(cgrp
);
3302 cgrp
->subtree_control
|= enable
;
3303 cgrp
->subtree_control
&= ~disable
;
3305 ret
= cgroup_apply_control(cgrp
);
3307 cgroup_finalize_control(cgrp
, ret
);
3309 kernfs_activate(cgrp
->kn
);
3312 cgroup_kn_unlock(of
->kn
);
3313 return ret
?: nbytes
;
3316 static int cgroup_events_show(struct seq_file
*seq
, void *v
)
3318 seq_printf(seq
, "populated %d\n",
3319 cgroup_is_populated(seq_css(seq
)->cgroup
));
3323 static ssize_t
cgroup_file_write(struct kernfs_open_file
*of
, char *buf
,
3324 size_t nbytes
, loff_t off
)
3326 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
3327 struct cftype
*cft
= of
->kn
->priv
;
3328 struct cgroup_subsys_state
*css
;
3332 return cft
->write(of
, buf
, nbytes
, off
);
3335 * kernfs guarantees that a file isn't deleted with operations in
3336 * flight, which means that the matching css is and stays alive and
3337 * doesn't need to be pinned. The RCU locking is not necessary
3338 * either. It's just for the convenience of using cgroup_css().
3341 css
= cgroup_css(cgrp
, cft
->ss
);
3344 if (cft
->write_u64
) {
3345 unsigned long long v
;
3346 ret
= kstrtoull(buf
, 0, &v
);
3348 ret
= cft
->write_u64(css
, cft
, v
);
3349 } else if (cft
->write_s64
) {
3351 ret
= kstrtoll(buf
, 0, &v
);
3353 ret
= cft
->write_s64(css
, cft
, v
);
3358 return ret
?: nbytes
;
3361 static void *cgroup_seqfile_start(struct seq_file
*seq
, loff_t
*ppos
)
3363 return seq_cft(seq
)->seq_start(seq
, ppos
);
3366 static void *cgroup_seqfile_next(struct seq_file
*seq
, void *v
, loff_t
*ppos
)
3368 return seq_cft(seq
)->seq_next(seq
, v
, ppos
);
3371 static void cgroup_seqfile_stop(struct seq_file
*seq
, void *v
)
3373 seq_cft(seq
)->seq_stop(seq
, v
);
3376 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
3378 struct cftype
*cft
= seq_cft(m
);
3379 struct cgroup_subsys_state
*css
= seq_css(m
);
3382 return cft
->seq_show(m
, arg
);
3385 seq_printf(m
, "%llu\n", cft
->read_u64(css
, cft
));
3386 else if (cft
->read_s64
)
3387 seq_printf(m
, "%lld\n", cft
->read_s64(css
, cft
));
3393 static struct kernfs_ops cgroup_kf_single_ops
= {
3394 .atomic_write_len
= PAGE_SIZE
,
3395 .write
= cgroup_file_write
,
3396 .seq_show
= cgroup_seqfile_show
,
3399 static struct kernfs_ops cgroup_kf_ops
= {
3400 .atomic_write_len
= PAGE_SIZE
,
3401 .write
= cgroup_file_write
,
3402 .seq_start
= cgroup_seqfile_start
,
3403 .seq_next
= cgroup_seqfile_next
,
3404 .seq_stop
= cgroup_seqfile_stop
,
3405 .seq_show
= cgroup_seqfile_show
,
3409 * cgroup_rename - Only allow simple rename of directories in place.
3411 static int cgroup_rename(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
3412 const char *new_name_str
)
3414 struct cgroup
*cgrp
= kn
->priv
;
3417 if (kernfs_type(kn
) != KERNFS_DIR
)
3419 if (kn
->parent
!= new_parent
)
3423 * This isn't a proper migration and its usefulness is very
3424 * limited. Disallow on the default hierarchy.
3426 if (cgroup_on_dfl(cgrp
))
3430 * We're gonna grab cgroup_mutex which nests outside kernfs
3431 * active_ref. kernfs_rename() doesn't require active_ref
3432 * protection. Break them before grabbing cgroup_mutex.
3434 kernfs_break_active_protection(new_parent
);
3435 kernfs_break_active_protection(kn
);
3437 mutex_lock(&cgroup_mutex
);
3439 ret
= kernfs_rename(kn
, new_parent
, new_name_str
);
3441 mutex_unlock(&cgroup_mutex
);
3443 kernfs_unbreak_active_protection(kn
);
3444 kernfs_unbreak_active_protection(new_parent
);
3448 /* set uid and gid of cgroup dirs and files to that of the creator */
3449 static int cgroup_kn_set_ugid(struct kernfs_node
*kn
)
3451 struct iattr iattr
= { .ia_valid
= ATTR_UID
| ATTR_GID
,
3452 .ia_uid
= current_fsuid(),
3453 .ia_gid
= current_fsgid(), };
3455 if (uid_eq(iattr
.ia_uid
, GLOBAL_ROOT_UID
) &&
3456 gid_eq(iattr
.ia_gid
, GLOBAL_ROOT_GID
))
3459 return kernfs_setattr(kn
, &iattr
);
3462 static int cgroup_add_file(struct cgroup_subsys_state
*css
, struct cgroup
*cgrp
,
3465 char name
[CGROUP_FILE_NAME_MAX
];
3466 struct kernfs_node
*kn
;
3467 struct lock_class_key
*key
= NULL
;
3470 #ifdef CONFIG_DEBUG_LOCK_ALLOC
3471 key
= &cft
->lockdep_key
;
3473 kn
= __kernfs_create_file(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
),
3474 cgroup_file_mode(cft
), 0, cft
->kf_ops
, cft
,
3479 ret
= cgroup_kn_set_ugid(kn
);
3485 if (cft
->file_offset
) {
3486 struct cgroup_file
*cfile
= (void *)css
+ cft
->file_offset
;
3488 spin_lock_irq(&cgroup_file_kn_lock
);
3490 spin_unlock_irq(&cgroup_file_kn_lock
);
3497 * cgroup_addrm_files - add or remove files to a cgroup directory
3498 * @css: the target css
3499 * @cgrp: the target cgroup (usually css->cgroup)
3500 * @cfts: array of cftypes to be added
3501 * @is_add: whether to add or remove
3503 * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
3504 * For removals, this function never fails.
3506 static int cgroup_addrm_files(struct cgroup_subsys_state
*css
,
3507 struct cgroup
*cgrp
, struct cftype cfts
[],
3510 struct cftype
*cft
, *cft_end
= NULL
;
3513 lockdep_assert_held(&cgroup_mutex
);
3516 for (cft
= cfts
; cft
!= cft_end
&& cft
->name
[0] != '\0'; cft
++) {
3517 /* does cft->flags tell us to skip this file on @cgrp? */
3518 if ((cft
->flags
& __CFTYPE_ONLY_ON_DFL
) && !cgroup_on_dfl(cgrp
))
3520 if ((cft
->flags
& __CFTYPE_NOT_ON_DFL
) && cgroup_on_dfl(cgrp
))
3522 if ((cft
->flags
& CFTYPE_NOT_ON_ROOT
) && !cgroup_parent(cgrp
))
3524 if ((cft
->flags
& CFTYPE_ONLY_ON_ROOT
) && cgroup_parent(cgrp
))
3528 ret
= cgroup_add_file(css
, cgrp
, cft
);
3530 pr_warn("%s: failed to add %s, err=%d\n",
3531 __func__
, cft
->name
, ret
);
3537 cgroup_rm_file(cgrp
, cft
);
3543 static int cgroup_apply_cftypes(struct cftype
*cfts
, bool is_add
)
3546 struct cgroup_subsys
*ss
= cfts
[0].ss
;
3547 struct cgroup
*root
= &ss
->root
->cgrp
;
3548 struct cgroup_subsys_state
*css
;
3551 lockdep_assert_held(&cgroup_mutex
);
3553 /* add/rm files for all cgroups created before */
3554 css_for_each_descendant_pre(css
, cgroup_css(root
, ss
)) {
3555 struct cgroup
*cgrp
= css
->cgroup
;
3557 if (!(css
->flags
& CSS_VISIBLE
))
3560 ret
= cgroup_addrm_files(css
, cgrp
, cfts
, is_add
);
3566 kernfs_activate(root
->kn
);
3570 static void cgroup_exit_cftypes(struct cftype
*cfts
)
3574 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
3575 /* free copy for custom atomic_write_len, see init_cftypes() */
3576 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
)
3581 /* revert flags set by cgroup core while adding @cfts */
3582 cft
->flags
&= ~(__CFTYPE_ONLY_ON_DFL
| __CFTYPE_NOT_ON_DFL
);
3586 static int cgroup_init_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3590 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
3591 struct kernfs_ops
*kf_ops
;
3593 WARN_ON(cft
->ss
|| cft
->kf_ops
);
3596 kf_ops
= &cgroup_kf_ops
;
3598 kf_ops
= &cgroup_kf_single_ops
;
3601 * Ugh... if @cft wants a custom max_write_len, we need to
3602 * make a copy of kf_ops to set its atomic_write_len.
3604 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
) {
3605 kf_ops
= kmemdup(kf_ops
, sizeof(*kf_ops
), GFP_KERNEL
);
3607 cgroup_exit_cftypes(cfts
);
3610 kf_ops
->atomic_write_len
= cft
->max_write_len
;
3613 cft
->kf_ops
= kf_ops
;
3620 static int cgroup_rm_cftypes_locked(struct cftype
*cfts
)
3622 lockdep_assert_held(&cgroup_mutex
);
3624 if (!cfts
|| !cfts
[0].ss
)
3627 list_del(&cfts
->node
);
3628 cgroup_apply_cftypes(cfts
, false);
3629 cgroup_exit_cftypes(cfts
);
3634 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
3635 * @cfts: zero-length name terminated array of cftypes
3637 * Unregister @cfts. Files described by @cfts are removed from all
3638 * existing cgroups and all future cgroups won't have them either. This
3639 * function can be called anytime whether @cfts' subsys is attached or not.
3641 * Returns 0 on successful unregistration, -ENOENT if @cfts is not
3644 int cgroup_rm_cftypes(struct cftype
*cfts
)
3648 mutex_lock(&cgroup_mutex
);
3649 ret
= cgroup_rm_cftypes_locked(cfts
);
3650 mutex_unlock(&cgroup_mutex
);
3655 * cgroup_add_cftypes - add an array of cftypes to a subsystem
3656 * @ss: target cgroup subsystem
3657 * @cfts: zero-length name terminated array of cftypes
3659 * Register @cfts to @ss. Files described by @cfts are created for all
3660 * existing cgroups to which @ss is attached and all future cgroups will
3661 * have them too. This function can be called anytime whether @ss is
3664 * Returns 0 on successful registration, -errno on failure. Note that this
3665 * function currently returns 0 as long as @cfts registration is successful
3666 * even if some file creation attempts on existing cgroups fail.
3668 static int cgroup_add_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3672 if (!cgroup_ssid_enabled(ss
->id
))
3675 if (!cfts
|| cfts
[0].name
[0] == '\0')
3678 ret
= cgroup_init_cftypes(ss
, cfts
);
3682 mutex_lock(&cgroup_mutex
);
3684 list_add_tail(&cfts
->node
, &ss
->cfts
);
3685 ret
= cgroup_apply_cftypes(cfts
, true);
3687 cgroup_rm_cftypes_locked(cfts
);
3689 mutex_unlock(&cgroup_mutex
);
3694 * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
3695 * @ss: target cgroup subsystem
3696 * @cfts: zero-length name terminated array of cftypes
3698 * Similar to cgroup_add_cftypes() but the added files are only used for
3699 * the default hierarchy.
3701 int cgroup_add_dfl_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3705 for (cft
= cfts
; cft
&& cft
->name
[0] != '\0'; cft
++)
3706 cft
->flags
|= __CFTYPE_ONLY_ON_DFL
;
3707 return cgroup_add_cftypes(ss
, cfts
);
3711 * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
3712 * @ss: target cgroup subsystem
3713 * @cfts: zero-length name terminated array of cftypes
3715 * Similar to cgroup_add_cftypes() but the added files are only used for
3716 * the legacy hierarchies.
3718 int cgroup_add_legacy_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3722 for (cft
= cfts
; cft
&& cft
->name
[0] != '\0'; cft
++)
3723 cft
->flags
|= __CFTYPE_NOT_ON_DFL
;
3724 return cgroup_add_cftypes(ss
, cfts
);
3728 * cgroup_file_notify - generate a file modified event for a cgroup_file
3729 * @cfile: target cgroup_file
3731 * @cfile must have been obtained by setting cftype->file_offset.
3733 void cgroup_file_notify(struct cgroup_file
*cfile
)
3735 unsigned long flags
;
3737 spin_lock_irqsave(&cgroup_file_kn_lock
, flags
);
3739 kernfs_notify(cfile
->kn
);
3740 spin_unlock_irqrestore(&cgroup_file_kn_lock
, flags
);
3744 * cgroup_task_count - count the number of tasks in a cgroup.
3745 * @cgrp: the cgroup in question
3747 * Return the number of tasks in the cgroup.
3749 static int cgroup_task_count(const struct cgroup
*cgrp
)
3752 struct cgrp_cset_link
*link
;
3754 spin_lock_bh(&css_set_lock
);
3755 list_for_each_entry(link
, &cgrp
->cset_links
, cset_link
)
3756 count
+= atomic_read(&link
->cset
->refcount
);
3757 spin_unlock_bh(&css_set_lock
);
3762 * css_next_child - find the next child of a given css
3763 * @pos: the current position (%NULL to initiate traversal)
3764 * @parent: css whose children to walk
3766 * This function returns the next child of @parent and should be called
3767 * under either cgroup_mutex or RCU read lock. The only requirement is
3768 * that @parent and @pos are accessible. The next sibling is guaranteed to
3769 * be returned regardless of their states.
3771 * If a subsystem synchronizes ->css_online() and the start of iteration, a
3772 * css which finished ->css_online() is guaranteed to be visible in the
3773 * future iterations and will stay visible until the last reference is put.
3774 * A css which hasn't finished ->css_online() or already finished
3775 * ->css_offline() may show up during traversal. It's each subsystem's
3776 * responsibility to synchronize against on/offlining.
3778 struct cgroup_subsys_state
*css_next_child(struct cgroup_subsys_state
*pos
,
3779 struct cgroup_subsys_state
*parent
)
3781 struct cgroup_subsys_state
*next
;
3783 cgroup_assert_mutex_or_rcu_locked();
3786 * @pos could already have been unlinked from the sibling list.
3787 * Once a cgroup is removed, its ->sibling.next is no longer
3788 * updated when its next sibling changes. CSS_RELEASED is set when
3789 * @pos is taken off list, at which time its next pointer is valid,
3790 * and, as releases are serialized, the one pointed to by the next
3791 * pointer is guaranteed to not have started release yet. This
3792 * implies that if we observe !CSS_RELEASED on @pos in this RCU
3793 * critical section, the one pointed to by its next pointer is
3794 * guaranteed to not have finished its RCU grace period even if we
3795 * have dropped rcu_read_lock() inbetween iterations.
3797 * If @pos has CSS_RELEASED set, its next pointer can't be
3798 * dereferenced; however, as each css is given a monotonically
3799 * increasing unique serial number and always appended to the
3800 * sibling list, the next one can be found by walking the parent's
3801 * children until the first css with higher serial number than
3802 * @pos's. While this path can be slower, it happens iff iteration
3803 * races against release and the race window is very small.
3806 next
= list_entry_rcu(parent
->children
.next
, struct cgroup_subsys_state
, sibling
);
3807 } else if (likely(!(pos
->flags
& CSS_RELEASED
))) {
3808 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup_subsys_state
, sibling
);
3810 list_for_each_entry_rcu(next
, &parent
->children
, sibling
)
3811 if (next
->serial_nr
> pos
->serial_nr
)
3816 * @next, if not pointing to the head, can be dereferenced and is
3819 if (&next
->sibling
!= &parent
->children
)
3825 * css_next_descendant_pre - find the next descendant for pre-order walk
3826 * @pos: the current position (%NULL to initiate traversal)
3827 * @root: css whose descendants to walk
3829 * To be used by css_for_each_descendant_pre(). Find the next descendant
3830 * to visit for pre-order traversal of @root's descendants. @root is
3831 * included in the iteration and the first node to be visited.
3833 * While this function requires cgroup_mutex or RCU read locking, it
3834 * doesn't require the whole traversal to be contained in a single critical
3835 * section. This function will return the correct next descendant as long
3836 * as both @pos and @root are accessible and @pos is a descendant of @root.
3838 * If a subsystem synchronizes ->css_online() and the start of iteration, a
3839 * css which finished ->css_online() is guaranteed to be visible in the
3840 * future iterations and will stay visible until the last reference is put.
3841 * A css which hasn't finished ->css_online() or already finished
3842 * ->css_offline() may show up during traversal. It's each subsystem's
3843 * responsibility to synchronize against on/offlining.
3845 struct cgroup_subsys_state
*
3846 css_next_descendant_pre(struct cgroup_subsys_state
*pos
,
3847 struct cgroup_subsys_state
*root
)
3849 struct cgroup_subsys_state
*next
;
3851 cgroup_assert_mutex_or_rcu_locked();
3853 /* if first iteration, visit @root */
3857 /* visit the first child if exists */
3858 next
= css_next_child(NULL
, pos
);
3862 /* no child, visit my or the closest ancestor's next sibling */
3863 while (pos
!= root
) {
3864 next
= css_next_child(pos
, pos
->parent
);
3874 * css_rightmost_descendant - return the rightmost descendant of a css
3875 * @pos: css of interest
3877 * Return the rightmost descendant of @pos. If there's no descendant, @pos
3878 * is returned. This can be used during pre-order traversal to skip
3881 * While this function requires cgroup_mutex or RCU read locking, it
3882 * doesn't require the whole traversal to be contained in a single critical
3883 * section. This function will return the correct rightmost descendant as
3884 * long as @pos is accessible.
3886 struct cgroup_subsys_state
*
3887 css_rightmost_descendant(struct cgroup_subsys_state
*pos
)
3889 struct cgroup_subsys_state
*last
, *tmp
;
3891 cgroup_assert_mutex_or_rcu_locked();
3895 /* ->prev isn't RCU safe, walk ->next till the end */
3897 css_for_each_child(tmp
, last
)
3904 static struct cgroup_subsys_state
*
3905 css_leftmost_descendant(struct cgroup_subsys_state
*pos
)
3907 struct cgroup_subsys_state
*last
;
3911 pos
= css_next_child(NULL
, pos
);
3918 * css_next_descendant_post - find the next descendant for post-order walk
3919 * @pos: the current position (%NULL to initiate traversal)
3920 * @root: css whose descendants to walk
3922 * To be used by css_for_each_descendant_post(). Find the next descendant
3923 * to visit for post-order traversal of @root's descendants. @root is
3924 * included in the iteration and the last node to be visited.
3926 * While this function requires cgroup_mutex or RCU read locking, it
3927 * doesn't require the whole traversal to be contained in a single critical
3928 * section. This function will return the correct next descendant as long
3929 * as both @pos and @cgroup are accessible and @pos is a descendant of
3932 * If a subsystem synchronizes ->css_online() and the start of iteration, a
3933 * css which finished ->css_online() is guaranteed to be visible in the
3934 * future iterations and will stay visible until the last reference is put.
3935 * A css which hasn't finished ->css_online() or already finished
3936 * ->css_offline() may show up during traversal. It's each subsystem's
3937 * responsibility to synchronize against on/offlining.
3939 struct cgroup_subsys_state
*
3940 css_next_descendant_post(struct cgroup_subsys_state
*pos
,
3941 struct cgroup_subsys_state
*root
)
3943 struct cgroup_subsys_state
*next
;
3945 cgroup_assert_mutex_or_rcu_locked();
3947 /* if first iteration, visit leftmost descendant which may be @root */
3949 return css_leftmost_descendant(root
);
3951 /* if we visited @root, we're done */
3955 /* if there's an unvisited sibling, visit its leftmost descendant */
3956 next
= css_next_child(pos
, pos
->parent
);
3958 return css_leftmost_descendant(next
);
3960 /* no sibling left, visit parent */
3965 * css_has_online_children - does a css have online children
3966 * @css: the target css
3968 * Returns %true if @css has any online children; otherwise, %false. This
3969 * function can be called from any context but the caller is responsible
3970 * for synchronizing against on/offlining as necessary.
3972 bool css_has_online_children(struct cgroup_subsys_state
*css
)
3974 struct cgroup_subsys_state
*child
;
3978 css_for_each_child(child
, css
) {
3979 if (child
->flags
& CSS_ONLINE
) {
3989 * css_task_iter_advance_css_set - advance a task itererator to the next css_set
3990 * @it: the iterator to advance
3992 * Advance @it to the next css_set to walk.
3994 static void css_task_iter_advance_css_set(struct css_task_iter
*it
)
3996 struct list_head
*l
= it
->cset_pos
;
3997 struct cgrp_cset_link
*link
;
3998 struct css_set
*cset
;
4000 lockdep_assert_held(&css_set_lock
);
4002 /* Advance to the next non-empty css_set */
4005 if (l
== it
->cset_head
) {
4006 it
->cset_pos
= NULL
;
4007 it
->task_pos
= NULL
;
4012 cset
= container_of(l
, struct css_set
,
4013 e_cset_node
[it
->ss
->id
]);
4015 link
= list_entry(l
, struct cgrp_cset_link
, cset_link
);
4018 } while (!css_set_populated(cset
));
4022 if (!list_empty(&cset
->tasks
))
4023 it
->task_pos
= cset
->tasks
.next
;
4025 it
->task_pos
= cset
->mg_tasks
.next
;
4027 it
->tasks_head
= &cset
->tasks
;
4028 it
->mg_tasks_head
= &cset
->mg_tasks
;
4031 * We don't keep css_sets locked across iteration steps and thus
4032 * need to take steps to ensure that iteration can be resumed after
4033 * the lock is re-acquired. Iteration is performed at two levels -
4034 * css_sets and tasks in them.
4036 * Once created, a css_set never leaves its cgroup lists, so a
4037 * pinned css_set is guaranteed to stay put and we can resume
4038 * iteration afterwards.
4040 * Tasks may leave @cset across iteration steps. This is resolved
4041 * by registering each iterator with the css_set currently being
4042 * walked and making css_set_move_task() advance iterators whose
4043 * next task is leaving.
4046 list_del(&it
->iters_node
);
4047 put_css_set_locked(it
->cur_cset
);
4050 it
->cur_cset
= cset
;
4051 list_add(&it
->iters_node
, &cset
->task_iters
);
4054 static void css_task_iter_advance(struct css_task_iter
*it
)
4056 struct list_head
*l
= it
->task_pos
;
4058 lockdep_assert_held(&css_set_lock
);
4062 * Advance iterator to find next entry. cset->tasks is consumed
4063 * first and then ->mg_tasks. After ->mg_tasks, we move onto the
4068 if (l
== it
->tasks_head
)
4069 l
= it
->mg_tasks_head
->next
;
4071 if (l
== it
->mg_tasks_head
)
4072 css_task_iter_advance_css_set(it
);
4078 * css_task_iter_start - initiate task iteration
4079 * @css: the css to walk tasks of
4080 * @it: the task iterator to use
4082 * Initiate iteration through the tasks of @css. The caller can call
4083 * css_task_iter_next() to walk through the tasks until the function
4084 * returns NULL. On completion of iteration, css_task_iter_end() must be
4087 void css_task_iter_start(struct cgroup_subsys_state
*css
,
4088 struct css_task_iter
*it
)
4090 /* no one should try to iterate before mounting cgroups */
4091 WARN_ON_ONCE(!use_task_css_set_links
);
4093 memset(it
, 0, sizeof(*it
));
4095 spin_lock_bh(&css_set_lock
);
4100 it
->cset_pos
= &css
->cgroup
->e_csets
[css
->ss
->id
];
4102 it
->cset_pos
= &css
->cgroup
->cset_links
;
4104 it
->cset_head
= it
->cset_pos
;
4106 css_task_iter_advance_css_set(it
);
4108 spin_unlock_bh(&css_set_lock
);
4112 * css_task_iter_next - return the next task for the iterator
4113 * @it: the task iterator being iterated
4115 * The "next" function for task iteration. @it should have been
4116 * initialized via css_task_iter_start(). Returns NULL when the iteration
4119 struct task_struct
*css_task_iter_next(struct css_task_iter
*it
)
4122 put_task_struct(it
->cur_task
);
4123 it
->cur_task
= NULL
;
4126 spin_lock_bh(&css_set_lock
);
4129 it
->cur_task
= list_entry(it
->task_pos
, struct task_struct
,
4131 get_task_struct(it
->cur_task
);
4132 css_task_iter_advance(it
);
4135 spin_unlock_bh(&css_set_lock
);
4137 return it
->cur_task
;
4141 * css_task_iter_end - finish task iteration
4142 * @it: the task iterator to finish
4144 * Finish task iteration started by css_task_iter_start().
4146 void css_task_iter_end(struct css_task_iter
*it
)
4149 spin_lock_bh(&css_set_lock
);
4150 list_del(&it
->iters_node
);
4151 put_css_set_locked(it
->cur_cset
);
4152 spin_unlock_bh(&css_set_lock
);
4156 put_task_struct(it
->cur_task
);
4160 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
4161 * @to: cgroup to which the tasks will be moved
4162 * @from: cgroup in which the tasks currently reside
4164 * Locking rules between cgroup_post_fork() and the migration path
4165 * guarantee that, if a task is forking while being migrated, the new child
4166 * is guaranteed to be either visible in the source cgroup after the
4167 * parent's migration is complete or put into the target cgroup. No task
4168 * can slip out of migration through forking.
4170 int cgroup_transfer_tasks(struct cgroup
*to
, struct cgroup
*from
)
4172 LIST_HEAD(preloaded_csets
);
4173 struct cgrp_cset_link
*link
;
4174 struct css_task_iter it
;
4175 struct task_struct
*task
;
4178 if (!cgroup_may_migrate_to(to
))
4181 mutex_lock(&cgroup_mutex
);
4183 /* all tasks in @from are being moved, all csets are source */
4184 spin_lock_bh(&css_set_lock
);
4185 list_for_each_entry(link
, &from
->cset_links
, cset_link
)
4186 cgroup_migrate_add_src(link
->cset
, to
, &preloaded_csets
);
4187 spin_unlock_bh(&css_set_lock
);
4189 ret
= cgroup_migrate_prepare_dst(&preloaded_csets
);
4194 * Migrate tasks one-by-one until @from is empty. This fails iff
4195 * ->can_attach() fails.
4198 css_task_iter_start(&from
->self
, &it
);
4199 task
= css_task_iter_next(&it
);
4201 get_task_struct(task
);
4202 css_task_iter_end(&it
);
4205 ret
= cgroup_migrate(task
, false, to
->root
);
4206 put_task_struct(task
);
4208 } while (task
&& !ret
);
4210 cgroup_migrate_finish(&preloaded_csets
);
4211 mutex_unlock(&cgroup_mutex
);
4216 * Stuff for reading the 'tasks'/'procs' files.
4218 * Reading this file can return large amounts of data if a cgroup has
4219 * *lots* of attached tasks. So it may need several calls to read(),
4220 * but we cannot guarantee that the information we produce is correct
4221 * unless we produce it entirely atomically.
4225 /* which pidlist file are we talking about? */
4226 enum cgroup_filetype
{
4232 * A pidlist is a list of pids that virtually represents the contents of one
4233 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
4234 * a pair (one each for procs, tasks) for each pid namespace that's relevant
4237 struct cgroup_pidlist
{
4239 * used to find which pidlist is wanted. doesn't change as long as
4240 * this particular list stays in the list.
4242 struct { enum cgroup_filetype type
; struct pid_namespace
*ns
; } key
;
4245 /* how many elements the above list has */
4247 /* each of these stored in a list by its cgroup */
4248 struct list_head links
;
4249 /* pointer to the cgroup we belong to, for list removal purposes */
4250 struct cgroup
*owner
;
4251 /* for delayed destruction */
4252 struct delayed_work destroy_dwork
;
4256 * The following two functions "fix" the issue where there are more pids
4257 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
4258 * TODO: replace with a kernel-wide solution to this problem
4260 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
4261 static void *pidlist_allocate(int count
)
4263 if (PIDLIST_TOO_LARGE(count
))
4264 return vmalloc(count
* sizeof(pid_t
));
4266 return kmalloc(count
* sizeof(pid_t
), GFP_KERNEL
);
4269 static void pidlist_free(void *p
)
4275 * Used to destroy all pidlists lingering waiting for destroy timer. None
4276 * should be left afterwards.
4278 static void cgroup_pidlist_destroy_all(struct cgroup
*cgrp
)
4280 struct cgroup_pidlist
*l
, *tmp_l
;
4282 mutex_lock(&cgrp
->pidlist_mutex
);
4283 list_for_each_entry_safe(l
, tmp_l
, &cgrp
->pidlists
, links
)
4284 mod_delayed_work(cgroup_pidlist_destroy_wq
, &l
->destroy_dwork
, 0);
4285 mutex_unlock(&cgrp
->pidlist_mutex
);
4287 flush_workqueue(cgroup_pidlist_destroy_wq
);
4288 BUG_ON(!list_empty(&cgrp
->pidlists
));
4291 static void cgroup_pidlist_destroy_work_fn(struct work_struct
*work
)
4293 struct delayed_work
*dwork
= to_delayed_work(work
);
4294 struct cgroup_pidlist
*l
= container_of(dwork
, struct cgroup_pidlist
,
4296 struct cgroup_pidlist
*tofree
= NULL
;
4298 mutex_lock(&l
->owner
->pidlist_mutex
);
4301 * Destroy iff we didn't get queued again. The state won't change
4302 * as destroy_dwork can only be queued while locked.
4304 if (!delayed_work_pending(dwork
)) {
4305 list_del(&l
->links
);
4306 pidlist_free(l
->list
);
4307 put_pid_ns(l
->key
.ns
);
4311 mutex_unlock(&l
->owner
->pidlist_mutex
);
4316 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
4317 * Returns the number of unique elements.
4319 static int pidlist_uniq(pid_t
*list
, int length
)
4324 * we presume the 0th element is unique, so i starts at 1. trivial
4325 * edge cases first; no work needs to be done for either
4327 if (length
== 0 || length
== 1)
4329 /* src and dest walk down the list; dest counts unique elements */
4330 for (src
= 1; src
< length
; src
++) {
4331 /* find next unique element */
4332 while (list
[src
] == list
[src
-1]) {
4337 /* dest always points to where the next unique element goes */
4338 list
[dest
] = list
[src
];
4346 * The two pid files - task and cgroup.procs - guaranteed that the result
4347 * is sorted, which forced this whole pidlist fiasco. As pid order is
4348 * different per namespace, each namespace needs differently sorted list,
4349 * making it impossible to use, for example, single rbtree of member tasks
4350 * sorted by task pointer. As pidlists can be fairly large, allocating one
4351 * per open file is dangerous, so cgroup had to implement shared pool of
4352 * pidlists keyed by cgroup and namespace.
4354 * All this extra complexity was caused by the original implementation
4355 * committing to an entirely unnecessary property. In the long term, we
4356 * want to do away with it. Explicitly scramble sort order if on the
4357 * default hierarchy so that no such expectation exists in the new
4360 * Scrambling is done by swapping every two consecutive bits, which is
4361 * non-identity one-to-one mapping which disturbs sort order sufficiently.
4363 static pid_t
pid_fry(pid_t pid
)
4365 unsigned a
= pid
& 0x55555555;
4366 unsigned b
= pid
& 0xAAAAAAAA;
4368 return (a
<< 1) | (b
>> 1);
4371 static pid_t
cgroup_pid_fry(struct cgroup
*cgrp
, pid_t pid
)
4373 if (cgroup_on_dfl(cgrp
))
4374 return pid_fry(pid
);
4379 static int cmppid(const void *a
, const void *b
)
4381 return *(pid_t
*)a
- *(pid_t
*)b
;
4384 static int fried_cmppid(const void *a
, const void *b
)
4386 return pid_fry(*(pid_t
*)a
) - pid_fry(*(pid_t
*)b
);
4389 static struct cgroup_pidlist
*cgroup_pidlist_find(struct cgroup
*cgrp
,
4390 enum cgroup_filetype type
)
4392 struct cgroup_pidlist
*l
;
4393 /* don't need task_nsproxy() if we're looking at ourself */
4394 struct pid_namespace
*ns
= task_active_pid_ns(current
);
4396 lockdep_assert_held(&cgrp
->pidlist_mutex
);
4398 list_for_each_entry(l
, &cgrp
->pidlists
, links
)
4399 if (l
->key
.type
== type
&& l
->key
.ns
== ns
)
4405 * find the appropriate pidlist for our purpose (given procs vs tasks)
4406 * returns with the lock on that pidlist already held, and takes care
4407 * of the use count, or returns NULL with no locks held if we're out of
4410 static struct cgroup_pidlist
*cgroup_pidlist_find_create(struct cgroup
*cgrp
,
4411 enum cgroup_filetype type
)
4413 struct cgroup_pidlist
*l
;
4415 lockdep_assert_held(&cgrp
->pidlist_mutex
);
4417 l
= cgroup_pidlist_find(cgrp
, type
);
4421 /* entry not found; create a new one */
4422 l
= kzalloc(sizeof(struct cgroup_pidlist
), GFP_KERNEL
);
4426 INIT_DELAYED_WORK(&l
->destroy_dwork
, cgroup_pidlist_destroy_work_fn
);
4428 /* don't need task_nsproxy() if we're looking at ourself */
4429 l
->key
.ns
= get_pid_ns(task_active_pid_ns(current
));
4431 list_add(&l
->links
, &cgrp
->pidlists
);
4436 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
4438 static int pidlist_array_load(struct cgroup
*cgrp
, enum cgroup_filetype type
,
4439 struct cgroup_pidlist
**lp
)
4443 int pid
, n
= 0; /* used for populating the array */
4444 struct css_task_iter it
;
4445 struct task_struct
*tsk
;
4446 struct cgroup_pidlist
*l
;
4448 lockdep_assert_held(&cgrp
->pidlist_mutex
);
4451 * If cgroup gets more users after we read count, we won't have
4452 * enough space - tough. This race is indistinguishable to the
4453 * caller from the case that the additional cgroup users didn't
4454 * show up until sometime later on.
4456 length
= cgroup_task_count(cgrp
);
4457 array
= pidlist_allocate(length
);
4460 /* now, populate the array */
4461 css_task_iter_start(&cgrp
->self
, &it
);
4462 while ((tsk
= css_task_iter_next(&it
))) {
4463 if (unlikely(n
== length
))
4465 /* get tgid or pid for procs or tasks file respectively */
4466 if (type
== CGROUP_FILE_PROCS
)
4467 pid
= task_tgid_vnr(tsk
);
4469 pid
= task_pid_vnr(tsk
);
4470 if (pid
> 0) /* make sure to only use valid results */
4473 css_task_iter_end(&it
);
4475 /* now sort & (if procs) strip out duplicates */
4476 if (cgroup_on_dfl(cgrp
))
4477 sort(array
, length
, sizeof(pid_t
), fried_cmppid
, NULL
);
4479 sort(array
, length
, sizeof(pid_t
), cmppid
, NULL
);
4480 if (type
== CGROUP_FILE_PROCS
)
4481 length
= pidlist_uniq(array
, length
);
4483 l
= cgroup_pidlist_find_create(cgrp
, type
);
4485 pidlist_free(array
);
4489 /* store array, freeing old if necessary */
4490 pidlist_free(l
->list
);
4498 * cgroupstats_build - build and fill cgroupstats
4499 * @stats: cgroupstats to fill information into
4500 * @dentry: A dentry entry belonging to the cgroup for which stats have
4503 * Build and fill cgroupstats so that taskstats can export it to user
4506 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
4508 struct kernfs_node
*kn
= kernfs_node_from_dentry(dentry
);
4509 struct cgroup
*cgrp
;
4510 struct css_task_iter it
;
4511 struct task_struct
*tsk
;
4513 /* it should be kernfs_node belonging to cgroupfs and is a directory */
4514 if (dentry
->d_sb
->s_type
!= &cgroup_fs_type
|| !kn
||
4515 kernfs_type(kn
) != KERNFS_DIR
)
4518 mutex_lock(&cgroup_mutex
);
4521 * We aren't being called from kernfs and there's no guarantee on
4522 * @kn->priv's validity. For this and css_tryget_online_from_dir(),
4523 * @kn->priv is RCU safe. Let's do the RCU dancing.
4526 cgrp
= rcu_dereference(kn
->priv
);
4527 if (!cgrp
|| cgroup_is_dead(cgrp
)) {
4529 mutex_unlock(&cgroup_mutex
);
4534 css_task_iter_start(&cgrp
->self
, &it
);
4535 while ((tsk
= css_task_iter_next(&it
))) {
4536 switch (tsk
->state
) {
4538 stats
->nr_running
++;
4540 case TASK_INTERRUPTIBLE
:
4541 stats
->nr_sleeping
++;
4543 case TASK_UNINTERRUPTIBLE
:
4544 stats
->nr_uninterruptible
++;
4547 stats
->nr_stopped
++;
4550 if (delayacct_is_task_waiting_on_io(tsk
))
4551 stats
->nr_io_wait
++;
4555 css_task_iter_end(&it
);
4557 mutex_unlock(&cgroup_mutex
);
4563 * seq_file methods for the tasks/procs files. The seq_file position is the
4564 * next pid to display; the seq_file iterator is a pointer to the pid
4565 * in the cgroup->l->list array.
4568 static void *cgroup_pidlist_start(struct seq_file
*s
, loff_t
*pos
)
4571 * Initially we receive a position value that corresponds to
4572 * one more than the last pid shown (or 0 on the first call or
4573 * after a seek to the start). Use a binary-search to find the
4574 * next pid to display, if any
4576 struct kernfs_open_file
*of
= s
->private;
4577 struct cgroup
*cgrp
= seq_css(s
)->cgroup
;
4578 struct cgroup_pidlist
*l
;
4579 enum cgroup_filetype type
= seq_cft(s
)->private;
4580 int index
= 0, pid
= *pos
;
4583 mutex_lock(&cgrp
->pidlist_mutex
);
4586 * !NULL @of->priv indicates that this isn't the first start()
4587 * after open. If the matching pidlist is around, we can use that.
4588 * Look for it. Note that @of->priv can't be used directly. It
4589 * could already have been destroyed.
4592 of
->priv
= cgroup_pidlist_find(cgrp
, type
);
4595 * Either this is the first start() after open or the matching
4596 * pidlist has been destroyed inbetween. Create a new one.
4599 ret
= pidlist_array_load(cgrp
, type
,
4600 (struct cgroup_pidlist
**)&of
->priv
);
4602 return ERR_PTR(ret
);
4607 int end
= l
->length
;
4609 while (index
< end
) {
4610 int mid
= (index
+ end
) / 2;
4611 if (cgroup_pid_fry(cgrp
, l
->list
[mid
]) == pid
) {
4614 } else if (cgroup_pid_fry(cgrp
, l
->list
[mid
]) <= pid
)
4620 /* If we're off the end of the array, we're done */
4621 if (index
>= l
->length
)
4623 /* Update the abstract position to be the actual pid that we found */
4624 iter
= l
->list
+ index
;
4625 *pos
= cgroup_pid_fry(cgrp
, *iter
);
4629 static void cgroup_pidlist_stop(struct seq_file
*s
, void *v
)
4631 struct kernfs_open_file
*of
= s
->private;
4632 struct cgroup_pidlist
*l
= of
->priv
;
4635 mod_delayed_work(cgroup_pidlist_destroy_wq
, &l
->destroy_dwork
,
4636 CGROUP_PIDLIST_DESTROY_DELAY
);
4637 mutex_unlock(&seq_css(s
)->cgroup
->pidlist_mutex
);
4640 static void *cgroup_pidlist_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
4642 struct kernfs_open_file
*of
= s
->private;
4643 struct cgroup_pidlist
*l
= of
->priv
;
4645 pid_t
*end
= l
->list
+ l
->length
;
4647 * Advance to the next pid in the array. If this goes off the
4654 *pos
= cgroup_pid_fry(seq_css(s
)->cgroup
, *p
);
4659 static int cgroup_pidlist_show(struct seq_file
*s
, void *v
)
4661 seq_printf(s
, "%d\n", *(int *)v
);
4666 static u64
cgroup_read_notify_on_release(struct cgroup_subsys_state
*css
,
4669 return notify_on_release(css
->cgroup
);
4672 static int cgroup_write_notify_on_release(struct cgroup_subsys_state
*css
,
4673 struct cftype
*cft
, u64 val
)
4676 set_bit(CGRP_NOTIFY_ON_RELEASE
, &css
->cgroup
->flags
);
4678 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &css
->cgroup
->flags
);
4682 static u64
cgroup_clone_children_read(struct cgroup_subsys_state
*css
,
4685 return test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
4688 static int cgroup_clone_children_write(struct cgroup_subsys_state
*css
,
4689 struct cftype
*cft
, u64 val
)
4692 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
4694 clear_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
4698 /* cgroup core interface files for the default hierarchy */
4699 static struct cftype cgroup_dfl_base_files
[] = {
4701 .name
= "cgroup.procs",
4702 .file_offset
= offsetof(struct cgroup
, procs_file
),
4703 .seq_start
= cgroup_pidlist_start
,
4704 .seq_next
= cgroup_pidlist_next
,
4705 .seq_stop
= cgroup_pidlist_stop
,
4706 .seq_show
= cgroup_pidlist_show
,
4707 .private = CGROUP_FILE_PROCS
,
4708 .write
= cgroup_procs_write
,
4711 .name
= "cgroup.controllers",
4712 .seq_show
= cgroup_controllers_show
,
4715 .name
= "cgroup.subtree_control",
4716 .seq_show
= cgroup_subtree_control_show
,
4717 .write
= cgroup_subtree_control_write
,
4720 .name
= "cgroup.events",
4721 .flags
= CFTYPE_NOT_ON_ROOT
,
4722 .file_offset
= offsetof(struct cgroup
, events_file
),
4723 .seq_show
= cgroup_events_show
,
4728 /* cgroup core interface files for the legacy hierarchies */
4729 static struct cftype cgroup_legacy_base_files
[] = {
4731 .name
= "cgroup.procs",
4732 .seq_start
= cgroup_pidlist_start
,
4733 .seq_next
= cgroup_pidlist_next
,
4734 .seq_stop
= cgroup_pidlist_stop
,
4735 .seq_show
= cgroup_pidlist_show
,
4736 .private = CGROUP_FILE_PROCS
,
4737 .write
= cgroup_procs_write
,
4740 .name
= "cgroup.clone_children",
4741 .read_u64
= cgroup_clone_children_read
,
4742 .write_u64
= cgroup_clone_children_write
,
4745 .name
= "cgroup.sane_behavior",
4746 .flags
= CFTYPE_ONLY_ON_ROOT
,
4747 .seq_show
= cgroup_sane_behavior_show
,
4751 .seq_start
= cgroup_pidlist_start
,
4752 .seq_next
= cgroup_pidlist_next
,
4753 .seq_stop
= cgroup_pidlist_stop
,
4754 .seq_show
= cgroup_pidlist_show
,
4755 .private = CGROUP_FILE_TASKS
,
4756 .write
= cgroup_tasks_write
,
4759 .name
= "notify_on_release",
4760 .read_u64
= cgroup_read_notify_on_release
,
4761 .write_u64
= cgroup_write_notify_on_release
,
4764 .name
= "release_agent",
4765 .flags
= CFTYPE_ONLY_ON_ROOT
,
4766 .seq_show
= cgroup_release_agent_show
,
4767 .write
= cgroup_release_agent_write
,
4768 .max_write_len
= PATH_MAX
- 1,
4774 * css destruction is four-stage process.
4776 * 1. Destruction starts. Killing of the percpu_ref is initiated.
4777 * Implemented in kill_css().
4779 * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
4780 * and thus css_tryget_online() is guaranteed to fail, the css can be
4781 * offlined by invoking offline_css(). After offlining, the base ref is
4782 * put. Implemented in css_killed_work_fn().
4784 * 3. When the percpu_ref reaches zero, the only possible remaining
4785 * accessors are inside RCU read sections. css_release() schedules the
4788 * 4. After the grace period, the css can be freed. Implemented in
4789 * css_free_work_fn().
4791 * It is actually hairier because both step 2 and 4 require process context
4792 * and thus involve punting to css->destroy_work adding two additional
4793 * steps to the already complex sequence.
4795 static void css_free_work_fn(struct work_struct
*work
)
4797 struct cgroup_subsys_state
*css
=
4798 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
4799 struct cgroup_subsys
*ss
= css
->ss
;
4800 struct cgroup
*cgrp
= css
->cgroup
;
4802 percpu_ref_exit(&css
->refcnt
);
4806 struct cgroup_subsys_state
*parent
= css
->parent
;
4810 cgroup_idr_remove(&ss
->css_idr
, id
);
4816 /* cgroup free path */
4817 atomic_dec(&cgrp
->root
->nr_cgrps
);
4818 cgroup_pidlist_destroy_all(cgrp
);
4819 cancel_work_sync(&cgrp
->release_agent_work
);
4821 if (cgroup_parent(cgrp
)) {
4823 * We get a ref to the parent, and put the ref when
4824 * this cgroup is being freed, so it's guaranteed
4825 * that the parent won't be destroyed before its
4828 cgroup_put(cgroup_parent(cgrp
));
4829 kernfs_put(cgrp
->kn
);
4833 * This is root cgroup's refcnt reaching zero,
4834 * which indicates that the root should be
4837 cgroup_destroy_root(cgrp
->root
);
4842 static void css_free_rcu_fn(struct rcu_head
*rcu_head
)
4844 struct cgroup_subsys_state
*css
=
4845 container_of(rcu_head
, struct cgroup_subsys_state
, rcu_head
);
4847 INIT_WORK(&css
->destroy_work
, css_free_work_fn
);
4848 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
4851 static void css_release_work_fn(struct work_struct
*work
)
4853 struct cgroup_subsys_state
*css
=
4854 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
4855 struct cgroup_subsys
*ss
= css
->ss
;
4856 struct cgroup
*cgrp
= css
->cgroup
;
4858 mutex_lock(&cgroup_mutex
);
4860 css
->flags
|= CSS_RELEASED
;
4861 list_del_rcu(&css
->sibling
);
4864 /* css release path */
4865 cgroup_idr_replace(&ss
->css_idr
, NULL
, css
->id
);
4866 if (ss
->css_released
)
4867 ss
->css_released(css
);
4869 /* cgroup release path */
4870 cgroup_idr_remove(&cgrp
->root
->cgroup_idr
, cgrp
->id
);
4874 * There are two control paths which try to determine
4875 * cgroup from dentry without going through kernfs -
4876 * cgroupstats_build() and css_tryget_online_from_dir().
4877 * Those are supported by RCU protecting clearing of
4878 * cgrp->kn->priv backpointer.
4881 RCU_INIT_POINTER(*(void __rcu __force
**)&cgrp
->kn
->priv
,
4885 mutex_unlock(&cgroup_mutex
);
4887 call_rcu(&css
->rcu_head
, css_free_rcu_fn
);
4890 static void css_release(struct percpu_ref
*ref
)
4892 struct cgroup_subsys_state
*css
=
4893 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
4895 INIT_WORK(&css
->destroy_work
, css_release_work_fn
);
4896 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
4899 static void init_and_link_css(struct cgroup_subsys_state
*css
,
4900 struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4902 lockdep_assert_held(&cgroup_mutex
);
4906 memset(css
, 0, sizeof(*css
));
4909 INIT_LIST_HEAD(&css
->sibling
);
4910 INIT_LIST_HEAD(&css
->children
);
4911 css
->serial_nr
= css_serial_nr_next
++;
4912 atomic_set(&css
->online_cnt
, 0);
4914 if (cgroup_parent(cgrp
)) {
4915 css
->parent
= cgroup_css(cgroup_parent(cgrp
), ss
);
4916 css_get(css
->parent
);
4919 BUG_ON(cgroup_css(cgrp
, ss
));
4922 /* invoke ->css_online() on a new CSS and mark it online if successful */
4923 static int online_css(struct cgroup_subsys_state
*css
)
4925 struct cgroup_subsys
*ss
= css
->ss
;
4928 lockdep_assert_held(&cgroup_mutex
);
4931 ret
= ss
->css_online(css
);
4933 css
->flags
|= CSS_ONLINE
;
4934 rcu_assign_pointer(css
->cgroup
->subsys
[ss
->id
], css
);
4936 atomic_inc(&css
->online_cnt
);
4938 atomic_inc(&css
->parent
->online_cnt
);
4943 /* if the CSS is online, invoke ->css_offline() on it and mark it offline */
4944 static void offline_css(struct cgroup_subsys_state
*css
)
4946 struct cgroup_subsys
*ss
= css
->ss
;
4948 lockdep_assert_held(&cgroup_mutex
);
4950 if (!(css
->flags
& CSS_ONLINE
))
4956 if (ss
->css_offline
)
4957 ss
->css_offline(css
);
4959 css
->flags
&= ~CSS_ONLINE
;
4960 RCU_INIT_POINTER(css
->cgroup
->subsys
[ss
->id
], NULL
);
4962 wake_up_all(&css
->cgroup
->offline_waitq
);
4966 * css_create - create a cgroup_subsys_state
4967 * @cgrp: the cgroup new css will be associated with
4968 * @ss: the subsys of new css
4970 * Create a new css associated with @cgrp - @ss pair. On success, the new
4971 * css is online and installed in @cgrp. This function doesn't create the
4972 * interface files. Returns 0 on success, -errno on failure.
4974 static struct cgroup_subsys_state
*css_create(struct cgroup
*cgrp
,
4975 struct cgroup_subsys
*ss
)
4977 struct cgroup
*parent
= cgroup_parent(cgrp
);
4978 struct cgroup_subsys_state
*parent_css
= cgroup_css(parent
, ss
);
4979 struct cgroup_subsys_state
*css
;
4982 lockdep_assert_held(&cgroup_mutex
);
4984 css
= ss
->css_alloc(parent_css
);
4988 init_and_link_css(css
, ss
, cgrp
);
4990 err
= percpu_ref_init(&css
->refcnt
, css_release
, 0, GFP_KERNEL
);
4994 err
= cgroup_idr_alloc(&ss
->css_idr
, NULL
, 2, 0, GFP_KERNEL
);
4996 goto err_free_percpu_ref
;
4999 /* @css is ready to be brought online now, make it visible */
5000 list_add_tail_rcu(&css
->sibling
, &parent_css
->children
);
5001 cgroup_idr_replace(&ss
->css_idr
, css
, css
->id
);
5003 err
= online_css(css
);
5007 if (ss
->broken_hierarchy
&& !ss
->warned_broken_hierarchy
&&
5008 cgroup_parent(parent
)) {
5009 pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
5010 current
->comm
, current
->pid
, ss
->name
);
5011 if (!strcmp(ss
->name
, "memory"))
5012 pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
5013 ss
->warned_broken_hierarchy
= true;
5019 list_del_rcu(&css
->sibling
);
5020 cgroup_idr_remove(&ss
->css_idr
, css
->id
);
5021 err_free_percpu_ref
:
5022 percpu_ref_exit(&css
->refcnt
);
5024 call_rcu(&css
->rcu_head
, css_free_rcu_fn
);
5025 return ERR_PTR(err
);
5028 static struct cgroup
*cgroup_create(struct cgroup
*parent
)
5030 struct cgroup_root
*root
= parent
->root
;
5031 struct cgroup
*cgrp
, *tcgrp
;
5032 int level
= parent
->level
+ 1;
5035 /* allocate the cgroup and its ID, 0 is reserved for the root */
5036 cgrp
= kzalloc(sizeof(*cgrp
) +
5037 sizeof(cgrp
->ancestor_ids
[0]) * (level
+ 1), GFP_KERNEL
);
5039 return ERR_PTR(-ENOMEM
);
5041 ret
= percpu_ref_init(&cgrp
->self
.refcnt
, css_release
, 0, GFP_KERNEL
);
5046 * Temporarily set the pointer to NULL, so idr_find() won't return
5047 * a half-baked cgroup.
5049 cgrp
->id
= cgroup_idr_alloc(&root
->cgroup_idr
, NULL
, 2, 0, GFP_KERNEL
);
5052 goto out_cancel_ref
;
5055 init_cgroup_housekeeping(cgrp
);
5057 cgrp
->self
.parent
= &parent
->self
;
5059 cgrp
->level
= level
;
5061 for (tcgrp
= cgrp
; tcgrp
; tcgrp
= cgroup_parent(tcgrp
))
5062 cgrp
->ancestor_ids
[tcgrp
->level
] = tcgrp
->id
;
5064 if (notify_on_release(parent
))
5065 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
5067 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
))
5068 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
5070 cgrp
->self
.serial_nr
= css_serial_nr_next
++;
5072 /* allocation complete, commit to creation */
5073 list_add_tail_rcu(&cgrp
->self
.sibling
, &cgroup_parent(cgrp
)->self
.children
);
5074 atomic_inc(&root
->nr_cgrps
);
5078 * @cgrp is now fully operational. If something fails after this
5079 * point, it'll be released via the normal destruction path.
5081 cgroup_idr_replace(&root
->cgroup_idr
, cgrp
, cgrp
->id
);
5084 * On the default hierarchy, a child doesn't automatically inherit
5085 * subtree_control from the parent. Each is configured manually.
5087 if (!cgroup_on_dfl(cgrp
))
5088 cgrp
->subtree_control
= cgroup_control(cgrp
);
5090 cgroup_propagate_control(cgrp
);
5092 /* @cgrp doesn't have dir yet so the following will only create csses */
5093 ret
= cgroup_apply_control_enable(cgrp
);
5100 percpu_ref_exit(&cgrp
->self
.refcnt
);
5103 return ERR_PTR(ret
);
5105 cgroup_destroy_locked(cgrp
);
5106 return ERR_PTR(ret
);
5109 static int cgroup_mkdir(struct kernfs_node
*parent_kn
, const char *name
,
5112 struct cgroup
*parent
, *cgrp
;
5113 struct kernfs_node
*kn
;
5116 /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
5117 if (strchr(name
, '\n'))
5120 parent
= cgroup_kn_lock_live(parent_kn
, false);
5124 cgrp
= cgroup_create(parent
);
5126 ret
= PTR_ERR(cgrp
);
5130 /* create the directory */
5131 kn
= kernfs_create_dir(parent
->kn
, name
, mode
, cgrp
);
5139 * This extra ref will be put in cgroup_free_fn() and guarantees
5140 * that @cgrp->kn is always accessible.
5144 ret
= cgroup_kn_set_ugid(kn
);
5148 ret
= css_populate_dir(&cgrp
->self
);
5152 ret
= cgroup_apply_control_enable(cgrp
);
5156 /* let's create and online css's */
5157 kernfs_activate(kn
);
5163 cgroup_destroy_locked(cgrp
);
5165 cgroup_kn_unlock(parent_kn
);
5170 * This is called when the refcnt of a css is confirmed to be killed.
5171 * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
5172 * initate destruction and put the css ref from kill_css().
5174 static void css_killed_work_fn(struct work_struct
*work
)
5176 struct cgroup_subsys_state
*css
=
5177 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
5179 mutex_lock(&cgroup_mutex
);
5184 /* @css can't go away while we're holding cgroup_mutex */
5186 } while (css
&& atomic_dec_and_test(&css
->online_cnt
));
5188 mutex_unlock(&cgroup_mutex
);
5191 /* css kill confirmation processing requires process context, bounce */
5192 static void css_killed_ref_fn(struct percpu_ref
*ref
)
5194 struct cgroup_subsys_state
*css
=
5195 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
5197 if (atomic_dec_and_test(&css
->online_cnt
)) {
5198 INIT_WORK(&css
->destroy_work
, css_killed_work_fn
);
5199 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
5204 * kill_css - destroy a css
5205 * @css: css to destroy
5207 * This function initiates destruction of @css by removing cgroup interface
5208 * files and putting its base reference. ->css_offline() will be invoked
5209 * asynchronously once css_tryget_online() is guaranteed to fail and when
5210 * the reference count reaches zero, @css will be released.
5212 static void kill_css(struct cgroup_subsys_state
*css
)
5214 lockdep_assert_held(&cgroup_mutex
);
5217 * This must happen before css is disassociated with its cgroup.
5218 * See seq_css() for details.
5223 * Killing would put the base ref, but we need to keep it alive
5224 * until after ->css_offline().
5229 * cgroup core guarantees that, by the time ->css_offline() is
5230 * invoked, no new css reference will be given out via
5231 * css_tryget_online(). We can't simply call percpu_ref_kill() and
5232 * proceed to offlining css's because percpu_ref_kill() doesn't
5233 * guarantee that the ref is seen as killed on all CPUs on return.
5235 * Use percpu_ref_kill_and_confirm() to get notifications as each
5236 * css is confirmed to be seen as killed on all CPUs.
5238 percpu_ref_kill_and_confirm(&css
->refcnt
, css_killed_ref_fn
);
5242 * cgroup_destroy_locked - the first stage of cgroup destruction
5243 * @cgrp: cgroup to be destroyed
5245 * css's make use of percpu refcnts whose killing latency shouldn't be
5246 * exposed to userland and are RCU protected. Also, cgroup core needs to
5247 * guarantee that css_tryget_online() won't succeed by the time
5248 * ->css_offline() is invoked. To satisfy all the requirements,
5249 * destruction is implemented in the following two steps.
5251 * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
5252 * userland visible parts and start killing the percpu refcnts of
5253 * css's. Set up so that the next stage will be kicked off once all
5254 * the percpu refcnts are confirmed to be killed.
5256 * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
5257 * rest of destruction. Once all cgroup references are gone, the
5258 * cgroup is RCU-freed.
5260 * This function implements s1. After this step, @cgrp is gone as far as
5261 * the userland is concerned and a new cgroup with the same name may be
5262 * created. As cgroup doesn't care about the names internally, this
5263 * doesn't cause any problem.
5265 static int cgroup_destroy_locked(struct cgroup
*cgrp
)
5266 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
5268 struct cgroup_subsys_state
*css
;
5269 struct cgrp_cset_link
*link
;
5272 lockdep_assert_held(&cgroup_mutex
);
5275 * Only migration can raise populated from zero and we're already
5276 * holding cgroup_mutex.
5278 if (cgroup_is_populated(cgrp
))
5282 * Make sure there's no live children. We can't test emptiness of
5283 * ->self.children as dead children linger on it while being
5284 * drained; otherwise, "rmdir parent/child parent" may fail.
5286 if (css_has_online_children(&cgrp
->self
))
5290 * Mark @cgrp and the associated csets dead. The former prevents
5291 * further task migration and child creation by disabling
5292 * cgroup_lock_live_group(). The latter makes the csets ignored by
5293 * the migration path.
5295 cgrp
->self
.flags
&= ~CSS_ONLINE
;
5297 spin_lock_bh(&css_set_lock
);
5298 list_for_each_entry(link
, &cgrp
->cset_links
, cset_link
)
5299 link
->cset
->dead
= true;
5300 spin_unlock_bh(&css_set_lock
);
5302 /* initiate massacre of all css's */
5303 for_each_css(css
, ssid
, cgrp
)
5307 * Remove @cgrp directory along with the base files. @cgrp has an
5308 * extra ref on its kn.
5310 kernfs_remove(cgrp
->kn
);
5312 check_for_release(cgroup_parent(cgrp
));
5314 /* put the base reference */
5315 percpu_ref_kill(&cgrp
->self
.refcnt
);
5320 static int cgroup_rmdir(struct kernfs_node
*kn
)
5322 struct cgroup
*cgrp
;
5325 cgrp
= cgroup_kn_lock_live(kn
, false);
5329 ret
= cgroup_destroy_locked(cgrp
);
5331 cgroup_kn_unlock(kn
);
5335 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
= {
5336 .remount_fs
= cgroup_remount
,
5337 .show_options
= cgroup_show_options
,
5338 .mkdir
= cgroup_mkdir
,
5339 .rmdir
= cgroup_rmdir
,
5340 .rename
= cgroup_rename
,
5343 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
, bool early
)
5345 struct cgroup_subsys_state
*css
;
5347 pr_debug("Initializing cgroup subsys %s\n", ss
->name
);
5349 mutex_lock(&cgroup_mutex
);
5351 idr_init(&ss
->css_idr
);
5352 INIT_LIST_HEAD(&ss
->cfts
);
5354 /* Create the root cgroup state for this subsystem */
5355 ss
->root
= &cgrp_dfl_root
;
5356 css
= ss
->css_alloc(cgroup_css(&cgrp_dfl_root
.cgrp
, ss
));
5357 /* We don't handle early failures gracefully */
5358 BUG_ON(IS_ERR(css
));
5359 init_and_link_css(css
, ss
, &cgrp_dfl_root
.cgrp
);
5362 * Root csses are never destroyed and we can't initialize
5363 * percpu_ref during early init. Disable refcnting.
5365 css
->flags
|= CSS_NO_REF
;
5368 /* allocation can't be done safely during early init */
5371 css
->id
= cgroup_idr_alloc(&ss
->css_idr
, css
, 1, 2, GFP_KERNEL
);
5372 BUG_ON(css
->id
< 0);
5375 /* Update the init_css_set to contain a subsys
5376 * pointer to this state - since the subsystem is
5377 * newly registered, all tasks and hence the
5378 * init_css_set is in the subsystem's root cgroup. */
5379 init_css_set
.subsys
[ss
->id
] = css
;
5381 have_fork_callback
|= (bool)ss
->fork
<< ss
->id
;
5382 have_exit_callback
|= (bool)ss
->exit
<< ss
->id
;
5383 have_free_callback
|= (bool)ss
->free
<< ss
->id
;
5384 have_canfork_callback
|= (bool)ss
->can_fork
<< ss
->id
;
5386 /* At system boot, before all subsystems have been
5387 * registered, no tasks have been forked, so we don't
5388 * need to invoke fork callbacks here. */
5389 BUG_ON(!list_empty(&init_task
.tasks
));
5391 BUG_ON(online_css(css
));
5393 mutex_unlock(&cgroup_mutex
);
5397 * cgroup_init_early - cgroup initialization at system boot
5399 * Initialize cgroups at system boot, and initialize any
5400 * subsystems that request early init.
5402 int __init
cgroup_init_early(void)
5404 static struct cgroup_sb_opts __initdata opts
;
5405 struct cgroup_subsys
*ss
;
5408 init_cgroup_root(&cgrp_dfl_root
, &opts
);
5409 cgrp_dfl_root
.cgrp
.self
.flags
|= CSS_NO_REF
;
5411 RCU_INIT_POINTER(init_task
.cgroups
, &init_css_set
);
5413 for_each_subsys(ss
, i
) {
5414 WARN(!ss
->css_alloc
|| !ss
->css_free
|| ss
->name
|| ss
->id
,
5415 "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
5416 i
, cgroup_subsys_name
[i
], ss
->css_alloc
, ss
->css_free
,
5418 WARN(strlen(cgroup_subsys_name
[i
]) > MAX_CGROUP_TYPE_NAMELEN
,
5419 "cgroup_subsys_name %s too long\n", cgroup_subsys_name
[i
]);
5422 ss
->name
= cgroup_subsys_name
[i
];
5423 if (!ss
->legacy_name
)
5424 ss
->legacy_name
= cgroup_subsys_name
[i
];
5427 cgroup_init_subsys(ss
, true);
5432 static u16 cgroup_disable_mask __initdata
;
5435 * cgroup_init - cgroup initialization
5437 * Register cgroup filesystem and /proc file, and initialize
5438 * any subsystems that didn't request early init.
5440 int __init
cgroup_init(void)
5442 struct cgroup_subsys
*ss
;
5445 BUILD_BUG_ON(CGROUP_SUBSYS_COUNT
> 16);
5446 BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem
));
5447 BUG_ON(cgroup_init_cftypes(NULL
, cgroup_dfl_base_files
));
5448 BUG_ON(cgroup_init_cftypes(NULL
, cgroup_legacy_base_files
));
5450 mutex_lock(&cgroup_mutex
);
5453 * Add init_css_set to the hash table so that dfl_root can link to
5456 hash_add(css_set_table
, &init_css_set
.hlist
,
5457 css_set_hash(init_css_set
.subsys
));
5459 BUG_ON(cgroup_setup_root(&cgrp_dfl_root
, 0));
5461 mutex_unlock(&cgroup_mutex
);
5463 for_each_subsys(ss
, ssid
) {
5464 if (ss
->early_init
) {
5465 struct cgroup_subsys_state
*css
=
5466 init_css_set
.subsys
[ss
->id
];
5468 css
->id
= cgroup_idr_alloc(&ss
->css_idr
, css
, 1, 2,
5470 BUG_ON(css
->id
< 0);
5472 cgroup_init_subsys(ss
, false);
5475 list_add_tail(&init_css_set
.e_cset_node
[ssid
],
5476 &cgrp_dfl_root
.cgrp
.e_csets
[ssid
]);
5479 * Setting dfl_root subsys_mask needs to consider the
5480 * disabled flag and cftype registration needs kmalloc,
5481 * both of which aren't available during early_init.
5483 if (cgroup_disable_mask
& (1 << ssid
)) {
5484 static_branch_disable(cgroup_subsys_enabled_key
[ssid
]);
5485 printk(KERN_INFO
"Disabling %s control group subsystem\n",
5490 if (cgroup_ssid_no_v1(ssid
))
5491 printk(KERN_INFO
"Disabling %s control group subsystem in v1 mounts\n",
5494 cgrp_dfl_root
.subsys_mask
|= 1 << ss
->id
;
5496 if (ss
->implicit_on_dfl
)
5497 cgrp_dfl_implicit_ss_mask
|= 1 << ss
->id
;
5498 else if (!ss
->dfl_cftypes
)
5499 cgrp_dfl_inhibit_ss_mask
|= 1 << ss
->id
;
5501 if (ss
->dfl_cftypes
== ss
->legacy_cftypes
) {
5502 WARN_ON(cgroup_add_cftypes(ss
, ss
->dfl_cftypes
));
5504 WARN_ON(cgroup_add_dfl_cftypes(ss
, ss
->dfl_cftypes
));
5505 WARN_ON(cgroup_add_legacy_cftypes(ss
, ss
->legacy_cftypes
));
5509 ss
->bind(init_css_set
.subsys
[ssid
]);
5512 /* init_css_set.subsys[] has been updated, re-hash */
5513 hash_del(&init_css_set
.hlist
);
5514 hash_add(css_set_table
, &init_css_set
.hlist
,
5515 css_set_hash(init_css_set
.subsys
));
5517 WARN_ON(sysfs_create_mount_point(fs_kobj
, "cgroup"));
5518 WARN_ON(register_filesystem(&cgroup_fs_type
));
5519 WARN_ON(register_filesystem(&cgroup2_fs_type
));
5520 WARN_ON(!proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
));
5525 static int __init
cgroup_wq_init(void)
5528 * There isn't much point in executing destruction path in
5529 * parallel. Good chunk is serialized with cgroup_mutex anyway.
5530 * Use 1 for @max_active.
5532 * We would prefer to do this in cgroup_init() above, but that
5533 * is called before init_workqueues(): so leave this until after.
5535 cgroup_destroy_wq
= alloc_workqueue("cgroup_destroy", 0, 1);
5536 BUG_ON(!cgroup_destroy_wq
);
5539 * Used to destroy pidlists and separate to serve as flush domain.
5540 * Cap @max_active to 1 too.
5542 cgroup_pidlist_destroy_wq
= alloc_workqueue("cgroup_pidlist_destroy",
5544 BUG_ON(!cgroup_pidlist_destroy_wq
);
5548 core_initcall(cgroup_wq_init
);
5551 * proc_cgroup_show()
5552 * - Print task's cgroup paths into seq_file, one line for each hierarchy
5553 * - Used for /proc/<pid>/cgroup.
5555 int proc_cgroup_show(struct seq_file
*m
, struct pid_namespace
*ns
,
5556 struct pid
*pid
, struct task_struct
*tsk
)
5560 struct cgroup_root
*root
;
5563 buf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
5567 mutex_lock(&cgroup_mutex
);
5568 spin_lock_bh(&css_set_lock
);
5570 for_each_root(root
) {
5571 struct cgroup_subsys
*ss
;
5572 struct cgroup
*cgrp
;
5573 int ssid
, count
= 0;
5575 if (root
== &cgrp_dfl_root
&& !cgrp_dfl_visible
)
5578 seq_printf(m
, "%d:", root
->hierarchy_id
);
5579 if (root
!= &cgrp_dfl_root
)
5580 for_each_subsys(ss
, ssid
)
5581 if (root
->subsys_mask
& (1 << ssid
))
5582 seq_printf(m
, "%s%s", count
++ ? "," : "",
5584 if (strlen(root
->name
))
5585 seq_printf(m
, "%sname=%s", count
? "," : "",
5589 cgrp
= task_cgroup_from_root(tsk
, root
);
5592 * On traditional hierarchies, all zombie tasks show up as
5593 * belonging to the root cgroup. On the default hierarchy,
5594 * while a zombie doesn't show up in "cgroup.procs" and
5595 * thus can't be migrated, its /proc/PID/cgroup keeps
5596 * reporting the cgroup it belonged to before exiting. If
5597 * the cgroup is removed before the zombie is reaped,
5598 * " (deleted)" is appended to the cgroup path.
5600 if (cgroup_on_dfl(cgrp
) || !(tsk
->flags
& PF_EXITING
)) {
5601 path
= cgroup_path(cgrp
, buf
, PATH_MAX
);
5603 retval
= -ENAMETOOLONG
;
5612 if (cgroup_on_dfl(cgrp
) && cgroup_is_dead(cgrp
))
5613 seq_puts(m
, " (deleted)\n");
5620 spin_unlock_bh(&css_set_lock
);
5621 mutex_unlock(&cgroup_mutex
);
5627 /* Display information about each subsystem and each hierarchy */
5628 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
5630 struct cgroup_subsys
*ss
;
5633 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
5635 * ideally we don't want subsystems moving around while we do this.
5636 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
5637 * subsys/hierarchy state.
5639 mutex_lock(&cgroup_mutex
);
5641 for_each_subsys(ss
, i
)
5642 seq_printf(m
, "%s\t%d\t%d\t%d\n",
5643 ss
->legacy_name
, ss
->root
->hierarchy_id
,
5644 atomic_read(&ss
->root
->nr_cgrps
),
5645 cgroup_ssid_enabled(i
));
5647 mutex_unlock(&cgroup_mutex
);
5651 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
5653 return single_open(file
, proc_cgroupstats_show
, NULL
);
5656 static const struct file_operations proc_cgroupstats_operations
= {
5657 .open
= cgroupstats_open
,
5659 .llseek
= seq_lseek
,
5660 .release
= single_release
,
5664 * cgroup_fork - initialize cgroup related fields during copy_process()
5665 * @child: pointer to task_struct of forking parent process.
5667 * A task is associated with the init_css_set until cgroup_post_fork()
5668 * attaches it to the parent's css_set. Empty cg_list indicates that
5669 * @child isn't holding reference to its css_set.
5671 void cgroup_fork(struct task_struct
*child
)
5673 RCU_INIT_POINTER(child
->cgroups
, &init_css_set
);
5674 INIT_LIST_HEAD(&child
->cg_list
);
5678 * cgroup_can_fork - called on a new task before the process is exposed
5679 * @child: the task in question.
5681 * This calls the subsystem can_fork() callbacks. If the can_fork() callback
5682 * returns an error, the fork aborts with that error code. This allows for
5683 * a cgroup subsystem to conditionally allow or deny new forks.
5685 int cgroup_can_fork(struct task_struct
*child
)
5687 struct cgroup_subsys
*ss
;
5690 do_each_subsys_mask(ss
, i
, have_canfork_callback
) {
5691 ret
= ss
->can_fork(child
);
5694 } while_each_subsys_mask();
5699 for_each_subsys(ss
, j
) {
5702 if (ss
->cancel_fork
)
5703 ss
->cancel_fork(child
);
5710 * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
5711 * @child: the task in question
5713 * This calls the cancel_fork() callbacks if a fork failed *after*
5714 * cgroup_can_fork() succeded.
5716 void cgroup_cancel_fork(struct task_struct
*child
)
5718 struct cgroup_subsys
*ss
;
5721 for_each_subsys(ss
, i
)
5722 if (ss
->cancel_fork
)
5723 ss
->cancel_fork(child
);
5727 * cgroup_post_fork - called on a new task after adding it to the task list
5728 * @child: the task in question
5730 * Adds the task to the list running through its css_set if necessary and
5731 * call the subsystem fork() callbacks. Has to be after the task is
5732 * visible on the task list in case we race with the first call to
5733 * cgroup_task_iter_start() - to guarantee that the new task ends up on its
5736 void cgroup_post_fork(struct task_struct
*child
)
5738 struct cgroup_subsys
*ss
;
5742 * This may race against cgroup_enable_task_cg_lists(). As that
5743 * function sets use_task_css_set_links before grabbing
5744 * tasklist_lock and we just went through tasklist_lock to add
5745 * @child, it's guaranteed that either we see the set
5746 * use_task_css_set_links or cgroup_enable_task_cg_lists() sees
5747 * @child during its iteration.
5749 * If we won the race, @child is associated with %current's
5750 * css_set. Grabbing css_set_lock guarantees both that the
5751 * association is stable, and, on completion of the parent's
5752 * migration, @child is visible in the source of migration or
5753 * already in the destination cgroup. This guarantee is necessary
5754 * when implementing operations which need to migrate all tasks of
5755 * a cgroup to another.
5757 * Note that if we lose to cgroup_enable_task_cg_lists(), @child
5758 * will remain in init_css_set. This is safe because all tasks are
5759 * in the init_css_set before cg_links is enabled and there's no
5760 * operation which transfers all tasks out of init_css_set.
5762 if (use_task_css_set_links
) {
5763 struct css_set
*cset
;
5765 spin_lock_bh(&css_set_lock
);
5766 cset
= task_css_set(current
);
5767 if (list_empty(&child
->cg_list
)) {
5769 css_set_move_task(child
, NULL
, cset
, false);
5771 spin_unlock_bh(&css_set_lock
);
5775 * Call ss->fork(). This must happen after @child is linked on
5776 * css_set; otherwise, @child might change state between ->fork()
5777 * and addition to css_set.
5779 do_each_subsys_mask(ss
, i
, have_fork_callback
) {
5781 } while_each_subsys_mask();
5785 * cgroup_exit - detach cgroup from exiting task
5786 * @tsk: pointer to task_struct of exiting process
5788 * Description: Detach cgroup from @tsk and release it.
5790 * Note that cgroups marked notify_on_release force every task in
5791 * them to take the global cgroup_mutex mutex when exiting.
5792 * This could impact scaling on very large systems. Be reluctant to
5793 * use notify_on_release cgroups where very high task exit scaling
5794 * is required on large systems.
5796 * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
5797 * call cgroup_exit() while the task is still competent to handle
5798 * notify_on_release(), then leave the task attached to the root cgroup in
5799 * each hierarchy for the remainder of its exit. No need to bother with
5800 * init_css_set refcnting. init_css_set never goes away and we can't race
5801 * with migration path - PF_EXITING is visible to migration path.
5803 void cgroup_exit(struct task_struct
*tsk
)
5805 struct cgroup_subsys
*ss
;
5806 struct css_set
*cset
;
5810 * Unlink from @tsk from its css_set. As migration path can't race
5811 * with us, we can check css_set and cg_list without synchronization.
5813 cset
= task_css_set(tsk
);
5815 if (!list_empty(&tsk
->cg_list
)) {
5816 spin_lock_bh(&css_set_lock
);
5817 css_set_move_task(tsk
, cset
, NULL
, false);
5818 spin_unlock_bh(&css_set_lock
);
5823 /* see cgroup_post_fork() for details */
5824 do_each_subsys_mask(ss
, i
, have_exit_callback
) {
5826 } while_each_subsys_mask();
5829 void cgroup_free(struct task_struct
*task
)
5831 struct css_set
*cset
= task_css_set(task
);
5832 struct cgroup_subsys
*ss
;
5835 do_each_subsys_mask(ss
, ssid
, have_free_callback
) {
5837 } while_each_subsys_mask();
5842 static void check_for_release(struct cgroup
*cgrp
)
5844 if (notify_on_release(cgrp
) && !cgroup_is_populated(cgrp
) &&
5845 !css_has_online_children(&cgrp
->self
) && !cgroup_is_dead(cgrp
))
5846 schedule_work(&cgrp
->release_agent_work
);
5850 * Notify userspace when a cgroup is released, by running the
5851 * configured release agent with the name of the cgroup (path
5852 * relative to the root of cgroup file system) as the argument.
5854 * Most likely, this user command will try to rmdir this cgroup.
5856 * This races with the possibility that some other task will be
5857 * attached to this cgroup before it is removed, or that some other
5858 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
5859 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
5860 * unused, and this cgroup will be reprieved from its death sentence,
5861 * to continue to serve a useful existence. Next time it's released,
5862 * we will get notified again, if it still has 'notify_on_release' set.
5864 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
5865 * means only wait until the task is successfully execve()'d. The
5866 * separate release agent task is forked by call_usermodehelper(),
5867 * then control in this thread returns here, without waiting for the
5868 * release agent task. We don't bother to wait because the caller of
5869 * this routine has no use for the exit status of the release agent
5870 * task, so no sense holding our caller up for that.
5872 static void cgroup_release_agent(struct work_struct
*work
)
5874 struct cgroup
*cgrp
=
5875 container_of(work
, struct cgroup
, release_agent_work
);
5876 char *pathbuf
= NULL
, *agentbuf
= NULL
, *path
;
5877 char *argv
[3], *envp
[3];
5879 mutex_lock(&cgroup_mutex
);
5881 pathbuf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
5882 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
5883 if (!pathbuf
|| !agentbuf
)
5886 path
= cgroup_path(cgrp
, pathbuf
, PATH_MAX
);
5894 /* minimal command environment */
5896 envp
[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
5899 mutex_unlock(&cgroup_mutex
);
5900 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
5903 mutex_unlock(&cgroup_mutex
);
5909 static int __init
cgroup_disable(char *str
)
5911 struct cgroup_subsys
*ss
;
5915 while ((token
= strsep(&str
, ",")) != NULL
) {
5919 for_each_subsys(ss
, i
) {
5920 if (strcmp(token
, ss
->name
) &&
5921 strcmp(token
, ss
->legacy_name
))
5923 cgroup_disable_mask
|= 1 << i
;
5928 __setup("cgroup_disable=", cgroup_disable
);
5930 static int __init
cgroup_no_v1(char *str
)
5932 struct cgroup_subsys
*ss
;
5936 while ((token
= strsep(&str
, ",")) != NULL
) {
5940 if (!strcmp(token
, "all")) {
5941 cgroup_no_v1_mask
= U16_MAX
;
5945 for_each_subsys(ss
, i
) {
5946 if (strcmp(token
, ss
->name
) &&
5947 strcmp(token
, ss
->legacy_name
))
5950 cgroup_no_v1_mask
|= 1 << i
;
5955 __setup("cgroup_no_v1=", cgroup_no_v1
);
5958 * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
5959 * @dentry: directory dentry of interest
5960 * @ss: subsystem of interest
5962 * If @dentry is a directory for a cgroup which has @ss enabled on it, try
5963 * to get the corresponding css and return it. If such css doesn't exist
5964 * or can't be pinned, an ERR_PTR value is returned.
5966 struct cgroup_subsys_state
*css_tryget_online_from_dir(struct dentry
*dentry
,
5967 struct cgroup_subsys
*ss
)
5969 struct kernfs_node
*kn
= kernfs_node_from_dentry(dentry
);
5970 struct file_system_type
*s_type
= dentry
->d_sb
->s_type
;
5971 struct cgroup_subsys_state
*css
= NULL
;
5972 struct cgroup
*cgrp
;
5974 /* is @dentry a cgroup dir? */
5975 if ((s_type
!= &cgroup_fs_type
&& s_type
!= &cgroup2_fs_type
) ||
5976 !kn
|| kernfs_type(kn
) != KERNFS_DIR
)
5977 return ERR_PTR(-EBADF
);
5982 * This path doesn't originate from kernfs and @kn could already
5983 * have been or be removed at any point. @kn->priv is RCU
5984 * protected for this access. See css_release_work_fn() for details.
5986 cgrp
= rcu_dereference(kn
->priv
);
5988 css
= cgroup_css(cgrp
, ss
);
5990 if (!css
|| !css_tryget_online(css
))
5991 css
= ERR_PTR(-ENOENT
);
5998 * css_from_id - lookup css by id
5999 * @id: the cgroup id
6000 * @ss: cgroup subsys to be looked into
6002 * Returns the css if there's valid one with @id, otherwise returns NULL.
6003 * Should be called under rcu_read_lock().
6005 struct cgroup_subsys_state
*css_from_id(int id
, struct cgroup_subsys
*ss
)
6007 WARN_ON_ONCE(!rcu_read_lock_held());
6008 return id
> 0 ? idr_find(&ss
->css_idr
, id
) : NULL
;
6012 * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
6013 * @path: path on the default hierarchy
6015 * Find the cgroup at @path on the default hierarchy, increment its
6016 * reference count and return it. Returns pointer to the found cgroup on
6017 * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR)
6018 * if @path points to a non-directory.
6020 struct cgroup
*cgroup_get_from_path(const char *path
)
6022 struct kernfs_node
*kn
;
6023 struct cgroup
*cgrp
;
6025 mutex_lock(&cgroup_mutex
);
6027 kn
= kernfs_walk_and_get(cgrp_dfl_root
.cgrp
.kn
, path
);
6029 if (kernfs_type(kn
) == KERNFS_DIR
) {
6033 cgrp
= ERR_PTR(-ENOTDIR
);
6037 cgrp
= ERR_PTR(-ENOENT
);
6040 mutex_unlock(&cgroup_mutex
);
6043 EXPORT_SYMBOL_GPL(cgroup_get_from_path
);
6046 * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
6047 * definition in cgroup-defs.h.
6049 #ifdef CONFIG_SOCK_CGROUP_DATA
6051 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
6053 DEFINE_SPINLOCK(cgroup_sk_update_lock
);
6054 static bool cgroup_sk_alloc_disabled __read_mostly
;
6056 void cgroup_sk_alloc_disable(void)
6058 if (cgroup_sk_alloc_disabled
)
6060 pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
6061 cgroup_sk_alloc_disabled
= true;
6066 #define cgroup_sk_alloc_disabled false
6070 void cgroup_sk_alloc(struct sock_cgroup_data
*skcd
)
6072 if (cgroup_sk_alloc_disabled
)
6078 struct css_set
*cset
;
6080 cset
= task_css_set(current
);
6081 if (likely(cgroup_tryget(cset
->dfl_cgrp
))) {
6082 skcd
->val
= (unsigned long)cset
->dfl_cgrp
;
6091 void cgroup_sk_free(struct sock_cgroup_data
*skcd
)
6093 cgroup_put(sock_cgroup_ptr(skcd
));
6096 #endif /* CONFIG_SOCK_CGROUP_DATA */
6098 #ifdef CONFIG_CGROUP_DEBUG
6099 static struct cgroup_subsys_state
*
6100 debug_css_alloc(struct cgroup_subsys_state
*parent_css
)
6102 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
6105 return ERR_PTR(-ENOMEM
);
6110 static void debug_css_free(struct cgroup_subsys_state
*css
)
6115 static u64
debug_taskcount_read(struct cgroup_subsys_state
*css
,
6118 return cgroup_task_count(css
->cgroup
);
6121 static u64
current_css_set_read(struct cgroup_subsys_state
*css
,
6124 return (u64
)(unsigned long)current
->cgroups
;
6127 static u64
current_css_set_refcount_read(struct cgroup_subsys_state
*css
,
6133 count
= atomic_read(&task_css_set(current
)->refcount
);
6138 static int current_css_set_cg_links_read(struct seq_file
*seq
, void *v
)
6140 struct cgrp_cset_link
*link
;
6141 struct css_set
*cset
;
6144 name_buf
= kmalloc(NAME_MAX
+ 1, GFP_KERNEL
);
6148 spin_lock_bh(&css_set_lock
);
6150 cset
= rcu_dereference(current
->cgroups
);
6151 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
6152 struct cgroup
*c
= link
->cgrp
;
6154 cgroup_name(c
, name_buf
, NAME_MAX
+ 1);
6155 seq_printf(seq
, "Root %d group %s\n",
6156 c
->root
->hierarchy_id
, name_buf
);
6159 spin_unlock_bh(&css_set_lock
);
6164 #define MAX_TASKS_SHOWN_PER_CSS 25
6165 static int cgroup_css_links_read(struct seq_file
*seq
, void *v
)
6167 struct cgroup_subsys_state
*css
= seq_css(seq
);
6168 struct cgrp_cset_link
*link
;
6170 spin_lock_bh(&css_set_lock
);
6171 list_for_each_entry(link
, &css
->cgroup
->cset_links
, cset_link
) {
6172 struct css_set
*cset
= link
->cset
;
6173 struct task_struct
*task
;
6176 seq_printf(seq
, "css_set %p\n", cset
);
6178 list_for_each_entry(task
, &cset
->tasks
, cg_list
) {
6179 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
)
6181 seq_printf(seq
, " task %d\n", task_pid_vnr(task
));
6184 list_for_each_entry(task
, &cset
->mg_tasks
, cg_list
) {
6185 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
)
6187 seq_printf(seq
, " task %d\n", task_pid_vnr(task
));
6191 seq_puts(seq
, " ...\n");
6193 spin_unlock_bh(&css_set_lock
);
6197 static u64
releasable_read(struct cgroup_subsys_state
*css
, struct cftype
*cft
)
6199 return (!cgroup_is_populated(css
->cgroup
) &&
6200 !css_has_online_children(&css
->cgroup
->self
));
6203 static struct cftype debug_files
[] = {
6205 .name
= "taskcount",
6206 .read_u64
= debug_taskcount_read
,
6210 .name
= "current_css_set",
6211 .read_u64
= current_css_set_read
,
6215 .name
= "current_css_set_refcount",
6216 .read_u64
= current_css_set_refcount_read
,
6220 .name
= "current_css_set_cg_links",
6221 .seq_show
= current_css_set_cg_links_read
,
6225 .name
= "cgroup_css_links",
6226 .seq_show
= cgroup_css_links_read
,
6230 .name
= "releasable",
6231 .read_u64
= releasable_read
,
6237 struct cgroup_subsys debug_cgrp_subsys
= {
6238 .css_alloc
= debug_css_alloc
,
6239 .css_free
= debug_css_free
,
6240 .legacy_cftypes
= debug_files
,
6242 #endif /* CONFIG_CGROUP_DEBUG */