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>
62 #include <linux/proc_ns.h>
63 #include <linux/nsproxy.h>
64 #include <linux/proc_ns.h>
68 * pidlists linger the following amount before being destroyed. The goal
69 * is avoiding frequent destruction in the middle of consecutive read calls
70 * Expiring in the middle is a performance problem not a correctness one.
71 * 1 sec should be enough.
73 #define CGROUP_PIDLIST_DESTROY_DELAY HZ
75 #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
79 * cgroup_mutex is the master lock. Any modification to cgroup or its
80 * hierarchy must be performed while holding it.
82 * css_set_lock protects task->cgroups pointer, the list of css_set
83 * objects, and the chain of tasks off each css_set.
85 * These locks are exported if CONFIG_PROVE_RCU so that accessors in
86 * cgroup.h can use them for lockdep annotations.
88 #ifdef CONFIG_PROVE_RCU
89 DEFINE_MUTEX(cgroup_mutex
);
90 DEFINE_SPINLOCK(css_set_lock
);
91 EXPORT_SYMBOL_GPL(cgroup_mutex
);
92 EXPORT_SYMBOL_GPL(css_set_lock
);
94 static DEFINE_MUTEX(cgroup_mutex
);
95 static DEFINE_SPINLOCK(css_set_lock
);
99 * Protects cgroup_idr and css_idr so that IDs can be released without
100 * grabbing cgroup_mutex.
102 static DEFINE_SPINLOCK(cgroup_idr_lock
);
105 * Protects cgroup_file->kn for !self csses. It synchronizes notifications
106 * against file removal/re-creation across css hiding.
108 static DEFINE_SPINLOCK(cgroup_file_kn_lock
);
111 * Protects cgroup_subsys->release_agent_path. Modifying it also requires
112 * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
114 static DEFINE_SPINLOCK(release_agent_path_lock
);
116 struct percpu_rw_semaphore cgroup_threadgroup_rwsem
;
118 #define cgroup_assert_mutex_or_rcu_locked() \
119 RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
120 !lockdep_is_held(&cgroup_mutex), \
121 "cgroup_mutex or RCU read lock required");
124 * cgroup destruction makes heavy use of work items and there can be a lot
125 * of concurrent destructions. Use a separate workqueue so that cgroup
126 * destruction work items don't end up filling up max_active of system_wq
127 * which may lead to deadlock.
129 static struct workqueue_struct
*cgroup_destroy_wq
;
132 * pidlist destructions need to be flushed on cgroup destruction. Use a
133 * separate workqueue as flush domain.
135 static struct workqueue_struct
*cgroup_pidlist_destroy_wq
;
137 /* generate an array of cgroup subsystem pointers */
138 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
139 static struct cgroup_subsys
*cgroup_subsys
[] = {
140 #include <linux/cgroup_subsys.h>
144 /* array of cgroup subsystem names */
145 #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
146 static const char *cgroup_subsys_name
[] = {
147 #include <linux/cgroup_subsys.h>
151 /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
153 DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
154 DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
155 EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
156 EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
157 #include <linux/cgroup_subsys.h>
160 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
161 static struct static_key_true
*cgroup_subsys_enabled_key
[] = {
162 #include <linux/cgroup_subsys.h>
166 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
167 static struct static_key_true
*cgroup_subsys_on_dfl_key
[] = {
168 #include <linux/cgroup_subsys.h>
173 * The default hierarchy, reserved for the subsystems that are otherwise
174 * unattached - it never has more than a single cgroup, and all tasks are
175 * part of that cgroup.
177 struct cgroup_root cgrp_dfl_root
;
178 EXPORT_SYMBOL_GPL(cgrp_dfl_root
);
181 * The default hierarchy always exists but is hidden until mounted for the
182 * first time. This is for backward compatibility.
184 static bool cgrp_dfl_visible
;
186 /* Controllers blocked by the commandline in v1 */
187 static u16 cgroup_no_v1_mask
;
189 /* some controllers are not supported in the default hierarchy */
190 static u16 cgrp_dfl_inhibit_ss_mask
;
192 /* some controllers are implicitly enabled on the default hierarchy */
193 static unsigned long cgrp_dfl_implicit_ss_mask
;
195 /* The list of hierarchy roots */
197 static LIST_HEAD(cgroup_roots
);
198 static int cgroup_root_count
;
200 /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
201 static DEFINE_IDR(cgroup_hierarchy_idr
);
204 * Assign a monotonically increasing serial number to csses. It guarantees
205 * cgroups with bigger numbers are newer than those with smaller numbers.
206 * Also, as csses are always appended to the parent's ->children list, it
207 * guarantees that sibling csses are always sorted in the ascending serial
208 * number order on the list. Protected by cgroup_mutex.
210 static u64 css_serial_nr_next
= 1;
213 * These bitmask flags indicate whether tasks in the fork and exit paths have
214 * fork/exit handlers to call. This avoids us having to do extra work in the
215 * fork/exit path to check which subsystems have fork/exit callbacks.
217 static u16 have_fork_callback __read_mostly
;
218 static u16 have_exit_callback __read_mostly
;
219 static u16 have_free_callback __read_mostly
;
221 /* cgroup namespace for init task */
222 struct cgroup_namespace init_cgroup_ns
= {
223 .count
= { .counter
= 2, },
224 .user_ns
= &init_user_ns
,
225 .ns
.ops
= &cgroupns_operations
,
226 .ns
.inum
= PROC_CGROUP_INIT_INO
,
227 .root_cset
= &init_css_set
,
230 /* Ditto for the can_fork callback. */
231 static u16 have_canfork_callback __read_mostly
;
233 static struct file_system_type cgroup2_fs_type
;
234 static struct cftype cgroup_dfl_base_files
[];
235 static struct cftype cgroup_legacy_base_files
[];
237 static int rebind_subsystems(struct cgroup_root
*dst_root
, u16 ss_mask
);
238 static void cgroup_lock_and_drain_offline(struct cgroup
*cgrp
);
239 static int cgroup_apply_control(struct cgroup
*cgrp
);
240 static void cgroup_finalize_control(struct cgroup
*cgrp
, int ret
);
241 static void css_task_iter_advance(struct css_task_iter
*it
);
242 static int cgroup_destroy_locked(struct cgroup
*cgrp
);
243 static struct cgroup_subsys_state
*css_create(struct cgroup
*cgrp
,
244 struct cgroup_subsys
*ss
);
245 static void css_release(struct percpu_ref
*ref
);
246 static void kill_css(struct cgroup_subsys_state
*css
);
247 static int cgroup_addrm_files(struct cgroup_subsys_state
*css
,
248 struct cgroup
*cgrp
, struct cftype cfts
[],
252 * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
253 * @ssid: subsys ID of interest
255 * cgroup_subsys_enabled() can only be used with literal subsys names which
256 * is fine for individual subsystems but unsuitable for cgroup core. This
257 * is slower static_key_enabled() based test indexed by @ssid.
259 static bool cgroup_ssid_enabled(int ssid
)
261 if (CGROUP_SUBSYS_COUNT
== 0)
264 return static_key_enabled(cgroup_subsys_enabled_key
[ssid
]);
267 static bool cgroup_ssid_no_v1(int ssid
)
269 return cgroup_no_v1_mask
& (1 << ssid
);
273 * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
274 * @cgrp: the cgroup of interest
276 * The default hierarchy is the v2 interface of cgroup and this function
277 * can be used to test whether a cgroup is on the default hierarchy for
278 * cases where a subsystem should behave differnetly depending on the
281 * The set of behaviors which change on the default hierarchy are still
282 * being determined and the mount option is prefixed with __DEVEL__.
284 * List of changed behaviors:
286 * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
287 * and "name" are disallowed.
289 * - When mounting an existing superblock, mount options should match.
291 * - Remount is disallowed.
293 * - rename(2) is disallowed.
295 * - "tasks" is removed. Everything should be at process granularity. Use
296 * "cgroup.procs" instead.
298 * - "cgroup.procs" is not sorted. pids will be unique unless they got
299 * recycled inbetween reads.
301 * - "release_agent" and "notify_on_release" are removed. Replacement
302 * notification mechanism will be implemented.
304 * - "cgroup.clone_children" is removed.
306 * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
307 * and its descendants contain no task; otherwise, 1. The file also
308 * generates kernfs notification which can be monitored through poll and
309 * [di]notify when the value of the file changes.
311 * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
312 * take masks of ancestors with non-empty cpus/mems, instead of being
313 * moved to an ancestor.
315 * - cpuset: a task can be moved into an empty cpuset, and again it takes
316 * masks of ancestors.
318 * - memcg: use_hierarchy is on by default and the cgroup file for the flag
321 * - blkcg: blk-throttle becomes properly hierarchical.
323 * - debug: disallowed on the default hierarchy.
325 static bool cgroup_on_dfl(const struct cgroup
*cgrp
)
327 return cgrp
->root
== &cgrp_dfl_root
;
330 /* IDR wrappers which synchronize using cgroup_idr_lock */
331 static int cgroup_idr_alloc(struct idr
*idr
, void *ptr
, int start
, int end
,
336 idr_preload(gfp_mask
);
337 spin_lock_bh(&cgroup_idr_lock
);
338 ret
= idr_alloc(idr
, ptr
, start
, end
, gfp_mask
& ~__GFP_DIRECT_RECLAIM
);
339 spin_unlock_bh(&cgroup_idr_lock
);
344 static void *cgroup_idr_replace(struct idr
*idr
, void *ptr
, int id
)
348 spin_lock_bh(&cgroup_idr_lock
);
349 ret
= idr_replace(idr
, ptr
, id
);
350 spin_unlock_bh(&cgroup_idr_lock
);
354 static void cgroup_idr_remove(struct idr
*idr
, int id
)
356 spin_lock_bh(&cgroup_idr_lock
);
358 spin_unlock_bh(&cgroup_idr_lock
);
361 static struct cgroup
*cgroup_parent(struct cgroup
*cgrp
)
363 struct cgroup_subsys_state
*parent_css
= cgrp
->self
.parent
;
366 return container_of(parent_css
, struct cgroup
, self
);
370 /* subsystems visibly enabled on a cgroup */
371 static u16
cgroup_control(struct cgroup
*cgrp
)
373 struct cgroup
*parent
= cgroup_parent(cgrp
);
374 u16 root_ss_mask
= cgrp
->root
->subsys_mask
;
377 return parent
->subtree_control
;
379 if (cgroup_on_dfl(cgrp
))
380 root_ss_mask
&= ~(cgrp_dfl_inhibit_ss_mask
|
381 cgrp_dfl_implicit_ss_mask
);
385 /* subsystems enabled on a cgroup */
386 static u16
cgroup_ss_mask(struct cgroup
*cgrp
)
388 struct cgroup
*parent
= cgroup_parent(cgrp
);
391 return parent
->subtree_ss_mask
;
393 return cgrp
->root
->subsys_mask
;
397 * cgroup_css - obtain a cgroup's css for the specified subsystem
398 * @cgrp: the cgroup of interest
399 * @ss: the subsystem of interest (%NULL returns @cgrp->self)
401 * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
402 * function must be called either under cgroup_mutex or rcu_read_lock() and
403 * the caller is responsible for pinning the returned css if it wants to
404 * keep accessing it outside the said locks. This function may return
405 * %NULL if @cgrp doesn't have @subsys_id enabled.
407 static struct cgroup_subsys_state
*cgroup_css(struct cgroup
*cgrp
,
408 struct cgroup_subsys
*ss
)
411 return rcu_dereference_check(cgrp
->subsys
[ss
->id
],
412 lockdep_is_held(&cgroup_mutex
));
418 * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
419 * @cgrp: the cgroup of interest
420 * @ss: the subsystem of interest (%NULL returns @cgrp->self)
422 * Similar to cgroup_css() but returns the effective css, which is defined
423 * as the matching css of the nearest ancestor including self which has @ss
424 * enabled. If @ss is associated with the hierarchy @cgrp is on, this
425 * function is guaranteed to return non-NULL css.
427 static struct cgroup_subsys_state
*cgroup_e_css(struct cgroup
*cgrp
,
428 struct cgroup_subsys
*ss
)
430 lockdep_assert_held(&cgroup_mutex
);
436 * This function is used while updating css associations and thus
437 * can't test the csses directly. Test ss_mask.
439 while (!(cgroup_ss_mask(cgrp
) & (1 << ss
->id
))) {
440 cgrp
= cgroup_parent(cgrp
);
445 return cgroup_css(cgrp
, ss
);
449 * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
450 * @cgrp: the cgroup of interest
451 * @ss: the subsystem of interest
453 * Find and get the effective css of @cgrp for @ss. The effective css is
454 * defined as the matching css of the nearest ancestor including self which
455 * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
456 * the root css is returned, so this function always returns a valid css.
457 * The returned css must be put using css_put().
459 struct cgroup_subsys_state
*cgroup_get_e_css(struct cgroup
*cgrp
,
460 struct cgroup_subsys
*ss
)
462 struct cgroup_subsys_state
*css
;
467 css
= cgroup_css(cgrp
, ss
);
469 if (css
&& css_tryget_online(css
))
471 cgrp
= cgroup_parent(cgrp
);
474 css
= init_css_set
.subsys
[ss
->id
];
481 /* convenient tests for these bits */
482 static inline bool cgroup_is_dead(const struct cgroup
*cgrp
)
484 return !(cgrp
->self
.flags
& CSS_ONLINE
);
487 static void cgroup_get(struct cgroup
*cgrp
)
489 WARN_ON_ONCE(cgroup_is_dead(cgrp
));
490 css_get(&cgrp
->self
);
493 static bool cgroup_tryget(struct cgroup
*cgrp
)
495 return css_tryget(&cgrp
->self
);
498 struct cgroup_subsys_state
*of_css(struct kernfs_open_file
*of
)
500 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
501 struct cftype
*cft
= of_cft(of
);
504 * This is open and unprotected implementation of cgroup_css().
505 * seq_css() is only called from a kernfs file operation which has
506 * an active reference on the file. Because all the subsystem
507 * files are drained before a css is disassociated with a cgroup,
508 * the matching css from the cgroup's subsys table is guaranteed to
509 * be and stay valid until the enclosing operation is complete.
512 return rcu_dereference_raw(cgrp
->subsys
[cft
->ss
->id
]);
516 EXPORT_SYMBOL_GPL(of_css
);
518 static int notify_on_release(const struct cgroup
*cgrp
)
520 return test_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
524 * for_each_css - iterate all 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_css(css, ssid, cgrp) \
532 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
533 if (!((css) = rcu_dereference_check( \
534 (cgrp)->subsys[(ssid)], \
535 lockdep_is_held(&cgroup_mutex)))) { } \
539 * for_each_e_css - iterate all effective css's of a cgroup
540 * @css: the iteration cursor
541 * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
542 * @cgrp: the target cgroup to iterate css's of
544 * Should be called under cgroup_[tree_]mutex.
546 #define for_each_e_css(css, ssid, cgrp) \
547 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
548 if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
553 * for_each_subsys - iterate all enabled cgroup subsystems
554 * @ss: the iteration cursor
555 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
557 #define for_each_subsys(ss, ssid) \
558 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
559 (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
562 * do_each_subsys_mask - filter for_each_subsys with a bitmask
563 * @ss: the iteration cursor
564 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
565 * @ss_mask: the bitmask
567 * The block will only run for cases where the ssid-th bit (1 << ssid) of
570 #define do_each_subsys_mask(ss, ssid, ss_mask) do { \
571 unsigned long __ss_mask = (ss_mask); \
572 if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
576 for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
577 (ss) = cgroup_subsys[ssid]; \
580 #define while_each_subsys_mask() \
585 /* iterate across the hierarchies */
586 #define for_each_root(root) \
587 list_for_each_entry((root), &cgroup_roots, root_list)
589 /* iterate over child cgrps, lock should be held throughout iteration */
590 #define cgroup_for_each_live_child(child, cgrp) \
591 list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
592 if (({ lockdep_assert_held(&cgroup_mutex); \
593 cgroup_is_dead(child); })) \
597 /* walk live descendants in preorder */
598 #define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
599 css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
600 if (({ lockdep_assert_held(&cgroup_mutex); \
601 (dsct) = (d_css)->cgroup; \
602 cgroup_is_dead(dsct); })) \
606 /* walk live descendants in postorder */
607 #define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
608 css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
609 if (({ lockdep_assert_held(&cgroup_mutex); \
610 (dsct) = (d_css)->cgroup; \
611 cgroup_is_dead(dsct); })) \
615 static void cgroup_release_agent(struct work_struct
*work
);
616 static void check_for_release(struct cgroup
*cgrp
);
619 * A cgroup can be associated with multiple css_sets as different tasks may
620 * belong to different cgroups on different hierarchies. In the other
621 * direction, a css_set is naturally associated with multiple cgroups.
622 * This M:N relationship is represented by the following link structure
623 * which exists for each association and allows traversing the associations
626 struct cgrp_cset_link
{
627 /* the cgroup and css_set this link associates */
629 struct css_set
*cset
;
631 /* list of cgrp_cset_links anchored at cgrp->cset_links */
632 struct list_head cset_link
;
634 /* list of cgrp_cset_links anchored at css_set->cgrp_links */
635 struct list_head cgrp_link
;
639 * The default css_set - used by init and its children prior to any
640 * hierarchies being mounted. It contains a pointer to the root state
641 * for each subsystem. Also used to anchor the list of css_sets. Not
642 * reference-counted, to improve performance when child cgroups
643 * haven't been created.
645 struct css_set init_css_set
= {
646 .refcount
= ATOMIC_INIT(1),
647 .cgrp_links
= LIST_HEAD_INIT(init_css_set
.cgrp_links
),
648 .tasks
= LIST_HEAD_INIT(init_css_set
.tasks
),
649 .mg_tasks
= LIST_HEAD_INIT(init_css_set
.mg_tasks
),
650 .mg_preload_node
= LIST_HEAD_INIT(init_css_set
.mg_preload_node
),
651 .mg_node
= LIST_HEAD_INIT(init_css_set
.mg_node
),
652 .task_iters
= LIST_HEAD_INIT(init_css_set
.task_iters
),
655 static int css_set_count
= 1; /* 1 for init_css_set */
658 * css_set_populated - does a css_set contain any tasks?
659 * @cset: target css_set
661 static bool css_set_populated(struct css_set
*cset
)
663 lockdep_assert_held(&css_set_lock
);
665 return !list_empty(&cset
->tasks
) || !list_empty(&cset
->mg_tasks
);
669 * cgroup_update_populated - updated populated count of a cgroup
670 * @cgrp: the target cgroup
671 * @populated: inc or dec populated count
673 * One of the css_sets associated with @cgrp is either getting its first
674 * task or losing the last. Update @cgrp->populated_cnt accordingly. The
675 * count is propagated towards root so that a given cgroup's populated_cnt
676 * is zero iff the cgroup and all its descendants don't contain any tasks.
678 * @cgrp's interface file "cgroup.populated" is zero if
679 * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
680 * changes from or to zero, userland is notified that the content of the
681 * interface file has changed. This can be used to detect when @cgrp and
682 * its descendants become populated or empty.
684 static void cgroup_update_populated(struct cgroup
*cgrp
, bool populated
)
686 lockdep_assert_held(&css_set_lock
);
692 trigger
= !cgrp
->populated_cnt
++;
694 trigger
= !--cgrp
->populated_cnt
;
699 check_for_release(cgrp
);
700 cgroup_file_notify(&cgrp
->events_file
);
702 cgrp
= cgroup_parent(cgrp
);
707 * css_set_update_populated - update populated state of a css_set
708 * @cset: target css_set
709 * @populated: whether @cset is populated or depopulated
711 * @cset is either getting the first task or losing the last. Update the
712 * ->populated_cnt of all associated cgroups accordingly.
714 static void css_set_update_populated(struct css_set
*cset
, bool populated
)
716 struct cgrp_cset_link
*link
;
718 lockdep_assert_held(&css_set_lock
);
720 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
)
721 cgroup_update_populated(link
->cgrp
, populated
);
725 * css_set_move_task - move a task from one css_set to another
726 * @task: task being moved
727 * @from_cset: css_set @task currently belongs to (may be NULL)
728 * @to_cset: new css_set @task is being moved to (may be NULL)
729 * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
731 * Move @task from @from_cset to @to_cset. If @task didn't belong to any
732 * css_set, @from_cset can be NULL. If @task is being disassociated
733 * instead of moved, @to_cset can be NULL.
735 * This function automatically handles populated_cnt updates and
736 * css_task_iter adjustments but the caller is responsible for managing
737 * @from_cset and @to_cset's reference counts.
739 static void css_set_move_task(struct task_struct
*task
,
740 struct css_set
*from_cset
, struct css_set
*to_cset
,
743 lockdep_assert_held(&css_set_lock
);
745 if (to_cset
&& !css_set_populated(to_cset
))
746 css_set_update_populated(to_cset
, true);
749 struct css_task_iter
*it
, *pos
;
751 WARN_ON_ONCE(list_empty(&task
->cg_list
));
754 * @task is leaving, advance task iterators which are
755 * pointing to it so that they can resume at the next
756 * position. Advancing an iterator might remove it from
757 * the list, use safe walk. See css_task_iter_advance*()
760 list_for_each_entry_safe(it
, pos
, &from_cset
->task_iters
,
762 if (it
->task_pos
== &task
->cg_list
)
763 css_task_iter_advance(it
);
765 list_del_init(&task
->cg_list
);
766 if (!css_set_populated(from_cset
))
767 css_set_update_populated(from_cset
, false);
769 WARN_ON_ONCE(!list_empty(&task
->cg_list
));
774 * We are synchronized through cgroup_threadgroup_rwsem
775 * against PF_EXITING setting such that we can't race
776 * against cgroup_exit() changing the css_set to
777 * init_css_set and dropping the old one.
779 WARN_ON_ONCE(task
->flags
& PF_EXITING
);
781 rcu_assign_pointer(task
->cgroups
, to_cset
);
782 list_add_tail(&task
->cg_list
, use_mg_tasks
? &to_cset
->mg_tasks
:
788 * hash table for cgroup groups. This improves the performance to find
789 * an existing css_set. This hash doesn't (currently) take into
790 * account cgroups in empty hierarchies.
792 #define CSS_SET_HASH_BITS 7
793 static DEFINE_HASHTABLE(css_set_table
, CSS_SET_HASH_BITS
);
795 static unsigned long css_set_hash(struct cgroup_subsys_state
*css
[])
797 unsigned long key
= 0UL;
798 struct cgroup_subsys
*ss
;
801 for_each_subsys(ss
, i
)
802 key
+= (unsigned long)css
[i
];
803 key
= (key
>> 16) ^ key
;
808 static void put_css_set_locked(struct css_set
*cset
)
810 struct cgrp_cset_link
*link
, *tmp_link
;
811 struct cgroup_subsys
*ss
;
814 lockdep_assert_held(&css_set_lock
);
816 if (!atomic_dec_and_test(&cset
->refcount
))
819 /* This css_set is dead. unlink it and release cgroup and css refs */
820 for_each_subsys(ss
, ssid
) {
821 list_del(&cset
->e_cset_node
[ssid
]);
822 css_put(cset
->subsys
[ssid
]);
824 hash_del(&cset
->hlist
);
827 list_for_each_entry_safe(link
, tmp_link
, &cset
->cgrp_links
, cgrp_link
) {
828 list_del(&link
->cset_link
);
829 list_del(&link
->cgrp_link
);
830 if (cgroup_parent(link
->cgrp
))
831 cgroup_put(link
->cgrp
);
835 kfree_rcu(cset
, rcu_head
);
838 static void put_css_set(struct css_set
*cset
)
843 * Ensure that the refcount doesn't hit zero while any readers
844 * can see it. Similar to atomic_dec_and_lock(), but for an
847 if (atomic_add_unless(&cset
->refcount
, -1, 1))
850 spin_lock_irqsave(&css_set_lock
, flags
);
851 put_css_set_locked(cset
);
852 spin_unlock_irqrestore(&css_set_lock
, flags
);
856 * refcounted get/put for css_set objects
858 static inline void get_css_set(struct css_set
*cset
)
860 atomic_inc(&cset
->refcount
);
864 * compare_css_sets - helper function for find_existing_css_set().
865 * @cset: candidate css_set being tested
866 * @old_cset: existing css_set for a task
867 * @new_cgrp: cgroup that's being entered by the task
868 * @template: desired set of css pointers in css_set (pre-calculated)
870 * Returns true if "cset" matches "old_cset" except for the hierarchy
871 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
873 static bool compare_css_sets(struct css_set
*cset
,
874 struct css_set
*old_cset
,
875 struct cgroup
*new_cgrp
,
876 struct cgroup_subsys_state
*template[])
878 struct list_head
*l1
, *l2
;
881 * On the default hierarchy, there can be csets which are
882 * associated with the same set of cgroups but different csses.
883 * Let's first ensure that csses match.
885 if (memcmp(template, cset
->subsys
, sizeof(cset
->subsys
)))
889 * Compare cgroup pointers in order to distinguish between
890 * different cgroups in hierarchies. As different cgroups may
891 * share the same effective css, this comparison is always
894 l1
= &cset
->cgrp_links
;
895 l2
= &old_cset
->cgrp_links
;
897 struct cgrp_cset_link
*link1
, *link2
;
898 struct cgroup
*cgrp1
, *cgrp2
;
902 /* See if we reached the end - both lists are equal length. */
903 if (l1
== &cset
->cgrp_links
) {
904 BUG_ON(l2
!= &old_cset
->cgrp_links
);
907 BUG_ON(l2
== &old_cset
->cgrp_links
);
909 /* Locate the cgroups associated with these links. */
910 link1
= list_entry(l1
, struct cgrp_cset_link
, cgrp_link
);
911 link2
= list_entry(l2
, struct cgrp_cset_link
, cgrp_link
);
914 /* Hierarchies should be linked in the same order. */
915 BUG_ON(cgrp1
->root
!= cgrp2
->root
);
918 * If this hierarchy is the hierarchy of the cgroup
919 * that's changing, then we need to check that this
920 * css_set points to the new cgroup; if it's any other
921 * hierarchy, then this css_set should point to the
922 * same cgroup as the old css_set.
924 if (cgrp1
->root
== new_cgrp
->root
) {
925 if (cgrp1
!= new_cgrp
)
936 * find_existing_css_set - init css array and find the matching css_set
937 * @old_cset: the css_set that we're using before the cgroup transition
938 * @cgrp: the cgroup that we're moving into
939 * @template: out param for the new set of csses, should be clear on entry
941 static struct css_set
*find_existing_css_set(struct css_set
*old_cset
,
943 struct cgroup_subsys_state
*template[])
945 struct cgroup_root
*root
= cgrp
->root
;
946 struct cgroup_subsys
*ss
;
947 struct css_set
*cset
;
952 * Build the set of subsystem state objects that we want to see in the
953 * new css_set. while subsystems can change globally, the entries here
954 * won't change, so no need for locking.
956 for_each_subsys(ss
, i
) {
957 if (root
->subsys_mask
& (1UL << i
)) {
959 * @ss is in this hierarchy, so we want the
960 * effective css from @cgrp.
962 template[i
] = cgroup_e_css(cgrp
, ss
);
965 * @ss is not in this hierarchy, so we don't want
968 template[i
] = old_cset
->subsys
[i
];
972 key
= css_set_hash(template);
973 hash_for_each_possible(css_set_table
, cset
, hlist
, key
) {
974 if (!compare_css_sets(cset
, old_cset
, cgrp
, template))
977 /* This css_set matches what we need */
981 /* No existing cgroup group matched */
985 static void free_cgrp_cset_links(struct list_head
*links_to_free
)
987 struct cgrp_cset_link
*link
, *tmp_link
;
989 list_for_each_entry_safe(link
, tmp_link
, links_to_free
, cset_link
) {
990 list_del(&link
->cset_link
);
996 * allocate_cgrp_cset_links - allocate cgrp_cset_links
997 * @count: the number of links to allocate
998 * @tmp_links: list_head the allocated links are put on
1000 * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
1001 * through ->cset_link. Returns 0 on success or -errno.
1003 static int allocate_cgrp_cset_links(int count
, struct list_head
*tmp_links
)
1005 struct cgrp_cset_link
*link
;
1008 INIT_LIST_HEAD(tmp_links
);
1010 for (i
= 0; i
< count
; i
++) {
1011 link
= kzalloc(sizeof(*link
), GFP_KERNEL
);
1013 free_cgrp_cset_links(tmp_links
);
1016 list_add(&link
->cset_link
, tmp_links
);
1022 * link_css_set - a helper function to link a css_set to a cgroup
1023 * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
1024 * @cset: the css_set to be linked
1025 * @cgrp: the destination cgroup
1027 static void link_css_set(struct list_head
*tmp_links
, struct css_set
*cset
,
1028 struct cgroup
*cgrp
)
1030 struct cgrp_cset_link
*link
;
1032 BUG_ON(list_empty(tmp_links
));
1034 if (cgroup_on_dfl(cgrp
))
1035 cset
->dfl_cgrp
= cgrp
;
1037 link
= list_first_entry(tmp_links
, struct cgrp_cset_link
, cset_link
);
1042 * Always add links to the tail of the lists so that the lists are
1043 * in choronological order.
1045 list_move_tail(&link
->cset_link
, &cgrp
->cset_links
);
1046 list_add_tail(&link
->cgrp_link
, &cset
->cgrp_links
);
1048 if (cgroup_parent(cgrp
))
1053 * find_css_set - return a new css_set with one cgroup updated
1054 * @old_cset: the baseline css_set
1055 * @cgrp: the cgroup to be updated
1057 * Return a new css_set that's equivalent to @old_cset, but with @cgrp
1058 * substituted into the appropriate hierarchy.
1060 static struct css_set
*find_css_set(struct css_set
*old_cset
,
1061 struct cgroup
*cgrp
)
1063 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
] = { };
1064 struct css_set
*cset
;
1065 struct list_head tmp_links
;
1066 struct cgrp_cset_link
*link
;
1067 struct cgroup_subsys
*ss
;
1071 lockdep_assert_held(&cgroup_mutex
);
1073 /* First see if we already have a cgroup group that matches
1074 * the desired set */
1075 spin_lock_irq(&css_set_lock
);
1076 cset
= find_existing_css_set(old_cset
, cgrp
, template);
1079 spin_unlock_irq(&css_set_lock
);
1084 cset
= kzalloc(sizeof(*cset
), GFP_KERNEL
);
1088 /* Allocate all the cgrp_cset_link objects that we'll need */
1089 if (allocate_cgrp_cset_links(cgroup_root_count
, &tmp_links
) < 0) {
1094 atomic_set(&cset
->refcount
, 1);
1095 INIT_LIST_HEAD(&cset
->cgrp_links
);
1096 INIT_LIST_HEAD(&cset
->tasks
);
1097 INIT_LIST_HEAD(&cset
->mg_tasks
);
1098 INIT_LIST_HEAD(&cset
->mg_preload_node
);
1099 INIT_LIST_HEAD(&cset
->mg_node
);
1100 INIT_LIST_HEAD(&cset
->task_iters
);
1101 INIT_HLIST_NODE(&cset
->hlist
);
1103 /* Copy the set of subsystem state objects generated in
1104 * find_existing_css_set() */
1105 memcpy(cset
->subsys
, template, sizeof(cset
->subsys
));
1107 spin_lock_irq(&css_set_lock
);
1108 /* Add reference counts and links from the new css_set. */
1109 list_for_each_entry(link
, &old_cset
->cgrp_links
, cgrp_link
) {
1110 struct cgroup
*c
= link
->cgrp
;
1112 if (c
->root
== cgrp
->root
)
1114 link_css_set(&tmp_links
, cset
, c
);
1117 BUG_ON(!list_empty(&tmp_links
));
1121 /* Add @cset to the hash table */
1122 key
= css_set_hash(cset
->subsys
);
1123 hash_add(css_set_table
, &cset
->hlist
, key
);
1125 for_each_subsys(ss
, ssid
) {
1126 struct cgroup_subsys_state
*css
= cset
->subsys
[ssid
];
1128 list_add_tail(&cset
->e_cset_node
[ssid
],
1129 &css
->cgroup
->e_csets
[ssid
]);
1133 spin_unlock_irq(&css_set_lock
);
1138 static struct cgroup_root
*cgroup_root_from_kf(struct kernfs_root
*kf_root
)
1140 struct cgroup
*root_cgrp
= kf_root
->kn
->priv
;
1142 return root_cgrp
->root
;
1145 static int cgroup_init_root_id(struct cgroup_root
*root
)
1149 lockdep_assert_held(&cgroup_mutex
);
1151 id
= idr_alloc_cyclic(&cgroup_hierarchy_idr
, root
, 0, 0, GFP_KERNEL
);
1155 root
->hierarchy_id
= id
;
1159 static void cgroup_exit_root_id(struct cgroup_root
*root
)
1161 lockdep_assert_held(&cgroup_mutex
);
1163 if (root
->hierarchy_id
) {
1164 idr_remove(&cgroup_hierarchy_idr
, root
->hierarchy_id
);
1165 root
->hierarchy_id
= 0;
1169 static void cgroup_free_root(struct cgroup_root
*root
)
1172 /* hierarchy ID should already have been released */
1173 WARN_ON_ONCE(root
->hierarchy_id
);
1175 idr_destroy(&root
->cgroup_idr
);
1180 static void cgroup_destroy_root(struct cgroup_root
*root
)
1182 struct cgroup
*cgrp
= &root
->cgrp
;
1183 struct cgrp_cset_link
*link
, *tmp_link
;
1185 cgroup_lock_and_drain_offline(&cgrp_dfl_root
.cgrp
);
1187 BUG_ON(atomic_read(&root
->nr_cgrps
));
1188 BUG_ON(!list_empty(&cgrp
->self
.children
));
1190 /* Rebind all subsystems back to the default hierarchy */
1191 WARN_ON(rebind_subsystems(&cgrp_dfl_root
, root
->subsys_mask
));
1194 * Release all the links from cset_links to this hierarchy's
1197 spin_lock_irq(&css_set_lock
);
1199 list_for_each_entry_safe(link
, tmp_link
, &cgrp
->cset_links
, cset_link
) {
1200 list_del(&link
->cset_link
);
1201 list_del(&link
->cgrp_link
);
1205 spin_unlock_irq(&css_set_lock
);
1207 if (!list_empty(&root
->root_list
)) {
1208 list_del(&root
->root_list
);
1209 cgroup_root_count
--;
1212 cgroup_exit_root_id(root
);
1214 mutex_unlock(&cgroup_mutex
);
1216 kernfs_destroy_root(root
->kf_root
);
1217 cgroup_free_root(root
);
1221 * look up cgroup associated with current task's cgroup namespace on the
1222 * specified hierarchy
1224 static struct cgroup
*
1225 current_cgns_cgroup_from_root(struct cgroup_root
*root
)
1227 struct cgroup
*res
= NULL
;
1228 struct css_set
*cset
;
1230 lockdep_assert_held(&css_set_lock
);
1234 cset
= current
->nsproxy
->cgroup_ns
->root_cset
;
1235 if (cset
== &init_css_set
) {
1238 struct cgrp_cset_link
*link
;
1240 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
1241 struct cgroup
*c
= link
->cgrp
;
1243 if (c
->root
== root
) {
1255 /* look up cgroup associated with given css_set on the specified hierarchy */
1256 static struct cgroup
*cset_cgroup_from_root(struct css_set
*cset
,
1257 struct cgroup_root
*root
)
1259 struct cgroup
*res
= NULL
;
1261 lockdep_assert_held(&cgroup_mutex
);
1262 lockdep_assert_held(&css_set_lock
);
1264 if (cset
== &init_css_set
) {
1267 struct cgrp_cset_link
*link
;
1269 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
1270 struct cgroup
*c
= link
->cgrp
;
1272 if (c
->root
== root
) {
1284 * Return the cgroup for "task" from the given hierarchy. Must be
1285 * called with cgroup_mutex and css_set_lock held.
1287 static struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
1288 struct cgroup_root
*root
)
1291 * No need to lock the task - since we hold cgroup_mutex the
1292 * task can't change groups, so the only thing that can happen
1293 * is that it exits and its css is set back to init_css_set.
1295 return cset_cgroup_from_root(task_css_set(task
), root
);
1299 * A task must hold cgroup_mutex to modify cgroups.
1301 * Any task can increment and decrement the count field without lock.
1302 * So in general, code holding cgroup_mutex can't rely on the count
1303 * field not changing. However, if the count goes to zero, then only
1304 * cgroup_attach_task() can increment it again. Because a count of zero
1305 * means that no tasks are currently attached, therefore there is no
1306 * way a task attached to that cgroup can fork (the other way to
1307 * increment the count). So code holding cgroup_mutex can safely
1308 * assume that if the count is zero, it will stay zero. Similarly, if
1309 * a task holds cgroup_mutex on a cgroup with zero count, it
1310 * knows that the cgroup won't be removed, as cgroup_rmdir()
1313 * A cgroup can only be deleted if both its 'count' of using tasks
1314 * is zero, and its list of 'children' cgroups is empty. Since all
1315 * tasks in the system use _some_ cgroup, and since there is always at
1316 * least one task in the system (init, pid == 1), therefore, root cgroup
1317 * always has either children cgroups and/or using tasks. So we don't
1318 * need a special hack to ensure that root cgroup cannot be deleted.
1320 * P.S. One more locking exception. RCU is used to guard the
1321 * update of a tasks cgroup pointer by cgroup_attach_task()
1324 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
;
1325 static const struct file_operations proc_cgroupstats_operations
;
1327 static char *cgroup_file_name(struct cgroup
*cgrp
, const struct cftype
*cft
,
1330 struct cgroup_subsys
*ss
= cft
->ss
;
1332 if (cft
->ss
&& !(cft
->flags
& CFTYPE_NO_PREFIX
) &&
1333 !(cgrp
->root
->flags
& CGRP_ROOT_NOPREFIX
))
1334 snprintf(buf
, CGROUP_FILE_NAME_MAX
, "%s.%s",
1335 cgroup_on_dfl(cgrp
) ? ss
->name
: ss
->legacy_name
,
1338 strncpy(buf
, cft
->name
, CGROUP_FILE_NAME_MAX
);
1343 * cgroup_file_mode - deduce file mode of a control file
1344 * @cft: the control file in question
1346 * S_IRUGO for read, S_IWUSR for write.
1348 static umode_t
cgroup_file_mode(const struct cftype
*cft
)
1352 if (cft
->read_u64
|| cft
->read_s64
|| cft
->seq_show
)
1355 if (cft
->write_u64
|| cft
->write_s64
|| cft
->write
) {
1356 if (cft
->flags
& CFTYPE_WORLD_WRITABLE
)
1366 * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
1367 * @subtree_control: the new subtree_control mask to consider
1368 * @this_ss_mask: available subsystems
1370 * On the default hierarchy, a subsystem may request other subsystems to be
1371 * enabled together through its ->depends_on mask. In such cases, more
1372 * subsystems than specified in "cgroup.subtree_control" may be enabled.
1374 * This function calculates which subsystems need to be enabled if
1375 * @subtree_control is to be applied while restricted to @this_ss_mask.
1377 static u16
cgroup_calc_subtree_ss_mask(u16 subtree_control
, u16 this_ss_mask
)
1379 u16 cur_ss_mask
= subtree_control
;
1380 struct cgroup_subsys
*ss
;
1383 lockdep_assert_held(&cgroup_mutex
);
1385 cur_ss_mask
|= cgrp_dfl_implicit_ss_mask
;
1388 u16 new_ss_mask
= cur_ss_mask
;
1390 do_each_subsys_mask(ss
, ssid
, cur_ss_mask
) {
1391 new_ss_mask
|= ss
->depends_on
;
1392 } while_each_subsys_mask();
1395 * Mask out subsystems which aren't available. This can
1396 * happen only if some depended-upon subsystems were bound
1397 * to non-default hierarchies.
1399 new_ss_mask
&= this_ss_mask
;
1401 if (new_ss_mask
== cur_ss_mask
)
1403 cur_ss_mask
= new_ss_mask
;
1410 * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
1411 * @kn: the kernfs_node being serviced
1413 * This helper undoes cgroup_kn_lock_live() and should be invoked before
1414 * the method finishes if locking succeeded. Note that once this function
1415 * returns the cgroup returned by cgroup_kn_lock_live() may become
1416 * inaccessible any time. If the caller intends to continue to access the
1417 * cgroup, it should pin it before invoking this function.
1419 static void cgroup_kn_unlock(struct kernfs_node
*kn
)
1421 struct cgroup
*cgrp
;
1423 if (kernfs_type(kn
) == KERNFS_DIR
)
1426 cgrp
= kn
->parent
->priv
;
1428 mutex_unlock(&cgroup_mutex
);
1430 kernfs_unbreak_active_protection(kn
);
1435 * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
1436 * @kn: the kernfs_node being serviced
1437 * @drain_offline: perform offline draining on the cgroup
1439 * This helper is to be used by a cgroup kernfs method currently servicing
1440 * @kn. It breaks the active protection, performs cgroup locking and
1441 * verifies that the associated cgroup is alive. Returns the cgroup if
1442 * alive; otherwise, %NULL. A successful return should be undone by a
1443 * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
1444 * cgroup is drained of offlining csses before return.
1446 * Any cgroup kernfs method implementation which requires locking the
1447 * associated cgroup should use this helper. It avoids nesting cgroup
1448 * locking under kernfs active protection and allows all kernfs operations
1449 * including self-removal.
1451 static struct cgroup
*cgroup_kn_lock_live(struct kernfs_node
*kn
,
1454 struct cgroup
*cgrp
;
1456 if (kernfs_type(kn
) == KERNFS_DIR
)
1459 cgrp
= kn
->parent
->priv
;
1462 * We're gonna grab cgroup_mutex which nests outside kernfs
1463 * active_ref. cgroup liveliness check alone provides enough
1464 * protection against removal. Ensure @cgrp stays accessible and
1465 * break the active_ref protection.
1467 if (!cgroup_tryget(cgrp
))
1469 kernfs_break_active_protection(kn
);
1472 cgroup_lock_and_drain_offline(cgrp
);
1474 mutex_lock(&cgroup_mutex
);
1476 if (!cgroup_is_dead(cgrp
))
1479 cgroup_kn_unlock(kn
);
1483 static void cgroup_rm_file(struct cgroup
*cgrp
, const struct cftype
*cft
)
1485 char name
[CGROUP_FILE_NAME_MAX
];
1487 lockdep_assert_held(&cgroup_mutex
);
1489 if (cft
->file_offset
) {
1490 struct cgroup_subsys_state
*css
= cgroup_css(cgrp
, cft
->ss
);
1491 struct cgroup_file
*cfile
= (void *)css
+ cft
->file_offset
;
1493 spin_lock_irq(&cgroup_file_kn_lock
);
1495 spin_unlock_irq(&cgroup_file_kn_lock
);
1498 kernfs_remove_by_name(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
));
1502 * css_clear_dir - remove subsys files in a cgroup directory
1505 static void css_clear_dir(struct cgroup_subsys_state
*css
)
1507 struct cgroup
*cgrp
= css
->cgroup
;
1508 struct cftype
*cfts
;
1510 if (!(css
->flags
& CSS_VISIBLE
))
1513 css
->flags
&= ~CSS_VISIBLE
;
1515 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
)
1516 cgroup_addrm_files(css
, cgrp
, cfts
, false);
1520 * css_populate_dir - create subsys files in a cgroup directory
1523 * On failure, no file is added.
1525 static int css_populate_dir(struct cgroup_subsys_state
*css
)
1527 struct cgroup
*cgrp
= css
->cgroup
;
1528 struct cftype
*cfts
, *failed_cfts
;
1531 if ((css
->flags
& CSS_VISIBLE
) || !cgrp
->kn
)
1535 if (cgroup_on_dfl(cgrp
))
1536 cfts
= cgroup_dfl_base_files
;
1538 cfts
= cgroup_legacy_base_files
;
1540 return cgroup_addrm_files(&cgrp
->self
, cgrp
, cfts
, true);
1543 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
) {
1544 ret
= cgroup_addrm_files(css
, cgrp
, cfts
, true);
1551 css
->flags
|= CSS_VISIBLE
;
1555 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
) {
1556 if (cfts
== failed_cfts
)
1558 cgroup_addrm_files(css
, cgrp
, cfts
, false);
1563 static int rebind_subsystems(struct cgroup_root
*dst_root
, u16 ss_mask
)
1565 struct cgroup
*dcgrp
= &dst_root
->cgrp
;
1566 struct cgroup_subsys
*ss
;
1569 lockdep_assert_held(&cgroup_mutex
);
1571 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
1573 * If @ss has non-root csses attached to it, can't move.
1574 * If @ss is an implicit controller, it is exempt from this
1575 * rule and can be stolen.
1577 if (css_next_child(NULL
, cgroup_css(&ss
->root
->cgrp
, ss
)) &&
1578 !ss
->implicit_on_dfl
)
1581 /* can't move between two non-dummy roots either */
1582 if (ss
->root
!= &cgrp_dfl_root
&& dst_root
!= &cgrp_dfl_root
)
1584 } while_each_subsys_mask();
1586 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
1587 struct cgroup_root
*src_root
= ss
->root
;
1588 struct cgroup
*scgrp
= &src_root
->cgrp
;
1589 struct cgroup_subsys_state
*css
= cgroup_css(scgrp
, ss
);
1590 struct css_set
*cset
;
1592 WARN_ON(!css
|| cgroup_css(dcgrp
, ss
));
1594 /* disable from the source */
1595 src_root
->subsys_mask
&= ~(1 << ssid
);
1596 WARN_ON(cgroup_apply_control(scgrp
));
1597 cgroup_finalize_control(scgrp
, 0);
1600 RCU_INIT_POINTER(scgrp
->subsys
[ssid
], NULL
);
1601 rcu_assign_pointer(dcgrp
->subsys
[ssid
], css
);
1602 ss
->root
= dst_root
;
1603 css
->cgroup
= dcgrp
;
1605 spin_lock_irq(&css_set_lock
);
1606 hash_for_each(css_set_table
, i
, cset
, hlist
)
1607 list_move_tail(&cset
->e_cset_node
[ss
->id
],
1608 &dcgrp
->e_csets
[ss
->id
]);
1609 spin_unlock_irq(&css_set_lock
);
1611 /* default hierarchy doesn't enable controllers by default */
1612 dst_root
->subsys_mask
|= 1 << ssid
;
1613 if (dst_root
== &cgrp_dfl_root
) {
1614 static_branch_enable(cgroup_subsys_on_dfl_key
[ssid
]);
1616 dcgrp
->subtree_control
|= 1 << ssid
;
1617 static_branch_disable(cgroup_subsys_on_dfl_key
[ssid
]);
1620 ret
= cgroup_apply_control(dcgrp
);
1622 pr_warn("partial failure to rebind %s controller (err=%d)\n",
1627 } while_each_subsys_mask();
1629 kernfs_activate(dcgrp
->kn
);
1633 static int cgroup_show_path(struct seq_file
*sf
, struct kernfs_node
*kf_node
,
1634 struct kernfs_root
*kf_root
)
1638 struct cgroup_root
*kf_cgroot
= cgroup_root_from_kf(kf_root
);
1639 struct cgroup
*ns_cgroup
;
1641 buf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
1645 spin_lock_irq(&css_set_lock
);
1646 ns_cgroup
= current_cgns_cgroup_from_root(kf_cgroot
);
1647 len
= kernfs_path_from_node(kf_node
, ns_cgroup
->kn
, buf
, PATH_MAX
);
1648 spin_unlock_irq(&css_set_lock
);
1650 if (len
>= PATH_MAX
)
1653 seq_escape(sf
, buf
, " \t\n\\");
1660 static int cgroup_show_options(struct seq_file
*seq
,
1661 struct kernfs_root
*kf_root
)
1663 struct cgroup_root
*root
= cgroup_root_from_kf(kf_root
);
1664 struct cgroup_subsys
*ss
;
1667 if (root
!= &cgrp_dfl_root
)
1668 for_each_subsys(ss
, ssid
)
1669 if (root
->subsys_mask
& (1 << ssid
))
1670 seq_show_option(seq
, ss
->legacy_name
, NULL
);
1671 if (root
->flags
& CGRP_ROOT_NOPREFIX
)
1672 seq_puts(seq
, ",noprefix");
1673 if (root
->flags
& CGRP_ROOT_XATTR
)
1674 seq_puts(seq
, ",xattr");
1676 spin_lock(&release_agent_path_lock
);
1677 if (strlen(root
->release_agent_path
))
1678 seq_show_option(seq
, "release_agent",
1679 root
->release_agent_path
);
1680 spin_unlock(&release_agent_path_lock
);
1682 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->cgrp
.flags
))
1683 seq_puts(seq
, ",clone_children");
1684 if (strlen(root
->name
))
1685 seq_show_option(seq
, "name", root
->name
);
1689 struct cgroup_sb_opts
{
1692 char *release_agent
;
1693 bool cpuset_clone_children
;
1695 /* User explicitly requested empty subsystem */
1699 static int parse_cgroupfs_options(char *data
, struct cgroup_sb_opts
*opts
)
1701 char *token
, *o
= data
;
1702 bool all_ss
= false, one_ss
= false;
1704 struct cgroup_subsys
*ss
;
1708 #ifdef CONFIG_CPUSETS
1709 mask
= ~((u16
)1 << cpuset_cgrp_id
);
1712 memset(opts
, 0, sizeof(*opts
));
1714 while ((token
= strsep(&o
, ",")) != NULL
) {
1719 if (!strcmp(token
, "none")) {
1720 /* Explicitly have no subsystems */
1724 if (!strcmp(token
, "all")) {
1725 /* Mutually exclusive option 'all' + subsystem name */
1731 if (!strcmp(token
, "noprefix")) {
1732 opts
->flags
|= CGRP_ROOT_NOPREFIX
;
1735 if (!strcmp(token
, "clone_children")) {
1736 opts
->cpuset_clone_children
= true;
1739 if (!strcmp(token
, "xattr")) {
1740 opts
->flags
|= CGRP_ROOT_XATTR
;
1743 if (!strncmp(token
, "release_agent=", 14)) {
1744 /* Specifying two release agents is forbidden */
1745 if (opts
->release_agent
)
1747 opts
->release_agent
=
1748 kstrndup(token
+ 14, PATH_MAX
- 1, GFP_KERNEL
);
1749 if (!opts
->release_agent
)
1753 if (!strncmp(token
, "name=", 5)) {
1754 const char *name
= token
+ 5;
1755 /* Can't specify an empty name */
1758 /* Must match [\w.-]+ */
1759 for (i
= 0; i
< strlen(name
); i
++) {
1763 if ((c
== '.') || (c
== '-') || (c
== '_'))
1767 /* Specifying two names is forbidden */
1770 opts
->name
= kstrndup(name
,
1771 MAX_CGROUP_ROOT_NAMELEN
- 1,
1779 for_each_subsys(ss
, i
) {
1780 if (strcmp(token
, ss
->legacy_name
))
1782 if (!cgroup_ssid_enabled(i
))
1784 if (cgroup_ssid_no_v1(i
))
1787 /* Mutually exclusive option 'all' + subsystem name */
1790 opts
->subsys_mask
|= (1 << i
);
1795 if (i
== CGROUP_SUBSYS_COUNT
)
1800 * If the 'all' option was specified select all the subsystems,
1801 * otherwise if 'none', 'name=' and a subsystem name options were
1802 * not specified, let's default to 'all'
1804 if (all_ss
|| (!one_ss
&& !opts
->none
&& !opts
->name
))
1805 for_each_subsys(ss
, i
)
1806 if (cgroup_ssid_enabled(i
) && !cgroup_ssid_no_v1(i
))
1807 opts
->subsys_mask
|= (1 << i
);
1810 * We either have to specify by name or by subsystems. (So all
1811 * empty hierarchies must have a name).
1813 if (!opts
->subsys_mask
&& !opts
->name
)
1817 * Option noprefix was introduced just for backward compatibility
1818 * with the old cpuset, so we allow noprefix only if mounting just
1819 * the cpuset subsystem.
1821 if ((opts
->flags
& CGRP_ROOT_NOPREFIX
) && (opts
->subsys_mask
& mask
))
1824 /* Can't specify "none" and some subsystems */
1825 if (opts
->subsys_mask
&& opts
->none
)
1831 static int cgroup_remount(struct kernfs_root
*kf_root
, int *flags
, char *data
)
1834 struct cgroup_root
*root
= cgroup_root_from_kf(kf_root
);
1835 struct cgroup_sb_opts opts
;
1836 u16 added_mask
, removed_mask
;
1838 if (root
== &cgrp_dfl_root
) {
1839 pr_err("remount is not allowed\n");
1843 cgroup_lock_and_drain_offline(&cgrp_dfl_root
.cgrp
);
1845 /* See what subsystems are wanted */
1846 ret
= parse_cgroupfs_options(data
, &opts
);
1850 if (opts
.subsys_mask
!= root
->subsys_mask
|| opts
.release_agent
)
1851 pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
1852 task_tgid_nr(current
), current
->comm
);
1854 added_mask
= opts
.subsys_mask
& ~root
->subsys_mask
;
1855 removed_mask
= root
->subsys_mask
& ~opts
.subsys_mask
;
1857 /* Don't allow flags or name to change at remount */
1858 if ((opts
.flags
^ root
->flags
) ||
1859 (opts
.name
&& strcmp(opts
.name
, root
->name
))) {
1860 pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
1861 opts
.flags
, opts
.name
?: "", root
->flags
, root
->name
);
1866 /* remounting is not allowed for populated hierarchies */
1867 if (!list_empty(&root
->cgrp
.self
.children
)) {
1872 ret
= rebind_subsystems(root
, added_mask
);
1876 WARN_ON(rebind_subsystems(&cgrp_dfl_root
, removed_mask
));
1878 if (opts
.release_agent
) {
1879 spin_lock(&release_agent_path_lock
);
1880 strcpy(root
->release_agent_path
, opts
.release_agent
);
1881 spin_unlock(&release_agent_path_lock
);
1884 kfree(opts
.release_agent
);
1886 mutex_unlock(&cgroup_mutex
);
1891 * To reduce the fork() overhead for systems that are not actually using
1892 * their cgroups capability, we don't maintain the lists running through
1893 * each css_set to its tasks until we see the list actually used - in other
1894 * words after the first mount.
1896 static bool use_task_css_set_links __read_mostly
;
1898 static void cgroup_enable_task_cg_lists(void)
1900 struct task_struct
*p
, *g
;
1902 spin_lock_irq(&css_set_lock
);
1904 if (use_task_css_set_links
)
1907 use_task_css_set_links
= true;
1910 * We need tasklist_lock because RCU is not safe against
1911 * while_each_thread(). Besides, a forking task that has passed
1912 * cgroup_post_fork() without seeing use_task_css_set_links = 1
1913 * is not guaranteed to have its child immediately visible in the
1914 * tasklist if we walk through it with RCU.
1916 read_lock(&tasklist_lock
);
1917 do_each_thread(g
, p
) {
1918 WARN_ON_ONCE(!list_empty(&p
->cg_list
) ||
1919 task_css_set(p
) != &init_css_set
);
1922 * We should check if the process is exiting, otherwise
1923 * it will race with cgroup_exit() in that the list
1924 * entry won't be deleted though the process has exited.
1925 * Do it while holding siglock so that we don't end up
1926 * racing against cgroup_exit().
1928 * Interrupts were already disabled while acquiring
1929 * the css_set_lock, so we do not need to disable it
1930 * again when acquiring the sighand->siglock here.
1932 spin_lock(&p
->sighand
->siglock
);
1933 if (!(p
->flags
& PF_EXITING
)) {
1934 struct css_set
*cset
= task_css_set(p
);
1936 if (!css_set_populated(cset
))
1937 css_set_update_populated(cset
, true);
1938 list_add_tail(&p
->cg_list
, &cset
->tasks
);
1941 spin_unlock(&p
->sighand
->siglock
);
1942 } while_each_thread(g
, p
);
1943 read_unlock(&tasklist_lock
);
1945 spin_unlock_irq(&css_set_lock
);
1948 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1950 struct cgroup_subsys
*ss
;
1953 INIT_LIST_HEAD(&cgrp
->self
.sibling
);
1954 INIT_LIST_HEAD(&cgrp
->self
.children
);
1955 INIT_LIST_HEAD(&cgrp
->cset_links
);
1956 INIT_LIST_HEAD(&cgrp
->pidlists
);
1957 mutex_init(&cgrp
->pidlist_mutex
);
1958 cgrp
->self
.cgroup
= cgrp
;
1959 cgrp
->self
.flags
|= CSS_ONLINE
;
1961 for_each_subsys(ss
, ssid
)
1962 INIT_LIST_HEAD(&cgrp
->e_csets
[ssid
]);
1964 init_waitqueue_head(&cgrp
->offline_waitq
);
1965 INIT_WORK(&cgrp
->release_agent_work
, cgroup_release_agent
);
1968 static void init_cgroup_root(struct cgroup_root
*root
,
1969 struct cgroup_sb_opts
*opts
)
1971 struct cgroup
*cgrp
= &root
->cgrp
;
1973 INIT_LIST_HEAD(&root
->root_list
);
1974 atomic_set(&root
->nr_cgrps
, 1);
1976 init_cgroup_housekeeping(cgrp
);
1977 idr_init(&root
->cgroup_idr
);
1979 root
->flags
= opts
->flags
;
1980 if (opts
->release_agent
)
1981 strcpy(root
->release_agent_path
, opts
->release_agent
);
1983 strcpy(root
->name
, opts
->name
);
1984 if (opts
->cpuset_clone_children
)
1985 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->cgrp
.flags
);
1988 static int cgroup_setup_root(struct cgroup_root
*root
, u16 ss_mask
)
1990 LIST_HEAD(tmp_links
);
1991 struct cgroup
*root_cgrp
= &root
->cgrp
;
1992 struct css_set
*cset
;
1995 lockdep_assert_held(&cgroup_mutex
);
1997 ret
= cgroup_idr_alloc(&root
->cgroup_idr
, root_cgrp
, 1, 2, GFP_KERNEL
);
2000 root_cgrp
->id
= ret
;
2001 root_cgrp
->ancestor_ids
[0] = ret
;
2003 ret
= percpu_ref_init(&root_cgrp
->self
.refcnt
, css_release
, 0,
2009 * We're accessing css_set_count without locking css_set_lock here,
2010 * but that's OK - it can only be increased by someone holding
2011 * cgroup_lock, and that's us. Later rebinding may disable
2012 * controllers on the default hierarchy and thus create new csets,
2013 * which can't be more than the existing ones. Allocate 2x.
2015 ret
= allocate_cgrp_cset_links(2 * css_set_count
, &tmp_links
);
2019 ret
= cgroup_init_root_id(root
);
2023 root
->kf_root
= kernfs_create_root(&cgroup_kf_syscall_ops
,
2024 KERNFS_ROOT_CREATE_DEACTIVATED
,
2026 if (IS_ERR(root
->kf_root
)) {
2027 ret
= PTR_ERR(root
->kf_root
);
2030 root_cgrp
->kn
= root
->kf_root
->kn
;
2032 ret
= css_populate_dir(&root_cgrp
->self
);
2036 ret
= rebind_subsystems(root
, ss_mask
);
2041 * There must be no failure case after here, since rebinding takes
2042 * care of subsystems' refcounts, which are explicitly dropped in
2043 * the failure exit path.
2045 list_add(&root
->root_list
, &cgroup_roots
);
2046 cgroup_root_count
++;
2049 * Link the root cgroup in this hierarchy into all the css_set
2052 spin_lock_irq(&css_set_lock
);
2053 hash_for_each(css_set_table
, i
, cset
, hlist
) {
2054 link_css_set(&tmp_links
, cset
, root_cgrp
);
2055 if (css_set_populated(cset
))
2056 cgroup_update_populated(root_cgrp
, true);
2058 spin_unlock_irq(&css_set_lock
);
2060 BUG_ON(!list_empty(&root_cgrp
->self
.children
));
2061 BUG_ON(atomic_read(&root
->nr_cgrps
) != 1);
2063 kernfs_activate(root_cgrp
->kn
);
2068 kernfs_destroy_root(root
->kf_root
);
2069 root
->kf_root
= NULL
;
2071 cgroup_exit_root_id(root
);
2073 percpu_ref_exit(&root_cgrp
->self
.refcnt
);
2075 free_cgrp_cset_links(&tmp_links
);
2079 static struct dentry
*cgroup_mount(struct file_system_type
*fs_type
,
2080 int flags
, const char *unused_dev_name
,
2083 bool is_v2
= fs_type
== &cgroup2_fs_type
;
2084 struct super_block
*pinned_sb
= NULL
;
2085 struct cgroup_namespace
*ns
= current
->nsproxy
->cgroup_ns
;
2086 struct cgroup_subsys
*ss
;
2087 struct cgroup_root
*root
;
2088 struct cgroup_sb_opts opts
;
2089 struct dentry
*dentry
;
2096 /* Check if the caller has permission to mount. */
2097 if (!ns_capable(ns
->user_ns
, CAP_SYS_ADMIN
)) {
2099 return ERR_PTR(-EPERM
);
2103 * The first time anyone tries to mount a cgroup, enable the list
2104 * linking each css_set to its tasks and fix up all existing tasks.
2106 if (!use_task_css_set_links
)
2107 cgroup_enable_task_cg_lists();
2111 pr_err("cgroup2: unknown option \"%s\"\n", (char *)data
);
2113 return ERR_PTR(-EINVAL
);
2115 cgrp_dfl_visible
= true;
2116 root
= &cgrp_dfl_root
;
2117 cgroup_get(&root
->cgrp
);
2121 cgroup_lock_and_drain_offline(&cgrp_dfl_root
.cgrp
);
2123 /* First find the desired set of subsystems */
2124 ret
= parse_cgroupfs_options(data
, &opts
);
2129 * Destruction of cgroup root is asynchronous, so subsystems may
2130 * still be dying after the previous unmount. Let's drain the
2131 * dying subsystems. We just need to ensure that the ones
2132 * unmounted previously finish dying and don't care about new ones
2133 * starting. Testing ref liveliness is good enough.
2135 for_each_subsys(ss
, i
) {
2136 if (!(opts
.subsys_mask
& (1 << i
)) ||
2137 ss
->root
== &cgrp_dfl_root
)
2140 if (!percpu_ref_tryget_live(&ss
->root
->cgrp
.self
.refcnt
)) {
2141 mutex_unlock(&cgroup_mutex
);
2143 ret
= restart_syscall();
2146 cgroup_put(&ss
->root
->cgrp
);
2149 for_each_root(root
) {
2150 bool name_match
= false;
2152 if (root
== &cgrp_dfl_root
)
2156 * If we asked for a name then it must match. Also, if
2157 * name matches but sybsys_mask doesn't, we should fail.
2158 * Remember whether name matched.
2161 if (strcmp(opts
.name
, root
->name
))
2167 * If we asked for subsystems (or explicitly for no
2168 * subsystems) then they must match.
2170 if ((opts
.subsys_mask
|| opts
.none
) &&
2171 (opts
.subsys_mask
!= root
->subsys_mask
)) {
2178 if (root
->flags
^ opts
.flags
)
2179 pr_warn("new mount options do not match the existing superblock, will be ignored\n");
2182 * We want to reuse @root whose lifetime is governed by its
2183 * ->cgrp. Let's check whether @root is alive and keep it
2184 * that way. As cgroup_kill_sb() can happen anytime, we
2185 * want to block it by pinning the sb so that @root doesn't
2186 * get killed before mount is complete.
2188 * With the sb pinned, tryget_live can reliably indicate
2189 * whether @root can be reused. If it's being killed,
2190 * drain it. We can use wait_queue for the wait but this
2191 * path is super cold. Let's just sleep a bit and retry.
2193 pinned_sb
= kernfs_pin_sb(root
->kf_root
, NULL
);
2194 if (IS_ERR(pinned_sb
) ||
2195 !percpu_ref_tryget_live(&root
->cgrp
.self
.refcnt
)) {
2196 mutex_unlock(&cgroup_mutex
);
2197 if (!IS_ERR_OR_NULL(pinned_sb
))
2198 deactivate_super(pinned_sb
);
2200 ret
= restart_syscall();
2209 * No such thing, create a new one. name= matching without subsys
2210 * specification is allowed for already existing hierarchies but we
2211 * can't create new one without subsys specification.
2213 if (!opts
.subsys_mask
&& !opts
.none
) {
2219 * We know this subsystem has not yet been bound. Users in a non-init
2220 * user namespace may only mount hierarchies with no bound subsystems,
2221 * i.e. 'none,name=user1'
2223 if (!opts
.none
&& !capable(CAP_SYS_ADMIN
)) {
2228 root
= kzalloc(sizeof(*root
), GFP_KERNEL
);
2234 init_cgroup_root(root
, &opts
);
2236 ret
= cgroup_setup_root(root
, opts
.subsys_mask
);
2238 cgroup_free_root(root
);
2241 mutex_unlock(&cgroup_mutex
);
2243 kfree(opts
.release_agent
);
2248 return ERR_PTR(ret
);
2251 dentry
= kernfs_mount(fs_type
, flags
, root
->kf_root
,
2252 is_v2
? CGROUP2_SUPER_MAGIC
: CGROUP_SUPER_MAGIC
,
2256 * In non-init cgroup namespace, instead of root cgroup's
2257 * dentry, we return the dentry corresponding to the
2258 * cgroupns->root_cgrp.
2260 if (!IS_ERR(dentry
) && ns
!= &init_cgroup_ns
) {
2261 struct dentry
*nsdentry
;
2262 struct cgroup
*cgrp
;
2264 mutex_lock(&cgroup_mutex
);
2265 spin_lock_irq(&css_set_lock
);
2267 cgrp
= cset_cgroup_from_root(ns
->root_cset
, root
);
2269 spin_unlock_irq(&css_set_lock
);
2270 mutex_unlock(&cgroup_mutex
);
2272 nsdentry
= kernfs_node_dentry(cgrp
->kn
, dentry
->d_sb
);
2277 if (IS_ERR(dentry
) || !new_sb
)
2278 cgroup_put(&root
->cgrp
);
2281 * If @pinned_sb, we're reusing an existing root and holding an
2282 * extra ref on its sb. Mount is complete. Put the extra ref.
2286 deactivate_super(pinned_sb
);
2293 static void cgroup_kill_sb(struct super_block
*sb
)
2295 struct kernfs_root
*kf_root
= kernfs_root_from_sb(sb
);
2296 struct cgroup_root
*root
= cgroup_root_from_kf(kf_root
);
2299 * If @root doesn't have any mounts or children, start killing it.
2300 * This prevents new mounts by disabling percpu_ref_tryget_live().
2301 * cgroup_mount() may wait for @root's release.
2303 * And don't kill the default root.
2305 if (!list_empty(&root
->cgrp
.self
.children
) ||
2306 root
== &cgrp_dfl_root
)
2307 cgroup_put(&root
->cgrp
);
2309 percpu_ref_kill(&root
->cgrp
.self
.refcnt
);
2314 static struct file_system_type cgroup_fs_type
= {
2316 .mount
= cgroup_mount
,
2317 .kill_sb
= cgroup_kill_sb
,
2318 .fs_flags
= FS_USERNS_MOUNT
,
2321 static struct file_system_type cgroup2_fs_type
= {
2323 .mount
= cgroup_mount
,
2324 .kill_sb
= cgroup_kill_sb
,
2325 .fs_flags
= FS_USERNS_MOUNT
,
2328 static char *cgroup_path_ns_locked(struct cgroup
*cgrp
, char *buf
, size_t buflen
,
2329 struct cgroup_namespace
*ns
)
2331 struct cgroup
*root
= cset_cgroup_from_root(ns
->root_cset
, cgrp
->root
);
2334 ret
= kernfs_path_from_node(cgrp
->kn
, root
->kn
, buf
, buflen
);
2335 if (ret
< 0 || ret
>= buflen
)
2340 char *cgroup_path_ns(struct cgroup
*cgrp
, char *buf
, size_t buflen
,
2341 struct cgroup_namespace
*ns
)
2345 mutex_lock(&cgroup_mutex
);
2346 spin_lock_irq(&css_set_lock
);
2348 ret
= cgroup_path_ns_locked(cgrp
, buf
, buflen
, ns
);
2350 spin_unlock_irq(&css_set_lock
);
2351 mutex_unlock(&cgroup_mutex
);
2355 EXPORT_SYMBOL_GPL(cgroup_path_ns
);
2358 * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
2359 * @task: target task
2360 * @buf: the buffer to write the path into
2361 * @buflen: the length of the buffer
2363 * Determine @task's cgroup on the first (the one with the lowest non-zero
2364 * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
2365 * function grabs cgroup_mutex and shouldn't be used inside locks used by
2366 * cgroup controller callbacks.
2368 * Return value is the same as kernfs_path().
2370 char *task_cgroup_path(struct task_struct
*task
, char *buf
, size_t buflen
)
2372 struct cgroup_root
*root
;
2373 struct cgroup
*cgrp
;
2374 int hierarchy_id
= 1;
2377 mutex_lock(&cgroup_mutex
);
2378 spin_lock_irq(&css_set_lock
);
2380 root
= idr_get_next(&cgroup_hierarchy_idr
, &hierarchy_id
);
2383 cgrp
= task_cgroup_from_root(task
, root
);
2384 path
= cgroup_path_ns_locked(cgrp
, buf
, buflen
, &init_cgroup_ns
);
2386 /* if no hierarchy exists, everyone is in "/" */
2387 if (strlcpy(buf
, "/", buflen
) < buflen
)
2391 spin_unlock_irq(&css_set_lock
);
2392 mutex_unlock(&cgroup_mutex
);
2395 EXPORT_SYMBOL_GPL(task_cgroup_path
);
2397 /* used to track tasks and other necessary states during migration */
2398 struct cgroup_taskset
{
2399 /* the src and dst cset list running through cset->mg_node */
2400 struct list_head src_csets
;
2401 struct list_head dst_csets
;
2403 /* the subsys currently being processed */
2407 * Fields for cgroup_taskset_*() iteration.
2409 * Before migration is committed, the target migration tasks are on
2410 * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
2411 * the csets on ->dst_csets. ->csets point to either ->src_csets
2412 * or ->dst_csets depending on whether migration is committed.
2414 * ->cur_csets and ->cur_task point to the current task position
2417 struct list_head
*csets
;
2418 struct css_set
*cur_cset
;
2419 struct task_struct
*cur_task
;
2422 #define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \
2423 .src_csets = LIST_HEAD_INIT(tset.src_csets), \
2424 .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
2425 .csets = &tset.src_csets, \
2429 * cgroup_taskset_add - try to add a migration target task to a taskset
2430 * @task: target task
2431 * @tset: target taskset
2433 * Add @task, which is a migration target, to @tset. This function becomes
2434 * noop if @task doesn't need to be migrated. @task's css_set should have
2435 * been added as a migration source and @task->cg_list will be moved from
2436 * the css_set's tasks list to mg_tasks one.
2438 static void cgroup_taskset_add(struct task_struct
*task
,
2439 struct cgroup_taskset
*tset
)
2441 struct css_set
*cset
;
2443 lockdep_assert_held(&css_set_lock
);
2445 /* @task either already exited or can't exit until the end */
2446 if (task
->flags
& PF_EXITING
)
2449 /* leave @task alone if post_fork() hasn't linked it yet */
2450 if (list_empty(&task
->cg_list
))
2453 cset
= task_css_set(task
);
2454 if (!cset
->mg_src_cgrp
)
2457 list_move_tail(&task
->cg_list
, &cset
->mg_tasks
);
2458 if (list_empty(&cset
->mg_node
))
2459 list_add_tail(&cset
->mg_node
, &tset
->src_csets
);
2460 if (list_empty(&cset
->mg_dst_cset
->mg_node
))
2461 list_move_tail(&cset
->mg_dst_cset
->mg_node
,
2466 * cgroup_taskset_first - reset taskset and return the first task
2467 * @tset: taskset of interest
2468 * @dst_cssp: output variable for the destination css
2470 * @tset iteration is initialized and the first task is returned.
2472 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
,
2473 struct cgroup_subsys_state
**dst_cssp
)
2475 tset
->cur_cset
= list_first_entry(tset
->csets
, struct css_set
, mg_node
);
2476 tset
->cur_task
= NULL
;
2478 return cgroup_taskset_next(tset
, dst_cssp
);
2482 * cgroup_taskset_next - iterate to the next task in taskset
2483 * @tset: taskset of interest
2484 * @dst_cssp: output variable for the destination css
2486 * Return the next task in @tset. Iteration must have been initialized
2487 * with cgroup_taskset_first().
2489 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
,
2490 struct cgroup_subsys_state
**dst_cssp
)
2492 struct css_set
*cset
= tset
->cur_cset
;
2493 struct task_struct
*task
= tset
->cur_task
;
2495 while (&cset
->mg_node
!= tset
->csets
) {
2497 task
= list_first_entry(&cset
->mg_tasks
,
2498 struct task_struct
, cg_list
);
2500 task
= list_next_entry(task
, cg_list
);
2502 if (&task
->cg_list
!= &cset
->mg_tasks
) {
2503 tset
->cur_cset
= cset
;
2504 tset
->cur_task
= task
;
2507 * This function may be called both before and
2508 * after cgroup_taskset_migrate(). The two cases
2509 * can be distinguished by looking at whether @cset
2510 * has its ->mg_dst_cset set.
2512 if (cset
->mg_dst_cset
)
2513 *dst_cssp
= cset
->mg_dst_cset
->subsys
[tset
->ssid
];
2515 *dst_cssp
= cset
->subsys
[tset
->ssid
];
2520 cset
= list_next_entry(cset
, mg_node
);
2528 * cgroup_taskset_migrate - migrate a taskset
2529 * @tset: taget taskset
2530 * @root: cgroup root the migration is taking place on
2532 * Migrate tasks in @tset as setup by migration preparation functions.
2533 * This function fails iff one of the ->can_attach callbacks fails and
2534 * guarantees that either all or none of the tasks in @tset are migrated.
2535 * @tset is consumed regardless of success.
2537 static int cgroup_taskset_migrate(struct cgroup_taskset
*tset
,
2538 struct cgroup_root
*root
)
2540 struct cgroup_subsys
*ss
;
2541 struct task_struct
*task
, *tmp_task
;
2542 struct css_set
*cset
, *tmp_cset
;
2543 int ssid
, failed_ssid
, ret
;
2545 /* methods shouldn't be called if no task is actually migrating */
2546 if (list_empty(&tset
->src_csets
))
2549 /* check that we can legitimately attach to the cgroup */
2550 do_each_subsys_mask(ss
, ssid
, root
->subsys_mask
) {
2551 if (ss
->can_attach
) {
2553 ret
= ss
->can_attach(tset
);
2556 goto out_cancel_attach
;
2559 } while_each_subsys_mask();
2562 * Now that we're guaranteed success, proceed to move all tasks to
2563 * the new cgroup. There are no failure cases after here, so this
2564 * is the commit point.
2566 spin_lock_irq(&css_set_lock
);
2567 list_for_each_entry(cset
, &tset
->src_csets
, mg_node
) {
2568 list_for_each_entry_safe(task
, tmp_task
, &cset
->mg_tasks
, cg_list
) {
2569 struct css_set
*from_cset
= task_css_set(task
);
2570 struct css_set
*to_cset
= cset
->mg_dst_cset
;
2572 get_css_set(to_cset
);
2573 css_set_move_task(task
, from_cset
, to_cset
, true);
2574 put_css_set_locked(from_cset
);
2577 spin_unlock_irq(&css_set_lock
);
2580 * Migration is committed, all target tasks are now on dst_csets.
2581 * Nothing is sensitive to fork() after this point. Notify
2582 * controllers that migration is complete.
2584 tset
->csets
= &tset
->dst_csets
;
2586 do_each_subsys_mask(ss
, ssid
, root
->subsys_mask
) {
2591 } while_each_subsys_mask();
2594 goto out_release_tset
;
2597 do_each_subsys_mask(ss
, ssid
, root
->subsys_mask
) {
2598 if (ssid
== failed_ssid
)
2600 if (ss
->cancel_attach
) {
2602 ss
->cancel_attach(tset
);
2604 } while_each_subsys_mask();
2606 spin_lock_irq(&css_set_lock
);
2607 list_splice_init(&tset
->dst_csets
, &tset
->src_csets
);
2608 list_for_each_entry_safe(cset
, tmp_cset
, &tset
->src_csets
, mg_node
) {
2609 list_splice_tail_init(&cset
->mg_tasks
, &cset
->tasks
);
2610 list_del_init(&cset
->mg_node
);
2612 spin_unlock_irq(&css_set_lock
);
2617 * cgroup_may_migrate_to - verify whether a cgroup can be migration destination
2618 * @dst_cgrp: destination cgroup to test
2620 * On the default hierarchy, except for the root, subtree_control must be
2621 * zero for migration destination cgroups with tasks so that child cgroups
2622 * don't compete against tasks.
2624 static bool cgroup_may_migrate_to(struct cgroup
*dst_cgrp
)
2626 return !cgroup_on_dfl(dst_cgrp
) || !cgroup_parent(dst_cgrp
) ||
2627 !dst_cgrp
->subtree_control
;
2631 * cgroup_migrate_finish - cleanup after attach
2632 * @preloaded_csets: list of preloaded css_sets
2634 * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
2635 * those functions for details.
2637 static void cgroup_migrate_finish(struct list_head
*preloaded_csets
)
2639 struct css_set
*cset
, *tmp_cset
;
2641 lockdep_assert_held(&cgroup_mutex
);
2643 spin_lock_irq(&css_set_lock
);
2644 list_for_each_entry_safe(cset
, tmp_cset
, preloaded_csets
, mg_preload_node
) {
2645 cset
->mg_src_cgrp
= NULL
;
2646 cset
->mg_dst_cgrp
= NULL
;
2647 cset
->mg_dst_cset
= NULL
;
2648 list_del_init(&cset
->mg_preload_node
);
2649 put_css_set_locked(cset
);
2651 spin_unlock_irq(&css_set_lock
);
2655 * cgroup_migrate_add_src - add a migration source css_set
2656 * @src_cset: the source css_set to add
2657 * @dst_cgrp: the destination cgroup
2658 * @preloaded_csets: list of preloaded css_sets
2660 * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
2661 * @src_cset and add it to @preloaded_csets, which should later be cleaned
2662 * up by cgroup_migrate_finish().
2664 * This function may be called without holding cgroup_threadgroup_rwsem
2665 * even if the target is a process. Threads may be created and destroyed
2666 * but as long as cgroup_mutex is not dropped, no new css_set can be put
2667 * into play and the preloaded css_sets are guaranteed to cover all
2670 static void cgroup_migrate_add_src(struct css_set
*src_cset
,
2671 struct cgroup
*dst_cgrp
,
2672 struct list_head
*preloaded_csets
)
2674 struct cgroup
*src_cgrp
;
2676 lockdep_assert_held(&cgroup_mutex
);
2677 lockdep_assert_held(&css_set_lock
);
2680 * If ->dead, @src_set is associated with one or more dead cgroups
2681 * and doesn't contain any migratable tasks. Ignore it early so
2682 * that the rest of migration path doesn't get confused by it.
2687 src_cgrp
= cset_cgroup_from_root(src_cset
, dst_cgrp
->root
);
2689 if (!list_empty(&src_cset
->mg_preload_node
))
2692 WARN_ON(src_cset
->mg_src_cgrp
);
2693 WARN_ON(src_cset
->mg_dst_cgrp
);
2694 WARN_ON(!list_empty(&src_cset
->mg_tasks
));
2695 WARN_ON(!list_empty(&src_cset
->mg_node
));
2697 src_cset
->mg_src_cgrp
= src_cgrp
;
2698 src_cset
->mg_dst_cgrp
= dst_cgrp
;
2699 get_css_set(src_cset
);
2700 list_add(&src_cset
->mg_preload_node
, preloaded_csets
);
2704 * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
2705 * @preloaded_csets: list of preloaded source css_sets
2707 * Tasks are about to be moved and all the source css_sets have been
2708 * preloaded to @preloaded_csets. This function looks up and pins all
2709 * destination css_sets, links each to its source, and append them to
2712 * This function must be called after cgroup_migrate_add_src() has been
2713 * called on each migration source css_set. After migration is performed
2714 * using cgroup_migrate(), cgroup_migrate_finish() must be called on
2717 static int cgroup_migrate_prepare_dst(struct list_head
*preloaded_csets
)
2720 struct css_set
*src_cset
, *tmp_cset
;
2722 lockdep_assert_held(&cgroup_mutex
);
2724 /* look up the dst cset for each src cset and link it to src */
2725 list_for_each_entry_safe(src_cset
, tmp_cset
, preloaded_csets
, mg_preload_node
) {
2726 struct css_set
*dst_cset
;
2728 dst_cset
= find_css_set(src_cset
, src_cset
->mg_dst_cgrp
);
2732 WARN_ON_ONCE(src_cset
->mg_dst_cset
|| dst_cset
->mg_dst_cset
);
2735 * If src cset equals dst, it's noop. Drop the src.
2736 * cgroup_migrate() will skip the cset too. Note that we
2737 * can't handle src == dst as some nodes are used by both.
2739 if (src_cset
== dst_cset
) {
2740 src_cset
->mg_src_cgrp
= NULL
;
2741 src_cset
->mg_dst_cgrp
= NULL
;
2742 list_del_init(&src_cset
->mg_preload_node
);
2743 put_css_set(src_cset
);
2744 put_css_set(dst_cset
);
2748 src_cset
->mg_dst_cset
= dst_cset
;
2750 if (list_empty(&dst_cset
->mg_preload_node
))
2751 list_add(&dst_cset
->mg_preload_node
, &csets
);
2753 put_css_set(dst_cset
);
2756 list_splice_tail(&csets
, preloaded_csets
);
2759 cgroup_migrate_finish(&csets
);
2764 * cgroup_migrate - migrate a process or task to a cgroup
2765 * @leader: the leader of the process or the task to migrate
2766 * @threadgroup: whether @leader points to the whole process or a single task
2767 * @root: cgroup root migration is taking place on
2769 * Migrate a process or task denoted by @leader. If migrating a process,
2770 * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
2771 * responsible for invoking cgroup_migrate_add_src() and
2772 * cgroup_migrate_prepare_dst() on the targets before invoking this
2773 * function and following up with cgroup_migrate_finish().
2775 * As long as a controller's ->can_attach() doesn't fail, this function is
2776 * guaranteed to succeed. This means that, excluding ->can_attach()
2777 * failure, when migrating multiple targets, the success or failure can be
2778 * decided for all targets by invoking group_migrate_prepare_dst() before
2779 * actually starting migrating.
2781 static int cgroup_migrate(struct task_struct
*leader
, bool threadgroup
,
2782 struct cgroup_root
*root
)
2784 struct cgroup_taskset tset
= CGROUP_TASKSET_INIT(tset
);
2785 struct task_struct
*task
;
2788 * Prevent freeing of tasks while we take a snapshot. Tasks that are
2789 * already PF_EXITING could be freed from underneath us unless we
2790 * take an rcu_read_lock.
2792 spin_lock_irq(&css_set_lock
);
2796 cgroup_taskset_add(task
, &tset
);
2799 } while_each_thread(leader
, task
);
2801 spin_unlock_irq(&css_set_lock
);
2803 return cgroup_taskset_migrate(&tset
, root
);
2807 * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
2808 * @dst_cgrp: the cgroup to attach to
2809 * @leader: the task or the leader of the threadgroup to be attached
2810 * @threadgroup: attach the whole threadgroup?
2812 * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
2814 static int cgroup_attach_task(struct cgroup
*dst_cgrp
,
2815 struct task_struct
*leader
, bool threadgroup
)
2817 LIST_HEAD(preloaded_csets
);
2818 struct task_struct
*task
;
2821 if (!cgroup_may_migrate_to(dst_cgrp
))
2824 /* look up all src csets */
2825 spin_lock_irq(&css_set_lock
);
2829 cgroup_migrate_add_src(task_css_set(task
), dst_cgrp
,
2833 } while_each_thread(leader
, task
);
2835 spin_unlock_irq(&css_set_lock
);
2837 /* prepare dst csets and commit */
2838 ret
= cgroup_migrate_prepare_dst(&preloaded_csets
);
2840 ret
= cgroup_migrate(leader
, threadgroup
, dst_cgrp
->root
);
2842 cgroup_migrate_finish(&preloaded_csets
);
2846 static int cgroup_procs_write_permission(struct task_struct
*task
,
2847 struct cgroup
*dst_cgrp
,
2848 struct kernfs_open_file
*of
)
2850 const struct cred
*cred
= current_cred();
2851 const struct cred
*tcred
= get_task_cred(task
);
2855 * even if we're attaching all tasks in the thread group, we only
2856 * need to check permissions on one of them.
2858 if (!uid_eq(cred
->euid
, GLOBAL_ROOT_UID
) &&
2859 !uid_eq(cred
->euid
, tcred
->uid
) &&
2860 !uid_eq(cred
->euid
, tcred
->suid
))
2863 if (!ret
&& cgroup_on_dfl(dst_cgrp
)) {
2864 struct super_block
*sb
= of
->file
->f_path
.dentry
->d_sb
;
2865 struct cgroup
*cgrp
;
2866 struct inode
*inode
;
2868 spin_lock_irq(&css_set_lock
);
2869 cgrp
= task_cgroup_from_root(task
, &cgrp_dfl_root
);
2870 spin_unlock_irq(&css_set_lock
);
2872 while (!cgroup_is_descendant(dst_cgrp
, cgrp
))
2873 cgrp
= cgroup_parent(cgrp
);
2876 inode
= kernfs_get_inode(sb
, cgrp
->procs_file
.kn
);
2878 ret
= inode_permission(inode
, MAY_WRITE
);
2888 * Find the task_struct of the task to attach by vpid and pass it along to the
2889 * function to attach either it or all tasks in its threadgroup. Will lock
2890 * cgroup_mutex and threadgroup.
2892 static ssize_t
__cgroup_procs_write(struct kernfs_open_file
*of
, char *buf
,
2893 size_t nbytes
, loff_t off
, bool threadgroup
)
2895 struct task_struct
*tsk
;
2896 struct cgroup_subsys
*ss
;
2897 struct cgroup
*cgrp
;
2901 if (kstrtoint(strstrip(buf
), 0, &pid
) || pid
< 0)
2904 cgrp
= cgroup_kn_lock_live(of
->kn
, false);
2908 percpu_down_write(&cgroup_threadgroup_rwsem
);
2911 tsk
= find_task_by_vpid(pid
);
2914 goto out_unlock_rcu
;
2921 tsk
= tsk
->group_leader
;
2924 * Workqueue threads may acquire PF_NO_SETAFFINITY and become
2925 * trapped in a cpuset, or RT worker may be born in a cgroup
2926 * with no rt_runtime allocated. Just say no.
2928 if (tsk
== kthreadd_task
|| (tsk
->flags
& PF_NO_SETAFFINITY
)) {
2930 goto out_unlock_rcu
;
2933 get_task_struct(tsk
);
2936 ret
= cgroup_procs_write_permission(tsk
, cgrp
, of
);
2938 ret
= cgroup_attach_task(cgrp
, tsk
, threadgroup
);
2940 put_task_struct(tsk
);
2941 goto out_unlock_threadgroup
;
2945 out_unlock_threadgroup
:
2946 percpu_up_write(&cgroup_threadgroup_rwsem
);
2947 for_each_subsys(ss
, ssid
)
2948 if (ss
->post_attach
)
2950 cgroup_kn_unlock(of
->kn
);
2951 return ret
?: nbytes
;
2955 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
2956 * @from: attach to all cgroups of a given task
2957 * @tsk: the task to be attached
2959 int cgroup_attach_task_all(struct task_struct
*from
, struct task_struct
*tsk
)
2961 struct cgroup_root
*root
;
2964 mutex_lock(&cgroup_mutex
);
2965 for_each_root(root
) {
2966 struct cgroup
*from_cgrp
;
2968 if (root
== &cgrp_dfl_root
)
2971 spin_lock_irq(&css_set_lock
);
2972 from_cgrp
= task_cgroup_from_root(from
, root
);
2973 spin_unlock_irq(&css_set_lock
);
2975 retval
= cgroup_attach_task(from_cgrp
, tsk
, false);
2979 mutex_unlock(&cgroup_mutex
);
2983 EXPORT_SYMBOL_GPL(cgroup_attach_task_all
);
2985 static ssize_t
cgroup_tasks_write(struct kernfs_open_file
*of
,
2986 char *buf
, size_t nbytes
, loff_t off
)
2988 return __cgroup_procs_write(of
, buf
, nbytes
, off
, false);
2991 static ssize_t
cgroup_procs_write(struct kernfs_open_file
*of
,
2992 char *buf
, size_t nbytes
, loff_t off
)
2994 return __cgroup_procs_write(of
, buf
, nbytes
, off
, true);
2997 static ssize_t
cgroup_release_agent_write(struct kernfs_open_file
*of
,
2998 char *buf
, size_t nbytes
, loff_t off
)
3000 struct cgroup
*cgrp
;
3002 BUILD_BUG_ON(sizeof(cgrp
->root
->release_agent_path
) < PATH_MAX
);
3004 cgrp
= cgroup_kn_lock_live(of
->kn
, false);
3007 spin_lock(&release_agent_path_lock
);
3008 strlcpy(cgrp
->root
->release_agent_path
, strstrip(buf
),
3009 sizeof(cgrp
->root
->release_agent_path
));
3010 spin_unlock(&release_agent_path_lock
);
3011 cgroup_kn_unlock(of
->kn
);
3015 static int cgroup_release_agent_show(struct seq_file
*seq
, void *v
)
3017 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
3019 spin_lock(&release_agent_path_lock
);
3020 seq_puts(seq
, cgrp
->root
->release_agent_path
);
3021 spin_unlock(&release_agent_path_lock
);
3022 seq_putc(seq
, '\n');
3026 static int cgroup_sane_behavior_show(struct seq_file
*seq
, void *v
)
3028 seq_puts(seq
, "0\n");
3032 static void cgroup_print_ss_mask(struct seq_file
*seq
, u16 ss_mask
)
3034 struct cgroup_subsys
*ss
;
3035 bool printed
= false;
3038 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
3041 seq_printf(seq
, "%s", ss
->name
);
3043 } while_each_subsys_mask();
3045 seq_putc(seq
, '\n');
3048 /* show controllers which are enabled from the parent */
3049 static int cgroup_controllers_show(struct seq_file
*seq
, void *v
)
3051 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
3053 cgroup_print_ss_mask(seq
, cgroup_control(cgrp
));
3057 /* show controllers which are enabled for a given cgroup's children */
3058 static int cgroup_subtree_control_show(struct seq_file
*seq
, void *v
)
3060 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
3062 cgroup_print_ss_mask(seq
, cgrp
->subtree_control
);
3067 * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
3068 * @cgrp: root of the subtree to update csses for
3070 * @cgrp's control masks have changed and its subtree's css associations
3071 * need to be updated accordingly. This function looks up all css_sets
3072 * which are attached to the subtree, creates the matching updated css_sets
3073 * and migrates the tasks to the new ones.
3075 static int cgroup_update_dfl_csses(struct cgroup
*cgrp
)
3077 LIST_HEAD(preloaded_csets
);
3078 struct cgroup_taskset tset
= CGROUP_TASKSET_INIT(tset
);
3079 struct cgroup_subsys_state
*d_css
;
3080 struct cgroup
*dsct
;
3081 struct css_set
*src_cset
;
3084 lockdep_assert_held(&cgroup_mutex
);
3086 percpu_down_write(&cgroup_threadgroup_rwsem
);
3088 /* look up all csses currently attached to @cgrp's subtree */
3089 spin_lock_irq(&css_set_lock
);
3090 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
3091 struct cgrp_cset_link
*link
;
3093 list_for_each_entry(link
, &dsct
->cset_links
, cset_link
)
3094 cgroup_migrate_add_src(link
->cset
, dsct
,
3097 spin_unlock_irq(&css_set_lock
);
3099 /* NULL dst indicates self on default hierarchy */
3100 ret
= cgroup_migrate_prepare_dst(&preloaded_csets
);
3104 spin_lock_irq(&css_set_lock
);
3105 list_for_each_entry(src_cset
, &preloaded_csets
, mg_preload_node
) {
3106 struct task_struct
*task
, *ntask
;
3108 /* src_csets precede dst_csets, break on the first dst_cset */
3109 if (!src_cset
->mg_src_cgrp
)
3112 /* all tasks in src_csets need to be migrated */
3113 list_for_each_entry_safe(task
, ntask
, &src_cset
->tasks
, cg_list
)
3114 cgroup_taskset_add(task
, &tset
);
3116 spin_unlock_irq(&css_set_lock
);
3118 ret
= cgroup_taskset_migrate(&tset
, cgrp
->root
);
3120 cgroup_migrate_finish(&preloaded_csets
);
3121 percpu_up_write(&cgroup_threadgroup_rwsem
);
3126 * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
3127 * @cgrp: root of the target subtree
3129 * Because css offlining is asynchronous, userland may try to re-enable a
3130 * controller while the previous css is still around. This function grabs
3131 * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
3133 static void cgroup_lock_and_drain_offline(struct cgroup
*cgrp
)
3134 __acquires(&cgroup_mutex
)
3136 struct cgroup
*dsct
;
3137 struct cgroup_subsys_state
*d_css
;
3138 struct cgroup_subsys
*ss
;
3142 mutex_lock(&cgroup_mutex
);
3144 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
3145 for_each_subsys(ss
, ssid
) {
3146 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
3149 if (!css
|| !percpu_ref_is_dying(&css
->refcnt
))
3153 prepare_to_wait(&dsct
->offline_waitq
, &wait
,
3154 TASK_UNINTERRUPTIBLE
);
3156 mutex_unlock(&cgroup_mutex
);
3158 finish_wait(&dsct
->offline_waitq
, &wait
);
3167 * cgroup_save_control - save control masks of a subtree
3168 * @cgrp: root of the target subtree
3170 * Save ->subtree_control and ->subtree_ss_mask to the respective old_
3171 * prefixed fields for @cgrp's subtree including @cgrp itself.
3173 static void cgroup_save_control(struct cgroup
*cgrp
)
3175 struct cgroup
*dsct
;
3176 struct cgroup_subsys_state
*d_css
;
3178 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
3179 dsct
->old_subtree_control
= dsct
->subtree_control
;
3180 dsct
->old_subtree_ss_mask
= dsct
->subtree_ss_mask
;
3185 * cgroup_propagate_control - refresh control masks of a subtree
3186 * @cgrp: root of the target subtree
3188 * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
3189 * ->subtree_control and propagate controller availability through the
3190 * subtree so that descendants don't have unavailable controllers enabled.
3192 static void cgroup_propagate_control(struct cgroup
*cgrp
)
3194 struct cgroup
*dsct
;
3195 struct cgroup_subsys_state
*d_css
;
3197 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
3198 dsct
->subtree_control
&= cgroup_control(dsct
);
3199 dsct
->subtree_ss_mask
=
3200 cgroup_calc_subtree_ss_mask(dsct
->subtree_control
,
3201 cgroup_ss_mask(dsct
));
3206 * cgroup_restore_control - restore control masks of a subtree
3207 * @cgrp: root of the target subtree
3209 * Restore ->subtree_control and ->subtree_ss_mask from the respective old_
3210 * prefixed fields for @cgrp's subtree including @cgrp itself.
3212 static void cgroup_restore_control(struct cgroup
*cgrp
)
3214 struct cgroup
*dsct
;
3215 struct cgroup_subsys_state
*d_css
;
3217 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
3218 dsct
->subtree_control
= dsct
->old_subtree_control
;
3219 dsct
->subtree_ss_mask
= dsct
->old_subtree_ss_mask
;
3223 static bool css_visible(struct cgroup_subsys_state
*css
)
3225 struct cgroup_subsys
*ss
= css
->ss
;
3226 struct cgroup
*cgrp
= css
->cgroup
;
3228 if (cgroup_control(cgrp
) & (1 << ss
->id
))
3230 if (!(cgroup_ss_mask(cgrp
) & (1 << ss
->id
)))
3232 return cgroup_on_dfl(cgrp
) && ss
->implicit_on_dfl
;
3236 * cgroup_apply_control_enable - enable or show csses according to control
3237 * @cgrp: root of the target subtree
3239 * Walk @cgrp's subtree and create new csses or make the existing ones
3240 * visible. A css is created invisible if it's being implicitly enabled
3241 * through dependency. An invisible css is made visible when the userland
3242 * explicitly enables it.
3244 * Returns 0 on success, -errno on failure. On failure, csses which have
3245 * been processed already aren't cleaned up. The caller is responsible for
3246 * cleaning up with cgroup_apply_control_disble().
3248 static int cgroup_apply_control_enable(struct cgroup
*cgrp
)
3250 struct cgroup
*dsct
;
3251 struct cgroup_subsys_state
*d_css
;
3252 struct cgroup_subsys
*ss
;
3255 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
3256 for_each_subsys(ss
, ssid
) {
3257 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
3259 WARN_ON_ONCE(css
&& percpu_ref_is_dying(&css
->refcnt
));
3261 if (!(cgroup_ss_mask(dsct
) & (1 << ss
->id
)))
3265 css
= css_create(dsct
, ss
);
3267 return PTR_ERR(css
);
3270 if (css_visible(css
)) {
3271 ret
= css_populate_dir(css
);
3282 * cgroup_apply_control_disable - kill or hide csses according to control
3283 * @cgrp: root of the target subtree
3285 * Walk @cgrp's subtree and kill and hide csses so that they match
3286 * cgroup_ss_mask() and cgroup_visible_mask().
3288 * A css is hidden when the userland requests it to be disabled while other
3289 * subsystems are still depending on it. The css must not actively control
3290 * resources and be in the vanilla state if it's made visible again later.
3291 * Controllers which may be depended upon should provide ->css_reset() for
3294 static void cgroup_apply_control_disable(struct cgroup
*cgrp
)
3296 struct cgroup
*dsct
;
3297 struct cgroup_subsys_state
*d_css
;
3298 struct cgroup_subsys
*ss
;
3301 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
3302 for_each_subsys(ss
, ssid
) {
3303 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
3305 WARN_ON_ONCE(css
&& percpu_ref_is_dying(&css
->refcnt
));
3311 !(cgroup_ss_mask(dsct
) & (1 << ss
->id
))) {
3313 } else if (!css_visible(css
)) {
3323 * cgroup_apply_control - apply control mask updates to the subtree
3324 * @cgrp: root of the target subtree
3326 * subsystems can be enabled and disabled in a subtree using the following
3329 * 1. Call cgroup_save_control() to stash the current state.
3330 * 2. Update ->subtree_control masks in the subtree as desired.
3331 * 3. Call cgroup_apply_control() to apply the changes.
3332 * 4. Optionally perform other related operations.
3333 * 5. Call cgroup_finalize_control() to finish up.
3335 * This function implements step 3 and propagates the mask changes
3336 * throughout @cgrp's subtree, updates csses accordingly and perform
3337 * process migrations.
3339 static int cgroup_apply_control(struct cgroup
*cgrp
)
3343 cgroup_propagate_control(cgrp
);
3345 ret
= cgroup_apply_control_enable(cgrp
);
3350 * At this point, cgroup_e_css() results reflect the new csses
3351 * making the following cgroup_update_dfl_csses() properly update
3352 * css associations of all tasks in the subtree.
3354 ret
= cgroup_update_dfl_csses(cgrp
);
3362 * cgroup_finalize_control - finalize control mask update
3363 * @cgrp: root of the target subtree
3364 * @ret: the result of the update
3366 * Finalize control mask update. See cgroup_apply_control() for more info.
3368 static void cgroup_finalize_control(struct cgroup
*cgrp
, int ret
)
3371 cgroup_restore_control(cgrp
);
3372 cgroup_propagate_control(cgrp
);
3375 cgroup_apply_control_disable(cgrp
);
3378 /* change the enabled child controllers for a cgroup in the default hierarchy */
3379 static ssize_t
cgroup_subtree_control_write(struct kernfs_open_file
*of
,
3380 char *buf
, size_t nbytes
,
3383 u16 enable
= 0, disable
= 0;
3384 struct cgroup
*cgrp
, *child
;
3385 struct cgroup_subsys
*ss
;
3390 * Parse input - space separated list of subsystem names prefixed
3391 * with either + or -.
3393 buf
= strstrip(buf
);
3394 while ((tok
= strsep(&buf
, " "))) {
3397 do_each_subsys_mask(ss
, ssid
, ~cgrp_dfl_inhibit_ss_mask
) {
3398 if (!cgroup_ssid_enabled(ssid
) ||
3399 strcmp(tok
+ 1, ss
->name
))
3403 enable
|= 1 << ssid
;
3404 disable
&= ~(1 << ssid
);
3405 } else if (*tok
== '-') {
3406 disable
|= 1 << ssid
;
3407 enable
&= ~(1 << ssid
);
3412 } while_each_subsys_mask();
3413 if (ssid
== CGROUP_SUBSYS_COUNT
)
3417 cgrp
= cgroup_kn_lock_live(of
->kn
, true);
3421 for_each_subsys(ss
, ssid
) {
3422 if (enable
& (1 << ssid
)) {
3423 if (cgrp
->subtree_control
& (1 << ssid
)) {
3424 enable
&= ~(1 << ssid
);
3428 if (!(cgroup_control(cgrp
) & (1 << ssid
))) {
3432 } else if (disable
& (1 << ssid
)) {
3433 if (!(cgrp
->subtree_control
& (1 << ssid
))) {
3434 disable
&= ~(1 << ssid
);
3438 /* a child has it enabled? */
3439 cgroup_for_each_live_child(child
, cgrp
) {
3440 if (child
->subtree_control
& (1 << ssid
)) {
3448 if (!enable
&& !disable
) {
3454 * Except for the root, subtree_control must be zero for a cgroup
3455 * with tasks so that child cgroups don't compete against tasks.
3457 if (enable
&& cgroup_parent(cgrp
) && !list_empty(&cgrp
->cset_links
)) {
3462 /* save and update control masks and prepare csses */
3463 cgroup_save_control(cgrp
);
3465 cgrp
->subtree_control
|= enable
;
3466 cgrp
->subtree_control
&= ~disable
;
3468 ret
= cgroup_apply_control(cgrp
);
3470 cgroup_finalize_control(cgrp
, ret
);
3472 kernfs_activate(cgrp
->kn
);
3475 cgroup_kn_unlock(of
->kn
);
3476 return ret
?: nbytes
;
3479 static int cgroup_events_show(struct seq_file
*seq
, void *v
)
3481 seq_printf(seq
, "populated %d\n",
3482 cgroup_is_populated(seq_css(seq
)->cgroup
));
3486 static ssize_t
cgroup_file_write(struct kernfs_open_file
*of
, char *buf
,
3487 size_t nbytes
, loff_t off
)
3489 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
3490 struct cftype
*cft
= of
->kn
->priv
;
3491 struct cgroup_subsys_state
*css
;
3495 return cft
->write(of
, buf
, nbytes
, off
);
3498 * kernfs guarantees that a file isn't deleted with operations in
3499 * flight, which means that the matching css is and stays alive and
3500 * doesn't need to be pinned. The RCU locking is not necessary
3501 * either. It's just for the convenience of using cgroup_css().
3504 css
= cgroup_css(cgrp
, cft
->ss
);
3507 if (cft
->write_u64
) {
3508 unsigned long long v
;
3509 ret
= kstrtoull(buf
, 0, &v
);
3511 ret
= cft
->write_u64(css
, cft
, v
);
3512 } else if (cft
->write_s64
) {
3514 ret
= kstrtoll(buf
, 0, &v
);
3516 ret
= cft
->write_s64(css
, cft
, v
);
3521 return ret
?: nbytes
;
3524 static void *cgroup_seqfile_start(struct seq_file
*seq
, loff_t
*ppos
)
3526 return seq_cft(seq
)->seq_start(seq
, ppos
);
3529 static void *cgroup_seqfile_next(struct seq_file
*seq
, void *v
, loff_t
*ppos
)
3531 return seq_cft(seq
)->seq_next(seq
, v
, ppos
);
3534 static void cgroup_seqfile_stop(struct seq_file
*seq
, void *v
)
3536 seq_cft(seq
)->seq_stop(seq
, v
);
3539 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
3541 struct cftype
*cft
= seq_cft(m
);
3542 struct cgroup_subsys_state
*css
= seq_css(m
);
3545 return cft
->seq_show(m
, arg
);
3548 seq_printf(m
, "%llu\n", cft
->read_u64(css
, cft
));
3549 else if (cft
->read_s64
)
3550 seq_printf(m
, "%lld\n", cft
->read_s64(css
, cft
));
3556 static struct kernfs_ops cgroup_kf_single_ops
= {
3557 .atomic_write_len
= PAGE_SIZE
,
3558 .write
= cgroup_file_write
,
3559 .seq_show
= cgroup_seqfile_show
,
3562 static struct kernfs_ops cgroup_kf_ops
= {
3563 .atomic_write_len
= PAGE_SIZE
,
3564 .write
= cgroup_file_write
,
3565 .seq_start
= cgroup_seqfile_start
,
3566 .seq_next
= cgroup_seqfile_next
,
3567 .seq_stop
= cgroup_seqfile_stop
,
3568 .seq_show
= cgroup_seqfile_show
,
3572 * cgroup_rename - Only allow simple rename of directories in place.
3574 static int cgroup_rename(struct kernfs_node
*kn
, struct kernfs_node
*new_parent
,
3575 const char *new_name_str
)
3577 struct cgroup
*cgrp
= kn
->priv
;
3580 if (kernfs_type(kn
) != KERNFS_DIR
)
3582 if (kn
->parent
!= new_parent
)
3586 * This isn't a proper migration and its usefulness is very
3587 * limited. Disallow on the default hierarchy.
3589 if (cgroup_on_dfl(cgrp
))
3593 * We're gonna grab cgroup_mutex which nests outside kernfs
3594 * active_ref. kernfs_rename() doesn't require active_ref
3595 * protection. Break them before grabbing cgroup_mutex.
3597 kernfs_break_active_protection(new_parent
);
3598 kernfs_break_active_protection(kn
);
3600 mutex_lock(&cgroup_mutex
);
3602 ret
= kernfs_rename(kn
, new_parent
, new_name_str
);
3604 mutex_unlock(&cgroup_mutex
);
3606 kernfs_unbreak_active_protection(kn
);
3607 kernfs_unbreak_active_protection(new_parent
);
3611 /* set uid and gid of cgroup dirs and files to that of the creator */
3612 static int cgroup_kn_set_ugid(struct kernfs_node
*kn
)
3614 struct iattr iattr
= { .ia_valid
= ATTR_UID
| ATTR_GID
,
3615 .ia_uid
= current_fsuid(),
3616 .ia_gid
= current_fsgid(), };
3618 if (uid_eq(iattr
.ia_uid
, GLOBAL_ROOT_UID
) &&
3619 gid_eq(iattr
.ia_gid
, GLOBAL_ROOT_GID
))
3622 return kernfs_setattr(kn
, &iattr
);
3625 static int cgroup_add_file(struct cgroup_subsys_state
*css
, struct cgroup
*cgrp
,
3628 char name
[CGROUP_FILE_NAME_MAX
];
3629 struct kernfs_node
*kn
;
3630 struct lock_class_key
*key
= NULL
;
3633 #ifdef CONFIG_DEBUG_LOCK_ALLOC
3634 key
= &cft
->lockdep_key
;
3636 kn
= __kernfs_create_file(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
),
3637 cgroup_file_mode(cft
), 0, cft
->kf_ops
, cft
,
3642 ret
= cgroup_kn_set_ugid(kn
);
3648 if (cft
->file_offset
) {
3649 struct cgroup_file
*cfile
= (void *)css
+ cft
->file_offset
;
3651 spin_lock_irq(&cgroup_file_kn_lock
);
3653 spin_unlock_irq(&cgroup_file_kn_lock
);
3660 * cgroup_addrm_files - add or remove files to a cgroup directory
3661 * @css: the target css
3662 * @cgrp: the target cgroup (usually css->cgroup)
3663 * @cfts: array of cftypes to be added
3664 * @is_add: whether to add or remove
3666 * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
3667 * For removals, this function never fails.
3669 static int cgroup_addrm_files(struct cgroup_subsys_state
*css
,
3670 struct cgroup
*cgrp
, struct cftype cfts
[],
3673 struct cftype
*cft
, *cft_end
= NULL
;
3676 lockdep_assert_held(&cgroup_mutex
);
3679 for (cft
= cfts
; cft
!= cft_end
&& cft
->name
[0] != '\0'; cft
++) {
3680 /* does cft->flags tell us to skip this file on @cgrp? */
3681 if ((cft
->flags
& __CFTYPE_ONLY_ON_DFL
) && !cgroup_on_dfl(cgrp
))
3683 if ((cft
->flags
& __CFTYPE_NOT_ON_DFL
) && cgroup_on_dfl(cgrp
))
3685 if ((cft
->flags
& CFTYPE_NOT_ON_ROOT
) && !cgroup_parent(cgrp
))
3687 if ((cft
->flags
& CFTYPE_ONLY_ON_ROOT
) && cgroup_parent(cgrp
))
3691 ret
= cgroup_add_file(css
, cgrp
, cft
);
3693 pr_warn("%s: failed to add %s, err=%d\n",
3694 __func__
, cft
->name
, ret
);
3700 cgroup_rm_file(cgrp
, cft
);
3706 static int cgroup_apply_cftypes(struct cftype
*cfts
, bool is_add
)
3709 struct cgroup_subsys
*ss
= cfts
[0].ss
;
3710 struct cgroup
*root
= &ss
->root
->cgrp
;
3711 struct cgroup_subsys_state
*css
;
3714 lockdep_assert_held(&cgroup_mutex
);
3716 /* add/rm files for all cgroups created before */
3717 css_for_each_descendant_pre(css
, cgroup_css(root
, ss
)) {
3718 struct cgroup
*cgrp
= css
->cgroup
;
3720 if (!(css
->flags
& CSS_VISIBLE
))
3723 ret
= cgroup_addrm_files(css
, cgrp
, cfts
, is_add
);
3729 kernfs_activate(root
->kn
);
3733 static void cgroup_exit_cftypes(struct cftype
*cfts
)
3737 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
3738 /* free copy for custom atomic_write_len, see init_cftypes() */
3739 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
)
3744 /* revert flags set by cgroup core while adding @cfts */
3745 cft
->flags
&= ~(__CFTYPE_ONLY_ON_DFL
| __CFTYPE_NOT_ON_DFL
);
3749 static int cgroup_init_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3753 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
3754 struct kernfs_ops
*kf_ops
;
3756 WARN_ON(cft
->ss
|| cft
->kf_ops
);
3759 kf_ops
= &cgroup_kf_ops
;
3761 kf_ops
= &cgroup_kf_single_ops
;
3764 * Ugh... if @cft wants a custom max_write_len, we need to
3765 * make a copy of kf_ops to set its atomic_write_len.
3767 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
) {
3768 kf_ops
= kmemdup(kf_ops
, sizeof(*kf_ops
), GFP_KERNEL
);
3770 cgroup_exit_cftypes(cfts
);
3773 kf_ops
->atomic_write_len
= cft
->max_write_len
;
3776 cft
->kf_ops
= kf_ops
;
3783 static int cgroup_rm_cftypes_locked(struct cftype
*cfts
)
3785 lockdep_assert_held(&cgroup_mutex
);
3787 if (!cfts
|| !cfts
[0].ss
)
3790 list_del(&cfts
->node
);
3791 cgroup_apply_cftypes(cfts
, false);
3792 cgroup_exit_cftypes(cfts
);
3797 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
3798 * @cfts: zero-length name terminated array of cftypes
3800 * Unregister @cfts. Files described by @cfts are removed from all
3801 * existing cgroups and all future cgroups won't have them either. This
3802 * function can be called anytime whether @cfts' subsys is attached or not.
3804 * Returns 0 on successful unregistration, -ENOENT if @cfts is not
3807 int cgroup_rm_cftypes(struct cftype
*cfts
)
3811 mutex_lock(&cgroup_mutex
);
3812 ret
= cgroup_rm_cftypes_locked(cfts
);
3813 mutex_unlock(&cgroup_mutex
);
3818 * cgroup_add_cftypes - add an array of cftypes to a subsystem
3819 * @ss: target cgroup subsystem
3820 * @cfts: zero-length name terminated array of cftypes
3822 * Register @cfts to @ss. Files described by @cfts are created for all
3823 * existing cgroups to which @ss is attached and all future cgroups will
3824 * have them too. This function can be called anytime whether @ss is
3827 * Returns 0 on successful registration, -errno on failure. Note that this
3828 * function currently returns 0 as long as @cfts registration is successful
3829 * even if some file creation attempts on existing cgroups fail.
3831 static int cgroup_add_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3835 if (!cgroup_ssid_enabled(ss
->id
))
3838 if (!cfts
|| cfts
[0].name
[0] == '\0')
3841 ret
= cgroup_init_cftypes(ss
, cfts
);
3845 mutex_lock(&cgroup_mutex
);
3847 list_add_tail(&cfts
->node
, &ss
->cfts
);
3848 ret
= cgroup_apply_cftypes(cfts
, true);
3850 cgroup_rm_cftypes_locked(cfts
);
3852 mutex_unlock(&cgroup_mutex
);
3857 * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
3858 * @ss: target cgroup subsystem
3859 * @cfts: zero-length name terminated array of cftypes
3861 * Similar to cgroup_add_cftypes() but the added files are only used for
3862 * the default hierarchy.
3864 int cgroup_add_dfl_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3868 for (cft
= cfts
; cft
&& cft
->name
[0] != '\0'; cft
++)
3869 cft
->flags
|= __CFTYPE_ONLY_ON_DFL
;
3870 return cgroup_add_cftypes(ss
, cfts
);
3874 * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
3875 * @ss: target cgroup subsystem
3876 * @cfts: zero-length name terminated array of cftypes
3878 * Similar to cgroup_add_cftypes() but the added files are only used for
3879 * the legacy hierarchies.
3881 int cgroup_add_legacy_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3885 for (cft
= cfts
; cft
&& cft
->name
[0] != '\0'; cft
++)
3886 cft
->flags
|= __CFTYPE_NOT_ON_DFL
;
3887 return cgroup_add_cftypes(ss
, cfts
);
3891 * cgroup_file_notify - generate a file modified event for a cgroup_file
3892 * @cfile: target cgroup_file
3894 * @cfile must have been obtained by setting cftype->file_offset.
3896 void cgroup_file_notify(struct cgroup_file
*cfile
)
3898 unsigned long flags
;
3900 spin_lock_irqsave(&cgroup_file_kn_lock
, flags
);
3902 kernfs_notify(cfile
->kn
);
3903 spin_unlock_irqrestore(&cgroup_file_kn_lock
, flags
);
3907 * cgroup_task_count - count the number of tasks in a cgroup.
3908 * @cgrp: the cgroup in question
3910 * Return the number of tasks in the cgroup.
3912 static int cgroup_task_count(const struct cgroup
*cgrp
)
3915 struct cgrp_cset_link
*link
;
3917 spin_lock_irq(&css_set_lock
);
3918 list_for_each_entry(link
, &cgrp
->cset_links
, cset_link
)
3919 count
+= atomic_read(&link
->cset
->refcount
);
3920 spin_unlock_irq(&css_set_lock
);
3925 * css_next_child - find the next child of a given css
3926 * @pos: the current position (%NULL to initiate traversal)
3927 * @parent: css whose children to walk
3929 * This function returns the next child of @parent and should be called
3930 * under either cgroup_mutex or RCU read lock. The only requirement is
3931 * that @parent and @pos are accessible. The next sibling is guaranteed to
3932 * be returned regardless of their states.
3934 * If a subsystem synchronizes ->css_online() and the start of iteration, a
3935 * css which finished ->css_online() is guaranteed to be visible in the
3936 * future iterations and will stay visible until the last reference is put.
3937 * A css which hasn't finished ->css_online() or already finished
3938 * ->css_offline() may show up during traversal. It's each subsystem's
3939 * responsibility to synchronize against on/offlining.
3941 struct cgroup_subsys_state
*css_next_child(struct cgroup_subsys_state
*pos
,
3942 struct cgroup_subsys_state
*parent
)
3944 struct cgroup_subsys_state
*next
;
3946 cgroup_assert_mutex_or_rcu_locked();
3949 * @pos could already have been unlinked from the sibling list.
3950 * Once a cgroup is removed, its ->sibling.next is no longer
3951 * updated when its next sibling changes. CSS_RELEASED is set when
3952 * @pos is taken off list, at which time its next pointer is valid,
3953 * and, as releases are serialized, the one pointed to by the next
3954 * pointer is guaranteed to not have started release yet. This
3955 * implies that if we observe !CSS_RELEASED on @pos in this RCU
3956 * critical section, the one pointed to by its next pointer is
3957 * guaranteed to not have finished its RCU grace period even if we
3958 * have dropped rcu_read_lock() inbetween iterations.
3960 * If @pos has CSS_RELEASED set, its next pointer can't be
3961 * dereferenced; however, as each css is given a monotonically
3962 * increasing unique serial number and always appended to the
3963 * sibling list, the next one can be found by walking the parent's
3964 * children until the first css with higher serial number than
3965 * @pos's. While this path can be slower, it happens iff iteration
3966 * races against release and the race window is very small.
3969 next
= list_entry_rcu(parent
->children
.next
, struct cgroup_subsys_state
, sibling
);
3970 } else if (likely(!(pos
->flags
& CSS_RELEASED
))) {
3971 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup_subsys_state
, sibling
);
3973 list_for_each_entry_rcu(next
, &parent
->children
, sibling
)
3974 if (next
->serial_nr
> pos
->serial_nr
)
3979 * @next, if not pointing to the head, can be dereferenced and is
3982 if (&next
->sibling
!= &parent
->children
)
3988 * css_next_descendant_pre - find the next descendant for pre-order walk
3989 * @pos: the current position (%NULL to initiate traversal)
3990 * @root: css whose descendants to walk
3992 * To be used by css_for_each_descendant_pre(). Find the next descendant
3993 * to visit for pre-order traversal of @root's descendants. @root is
3994 * included in the iteration and the first node to be visited.
3996 * While this function requires cgroup_mutex or RCU read locking, it
3997 * doesn't require the whole traversal to be contained in a single critical
3998 * section. This function will return the correct next descendant as long
3999 * as both @pos and @root are accessible and @pos is a descendant of @root.
4001 * If a subsystem synchronizes ->css_online() and the start of iteration, a
4002 * css which finished ->css_online() is guaranteed to be visible in the
4003 * future iterations and will stay visible until the last reference is put.
4004 * A css which hasn't finished ->css_online() or already finished
4005 * ->css_offline() may show up during traversal. It's each subsystem's
4006 * responsibility to synchronize against on/offlining.
4008 struct cgroup_subsys_state
*
4009 css_next_descendant_pre(struct cgroup_subsys_state
*pos
,
4010 struct cgroup_subsys_state
*root
)
4012 struct cgroup_subsys_state
*next
;
4014 cgroup_assert_mutex_or_rcu_locked();
4016 /* if first iteration, visit @root */
4020 /* visit the first child if exists */
4021 next
= css_next_child(NULL
, pos
);
4025 /* no child, visit my or the closest ancestor's next sibling */
4026 while (pos
!= root
) {
4027 next
= css_next_child(pos
, pos
->parent
);
4037 * css_rightmost_descendant - return the rightmost descendant of a css
4038 * @pos: css of interest
4040 * Return the rightmost descendant of @pos. If there's no descendant, @pos
4041 * is returned. This can be used during pre-order traversal to skip
4044 * While this function requires cgroup_mutex or RCU read locking, it
4045 * doesn't require the whole traversal to be contained in a single critical
4046 * section. This function will return the correct rightmost descendant as
4047 * long as @pos is accessible.
4049 struct cgroup_subsys_state
*
4050 css_rightmost_descendant(struct cgroup_subsys_state
*pos
)
4052 struct cgroup_subsys_state
*last
, *tmp
;
4054 cgroup_assert_mutex_or_rcu_locked();
4058 /* ->prev isn't RCU safe, walk ->next till the end */
4060 css_for_each_child(tmp
, last
)
4067 static struct cgroup_subsys_state
*
4068 css_leftmost_descendant(struct cgroup_subsys_state
*pos
)
4070 struct cgroup_subsys_state
*last
;
4074 pos
= css_next_child(NULL
, pos
);
4081 * css_next_descendant_post - find the next descendant for post-order walk
4082 * @pos: the current position (%NULL to initiate traversal)
4083 * @root: css whose descendants to walk
4085 * To be used by css_for_each_descendant_post(). Find the next descendant
4086 * to visit for post-order traversal of @root's descendants. @root is
4087 * included in the iteration and the last node to be visited.
4089 * While this function requires cgroup_mutex or RCU read locking, it
4090 * doesn't require the whole traversal to be contained in a single critical
4091 * section. This function will return the correct next descendant as long
4092 * as both @pos and @cgroup are accessible and @pos is a descendant of
4095 * If a subsystem synchronizes ->css_online() and the start of iteration, a
4096 * css which finished ->css_online() is guaranteed to be visible in the
4097 * future iterations and will stay visible until the last reference is put.
4098 * A css which hasn't finished ->css_online() or already finished
4099 * ->css_offline() may show up during traversal. It's each subsystem's
4100 * responsibility to synchronize against on/offlining.
4102 struct cgroup_subsys_state
*
4103 css_next_descendant_post(struct cgroup_subsys_state
*pos
,
4104 struct cgroup_subsys_state
*root
)
4106 struct cgroup_subsys_state
*next
;
4108 cgroup_assert_mutex_or_rcu_locked();
4110 /* if first iteration, visit leftmost descendant which may be @root */
4112 return css_leftmost_descendant(root
);
4114 /* if we visited @root, we're done */
4118 /* if there's an unvisited sibling, visit its leftmost descendant */
4119 next
= css_next_child(pos
, pos
->parent
);
4121 return css_leftmost_descendant(next
);
4123 /* no sibling left, visit parent */
4128 * css_has_online_children - does a css have online children
4129 * @css: the target css
4131 * Returns %true if @css has any online children; otherwise, %false. This
4132 * function can be called from any context but the caller is responsible
4133 * for synchronizing against on/offlining as necessary.
4135 bool css_has_online_children(struct cgroup_subsys_state
*css
)
4137 struct cgroup_subsys_state
*child
;
4141 css_for_each_child(child
, css
) {
4142 if (child
->flags
& CSS_ONLINE
) {
4152 * css_task_iter_advance_css_set - advance a task itererator to the next css_set
4153 * @it: the iterator to advance
4155 * Advance @it to the next css_set to walk.
4157 static void css_task_iter_advance_css_set(struct css_task_iter
*it
)
4159 struct list_head
*l
= it
->cset_pos
;
4160 struct cgrp_cset_link
*link
;
4161 struct css_set
*cset
;
4163 lockdep_assert_held(&css_set_lock
);
4165 /* Advance to the next non-empty css_set */
4168 if (l
== it
->cset_head
) {
4169 it
->cset_pos
= NULL
;
4170 it
->task_pos
= NULL
;
4175 cset
= container_of(l
, struct css_set
,
4176 e_cset_node
[it
->ss
->id
]);
4178 link
= list_entry(l
, struct cgrp_cset_link
, cset_link
);
4181 } while (!css_set_populated(cset
));
4185 if (!list_empty(&cset
->tasks
))
4186 it
->task_pos
= cset
->tasks
.next
;
4188 it
->task_pos
= cset
->mg_tasks
.next
;
4190 it
->tasks_head
= &cset
->tasks
;
4191 it
->mg_tasks_head
= &cset
->mg_tasks
;
4194 * We don't keep css_sets locked across iteration steps and thus
4195 * need to take steps to ensure that iteration can be resumed after
4196 * the lock is re-acquired. Iteration is performed at two levels -
4197 * css_sets and tasks in them.
4199 * Once created, a css_set never leaves its cgroup lists, so a
4200 * pinned css_set is guaranteed to stay put and we can resume
4201 * iteration afterwards.
4203 * Tasks may leave @cset across iteration steps. This is resolved
4204 * by registering each iterator with the css_set currently being
4205 * walked and making css_set_move_task() advance iterators whose
4206 * next task is leaving.
4209 list_del(&it
->iters_node
);
4210 put_css_set_locked(it
->cur_cset
);
4213 it
->cur_cset
= cset
;
4214 list_add(&it
->iters_node
, &cset
->task_iters
);
4217 static void css_task_iter_advance(struct css_task_iter
*it
)
4219 struct list_head
*l
= it
->task_pos
;
4221 lockdep_assert_held(&css_set_lock
);
4225 * Advance iterator to find next entry. cset->tasks is consumed
4226 * first and then ->mg_tasks. After ->mg_tasks, we move onto the
4231 if (l
== it
->tasks_head
)
4232 l
= it
->mg_tasks_head
->next
;
4234 if (l
== it
->mg_tasks_head
)
4235 css_task_iter_advance_css_set(it
);
4241 * css_task_iter_start - initiate task iteration
4242 * @css: the css to walk tasks of
4243 * @it: the task iterator to use
4245 * Initiate iteration through the tasks of @css. The caller can call
4246 * css_task_iter_next() to walk through the tasks until the function
4247 * returns NULL. On completion of iteration, css_task_iter_end() must be
4250 void css_task_iter_start(struct cgroup_subsys_state
*css
,
4251 struct css_task_iter
*it
)
4253 /* no one should try to iterate before mounting cgroups */
4254 WARN_ON_ONCE(!use_task_css_set_links
);
4256 memset(it
, 0, sizeof(*it
));
4258 spin_lock_irq(&css_set_lock
);
4263 it
->cset_pos
= &css
->cgroup
->e_csets
[css
->ss
->id
];
4265 it
->cset_pos
= &css
->cgroup
->cset_links
;
4267 it
->cset_head
= it
->cset_pos
;
4269 css_task_iter_advance_css_set(it
);
4271 spin_unlock_irq(&css_set_lock
);
4275 * css_task_iter_next - return the next task for the iterator
4276 * @it: the task iterator being iterated
4278 * The "next" function for task iteration. @it should have been
4279 * initialized via css_task_iter_start(). Returns NULL when the iteration
4282 struct task_struct
*css_task_iter_next(struct css_task_iter
*it
)
4285 put_task_struct(it
->cur_task
);
4286 it
->cur_task
= NULL
;
4289 spin_lock_irq(&css_set_lock
);
4292 it
->cur_task
= list_entry(it
->task_pos
, struct task_struct
,
4294 get_task_struct(it
->cur_task
);
4295 css_task_iter_advance(it
);
4298 spin_unlock_irq(&css_set_lock
);
4300 return it
->cur_task
;
4304 * css_task_iter_end - finish task iteration
4305 * @it: the task iterator to finish
4307 * Finish task iteration started by css_task_iter_start().
4309 void css_task_iter_end(struct css_task_iter
*it
)
4312 spin_lock_irq(&css_set_lock
);
4313 list_del(&it
->iters_node
);
4314 put_css_set_locked(it
->cur_cset
);
4315 spin_unlock_irq(&css_set_lock
);
4319 put_task_struct(it
->cur_task
);
4323 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
4324 * @to: cgroup to which the tasks will be moved
4325 * @from: cgroup in which the tasks currently reside
4327 * Locking rules between cgroup_post_fork() and the migration path
4328 * guarantee that, if a task is forking while being migrated, the new child
4329 * is guaranteed to be either visible in the source cgroup after the
4330 * parent's migration is complete or put into the target cgroup. No task
4331 * can slip out of migration through forking.
4333 int cgroup_transfer_tasks(struct cgroup
*to
, struct cgroup
*from
)
4335 LIST_HEAD(preloaded_csets
);
4336 struct cgrp_cset_link
*link
;
4337 struct css_task_iter it
;
4338 struct task_struct
*task
;
4341 if (!cgroup_may_migrate_to(to
))
4344 mutex_lock(&cgroup_mutex
);
4346 /* all tasks in @from are being moved, all csets are source */
4347 spin_lock_irq(&css_set_lock
);
4348 list_for_each_entry(link
, &from
->cset_links
, cset_link
)
4349 cgroup_migrate_add_src(link
->cset
, to
, &preloaded_csets
);
4350 spin_unlock_irq(&css_set_lock
);
4352 ret
= cgroup_migrate_prepare_dst(&preloaded_csets
);
4357 * Migrate tasks one-by-one until @from is empty. This fails iff
4358 * ->can_attach() fails.
4361 css_task_iter_start(&from
->self
, &it
);
4362 task
= css_task_iter_next(&it
);
4364 get_task_struct(task
);
4365 css_task_iter_end(&it
);
4368 ret
= cgroup_migrate(task
, false, to
->root
);
4369 put_task_struct(task
);
4371 } while (task
&& !ret
);
4373 cgroup_migrate_finish(&preloaded_csets
);
4374 mutex_unlock(&cgroup_mutex
);
4379 * Stuff for reading the 'tasks'/'procs' files.
4381 * Reading this file can return large amounts of data if a cgroup has
4382 * *lots* of attached tasks. So it may need several calls to read(),
4383 * but we cannot guarantee that the information we produce is correct
4384 * unless we produce it entirely atomically.
4388 /* which pidlist file are we talking about? */
4389 enum cgroup_filetype
{
4395 * A pidlist is a list of pids that virtually represents the contents of one
4396 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
4397 * a pair (one each for procs, tasks) for each pid namespace that's relevant
4400 struct cgroup_pidlist
{
4402 * used to find which pidlist is wanted. doesn't change as long as
4403 * this particular list stays in the list.
4405 struct { enum cgroup_filetype type
; struct pid_namespace
*ns
; } key
;
4408 /* how many elements the above list has */
4410 /* each of these stored in a list by its cgroup */
4411 struct list_head links
;
4412 /* pointer to the cgroup we belong to, for list removal purposes */
4413 struct cgroup
*owner
;
4414 /* for delayed destruction */
4415 struct delayed_work destroy_dwork
;
4419 * The following two functions "fix" the issue where there are more pids
4420 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
4421 * TODO: replace with a kernel-wide solution to this problem
4423 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
4424 static void *pidlist_allocate(int count
)
4426 if (PIDLIST_TOO_LARGE(count
))
4427 return vmalloc(count
* sizeof(pid_t
));
4429 return kmalloc(count
* sizeof(pid_t
), GFP_KERNEL
);
4432 static void pidlist_free(void *p
)
4438 * Used to destroy all pidlists lingering waiting for destroy timer. None
4439 * should be left afterwards.
4441 static void cgroup_pidlist_destroy_all(struct cgroup
*cgrp
)
4443 struct cgroup_pidlist
*l
, *tmp_l
;
4445 mutex_lock(&cgrp
->pidlist_mutex
);
4446 list_for_each_entry_safe(l
, tmp_l
, &cgrp
->pidlists
, links
)
4447 mod_delayed_work(cgroup_pidlist_destroy_wq
, &l
->destroy_dwork
, 0);
4448 mutex_unlock(&cgrp
->pidlist_mutex
);
4450 flush_workqueue(cgroup_pidlist_destroy_wq
);
4451 BUG_ON(!list_empty(&cgrp
->pidlists
));
4454 static void cgroup_pidlist_destroy_work_fn(struct work_struct
*work
)
4456 struct delayed_work
*dwork
= to_delayed_work(work
);
4457 struct cgroup_pidlist
*l
= container_of(dwork
, struct cgroup_pidlist
,
4459 struct cgroup_pidlist
*tofree
= NULL
;
4461 mutex_lock(&l
->owner
->pidlist_mutex
);
4464 * Destroy iff we didn't get queued again. The state won't change
4465 * as destroy_dwork can only be queued while locked.
4467 if (!delayed_work_pending(dwork
)) {
4468 list_del(&l
->links
);
4469 pidlist_free(l
->list
);
4470 put_pid_ns(l
->key
.ns
);
4474 mutex_unlock(&l
->owner
->pidlist_mutex
);
4479 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
4480 * Returns the number of unique elements.
4482 static int pidlist_uniq(pid_t
*list
, int length
)
4487 * we presume the 0th element is unique, so i starts at 1. trivial
4488 * edge cases first; no work needs to be done for either
4490 if (length
== 0 || length
== 1)
4492 /* src and dest walk down the list; dest counts unique elements */
4493 for (src
= 1; src
< length
; src
++) {
4494 /* find next unique element */
4495 while (list
[src
] == list
[src
-1]) {
4500 /* dest always points to where the next unique element goes */
4501 list
[dest
] = list
[src
];
4509 * The two pid files - task and cgroup.procs - guaranteed that the result
4510 * is sorted, which forced this whole pidlist fiasco. As pid order is
4511 * different per namespace, each namespace needs differently sorted list,
4512 * making it impossible to use, for example, single rbtree of member tasks
4513 * sorted by task pointer. As pidlists can be fairly large, allocating one
4514 * per open file is dangerous, so cgroup had to implement shared pool of
4515 * pidlists keyed by cgroup and namespace.
4517 * All this extra complexity was caused by the original implementation
4518 * committing to an entirely unnecessary property. In the long term, we
4519 * want to do away with it. Explicitly scramble sort order if on the
4520 * default hierarchy so that no such expectation exists in the new
4523 * Scrambling is done by swapping every two consecutive bits, which is
4524 * non-identity one-to-one mapping which disturbs sort order sufficiently.
4526 static pid_t
pid_fry(pid_t pid
)
4528 unsigned a
= pid
& 0x55555555;
4529 unsigned b
= pid
& 0xAAAAAAAA;
4531 return (a
<< 1) | (b
>> 1);
4534 static pid_t
cgroup_pid_fry(struct cgroup
*cgrp
, pid_t pid
)
4536 if (cgroup_on_dfl(cgrp
))
4537 return pid_fry(pid
);
4542 static int cmppid(const void *a
, const void *b
)
4544 return *(pid_t
*)a
- *(pid_t
*)b
;
4547 static int fried_cmppid(const void *a
, const void *b
)
4549 return pid_fry(*(pid_t
*)a
) - pid_fry(*(pid_t
*)b
);
4552 static struct cgroup_pidlist
*cgroup_pidlist_find(struct cgroup
*cgrp
,
4553 enum cgroup_filetype type
)
4555 struct cgroup_pidlist
*l
;
4556 /* don't need task_nsproxy() if we're looking at ourself */
4557 struct pid_namespace
*ns
= task_active_pid_ns(current
);
4559 lockdep_assert_held(&cgrp
->pidlist_mutex
);
4561 list_for_each_entry(l
, &cgrp
->pidlists
, links
)
4562 if (l
->key
.type
== type
&& l
->key
.ns
== ns
)
4568 * find the appropriate pidlist for our purpose (given procs vs tasks)
4569 * returns with the lock on that pidlist already held, and takes care
4570 * of the use count, or returns NULL with no locks held if we're out of
4573 static struct cgroup_pidlist
*cgroup_pidlist_find_create(struct cgroup
*cgrp
,
4574 enum cgroup_filetype type
)
4576 struct cgroup_pidlist
*l
;
4578 lockdep_assert_held(&cgrp
->pidlist_mutex
);
4580 l
= cgroup_pidlist_find(cgrp
, type
);
4584 /* entry not found; create a new one */
4585 l
= kzalloc(sizeof(struct cgroup_pidlist
), GFP_KERNEL
);
4589 INIT_DELAYED_WORK(&l
->destroy_dwork
, cgroup_pidlist_destroy_work_fn
);
4591 /* don't need task_nsproxy() if we're looking at ourself */
4592 l
->key
.ns
= get_pid_ns(task_active_pid_ns(current
));
4594 list_add(&l
->links
, &cgrp
->pidlists
);
4599 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
4601 static int pidlist_array_load(struct cgroup
*cgrp
, enum cgroup_filetype type
,
4602 struct cgroup_pidlist
**lp
)
4606 int pid
, n
= 0; /* used for populating the array */
4607 struct css_task_iter it
;
4608 struct task_struct
*tsk
;
4609 struct cgroup_pidlist
*l
;
4611 lockdep_assert_held(&cgrp
->pidlist_mutex
);
4614 * If cgroup gets more users after we read count, we won't have
4615 * enough space - tough. This race is indistinguishable to the
4616 * caller from the case that the additional cgroup users didn't
4617 * show up until sometime later on.
4619 length
= cgroup_task_count(cgrp
);
4620 array
= pidlist_allocate(length
);
4623 /* now, populate the array */
4624 css_task_iter_start(&cgrp
->self
, &it
);
4625 while ((tsk
= css_task_iter_next(&it
))) {
4626 if (unlikely(n
== length
))
4628 /* get tgid or pid for procs or tasks file respectively */
4629 if (type
== CGROUP_FILE_PROCS
)
4630 pid
= task_tgid_vnr(tsk
);
4632 pid
= task_pid_vnr(tsk
);
4633 if (pid
> 0) /* make sure to only use valid results */
4636 css_task_iter_end(&it
);
4638 /* now sort & (if procs) strip out duplicates */
4639 if (cgroup_on_dfl(cgrp
))
4640 sort(array
, length
, sizeof(pid_t
), fried_cmppid
, NULL
);
4642 sort(array
, length
, sizeof(pid_t
), cmppid
, NULL
);
4643 if (type
== CGROUP_FILE_PROCS
)
4644 length
= pidlist_uniq(array
, length
);
4646 l
= cgroup_pidlist_find_create(cgrp
, type
);
4648 pidlist_free(array
);
4652 /* store array, freeing old if necessary */
4653 pidlist_free(l
->list
);
4661 * cgroupstats_build - build and fill cgroupstats
4662 * @stats: cgroupstats to fill information into
4663 * @dentry: A dentry entry belonging to the cgroup for which stats have
4666 * Build and fill cgroupstats so that taskstats can export it to user
4669 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
)
4671 struct kernfs_node
*kn
= kernfs_node_from_dentry(dentry
);
4672 struct cgroup
*cgrp
;
4673 struct css_task_iter it
;
4674 struct task_struct
*tsk
;
4676 /* it should be kernfs_node belonging to cgroupfs and is a directory */
4677 if (dentry
->d_sb
->s_type
!= &cgroup_fs_type
|| !kn
||
4678 kernfs_type(kn
) != KERNFS_DIR
)
4681 mutex_lock(&cgroup_mutex
);
4684 * We aren't being called from kernfs and there's no guarantee on
4685 * @kn->priv's validity. For this and css_tryget_online_from_dir(),
4686 * @kn->priv is RCU safe. Let's do the RCU dancing.
4689 cgrp
= rcu_dereference(kn
->priv
);
4690 if (!cgrp
|| cgroup_is_dead(cgrp
)) {
4692 mutex_unlock(&cgroup_mutex
);
4697 css_task_iter_start(&cgrp
->self
, &it
);
4698 while ((tsk
= css_task_iter_next(&it
))) {
4699 switch (tsk
->state
) {
4701 stats
->nr_running
++;
4703 case TASK_INTERRUPTIBLE
:
4704 stats
->nr_sleeping
++;
4706 case TASK_UNINTERRUPTIBLE
:
4707 stats
->nr_uninterruptible
++;
4710 stats
->nr_stopped
++;
4713 if (delayacct_is_task_waiting_on_io(tsk
))
4714 stats
->nr_io_wait
++;
4718 css_task_iter_end(&it
);
4720 mutex_unlock(&cgroup_mutex
);
4726 * seq_file methods for the tasks/procs files. The seq_file position is the
4727 * next pid to display; the seq_file iterator is a pointer to the pid
4728 * in the cgroup->l->list array.
4731 static void *cgroup_pidlist_start(struct seq_file
*s
, loff_t
*pos
)
4734 * Initially we receive a position value that corresponds to
4735 * one more than the last pid shown (or 0 on the first call or
4736 * after a seek to the start). Use a binary-search to find the
4737 * next pid to display, if any
4739 struct kernfs_open_file
*of
= s
->private;
4740 struct cgroup
*cgrp
= seq_css(s
)->cgroup
;
4741 struct cgroup_pidlist
*l
;
4742 enum cgroup_filetype type
= seq_cft(s
)->private;
4743 int index
= 0, pid
= *pos
;
4746 mutex_lock(&cgrp
->pidlist_mutex
);
4749 * !NULL @of->priv indicates that this isn't the first start()
4750 * after open. If the matching pidlist is around, we can use that.
4751 * Look for it. Note that @of->priv can't be used directly. It
4752 * could already have been destroyed.
4755 of
->priv
= cgroup_pidlist_find(cgrp
, type
);
4758 * Either this is the first start() after open or the matching
4759 * pidlist has been destroyed inbetween. Create a new one.
4762 ret
= pidlist_array_load(cgrp
, type
,
4763 (struct cgroup_pidlist
**)&of
->priv
);
4765 return ERR_PTR(ret
);
4770 int end
= l
->length
;
4772 while (index
< end
) {
4773 int mid
= (index
+ end
) / 2;
4774 if (cgroup_pid_fry(cgrp
, l
->list
[mid
]) == pid
) {
4777 } else if (cgroup_pid_fry(cgrp
, l
->list
[mid
]) <= pid
)
4783 /* If we're off the end of the array, we're done */
4784 if (index
>= l
->length
)
4786 /* Update the abstract position to be the actual pid that we found */
4787 iter
= l
->list
+ index
;
4788 *pos
= cgroup_pid_fry(cgrp
, *iter
);
4792 static void cgroup_pidlist_stop(struct seq_file
*s
, void *v
)
4794 struct kernfs_open_file
*of
= s
->private;
4795 struct cgroup_pidlist
*l
= of
->priv
;
4798 mod_delayed_work(cgroup_pidlist_destroy_wq
, &l
->destroy_dwork
,
4799 CGROUP_PIDLIST_DESTROY_DELAY
);
4800 mutex_unlock(&seq_css(s
)->cgroup
->pidlist_mutex
);
4803 static void *cgroup_pidlist_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
4805 struct kernfs_open_file
*of
= s
->private;
4806 struct cgroup_pidlist
*l
= of
->priv
;
4808 pid_t
*end
= l
->list
+ l
->length
;
4810 * Advance to the next pid in the array. If this goes off the
4817 *pos
= cgroup_pid_fry(seq_css(s
)->cgroup
, *p
);
4822 static int cgroup_pidlist_show(struct seq_file
*s
, void *v
)
4824 seq_printf(s
, "%d\n", *(int *)v
);
4829 static u64
cgroup_read_notify_on_release(struct cgroup_subsys_state
*css
,
4832 return notify_on_release(css
->cgroup
);
4835 static int cgroup_write_notify_on_release(struct cgroup_subsys_state
*css
,
4836 struct cftype
*cft
, u64 val
)
4839 set_bit(CGRP_NOTIFY_ON_RELEASE
, &css
->cgroup
->flags
);
4841 clear_bit(CGRP_NOTIFY_ON_RELEASE
, &css
->cgroup
->flags
);
4845 static u64
cgroup_clone_children_read(struct cgroup_subsys_state
*css
,
4848 return test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
4851 static int cgroup_clone_children_write(struct cgroup_subsys_state
*css
,
4852 struct cftype
*cft
, u64 val
)
4855 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
4857 clear_bit(CGRP_CPUSET_CLONE_CHILDREN
, &css
->cgroup
->flags
);
4861 /* cgroup core interface files for the default hierarchy */
4862 static struct cftype cgroup_dfl_base_files
[] = {
4864 .name
= "cgroup.procs",
4865 .file_offset
= offsetof(struct cgroup
, procs_file
),
4866 .seq_start
= cgroup_pidlist_start
,
4867 .seq_next
= cgroup_pidlist_next
,
4868 .seq_stop
= cgroup_pidlist_stop
,
4869 .seq_show
= cgroup_pidlist_show
,
4870 .private = CGROUP_FILE_PROCS
,
4871 .write
= cgroup_procs_write
,
4874 .name
= "cgroup.controllers",
4875 .seq_show
= cgroup_controllers_show
,
4878 .name
= "cgroup.subtree_control",
4879 .seq_show
= cgroup_subtree_control_show
,
4880 .write
= cgroup_subtree_control_write
,
4883 .name
= "cgroup.events",
4884 .flags
= CFTYPE_NOT_ON_ROOT
,
4885 .file_offset
= offsetof(struct cgroup
, events_file
),
4886 .seq_show
= cgroup_events_show
,
4891 /* cgroup core interface files for the legacy hierarchies */
4892 static struct cftype cgroup_legacy_base_files
[] = {
4894 .name
= "cgroup.procs",
4895 .seq_start
= cgroup_pidlist_start
,
4896 .seq_next
= cgroup_pidlist_next
,
4897 .seq_stop
= cgroup_pidlist_stop
,
4898 .seq_show
= cgroup_pidlist_show
,
4899 .private = CGROUP_FILE_PROCS
,
4900 .write
= cgroup_procs_write
,
4903 .name
= "cgroup.clone_children",
4904 .read_u64
= cgroup_clone_children_read
,
4905 .write_u64
= cgroup_clone_children_write
,
4908 .name
= "cgroup.sane_behavior",
4909 .flags
= CFTYPE_ONLY_ON_ROOT
,
4910 .seq_show
= cgroup_sane_behavior_show
,
4914 .seq_start
= cgroup_pidlist_start
,
4915 .seq_next
= cgroup_pidlist_next
,
4916 .seq_stop
= cgroup_pidlist_stop
,
4917 .seq_show
= cgroup_pidlist_show
,
4918 .private = CGROUP_FILE_TASKS
,
4919 .write
= cgroup_tasks_write
,
4922 .name
= "notify_on_release",
4923 .read_u64
= cgroup_read_notify_on_release
,
4924 .write_u64
= cgroup_write_notify_on_release
,
4927 .name
= "release_agent",
4928 .flags
= CFTYPE_ONLY_ON_ROOT
,
4929 .seq_show
= cgroup_release_agent_show
,
4930 .write
= cgroup_release_agent_write
,
4931 .max_write_len
= PATH_MAX
- 1,
4937 * css destruction is four-stage process.
4939 * 1. Destruction starts. Killing of the percpu_ref is initiated.
4940 * Implemented in kill_css().
4942 * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
4943 * and thus css_tryget_online() is guaranteed to fail, the css can be
4944 * offlined by invoking offline_css(). After offlining, the base ref is
4945 * put. Implemented in css_killed_work_fn().
4947 * 3. When the percpu_ref reaches zero, the only possible remaining
4948 * accessors are inside RCU read sections. css_release() schedules the
4951 * 4. After the grace period, the css can be freed. Implemented in
4952 * css_free_work_fn().
4954 * It is actually hairier because both step 2 and 4 require process context
4955 * and thus involve punting to css->destroy_work adding two additional
4956 * steps to the already complex sequence.
4958 static void css_free_work_fn(struct work_struct
*work
)
4960 struct cgroup_subsys_state
*css
=
4961 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
4962 struct cgroup_subsys
*ss
= css
->ss
;
4963 struct cgroup
*cgrp
= css
->cgroup
;
4965 percpu_ref_exit(&css
->refcnt
);
4969 struct cgroup_subsys_state
*parent
= css
->parent
;
4973 cgroup_idr_remove(&ss
->css_idr
, id
);
4979 /* cgroup free path */
4980 atomic_dec(&cgrp
->root
->nr_cgrps
);
4981 cgroup_pidlist_destroy_all(cgrp
);
4982 cancel_work_sync(&cgrp
->release_agent_work
);
4984 if (cgroup_parent(cgrp
)) {
4986 * We get a ref to the parent, and put the ref when
4987 * this cgroup is being freed, so it's guaranteed
4988 * that the parent won't be destroyed before its
4991 cgroup_put(cgroup_parent(cgrp
));
4992 kernfs_put(cgrp
->kn
);
4996 * This is root cgroup's refcnt reaching zero,
4997 * which indicates that the root should be
5000 cgroup_destroy_root(cgrp
->root
);
5005 static void css_free_rcu_fn(struct rcu_head
*rcu_head
)
5007 struct cgroup_subsys_state
*css
=
5008 container_of(rcu_head
, struct cgroup_subsys_state
, rcu_head
);
5010 INIT_WORK(&css
->destroy_work
, css_free_work_fn
);
5011 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
5014 static void css_release_work_fn(struct work_struct
*work
)
5016 struct cgroup_subsys_state
*css
=
5017 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
5018 struct cgroup_subsys
*ss
= css
->ss
;
5019 struct cgroup
*cgrp
= css
->cgroup
;
5021 mutex_lock(&cgroup_mutex
);
5023 css
->flags
|= CSS_RELEASED
;
5024 list_del_rcu(&css
->sibling
);
5027 /* css release path */
5028 cgroup_idr_replace(&ss
->css_idr
, NULL
, css
->id
);
5029 if (ss
->css_released
)
5030 ss
->css_released(css
);
5032 /* cgroup release path */
5033 cgroup_idr_remove(&cgrp
->root
->cgroup_idr
, cgrp
->id
);
5037 * There are two control paths which try to determine
5038 * cgroup from dentry without going through kernfs -
5039 * cgroupstats_build() and css_tryget_online_from_dir().
5040 * Those are supported by RCU protecting clearing of
5041 * cgrp->kn->priv backpointer.
5044 RCU_INIT_POINTER(*(void __rcu __force
**)&cgrp
->kn
->priv
,
5048 mutex_unlock(&cgroup_mutex
);
5050 call_rcu(&css
->rcu_head
, css_free_rcu_fn
);
5053 static void css_release(struct percpu_ref
*ref
)
5055 struct cgroup_subsys_state
*css
=
5056 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
5058 INIT_WORK(&css
->destroy_work
, css_release_work_fn
);
5059 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
5062 static void init_and_link_css(struct cgroup_subsys_state
*css
,
5063 struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
5065 lockdep_assert_held(&cgroup_mutex
);
5069 memset(css
, 0, sizeof(*css
));
5073 INIT_LIST_HEAD(&css
->sibling
);
5074 INIT_LIST_HEAD(&css
->children
);
5075 css
->serial_nr
= css_serial_nr_next
++;
5076 atomic_set(&css
->online_cnt
, 0);
5078 if (cgroup_parent(cgrp
)) {
5079 css
->parent
= cgroup_css(cgroup_parent(cgrp
), ss
);
5080 css_get(css
->parent
);
5083 BUG_ON(cgroup_css(cgrp
, ss
));
5086 /* invoke ->css_online() on a new CSS and mark it online if successful */
5087 static int online_css(struct cgroup_subsys_state
*css
)
5089 struct cgroup_subsys
*ss
= css
->ss
;
5092 lockdep_assert_held(&cgroup_mutex
);
5095 ret
= ss
->css_online(css
);
5097 css
->flags
|= CSS_ONLINE
;
5098 rcu_assign_pointer(css
->cgroup
->subsys
[ss
->id
], css
);
5100 atomic_inc(&css
->online_cnt
);
5102 atomic_inc(&css
->parent
->online_cnt
);
5107 /* if the CSS is online, invoke ->css_offline() on it and mark it offline */
5108 static void offline_css(struct cgroup_subsys_state
*css
)
5110 struct cgroup_subsys
*ss
= css
->ss
;
5112 lockdep_assert_held(&cgroup_mutex
);
5114 if (!(css
->flags
& CSS_ONLINE
))
5120 if (ss
->css_offline
)
5121 ss
->css_offline(css
);
5123 css
->flags
&= ~CSS_ONLINE
;
5124 RCU_INIT_POINTER(css
->cgroup
->subsys
[ss
->id
], NULL
);
5126 wake_up_all(&css
->cgroup
->offline_waitq
);
5130 * css_create - create a cgroup_subsys_state
5131 * @cgrp: the cgroup new css will be associated with
5132 * @ss: the subsys of new css
5134 * Create a new css associated with @cgrp - @ss pair. On success, the new
5135 * css is online and installed in @cgrp. This function doesn't create the
5136 * interface files. Returns 0 on success, -errno on failure.
5138 static struct cgroup_subsys_state
*css_create(struct cgroup
*cgrp
,
5139 struct cgroup_subsys
*ss
)
5141 struct cgroup
*parent
= cgroup_parent(cgrp
);
5142 struct cgroup_subsys_state
*parent_css
= cgroup_css(parent
, ss
);
5143 struct cgroup_subsys_state
*css
;
5146 lockdep_assert_held(&cgroup_mutex
);
5148 css
= ss
->css_alloc(parent_css
);
5152 init_and_link_css(css
, ss
, cgrp
);
5154 err
= percpu_ref_init(&css
->refcnt
, css_release
, 0, GFP_KERNEL
);
5158 err
= cgroup_idr_alloc(&ss
->css_idr
, NULL
, 2, 0, GFP_KERNEL
);
5163 /* @css is ready to be brought online now, make it visible */
5164 list_add_tail_rcu(&css
->sibling
, &parent_css
->children
);
5165 cgroup_idr_replace(&ss
->css_idr
, css
, css
->id
);
5167 err
= online_css(css
);
5171 if (ss
->broken_hierarchy
&& !ss
->warned_broken_hierarchy
&&
5172 cgroup_parent(parent
)) {
5173 pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
5174 current
->comm
, current
->pid
, ss
->name
);
5175 if (!strcmp(ss
->name
, "memory"))
5176 pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
5177 ss
->warned_broken_hierarchy
= true;
5183 list_del_rcu(&css
->sibling
);
5185 call_rcu(&css
->rcu_head
, css_free_rcu_fn
);
5186 return ERR_PTR(err
);
5189 static struct cgroup
*cgroup_create(struct cgroup
*parent
)
5191 struct cgroup_root
*root
= parent
->root
;
5192 struct cgroup
*cgrp
, *tcgrp
;
5193 int level
= parent
->level
+ 1;
5196 /* allocate the cgroup and its ID, 0 is reserved for the root */
5197 cgrp
= kzalloc(sizeof(*cgrp
) +
5198 sizeof(cgrp
->ancestor_ids
[0]) * (level
+ 1), GFP_KERNEL
);
5200 return ERR_PTR(-ENOMEM
);
5202 ret
= percpu_ref_init(&cgrp
->self
.refcnt
, css_release
, 0, GFP_KERNEL
);
5207 * Temporarily set the pointer to NULL, so idr_find() won't return
5208 * a half-baked cgroup.
5210 cgrp
->id
= cgroup_idr_alloc(&root
->cgroup_idr
, NULL
, 2, 0, GFP_KERNEL
);
5213 goto out_cancel_ref
;
5216 init_cgroup_housekeeping(cgrp
);
5218 cgrp
->self
.parent
= &parent
->self
;
5220 cgrp
->level
= level
;
5222 for (tcgrp
= cgrp
; tcgrp
; tcgrp
= cgroup_parent(tcgrp
))
5223 cgrp
->ancestor_ids
[tcgrp
->level
] = tcgrp
->id
;
5225 if (notify_on_release(parent
))
5226 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
5228 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
))
5229 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
5231 cgrp
->self
.serial_nr
= css_serial_nr_next
++;
5233 /* allocation complete, commit to creation */
5234 list_add_tail_rcu(&cgrp
->self
.sibling
, &cgroup_parent(cgrp
)->self
.children
);
5235 atomic_inc(&root
->nr_cgrps
);
5239 * @cgrp is now fully operational. If something fails after this
5240 * point, it'll be released via the normal destruction path.
5242 cgroup_idr_replace(&root
->cgroup_idr
, cgrp
, cgrp
->id
);
5245 * On the default hierarchy, a child doesn't automatically inherit
5246 * subtree_control from the parent. Each is configured manually.
5248 if (!cgroup_on_dfl(cgrp
))
5249 cgrp
->subtree_control
= cgroup_control(cgrp
);
5251 cgroup_propagate_control(cgrp
);
5253 /* @cgrp doesn't have dir yet so the following will only create csses */
5254 ret
= cgroup_apply_control_enable(cgrp
);
5261 percpu_ref_exit(&cgrp
->self
.refcnt
);
5264 return ERR_PTR(ret
);
5266 cgroup_destroy_locked(cgrp
);
5267 return ERR_PTR(ret
);
5270 static int cgroup_mkdir(struct kernfs_node
*parent_kn
, const char *name
,
5273 struct cgroup
*parent
, *cgrp
;
5274 struct kernfs_node
*kn
;
5277 /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
5278 if (strchr(name
, '\n'))
5281 parent
= cgroup_kn_lock_live(parent_kn
, false);
5285 cgrp
= cgroup_create(parent
);
5287 ret
= PTR_ERR(cgrp
);
5291 /* create the directory */
5292 kn
= kernfs_create_dir(parent
->kn
, name
, mode
, cgrp
);
5300 * This extra ref will be put in cgroup_free_fn() and guarantees
5301 * that @cgrp->kn is always accessible.
5305 ret
= cgroup_kn_set_ugid(kn
);
5309 ret
= css_populate_dir(&cgrp
->self
);
5313 ret
= cgroup_apply_control_enable(cgrp
);
5317 /* let's create and online css's */
5318 kernfs_activate(kn
);
5324 cgroup_destroy_locked(cgrp
);
5326 cgroup_kn_unlock(parent_kn
);
5331 * This is called when the refcnt of a css is confirmed to be killed.
5332 * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
5333 * initate destruction and put the css ref from kill_css().
5335 static void css_killed_work_fn(struct work_struct
*work
)
5337 struct cgroup_subsys_state
*css
=
5338 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
5340 mutex_lock(&cgroup_mutex
);
5345 /* @css can't go away while we're holding cgroup_mutex */
5347 } while (css
&& atomic_dec_and_test(&css
->online_cnt
));
5349 mutex_unlock(&cgroup_mutex
);
5352 /* css kill confirmation processing requires process context, bounce */
5353 static void css_killed_ref_fn(struct percpu_ref
*ref
)
5355 struct cgroup_subsys_state
*css
=
5356 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
5358 if (atomic_dec_and_test(&css
->online_cnt
)) {
5359 INIT_WORK(&css
->destroy_work
, css_killed_work_fn
);
5360 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
5365 * kill_css - destroy a css
5366 * @css: css to destroy
5368 * This function initiates destruction of @css by removing cgroup interface
5369 * files and putting its base reference. ->css_offline() will be invoked
5370 * asynchronously once css_tryget_online() is guaranteed to fail and when
5371 * the reference count reaches zero, @css will be released.
5373 static void kill_css(struct cgroup_subsys_state
*css
)
5375 lockdep_assert_held(&cgroup_mutex
);
5378 * This must happen before css is disassociated with its cgroup.
5379 * See seq_css() for details.
5384 * Killing would put the base ref, but we need to keep it alive
5385 * until after ->css_offline().
5390 * cgroup core guarantees that, by the time ->css_offline() is
5391 * invoked, no new css reference will be given out via
5392 * css_tryget_online(). We can't simply call percpu_ref_kill() and
5393 * proceed to offlining css's because percpu_ref_kill() doesn't
5394 * guarantee that the ref is seen as killed on all CPUs on return.
5396 * Use percpu_ref_kill_and_confirm() to get notifications as each
5397 * css is confirmed to be seen as killed on all CPUs.
5399 percpu_ref_kill_and_confirm(&css
->refcnt
, css_killed_ref_fn
);
5403 * cgroup_destroy_locked - the first stage of cgroup destruction
5404 * @cgrp: cgroup to be destroyed
5406 * css's make use of percpu refcnts whose killing latency shouldn't be
5407 * exposed to userland and are RCU protected. Also, cgroup core needs to
5408 * guarantee that css_tryget_online() won't succeed by the time
5409 * ->css_offline() is invoked. To satisfy all the requirements,
5410 * destruction is implemented in the following two steps.
5412 * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
5413 * userland visible parts and start killing the percpu refcnts of
5414 * css's. Set up so that the next stage will be kicked off once all
5415 * the percpu refcnts are confirmed to be killed.
5417 * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
5418 * rest of destruction. Once all cgroup references are gone, the
5419 * cgroup is RCU-freed.
5421 * This function implements s1. After this step, @cgrp is gone as far as
5422 * the userland is concerned and a new cgroup with the same name may be
5423 * created. As cgroup doesn't care about the names internally, this
5424 * doesn't cause any problem.
5426 static int cgroup_destroy_locked(struct cgroup
*cgrp
)
5427 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
5429 struct cgroup_subsys_state
*css
;
5430 struct cgrp_cset_link
*link
;
5433 lockdep_assert_held(&cgroup_mutex
);
5436 * Only migration can raise populated from zero and we're already
5437 * holding cgroup_mutex.
5439 if (cgroup_is_populated(cgrp
))
5443 * Make sure there's no live children. We can't test emptiness of
5444 * ->self.children as dead children linger on it while being
5445 * drained; otherwise, "rmdir parent/child parent" may fail.
5447 if (css_has_online_children(&cgrp
->self
))
5451 * Mark @cgrp and the associated csets dead. The former prevents
5452 * further task migration and child creation by disabling
5453 * cgroup_lock_live_group(). The latter makes the csets ignored by
5454 * the migration path.
5456 cgrp
->self
.flags
&= ~CSS_ONLINE
;
5458 spin_lock_irq(&css_set_lock
);
5459 list_for_each_entry(link
, &cgrp
->cset_links
, cset_link
)
5460 link
->cset
->dead
= true;
5461 spin_unlock_irq(&css_set_lock
);
5463 /* initiate massacre of all css's */
5464 for_each_css(css
, ssid
, cgrp
)
5468 * Remove @cgrp directory along with the base files. @cgrp has an
5469 * extra ref on its kn.
5471 kernfs_remove(cgrp
->kn
);
5473 check_for_release(cgroup_parent(cgrp
));
5475 /* put the base reference */
5476 percpu_ref_kill(&cgrp
->self
.refcnt
);
5481 static int cgroup_rmdir(struct kernfs_node
*kn
)
5483 struct cgroup
*cgrp
;
5486 cgrp
= cgroup_kn_lock_live(kn
, false);
5490 ret
= cgroup_destroy_locked(cgrp
);
5492 cgroup_kn_unlock(kn
);
5496 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
= {
5497 .remount_fs
= cgroup_remount
,
5498 .show_options
= cgroup_show_options
,
5499 .mkdir
= cgroup_mkdir
,
5500 .rmdir
= cgroup_rmdir
,
5501 .rename
= cgroup_rename
,
5502 .show_path
= cgroup_show_path
,
5505 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
, bool early
)
5507 struct cgroup_subsys_state
*css
;
5509 pr_debug("Initializing cgroup subsys %s\n", ss
->name
);
5511 mutex_lock(&cgroup_mutex
);
5513 idr_init(&ss
->css_idr
);
5514 INIT_LIST_HEAD(&ss
->cfts
);
5516 /* Create the root cgroup state for this subsystem */
5517 ss
->root
= &cgrp_dfl_root
;
5518 css
= ss
->css_alloc(cgroup_css(&cgrp_dfl_root
.cgrp
, ss
));
5519 /* We don't handle early failures gracefully */
5520 BUG_ON(IS_ERR(css
));
5521 init_and_link_css(css
, ss
, &cgrp_dfl_root
.cgrp
);
5524 * Root csses are never destroyed and we can't initialize
5525 * percpu_ref during early init. Disable refcnting.
5527 css
->flags
|= CSS_NO_REF
;
5530 /* allocation can't be done safely during early init */
5533 css
->id
= cgroup_idr_alloc(&ss
->css_idr
, css
, 1, 2, GFP_KERNEL
);
5534 BUG_ON(css
->id
< 0);
5537 /* Update the init_css_set to contain a subsys
5538 * pointer to this state - since the subsystem is
5539 * newly registered, all tasks and hence the
5540 * init_css_set is in the subsystem's root cgroup. */
5541 init_css_set
.subsys
[ss
->id
] = css
;
5543 have_fork_callback
|= (bool)ss
->fork
<< ss
->id
;
5544 have_exit_callback
|= (bool)ss
->exit
<< ss
->id
;
5545 have_free_callback
|= (bool)ss
->free
<< ss
->id
;
5546 have_canfork_callback
|= (bool)ss
->can_fork
<< ss
->id
;
5548 /* At system boot, before all subsystems have been
5549 * registered, no tasks have been forked, so we don't
5550 * need to invoke fork callbacks here. */
5551 BUG_ON(!list_empty(&init_task
.tasks
));
5553 BUG_ON(online_css(css
));
5555 mutex_unlock(&cgroup_mutex
);
5559 * cgroup_init_early - cgroup initialization at system boot
5561 * Initialize cgroups at system boot, and initialize any
5562 * subsystems that request early init.
5564 int __init
cgroup_init_early(void)
5566 static struct cgroup_sb_opts __initdata opts
;
5567 struct cgroup_subsys
*ss
;
5570 init_cgroup_root(&cgrp_dfl_root
, &opts
);
5571 cgrp_dfl_root
.cgrp
.self
.flags
|= CSS_NO_REF
;
5573 RCU_INIT_POINTER(init_task
.cgroups
, &init_css_set
);
5575 for_each_subsys(ss
, i
) {
5576 WARN(!ss
->css_alloc
|| !ss
->css_free
|| ss
->name
|| ss
->id
,
5577 "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
5578 i
, cgroup_subsys_name
[i
], ss
->css_alloc
, ss
->css_free
,
5580 WARN(strlen(cgroup_subsys_name
[i
]) > MAX_CGROUP_TYPE_NAMELEN
,
5581 "cgroup_subsys_name %s too long\n", cgroup_subsys_name
[i
]);
5584 ss
->name
= cgroup_subsys_name
[i
];
5585 if (!ss
->legacy_name
)
5586 ss
->legacy_name
= cgroup_subsys_name
[i
];
5589 cgroup_init_subsys(ss
, true);
5594 static u16 cgroup_disable_mask __initdata
;
5597 * cgroup_init - cgroup initialization
5599 * Register cgroup filesystem and /proc file, and initialize
5600 * any subsystems that didn't request early init.
5602 int __init
cgroup_init(void)
5604 struct cgroup_subsys
*ss
;
5607 BUILD_BUG_ON(CGROUP_SUBSYS_COUNT
> 16);
5608 BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem
));
5609 BUG_ON(cgroup_init_cftypes(NULL
, cgroup_dfl_base_files
));
5610 BUG_ON(cgroup_init_cftypes(NULL
, cgroup_legacy_base_files
));
5612 get_user_ns(init_cgroup_ns
.user_ns
);
5614 mutex_lock(&cgroup_mutex
);
5617 * Add init_css_set to the hash table so that dfl_root can link to
5620 hash_add(css_set_table
, &init_css_set
.hlist
,
5621 css_set_hash(init_css_set
.subsys
));
5623 BUG_ON(cgroup_setup_root(&cgrp_dfl_root
, 0));
5625 mutex_unlock(&cgroup_mutex
);
5627 for_each_subsys(ss
, ssid
) {
5628 if (ss
->early_init
) {
5629 struct cgroup_subsys_state
*css
=
5630 init_css_set
.subsys
[ss
->id
];
5632 css
->id
= cgroup_idr_alloc(&ss
->css_idr
, css
, 1, 2,
5634 BUG_ON(css
->id
< 0);
5636 cgroup_init_subsys(ss
, false);
5639 list_add_tail(&init_css_set
.e_cset_node
[ssid
],
5640 &cgrp_dfl_root
.cgrp
.e_csets
[ssid
]);
5643 * Setting dfl_root subsys_mask needs to consider the
5644 * disabled flag and cftype registration needs kmalloc,
5645 * both of which aren't available during early_init.
5647 if (cgroup_disable_mask
& (1 << ssid
)) {
5648 static_branch_disable(cgroup_subsys_enabled_key
[ssid
]);
5649 printk(KERN_INFO
"Disabling %s control group subsystem\n",
5654 if (cgroup_ssid_no_v1(ssid
))
5655 printk(KERN_INFO
"Disabling %s control group subsystem in v1 mounts\n",
5658 cgrp_dfl_root
.subsys_mask
|= 1 << ss
->id
;
5660 if (ss
->implicit_on_dfl
)
5661 cgrp_dfl_implicit_ss_mask
|= 1 << ss
->id
;
5662 else if (!ss
->dfl_cftypes
)
5663 cgrp_dfl_inhibit_ss_mask
|= 1 << ss
->id
;
5665 if (ss
->dfl_cftypes
== ss
->legacy_cftypes
) {
5666 WARN_ON(cgroup_add_cftypes(ss
, ss
->dfl_cftypes
));
5668 WARN_ON(cgroup_add_dfl_cftypes(ss
, ss
->dfl_cftypes
));
5669 WARN_ON(cgroup_add_legacy_cftypes(ss
, ss
->legacy_cftypes
));
5673 ss
->bind(init_css_set
.subsys
[ssid
]);
5676 /* init_css_set.subsys[] has been updated, re-hash */
5677 hash_del(&init_css_set
.hlist
);
5678 hash_add(css_set_table
, &init_css_set
.hlist
,
5679 css_set_hash(init_css_set
.subsys
));
5681 WARN_ON(sysfs_create_mount_point(fs_kobj
, "cgroup"));
5682 WARN_ON(register_filesystem(&cgroup_fs_type
));
5683 WARN_ON(register_filesystem(&cgroup2_fs_type
));
5684 WARN_ON(!proc_create("cgroups", 0, NULL
, &proc_cgroupstats_operations
));
5689 static int __init
cgroup_wq_init(void)
5692 * There isn't much point in executing destruction path in
5693 * parallel. Good chunk is serialized with cgroup_mutex anyway.
5694 * Use 1 for @max_active.
5696 * We would prefer to do this in cgroup_init() above, but that
5697 * is called before init_workqueues(): so leave this until after.
5699 cgroup_destroy_wq
= alloc_workqueue("cgroup_destroy", 0, 1);
5700 BUG_ON(!cgroup_destroy_wq
);
5703 * Used to destroy pidlists and separate to serve as flush domain.
5704 * Cap @max_active to 1 too.
5706 cgroup_pidlist_destroy_wq
= alloc_workqueue("cgroup_pidlist_destroy",
5708 BUG_ON(!cgroup_pidlist_destroy_wq
);
5712 core_initcall(cgroup_wq_init
);
5715 * proc_cgroup_show()
5716 * - Print task's cgroup paths into seq_file, one line for each hierarchy
5717 * - Used for /proc/<pid>/cgroup.
5719 int proc_cgroup_show(struct seq_file
*m
, struct pid_namespace
*ns
,
5720 struct pid
*pid
, struct task_struct
*tsk
)
5724 struct cgroup_root
*root
;
5727 buf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
5731 mutex_lock(&cgroup_mutex
);
5732 spin_lock_irq(&css_set_lock
);
5734 for_each_root(root
) {
5735 struct cgroup_subsys
*ss
;
5736 struct cgroup
*cgrp
;
5737 int ssid
, count
= 0;
5739 if (root
== &cgrp_dfl_root
&& !cgrp_dfl_visible
)
5742 seq_printf(m
, "%d:", root
->hierarchy_id
);
5743 if (root
!= &cgrp_dfl_root
)
5744 for_each_subsys(ss
, ssid
)
5745 if (root
->subsys_mask
& (1 << ssid
))
5746 seq_printf(m
, "%s%s", count
++ ? "," : "",
5748 if (strlen(root
->name
))
5749 seq_printf(m
, "%sname=%s", count
? "," : "",
5753 cgrp
= task_cgroup_from_root(tsk
, root
);
5756 * On traditional hierarchies, all zombie tasks show up as
5757 * belonging to the root cgroup. On the default hierarchy,
5758 * while a zombie doesn't show up in "cgroup.procs" and
5759 * thus can't be migrated, its /proc/PID/cgroup keeps
5760 * reporting the cgroup it belonged to before exiting. If
5761 * the cgroup is removed before the zombie is reaped,
5762 * " (deleted)" is appended to the cgroup path.
5764 if (cgroup_on_dfl(cgrp
) || !(tsk
->flags
& PF_EXITING
)) {
5765 path
= cgroup_path_ns_locked(cgrp
, buf
, PATH_MAX
,
5766 current
->nsproxy
->cgroup_ns
);
5768 retval
= -ENAMETOOLONG
;
5777 if (cgroup_on_dfl(cgrp
) && cgroup_is_dead(cgrp
))
5778 seq_puts(m
, " (deleted)\n");
5785 spin_unlock_irq(&css_set_lock
);
5786 mutex_unlock(&cgroup_mutex
);
5792 /* Display information about each subsystem and each hierarchy */
5793 static int proc_cgroupstats_show(struct seq_file
*m
, void *v
)
5795 struct cgroup_subsys
*ss
;
5798 seq_puts(m
, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
5800 * ideally we don't want subsystems moving around while we do this.
5801 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
5802 * subsys/hierarchy state.
5804 mutex_lock(&cgroup_mutex
);
5806 for_each_subsys(ss
, i
)
5807 seq_printf(m
, "%s\t%d\t%d\t%d\n",
5808 ss
->legacy_name
, ss
->root
->hierarchy_id
,
5809 atomic_read(&ss
->root
->nr_cgrps
),
5810 cgroup_ssid_enabled(i
));
5812 mutex_unlock(&cgroup_mutex
);
5816 static int cgroupstats_open(struct inode
*inode
, struct file
*file
)
5818 return single_open(file
, proc_cgroupstats_show
, NULL
);
5821 static const struct file_operations proc_cgroupstats_operations
= {
5822 .open
= cgroupstats_open
,
5824 .llseek
= seq_lseek
,
5825 .release
= single_release
,
5829 * cgroup_fork - initialize cgroup related fields during copy_process()
5830 * @child: pointer to task_struct of forking parent process.
5832 * A task is associated with the init_css_set until cgroup_post_fork()
5833 * attaches it to the parent's css_set. Empty cg_list indicates that
5834 * @child isn't holding reference to its css_set.
5836 void cgroup_fork(struct task_struct
*child
)
5838 RCU_INIT_POINTER(child
->cgroups
, &init_css_set
);
5839 INIT_LIST_HEAD(&child
->cg_list
);
5843 * cgroup_can_fork - called on a new task before the process is exposed
5844 * @child: the task in question.
5846 * This calls the subsystem can_fork() callbacks. If the can_fork() callback
5847 * returns an error, the fork aborts with that error code. This allows for
5848 * a cgroup subsystem to conditionally allow or deny new forks.
5850 int cgroup_can_fork(struct task_struct
*child
)
5852 struct cgroup_subsys
*ss
;
5855 do_each_subsys_mask(ss
, i
, have_canfork_callback
) {
5856 ret
= ss
->can_fork(child
);
5859 } while_each_subsys_mask();
5864 for_each_subsys(ss
, j
) {
5867 if (ss
->cancel_fork
)
5868 ss
->cancel_fork(child
);
5875 * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
5876 * @child: the task in question
5878 * This calls the cancel_fork() callbacks if a fork failed *after*
5879 * cgroup_can_fork() succeded.
5881 void cgroup_cancel_fork(struct task_struct
*child
)
5883 struct cgroup_subsys
*ss
;
5886 for_each_subsys(ss
, i
)
5887 if (ss
->cancel_fork
)
5888 ss
->cancel_fork(child
);
5892 * cgroup_post_fork - called on a new task after adding it to the task list
5893 * @child: the task in question
5895 * Adds the task to the list running through its css_set if necessary and
5896 * call the subsystem fork() callbacks. Has to be after the task is
5897 * visible on the task list in case we race with the first call to
5898 * cgroup_task_iter_start() - to guarantee that the new task ends up on its
5901 void cgroup_post_fork(struct task_struct
*child
)
5903 struct cgroup_subsys
*ss
;
5907 * This may race against cgroup_enable_task_cg_lists(). As that
5908 * function sets use_task_css_set_links before grabbing
5909 * tasklist_lock and we just went through tasklist_lock to add
5910 * @child, it's guaranteed that either we see the set
5911 * use_task_css_set_links or cgroup_enable_task_cg_lists() sees
5912 * @child during its iteration.
5914 * If we won the race, @child is associated with %current's
5915 * css_set. Grabbing css_set_lock guarantees both that the
5916 * association is stable, and, on completion of the parent's
5917 * migration, @child is visible in the source of migration or
5918 * already in the destination cgroup. This guarantee is necessary
5919 * when implementing operations which need to migrate all tasks of
5920 * a cgroup to another.
5922 * Note that if we lose to cgroup_enable_task_cg_lists(), @child
5923 * will remain in init_css_set. This is safe because all tasks are
5924 * in the init_css_set before cg_links is enabled and there's no
5925 * operation which transfers all tasks out of init_css_set.
5927 if (use_task_css_set_links
) {
5928 struct css_set
*cset
;
5930 spin_lock_irq(&css_set_lock
);
5931 cset
= task_css_set(current
);
5932 if (list_empty(&child
->cg_list
)) {
5934 css_set_move_task(child
, NULL
, cset
, false);
5936 spin_unlock_irq(&css_set_lock
);
5940 * Call ss->fork(). This must happen after @child is linked on
5941 * css_set; otherwise, @child might change state between ->fork()
5942 * and addition to css_set.
5944 do_each_subsys_mask(ss
, i
, have_fork_callback
) {
5946 } while_each_subsys_mask();
5950 * cgroup_exit - detach cgroup from exiting task
5951 * @tsk: pointer to task_struct of exiting process
5953 * Description: Detach cgroup from @tsk and release it.
5955 * Note that cgroups marked notify_on_release force every task in
5956 * them to take the global cgroup_mutex mutex when exiting.
5957 * This could impact scaling on very large systems. Be reluctant to
5958 * use notify_on_release cgroups where very high task exit scaling
5959 * is required on large systems.
5961 * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
5962 * call cgroup_exit() while the task is still competent to handle
5963 * notify_on_release(), then leave the task attached to the root cgroup in
5964 * each hierarchy for the remainder of its exit. No need to bother with
5965 * init_css_set refcnting. init_css_set never goes away and we can't race
5966 * with migration path - PF_EXITING is visible to migration path.
5968 void cgroup_exit(struct task_struct
*tsk
)
5970 struct cgroup_subsys
*ss
;
5971 struct css_set
*cset
;
5975 * Unlink from @tsk from its css_set. As migration path can't race
5976 * with us, we can check css_set and cg_list without synchronization.
5978 cset
= task_css_set(tsk
);
5980 if (!list_empty(&tsk
->cg_list
)) {
5981 spin_lock_irq(&css_set_lock
);
5982 css_set_move_task(tsk
, cset
, NULL
, false);
5983 spin_unlock_irq(&css_set_lock
);
5988 /* see cgroup_post_fork() for details */
5989 do_each_subsys_mask(ss
, i
, have_exit_callback
) {
5991 } while_each_subsys_mask();
5994 void cgroup_free(struct task_struct
*task
)
5996 struct css_set
*cset
= task_css_set(task
);
5997 struct cgroup_subsys
*ss
;
6000 do_each_subsys_mask(ss
, ssid
, have_free_callback
) {
6002 } while_each_subsys_mask();
6007 static void check_for_release(struct cgroup
*cgrp
)
6009 if (notify_on_release(cgrp
) && !cgroup_is_populated(cgrp
) &&
6010 !css_has_online_children(&cgrp
->self
) && !cgroup_is_dead(cgrp
))
6011 schedule_work(&cgrp
->release_agent_work
);
6015 * Notify userspace when a cgroup is released, by running the
6016 * configured release agent with the name of the cgroup (path
6017 * relative to the root of cgroup file system) as the argument.
6019 * Most likely, this user command will try to rmdir this cgroup.
6021 * This races with the possibility that some other task will be
6022 * attached to this cgroup before it is removed, or that some other
6023 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
6024 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
6025 * unused, and this cgroup will be reprieved from its death sentence,
6026 * to continue to serve a useful existence. Next time it's released,
6027 * we will get notified again, if it still has 'notify_on_release' set.
6029 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
6030 * means only wait until the task is successfully execve()'d. The
6031 * separate release agent task is forked by call_usermodehelper(),
6032 * then control in this thread returns here, without waiting for the
6033 * release agent task. We don't bother to wait because the caller of
6034 * this routine has no use for the exit status of the release agent
6035 * task, so no sense holding our caller up for that.
6037 static void cgroup_release_agent(struct work_struct
*work
)
6039 struct cgroup
*cgrp
=
6040 container_of(work
, struct cgroup
, release_agent_work
);
6041 char *pathbuf
= NULL
, *agentbuf
= NULL
, *path
;
6042 char *argv
[3], *envp
[3];
6044 mutex_lock(&cgroup_mutex
);
6046 pathbuf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
6047 agentbuf
= kstrdup(cgrp
->root
->release_agent_path
, GFP_KERNEL
);
6048 if (!pathbuf
|| !agentbuf
)
6051 spin_lock_irq(&css_set_lock
);
6052 path
= cgroup_path_ns_locked(cgrp
, pathbuf
, PATH_MAX
, &init_cgroup_ns
);
6053 spin_unlock_irq(&css_set_lock
);
6061 /* minimal command environment */
6063 envp
[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
6066 mutex_unlock(&cgroup_mutex
);
6067 call_usermodehelper(argv
[0], argv
, envp
, UMH_WAIT_EXEC
);
6070 mutex_unlock(&cgroup_mutex
);
6076 static int __init
cgroup_disable(char *str
)
6078 struct cgroup_subsys
*ss
;
6082 while ((token
= strsep(&str
, ",")) != NULL
) {
6086 for_each_subsys(ss
, i
) {
6087 if (strcmp(token
, ss
->name
) &&
6088 strcmp(token
, ss
->legacy_name
))
6090 cgroup_disable_mask
|= 1 << i
;
6095 __setup("cgroup_disable=", cgroup_disable
);
6097 static int __init
cgroup_no_v1(char *str
)
6099 struct cgroup_subsys
*ss
;
6103 while ((token
= strsep(&str
, ",")) != NULL
) {
6107 if (!strcmp(token
, "all")) {
6108 cgroup_no_v1_mask
= U16_MAX
;
6112 for_each_subsys(ss
, i
) {
6113 if (strcmp(token
, ss
->name
) &&
6114 strcmp(token
, ss
->legacy_name
))
6117 cgroup_no_v1_mask
|= 1 << i
;
6122 __setup("cgroup_no_v1=", cgroup_no_v1
);
6125 * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
6126 * @dentry: directory dentry of interest
6127 * @ss: subsystem of interest
6129 * If @dentry is a directory for a cgroup which has @ss enabled on it, try
6130 * to get the corresponding css and return it. If such css doesn't exist
6131 * or can't be pinned, an ERR_PTR value is returned.
6133 struct cgroup_subsys_state
*css_tryget_online_from_dir(struct dentry
*dentry
,
6134 struct cgroup_subsys
*ss
)
6136 struct kernfs_node
*kn
= kernfs_node_from_dentry(dentry
);
6137 struct file_system_type
*s_type
= dentry
->d_sb
->s_type
;
6138 struct cgroup_subsys_state
*css
= NULL
;
6139 struct cgroup
*cgrp
;
6141 /* is @dentry a cgroup dir? */
6142 if ((s_type
!= &cgroup_fs_type
&& s_type
!= &cgroup2_fs_type
) ||
6143 !kn
|| kernfs_type(kn
) != KERNFS_DIR
)
6144 return ERR_PTR(-EBADF
);
6149 * This path doesn't originate from kernfs and @kn could already
6150 * have been or be removed at any point. @kn->priv is RCU
6151 * protected for this access. See css_release_work_fn() for details.
6153 cgrp
= rcu_dereference(kn
->priv
);
6155 css
= cgroup_css(cgrp
, ss
);
6157 if (!css
|| !css_tryget_online(css
))
6158 css
= ERR_PTR(-ENOENT
);
6165 * css_from_id - lookup css by id
6166 * @id: the cgroup id
6167 * @ss: cgroup subsys to be looked into
6169 * Returns the css if there's valid one with @id, otherwise returns NULL.
6170 * Should be called under rcu_read_lock().
6172 struct cgroup_subsys_state
*css_from_id(int id
, struct cgroup_subsys
*ss
)
6174 WARN_ON_ONCE(!rcu_read_lock_held());
6175 return id
> 0 ? idr_find(&ss
->css_idr
, id
) : NULL
;
6179 * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
6180 * @path: path on the default hierarchy
6182 * Find the cgroup at @path on the default hierarchy, increment its
6183 * reference count and return it. Returns pointer to the found cgroup on
6184 * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR)
6185 * if @path points to a non-directory.
6187 struct cgroup
*cgroup_get_from_path(const char *path
)
6189 struct kernfs_node
*kn
;
6190 struct cgroup
*cgrp
;
6192 mutex_lock(&cgroup_mutex
);
6194 kn
= kernfs_walk_and_get(cgrp_dfl_root
.cgrp
.kn
, path
);
6196 if (kernfs_type(kn
) == KERNFS_DIR
) {
6200 cgrp
= ERR_PTR(-ENOTDIR
);
6204 cgrp
= ERR_PTR(-ENOENT
);
6207 mutex_unlock(&cgroup_mutex
);
6210 EXPORT_SYMBOL_GPL(cgroup_get_from_path
);
6213 * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
6214 * definition in cgroup-defs.h.
6216 #ifdef CONFIG_SOCK_CGROUP_DATA
6218 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
6220 DEFINE_SPINLOCK(cgroup_sk_update_lock
);
6221 static bool cgroup_sk_alloc_disabled __read_mostly
;
6223 void cgroup_sk_alloc_disable(void)
6225 if (cgroup_sk_alloc_disabled
)
6227 pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
6228 cgroup_sk_alloc_disabled
= true;
6233 #define cgroup_sk_alloc_disabled false
6237 void cgroup_sk_alloc(struct sock_cgroup_data
*skcd
)
6239 if (cgroup_sk_alloc_disabled
)
6245 struct css_set
*cset
;
6247 cset
= task_css_set(current
);
6248 if (likely(cgroup_tryget(cset
->dfl_cgrp
))) {
6249 skcd
->val
= (unsigned long)cset
->dfl_cgrp
;
6258 void cgroup_sk_free(struct sock_cgroup_data
*skcd
)
6260 cgroup_put(sock_cgroup_ptr(skcd
));
6263 #endif /* CONFIG_SOCK_CGROUP_DATA */
6265 /* cgroup namespaces */
6267 static struct cgroup_namespace
*alloc_cgroup_ns(void)
6269 struct cgroup_namespace
*new_ns
;
6272 new_ns
= kzalloc(sizeof(struct cgroup_namespace
), GFP_KERNEL
);
6274 return ERR_PTR(-ENOMEM
);
6275 ret
= ns_alloc_inum(&new_ns
->ns
);
6278 return ERR_PTR(ret
);
6280 atomic_set(&new_ns
->count
, 1);
6281 new_ns
->ns
.ops
= &cgroupns_operations
;
6285 void free_cgroup_ns(struct cgroup_namespace
*ns
)
6287 put_css_set(ns
->root_cset
);
6288 put_user_ns(ns
->user_ns
);
6289 ns_free_inum(&ns
->ns
);
6292 EXPORT_SYMBOL(free_cgroup_ns
);
6294 struct cgroup_namespace
*copy_cgroup_ns(unsigned long flags
,
6295 struct user_namespace
*user_ns
,
6296 struct cgroup_namespace
*old_ns
)
6298 struct cgroup_namespace
*new_ns
;
6299 struct css_set
*cset
;
6303 if (!(flags
& CLONE_NEWCGROUP
)) {
6304 get_cgroup_ns(old_ns
);
6308 /* Allow only sysadmin to create cgroup namespace. */
6309 if (!ns_capable(user_ns
, CAP_SYS_ADMIN
))
6310 return ERR_PTR(-EPERM
);
6312 mutex_lock(&cgroup_mutex
);
6313 spin_lock_irq(&css_set_lock
);
6315 cset
= task_css_set(current
);
6318 spin_unlock_irq(&css_set_lock
);
6319 mutex_unlock(&cgroup_mutex
);
6321 new_ns
= alloc_cgroup_ns();
6322 if (IS_ERR(new_ns
)) {
6327 new_ns
->user_ns
= get_user_ns(user_ns
);
6328 new_ns
->root_cset
= cset
;
6333 static inline struct cgroup_namespace
*to_cg_ns(struct ns_common
*ns
)
6335 return container_of(ns
, struct cgroup_namespace
, ns
);
6338 static int cgroupns_install(struct nsproxy
*nsproxy
, struct ns_common
*ns
)
6340 struct cgroup_namespace
*cgroup_ns
= to_cg_ns(ns
);
6342 if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN
) ||
6343 !ns_capable(cgroup_ns
->user_ns
, CAP_SYS_ADMIN
))
6346 /* Don't need to do anything if we are attaching to our own cgroupns. */
6347 if (cgroup_ns
== nsproxy
->cgroup_ns
)
6350 get_cgroup_ns(cgroup_ns
);
6351 put_cgroup_ns(nsproxy
->cgroup_ns
);
6352 nsproxy
->cgroup_ns
= cgroup_ns
;
6357 static struct ns_common
*cgroupns_get(struct task_struct
*task
)
6359 struct cgroup_namespace
*ns
= NULL
;
6360 struct nsproxy
*nsproxy
;
6363 nsproxy
= task
->nsproxy
;
6365 ns
= nsproxy
->cgroup_ns
;
6370 return ns
? &ns
->ns
: NULL
;
6373 static void cgroupns_put(struct ns_common
*ns
)
6375 put_cgroup_ns(to_cg_ns(ns
));
6378 const struct proc_ns_operations cgroupns_operations
= {
6380 .type
= CLONE_NEWCGROUP
,
6381 .get
= cgroupns_get
,
6382 .put
= cgroupns_put
,
6383 .install
= cgroupns_install
,
6386 static __init
int cgroup_namespaces_init(void)
6390 subsys_initcall(cgroup_namespaces_init
);
6392 #ifdef CONFIG_CGROUP_DEBUG
6393 static struct cgroup_subsys_state
*
6394 debug_css_alloc(struct cgroup_subsys_state
*parent_css
)
6396 struct cgroup_subsys_state
*css
= kzalloc(sizeof(*css
), GFP_KERNEL
);
6399 return ERR_PTR(-ENOMEM
);
6404 static void debug_css_free(struct cgroup_subsys_state
*css
)
6409 static u64
debug_taskcount_read(struct cgroup_subsys_state
*css
,
6412 return cgroup_task_count(css
->cgroup
);
6415 static u64
current_css_set_read(struct cgroup_subsys_state
*css
,
6418 return (u64
)(unsigned long)current
->cgroups
;
6421 static u64
current_css_set_refcount_read(struct cgroup_subsys_state
*css
,
6427 count
= atomic_read(&task_css_set(current
)->refcount
);
6432 static int current_css_set_cg_links_read(struct seq_file
*seq
, void *v
)
6434 struct cgrp_cset_link
*link
;
6435 struct css_set
*cset
;
6438 name_buf
= kmalloc(NAME_MAX
+ 1, GFP_KERNEL
);
6442 spin_lock_irq(&css_set_lock
);
6444 cset
= rcu_dereference(current
->cgroups
);
6445 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
6446 struct cgroup
*c
= link
->cgrp
;
6448 cgroup_name(c
, name_buf
, NAME_MAX
+ 1);
6449 seq_printf(seq
, "Root %d group %s\n",
6450 c
->root
->hierarchy_id
, name_buf
);
6453 spin_unlock_irq(&css_set_lock
);
6458 #define MAX_TASKS_SHOWN_PER_CSS 25
6459 static int cgroup_css_links_read(struct seq_file
*seq
, void *v
)
6461 struct cgroup_subsys_state
*css
= seq_css(seq
);
6462 struct cgrp_cset_link
*link
;
6464 spin_lock_irq(&css_set_lock
);
6465 list_for_each_entry(link
, &css
->cgroup
->cset_links
, cset_link
) {
6466 struct css_set
*cset
= link
->cset
;
6467 struct task_struct
*task
;
6470 seq_printf(seq
, "css_set %p\n", cset
);
6472 list_for_each_entry(task
, &cset
->tasks
, cg_list
) {
6473 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
)
6475 seq_printf(seq
, " task %d\n", task_pid_vnr(task
));
6478 list_for_each_entry(task
, &cset
->mg_tasks
, cg_list
) {
6479 if (count
++ > MAX_TASKS_SHOWN_PER_CSS
)
6481 seq_printf(seq
, " task %d\n", task_pid_vnr(task
));
6485 seq_puts(seq
, " ...\n");
6487 spin_unlock_irq(&css_set_lock
);
6491 static u64
releasable_read(struct cgroup_subsys_state
*css
, struct cftype
*cft
)
6493 return (!cgroup_is_populated(css
->cgroup
) &&
6494 !css_has_online_children(&css
->cgroup
->self
));
6497 static struct cftype debug_files
[] = {
6499 .name
= "taskcount",
6500 .read_u64
= debug_taskcount_read
,
6504 .name
= "current_css_set",
6505 .read_u64
= current_css_set_read
,
6509 .name
= "current_css_set_refcount",
6510 .read_u64
= current_css_set_refcount_read
,
6514 .name
= "current_css_set_cg_links",
6515 .seq_show
= current_css_set_cg_links_read
,
6519 .name
= "cgroup_css_links",
6520 .seq_show
= cgroup_css_links_read
,
6524 .name
= "releasable",
6525 .read_u64
= releasable_read
,
6531 struct cgroup_subsys debug_cgrp_subsys
= {
6532 .css_alloc
= debug_css_alloc
,
6533 .css_free
= debug_css_free
,
6534 .legacy_cftypes
= debug_files
,
6536 #endif /* CONFIG_CGROUP_DEBUG */