1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_CGROUP_H
3 #define _LINUX_CGROUP_H
7 * Copyright (C) 2003 BULL SA
8 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
12 #include <linux/sched.h>
13 #include <linux/cpumask.h>
14 #include <linux/nodemask.h>
15 #include <linux/rculist.h>
16 #include <linux/cgroupstats.h>
18 #include <linux/seq_file.h>
19 #include <linux/kernfs.h>
20 #include <linux/jump_label.h>
21 #include <linux/types.h>
22 #include <linux/ns_common.h>
23 #include <linux/nsproxy.h>
24 #include <linux/user_namespace.h>
25 #include <linux/refcount.h>
27 #include <linux/cgroup-defs.h>
32 * All weight knobs on the default hierarhcy should use the following min,
33 * default and max values. The default value is the logarithmic center of
34 * MIN and MAX and allows 100x to be expressed in both directions.
36 #define CGROUP_WEIGHT_MIN 1
37 #define CGROUP_WEIGHT_DFL 100
38 #define CGROUP_WEIGHT_MAX 10000
40 /* walk only threadgroup leaders */
41 #define CSS_TASK_ITER_PROCS (1U << 0)
42 /* walk all threaded css_sets in the domain */
43 #define CSS_TASK_ITER_THREADED (1U << 1)
46 #define CSS_TASK_ITER_SKIPPED (1U << 16)
48 /* a css_task_iter should be treated as an opaque object */
49 struct css_task_iter {
50 struct cgroup_subsys *ss;
53 struct list_head *cset_pos;
54 struct list_head *cset_head;
56 struct list_head *tcset_pos;
57 struct list_head *tcset_head;
59 struct list_head *task_pos;
60 struct list_head *tasks_head;
61 struct list_head *mg_tasks_head;
62 struct list_head *dying_tasks_head;
64 struct list_head *cur_tasks_head;
65 struct css_set *cur_cset;
66 struct css_set *cur_dcset;
67 struct task_struct *cur_task;
68 struct list_head iters_node; /* css_set->task_iters */
71 extern struct cgroup_root cgrp_dfl_root;
72 extern struct css_set init_css_set;
74 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
75 #include <linux/cgroup_subsys.h>
79 extern struct static_key_true _x ## _cgrp_subsys_enabled_key; \
80 extern struct static_key_true _x ## _cgrp_subsys_on_dfl_key;
81 #include <linux/cgroup_subsys.h>
85 * cgroup_subsys_enabled - fast test on whether a subsys is enabled
86 * @ss: subsystem in question
88 #define cgroup_subsys_enabled(ss) \
89 static_branch_likely(&ss ## _enabled_key)
92 * cgroup_subsys_on_dfl - fast test on whether a subsys is on default hierarchy
93 * @ss: subsystem in question
95 #define cgroup_subsys_on_dfl(ss) \
96 static_branch_likely(&ss ## _on_dfl_key)
98 bool css_has_online_children(struct cgroup_subsys_state *css);
99 struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
100 struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup,
101 struct cgroup_subsys *ss);
102 struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
103 struct cgroup_subsys *ss);
105 struct cgroup *cgroup_get_from_path(const char *path);
106 struct cgroup *cgroup_get_from_fd(int fd);
108 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
109 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
111 int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
112 int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
113 int cgroup_rm_cftypes(struct cftype *cfts);
114 void cgroup_file_notify(struct cgroup_file *cfile);
116 int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
117 int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry);
118 int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
119 struct pid *pid, struct task_struct *tsk);
121 void cgroup_fork(struct task_struct *p);
122 extern int cgroup_can_fork(struct task_struct *p);
123 extern void cgroup_cancel_fork(struct task_struct *p);
124 extern void cgroup_post_fork(struct task_struct *p);
125 void cgroup_exit(struct task_struct *p);
126 void cgroup_release(struct task_struct *p);
127 void cgroup_free(struct task_struct *p);
129 int cgroup_init_early(void);
130 int cgroup_init(void);
133 * Iteration helpers and macros.
136 struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
137 struct cgroup_subsys_state *parent);
138 struct cgroup_subsys_state *css_next_descendant_pre(struct cgroup_subsys_state *pos,
139 struct cgroup_subsys_state *css);
140 struct cgroup_subsys_state *css_rightmost_descendant(struct cgroup_subsys_state *pos);
141 struct cgroup_subsys_state *css_next_descendant_post(struct cgroup_subsys_state *pos,
142 struct cgroup_subsys_state *css);
144 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
145 struct cgroup_subsys_state **dst_cssp);
146 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
147 struct cgroup_subsys_state **dst_cssp);
149 void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
150 struct css_task_iter *it);
151 struct task_struct *css_task_iter_next(struct css_task_iter *it);
152 void css_task_iter_end(struct css_task_iter *it);
155 * css_for_each_child - iterate through children of a css
156 * @pos: the css * to use as the loop cursor
157 * @parent: css whose children to walk
159 * Walk @parent's children. Must be called under rcu_read_lock().
161 * If a subsystem synchronizes ->css_online() and the start of iteration, a
162 * css which finished ->css_online() is guaranteed to be visible in the
163 * future iterations and will stay visible until the last reference is put.
164 * A css which hasn't finished ->css_online() or already finished
165 * ->css_offline() may show up during traversal. It's each subsystem's
166 * responsibility to synchronize against on/offlining.
168 * It is allowed to temporarily drop RCU read lock during iteration. The
169 * caller is responsible for ensuring that @pos remains accessible until
170 * the start of the next iteration by, for example, bumping the css refcnt.
172 #define css_for_each_child(pos, parent) \
173 for ((pos) = css_next_child(NULL, (parent)); (pos); \
174 (pos) = css_next_child((pos), (parent)))
177 * css_for_each_descendant_pre - pre-order walk of a css's descendants
178 * @pos: the css * to use as the loop cursor
179 * @root: css whose descendants to walk
181 * Walk @root's descendants. @root is included in the iteration and the
182 * first node to be visited. Must be called under rcu_read_lock().
184 * If a subsystem synchronizes ->css_online() and the start of iteration, a
185 * css which finished ->css_online() is guaranteed to be visible in the
186 * future iterations and will stay visible until the last reference is put.
187 * A css which hasn't finished ->css_online() or already finished
188 * ->css_offline() may show up during traversal. It's each subsystem's
189 * responsibility to synchronize against on/offlining.
191 * For example, the following guarantees that a descendant can't escape
192 * state updates of its ancestors.
196 * Lock @css's parent and @css;
197 * Inherit state from the parent;
201 * my_update_state(@css)
203 * css_for_each_descendant_pre(@pos, @css) {
206 * Update @css's state;
208 * Verify @pos is alive and inherit state from its parent;
213 * As long as the inheriting step, including checking the parent state, is
214 * enclosed inside @pos locking, double-locking the parent isn't necessary
215 * while inheriting. The state update to the parent is guaranteed to be
216 * visible by walking order and, as long as inheriting operations to the
217 * same @pos are atomic to each other, multiple updates racing each other
218 * still result in the correct state. It's guaranateed that at least one
219 * inheritance happens for any css after the latest update to its parent.
221 * If checking parent's state requires locking the parent, each inheriting
222 * iteration should lock and unlock both @pos->parent and @pos.
224 * Alternatively, a subsystem may choose to use a single global lock to
225 * synchronize ->css_online() and ->css_offline() against tree-walking
228 * It is allowed to temporarily drop RCU read lock during iteration. The
229 * caller is responsible for ensuring that @pos remains accessible until
230 * the start of the next iteration by, for example, bumping the css refcnt.
232 #define css_for_each_descendant_pre(pos, css) \
233 for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \
234 (pos) = css_next_descendant_pre((pos), (css)))
237 * css_for_each_descendant_post - post-order walk of a css's descendants
238 * @pos: the css * to use as the loop cursor
239 * @css: css whose descendants to walk
241 * Similar to css_for_each_descendant_pre() but performs post-order
242 * traversal instead. @root is included in the iteration and the last
243 * node to be visited.
245 * If a subsystem synchronizes ->css_online() and the start of iteration, a
246 * css which finished ->css_online() is guaranteed to be visible in the
247 * future iterations and will stay visible until the last reference is put.
248 * A css which hasn't finished ->css_online() or already finished
249 * ->css_offline() may show up during traversal. It's each subsystem's
250 * responsibility to synchronize against on/offlining.
252 * Note that the walk visibility guarantee example described in pre-order
253 * walk doesn't apply the same to post-order walks.
255 #define css_for_each_descendant_post(pos, css) \
256 for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
257 (pos) = css_next_descendant_post((pos), (css)))
260 * cgroup_taskset_for_each - iterate cgroup_taskset
261 * @task: the loop cursor
262 * @dst_css: the destination css
263 * @tset: taskset to iterate
265 * @tset may contain multiple tasks and they may belong to multiple
268 * On the v2 hierarchy, there may be tasks from multiple processes and they
269 * may not share the source or destination csses.
271 * On traditional hierarchies, when there are multiple tasks in @tset, if a
272 * task of a process is in @tset, all tasks of the process are in @tset.
273 * Also, all are guaranteed to share the same source and destination csses.
275 * Iteration is not in any specific order.
277 #define cgroup_taskset_for_each(task, dst_css, tset) \
278 for ((task) = cgroup_taskset_first((tset), &(dst_css)); \
280 (task) = cgroup_taskset_next((tset), &(dst_css)))
283 * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset
284 * @leader: the loop cursor
285 * @dst_css: the destination css
286 * @tset: taskset to iterate
288 * Iterate threadgroup leaders of @tset. For single-task migrations, @tset
289 * may not contain any.
291 #define cgroup_taskset_for_each_leader(leader, dst_css, tset) \
292 for ((leader) = cgroup_taskset_first((tset), &(dst_css)); \
294 (leader) = cgroup_taskset_next((tset), &(dst_css))) \
295 if ((leader) != (leader)->group_leader) \
304 * css_get - obtain a reference on the specified css
307 * The caller must already have a reference.
309 static inline void css_get(struct cgroup_subsys_state *css)
311 if (!(css->flags & CSS_NO_REF))
312 percpu_ref_get(&css->refcnt);
316 * css_get_many - obtain references on the specified css
318 * @n: number of references to get
320 * The caller must already have a reference.
322 static inline void css_get_many(struct cgroup_subsys_state *css, unsigned int n)
324 if (!(css->flags & CSS_NO_REF))
325 percpu_ref_get_many(&css->refcnt, n);
329 * css_tryget - try to obtain a reference on the specified css
332 * Obtain a reference on @css unless it already has reached zero and is
333 * being released. This function doesn't care whether @css is on or
334 * offline. The caller naturally needs to ensure that @css is accessible
335 * but doesn't have to be holding a reference on it - IOW, RCU protected
336 * access is good enough for this function. Returns %true if a reference
337 * count was successfully obtained; %false otherwise.
339 static inline bool css_tryget(struct cgroup_subsys_state *css)
341 if (!(css->flags & CSS_NO_REF))
342 return percpu_ref_tryget(&css->refcnt);
347 * css_tryget_online - try to obtain a reference on the specified css if online
350 * Obtain a reference on @css if it's online. The caller naturally needs
351 * to ensure that @css is accessible but doesn't have to be holding a
352 * reference on it - IOW, RCU protected access is good enough for this
353 * function. Returns %true if a reference count was successfully obtained;
356 static inline bool css_tryget_online(struct cgroup_subsys_state *css)
358 if (!(css->flags & CSS_NO_REF))
359 return percpu_ref_tryget_live(&css->refcnt);
364 * css_is_dying - test whether the specified css is dying
367 * Test whether @css is in the process of offlining or already offline. In
368 * most cases, ->css_online() and ->css_offline() callbacks should be
369 * enough; however, the actual offline operations are RCU delayed and this
370 * test returns %true also when @css is scheduled to be offlined.
372 * This is useful, for example, when the use case requires synchronous
373 * behavior with respect to cgroup removal. cgroup removal schedules css
374 * offlining but the css can seem alive while the operation is being
375 * delayed. If the delay affects user visible semantics, this test can be
376 * used to resolve the situation.
378 static inline bool css_is_dying(struct cgroup_subsys_state *css)
380 return !(css->flags & CSS_NO_REF) && percpu_ref_is_dying(&css->refcnt);
384 * css_put - put a css reference
387 * Put a reference obtained via css_get() and css_tryget_online().
389 static inline void css_put(struct cgroup_subsys_state *css)
391 if (!(css->flags & CSS_NO_REF))
392 percpu_ref_put(&css->refcnt);
396 * css_put_many - put css references
398 * @n: number of references to put
400 * Put references obtained via css_get() and css_tryget_online().
402 static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n)
404 if (!(css->flags & CSS_NO_REF))
405 percpu_ref_put_many(&css->refcnt, n);
408 static inline void cgroup_get(struct cgroup *cgrp)
410 css_get(&cgrp->self);
413 static inline bool cgroup_tryget(struct cgroup *cgrp)
415 return css_tryget(&cgrp->self);
418 static inline void cgroup_put(struct cgroup *cgrp)
420 css_put(&cgrp->self);
424 * task_css_set_check - obtain a task's css_set with extra access conditions
425 * @task: the task to obtain css_set for
426 * @__c: extra condition expression to be passed to rcu_dereference_check()
428 * A task's css_set is RCU protected, initialized and exited while holding
429 * task_lock(), and can only be modified while holding both cgroup_mutex
430 * and task_lock() while the task is alive. This macro verifies that the
431 * caller is inside proper critical section and returns @task's css_set.
433 * The caller can also specify additional allowed conditions via @__c, such
434 * as locks used during the cgroup_subsys::attach() methods.
436 #ifdef CONFIG_PROVE_RCU
437 extern struct mutex cgroup_mutex;
438 extern spinlock_t css_set_lock;
439 #define task_css_set_check(task, __c) \
440 rcu_dereference_check((task)->cgroups, \
441 lockdep_is_held(&cgroup_mutex) || \
442 lockdep_is_held(&css_set_lock) || \
443 ((task)->flags & PF_EXITING) || (__c))
445 #define task_css_set_check(task, __c) \
446 rcu_dereference((task)->cgroups)
450 * task_css_check - obtain css for (task, subsys) w/ extra access conds
451 * @task: the target task
452 * @subsys_id: the target subsystem ID
453 * @__c: extra condition expression to be passed to rcu_dereference_check()
455 * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The
456 * synchronization rules are the same as task_css_set_check().
458 #define task_css_check(task, subsys_id, __c) \
459 task_css_set_check((task), (__c))->subsys[(subsys_id)]
462 * task_css_set - obtain a task's css_set
463 * @task: the task to obtain css_set for
465 * See task_css_set_check().
467 static inline struct css_set *task_css_set(struct task_struct *task)
469 return task_css_set_check(task, false);
473 * task_css - obtain css for (task, subsys)
474 * @task: the target task
475 * @subsys_id: the target subsystem ID
477 * See task_css_check().
479 static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
482 return task_css_check(task, subsys_id, false);
486 * task_get_css - find and get the css for (task, subsys)
487 * @task: the target task
488 * @subsys_id: the target subsystem ID
490 * Find the css for the (@task, @subsys_id) combination, increment a
491 * reference on and return it. This function is guaranteed to return a
492 * valid css. The returned css may already have been offlined.
494 static inline struct cgroup_subsys_state *
495 task_get_css(struct task_struct *task, int subsys_id)
497 struct cgroup_subsys_state *css;
501 css = task_css(task, subsys_id);
503 * Can't use css_tryget_online() here. A task which has
504 * PF_EXITING set may stay associated with an offline css.
505 * If such task calls this function, css_tryget_online()
508 if (likely(css_tryget(css)))
517 * task_css_is_root - test whether a task belongs to the root css
518 * @task: the target task
519 * @subsys_id: the target subsystem ID
521 * Test whether @task belongs to the root css on the specified subsystem.
522 * May be invoked in any context.
524 static inline bool task_css_is_root(struct task_struct *task, int subsys_id)
526 return task_css_check(task, subsys_id, true) ==
527 init_css_set.subsys[subsys_id];
530 static inline struct cgroup *task_cgroup(struct task_struct *task,
533 return task_css(task, subsys_id)->cgroup;
536 static inline struct cgroup *task_dfl_cgroup(struct task_struct *task)
538 return task_css_set(task)->dfl_cgrp;
541 static inline struct cgroup *cgroup_parent(struct cgroup *cgrp)
543 struct cgroup_subsys_state *parent_css = cgrp->self.parent;
546 return container_of(parent_css, struct cgroup, self);
551 * cgroup_is_descendant - test ancestry
552 * @cgrp: the cgroup to be tested
553 * @ancestor: possible ancestor of @cgrp
555 * Test whether @cgrp is a descendant of @ancestor. It also returns %true
556 * if @cgrp == @ancestor. This function is safe to call as long as @cgrp
557 * and @ancestor are accessible.
559 static inline bool cgroup_is_descendant(struct cgroup *cgrp,
560 struct cgroup *ancestor)
562 if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)
564 return cgrp->ancestor_ids[ancestor->level] == ancestor->id;
568 * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry
569 * @task: the task to be tested
570 * @ancestor: possible ancestor of @task's cgroup
572 * Tests whether @task's default cgroup hierarchy is a descendant of @ancestor.
573 * It follows all the same rules as cgroup_is_descendant, and only applies
574 * to the default hierarchy.
576 static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
577 struct cgroup *ancestor)
579 struct css_set *cset = task_css_set(task);
581 return cgroup_is_descendant(cset->dfl_cgrp, ancestor);
584 /* no synchronization, the result can only be used as a hint */
585 static inline bool cgroup_is_populated(struct cgroup *cgrp)
587 return cgrp->nr_populated_csets + cgrp->nr_populated_domain_children +
588 cgrp->nr_populated_threaded_children;
591 /* returns ino associated with a cgroup */
592 static inline ino_t cgroup_ino(struct cgroup *cgrp)
594 return cgrp->kn->id.ino;
597 /* cft/css accessors for cftype->write() operation */
598 static inline struct cftype *of_cft(struct kernfs_open_file *of)
603 struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
605 /* cft/css accessors for cftype->seq_*() operations */
606 static inline struct cftype *seq_cft(struct seq_file *seq)
608 return of_cft(seq->private);
611 static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
613 return of_css(seq->private);
617 * Name / path handling functions. All are thin wrappers around the kernfs
618 * counterparts and can be called under any context.
621 static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
623 return kernfs_name(cgrp->kn, buf, buflen);
626 static inline int cgroup_path(struct cgroup *cgrp, char *buf, size_t buflen)
628 return kernfs_path(cgrp->kn, buf, buflen);
631 static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
633 pr_cont_kernfs_name(cgrp->kn);
636 static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
638 pr_cont_kernfs_path(cgrp->kn);
641 static inline void cgroup_init_kthreadd(void)
644 * kthreadd is inherited by all kthreads, keep it in the root so
645 * that the new kthreads are guaranteed to stay in the root until
646 * initialization is finished.
648 current->no_cgroup_migration = 1;
651 static inline void cgroup_kthread_ready(void)
654 * This kthread finished initialization. The creator should have
655 * set PF_NO_SETAFFINITY if this kthread should stay in the root.
657 current->no_cgroup_migration = 0;
660 static inline union kernfs_node_id *cgroup_get_kernfs_id(struct cgroup *cgrp)
662 return &cgrp->kn->id;
665 void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
666 char *buf, size_t buflen);
667 #else /* !CONFIG_CGROUPS */
669 struct cgroup_subsys_state;
672 static inline void css_put(struct cgroup_subsys_state *css) {}
673 static inline int cgroup_attach_task_all(struct task_struct *from,
674 struct task_struct *t) { return 0; }
675 static inline int cgroupstats_build(struct cgroupstats *stats,
676 struct dentry *dentry) { return -EINVAL; }
678 static inline void cgroup_fork(struct task_struct *p) {}
679 static inline int cgroup_can_fork(struct task_struct *p) { return 0; }
680 static inline void cgroup_cancel_fork(struct task_struct *p) {}
681 static inline void cgroup_post_fork(struct task_struct *p) {}
682 static inline void cgroup_exit(struct task_struct *p) {}
683 static inline void cgroup_release(struct task_struct *p) {}
684 static inline void cgroup_free(struct task_struct *p) {}
686 static inline int cgroup_init_early(void) { return 0; }
687 static inline int cgroup_init(void) { return 0; }
688 static inline void cgroup_init_kthreadd(void) {}
689 static inline void cgroup_kthread_ready(void) {}
690 static inline union kernfs_node_id *cgroup_get_kernfs_id(struct cgroup *cgrp)
695 static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
696 struct cgroup *ancestor)
701 static inline void cgroup_path_from_kernfs_id(const union kernfs_node_id *id,
702 char *buf, size_t buflen) {}
703 #endif /* !CONFIG_CGROUPS */
706 * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
707 * definition in cgroup-defs.h.
709 #ifdef CONFIG_SOCK_CGROUP_DATA
711 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
712 extern spinlock_t cgroup_sk_update_lock;
715 void cgroup_sk_alloc_disable(void);
716 void cgroup_sk_alloc(struct sock_cgroup_data *skcd);
717 void cgroup_sk_clone(struct sock_cgroup_data *skcd);
718 void cgroup_sk_free(struct sock_cgroup_data *skcd);
720 static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd)
722 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
726 * @skcd->val is 64bit but the following is safe on 32bit too as we
727 * just need the lower ulong to be written and read atomically.
729 v = READ_ONCE(skcd->val);
732 return &cgrp_dfl_root.cgrp;
734 return (struct cgroup *)(unsigned long)v ?: &cgrp_dfl_root.cgrp;
736 return (struct cgroup *)(unsigned long)skcd->val;
740 #else /* CONFIG_CGROUP_DATA */
742 static inline void cgroup_sk_alloc(struct sock_cgroup_data *skcd) {}
743 static inline void cgroup_sk_clone(struct sock_cgroup_data *skcd) {}
744 static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {}
746 #endif /* CONFIG_CGROUP_DATA */
748 struct cgroup_namespace {
751 struct user_namespace *user_ns;
752 struct ucounts *ucounts;
753 struct css_set *root_cset;
756 extern struct cgroup_namespace init_cgroup_ns;
758 #ifdef CONFIG_CGROUPS
760 void free_cgroup_ns(struct cgroup_namespace *ns);
762 struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
763 struct user_namespace *user_ns,
764 struct cgroup_namespace *old_ns);
766 int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
767 struct cgroup_namespace *ns);
769 #else /* !CONFIG_CGROUPS */
771 static inline void free_cgroup_ns(struct cgroup_namespace *ns) { }
772 static inline struct cgroup_namespace *
773 copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns,
774 struct cgroup_namespace *old_ns)
779 #endif /* !CONFIG_CGROUPS */
781 static inline void get_cgroup_ns(struct cgroup_namespace *ns)
784 refcount_inc(&ns->count);
787 static inline void put_cgroup_ns(struct cgroup_namespace *ns)
789 if (ns && refcount_dec_and_test(&ns->count))
793 #endif /* _LINUX_CGROUP_H */