source: src/linux/universal/linux-4.9/include/linux/cgroup.h @ 31885

Last change on this file since 31885 was 31885, checked in by brainslayer, 3 months ago

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1#ifndef _LINUX_CGROUP_H
2#define _LINUX_CGROUP_H
3/*
4 *  cgroup interface
5 *
6 *  Copyright (C) 2003 BULL SA
7 *  Copyright (C) 2004-2006 Silicon Graphics, Inc.
8 *
9 */
10
11#include <linux/sched.h>
12#include <linux/cpumask.h>
13#include <linux/nodemask.h>
14#include <linux/rculist.h>
15#include <linux/cgroupstats.h>
16#include <linux/fs.h>
17#include <linux/seq_file.h>
18#include <linux/kernfs.h>
19#include <linux/jump_label.h>
20#include <linux/nsproxy.h>
21#include <linux/types.h>
22#include <linux/ns_common.h>
23#include <linux/nsproxy.h>
24#include <linux/user_namespace.h>
25
26#include <linux/cgroup-defs.h>
27
28#ifdef CONFIG_CGROUPS
29
30/*
31 * All weight knobs on the default hierarhcy should use the following min,
32 * default and max values.  The default value is the logarithmic center of
33 * MIN and MAX and allows 100x to be expressed in both directions.
34 */
35#define CGROUP_WEIGHT_MIN               1
36#define CGROUP_WEIGHT_DFL               100
37#define CGROUP_WEIGHT_MAX               10000
38
39/* a css_task_iter should be treated as an opaque object */
40struct css_task_iter {
41        struct cgroup_subsys            *ss;
42
43        struct list_head                *cset_pos;
44        struct list_head                *cset_head;
45
46        struct list_head                *task_pos;
47        struct list_head                *tasks_head;
48        struct list_head                *mg_tasks_head;
49
50        struct css_set                  *cur_cset;
51        struct task_struct              *cur_task;
52        struct list_head                iters_node;     /* css_set->task_iters */
53};
54
55extern struct cgroup_root cgrp_dfl_root;
56extern struct css_set init_css_set;
57
58#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
59#include <linux/cgroup_subsys.h>
60#undef SUBSYS
61
62#define SUBSYS(_x)                                                              \
63        extern struct static_key_true _x ## _cgrp_subsys_enabled_key;           \
64        extern struct static_key_true _x ## _cgrp_subsys_on_dfl_key;
65#include <linux/cgroup_subsys.h>
66#undef SUBSYS
67
68/**
69 * cgroup_subsys_enabled - fast test on whether a subsys is enabled
70 * @ss: subsystem in question
71 */
72#define cgroup_subsys_enabled(ss)                                               \
73        static_branch_likely(&ss ## _enabled_key)
74
75/**
76 * cgroup_subsys_on_dfl - fast test on whether a subsys is on default hierarchy
77 * @ss: subsystem in question
78 */
79#define cgroup_subsys_on_dfl(ss)                                                \
80        static_branch_likely(&ss ## _on_dfl_key)
81
82bool css_has_online_children(struct cgroup_subsys_state *css);
83struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
84struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup,
85                                             struct cgroup_subsys *ss);
86struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
87                                                       struct cgroup_subsys *ss);
88
89struct cgroup *cgroup_get_from_path(const char *path);
90struct cgroup *cgroup_get_from_fd(int fd);
91
92int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
93int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
94
95int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
96int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
97int cgroup_rm_cftypes(struct cftype *cfts);
98void cgroup_file_notify(struct cgroup_file *cfile);
99
100int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
101int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry);
102int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
103                     struct pid *pid, struct task_struct *tsk);
104
105void cgroup_fork(struct task_struct *p);
106extern int cgroup_can_fork(struct task_struct *p);
107extern void cgroup_cancel_fork(struct task_struct *p);
108extern void cgroup_post_fork(struct task_struct *p);
109void cgroup_exit(struct task_struct *p);
110void cgroup_free(struct task_struct *p);
111
112int cgroup_init_early(void);
113int cgroup_init(void);
114
115/*
116 * Iteration helpers and macros.
117 */
118
119struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
120                                           struct cgroup_subsys_state *parent);
121struct cgroup_subsys_state *css_next_descendant_pre(struct cgroup_subsys_state *pos,
122                                                    struct cgroup_subsys_state *css);
123struct cgroup_subsys_state *css_rightmost_descendant(struct cgroup_subsys_state *pos);
124struct cgroup_subsys_state *css_next_descendant_post(struct cgroup_subsys_state *pos,
125                                                     struct cgroup_subsys_state *css);
126
127struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
128                                         struct cgroup_subsys_state **dst_cssp);
129struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
130                                        struct cgroup_subsys_state **dst_cssp);
131
132void css_task_iter_start(struct cgroup_subsys_state *css,
133                         struct css_task_iter *it);
134struct task_struct *css_task_iter_next(struct css_task_iter *it);
135void css_task_iter_end(struct css_task_iter *it);
136
137/**
138 * css_for_each_child - iterate through children of a css
139 * @pos: the css * to use as the loop cursor
140 * @parent: css whose children to walk
141 *
142 * Walk @parent's children.  Must be called under rcu_read_lock().
143 *
144 * If a subsystem synchronizes ->css_online() and the start of iteration, a
145 * css which finished ->css_online() is guaranteed to be visible in the
146 * future iterations and will stay visible until the last reference is put.
147 * A css which hasn't finished ->css_online() or already finished
148 * ->css_offline() may show up during traversal.  It's each subsystem's
149 * responsibility to synchronize against on/offlining.
150 *
151 * It is allowed to temporarily drop RCU read lock during iteration.  The
152 * caller is responsible for ensuring that @pos remains accessible until
153 * the start of the next iteration by, for example, bumping the css refcnt.
154 */
155#define css_for_each_child(pos, parent)                                 \
156        for ((pos) = css_next_child(NULL, (parent)); (pos);             \
157             (pos) = css_next_child((pos), (parent)))
158
159/**
160 * css_for_each_descendant_pre - pre-order walk of a css's descendants
161 * @pos: the css * to use as the loop cursor
162 * @root: css whose descendants to walk
163 *
164 * Walk @root's descendants.  @root is included in the iteration and the
165 * first node to be visited.  Must be called under rcu_read_lock().
166 *
167 * If a subsystem synchronizes ->css_online() and the start of iteration, a
168 * css which finished ->css_online() is guaranteed to be visible in the
169 * future iterations and will stay visible until the last reference is put.
170 * A css which hasn't finished ->css_online() or already finished
171 * ->css_offline() may show up during traversal.  It's each subsystem's
172 * responsibility to synchronize against on/offlining.
173 *
174 * For example, the following guarantees that a descendant can't escape
175 * state updates of its ancestors.
176 *
177 * my_online(@css)
178 * {
179 *      Lock @css's parent and @css;
180 *      Inherit state from the parent;
181 *      Unlock both.
182 * }
183 *
184 * my_update_state(@css)
185 * {
186 *      css_for_each_descendant_pre(@pos, @css) {
187 *              Lock @pos;
188 *              if (@pos == @css)
189 *                      Update @css's state;
190 *              else
191 *                      Verify @pos is alive and inherit state from its parent;
192 *              Unlock @pos;
193 *      }
194 * }
195 *
196 * As long as the inheriting step, including checking the parent state, is
197 * enclosed inside @pos locking, double-locking the parent isn't necessary
198 * while inheriting.  The state update to the parent is guaranteed to be
199 * visible by walking order and, as long as inheriting operations to the
200 * same @pos are atomic to each other, multiple updates racing each other
201 * still result in the correct state.  It's guaranateed that at least one
202 * inheritance happens for any css after the latest update to its parent.
203 *
204 * If checking parent's state requires locking the parent, each inheriting
205 * iteration should lock and unlock both @pos->parent and @pos.
206 *
207 * Alternatively, a subsystem may choose to use a single global lock to
208 * synchronize ->css_online() and ->css_offline() against tree-walking
209 * operations.
210 *
211 * It is allowed to temporarily drop RCU read lock during iteration.  The
212 * caller is responsible for ensuring that @pos remains accessible until
213 * the start of the next iteration by, for example, bumping the css refcnt.
214 */
215#define css_for_each_descendant_pre(pos, css)                           \
216        for ((pos) = css_next_descendant_pre(NULL, (css)); (pos);       \
217             (pos) = css_next_descendant_pre((pos), (css)))
218
219/**
220 * css_for_each_descendant_post - post-order walk of a css's descendants
221 * @pos: the css * to use as the loop cursor
222 * @css: css whose descendants to walk
223 *
224 * Similar to css_for_each_descendant_pre() but performs post-order
225 * traversal instead.  @root is included in the iteration and the last
226 * node to be visited.
227 *
228 * If a subsystem synchronizes ->css_online() and the start of iteration, a
229 * css which finished ->css_online() is guaranteed to be visible in the
230 * future iterations and will stay visible until the last reference is put.
231 * A css which hasn't finished ->css_online() or already finished
232 * ->css_offline() may show up during traversal.  It's each subsystem's
233 * responsibility to synchronize against on/offlining.
234 *
235 * Note that the walk visibility guarantee example described in pre-order
236 * walk doesn't apply the same to post-order walks.
237 */
238#define css_for_each_descendant_post(pos, css)                          \
239        for ((pos) = css_next_descendant_post(NULL, (css)); (pos);      \
240             (pos) = css_next_descendant_post((pos), (css)))
241
242/**
243 * cgroup_taskset_for_each - iterate cgroup_taskset
244 * @task: the loop cursor
245 * @dst_css: the destination css
246 * @tset: taskset to iterate
247 *
248 * @tset may contain multiple tasks and they may belong to multiple
249 * processes.
250 *
251 * On the v2 hierarchy, there may be tasks from multiple processes and they
252 * may not share the source or destination csses.
253 *
254 * On traditional hierarchies, when there are multiple tasks in @tset, if a
255 * task of a process is in @tset, all tasks of the process are in @tset.
256 * Also, all are guaranteed to share the same source and destination csses.
257 *
258 * Iteration is not in any specific order.
259 */
260#define cgroup_taskset_for_each(task, dst_css, tset)                    \
261        for ((task) = cgroup_taskset_first((tset), &(dst_css));         \
262             (task);                                                    \
263             (task) = cgroup_taskset_next((tset), &(dst_css)))
264
265/**
266 * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset
267 * @leader: the loop cursor
268 * @dst_css: the destination css
269 * @tset: takset to iterate
270 *
271 * Iterate threadgroup leaders of @tset.  For single-task migrations, @tset
272 * may not contain any.
273 */
274#define cgroup_taskset_for_each_leader(leader, dst_css, tset)           \
275        for ((leader) = cgroup_taskset_first((tset), &(dst_css));       \
276             (leader);                                                  \
277             (leader) = cgroup_taskset_next((tset), &(dst_css)))        \
278                if ((leader) != (leader)->group_leader)                 \
279                        ;                                               \
280                else
281
282/*
283 * Inline functions.
284 */
285
286/**
287 * css_get - obtain a reference on the specified css
288 * @css: target css
289 *
290 * The caller must already have a reference.
291 */
292static inline void css_get(struct cgroup_subsys_state *css)
293{
294        if (!(css->flags & CSS_NO_REF))
295                percpu_ref_get(&css->refcnt);
296}
297
298/**
299 * css_get_many - obtain references on the specified css
300 * @css: target css
301 * @n: number of references to get
302 *
303 * The caller must already have a reference.
304 */
305static inline void css_get_many(struct cgroup_subsys_state *css, unsigned int n)
306{
307        if (!(css->flags & CSS_NO_REF))
308                percpu_ref_get_many(&css->refcnt, n);
309}
310
311/**
312 * css_tryget - try to obtain a reference on the specified css
313 * @css: target css
314 *
315 * Obtain a reference on @css unless it already has reached zero and is
316 * being released.  This function doesn't care whether @css is on or
317 * offline.  The caller naturally needs to ensure that @css is accessible
318 * but doesn't have to be holding a reference on it - IOW, RCU protected
319 * access is good enough for this function.  Returns %true if a reference
320 * count was successfully obtained; %false otherwise.
321 */
322static inline bool css_tryget(struct cgroup_subsys_state *css)
323{
324        if (!(css->flags & CSS_NO_REF))
325                return percpu_ref_tryget(&css->refcnt);
326        return true;
327}
328
329/**
330 * css_tryget_online - try to obtain a reference on the specified css if online
331 * @css: target css
332 *
333 * Obtain a reference on @css if it's online.  The caller naturally needs
334 * to ensure that @css is accessible but doesn't have to be holding a
335 * reference on it - IOW, RCU protected access is good enough for this
336 * function.  Returns %true if a reference count was successfully obtained;
337 * %false otherwise.
338 */
339static inline bool css_tryget_online(struct cgroup_subsys_state *css)
340{
341        if (!(css->flags & CSS_NO_REF))
342                return percpu_ref_tryget_live(&css->refcnt);
343        return true;
344}
345
346/**
347 * css_put - put a css reference
348 * @css: target css
349 *
350 * Put a reference obtained via css_get() and css_tryget_online().
351 */
352static inline void css_put(struct cgroup_subsys_state *css)
353{
354        if (!(css->flags & CSS_NO_REF))
355                percpu_ref_put(&css->refcnt);
356}
357
358/**
359 * css_put_many - put css references
360 * @css: target css
361 * @n: number of references to put
362 *
363 * Put references obtained via css_get() and css_tryget_online().
364 */
365static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n)
366{
367        if (!(css->flags & CSS_NO_REF))
368                percpu_ref_put_many(&css->refcnt, n);
369}
370
371static inline void cgroup_put(struct cgroup *cgrp)
372{
373        css_put(&cgrp->self);
374}
375
376/**
377 * task_css_set_check - obtain a task's css_set with extra access conditions
378 * @task: the task to obtain css_set for
379 * @__c: extra condition expression to be passed to rcu_dereference_check()
380 *
381 * A task's css_set is RCU protected, initialized and exited while holding
382 * task_lock(), and can only be modified while holding both cgroup_mutex
383 * and task_lock() while the task is alive.  This macro verifies that the
384 * caller is inside proper critical section and returns @task's css_set.
385 *
386 * The caller can also specify additional allowed conditions via @__c, such
387 * as locks used during the cgroup_subsys::attach() methods.
388 */
389#ifdef CONFIG_PROVE_RCU
390extern struct mutex cgroup_mutex;
391extern spinlock_t css_set_lock;
392#define task_css_set_check(task, __c)                                   \
393        rcu_dereference_check((task)->cgroups,                          \
394                lockdep_is_held(&cgroup_mutex) ||                       \
395                lockdep_is_held(&css_set_lock) ||                       \
396                ((task)->flags & PF_EXITING) || (__c))
397#else
398#define task_css_set_check(task, __c)                                   \
399        rcu_dereference((task)->cgroups)
400#endif
401
402/**
403 * task_css_check - obtain css for (task, subsys) w/ extra access conds
404 * @task: the target task
405 * @subsys_id: the target subsystem ID
406 * @__c: extra condition expression to be passed to rcu_dereference_check()
407 *
408 * Return the cgroup_subsys_state for the (@task, @subsys_id) pair.  The
409 * synchronization rules are the same as task_css_set_check().
410 */
411#define task_css_check(task, subsys_id, __c)                            \
412        task_css_set_check((task), (__c))->subsys[(subsys_id)]
413
414/**
415 * task_css_set - obtain a task's css_set
416 * @task: the task to obtain css_set for
417 *
418 * See task_css_set_check().
419 */
420static inline struct css_set *task_css_set(struct task_struct *task)
421{
422        return task_css_set_check(task, false);
423}
424
425/**
426 * task_css - obtain css for (task, subsys)
427 * @task: the target task
428 * @subsys_id: the target subsystem ID
429 *
430 * See task_css_check().
431 */
432static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
433                                                   int subsys_id)
434{
435        return task_css_check(task, subsys_id, false);
436}
437
438/**
439 * task_get_css - find and get the css for (task, subsys)
440 * @task: the target task
441 * @subsys_id: the target subsystem ID
442 *
443 * Find the css for the (@task, @subsys_id) combination, increment a
444 * reference on and return it.  This function is guaranteed to return a
445 * valid css.
446 */
447static inline struct cgroup_subsys_state *
448task_get_css(struct task_struct *task, int subsys_id)
449{
450        struct cgroup_subsys_state *css;
451
452        rcu_read_lock();
453        while (true) {
454                css = task_css(task, subsys_id);
455                if (likely(css_tryget_online(css)))
456                        break;
457                cpu_relax();
458        }
459        rcu_read_unlock();
460        return css;
461}
462
463/**
464 * task_css_is_root - test whether a task belongs to the root css
465 * @task: the target task
466 * @subsys_id: the target subsystem ID
467 *
468 * Test whether @task belongs to the root css on the specified subsystem.
469 * May be invoked in any context.
470 */
471static inline bool task_css_is_root(struct task_struct *task, int subsys_id)
472{
473        return task_css_check(task, subsys_id, true) ==
474                init_css_set.subsys[subsys_id];
475}
476
477static inline struct cgroup *task_cgroup(struct task_struct *task,
478                                         int subsys_id)
479{
480        return task_css(task, subsys_id)->cgroup;
481}
482
483/**
484 * cgroup_is_descendant - test ancestry
485 * @cgrp: the cgroup to be tested
486 * @ancestor: possible ancestor of @cgrp
487 *
488 * Test whether @cgrp is a descendant of @ancestor.  It also returns %true
489 * if @cgrp == @ancestor.  This function is safe to call as long as @cgrp
490 * and @ancestor are accessible.
491 */
492static inline bool cgroup_is_descendant(struct cgroup *cgrp,
493                                        struct cgroup *ancestor)
494{
495        if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)
496                return false;
497        return cgrp->ancestor_ids[ancestor->level] == ancestor->id;
498}
499
500/**
501 * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry
502 * @task: the task to be tested
503 * @ancestor: possible ancestor of @task's cgroup
504 *
505 * Tests whether @task's default cgroup hierarchy is a descendant of @ancestor.
506 * It follows all the same rules as cgroup_is_descendant, and only applies
507 * to the default hierarchy.
508 */
509static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
510                                               struct cgroup *ancestor)
511{
512        struct css_set *cset = task_css_set(task);
513
514        return cgroup_is_descendant(cset->dfl_cgrp, ancestor);
515}
516
517/* no synchronization, the result can only be used as a hint */
518static inline bool cgroup_is_populated(struct cgroup *cgrp)
519{
520        return cgrp->populated_cnt;
521}
522
523/* returns ino associated with a cgroup */
524static inline ino_t cgroup_ino(struct cgroup *cgrp)
525{
526        return cgrp->kn->ino;
527}
528
529/* cft/css accessors for cftype->write() operation */
530static inline struct cftype *of_cft(struct kernfs_open_file *of)
531{
532        return of->kn->priv;
533}
534
535struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
536
537/* cft/css accessors for cftype->seq_*() operations */
538static inline struct cftype *seq_cft(struct seq_file *seq)
539{
540        return of_cft(seq->private);
541}
542
543static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
544{
545        return of_css(seq->private);
546}
547
548/*
549 * Name / path handling functions.  All are thin wrappers around the kernfs
550 * counterparts and can be called under any context.
551 */
552
553static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
554{
555        return kernfs_name(cgrp->kn, buf, buflen);
556}
557
558static inline int cgroup_path(struct cgroup *cgrp, char *buf, size_t buflen)
559{
560        return kernfs_path(cgrp->kn, buf, buflen);
561}
562
563static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
564{
565        pr_cont_kernfs_name(cgrp->kn);
566}
567
568static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
569{
570        pr_cont_kernfs_path(cgrp->kn);
571}
572
573static inline void cgroup_init_kthreadd(void)
574{
575        /*
576         * kthreadd is inherited by all kthreads, keep it in the root so
577         * that the new kthreads are guaranteed to stay in the root until
578         * initialization is finished.
579         */
580        current->no_cgroup_migration = 1;
581}
582
583static inline void cgroup_kthread_ready(void)
584{
585        /*
586         * This kthread finished initialization.  The creator should have
587         * set PF_NO_SETAFFINITY if this kthread should stay in the root.
588         */
589        current->no_cgroup_migration = 0;
590}
591
592#else /* !CONFIG_CGROUPS */
593
594struct cgroup_subsys_state;
595struct cgroup;
596
597static inline void css_put(struct cgroup_subsys_state *css) {}
598static inline int cgroup_attach_task_all(struct task_struct *from,
599                                         struct task_struct *t) { return 0; }
600static inline int cgroupstats_build(struct cgroupstats *stats,
601                                    struct dentry *dentry) { return -EINVAL; }
602
603static inline void cgroup_fork(struct task_struct *p) {}
604static inline int cgroup_can_fork(struct task_struct *p) { return 0; }
605static inline void cgroup_cancel_fork(struct task_struct *p) {}
606static inline void cgroup_post_fork(struct task_struct *p) {}
607static inline void cgroup_exit(struct task_struct *p) {}
608static inline void cgroup_free(struct task_struct *p) {}
609
610static inline int cgroup_init_early(void) { return 0; }
611static inline int cgroup_init(void) { return 0; }
612static inline void cgroup_init_kthreadd(void) {}
613static inline void cgroup_kthread_ready(void) {}
614
615static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
616                                               struct cgroup *ancestor)
617{
618        return true;
619}
620#endif /* !CONFIG_CGROUPS */
621
622/*
623 * sock->sk_cgrp_data handling.  For more info, see sock_cgroup_data
624 * definition in cgroup-defs.h.
625 */
626#ifdef CONFIG_SOCK_CGROUP_DATA
627
628#if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
629extern spinlock_t cgroup_sk_update_lock;
630#endif
631
632void cgroup_sk_alloc_disable(void);
633void cgroup_sk_alloc(struct sock_cgroup_data *skcd);
634void cgroup_sk_free(struct sock_cgroup_data *skcd);
635
636static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd)
637{
638#if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
639        unsigned long v;
640
641        /*
642         * @skcd->val is 64bit but the following is safe on 32bit too as we
643         * just need the lower ulong to be written and read atomically.
644         */
645        v = READ_ONCE(skcd->val);
646
647        if (v & 1)
648                return &cgrp_dfl_root.cgrp;
649
650        return (struct cgroup *)(unsigned long)v ?: &cgrp_dfl_root.cgrp;
651#else
652        return (struct cgroup *)(unsigned long)skcd->val;
653#endif
654}
655
656#else   /* CONFIG_CGROUP_DATA */
657
658static inline void cgroup_sk_alloc(struct sock_cgroup_data *skcd) {}
659static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {}
660
661#endif  /* CONFIG_CGROUP_DATA */
662
663struct cgroup_namespace {
664        atomic_t                count;
665        struct ns_common        ns;
666        struct user_namespace   *user_ns;
667        struct ucounts          *ucounts;
668        struct css_set          *root_cset;
669};
670
671extern struct cgroup_namespace init_cgroup_ns;
672
673#ifdef CONFIG_CGROUPS
674
675void free_cgroup_ns(struct cgroup_namespace *ns);
676
677struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
678                                        struct user_namespace *user_ns,
679                                        struct cgroup_namespace *old_ns);
680
681int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
682                   struct cgroup_namespace *ns);
683
684#else /* !CONFIG_CGROUPS */
685
686static inline void free_cgroup_ns(struct cgroup_namespace *ns) { }
687static inline struct cgroup_namespace *
688copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns,
689               struct cgroup_namespace *old_ns)
690{
691        return old_ns;
692}
693
694#endif /* !CONFIG_CGROUPS */
695
696static inline void get_cgroup_ns(struct cgroup_namespace *ns)
697{
698        if (ns)
699                atomic_inc(&ns->count);
700}
701
702static inline void put_cgroup_ns(struct cgroup_namespace *ns)
703{
704        if (ns && atomic_dec_and_test(&ns->count))
705                free_cgroup_ns(ns);
706}
707
708#endif /* _LINUX_CGROUP_H */
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