1 #ifndef _LINUX_CGROUP_H
2 #define _LINUX_CGROUP_H
6 * Copyright (C) 2003 BULL SA
7 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
11 #include <linux/sched.h>
12 #include <linux/cpumask.h>
13 #include <linux/nodemask.h>
14 #include <linux/rcupdate.h>
15 #include <linux/rculist.h>
16 #include <linux/cgroupstats.h>
17 #include <linux/rwsem.h>
18 #include <linux/idr.h>
19 #include <linux/workqueue.h>
21 #include <linux/percpu-refcount.h>
22 #include <linux/seq_file.h>
23 #include <linux/kernfs.h>
32 extern int cgroup_init_early(void);
33 extern int cgroup_init(void);
34 extern void cgroup_fork(struct task_struct *p);
35 extern void cgroup_post_fork(struct task_struct *p);
36 extern void cgroup_exit(struct task_struct *p, int run_callbacks);
37 extern int cgroupstats_build(struct cgroupstats *stats,
38 struct dentry *dentry);
40 extern int proc_cgroup_show(struct seq_file *, void *);
42 /* define the enumeration of all cgroup subsystems */
43 #define SUBSYS(_x) _x ## _cgrp_id,
44 enum cgroup_subsys_id {
45 #include <linux/cgroup_subsys.h>
50 /* Per-subsystem/per-cgroup state maintained by the system. */
51 struct cgroup_subsys_state {
52 /* the cgroup that this css is attached to */
53 struct cgroup *cgroup;
55 /* the cgroup subsystem that this css is attached to */
56 struct cgroup_subsys *ss;
58 /* reference count - access via css_[try]get() and css_put() */
59 struct percpu_ref refcnt;
62 struct cgroup_subsys_state *parent;
66 /* percpu_ref killing and RCU release */
67 struct rcu_head rcu_head;
68 struct work_struct destroy_work;
71 /* bits in struct cgroup_subsys_state flags field */
73 CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */
74 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
78 * css_get - obtain a reference on the specified css
81 * The caller must already have a reference.
83 static inline void css_get(struct cgroup_subsys_state *css)
85 /* We don't need to reference count the root state */
86 if (!(css->flags & CSS_ROOT))
87 percpu_ref_get(&css->refcnt);
91 * css_tryget - try to obtain a reference on the specified css
94 * Obtain a reference on @css if it's alive. The caller naturally needs to
95 * ensure that @css is accessible but doesn't have to be holding a
96 * reference on it - IOW, RCU protected access is good enough for this
97 * function. Returns %true if a reference count was successfully obtained;
100 static inline bool css_tryget(struct cgroup_subsys_state *css)
102 if (css->flags & CSS_ROOT)
104 return percpu_ref_tryget(&css->refcnt);
108 * css_put - put a css reference
111 * Put a reference obtained via css_get() and css_tryget().
113 static inline void css_put(struct cgroup_subsys_state *css)
115 if (!(css->flags & CSS_ROOT))
116 percpu_ref_put(&css->refcnt);
119 /* bits in struct cgroup flags field */
121 /* Control Group is dead */
124 * Control Group has previously had a child cgroup or a task,
125 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
128 /* Control Group requires release notifications to userspace */
129 CGRP_NOTIFY_ON_RELEASE,
131 * Clone the parent's configuration when creating a new child
132 * cpuset cgroup. For historical reasons, this option can be
133 * specified at mount time and thus is implemented here.
135 CGRP_CPUSET_CLONE_CHILDREN,
136 /* see the comment above CGRP_ROOT_SANE_BEHAVIOR for details */
141 unsigned long flags; /* "unsigned long" so bitops work */
144 * idr allocated in-hierarchy ID.
146 * The ID of the root cgroup is always 0, and a new cgroup
147 * will be assigned with a smallest available ID.
149 * Allocating/Removing ID must be protected by cgroup_mutex.
153 /* the number of attached css's */
159 * We link our 'sibling' struct into our parent's 'children'.
160 * Our children link their 'sibling' into our 'children'.
162 struct list_head sibling; /* my parent's children */
163 struct list_head children; /* my children */
165 struct cgroup *parent; /* my parent */
166 struct kernfs_node *kn; /* cgroup kernfs entry */
169 * Monotonically increasing unique serial number which defines a
170 * uniform order among all cgroups. It's guaranteed that all
171 * ->children lists are in the ascending order of ->serial_nr.
172 * It's used to allow interrupting and resuming iterations.
176 /* Private pointers for each registered subsystem */
177 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
179 struct cgroupfs_root *root;
182 * List of cgrp_cset_links pointing at css_sets with tasks in this
183 * cgroup. Protected by css_set_lock.
185 struct list_head cset_links;
188 * Linked list running through all cgroups that can
189 * potentially be reaped by the release agent. Protected by
192 struct list_head release_list;
195 * list of pidlists, up to two for each namespace (one for procs, one
196 * for tasks); created on demand.
198 struct list_head pidlists;
199 struct mutex pidlist_mutex;
201 /* dummy css with NULL ->ss, points back to this cgroup */
202 struct cgroup_subsys_state dummy_css;
204 /* For css percpu_ref killing and RCU-protected deletion */
205 struct rcu_head rcu_head;
206 struct work_struct destroy_work;
209 #define MAX_CGROUP_ROOT_NAMELEN 64
211 /* cgroupfs_root->flags */
214 * Unfortunately, cgroup core and various controllers are riddled
215 * with idiosyncrasies and pointless options. The following flag,
216 * when set, will force sane behavior - some options are forced on,
217 * others are disallowed, and some controllers will change their
218 * hierarchical or other behaviors.
220 * The set of behaviors affected by this flag are still being
221 * determined and developed and the mount option for this flag is
222 * prefixed with __DEVEL__. The prefix will be dropped once we
223 * reach the point where all behaviors are compatible with the
224 * planned unified hierarchy, which will automatically turn on this
227 * The followings are the behaviors currently affected this flag.
229 * - Mount options "noprefix", "xattr", "clone_children",
230 * "release_agent" and "name" are disallowed.
232 * - When mounting an existing superblock, mount options should
235 * - Remount is disallowed.
237 * - rename(2) is disallowed.
239 * - "tasks" is removed. Everything should be at process
240 * granularity. Use "cgroup.procs" instead.
242 * - "cgroup.procs" is not sorted. pids will be unique unless they
243 * got recycled inbetween reads.
245 * - "release_agent" and "notify_on_release" are removed.
246 * Replacement notification mechanism will be implemented.
248 * - "cgroup.clone_children" is removed.
250 * - cpuset: tasks will be kept in empty cpusets when hotplug happens
251 * and take masks of ancestors with non-empty cpus/mems, instead of
252 * being moved to an ancestor.
254 * - cpuset: a task can be moved into an empty cpuset, and again it
255 * takes masks of ancestors.
257 * - memcg: use_hierarchy is on by default and the cgroup file for
258 * the flag is not created.
260 * - blkcg: blk-throttle becomes properly hierarchical.
262 CGRP_ROOT_SANE_BEHAVIOR = (1 << 0),
264 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
265 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
267 /* mount options live below bit 16 */
268 CGRP_ROOT_OPTION_MASK = (1 << 16) - 1,
272 * A cgroupfs_root represents the root of a cgroup hierarchy, and may be
273 * associated with a kernfs_root to form an active hierarchy. This is
274 * internal to cgroup core. Don't access directly from controllers.
276 struct cgroupfs_root {
277 struct kernfs_root *kf_root;
279 /* The bitmask of subsystems attached to this hierarchy */
280 unsigned long subsys_mask;
282 /* Unique id for this hierarchy. */
285 /* The root cgroup. Root is destroyed on its release. */
286 struct cgroup top_cgroup;
288 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
291 /* A list running through the active hierarchies */
292 struct list_head root_list;
294 /* Hierarchy-specific flags */
297 /* IDs for cgroups in this hierarchy */
298 struct idr cgroup_idr;
300 /* The path to use for release notifications. */
301 char release_agent_path[PATH_MAX];
303 /* The name for this hierarchy - may be empty */
304 char name[MAX_CGROUP_ROOT_NAMELEN];
308 * A css_set is a structure holding pointers to a set of
309 * cgroup_subsys_state objects. This saves space in the task struct
310 * object and speeds up fork()/exit(), since a single inc/dec and a
311 * list_add()/del() can bump the reference count on the entire cgroup
317 /* Reference count */
321 * List running through all cgroup groups in the same hash
322 * slot. Protected by css_set_lock
324 struct hlist_node hlist;
327 * List running through all tasks using this cgroup
328 * group. Protected by css_set_lock
330 struct list_head tasks;
333 * List of cgrp_cset_links pointing at cgroups referenced from this
334 * css_set. Protected by css_set_lock.
336 struct list_head cgrp_links;
339 * Set of subsystem states, one for each subsystem. This array is
340 * immutable after creation apart from the init_css_set during
341 * subsystem registration (at boot time).
343 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
345 /* For RCU-protected deletion */
346 struct rcu_head rcu_head;
350 * struct cftype: handler definitions for cgroup control files
352 * When reading/writing to a file:
353 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata
354 * - the 'cftype' of the file is file->f_dentry->d_fsdata
359 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
360 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
361 CFTYPE_INSANE = (1 << 2), /* don't create if sane_behavior */
362 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
365 #define MAX_CFTYPE_NAME 64
369 * By convention, the name should begin with the name of the
370 * subsystem, followed by a period. Zero length string indicates
371 * end of cftype array.
373 char name[MAX_CFTYPE_NAME];
376 * If not 0, file mode is set to this value, otherwise it will
377 * be figured out automatically
382 * The maximum length of string, excluding trailing nul, that can
383 * be passed to write_string. If < PAGE_SIZE-1, PAGE_SIZE-1 is
386 size_t max_write_len;
392 * Fields used for internal bookkeeping. Initialized automatically
393 * during registration.
395 struct cgroup_subsys *ss; /* NULL for cgroup core files */
396 struct list_head node; /* anchored at ss->cfts */
397 struct kernfs_ops *kf_ops;
400 * read_u64() is a shortcut for the common case of returning a
401 * single integer. Use it in place of read()
403 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
405 * read_s64() is a signed version of read_u64()
407 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
409 /* generic seq_file read interface */
410 int (*seq_show)(struct seq_file *sf, void *v);
412 /* optional ops, implement all or none */
413 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
414 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
415 void (*seq_stop)(struct seq_file *sf, void *v);
418 * write_u64() is a shortcut for the common case of accepting
419 * a single integer (as parsed by simple_strtoull) from
420 * userspace. Use in place of write(); return 0 or error.
422 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
425 * write_s64() is a signed version of write_u64()
427 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
431 * write_string() is passed a nul-terminated kernelspace
432 * buffer of maximum length determined by max_write_len.
433 * Returns 0 or -ve error code.
435 int (*write_string)(struct cgroup_subsys_state *css, struct cftype *cft,
438 * trigger() callback can be used to get some kick from the
439 * userspace, when the actual string written is not important
440 * at all. The private field can be used to determine the
441 * kick type for multiplexing.
443 int (*trigger)(struct cgroup_subsys_state *css, unsigned int event);
445 #ifdef CONFIG_DEBUG_LOCK_ALLOC
446 struct lock_class_key lockdep_key;
451 * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This
452 * function can be called as long as @cgrp is accessible.
454 static inline bool cgroup_sane_behavior(const struct cgroup *cgrp)
456 return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR;
459 /* no synchronization, the result can only be used as a hint */
460 static inline bool cgroup_has_tasks(struct cgroup *cgrp)
462 return !list_empty(&cgrp->cset_links);
465 /* returns ino associated with a cgroup, 0 indicates unmounted root */
466 static inline ino_t cgroup_ino(struct cgroup *cgrp)
469 return cgrp->kn->ino;
474 static inline struct cftype *seq_cft(struct seq_file *seq)
476 struct kernfs_open_file *of = seq->private;
481 struct cgroup_subsys_state *seq_css(struct seq_file *seq);
484 * Name / path handling functions. All are thin wrappers around the kernfs
485 * counterparts and can be called under any context.
488 static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
490 return kernfs_name(cgrp->kn, buf, buflen);
493 static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
496 return kernfs_path(cgrp->kn, buf, buflen);
499 static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
501 /* dummy_top doesn't have a kn associated */
503 pr_cont_kernfs_name(cgrp->kn);
508 static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
510 /* dummy_top doesn't have a kn associated */
512 pr_cont_kernfs_path(cgrp->kn);
517 char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
519 int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
520 int cgroup_rm_cftypes(struct cftype *cfts);
522 bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
525 * Control Group taskset, used to pass around set of tasks to cgroup_subsys
528 struct cgroup_taskset;
529 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
530 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
531 struct cgroup_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset,
533 int cgroup_taskset_size(struct cgroup_taskset *tset);
536 * cgroup_taskset_for_each - iterate cgroup_taskset
537 * @task: the loop cursor
538 * @skip_css: skip if task's css matches this, %NULL to iterate through all
539 * @tset: taskset to iterate
541 #define cgroup_taskset_for_each(task, skip_css, tset) \
542 for ((task) = cgroup_taskset_first((tset)); (task); \
543 (task) = cgroup_taskset_next((tset))) \
545 cgroup_taskset_cur_css((tset), \
546 (skip_css)->ss->id) != (skip_css))
549 * Control Group subsystem type.
550 * See Documentation/cgroups/cgroups.txt for details
553 struct cgroup_subsys {
554 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
555 int (*css_online)(struct cgroup_subsys_state *css);
556 void (*css_offline)(struct cgroup_subsys_state *css);
557 void (*css_free)(struct cgroup_subsys_state *css);
559 int (*can_attach)(struct cgroup_subsys_state *css,
560 struct cgroup_taskset *tset);
561 void (*cancel_attach)(struct cgroup_subsys_state *css,
562 struct cgroup_taskset *tset);
563 void (*attach)(struct cgroup_subsys_state *css,
564 struct cgroup_taskset *tset);
565 void (*fork)(struct task_struct *task);
566 void (*exit)(struct cgroup_subsys_state *css,
567 struct cgroup_subsys_state *old_css,
568 struct task_struct *task);
569 void (*bind)(struct cgroup_subsys_state *root_css);
575 * If %false, this subsystem is properly hierarchical -
576 * configuration, resource accounting and restriction on a parent
577 * cgroup cover those of its children. If %true, hierarchy support
578 * is broken in some ways - some subsystems ignore hierarchy
579 * completely while others are only implemented half-way.
581 * It's now disallowed to create nested cgroups if the subsystem is
582 * broken and cgroup core will emit a warning message on such
583 * cases. Eventually, all subsystems will be made properly
584 * hierarchical and this will go away.
586 bool broken_hierarchy;
587 bool warned_broken_hierarchy;
589 /* the following two fields are initialized automtically during boot */
591 #define MAX_CGROUP_TYPE_NAMELEN 32
594 /* link to parent, protected by cgroup_lock() */
595 struct cgroupfs_root *root;
598 * List of cftypes. Each entry is the first entry of an array
599 * terminated by zero length name.
601 struct list_head cfts;
603 /* base cftypes, automatically registered with subsys itself */
604 struct cftype *base_cftypes;
607 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
608 #include <linux/cgroup_subsys.h>
612 * css_parent - find the parent css
613 * @css: the target cgroup_subsys_state
615 * Return the parent css of @css. This function is guaranteed to return
616 * non-NULL parent as long as @css isn't the root.
619 struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css)
625 * task_css_set_check - obtain a task's css_set with extra access conditions
626 * @task: the task to obtain css_set for
627 * @__c: extra condition expression to be passed to rcu_dereference_check()
629 * A task's css_set is RCU protected, initialized and exited while holding
630 * task_lock(), and can only be modified while holding both cgroup_mutex
631 * and task_lock() while the task is alive. This macro verifies that the
632 * caller is inside proper critical section and returns @task's css_set.
634 * The caller can also specify additional allowed conditions via @__c, such
635 * as locks used during the cgroup_subsys::attach() methods.
637 #ifdef CONFIG_PROVE_RCU
638 extern struct mutex cgroup_mutex;
639 #define task_css_set_check(task, __c) \
640 rcu_dereference_check((task)->cgroups, \
641 lockdep_is_held(&(task)->alloc_lock) || \
642 lockdep_is_held(&cgroup_mutex) || (__c))
644 #define task_css_set_check(task, __c) \
645 rcu_dereference((task)->cgroups)
649 * task_css_check - obtain css for (task, subsys) w/ extra access conds
650 * @task: the target task
651 * @subsys_id: the target subsystem ID
652 * @__c: extra condition expression to be passed to rcu_dereference_check()
654 * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The
655 * synchronization rules are the same as task_css_set_check().
657 #define task_css_check(task, subsys_id, __c) \
658 task_css_set_check((task), (__c))->subsys[(subsys_id)]
661 * task_css_set - obtain a task's css_set
662 * @task: the task to obtain css_set for
664 * See task_css_set_check().
666 static inline struct css_set *task_css_set(struct task_struct *task)
668 return task_css_set_check(task, false);
672 * task_css - obtain css for (task, subsys)
673 * @task: the target task
674 * @subsys_id: the target subsystem ID
676 * See task_css_check().
678 static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
681 return task_css_check(task, subsys_id, false);
684 static inline struct cgroup *task_cgroup(struct task_struct *task,
687 return task_css(task, subsys_id)->cgroup;
690 struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
691 struct cgroup_subsys_state *parent);
693 struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
696 * css_for_each_child - iterate through children of a css
697 * @pos: the css * to use as the loop cursor
698 * @parent: css whose children to walk
700 * Walk @parent's children. Must be called under rcu_read_lock(). A child
701 * css which hasn't finished ->css_online() or already has finished
702 * ->css_offline() may show up during traversal and it's each subsystem's
703 * responsibility to verify that each @pos is alive.
705 * If a subsystem synchronizes against the parent in its ->css_online() and
706 * before starting iterating, a css which finished ->css_online() is
707 * guaranteed to be visible in the future iterations.
709 * It is allowed to temporarily drop RCU read lock during iteration. The
710 * caller is responsible for ensuring that @pos remains accessible until
711 * the start of the next iteration by, for example, bumping the css refcnt.
713 #define css_for_each_child(pos, parent) \
714 for ((pos) = css_next_child(NULL, (parent)); (pos); \
715 (pos) = css_next_child((pos), (parent)))
717 struct cgroup_subsys_state *
718 css_next_descendant_pre(struct cgroup_subsys_state *pos,
719 struct cgroup_subsys_state *css);
721 struct cgroup_subsys_state *
722 css_rightmost_descendant(struct cgroup_subsys_state *pos);
725 * css_for_each_descendant_pre - pre-order walk of a css's descendants
726 * @pos: the css * to use as the loop cursor
727 * @root: css whose descendants to walk
729 * Walk @root's descendants. @root is included in the iteration and the
730 * first node to be visited. Must be called under rcu_read_lock(). A
731 * descendant css which hasn't finished ->css_online() or already has
732 * finished ->css_offline() may show up during traversal and it's each
733 * subsystem's responsibility to verify that each @pos is alive.
735 * If a subsystem synchronizes against the parent in its ->css_online() and
736 * before starting iterating, and synchronizes against @pos on each
737 * iteration, any descendant css which finished ->css_online() is
738 * guaranteed to be visible in the future iterations.
740 * In other words, the following guarantees that a descendant can't escape
741 * state updates of its ancestors.
745 * Lock @css's parent and @css;
746 * Inherit state from the parent;
750 * my_update_state(@css)
752 * css_for_each_descendant_pre(@pos, @css) {
755 * Update @css's state;
757 * Verify @pos is alive and inherit state from its parent;
762 * As long as the inheriting step, including checking the parent state, is
763 * enclosed inside @pos locking, double-locking the parent isn't necessary
764 * while inheriting. The state update to the parent is guaranteed to be
765 * visible by walking order and, as long as inheriting operations to the
766 * same @pos are atomic to each other, multiple updates racing each other
767 * still result in the correct state. It's guaranateed that at least one
768 * inheritance happens for any css after the latest update to its parent.
770 * If checking parent's state requires locking the parent, each inheriting
771 * iteration should lock and unlock both @pos->parent and @pos.
773 * Alternatively, a subsystem may choose to use a single global lock to
774 * synchronize ->css_online() and ->css_offline() against tree-walking
777 * It is allowed to temporarily drop RCU read lock during iteration. The
778 * caller is responsible for ensuring that @pos remains accessible until
779 * the start of the next iteration by, for example, bumping the css refcnt.
781 #define css_for_each_descendant_pre(pos, css) \
782 for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \
783 (pos) = css_next_descendant_pre((pos), (css)))
785 struct cgroup_subsys_state *
786 css_next_descendant_post(struct cgroup_subsys_state *pos,
787 struct cgroup_subsys_state *css);
790 * css_for_each_descendant_post - post-order walk of a css's descendants
791 * @pos: the css * to use as the loop cursor
792 * @css: css whose descendants to walk
794 * Similar to css_for_each_descendant_pre() but performs post-order
795 * traversal instead. @root is included in the iteration and the last
796 * node to be visited. Note that the walk visibility guarantee described
797 * in pre-order walk doesn't apply the same to post-order walks.
799 #define css_for_each_descendant_post(pos, css) \
800 for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
801 (pos) = css_next_descendant_post((pos), (css)))
803 /* A css_task_iter should be treated as an opaque object */
804 struct css_task_iter {
805 struct cgroup_subsys_state *origin_css;
806 struct list_head *cset_link;
807 struct list_head *task;
810 void css_task_iter_start(struct cgroup_subsys_state *css,
811 struct css_task_iter *it);
812 struct task_struct *css_task_iter_next(struct css_task_iter *it);
813 void css_task_iter_end(struct css_task_iter *it);
815 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
816 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
818 struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry,
819 struct cgroup_subsys *ss);
821 #else /* !CONFIG_CGROUPS */
823 static inline int cgroup_init_early(void) { return 0; }
824 static inline int cgroup_init(void) { return 0; }
825 static inline void cgroup_fork(struct task_struct *p) {}
826 static inline void cgroup_post_fork(struct task_struct *p) {}
827 static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
829 static inline int cgroupstats_build(struct cgroupstats *stats,
830 struct dentry *dentry)
835 /* No cgroups - nothing to do */
836 static inline int cgroup_attach_task_all(struct task_struct *from,
837 struct task_struct *t)
842 #endif /* !CONFIG_CGROUPS */
844 #endif /* _LINUX_CGROUP_H */