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/prio_heap.h>
18 #include <linux/rwsem.h>
19 #include <linux/idr.h>
20 #include <linux/workqueue.h>
22 #include <linux/percpu-refcount.h>
23 #include <linux/seq_file.h>
24 #include <linux/kernfs.h>
33 extern int cgroup_init_early(void);
34 extern int cgroup_init(void);
35 extern void cgroup_fork(struct task_struct *p);
36 extern void cgroup_post_fork(struct task_struct *p);
37 extern void cgroup_exit(struct task_struct *p, int run_callbacks);
38 extern int cgroupstats_build(struct cgroupstats *stats,
39 struct dentry *dentry);
41 extern int proc_cgroup_show(struct seq_file *, void *);
43 /* define the enumeration of all cgroup subsystems */
44 #define SUBSYS(_x) _x ## _cgrp_id,
45 enum cgroup_subsys_id {
46 #include <linux/cgroup_subsys.h>
51 /* Per-subsystem/per-cgroup state maintained by the system. */
52 struct cgroup_subsys_state {
53 /* the cgroup that this css is attached to */
54 struct cgroup *cgroup;
56 /* the cgroup subsystem that this css is attached to */
57 struct cgroup_subsys *ss;
59 /* reference count - access via css_[try]get() and css_put() */
60 struct percpu_ref refcnt;
63 struct cgroup_subsys_state *parent;
67 /* percpu_ref killing and RCU release */
68 struct rcu_head rcu_head;
69 struct work_struct destroy_work;
72 /* bits in struct cgroup_subsys_state flags field */
74 CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */
75 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
79 * css_get - obtain a reference on the specified css
82 * The caller must already have a reference.
84 static inline void css_get(struct cgroup_subsys_state *css)
86 /* We don't need to reference count the root state */
87 if (!(css->flags & CSS_ROOT))
88 percpu_ref_get(&css->refcnt);
92 * css_tryget - try to obtain a reference on the specified css
95 * Obtain a reference on @css if it's alive. The caller naturally needs to
96 * ensure that @css is accessible but doesn't have to be holding a
97 * reference on it - IOW, RCU protected access is good enough for this
98 * function. Returns %true if a reference count was successfully obtained;
101 static inline bool css_tryget(struct cgroup_subsys_state *css)
103 if (css->flags & CSS_ROOT)
105 return percpu_ref_tryget(&css->refcnt);
109 * css_put - put a css reference
112 * Put a reference obtained via css_get() and css_tryget().
114 static inline void css_put(struct cgroup_subsys_state *css)
116 if (!(css->flags & CSS_ROOT))
117 percpu_ref_put(&css->refcnt);
120 /* bits in struct cgroup flags field */
122 /* Control Group is dead */
125 * Control Group has previously had a child cgroup or a task,
126 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
129 /* Control Group requires release notifications to userspace */
130 CGRP_NOTIFY_ON_RELEASE,
132 * Clone the parent's configuration when creating a new child
133 * cpuset cgroup. For historical reasons, this option can be
134 * specified at mount time and thus is implemented here.
136 CGRP_CPUSET_CLONE_CHILDREN,
137 /* see the comment above CGRP_ROOT_SANE_BEHAVIOR for details */
142 unsigned long flags; /* "unsigned long" so bitops work */
145 * idr allocated in-hierarchy ID.
147 * The ID of the root cgroup is always 0, and a new cgroup
148 * will be assigned with a smallest available ID.
150 * Allocating/Removing ID must be protected by cgroup_mutex.
154 /* the number of attached css's */
160 * We link our 'sibling' struct into our parent's 'children'.
161 * Our children link their 'sibling' into our 'children'.
163 struct list_head sibling; /* my parent's children */
164 struct list_head children; /* my children */
166 struct cgroup *parent; /* my parent */
167 struct kernfs_node *kn; /* cgroup kernfs entry */
170 * Monotonically increasing unique serial number which defines a
171 * uniform order among all cgroups. It's guaranteed that all
172 * ->children lists are in the ascending order of ->serial_nr.
173 * It's used to allow interrupting and resuming iterations.
177 /* Private pointers for each registered subsystem */
178 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
180 struct cgroupfs_root *root;
183 * List of cgrp_cset_links pointing at css_sets with tasks in this
184 * cgroup. Protected by css_set_lock.
186 struct list_head cset_links;
189 * Linked list running through all cgroups that can
190 * potentially be reaped by the release agent. Protected by
193 struct list_head release_list;
196 * list of pidlists, up to two for each namespace (one for procs, one
197 * for tasks); created on demand.
199 struct list_head pidlists;
200 struct mutex pidlist_mutex;
202 /* dummy css with NULL ->ss, points back to this cgroup */
203 struct cgroup_subsys_state dummy_css;
205 /* For css percpu_ref killing and RCU-protected deletion */
206 struct rcu_head rcu_head;
207 struct work_struct destroy_work;
210 #define MAX_CGROUP_ROOT_NAMELEN 64
212 /* cgroupfs_root->flags */
215 * Unfortunately, cgroup core and various controllers are riddled
216 * with idiosyncrasies and pointless options. The following flag,
217 * when set, will force sane behavior - some options are forced on,
218 * others are disallowed, and some controllers will change their
219 * hierarchical or other behaviors.
221 * The set of behaviors affected by this flag are still being
222 * determined and developed and the mount option for this flag is
223 * prefixed with __DEVEL__. The prefix will be dropped once we
224 * reach the point where all behaviors are compatible with the
225 * planned unified hierarchy, which will automatically turn on this
228 * The followings are the behaviors currently affected this flag.
230 * - Mount options "noprefix", "xattr", "clone_children",
231 * "release_agent" and "name" are disallowed.
233 * - When mounting an existing superblock, mount options should
236 * - Remount is disallowed.
238 * - rename(2) is disallowed.
240 * - "tasks" is removed. Everything should be at process
241 * granularity. Use "cgroup.procs" instead.
243 * - "cgroup.procs" is not sorted. pids will be unique unless they
244 * got recycled inbetween reads.
246 * - "release_agent" and "notify_on_release" are removed.
247 * Replacement notification mechanism will be implemented.
249 * - "cgroup.clone_children" is removed.
251 * - cpuset: tasks will be kept in empty cpusets when hotplug happens
252 * and take masks of ancestors with non-empty cpus/mems, instead of
253 * being moved to an ancestor.
255 * - cpuset: a task can be moved into an empty cpuset, and again it
256 * takes masks of ancestors.
258 * - memcg: use_hierarchy is on by default and the cgroup file for
259 * the flag is not created.
261 * - blkcg: blk-throttle becomes properly hierarchical.
263 CGRP_ROOT_SANE_BEHAVIOR = (1 << 0),
265 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
266 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
268 /* mount options live below bit 16 */
269 CGRP_ROOT_OPTION_MASK = (1 << 16) - 1,
273 * A cgroupfs_root represents the root of a cgroup hierarchy, and may be
274 * associated with a kernfs_root to form an active hierarchy. This is
275 * internal to cgroup core. Don't access directly from controllers.
277 struct cgroupfs_root {
278 struct kernfs_root *kf_root;
280 /* The bitmask of subsystems attached to this hierarchy */
281 unsigned long subsys_mask;
283 /* Unique id for this hierarchy. */
286 /* The root cgroup. Root is destroyed on its release. */
287 struct cgroup top_cgroup;
289 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
292 /* A list running through the active hierarchies */
293 struct list_head root_list;
295 /* Hierarchy-specific flags */
298 /* IDs for cgroups in this hierarchy */
299 struct idr cgroup_idr;
301 /* The path to use for release notifications. */
302 char release_agent_path[PATH_MAX];
304 /* The name for this hierarchy - may be empty */
305 char name[MAX_CGROUP_ROOT_NAMELEN];
309 * A css_set is a structure holding pointers to a set of
310 * cgroup_subsys_state objects. This saves space in the task struct
311 * object and speeds up fork()/exit(), since a single inc/dec and a
312 * list_add()/del() can bump the reference count on the entire cgroup
318 /* Reference count */
322 * List running through all cgroup groups in the same hash
323 * slot. Protected by css_set_lock
325 struct hlist_node hlist;
328 * List running through all tasks using this cgroup
329 * group. Protected by css_set_lock
331 struct list_head tasks;
334 * List of cgrp_cset_links pointing at cgroups referenced from this
335 * css_set. Protected by css_set_lock.
337 struct list_head cgrp_links;
340 * Set of subsystem states, one for each subsystem. This array is
341 * immutable after creation apart from the init_css_set during
342 * subsystem registration (at boot time).
344 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
346 /* For RCU-protected deletion */
347 struct rcu_head rcu_head;
351 * struct cftype: handler definitions for cgroup control files
353 * When reading/writing to a file:
354 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata
355 * - the 'cftype' of the file is file->f_dentry->d_fsdata
360 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
361 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
362 CFTYPE_INSANE = (1 << 2), /* don't create if sane_behavior */
363 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
366 #define MAX_CFTYPE_NAME 64
370 * By convention, the name should begin with the name of the
371 * subsystem, followed by a period. Zero length string indicates
372 * end of cftype array.
374 char name[MAX_CFTYPE_NAME];
377 * If not 0, file mode is set to this value, otherwise it will
378 * be figured out automatically
383 * The maximum length of string, excluding trailing nul, that can
384 * be passed to write_string. If < PAGE_SIZE-1, PAGE_SIZE-1 is
387 size_t max_write_len;
393 * Fields used for internal bookkeeping. Initialized automatically
394 * during registration.
396 struct cgroup_subsys *ss; /* NULL for cgroup core files */
397 struct list_head node; /* anchored at ss->cfts */
398 struct kernfs_ops *kf_ops;
401 * read_u64() is a shortcut for the common case of returning a
402 * single integer. Use it in place of read()
404 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
406 * read_s64() is a signed version of read_u64()
408 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
410 /* generic seq_file read interface */
411 int (*seq_show)(struct seq_file *sf, void *v);
413 /* optional ops, implement all or none */
414 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
415 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
416 void (*seq_stop)(struct seq_file *sf, void *v);
419 * write_u64() is a shortcut for the common case of accepting
420 * a single integer (as parsed by simple_strtoull) from
421 * userspace. Use in place of write(); return 0 or error.
423 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
426 * write_s64() is a signed version of write_u64()
428 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
432 * write_string() is passed a nul-terminated kernelspace
433 * buffer of maximum length determined by max_write_len.
434 * Returns 0 or -ve error code.
436 int (*write_string)(struct cgroup_subsys_state *css, struct cftype *cft,
439 * trigger() callback can be used to get some kick from the
440 * userspace, when the actual string written is not important
441 * at all. The private field can be used to determine the
442 * kick type for multiplexing.
444 int (*trigger)(struct cgroup_subsys_state *css, unsigned int event);
446 #ifdef CONFIG_DEBUG_LOCK_ALLOC
447 struct lock_class_key lockdep_key;
452 * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This
453 * function can be called as long as @cgrp is accessible.
455 static inline bool cgroup_sane_behavior(const struct cgroup *cgrp)
457 return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR;
460 /* returns ino associated with a cgroup, 0 indicates unmounted root */
461 static inline ino_t cgroup_ino(struct cgroup *cgrp)
464 return cgrp->kn->ino;
469 static inline struct cftype *seq_cft(struct seq_file *seq)
471 struct kernfs_open_file *of = seq->private;
476 struct cgroup_subsys_state *seq_css(struct seq_file *seq);
479 * Name / path handling functions. All are thin wrappers around the kernfs
480 * counterparts and can be called under any context.
483 static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
485 return kernfs_name(cgrp->kn, buf, buflen);
488 static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
491 return kernfs_path(cgrp->kn, buf, buflen);
494 static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
496 /* dummy_top doesn't have a kn associated */
498 pr_cont_kernfs_name(cgrp->kn);
503 static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
505 /* dummy_top doesn't have a kn associated */
507 pr_cont_kernfs_path(cgrp->kn);
512 char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
514 int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
515 int cgroup_rm_cftypes(struct cftype *cfts);
517 bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
519 int cgroup_task_count(const struct cgroup *cgrp);
522 * Control Group taskset, used to pass around set of tasks to cgroup_subsys
525 struct cgroup_taskset;
526 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
527 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
528 struct cgroup_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset,
530 int cgroup_taskset_size(struct cgroup_taskset *tset);
533 * cgroup_taskset_for_each - iterate cgroup_taskset
534 * @task: the loop cursor
535 * @skip_css: skip if task's css matches this, %NULL to iterate through all
536 * @tset: taskset to iterate
538 #define cgroup_taskset_for_each(task, skip_css, tset) \
539 for ((task) = cgroup_taskset_first((tset)); (task); \
540 (task) = cgroup_taskset_next((tset))) \
542 cgroup_taskset_cur_css((tset), \
543 (skip_css)->ss->id) != (skip_css))
546 * Control Group subsystem type.
547 * See Documentation/cgroups/cgroups.txt for details
550 struct cgroup_subsys {
551 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
552 int (*css_online)(struct cgroup_subsys_state *css);
553 void (*css_offline)(struct cgroup_subsys_state *css);
554 void (*css_free)(struct cgroup_subsys_state *css);
556 int (*can_attach)(struct cgroup_subsys_state *css,
557 struct cgroup_taskset *tset);
558 void (*cancel_attach)(struct cgroup_subsys_state *css,
559 struct cgroup_taskset *tset);
560 void (*attach)(struct cgroup_subsys_state *css,
561 struct cgroup_taskset *tset);
562 void (*fork)(struct task_struct *task);
563 void (*exit)(struct cgroup_subsys_state *css,
564 struct cgroup_subsys_state *old_css,
565 struct task_struct *task);
566 void (*bind)(struct cgroup_subsys_state *root_css);
572 * If %false, this subsystem is properly hierarchical -
573 * configuration, resource accounting and restriction on a parent
574 * cgroup cover those of its children. If %true, hierarchy support
575 * is broken in some ways - some subsystems ignore hierarchy
576 * completely while others are only implemented half-way.
578 * It's now disallowed to create nested cgroups if the subsystem is
579 * broken and cgroup core will emit a warning message on such
580 * cases. Eventually, all subsystems will be made properly
581 * hierarchical and this will go away.
583 bool broken_hierarchy;
584 bool warned_broken_hierarchy;
586 /* the following two fields are initialized automtically during boot */
588 #define MAX_CGROUP_TYPE_NAMELEN 32
591 /* link to parent, protected by cgroup_lock() */
592 struct cgroupfs_root *root;
595 * List of cftypes. Each entry is the first entry of an array
596 * terminated by zero length name.
598 struct list_head cfts;
600 /* base cftypes, automatically registered with subsys itself */
601 struct cftype *base_cftypes;
604 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
605 #include <linux/cgroup_subsys.h>
609 * css_parent - find the parent css
610 * @css: the target cgroup_subsys_state
612 * Return the parent css of @css. This function is guaranteed to return
613 * non-NULL parent as long as @css isn't the root.
616 struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css)
622 * task_css_set_check - obtain a task's css_set with extra access conditions
623 * @task: the task to obtain css_set for
624 * @__c: extra condition expression to be passed to rcu_dereference_check()
626 * A task's css_set is RCU protected, initialized and exited while holding
627 * task_lock(), and can only be modified while holding both cgroup_mutex
628 * and task_lock() while the task is alive. This macro verifies that the
629 * caller is inside proper critical section and returns @task's css_set.
631 * The caller can also specify additional allowed conditions via @__c, such
632 * as locks used during the cgroup_subsys::attach() methods.
634 #ifdef CONFIG_PROVE_RCU
635 extern struct mutex cgroup_mutex;
636 #define task_css_set_check(task, __c) \
637 rcu_dereference_check((task)->cgroups, \
638 lockdep_is_held(&(task)->alloc_lock) || \
639 lockdep_is_held(&cgroup_mutex) || (__c))
641 #define task_css_set_check(task, __c) \
642 rcu_dereference((task)->cgroups)
646 * task_css_check - obtain css for (task, subsys) w/ extra access conds
647 * @task: the target task
648 * @subsys_id: the target subsystem ID
649 * @__c: extra condition expression to be passed to rcu_dereference_check()
651 * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The
652 * synchronization rules are the same as task_css_set_check().
654 #define task_css_check(task, subsys_id, __c) \
655 task_css_set_check((task), (__c))->subsys[(subsys_id)]
658 * task_css_set - obtain a task's css_set
659 * @task: the task to obtain css_set for
661 * See task_css_set_check().
663 static inline struct css_set *task_css_set(struct task_struct *task)
665 return task_css_set_check(task, false);
669 * task_css - obtain css for (task, subsys)
670 * @task: the target task
671 * @subsys_id: the target subsystem ID
673 * See task_css_check().
675 static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
678 return task_css_check(task, subsys_id, false);
681 static inline struct cgroup *task_cgroup(struct task_struct *task,
684 return task_css(task, subsys_id)->cgroup;
687 struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
688 struct cgroup_subsys_state *parent);
690 struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
693 * css_for_each_child - iterate through children of a css
694 * @pos: the css * to use as the loop cursor
695 * @parent: css whose children to walk
697 * Walk @parent's children. Must be called under rcu_read_lock(). A child
698 * css which hasn't finished ->css_online() or already has finished
699 * ->css_offline() may show up during traversal and it's each subsystem's
700 * responsibility to verify that each @pos is alive.
702 * If a subsystem synchronizes against the parent in its ->css_online() and
703 * before starting iterating, a css which finished ->css_online() is
704 * guaranteed to be visible in the future iterations.
706 * It is allowed to temporarily drop RCU read lock during iteration. The
707 * caller is responsible for ensuring that @pos remains accessible until
708 * the start of the next iteration by, for example, bumping the css refcnt.
710 #define css_for_each_child(pos, parent) \
711 for ((pos) = css_next_child(NULL, (parent)); (pos); \
712 (pos) = css_next_child((pos), (parent)))
714 struct cgroup_subsys_state *
715 css_next_descendant_pre(struct cgroup_subsys_state *pos,
716 struct cgroup_subsys_state *css);
718 struct cgroup_subsys_state *
719 css_rightmost_descendant(struct cgroup_subsys_state *pos);
722 * css_for_each_descendant_pre - pre-order walk of a css's descendants
723 * @pos: the css * to use as the loop cursor
724 * @root: css whose descendants to walk
726 * Walk @root's descendants. @root is included in the iteration and the
727 * first node to be visited. Must be called under rcu_read_lock(). A
728 * descendant css which hasn't finished ->css_online() or already has
729 * finished ->css_offline() may show up during traversal and it's each
730 * subsystem's responsibility to verify that each @pos is alive.
732 * If a subsystem synchronizes against the parent in its ->css_online() and
733 * before starting iterating, and synchronizes against @pos on each
734 * iteration, any descendant css which finished ->css_online() is
735 * guaranteed to be visible in the future iterations.
737 * In other words, the following guarantees that a descendant can't escape
738 * state updates of its ancestors.
742 * Lock @css's parent and @css;
743 * Inherit state from the parent;
747 * my_update_state(@css)
749 * css_for_each_descendant_pre(@pos, @css) {
752 * Update @css's state;
754 * Verify @pos is alive and inherit state from its parent;
759 * As long as the inheriting step, including checking the parent state, is
760 * enclosed inside @pos locking, double-locking the parent isn't necessary
761 * while inheriting. The state update to the parent is guaranteed to be
762 * visible by walking order and, as long as inheriting operations to the
763 * same @pos are atomic to each other, multiple updates racing each other
764 * still result in the correct state. It's guaranateed that at least one
765 * inheritance happens for any css after the latest update to its parent.
767 * If checking parent's state requires locking the parent, each inheriting
768 * iteration should lock and unlock both @pos->parent and @pos.
770 * Alternatively, a subsystem may choose to use a single global lock to
771 * synchronize ->css_online() and ->css_offline() against tree-walking
774 * It is allowed to temporarily drop RCU read lock during iteration. The
775 * caller is responsible for ensuring that @pos remains accessible until
776 * the start of the next iteration by, for example, bumping the css refcnt.
778 #define css_for_each_descendant_pre(pos, css) \
779 for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \
780 (pos) = css_next_descendant_pre((pos), (css)))
782 struct cgroup_subsys_state *
783 css_next_descendant_post(struct cgroup_subsys_state *pos,
784 struct cgroup_subsys_state *css);
787 * css_for_each_descendant_post - post-order walk of a css's descendants
788 * @pos: the css * to use as the loop cursor
789 * @css: css whose descendants to walk
791 * Similar to css_for_each_descendant_pre() but performs post-order
792 * traversal instead. @root is included in the iteration and the last
793 * node to be visited. Note that the walk visibility guarantee described
794 * in pre-order walk doesn't apply the same to post-order walks.
796 #define css_for_each_descendant_post(pos, css) \
797 for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
798 (pos) = css_next_descendant_post((pos), (css)))
800 /* A css_task_iter should be treated as an opaque object */
801 struct css_task_iter {
802 struct cgroup_subsys_state *origin_css;
803 struct list_head *cset_link;
804 struct list_head *task;
807 void css_task_iter_start(struct cgroup_subsys_state *css,
808 struct css_task_iter *it);
809 struct task_struct *css_task_iter_next(struct css_task_iter *it);
810 void css_task_iter_end(struct css_task_iter *it);
812 int css_scan_tasks(struct cgroup_subsys_state *css,
813 bool (*test)(struct task_struct *, void *),
814 void (*process)(struct task_struct *, void *),
815 void *data, struct ptr_heap *heap);
817 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
818 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
820 struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry,
821 struct cgroup_subsys *ss);
823 #else /* !CONFIG_CGROUPS */
825 static inline int cgroup_init_early(void) { return 0; }
826 static inline int cgroup_init(void) { return 0; }
827 static inline void cgroup_fork(struct task_struct *p) {}
828 static inline void cgroup_post_fork(struct task_struct *p) {}
829 static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
831 static inline int cgroupstats_build(struct cgroupstats *stats,
832 struct dentry *dentry)
837 /* No cgroups - nothing to do */
838 static inline int cgroup_attach_task_all(struct task_struct *from,
839 struct task_struct *t)
844 #endif /* !CONFIG_CGROUPS */
846 #endif /* _LINUX_CGROUP_H */