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>
21 #include <linux/xattr.h>
23 #include <linux/percpu-refcount.h>
24 #include <linux/seq_file.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 struct rcu_head rcu_head;
147 unsigned long flags; /* "unsigned long" so bitops work */
150 * idr allocated in-hierarchy ID.
152 * The ID of the root cgroup is always 0, and a new cgroup
153 * will be assigned with a smallest available ID.
157 /* the number of attached css's */
161 * We link our 'sibling' struct into our parent's 'children'.
162 * Our children link their 'sibling' into our 'children'.
164 struct list_head sibling; /* my parent's children */
165 struct list_head children; /* my children */
166 struct list_head files; /* my files */
168 struct cgroup *parent; /* my parent */
169 struct dentry *dentry; /* cgroup fs entry, RCU protected */
172 * Monotonically increasing unique serial number which defines a
173 * uniform order among all cgroups. It's guaranteed that all
174 * ->children lists are in the ascending order of ->serial_nr.
175 * It's used to allow interrupting and resuming iterations.
180 * This is a copy of dentry->d_name, and it's needed because
181 * we can't use dentry->d_name in cgroup_path().
183 * You must acquire rcu_read_lock() to access cgrp->name, and
184 * the only place that can change it is rename(), which is
185 * protected by parent dir's i_mutex.
187 * Normally you should use cgroup_name() wrapper rather than
188 * access it directly.
190 struct cgroup_name __rcu *name;
192 /* Private pointers for each registered subsystem */
193 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
195 struct cgroupfs_root *root;
198 * List of cgrp_cset_links pointing at css_sets with tasks in this
199 * cgroup. Protected by css_set_lock.
201 struct list_head cset_links;
204 * Linked list running through all cgroups that can
205 * potentially be reaped by the release agent. Protected by
208 struct list_head release_list;
211 * list of pidlists, up to two for each namespace (one for procs, one
212 * for tasks); created on demand.
214 struct list_head pidlists;
215 struct mutex pidlist_mutex;
217 /* dummy css with NULL ->ss, points back to this cgroup */
218 struct cgroup_subsys_state dummy_css;
220 /* For css percpu_ref killing and RCU-protected deletion */
221 struct rcu_head rcu_head;
222 struct work_struct destroy_work;
224 /* directory xattrs */
225 struct simple_xattrs xattrs;
228 #define MAX_CGROUP_ROOT_NAMELEN 64
230 /* cgroupfs_root->flags */
233 * Unfortunately, cgroup core and various controllers are riddled
234 * with idiosyncrasies and pointless options. The following flag,
235 * when set, will force sane behavior - some options are forced on,
236 * others are disallowed, and some controllers will change their
237 * hierarchical or other behaviors.
239 * The set of behaviors affected by this flag are still being
240 * determined and developed and the mount option for this flag is
241 * prefixed with __DEVEL__. The prefix will be dropped once we
242 * reach the point where all behaviors are compatible with the
243 * planned unified hierarchy, which will automatically turn on this
246 * The followings are the behaviors currently affected this flag.
248 * - Mount options "noprefix" and "clone_children" are disallowed.
249 * Also, cgroupfs file cgroup.clone_children is not created.
251 * - When mounting an existing superblock, mount options should
254 * - Remount is disallowed.
256 * - rename(2) is disallowed.
258 * - "tasks" is removed. Everything should be at process
259 * granularity. Use "cgroup.procs" instead.
261 * - "cgroup.procs" is not sorted. pids will be unique unless they
262 * got recycled inbetween reads.
264 * - "release_agent" and "notify_on_release" are removed.
265 * Replacement notification mechanism will be implemented.
267 * - cpuset: tasks will be kept in empty cpusets when hotplug happens
268 * and take masks of ancestors with non-empty cpus/mems, instead of
269 * being moved to an ancestor.
271 * - cpuset: a task can be moved into an empty cpuset, and again it
272 * takes masks of ancestors.
274 * - memcg: use_hierarchy is on by default and the cgroup file for
275 * the flag is not created.
277 * - blkcg: blk-throttle becomes properly hierarchical.
279 CGRP_ROOT_SANE_BEHAVIOR = (1 << 0),
281 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
282 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
284 /* mount options live below bit 16 */
285 CGRP_ROOT_OPTION_MASK = (1 << 16) - 1,
287 CGRP_ROOT_SUBSYS_BOUND = (1 << 16), /* subsystems finished binding */
291 * A cgroupfs_root represents the root of a cgroup hierarchy, and may be
292 * associated with a superblock to form an active hierarchy. This is
293 * internal to cgroup core. Don't access directly from controllers.
295 struct cgroupfs_root {
296 struct super_block *sb;
298 /* The bitmask of subsystems attached to this hierarchy */
299 unsigned long subsys_mask;
301 /* Unique id for this hierarchy. */
304 /* The root cgroup for this hierarchy */
305 struct cgroup top_cgroup;
307 /* Tracks how many cgroups are currently defined in hierarchy.*/
308 int number_of_cgroups;
310 /* A list running through the active hierarchies */
311 struct list_head root_list;
313 /* Hierarchy-specific flags */
316 /* IDs for cgroups in this hierarchy */
317 struct idr cgroup_idr;
319 /* The path to use for release notifications. */
320 char release_agent_path[PATH_MAX];
322 /* The name for this hierarchy - may be empty */
323 char name[MAX_CGROUP_ROOT_NAMELEN];
327 * A css_set is a structure holding pointers to a set of
328 * cgroup_subsys_state objects. This saves space in the task struct
329 * object and speeds up fork()/exit(), since a single inc/dec and a
330 * list_add()/del() can bump the reference count on the entire cgroup
336 /* Reference count */
340 * List running through all cgroup groups in the same hash
341 * slot. Protected by css_set_lock
343 struct hlist_node hlist;
346 * List running through all tasks using this cgroup
347 * group. Protected by css_set_lock
349 struct list_head tasks;
352 * List of cgrp_cset_links pointing at cgroups referenced from this
353 * css_set. Protected by css_set_lock.
355 struct list_head cgrp_links;
358 * Set of subsystem states, one for each subsystem. This array is
359 * immutable after creation apart from the init_css_set during
360 * subsystem registration (at boot time).
362 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
364 /* For RCU-protected deletion */
365 struct rcu_head rcu_head;
369 * struct cftype: handler definitions for cgroup control files
371 * When reading/writing to a file:
372 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata
373 * - the 'cftype' of the file is file->f_dentry->d_fsdata
378 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
379 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
380 CFTYPE_INSANE = (1 << 2), /* don't create if sane_behavior */
381 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
384 #define MAX_CFTYPE_NAME 64
388 * By convention, the name should begin with the name of the
389 * subsystem, followed by a period. Zero length string indicates
390 * end of cftype array.
392 char name[MAX_CFTYPE_NAME];
395 * If not 0, file mode is set to this value, otherwise it will
396 * be figured out automatically
401 * If non-zero, defines the maximum length of string that can
402 * be passed to write_string; defaults to 64
404 size_t max_write_len;
410 * The subsys this file belongs to. Initialized automatically
411 * during registration. NULL for cgroup core files.
413 struct cgroup_subsys *ss;
416 * read_u64() is a shortcut for the common case of returning a
417 * single integer. Use it in place of read()
419 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
421 * read_s64() is a signed version of read_u64()
423 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
425 /* generic seq_file read interface */
426 int (*seq_show)(struct seq_file *sf, void *v);
428 /* optional ops, implement all or none */
429 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
430 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
431 void (*seq_stop)(struct seq_file *sf, void *v);
434 * write_u64() is a shortcut for the common case of accepting
435 * a single integer (as parsed by simple_strtoull) from
436 * userspace. Use in place of write(); return 0 or error.
438 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
441 * write_s64() is a signed version of write_u64()
443 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
447 * write_string() is passed a nul-terminated kernelspace
448 * buffer of maximum length determined by max_write_len.
449 * Returns 0 or -ve error code.
451 int (*write_string)(struct cgroup_subsys_state *css, struct cftype *cft,
454 * trigger() callback can be used to get some kick from the
455 * userspace, when the actual string written is not important
456 * at all. The private field can be used to determine the
457 * kick type for multiplexing.
459 int (*trigger)(struct cgroup_subsys_state *css, unsigned int event);
463 * cftype_sets describe cftypes belonging to a subsystem and are chained at
464 * cgroup_subsys->cftsets. Each cftset points to an array of cftypes
465 * terminated by zero length name.
468 struct list_head node; /* chained at subsys->cftsets */
473 * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. Don't
477 struct list_head node;
478 struct dentry *dentry;
480 struct cgroup_subsys_state *css;
483 struct simple_xattrs xattrs;
486 /* seq_file->private points to the following, only ->priv is public */
487 struct cgroup_open_file {
493 * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This
494 * function can be called as long as @cgrp is accessible.
496 static inline bool cgroup_sane_behavior(const struct cgroup *cgrp)
498 return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR;
501 /* Caller should hold rcu_read_lock() */
502 static inline const char *cgroup_name(const struct cgroup *cgrp)
504 return rcu_dereference(cgrp->name)->name;
507 static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
509 struct cgroup_open_file *of = seq->private;
513 static inline struct cftype *seq_cft(struct seq_file *seq)
515 struct cgroup_open_file *of = seq->private;
516 return of->cfe->type;
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);
524 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
525 int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
527 int cgroup_task_count(const struct cgroup *cgrp);
530 * Control Group taskset, used to pass around set of tasks to cgroup_subsys
533 struct cgroup_taskset;
534 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
535 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
536 struct cgroup_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset,
538 int cgroup_taskset_size(struct cgroup_taskset *tset);
541 * cgroup_taskset_for_each - iterate cgroup_taskset
542 * @task: the loop cursor
543 * @skip_css: skip if task's css matches this, %NULL to iterate through all
544 * @tset: taskset to iterate
546 #define cgroup_taskset_for_each(task, skip_css, tset) \
547 for ((task) = cgroup_taskset_first((tset)); (task); \
548 (task) = cgroup_taskset_next((tset))) \
550 cgroup_taskset_cur_css((tset), \
551 (skip_css)->ss->id) != (skip_css))
554 * Control Group subsystem type.
555 * See Documentation/cgroups/cgroups.txt for details
558 struct cgroup_subsys {
559 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
560 int (*css_online)(struct cgroup_subsys_state *css);
561 void (*css_offline)(struct cgroup_subsys_state *css);
562 void (*css_free)(struct cgroup_subsys_state *css);
564 int (*can_attach)(struct cgroup_subsys_state *css,
565 struct cgroup_taskset *tset);
566 void (*cancel_attach)(struct cgroup_subsys_state *css,
567 struct cgroup_taskset *tset);
568 void (*attach)(struct cgroup_subsys_state *css,
569 struct cgroup_taskset *tset);
570 void (*fork)(struct task_struct *task);
571 void (*exit)(struct cgroup_subsys_state *css,
572 struct cgroup_subsys_state *old_css,
573 struct task_struct *task);
574 void (*bind)(struct cgroup_subsys_state *root_css);
580 * If %false, this subsystem is properly hierarchical -
581 * configuration, resource accounting and restriction on a parent
582 * cgroup cover those of its children. If %true, hierarchy support
583 * is broken in some ways - some subsystems ignore hierarchy
584 * completely while others are only implemented half-way.
586 * It's now disallowed to create nested cgroups if the subsystem is
587 * broken and cgroup core will emit a warning message on such
588 * cases. Eventually, all subsystems will be made properly
589 * hierarchical and this will go away.
591 bool broken_hierarchy;
592 bool warned_broken_hierarchy;
594 /* the following two fields are initialized automtically during boot */
596 #define MAX_CGROUP_TYPE_NAMELEN 32
599 /* link to parent, protected by cgroup_lock() */
600 struct cgroupfs_root *root;
602 /* list of cftype_sets */
603 struct list_head cftsets;
605 /* base cftypes, automatically [de]registered with subsys itself */
606 struct cftype *base_cftypes;
607 struct cftype_set base_cftset;
610 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
611 #include <linux/cgroup_subsys.h>
615 * css_parent - find the parent css
616 * @css: the target cgroup_subsys_state
618 * Return the parent css of @css. This function is guaranteed to return
619 * non-NULL parent as long as @css isn't the root.
622 struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css)
628 * task_css_set_check - obtain a task's css_set with extra access conditions
629 * @task: the task to obtain css_set for
630 * @__c: extra condition expression to be passed to rcu_dereference_check()
632 * A task's css_set is RCU protected, initialized and exited while holding
633 * task_lock(), and can only be modified while holding both cgroup_mutex
634 * and task_lock() while the task is alive. This macro verifies that the
635 * caller is inside proper critical section and returns @task's css_set.
637 * The caller can also specify additional allowed conditions via @__c, such
638 * as locks used during the cgroup_subsys::attach() methods.
640 #ifdef CONFIG_PROVE_RCU
641 extern struct mutex cgroup_mutex;
642 #define task_css_set_check(task, __c) \
643 rcu_dereference_check((task)->cgroups, \
644 lockdep_is_held(&(task)->alloc_lock) || \
645 lockdep_is_held(&cgroup_mutex) || (__c))
647 #define task_css_set_check(task, __c) \
648 rcu_dereference((task)->cgroups)
652 * task_css_check - obtain css for (task, subsys) w/ extra access conds
653 * @task: the target task
654 * @subsys_id: the target subsystem ID
655 * @__c: extra condition expression to be passed to rcu_dereference_check()
657 * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The
658 * synchronization rules are the same as task_css_set_check().
660 #define task_css_check(task, subsys_id, __c) \
661 task_css_set_check((task), (__c))->subsys[(subsys_id)]
664 * task_css_set - obtain a task's css_set
665 * @task: the task to obtain css_set for
667 * See task_css_set_check().
669 static inline struct css_set *task_css_set(struct task_struct *task)
671 return task_css_set_check(task, false);
675 * task_css - obtain css for (task, subsys)
676 * @task: the target task
677 * @subsys_id: the target subsystem ID
679 * See task_css_check().
681 static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
684 return task_css_check(task, subsys_id, false);
687 static inline struct cgroup *task_cgroup(struct task_struct *task,
690 return task_css(task, subsys_id)->cgroup;
693 struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
694 struct cgroup_subsys_state *parent);
696 struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
699 * css_for_each_child - iterate through children of a css
700 * @pos: the css * to use as the loop cursor
701 * @parent: css whose children to walk
703 * Walk @parent's children. Must be called under rcu_read_lock(). A child
704 * css which hasn't finished ->css_online() or already has finished
705 * ->css_offline() may show up during traversal and it's each subsystem's
706 * responsibility to verify that each @pos is alive.
708 * If a subsystem synchronizes against the parent in its ->css_online() and
709 * before starting iterating, a css which finished ->css_online() is
710 * guaranteed to be visible in the future iterations.
712 * It is allowed to temporarily drop RCU read lock during iteration. The
713 * caller is responsible for ensuring that @pos remains accessible until
714 * the start of the next iteration by, for example, bumping the css refcnt.
716 #define css_for_each_child(pos, parent) \
717 for ((pos) = css_next_child(NULL, (parent)); (pos); \
718 (pos) = css_next_child((pos), (parent)))
720 struct cgroup_subsys_state *
721 css_next_descendant_pre(struct cgroup_subsys_state *pos,
722 struct cgroup_subsys_state *css);
724 struct cgroup_subsys_state *
725 css_rightmost_descendant(struct cgroup_subsys_state *pos);
728 * css_for_each_descendant_pre - pre-order walk of a css's descendants
729 * @pos: the css * to use as the loop cursor
730 * @root: css whose descendants to walk
732 * Walk @root's descendants. @root is included in the iteration and the
733 * first node to be visited. Must be called under rcu_read_lock(). A
734 * descendant css which hasn't finished ->css_online() or already has
735 * finished ->css_offline() may show up during traversal and it's each
736 * subsystem's responsibility to verify that each @pos is alive.
738 * If a subsystem synchronizes against the parent in its ->css_online() and
739 * before starting iterating, and synchronizes against @pos on each
740 * iteration, any descendant css which finished ->css_online() is
741 * guaranteed to be visible in the future iterations.
743 * In other words, the following guarantees that a descendant can't escape
744 * state updates of its ancestors.
748 * Lock @css's parent and @css;
749 * Inherit state from the parent;
753 * my_update_state(@css)
755 * css_for_each_descendant_pre(@pos, @css) {
758 * Update @css's state;
760 * Verify @pos is alive and inherit state from its parent;
765 * As long as the inheriting step, including checking the parent state, is
766 * enclosed inside @pos locking, double-locking the parent isn't necessary
767 * while inheriting. The state update to the parent is guaranteed to be
768 * visible by walking order and, as long as inheriting operations to the
769 * same @pos are atomic to each other, multiple updates racing each other
770 * still result in the correct state. It's guaranateed that at least one
771 * inheritance happens for any css after the latest update to its parent.
773 * If checking parent's state requires locking the parent, each inheriting
774 * iteration should lock and unlock both @pos->parent and @pos.
776 * Alternatively, a subsystem may choose to use a single global lock to
777 * synchronize ->css_online() and ->css_offline() against tree-walking
780 * It is allowed to temporarily drop RCU read lock during iteration. The
781 * caller is responsible for ensuring that @pos remains accessible until
782 * the start of the next iteration by, for example, bumping the css refcnt.
784 #define css_for_each_descendant_pre(pos, css) \
785 for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \
786 (pos) = css_next_descendant_pre((pos), (css)))
788 struct cgroup_subsys_state *
789 css_next_descendant_post(struct cgroup_subsys_state *pos,
790 struct cgroup_subsys_state *css);
793 * css_for_each_descendant_post - post-order walk of a css's descendants
794 * @pos: the css * to use as the loop cursor
795 * @css: css whose descendants to walk
797 * Similar to css_for_each_descendant_pre() but performs post-order
798 * traversal instead. @root is included in the iteration and the last
799 * node to be visited. Note that the walk visibility guarantee described
800 * in pre-order walk doesn't apply the same to post-order walks.
802 #define css_for_each_descendant_post(pos, css) \
803 for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
804 (pos) = css_next_descendant_post((pos), (css)))
806 /* A css_task_iter should be treated as an opaque object */
807 struct css_task_iter {
808 struct cgroup_subsys_state *origin_css;
809 struct list_head *cset_link;
810 struct list_head *task;
813 void css_task_iter_start(struct cgroup_subsys_state *css,
814 struct css_task_iter *it);
815 struct task_struct *css_task_iter_next(struct css_task_iter *it);
816 void css_task_iter_end(struct css_task_iter *it);
818 int css_scan_tasks(struct cgroup_subsys_state *css,
819 bool (*test)(struct task_struct *, void *),
820 void (*process)(struct task_struct *, void *),
821 void *data, struct ptr_heap *heap);
823 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
824 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
826 struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,
827 struct cgroup_subsys *ss);
829 #else /* !CONFIG_CGROUPS */
831 static inline int cgroup_init_early(void) { return 0; }
832 static inline int cgroup_init(void) { return 0; }
833 static inline void cgroup_fork(struct task_struct *p) {}
834 static inline void cgroup_post_fork(struct task_struct *p) {}
835 static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
837 static inline int cgroupstats_build(struct cgroupstats *stats,
838 struct dentry *dentry)
843 /* No cgroups - nothing to do */
844 static inline int cgroup_attach_task_all(struct task_struct *from,
845 struct task_struct *t)
850 #endif /* !CONFIG_CGROUPS */
852 #endif /* _LINUX_CGROUP_H */