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 */
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 #ifdef CONFIG_CGROUPS
25 struct cgroupfs_root;
26 struct cgroup_subsys;
27 struct inode;
28 struct cgroup;
29 struct css_id;
31 extern int cgroup_init_early(void);
32 extern int cgroup_init(void);
33 extern void cgroup_lock(void);
34 extern int cgroup_lock_is_held(void);
35 extern bool cgroup_lock_live_group(struct cgroup *cgrp);
36 extern void cgroup_unlock(void);
37 extern void cgroup_fork(struct task_struct *p);
38 extern void cgroup_post_fork(struct task_struct *p);
39 extern void cgroup_exit(struct task_struct *p, int run_callbacks);
40 extern int cgroupstats_build(struct cgroupstats *stats,
41 struct dentry *dentry);
42 extern int cgroup_load_subsys(struct cgroup_subsys *ss);
43 extern void cgroup_unload_subsys(struct cgroup_subsys *ss);
45 extern const struct file_operations proc_cgroup_operations;
47 /* Define the enumeration of all builtin cgroup subsystems */
48 #define SUBSYS(_x) _x ## _subsys_id,
49 #define IS_SUBSYS_ENABLED(option) IS_ENABLED(option)
50 enum cgroup_subsys_id {
51 #include <linux/cgroup_subsys.h>
52 CGROUP_SUBSYS_COUNT,
53 };
54 #undef IS_SUBSYS_ENABLED
55 #undef SUBSYS
57 /* Per-subsystem/per-cgroup state maintained by the system. */
58 struct cgroup_subsys_state {
59 /*
60 * The cgroup that this subsystem is attached to. Useful
61 * for subsystems that want to know about the cgroup
62 * hierarchy structure
63 */
64 struct cgroup *cgroup;
66 /*
67 * State maintained by the cgroup system to allow subsystems
68 * to be "busy". Should be accessed via css_get(),
69 * css_tryget() and css_put().
70 */
72 atomic_t refcnt;
74 unsigned long flags;
75 /* ID for this css, if possible */
76 struct css_id __rcu *id;
78 /* Used to put @cgroup->dentry on the last css_put() */
79 struct work_struct dput_work;
80 };
82 /* bits in struct cgroup_subsys_state flags field */
83 enum {
84 CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */
85 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
86 };
88 /* Caller must verify that the css is not for root cgroup */
89 static inline void __css_get(struct cgroup_subsys_state *css, int count)
90 {
91 atomic_add(count, &css->refcnt);
92 }
94 /*
95 * Call css_get() to hold a reference on the css; it can be used
96 * for a reference obtained via:
97 * - an existing ref-counted reference to the css
98 * - task->cgroups for a locked task
99 */
101 static inline void css_get(struct cgroup_subsys_state *css)
102 {
103 /* We don't need to reference count the root state */
104 if (!(css->flags & CSS_ROOT))
105 __css_get(css, 1);
106 }
108 /*
109 * Call css_tryget() to take a reference on a css if your existing
110 * (known-valid) reference isn't already ref-counted. Returns false if
111 * the css has been destroyed.
112 */
114 extern bool __css_tryget(struct cgroup_subsys_state *css);
115 static inline bool css_tryget(struct cgroup_subsys_state *css)
116 {
117 if (css->flags & CSS_ROOT)
118 return true;
119 return __css_tryget(css);
120 }
122 /*
123 * css_put() should be called to release a reference taken by
124 * css_get() or css_tryget()
125 */
127 extern void __css_put(struct cgroup_subsys_state *css);
128 static inline void css_put(struct cgroup_subsys_state *css)
129 {
130 if (!(css->flags & CSS_ROOT))
131 __css_put(css);
132 }
134 /* bits in struct cgroup flags field */
135 enum {
136 /* Control Group is dead */
137 CGRP_REMOVED,
138 /*
139 * Control Group has previously had a child cgroup or a task,
140 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
141 */
142 CGRP_RELEASABLE,
143 /* Control Group requires release notifications to userspace */
144 CGRP_NOTIFY_ON_RELEASE,
145 /*
146 * Clone the parent's configuration when creating a new child
147 * cpuset cgroup. For historical reasons, this option can be
148 * specified at mount time and thus is implemented here.
149 */
150 CGRP_CPUSET_CLONE_CHILDREN,
151 };
153 struct cgroup {
154 unsigned long flags; /* "unsigned long" so bitops work */
156 /*
157 * count users of this cgroup. >0 means busy, but doesn't
158 * necessarily indicate the number of tasks in the cgroup
159 */
160 atomic_t count;
162 int id; /* ida allocated in-hierarchy ID */
164 /*
165 * We link our 'sibling' struct into our parent's 'children'.
166 * Our children link their 'sibling' into our 'children'.
167 */
168 struct list_head sibling; /* my parent's children */
169 struct list_head children; /* my children */
170 struct list_head files; /* my files */
172 struct cgroup *parent; /* my parent */
173 struct dentry *dentry; /* cgroup fs entry, RCU protected */
175 /* Private pointers for each registered subsystem */
176 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
178 struct cgroupfs_root *root;
179 struct cgroup *top_cgroup;
181 /*
182 * List of cg_cgroup_links pointing at css_sets with
183 * tasks in this cgroup. Protected by css_set_lock
184 */
185 struct list_head css_sets;
187 struct list_head allcg_node; /* cgroupfs_root->allcg_list */
188 struct list_head cft_q_node; /* used during cftype add/rm */
190 /*
191 * Linked list running through all cgroups that can
192 * potentially be reaped by the release agent. Protected by
193 * release_list_lock
194 */
195 struct list_head release_list;
197 /*
198 * list of pidlists, up to two for each namespace (one for procs, one
199 * for tasks); created on demand.
200 */
201 struct list_head pidlists;
202 struct mutex pidlist_mutex;
204 /* For RCU-protected deletion */
205 struct rcu_head rcu_head;
207 /* List of events which userspace want to receive */
208 struct list_head event_list;
209 spinlock_t event_list_lock;
211 /* directory xattrs */
212 struct simple_xattrs xattrs;
213 };
215 /*
216 * A css_set is a structure holding pointers to a set of
217 * cgroup_subsys_state objects. This saves space in the task struct
218 * object and speeds up fork()/exit(), since a single inc/dec and a
219 * list_add()/del() can bump the reference count on the entire cgroup
220 * set for a task.
221 */
223 struct css_set {
225 /* Reference count */
226 atomic_t refcount;
228 /*
229 * List running through all cgroup groups in the same hash
230 * slot. Protected by css_set_lock
231 */
232 struct hlist_node hlist;
234 /*
235 * List running through all tasks using this cgroup
236 * group. Protected by css_set_lock
237 */
238 struct list_head tasks;
240 /*
241 * List of cg_cgroup_link objects on link chains from
242 * cgroups referenced from this css_set. Protected by
243 * css_set_lock
244 */
245 struct list_head cg_links;
247 /*
248 * Set of subsystem states, one for each subsystem. This array
249 * is immutable after creation apart from the init_css_set
250 * during subsystem registration (at boot time) and modular subsystem
251 * loading/unloading.
252 */
253 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
255 /* For RCU-protected deletion */
256 struct rcu_head rcu_head;
257 };
259 /*
260 * cgroup_map_cb is an abstract callback API for reporting map-valued
261 * control files
262 */
264 struct cgroup_map_cb {
265 int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value);
266 void *state;
267 };
269 /*
270 * struct cftype: handler definitions for cgroup control files
271 *
272 * When reading/writing to a file:
273 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata
274 * - the 'cftype' of the file is file->f_dentry->d_fsdata
275 */
277 /* cftype->flags */
278 #define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */
279 #define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create on root cg */
281 #define MAX_CFTYPE_NAME 64
283 struct cftype {
284 /*
285 * By convention, the name should begin with the name of the
286 * subsystem, followed by a period. Zero length string indicates
287 * end of cftype array.
288 */
289 char name[MAX_CFTYPE_NAME];
290 int private;
291 /*
292 * If not 0, file mode is set to this value, otherwise it will
293 * be figured out automatically
294 */
295 umode_t mode;
297 /*
298 * If non-zero, defines the maximum length of string that can
299 * be passed to write_string; defaults to 64
300 */
301 size_t max_write_len;
303 /* CFTYPE_* flags */
304 unsigned int flags;
306 int (*open)(struct inode *inode, struct file *file);
307 ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
308 struct file *file,
309 char __user *buf, size_t nbytes, loff_t *ppos);
310 /*
311 * read_u64() is a shortcut for the common case of returning a
312 * single integer. Use it in place of read()
313 */
314 u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft);
315 /*
316 * read_s64() is a signed version of read_u64()
317 */
318 s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft);
319 /*
320 * read_map() is used for defining a map of key/value
321 * pairs. It should call cb->fill(cb, key, value) for each
322 * entry. The key/value pairs (and their ordering) should not
323 * change between reboots.
324 */
325 int (*read_map)(struct cgroup *cont, struct cftype *cft,
326 struct cgroup_map_cb *cb);
327 /*
328 * read_seq_string() is used for outputting a simple sequence
329 * using seqfile.
330 */
331 int (*read_seq_string)(struct cgroup *cont, struct cftype *cft,
332 struct seq_file *m);
334 ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft,
335 struct file *file,
336 const char __user *buf, size_t nbytes, loff_t *ppos);
338 /*
339 * write_u64() is a shortcut for the common case of accepting
340 * a single integer (as parsed by simple_strtoull) from
341 * userspace. Use in place of write(); return 0 or error.
342 */
343 int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val);
344 /*
345 * write_s64() is a signed version of write_u64()
346 */
347 int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val);
349 /*
350 * write_string() is passed a nul-terminated kernelspace
351 * buffer of maximum length determined by max_write_len.
352 * Returns 0 or -ve error code.
353 */
354 int (*write_string)(struct cgroup *cgrp, struct cftype *cft,
355 const char *buffer);
356 /*
357 * trigger() callback can be used to get some kick from the
358 * userspace, when the actual string written is not important
359 * at all. The private field can be used to determine the
360 * kick type for multiplexing.
361 */
362 int (*trigger)(struct cgroup *cgrp, unsigned int event);
364 int (*release)(struct inode *inode, struct file *file);
366 /*
367 * register_event() callback will be used to add new userspace
368 * waiter for changes related to the cftype. Implement it if
369 * you want to provide this functionality. Use eventfd_signal()
370 * on eventfd to send notification to userspace.
371 */
372 int (*register_event)(struct cgroup *cgrp, struct cftype *cft,
373 struct eventfd_ctx *eventfd, const char *args);
374 /*
375 * unregister_event() callback will be called when userspace
376 * closes the eventfd or on cgroup removing.
377 * This callback must be implemented, if you want provide
378 * notification functionality.
379 */
380 void (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
381 struct eventfd_ctx *eventfd);
382 };
384 /*
385 * cftype_sets describe cftypes belonging to a subsystem and are chained at
386 * cgroup_subsys->cftsets. Each cftset points to an array of cftypes
387 * terminated by zero length name.
388 */
389 struct cftype_set {
390 struct list_head node; /* chained at subsys->cftsets */
391 struct cftype *cfts;
392 };
394 struct cgroup_scanner {
395 struct cgroup *cg;
396 int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
397 void (*process_task)(struct task_struct *p,
398 struct cgroup_scanner *scan);
399 struct ptr_heap *heap;
400 void *data;
401 };
403 int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
404 int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
406 int cgroup_is_removed(const struct cgroup *cgrp);
408 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
410 int cgroup_task_count(const struct cgroup *cgrp);
412 /* Return true if cgrp is a descendant of the task's cgroup */
413 int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
415 /*
416 * Control Group taskset, used to pass around set of tasks to cgroup_subsys
417 * methods.
418 */
419 struct cgroup_taskset;
420 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
421 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
422 struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset);
423 int cgroup_taskset_size(struct cgroup_taskset *tset);
425 /**
426 * cgroup_taskset_for_each - iterate cgroup_taskset
427 * @task: the loop cursor
428 * @skip_cgrp: skip if task's cgroup matches this, %NULL to iterate through all
429 * @tset: taskset to iterate
430 */
431 #define cgroup_taskset_for_each(task, skip_cgrp, tset) \
432 for ((task) = cgroup_taskset_first((tset)); (task); \
433 (task) = cgroup_taskset_next((tset))) \
434 if (!(skip_cgrp) || \
435 cgroup_taskset_cur_cgroup((tset)) != (skip_cgrp))
437 /*
438 * Control Group subsystem type.
439 * See Documentation/cgroups/cgroups.txt for details
440 */
442 struct cgroup_subsys {
443 struct cgroup_subsys_state *(*css_alloc)(struct cgroup *cgrp);
444 int (*css_online)(struct cgroup *cgrp);
445 void (*css_offline)(struct cgroup *cgrp);
446 void (*css_free)(struct cgroup *cgrp);
448 int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
449 void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
450 void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
451 void (*fork)(struct task_struct *task);
452 void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp,
453 struct task_struct *task);
454 void (*bind)(struct cgroup *root);
456 int subsys_id;
457 int active;
458 int disabled;
459 int early_init;
460 /*
461 * True if this subsys uses ID. ID is not available before cgroup_init()
462 * (not available in early_init time.)
463 */
464 bool use_id;
466 /*
467 * If %false, this subsystem is properly hierarchical -
468 * configuration, resource accounting and restriction on a parent
469 * cgroup cover those of its children. If %true, hierarchy support
470 * is broken in some ways - some subsystems ignore hierarchy
471 * completely while others are only implemented half-way.
472 *
473 * It's now disallowed to create nested cgroups if the subsystem is
474 * broken and cgroup core will emit a warning message on such
475 * cases. Eventually, all subsystems will be made properly
476 * hierarchical and this will go away.
477 */
478 bool broken_hierarchy;
479 bool warned_broken_hierarchy;
481 #define MAX_CGROUP_TYPE_NAMELEN 32
482 const char *name;
484 /*
485 * Link to parent, and list entry in parent's children.
486 * Protected by cgroup_lock()
487 */
488 struct cgroupfs_root *root;
489 struct list_head sibling;
490 /* used when use_id == true */
491 struct idr idr;
492 spinlock_t id_lock;
494 /* list of cftype_sets */
495 struct list_head cftsets;
497 /* base cftypes, automatically [de]registered with subsys itself */
498 struct cftype *base_cftypes;
499 struct cftype_set base_cftset;
501 /* should be defined only by modular subsystems */
502 struct module *module;
503 };
505 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
506 #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
507 #include <linux/cgroup_subsys.h>
508 #undef IS_SUBSYS_ENABLED
509 #undef SUBSYS
511 static inline struct cgroup_subsys_state *cgroup_subsys_state(
512 struct cgroup *cgrp, int subsys_id)
513 {
514 return cgrp->subsys[subsys_id];
515 }
517 /*
518 * function to get the cgroup_subsys_state which allows for extra
519 * rcu_dereference_check() conditions, such as locks used during the
520 * cgroup_subsys::attach() methods.
521 */
522 #define task_subsys_state_check(task, subsys_id, __c) \
523 rcu_dereference_check(task->cgroups->subsys[subsys_id], \
524 lockdep_is_held(&task->alloc_lock) || \
525 cgroup_lock_is_held() || (__c))
527 static inline struct cgroup_subsys_state *
528 task_subsys_state(struct task_struct *task, int subsys_id)
529 {
530 return task_subsys_state_check(task, subsys_id, false);
531 }
533 static inline struct cgroup* task_cgroup(struct task_struct *task,
534 int subsys_id)
535 {
536 return task_subsys_state(task, subsys_id)->cgroup;
537 }
539 /**
540 * cgroup_for_each_child - iterate through children of a cgroup
541 * @pos: the cgroup * to use as the loop cursor
542 * @cgroup: cgroup whose children to walk
543 *
544 * Walk @cgroup's children. Must be called under rcu_read_lock(). A child
545 * cgroup which hasn't finished ->css_online() or already has finished
546 * ->css_offline() may show up during traversal and it's each subsystem's
547 * responsibility to verify that each @pos is alive.
548 *
549 * If a subsystem synchronizes against the parent in its ->css_online() and
550 * before starting iterating, a cgroup which finished ->css_online() is
551 * guaranteed to be visible in the future iterations.
552 */
553 #define cgroup_for_each_child(pos, cgroup) \
554 list_for_each_entry_rcu(pos, &(cgroup)->children, sibling)
556 struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
557 struct cgroup *cgroup);
559 /**
560 * cgroup_for_each_descendant_pre - pre-order walk of a cgroup's descendants
561 * @pos: the cgroup * to use as the loop cursor
562 * @cgroup: cgroup whose descendants to walk
563 *
564 * Walk @cgroup's descendants. Must be called under rcu_read_lock(). A
565 * descendant cgroup which hasn't finished ->css_online() or already has
566 * finished ->css_offline() may show up during traversal and it's each
567 * subsystem's responsibility to verify that each @pos is alive.
568 *
569 * If a subsystem synchronizes against the parent in its ->css_online() and
570 * before starting iterating, and synchronizes against @pos on each
571 * iteration, any descendant cgroup which finished ->css_offline() is
572 * guaranteed to be visible in the future iterations.
573 *
574 * In other words, the following guarantees that a descendant can't escape
575 * state updates of its ancestors.
576 *
577 * my_online(@cgrp)
578 * {
579 * Lock @cgrp->parent and @cgrp;
580 * Inherit state from @cgrp->parent;
581 * Unlock both.
582 * }
583 *
584 * my_update_state(@cgrp)
585 * {
586 * Lock @cgrp;
587 * Update @cgrp's state;
588 * Unlock @cgrp;
589 *
590 * cgroup_for_each_descendant_pre(@pos, @cgrp) {
591 * Lock @pos;
592 * Verify @pos is alive and inherit state from @pos->parent;
593 * Unlock @pos;
594 * }
595 * }
596 *
597 * As long as the inheriting step, including checking the parent state, is
598 * enclosed inside @pos locking, double-locking the parent isn't necessary
599 * while inheriting. The state update to the parent is guaranteed to be
600 * visible by walking order and, as long as inheriting operations to the
601 * same @pos are atomic to each other, multiple updates racing each other
602 * still result in the correct state. It's guaranateed that at least one
603 * inheritance happens for any cgroup after the latest update to its
604 * parent.
605 *
606 * If checking parent's state requires locking the parent, each inheriting
607 * iteration should lock and unlock both @pos->parent and @pos.
608 *
609 * Alternatively, a subsystem may choose to use a single global lock to
610 * synchronize ->css_online() and ->css_offline() against tree-walking
611 * operations.
612 */
613 #define cgroup_for_each_descendant_pre(pos, cgroup) \
614 for (pos = cgroup_next_descendant_pre(NULL, (cgroup)); (pos); \
615 pos = cgroup_next_descendant_pre((pos), (cgroup)))
617 struct cgroup *cgroup_next_descendant_post(struct cgroup *pos,
618 struct cgroup *cgroup);
620 /**
621 * cgroup_for_each_descendant_post - post-order walk of a cgroup's descendants
622 * @pos: the cgroup * to use as the loop cursor
623 * @cgroup: cgroup whose descendants to walk
624 *
625 * Similar to cgroup_for_each_descendant_pre() but performs post-order
626 * traversal instead. Note that the walk visibility guarantee described in
627 * pre-order walk doesn't apply the same to post-order walks.
628 */
629 #define cgroup_for_each_descendant_post(pos, cgroup) \
630 for (pos = cgroup_next_descendant_post(NULL, (cgroup)); (pos); \
631 pos = cgroup_next_descendant_post((pos), (cgroup)))
633 /* A cgroup_iter should be treated as an opaque object */
634 struct cgroup_iter {
635 struct list_head *cg_link;
636 struct list_head *task;
637 };
639 /*
640 * To iterate across the tasks in a cgroup:
641 *
642 * 1) call cgroup_iter_start to initialize an iterator
643 *
644 * 2) call cgroup_iter_next() to retrieve member tasks until it
645 * returns NULL or until you want to end the iteration
646 *
647 * 3) call cgroup_iter_end() to destroy the iterator.
648 *
649 * Or, call cgroup_scan_tasks() to iterate through every task in a
650 * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling
651 * the test_task() callback, but not while calling the process_task()
652 * callback.
653 */
654 void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
655 struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
656 struct cgroup_iter *it);
657 void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
658 int cgroup_scan_tasks(struct cgroup_scanner *scan);
659 int cgroup_attach_task(struct cgroup *, struct task_struct *);
660 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
662 /*
663 * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
664 * if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
665 * CSS ID is assigned at cgroup allocation (create) automatically
666 * and removed when subsys calls free_css_id() function. This is because
667 * the lifetime of cgroup_subsys_state is subsys's matter.
668 *
669 * Looking up and scanning function should be called under rcu_read_lock().
670 * Taking cgroup_mutex is not necessary for following calls.
671 * But the css returned by this routine can be "not populated yet" or "being
672 * destroyed". The caller should check css and cgroup's status.
673 */
675 /*
676 * Typically Called at ->destroy(), or somewhere the subsys frees
677 * cgroup_subsys_state.
678 */
679 void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css);
681 /* Find a cgroup_subsys_state which has given ID */
683 struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id);
685 /*
686 * Get a cgroup whose id is greater than or equal to id under tree of root.
687 * Returning a cgroup_subsys_state or NULL.
688 */
689 struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id,
690 struct cgroup_subsys_state *root, int *foundid);
692 /* Returns true if root is ancestor of cg */
693 bool css_is_ancestor(struct cgroup_subsys_state *cg,
694 const struct cgroup_subsys_state *root);
696 /* Get id and depth of css */
697 unsigned short css_id(struct cgroup_subsys_state *css);
698 unsigned short css_depth(struct cgroup_subsys_state *css);
699 struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id);
701 #else /* !CONFIG_CGROUPS */
703 static inline int cgroup_init_early(void) { return 0; }
704 static inline int cgroup_init(void) { return 0; }
705 static inline void cgroup_fork(struct task_struct *p) {}
706 static inline void cgroup_fork_callbacks(struct task_struct *p) {}
707 static inline void cgroup_post_fork(struct task_struct *p) {}
708 static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
710 static inline void cgroup_lock(void) {}
711 static inline void cgroup_unlock(void) {}
712 static inline int cgroupstats_build(struct cgroupstats *stats,
713 struct dentry *dentry)
714 {
715 return -EINVAL;
716 }
718 /* No cgroups - nothing to do */
719 static inline int cgroup_attach_task_all(struct task_struct *from,
720 struct task_struct *t)
721 {
722 return 0;
723 }
725 #endif /* !CONFIG_CGROUPS */
727 #endif /* _LINUX_CGROUP_H */