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/rculist.h>
15 #include <linux/cgroupstats.h>
17 #include <linux/seq_file.h>
18 #include <linux/kernfs.h>
19 #include <linux/jump_label.h>
21 #include <linux/cgroup-defs.h>
26 * All weight knobs on the default hierarhcy should use the following min,
27 * default and max values. The default value is the logarithmic center of
28 * MIN and MAX and allows 100x to be expressed in both directions.
30 #define CGROUP_WEIGHT_MIN 1
31 #define CGROUP_WEIGHT_DFL 100
32 #define CGROUP_WEIGHT_MAX 10000
34 /* a css_task_iter should be treated as an opaque object */
35 struct css_task_iter
{
36 struct cgroup_subsys
*ss
;
38 struct list_head
*cset_pos
;
39 struct list_head
*cset_head
;
41 struct list_head
*task_pos
;
42 struct list_head
*tasks_head
;
43 struct list_head
*mg_tasks_head
;
45 struct css_set
*cur_cset
;
46 struct task_struct
*cur_task
;
47 struct list_head iters_node
; /* css_set->task_iters */
50 extern struct cgroup_root cgrp_dfl_root
;
51 extern struct css_set init_css_set
;
53 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
54 #include <linux/cgroup_subsys.h>
58 extern struct static_key_true _x ## _cgrp_subsys_enabled_key; \
59 extern struct static_key_true _x ## _cgrp_subsys_on_dfl_key;
60 #include <linux/cgroup_subsys.h>
64 * cgroup_subsys_enabled - fast test on whether a subsys is enabled
65 * @ss: subsystem in question
67 #define cgroup_subsys_enabled(ss) \
68 static_branch_likely(&ss ## _enabled_key)
71 * cgroup_subsys_on_dfl - fast test on whether a subsys is on default hierarchy
72 * @ss: subsystem in question
74 #define cgroup_subsys_on_dfl(ss) \
75 static_branch_likely(&ss ## _on_dfl_key)
77 bool css_has_online_children(struct cgroup_subsys_state
*css
);
78 struct cgroup_subsys_state
*css_from_id(int id
, struct cgroup_subsys
*ss
);
79 struct cgroup_subsys_state
*cgroup_get_e_css(struct cgroup
*cgroup
,
80 struct cgroup_subsys
*ss
);
81 struct cgroup_subsys_state
*css_tryget_online_from_dir(struct dentry
*dentry
,
82 struct cgroup_subsys
*ss
);
84 bool cgroup_is_descendant(struct cgroup
*cgrp
, struct cgroup
*ancestor
);
85 int cgroup_attach_task_all(struct task_struct
*from
, struct task_struct
*);
86 int cgroup_transfer_tasks(struct cgroup
*to
, struct cgroup
*from
);
88 int cgroup_add_dfl_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
);
89 int cgroup_add_legacy_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
);
90 int cgroup_rm_cftypes(struct cftype
*cfts
);
92 char *task_cgroup_path(struct task_struct
*task
, char *buf
, size_t buflen
);
93 int cgroupstats_build(struct cgroupstats
*stats
, struct dentry
*dentry
);
94 int proc_cgroup_show(struct seq_file
*m
, struct pid_namespace
*ns
,
95 struct pid
*pid
, struct task_struct
*tsk
);
97 void cgroup_fork(struct task_struct
*p
);
98 extern int cgroup_can_fork(struct task_struct
*p
,
99 void *ss_priv
[CGROUP_CANFORK_COUNT
]);
100 extern void cgroup_cancel_fork(struct task_struct
*p
,
101 void *ss_priv
[CGROUP_CANFORK_COUNT
]);
102 extern void cgroup_post_fork(struct task_struct
*p
,
103 void *old_ss_priv
[CGROUP_CANFORK_COUNT
]);
104 void cgroup_exit(struct task_struct
*p
);
105 void cgroup_free(struct task_struct
*p
);
107 int cgroup_init_early(void);
108 int cgroup_init(void);
111 * Iteration helpers and macros.
114 struct cgroup_subsys_state
*css_next_child(struct cgroup_subsys_state
*pos
,
115 struct cgroup_subsys_state
*parent
);
116 struct cgroup_subsys_state
*css_next_descendant_pre(struct cgroup_subsys_state
*pos
,
117 struct cgroup_subsys_state
*css
);
118 struct cgroup_subsys_state
*css_rightmost_descendant(struct cgroup_subsys_state
*pos
);
119 struct cgroup_subsys_state
*css_next_descendant_post(struct cgroup_subsys_state
*pos
,
120 struct cgroup_subsys_state
*css
);
122 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
);
123 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
);
125 void css_task_iter_start(struct cgroup_subsys_state
*css
,
126 struct css_task_iter
*it
);
127 struct task_struct
*css_task_iter_next(struct css_task_iter
*it
);
128 void css_task_iter_end(struct css_task_iter
*it
);
131 * css_for_each_child - iterate through children of a css
132 * @pos: the css * to use as the loop cursor
133 * @parent: css whose children to walk
135 * Walk @parent's children. Must be called under rcu_read_lock().
137 * If a subsystem synchronizes ->css_online() and the start of iteration, a
138 * css which finished ->css_online() is guaranteed to be visible in the
139 * future iterations and will stay visible until the last reference is put.
140 * A css which hasn't finished ->css_online() or already finished
141 * ->css_offline() may show up during traversal. It's each subsystem's
142 * responsibility to synchronize against on/offlining.
144 * It is allowed to temporarily drop RCU read lock during iteration. The
145 * caller is responsible for ensuring that @pos remains accessible until
146 * the start of the next iteration by, for example, bumping the css refcnt.
148 #define css_for_each_child(pos, parent) \
149 for ((pos) = css_next_child(NULL, (parent)); (pos); \
150 (pos) = css_next_child((pos), (parent)))
153 * css_for_each_descendant_pre - pre-order walk of a css's descendants
154 * @pos: the css * to use as the loop cursor
155 * @root: css whose descendants to walk
157 * Walk @root's descendants. @root is included in the iteration and the
158 * first node to be visited. Must be called under rcu_read_lock().
160 * If a subsystem synchronizes ->css_online() and the start of iteration, a
161 * css which finished ->css_online() is guaranteed to be visible in the
162 * future iterations and will stay visible until the last reference is put.
163 * A css which hasn't finished ->css_online() or already finished
164 * ->css_offline() may show up during traversal. It's each subsystem's
165 * responsibility to synchronize against on/offlining.
167 * For example, the following guarantees that a descendant can't escape
168 * state updates of its ancestors.
172 * Lock @css's parent and @css;
173 * Inherit state from the parent;
177 * my_update_state(@css)
179 * css_for_each_descendant_pre(@pos, @css) {
182 * Update @css's state;
184 * Verify @pos is alive and inherit state from its parent;
189 * As long as the inheriting step, including checking the parent state, is
190 * enclosed inside @pos locking, double-locking the parent isn't necessary
191 * while inheriting. The state update to the parent is guaranteed to be
192 * visible by walking order and, as long as inheriting operations to the
193 * same @pos are atomic to each other, multiple updates racing each other
194 * still result in the correct state. It's guaranateed that at least one
195 * inheritance happens for any css after the latest update to its parent.
197 * If checking parent's state requires locking the parent, each inheriting
198 * iteration should lock and unlock both @pos->parent and @pos.
200 * Alternatively, a subsystem may choose to use a single global lock to
201 * synchronize ->css_online() and ->css_offline() against tree-walking
204 * It is allowed to temporarily drop RCU read lock during iteration. The
205 * caller is responsible for ensuring that @pos remains accessible until
206 * the start of the next iteration by, for example, bumping the css refcnt.
208 #define css_for_each_descendant_pre(pos, css) \
209 for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \
210 (pos) = css_next_descendant_pre((pos), (css)))
213 * css_for_each_descendant_post - post-order walk of a css's descendants
214 * @pos: the css * to use as the loop cursor
215 * @css: css whose descendants to walk
217 * Similar to css_for_each_descendant_pre() but performs post-order
218 * traversal instead. @root is included in the iteration and the last
219 * node to be visited.
221 * If a subsystem synchronizes ->css_online() and the start of iteration, a
222 * css which finished ->css_online() is guaranteed to be visible in the
223 * future iterations and will stay visible until the last reference is put.
224 * A css which hasn't finished ->css_online() or already finished
225 * ->css_offline() may show up during traversal. It's each subsystem's
226 * responsibility to synchronize against on/offlining.
228 * Note that the walk visibility guarantee example described in pre-order
229 * walk doesn't apply the same to post-order walks.
231 #define css_for_each_descendant_post(pos, css) \
232 for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
233 (pos) = css_next_descendant_post((pos), (css)))
236 * cgroup_taskset_for_each - iterate cgroup_taskset
237 * @task: the loop cursor
238 * @tset: taskset to iterate
240 * @tset may contain multiple tasks and they may belong to multiple
241 * processes. When there are multiple tasks in @tset, if a task of a
242 * process is in @tset, all tasks of the process are in @tset. Also, all
243 * are guaranteed to share the same source and destination csses.
245 * Iteration is not in any specific order.
247 #define cgroup_taskset_for_each(task, tset) \
248 for ((task) = cgroup_taskset_first((tset)); (task); \
249 (task) = cgroup_taskset_next((tset)))
252 * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset
253 * @leader: the loop cursor
254 * @tset: takset to iterate
256 * Iterate threadgroup leaders of @tset. For single-task migrations, @tset
257 * may not contain any.
259 #define cgroup_taskset_for_each_leader(leader, tset) \
260 for ((leader) = cgroup_taskset_first((tset)); (leader); \
261 (leader) = cgroup_taskset_next((tset))) \
262 if ((leader) != (leader)->group_leader) \
271 * css_get - obtain a reference on the specified css
274 * The caller must already have a reference.
276 static inline void css_get(struct cgroup_subsys_state
*css
)
278 if (!(css
->flags
& CSS_NO_REF
))
279 percpu_ref_get(&css
->refcnt
);
283 * css_get_many - obtain references on the specified css
285 * @n: number of references to get
287 * The caller must already have a reference.
289 static inline void css_get_many(struct cgroup_subsys_state
*css
, unsigned int n
)
291 if (!(css
->flags
& CSS_NO_REF
))
292 percpu_ref_get_many(&css
->refcnt
, n
);
296 * css_tryget - try to obtain a reference on the specified css
299 * Obtain a reference on @css unless it already has reached zero and is
300 * being released. This function doesn't care whether @css is on or
301 * offline. The caller naturally needs to ensure that @css is accessible
302 * but doesn't have to be holding a reference on it - IOW, RCU protected
303 * access is good enough for this function. Returns %true if a reference
304 * count was successfully obtained; %false otherwise.
306 static inline bool css_tryget(struct cgroup_subsys_state
*css
)
308 if (!(css
->flags
& CSS_NO_REF
))
309 return percpu_ref_tryget(&css
->refcnt
);
314 * css_tryget_online - try to obtain a reference on the specified css if online
317 * Obtain a reference on @css if it's online. The caller naturally needs
318 * to ensure that @css is accessible but doesn't have to be holding a
319 * reference on it - IOW, RCU protected access is good enough for this
320 * function. Returns %true if a reference count was successfully obtained;
323 static inline bool css_tryget_online(struct cgroup_subsys_state
*css
)
325 if (!(css
->flags
& CSS_NO_REF
))
326 return percpu_ref_tryget_live(&css
->refcnt
);
331 * css_put - put a css reference
334 * Put a reference obtained via css_get() and css_tryget_online().
336 static inline void css_put(struct cgroup_subsys_state
*css
)
338 if (!(css
->flags
& CSS_NO_REF
))
339 percpu_ref_put(&css
->refcnt
);
343 * css_put_many - put css references
345 * @n: number of references to put
347 * Put references obtained via css_get() and css_tryget_online().
349 static inline void css_put_many(struct cgroup_subsys_state
*css
, unsigned int n
)
351 if (!(css
->flags
& CSS_NO_REF
))
352 percpu_ref_put_many(&css
->refcnt
, n
);
356 * task_css_set_check - obtain a task's css_set with extra access conditions
357 * @task: the task to obtain css_set for
358 * @__c: extra condition expression to be passed to rcu_dereference_check()
360 * A task's css_set is RCU protected, initialized and exited while holding
361 * task_lock(), and can only be modified while holding both cgroup_mutex
362 * and task_lock() while the task is alive. This macro verifies that the
363 * caller is inside proper critical section and returns @task's css_set.
365 * The caller can also specify additional allowed conditions via @__c, such
366 * as locks used during the cgroup_subsys::attach() methods.
368 #ifdef CONFIG_PROVE_RCU
369 extern struct mutex cgroup_mutex
;
370 extern spinlock_t css_set_lock
;
371 #define task_css_set_check(task, __c) \
372 rcu_dereference_check((task)->cgroups, \
373 lockdep_is_held(&cgroup_mutex) || \
374 lockdep_is_held(&css_set_lock) || \
375 ((task)->flags & PF_EXITING) || (__c))
377 #define task_css_set_check(task, __c) \
378 rcu_dereference((task)->cgroups)
382 * task_css_check - obtain css for (task, subsys) w/ extra access conds
383 * @task: the target task
384 * @subsys_id: the target subsystem ID
385 * @__c: extra condition expression to be passed to rcu_dereference_check()
387 * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The
388 * synchronization rules are the same as task_css_set_check().
390 #define task_css_check(task, subsys_id, __c) \
391 task_css_set_check((task), (__c))->subsys[(subsys_id)]
394 * task_css_set - obtain a task's css_set
395 * @task: the task to obtain css_set for
397 * See task_css_set_check().
399 static inline struct css_set
*task_css_set(struct task_struct
*task
)
401 return task_css_set_check(task
, false);
405 * task_css - obtain css for (task, subsys)
406 * @task: the target task
407 * @subsys_id: the target subsystem ID
409 * See task_css_check().
411 static inline struct cgroup_subsys_state
*task_css(struct task_struct
*task
,
414 return task_css_check(task
, subsys_id
, false);
418 * task_get_css - find and get the css for (task, subsys)
419 * @task: the target task
420 * @subsys_id: the target subsystem ID
422 * Find the css for the (@task, @subsys_id) combination, increment a
423 * reference on and return it. This function is guaranteed to return a
426 static inline struct cgroup_subsys_state
*
427 task_get_css(struct task_struct
*task
, int subsys_id
)
429 struct cgroup_subsys_state
*css
;
433 css
= task_css(task
, subsys_id
);
434 if (likely(css_tryget_online(css
)))
443 * task_css_is_root - test whether a task belongs to the root css
444 * @task: the target task
445 * @subsys_id: the target subsystem ID
447 * Test whether @task belongs to the root css on the specified subsystem.
448 * May be invoked in any context.
450 static inline bool task_css_is_root(struct task_struct
*task
, int subsys_id
)
452 return task_css_check(task
, subsys_id
, true) ==
453 init_css_set
.subsys
[subsys_id
];
456 static inline struct cgroup
*task_cgroup(struct task_struct
*task
,
459 return task_css(task
, subsys_id
)->cgroup
;
462 /* no synchronization, the result can only be used as a hint */
463 static inline bool cgroup_is_populated(struct cgroup
*cgrp
)
465 return cgrp
->populated_cnt
;
468 /* returns ino associated with a cgroup */
469 static inline ino_t
cgroup_ino(struct cgroup
*cgrp
)
471 return cgrp
->kn
->ino
;
474 /* cft/css accessors for cftype->write() operation */
475 static inline struct cftype
*of_cft(struct kernfs_open_file
*of
)
480 struct cgroup_subsys_state
*of_css(struct kernfs_open_file
*of
);
482 /* cft/css accessors for cftype->seq_*() operations */
483 static inline struct cftype
*seq_cft(struct seq_file
*seq
)
485 return of_cft(seq
->private);
488 static inline struct cgroup_subsys_state
*seq_css(struct seq_file
*seq
)
490 return of_css(seq
->private);
494 * Name / path handling functions. All are thin wrappers around the kernfs
495 * counterparts and can be called under any context.
498 static inline int cgroup_name(struct cgroup
*cgrp
, char *buf
, size_t buflen
)
500 return kernfs_name(cgrp
->kn
, buf
, buflen
);
503 static inline char * __must_check
cgroup_path(struct cgroup
*cgrp
, char *buf
,
506 return kernfs_path(cgrp
->kn
, buf
, buflen
);
509 static inline void pr_cont_cgroup_name(struct cgroup
*cgrp
)
511 pr_cont_kernfs_name(cgrp
->kn
);
514 static inline void pr_cont_cgroup_path(struct cgroup
*cgrp
)
516 pr_cont_kernfs_path(cgrp
->kn
);
520 * cgroup_file_notify - generate a file modified event for a cgroup_file
521 * @cfile: target cgroup_file
523 * @cfile must have been obtained by setting cftype->file_offset.
525 static inline void cgroup_file_notify(struct cgroup_file
*cfile
)
527 /* might not have been created due to one of the CFTYPE selector flags */
529 kernfs_notify(cfile
->kn
);
532 #else /* !CONFIG_CGROUPS */
534 struct cgroup_subsys_state
;
536 static inline void css_put(struct cgroup_subsys_state
*css
) {}
537 static inline int cgroup_attach_task_all(struct task_struct
*from
,
538 struct task_struct
*t
) { return 0; }
539 static inline int cgroupstats_build(struct cgroupstats
*stats
,
540 struct dentry
*dentry
) { return -EINVAL
; }
542 static inline void cgroup_fork(struct task_struct
*p
) {}
543 static inline int cgroup_can_fork(struct task_struct
*p
,
544 void *ss_priv
[CGROUP_CANFORK_COUNT
])
546 static inline void cgroup_cancel_fork(struct task_struct
*p
,
547 void *ss_priv
[CGROUP_CANFORK_COUNT
]) {}
548 static inline void cgroup_post_fork(struct task_struct
*p
,
549 void *ss_priv
[CGROUP_CANFORK_COUNT
]) {}
550 static inline void cgroup_exit(struct task_struct
*p
) {}
551 static inline void cgroup_free(struct task_struct
*p
) {}
553 static inline int cgroup_init_early(void) { return 0; }
554 static inline int cgroup_init(void) { return 0; }
556 #endif /* !CONFIG_CGROUPS */
558 #endif /* _LINUX_CGROUP_H */