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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 | */ |
10 | |
11 | #include <linux/sched.h> |
12 | #include <linux/cpumask.h> |
13 | #include <linux/nodemask.h> |
14 | #include <linux/rcupdate.h> |
15 | #include <linux/cgroupstats.h> |
16 | #include <linux/prio_heap.h> |
17 | #include <linux/rwsem.h> |
18 | #include <linux/idr.h> |
19 | |
20 | #ifdef CONFIG_CGROUPS |
21 | |
22 | struct cgroupfs_root; |
23 | struct cgroup_subsys; |
24 | struct inode; |
25 | struct cgroup; |
26 | struct css_id; |
27 | |
28 | extern int cgroup_init_early(void); |
29 | extern int cgroup_init(void); |
30 | extern void cgroup_lock(void); |
31 | extern int cgroup_lock_is_held(void); |
32 | extern bool cgroup_lock_live_group(struct cgroup *cgrp); |
33 | extern void cgroup_unlock(void); |
34 | extern void cgroup_fork(struct task_struct *p); |
35 | extern void cgroup_fork_callbacks(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); |
40 | extern int cgroup_load_subsys(struct cgroup_subsys *ss); |
41 | extern void cgroup_unload_subsys(struct cgroup_subsys *ss); |
42 | |
43 | extern const struct file_operations proc_cgroup_operations; |
44 | |
45 | /* Define the enumeration of all builtin cgroup subsystems */ |
46 | #define SUBSYS(_x) _x ## _subsys_id, |
47 | enum cgroup_subsys_id { |
48 | #include <linux/cgroup_subsys.h> |
49 | CGROUP_BUILTIN_SUBSYS_COUNT |
50 | }; |
51 | #undef SUBSYS |
52 | /* |
53 | * This define indicates the maximum number of subsystems that can be loaded |
54 | * at once. We limit to this many since cgroupfs_root has subsys_bits to keep |
55 | * track of all of them. |
56 | */ |
57 | #define CGROUP_SUBSYS_COUNT (BITS_PER_BYTE*sizeof(unsigned long)) |
58 | |
59 | /* Per-subsystem/per-cgroup state maintained by the system. */ |
60 | struct cgroup_subsys_state { |
61 | /* |
62 | * The cgroup that this subsystem is attached to. Useful |
63 | * for subsystems that want to know about the cgroup |
64 | * hierarchy structure |
65 | */ |
66 | struct cgroup *cgroup; |
67 | |
68 | /* |
69 | * State maintained by the cgroup system to allow subsystems |
70 | * to be "busy". Should be accessed via css_get(), |
71 | * css_tryget() and and css_put(). |
72 | */ |
73 | |
74 | atomic_t refcnt; |
75 | |
76 | unsigned long flags; |
77 | /* ID for this css, if possible */ |
78 | struct css_id __rcu *id; |
79 | }; |
80 | |
81 | /* bits in struct cgroup_subsys_state flags field */ |
82 | enum { |
83 | CSS_ROOT, /* This CSS is the root of the subsystem */ |
84 | CSS_REMOVED, /* This CSS is dead */ |
85 | }; |
86 | |
87 | /* Caller must verify that the css is not for root cgroup */ |
88 | static inline void __css_get(struct cgroup_subsys_state *css, int count) |
89 | { |
90 | atomic_add(count, &css->refcnt); |
91 | } |
92 | |
93 | /* |
94 | * Call css_get() to hold a reference on the css; it can be used |
95 | * for a reference obtained via: |
96 | * - an existing ref-counted reference to the css |
97 | * - task->cgroups for a locked task |
98 | */ |
99 | |
100 | static inline void css_get(struct cgroup_subsys_state *css) |
101 | { |
102 | /* We don't need to reference count the root state */ |
103 | if (!test_bit(CSS_ROOT, &css->flags)) |
104 | __css_get(css, 1); |
105 | } |
106 | |
107 | static inline bool css_is_removed(struct cgroup_subsys_state *css) |
108 | { |
109 | return test_bit(CSS_REMOVED, &css->flags); |
110 | } |
111 | |
112 | /* |
113 | * Call css_tryget() to take a reference on a css if your existing |
114 | * (known-valid) reference isn't already ref-counted. Returns false if |
115 | * the css has been destroyed. |
116 | */ |
117 | |
118 | static inline bool css_tryget(struct cgroup_subsys_state *css) |
119 | { |
120 | if (test_bit(CSS_ROOT, &css->flags)) |
121 | return true; |
122 | while (!atomic_inc_not_zero(&css->refcnt)) { |
123 | if (test_bit(CSS_REMOVED, &css->flags)) |
124 | return false; |
125 | cpu_relax(); |
126 | } |
127 | return true; |
128 | } |
129 | |
130 | /* |
131 | * css_put() should be called to release a reference taken by |
132 | * css_get() or css_tryget() |
133 | */ |
134 | |
135 | extern void __css_put(struct cgroup_subsys_state *css, int count); |
136 | static inline void css_put(struct cgroup_subsys_state *css) |
137 | { |
138 | if (!test_bit(CSS_ROOT, &css->flags)) |
139 | __css_put(css, 1); |
140 | } |
141 | |
142 | /* bits in struct cgroup flags field */ |
143 | enum { |
144 | /* Control Group is dead */ |
145 | CGRP_REMOVED, |
146 | /* |
147 | * Control Group has previously had a child cgroup or a task, |
148 | * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) |
149 | */ |
150 | CGRP_RELEASABLE, |
151 | /* Control Group requires release notifications to userspace */ |
152 | CGRP_NOTIFY_ON_RELEASE, |
153 | /* |
154 | * A thread in rmdir() is wating for this cgroup. |
155 | */ |
156 | CGRP_WAIT_ON_RMDIR, |
157 | /* |
158 | * Clone cgroup values when creating a new child cgroup |
159 | */ |
160 | CGRP_CLONE_CHILDREN, |
161 | }; |
162 | |
163 | /* which pidlist file are we talking about? */ |
164 | enum cgroup_filetype { |
165 | CGROUP_FILE_PROCS, |
166 | CGROUP_FILE_TASKS, |
167 | }; |
168 | |
169 | /* |
170 | * A pidlist is a list of pids that virtually represents the contents of one |
171 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, |
172 | * a pair (one each for procs, tasks) for each pid namespace that's relevant |
173 | * to the cgroup. |
174 | */ |
175 | struct cgroup_pidlist { |
176 | /* |
177 | * used to find which pidlist is wanted. doesn't change as long as |
178 | * this particular list stays in the list. |
179 | */ |
180 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; |
181 | /* array of xids */ |
182 | pid_t *list; |
183 | /* how many elements the above list has */ |
184 | int length; |
185 | /* how many files are using the current array */ |
186 | int use_count; |
187 | /* each of these stored in a list by its cgroup */ |
188 | struct list_head links; |
189 | /* pointer to the cgroup we belong to, for list removal purposes */ |
190 | struct cgroup *owner; |
191 | /* protects the other fields */ |
192 | struct rw_semaphore mutex; |
193 | }; |
194 | |
195 | struct cgroup { |
196 | unsigned long flags; /* "unsigned long" so bitops work */ |
197 | |
198 | /* |
199 | * count users of this cgroup. >0 means busy, but doesn't |
200 | * necessarily indicate the number of tasks in the cgroup |
201 | */ |
202 | atomic_t count; |
203 | |
204 | /* |
205 | * We link our 'sibling' struct into our parent's 'children'. |
206 | * Our children link their 'sibling' into our 'children'. |
207 | */ |
208 | struct list_head sibling; /* my parent's children */ |
209 | struct list_head children; /* my children */ |
210 | |
211 | struct cgroup *parent; /* my parent */ |
212 | struct dentry __rcu *dentry; /* cgroup fs entry, RCU protected */ |
213 | |
214 | /* Private pointers for each registered subsystem */ |
215 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
216 | |
217 | struct cgroupfs_root *root; |
218 | struct cgroup *top_cgroup; |
219 | |
220 | /* |
221 | * List of cg_cgroup_links pointing at css_sets with |
222 | * tasks in this cgroup. Protected by css_set_lock |
223 | */ |
224 | struct list_head css_sets; |
225 | |
226 | /* |
227 | * Linked list running through all cgroups that can |
228 | * potentially be reaped by the release agent. Protected by |
229 | * release_list_lock |
230 | */ |
231 | struct list_head release_list; |
232 | |
233 | /* |
234 | * list of pidlists, up to two for each namespace (one for procs, one |
235 | * for tasks); created on demand. |
236 | */ |
237 | struct list_head pidlists; |
238 | struct mutex pidlist_mutex; |
239 | |
240 | /* For RCU-protected deletion */ |
241 | struct rcu_head rcu_head; |
242 | |
243 | /* List of events which userspace want to receive */ |
244 | struct list_head event_list; |
245 | spinlock_t event_list_lock; |
246 | }; |
247 | |
248 | /* |
249 | * A css_set is a structure holding pointers to a set of |
250 | * cgroup_subsys_state objects. This saves space in the task struct |
251 | * object and speeds up fork()/exit(), since a single inc/dec and a |
252 | * list_add()/del() can bump the reference count on the entire cgroup |
253 | * set for a task. |
254 | */ |
255 | |
256 | struct css_set { |
257 | |
258 | /* Reference count */ |
259 | atomic_t refcount; |
260 | |
261 | /* |
262 | * List running through all cgroup groups in the same hash |
263 | * slot. Protected by css_set_lock |
264 | */ |
265 | struct hlist_node hlist; |
266 | |
267 | /* |
268 | * List running through all tasks using this cgroup |
269 | * group. Protected by css_set_lock |
270 | */ |
271 | struct list_head tasks; |
272 | |
273 | /* |
274 | * List of cg_cgroup_link objects on link chains from |
275 | * cgroups referenced from this css_set. Protected by |
276 | * css_set_lock |
277 | */ |
278 | struct list_head cg_links; |
279 | |
280 | /* |
281 | * Set of subsystem states, one for each subsystem. This array |
282 | * is immutable after creation apart from the init_css_set |
283 | * during subsystem registration (at boot time) and modular subsystem |
284 | * loading/unloading. |
285 | */ |
286 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
287 | |
288 | /* For RCU-protected deletion */ |
289 | struct rcu_head rcu_head; |
290 | }; |
291 | |
292 | /* |
293 | * cgroup_map_cb is an abstract callback API for reporting map-valued |
294 | * control files |
295 | */ |
296 | |
297 | struct cgroup_map_cb { |
298 | int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); |
299 | void *state; |
300 | }; |
301 | |
302 | /* |
303 | * struct cftype: handler definitions for cgroup control files |
304 | * |
305 | * When reading/writing to a file: |
306 | * - the cgroup to use is file->f_dentry->d_parent->d_fsdata |
307 | * - the 'cftype' of the file is file->f_dentry->d_fsdata |
308 | */ |
309 | |
310 | #define MAX_CFTYPE_NAME 64 |
311 | struct cftype { |
312 | /* |
313 | * By convention, the name should begin with the name of the |
314 | * subsystem, followed by a period |
315 | */ |
316 | char name[MAX_CFTYPE_NAME]; |
317 | int private; |
318 | /* |
319 | * If not 0, file mode is set to this value, otherwise it will |
320 | * be figured out automatically |
321 | */ |
322 | mode_t mode; |
323 | |
324 | /* |
325 | * If non-zero, defines the maximum length of string that can |
326 | * be passed to write_string; defaults to 64 |
327 | */ |
328 | size_t max_write_len; |
329 | |
330 | int (*open)(struct inode *inode, struct file *file); |
331 | ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, |
332 | struct file *file, |
333 | char __user *buf, size_t nbytes, loff_t *ppos); |
334 | /* |
335 | * read_u64() is a shortcut for the common case of returning a |
336 | * single integer. Use it in place of read() |
337 | */ |
338 | u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft); |
339 | /* |
340 | * read_s64() is a signed version of read_u64() |
341 | */ |
342 | s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft); |
343 | /* |
344 | * read_map() is used for defining a map of key/value |
345 | * pairs. It should call cb->fill(cb, key, value) for each |
346 | * entry. The key/value pairs (and their ordering) should not |
347 | * change between reboots. |
348 | */ |
349 | int (*read_map)(struct cgroup *cont, struct cftype *cft, |
350 | struct cgroup_map_cb *cb); |
351 | /* |
352 | * read_seq_string() is used for outputting a simple sequence |
353 | * using seqfile. |
354 | */ |
355 | int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, |
356 | struct seq_file *m); |
357 | |
358 | ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, |
359 | struct file *file, |
360 | const char __user *buf, size_t nbytes, loff_t *ppos); |
361 | |
362 | /* |
363 | * write_u64() is a shortcut for the common case of accepting |
364 | * a single integer (as parsed by simple_strtoull) from |
365 | * userspace. Use in place of write(); return 0 or error. |
366 | */ |
367 | int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val); |
368 | /* |
369 | * write_s64() is a signed version of write_u64() |
370 | */ |
371 | int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val); |
372 | |
373 | /* |
374 | * write_string() is passed a nul-terminated kernelspace |
375 | * buffer of maximum length determined by max_write_len. |
376 | * Returns 0 or -ve error code. |
377 | */ |
378 | int (*write_string)(struct cgroup *cgrp, struct cftype *cft, |
379 | const char *buffer); |
380 | /* |
381 | * trigger() callback can be used to get some kick from the |
382 | * userspace, when the actual string written is not important |
383 | * at all. The private field can be used to determine the |
384 | * kick type for multiplexing. |
385 | */ |
386 | int (*trigger)(struct cgroup *cgrp, unsigned int event); |
387 | |
388 | int (*release)(struct inode *inode, struct file *file); |
389 | |
390 | /* |
391 | * register_event() callback will be used to add new userspace |
392 | * waiter for changes related to the cftype. Implement it if |
393 | * you want to provide this functionality. Use eventfd_signal() |
394 | * on eventfd to send notification to userspace. |
395 | */ |
396 | int (*register_event)(struct cgroup *cgrp, struct cftype *cft, |
397 | struct eventfd_ctx *eventfd, const char *args); |
398 | /* |
399 | * unregister_event() callback will be called when userspace |
400 | * closes the eventfd or on cgroup removing. |
401 | * This callback must be implemented, if you want provide |
402 | * notification functionality. |
403 | */ |
404 | void (*unregister_event)(struct cgroup *cgrp, struct cftype *cft, |
405 | struct eventfd_ctx *eventfd); |
406 | }; |
407 | |
408 | struct cgroup_scanner { |
409 | struct cgroup *cg; |
410 | int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); |
411 | void (*process_task)(struct task_struct *p, |
412 | struct cgroup_scanner *scan); |
413 | struct ptr_heap *heap; |
414 | void *data; |
415 | }; |
416 | |
417 | /* |
418 | * Add a new file to the given cgroup directory. Should only be |
419 | * called by subsystems from within a populate() method |
420 | */ |
421 | int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
422 | const struct cftype *cft); |
423 | |
424 | /* |
425 | * Add a set of new files to the given cgroup directory. Should |
426 | * only be called by subsystems from within a populate() method |
427 | */ |
428 | int cgroup_add_files(struct cgroup *cgrp, |
429 | struct cgroup_subsys *subsys, |
430 | const struct cftype cft[], |
431 | int count); |
432 | |
433 | int cgroup_is_removed(const struct cgroup *cgrp); |
434 | |
435 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); |
436 | |
437 | int cgroup_task_count(const struct cgroup *cgrp); |
438 | |
439 | /* Return true if cgrp is a descendant of the task's cgroup */ |
440 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task); |
441 | |
442 | /* |
443 | * When the subsys has to access css and may add permanent refcnt to css, |
444 | * it should take care of racy conditions with rmdir(). Following set of |
445 | * functions, is for stop/restart rmdir if necessary. |
446 | * Because these will call css_get/put, "css" should be alive css. |
447 | * |
448 | * cgroup_exclude_rmdir(); |
449 | * ...do some jobs which may access arbitrary empty cgroup |
450 | * cgroup_release_and_wakeup_rmdir(); |
451 | * |
452 | * When someone removes a cgroup while cgroup_exclude_rmdir() holds it, |
453 | * it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up. |
454 | */ |
455 | |
456 | void cgroup_exclude_rmdir(struct cgroup_subsys_state *css); |
457 | void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css); |
458 | |
459 | /* |
460 | * Control Group subsystem type. |
461 | * See Documentation/cgroups/cgroups.txt for details |
462 | */ |
463 | |
464 | struct cgroup_subsys { |
465 | struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss, |
466 | struct cgroup *cgrp); |
467 | int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); |
468 | void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); |
469 | int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, |
470 | struct task_struct *tsk); |
471 | int (*can_attach_task)(struct cgroup *cgrp, struct task_struct *tsk); |
472 | void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, |
473 | struct task_struct *tsk); |
474 | void (*pre_attach)(struct cgroup *cgrp); |
475 | void (*attach_task)(struct cgroup *cgrp, struct task_struct *tsk); |
476 | void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, |
477 | struct cgroup *old_cgrp, struct task_struct *tsk); |
478 | void (*fork)(struct cgroup_subsys *ss, struct task_struct *task); |
479 | void (*exit)(struct cgroup_subsys *ss, struct cgroup *cgrp, |
480 | struct cgroup *old_cgrp, struct task_struct *task); |
481 | int (*populate)(struct cgroup_subsys *ss, |
482 | struct cgroup *cgrp); |
483 | void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); |
484 | void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); |
485 | |
486 | int subsys_id; |
487 | int active; |
488 | int disabled; |
489 | int early_init; |
490 | /* |
491 | * True if this subsys uses ID. ID is not available before cgroup_init() |
492 | * (not available in early_init time.) |
493 | */ |
494 | bool use_id; |
495 | #define MAX_CGROUP_TYPE_NAMELEN 32 |
496 | const char *name; |
497 | |
498 | /* |
499 | * Protects sibling/children links of cgroups in this |
500 | * hierarchy, plus protects which hierarchy (or none) the |
501 | * subsystem is a part of (i.e. root/sibling). To avoid |
502 | * potential deadlocks, the following operations should not be |
503 | * undertaken while holding any hierarchy_mutex: |
504 | * |
505 | * - allocating memory |
506 | * - initiating hotplug events |
507 | */ |
508 | struct mutex hierarchy_mutex; |
509 | struct lock_class_key subsys_key; |
510 | |
511 | /* |
512 | * Link to parent, and list entry in parent's children. |
513 | * Protected by this->hierarchy_mutex and cgroup_lock() |
514 | */ |
515 | struct cgroupfs_root *root; |
516 | struct list_head sibling; |
517 | /* used when use_id == true */ |
518 | struct idr idr; |
519 | spinlock_t id_lock; |
520 | |
521 | /* should be defined only by modular subsystems */ |
522 | struct module *module; |
523 | }; |
524 | |
525 | #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; |
526 | #include <linux/cgroup_subsys.h> |
527 | #undef SUBSYS |
528 | |
529 | static inline struct cgroup_subsys_state *cgroup_subsys_state( |
530 | struct cgroup *cgrp, int subsys_id) |
531 | { |
532 | return cgrp->subsys[subsys_id]; |
533 | } |
534 | |
535 | /* |
536 | * function to get the cgroup_subsys_state which allows for extra |
537 | * rcu_dereference_check() conditions, such as locks used during the |
538 | * cgroup_subsys::attach() methods. |
539 | */ |
540 | #define task_subsys_state_check(task, subsys_id, __c) \ |
541 | rcu_dereference_check(task->cgroups->subsys[subsys_id], \ |
542 | rcu_read_lock_held() || \ |
543 | lockdep_is_held(&task->alloc_lock) || \ |
544 | cgroup_lock_is_held() || (__c)) |
545 | |
546 | static inline struct cgroup_subsys_state * |
547 | task_subsys_state(struct task_struct *task, int subsys_id) |
548 | { |
549 | return task_subsys_state_check(task, subsys_id, false); |
550 | } |
551 | |
552 | static inline struct cgroup* task_cgroup(struct task_struct *task, |
553 | int subsys_id) |
554 | { |
555 | return task_subsys_state(task, subsys_id)->cgroup; |
556 | } |
557 | |
558 | /* A cgroup_iter should be treated as an opaque object */ |
559 | struct cgroup_iter { |
560 | struct list_head *cg_link; |
561 | struct list_head *task; |
562 | }; |
563 | |
564 | /* |
565 | * To iterate across the tasks in a cgroup: |
566 | * |
567 | * 1) call cgroup_iter_start to initialize an iterator |
568 | * |
569 | * 2) call cgroup_iter_next() to retrieve member tasks until it |
570 | * returns NULL or until you want to end the iteration |
571 | * |
572 | * 3) call cgroup_iter_end() to destroy the iterator. |
573 | * |
574 | * Or, call cgroup_scan_tasks() to iterate through every task in a |
575 | * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling |
576 | * the test_task() callback, but not while calling the process_task() |
577 | * callback. |
578 | */ |
579 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); |
580 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
581 | struct cgroup_iter *it); |
582 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); |
583 | int cgroup_scan_tasks(struct cgroup_scanner *scan); |
584 | int cgroup_attach_task(struct cgroup *, struct task_struct *); |
585 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); |
586 | |
587 | static inline int cgroup_attach_task_current_cg(struct task_struct *tsk) |
588 | { |
589 | return cgroup_attach_task_all(current, tsk); |
590 | } |
591 | |
592 | /* |
593 | * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works |
594 | * if cgroup_subsys.use_id == true. It can be used for looking up and scanning. |
595 | * CSS ID is assigned at cgroup allocation (create) automatically |
596 | * and removed when subsys calls free_css_id() function. This is because |
597 | * the lifetime of cgroup_subsys_state is subsys's matter. |
598 | * |
599 | * Looking up and scanning function should be called under rcu_read_lock(). |
600 | * Taking cgroup_mutex()/hierarchy_mutex() is not necessary for following calls. |
601 | * But the css returned by this routine can be "not populated yet" or "being |
602 | * destroyed". The caller should check css and cgroup's status. |
603 | */ |
604 | |
605 | /* |
606 | * Typically Called at ->destroy(), or somewhere the subsys frees |
607 | * cgroup_subsys_state. |
608 | */ |
609 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css); |
610 | |
611 | /* Find a cgroup_subsys_state which has given ID */ |
612 | |
613 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id); |
614 | |
615 | /* |
616 | * Get a cgroup whose id is greater than or equal to id under tree of root. |
617 | * Returning a cgroup_subsys_state or NULL. |
618 | */ |
619 | struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id, |
620 | struct cgroup_subsys_state *root, int *foundid); |
621 | |
622 | /* Returns true if root is ancestor of cg */ |
623 | bool css_is_ancestor(struct cgroup_subsys_state *cg, |
624 | const struct cgroup_subsys_state *root); |
625 | |
626 | /* Get id and depth of css */ |
627 | unsigned short css_id(struct cgroup_subsys_state *css); |
628 | unsigned short css_depth(struct cgroup_subsys_state *css); |
629 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id); |
630 | |
631 | #else /* !CONFIG_CGROUPS */ |
632 | |
633 | static inline int cgroup_init_early(void) { return 0; } |
634 | static inline int cgroup_init(void) { return 0; } |
635 | static inline void cgroup_fork(struct task_struct *p) {} |
636 | static inline void cgroup_fork_callbacks(struct task_struct *p) {} |
637 | static inline void cgroup_post_fork(struct task_struct *p) {} |
638 | static inline void cgroup_exit(struct task_struct *p, int callbacks) {} |
639 | |
640 | static inline void cgroup_lock(void) {} |
641 | static inline void cgroup_unlock(void) {} |
642 | static inline int cgroupstats_build(struct cgroupstats *stats, |
643 | struct dentry *dentry) |
644 | { |
645 | return -EINVAL; |
646 | } |
647 | |
648 | /* No cgroups - nothing to do */ |
649 | static inline int cgroup_attach_task_all(struct task_struct *from, |
650 | struct task_struct *t) |
651 | { |
652 | return 0; |
653 | } |
654 | static inline int cgroup_attach_task_current_cg(struct task_struct *t) |
655 | { |
656 | return 0; |
657 | } |
658 | |
659 | #endif /* !CONFIG_CGROUPS */ |
660 | |
661 | #endif /* _LINUX_CGROUP_H */ |
662 |
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