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ddbcc7e8 PM |
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> | |
ddbcc7e8 PM |
12 | #include <linux/cpumask.h> |
13 | #include <linux/nodemask.h> | |
14 | #include <linux/rcupdate.h> | |
846c7bb0 | 15 | #include <linux/cgroupstats.h> |
31a7df01 | 16 | #include <linux/prio_heap.h> |
cc31edce | 17 | #include <linux/rwsem.h> |
38460b48 | 18 | #include <linux/idr.h> |
ddbcc7e8 PM |
19 | |
20 | #ifdef CONFIG_CGROUPS | |
21 | ||
22 | struct cgroupfs_root; | |
23 | struct cgroup_subsys; | |
24 | struct inode; | |
84eea842 | 25 | struct cgroup; |
38460b48 | 26 | struct css_id; |
ddbcc7e8 PM |
27 | |
28 | extern int cgroup_init_early(void); | |
29 | extern int cgroup_init(void); | |
ddbcc7e8 | 30 | extern void cgroup_lock(void); |
84eea842 | 31 | extern bool cgroup_lock_live_group(struct cgroup *cgrp); |
ddbcc7e8 | 32 | extern void cgroup_unlock(void); |
b4f48b63 PM |
33 | extern void cgroup_fork(struct task_struct *p); |
34 | extern void cgroup_fork_callbacks(struct task_struct *p); | |
817929ec | 35 | extern void cgroup_post_fork(struct task_struct *p); |
b4f48b63 | 36 | extern void cgroup_exit(struct task_struct *p, int run_callbacks); |
846c7bb0 BS |
37 | extern int cgroupstats_build(struct cgroupstats *stats, |
38 | struct dentry *dentry); | |
ddbcc7e8 | 39 | |
a424316c PM |
40 | extern struct file_operations proc_cgroup_operations; |
41 | ||
817929ec PM |
42 | /* Define the enumeration of all cgroup subsystems */ |
43 | #define SUBSYS(_x) _x ## _subsys_id, | |
44 | enum cgroup_subsys_id { | |
45 | #include <linux/cgroup_subsys.h> | |
46 | CGROUP_SUBSYS_COUNT | |
47 | }; | |
48 | #undef SUBSYS | |
49 | ||
ddbcc7e8 PM |
50 | /* Per-subsystem/per-cgroup state maintained by the system. */ |
51 | struct cgroup_subsys_state { | |
d20a390a PM |
52 | /* |
53 | * The cgroup that this subsystem is attached to. Useful | |
ddbcc7e8 | 54 | * for subsystems that want to know about the cgroup |
d20a390a PM |
55 | * hierarchy structure |
56 | */ | |
ddbcc7e8 PM |
57 | struct cgroup *cgroup; |
58 | ||
d20a390a PM |
59 | /* |
60 | * State maintained by the cgroup system to allow subsystems | |
e7c5ec91 | 61 | * to be "busy". Should be accessed via css_get(), |
d20a390a PM |
62 | * css_tryget() and and css_put(). |
63 | */ | |
ddbcc7e8 PM |
64 | |
65 | atomic_t refcnt; | |
66 | ||
67 | unsigned long flags; | |
38460b48 KH |
68 | /* ID for this css, if possible */ |
69 | struct css_id *id; | |
ddbcc7e8 PM |
70 | }; |
71 | ||
72 | /* bits in struct cgroup_subsys_state flags field */ | |
73 | enum { | |
74 | CSS_ROOT, /* This CSS is the root of the subsystem */ | |
e7c5ec91 | 75 | CSS_REMOVED, /* This CSS is dead */ |
ddbcc7e8 PM |
76 | }; |
77 | ||
78 | /* | |
e7c5ec91 PM |
79 | * Call css_get() to hold a reference on the css; it can be used |
80 | * for a reference obtained via: | |
81 | * - an existing ref-counted reference to the css | |
82 | * - task->cgroups for a locked task | |
ddbcc7e8 PM |
83 | */ |
84 | ||
85 | static inline void css_get(struct cgroup_subsys_state *css) | |
86 | { | |
87 | /* We don't need to reference count the root state */ | |
88 | if (!test_bit(CSS_ROOT, &css->flags)) | |
89 | atomic_inc(&css->refcnt); | |
90 | } | |
e7c5ec91 PM |
91 | |
92 | static inline bool css_is_removed(struct cgroup_subsys_state *css) | |
93 | { | |
94 | return test_bit(CSS_REMOVED, &css->flags); | |
95 | } | |
96 | ||
97 | /* | |
98 | * Call css_tryget() to take a reference on a css if your existing | |
99 | * (known-valid) reference isn't already ref-counted. Returns false if | |
100 | * the css has been destroyed. | |
101 | */ | |
102 | ||
103 | static inline bool css_tryget(struct cgroup_subsys_state *css) | |
104 | { | |
105 | if (test_bit(CSS_ROOT, &css->flags)) | |
106 | return true; | |
107 | while (!atomic_inc_not_zero(&css->refcnt)) { | |
108 | if (test_bit(CSS_REMOVED, &css->flags)) | |
109 | return false; | |
804b3c28 | 110 | cpu_relax(); |
e7c5ec91 PM |
111 | } |
112 | return true; | |
113 | } | |
114 | ||
ddbcc7e8 PM |
115 | /* |
116 | * css_put() should be called to release a reference taken by | |
e7c5ec91 | 117 | * css_get() or css_tryget() |
ddbcc7e8 PM |
118 | */ |
119 | ||
81a6a5cd | 120 | extern void __css_put(struct cgroup_subsys_state *css); |
ddbcc7e8 PM |
121 | static inline void css_put(struct cgroup_subsys_state *css) |
122 | { | |
123 | if (!test_bit(CSS_ROOT, &css->flags)) | |
81a6a5cd | 124 | __css_put(css); |
ddbcc7e8 PM |
125 | } |
126 | ||
3116f0e3 PM |
127 | /* bits in struct cgroup flags field */ |
128 | enum { | |
129 | /* Control Group is dead */ | |
130 | CGRP_REMOVED, | |
d20a390a PM |
131 | /* |
132 | * Control Group has previously had a child cgroup or a task, | |
133 | * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) | |
134 | */ | |
3116f0e3 PM |
135 | CGRP_RELEASABLE, |
136 | /* Control Group requires release notifications to userspace */ | |
137 | CGRP_NOTIFY_ON_RELEASE, | |
ec64f515 KH |
138 | /* |
139 | * A thread in rmdir() is wating for this cgroup. | |
140 | */ | |
141 | CGRP_WAIT_ON_RMDIR, | |
3116f0e3 PM |
142 | }; |
143 | ||
102a775e BB |
144 | struct cgroup_pidlist { |
145 | /* protects the other fields */ | |
146 | struct rw_semaphore mutex; | |
147 | /* array of xids */ | |
148 | pid_t *list; | |
149 | /* how many elements the above list has */ | |
150 | int length; | |
151 | /* how many files are using the current array */ | |
152 | int use_count; | |
153 | }; | |
154 | ||
ddbcc7e8 PM |
155 | struct cgroup { |
156 | unsigned long flags; /* "unsigned long" so bitops work */ | |
157 | ||
d20a390a PM |
158 | /* |
159 | * count users of this cgroup. >0 means busy, but doesn't | |
160 | * necessarily indicate the number of tasks in the cgroup | |
161 | */ | |
ddbcc7e8 PM |
162 | atomic_t count; |
163 | ||
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 | ||
d20a390a | 171 | struct cgroup *parent; /* my parent */ |
a47295e6 | 172 | struct dentry *dentry; /* cgroup fs entry, RCU protected */ |
ddbcc7e8 PM |
173 | |
174 | /* Private pointers for each registered subsystem */ | |
175 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; | |
176 | ||
177 | struct cgroupfs_root *root; | |
178 | struct cgroup *top_cgroup; | |
817929ec PM |
179 | |
180 | /* | |
181 | * List of cg_cgroup_links pointing at css_sets with | |
182 | * tasks in this cgroup. Protected by css_set_lock | |
183 | */ | |
184 | struct list_head css_sets; | |
81a6a5cd PM |
185 | |
186 | /* | |
187 | * Linked list running through all cgroups that can | |
188 | * potentially be reaped by the release agent. Protected by | |
189 | * release_list_lock | |
190 | */ | |
191 | struct list_head release_list; | |
cc31edce | 192 | |
102a775e BB |
193 | /* we will have two separate pidlists, one for pids (the tasks file) |
194 | * and one for tgids (the procs file). */ | |
195 | struct cgroup_pidlist tasks, procs; | |
a47295e6 PM |
196 | |
197 | /* For RCU-protected deletion */ | |
198 | struct rcu_head rcu_head; | |
817929ec PM |
199 | }; |
200 | ||
d20a390a PM |
201 | /* |
202 | * A css_set is a structure holding pointers to a set of | |
817929ec PM |
203 | * cgroup_subsys_state objects. This saves space in the task struct |
204 | * object and speeds up fork()/exit(), since a single inc/dec and a | |
d20a390a PM |
205 | * list_add()/del() can bump the reference count on the entire cgroup |
206 | * set for a task. | |
817929ec PM |
207 | */ |
208 | ||
209 | struct css_set { | |
210 | ||
211 | /* Reference count */ | |
146aa1bd | 212 | atomic_t refcount; |
817929ec | 213 | |
472b1053 LZ |
214 | /* |
215 | * List running through all cgroup groups in the same hash | |
216 | * slot. Protected by css_set_lock | |
217 | */ | |
218 | struct hlist_node hlist; | |
219 | ||
817929ec PM |
220 | /* |
221 | * List running through all tasks using this cgroup | |
222 | * group. Protected by css_set_lock | |
223 | */ | |
224 | struct list_head tasks; | |
225 | ||
226 | /* | |
227 | * List of cg_cgroup_link objects on link chains from | |
228 | * cgroups referenced from this css_set. Protected by | |
229 | * css_set_lock | |
230 | */ | |
231 | struct list_head cg_links; | |
232 | ||
233 | /* | |
234 | * Set of subsystem states, one for each subsystem. This array | |
235 | * is immutable after creation apart from the init_css_set | |
236 | * during subsystem registration (at boot time). | |
237 | */ | |
238 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; | |
ddbcc7e8 PM |
239 | }; |
240 | ||
91796569 PM |
241 | /* |
242 | * cgroup_map_cb is an abstract callback API for reporting map-valued | |
243 | * control files | |
244 | */ | |
245 | ||
246 | struct cgroup_map_cb { | |
247 | int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); | |
248 | void *state; | |
249 | }; | |
250 | ||
d20a390a PM |
251 | /* |
252 | * struct cftype: handler definitions for cgroup control files | |
ddbcc7e8 PM |
253 | * |
254 | * When reading/writing to a file: | |
a043e3b2 | 255 | * - the cgroup to use is file->f_dentry->d_parent->d_fsdata |
ddbcc7e8 PM |
256 | * - the 'cftype' of the file is file->f_dentry->d_fsdata |
257 | */ | |
258 | ||
259 | #define MAX_CFTYPE_NAME 64 | |
260 | struct cftype { | |
d20a390a PM |
261 | /* |
262 | * By convention, the name should begin with the name of the | |
263 | * subsystem, followed by a period | |
264 | */ | |
ddbcc7e8 PM |
265 | char name[MAX_CFTYPE_NAME]; |
266 | int private; | |
099fca32 LZ |
267 | /* |
268 | * If not 0, file mode is set to this value, otherwise it will | |
269 | * be figured out automatically | |
270 | */ | |
271 | mode_t mode; | |
db3b1497 PM |
272 | |
273 | /* | |
274 | * If non-zero, defines the maximum length of string that can | |
275 | * be passed to write_string; defaults to 64 | |
276 | */ | |
277 | size_t max_write_len; | |
278 | ||
ce16b49d PM |
279 | int (*open)(struct inode *inode, struct file *file); |
280 | ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, | |
281 | struct file *file, | |
282 | char __user *buf, size_t nbytes, loff_t *ppos); | |
ddbcc7e8 | 283 | /* |
f4c753b7 | 284 | * read_u64() is a shortcut for the common case of returning a |
ddbcc7e8 PM |
285 | * single integer. Use it in place of read() |
286 | */ | |
ce16b49d | 287 | u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft); |
e73d2c61 PM |
288 | /* |
289 | * read_s64() is a signed version of read_u64() | |
290 | */ | |
ce16b49d | 291 | s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft); |
91796569 PM |
292 | /* |
293 | * read_map() is used for defining a map of key/value | |
294 | * pairs. It should call cb->fill(cb, key, value) for each | |
295 | * entry. The key/value pairs (and their ordering) should not | |
296 | * change between reboots. | |
297 | */ | |
ce16b49d PM |
298 | int (*read_map)(struct cgroup *cont, struct cftype *cft, |
299 | struct cgroup_map_cb *cb); | |
29486df3 SH |
300 | /* |
301 | * read_seq_string() is used for outputting a simple sequence | |
302 | * using seqfile. | |
303 | */ | |
ce16b49d PM |
304 | int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, |
305 | struct seq_file *m); | |
91796569 | 306 | |
ce16b49d PM |
307 | ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, |
308 | struct file *file, | |
309 | const char __user *buf, size_t nbytes, loff_t *ppos); | |
355e0c48 PM |
310 | |
311 | /* | |
f4c753b7 | 312 | * write_u64() is a shortcut for the common case of accepting |
355e0c48 PM |
313 | * a single integer (as parsed by simple_strtoull) from |
314 | * userspace. Use in place of write(); return 0 or error. | |
315 | */ | |
ce16b49d | 316 | int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val); |
e73d2c61 PM |
317 | /* |
318 | * write_s64() is a signed version of write_u64() | |
319 | */ | |
ce16b49d | 320 | int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val); |
355e0c48 | 321 | |
db3b1497 PM |
322 | /* |
323 | * write_string() is passed a nul-terminated kernelspace | |
324 | * buffer of maximum length determined by max_write_len. | |
325 | * Returns 0 or -ve error code. | |
326 | */ | |
327 | int (*write_string)(struct cgroup *cgrp, struct cftype *cft, | |
328 | const char *buffer); | |
d447ea2f PE |
329 | /* |
330 | * trigger() callback can be used to get some kick from the | |
331 | * userspace, when the actual string written is not important | |
332 | * at all. The private field can be used to determine the | |
333 | * kick type for multiplexing. | |
334 | */ | |
335 | int (*trigger)(struct cgroup *cgrp, unsigned int event); | |
336 | ||
ce16b49d | 337 | int (*release)(struct inode *inode, struct file *file); |
ddbcc7e8 PM |
338 | }; |
339 | ||
31a7df01 CW |
340 | struct cgroup_scanner { |
341 | struct cgroup *cg; | |
342 | int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); | |
343 | void (*process_task)(struct task_struct *p, | |
344 | struct cgroup_scanner *scan); | |
345 | struct ptr_heap *heap; | |
bd1a8ab7 | 346 | void *data; |
31a7df01 CW |
347 | }; |
348 | ||
d20a390a PM |
349 | /* |
350 | * Add a new file to the given cgroup directory. Should only be | |
351 | * called by subsystems from within a populate() method | |
352 | */ | |
ffd2d883 | 353 | int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
ddbcc7e8 PM |
354 | const struct cftype *cft); |
355 | ||
d20a390a PM |
356 | /* |
357 | * Add a set of new files to the given cgroup directory. Should | |
358 | * only be called by subsystems from within a populate() method | |
359 | */ | |
ffd2d883 | 360 | int cgroup_add_files(struct cgroup *cgrp, |
ddbcc7e8 PM |
361 | struct cgroup_subsys *subsys, |
362 | const struct cftype cft[], | |
363 | int count); | |
364 | ||
ffd2d883 | 365 | int cgroup_is_removed(const struct cgroup *cgrp); |
ddbcc7e8 | 366 | |
ffd2d883 | 367 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); |
ddbcc7e8 | 368 | |
ffd2d883 | 369 | int cgroup_task_count(const struct cgroup *cgrp); |
bbcb81d0 | 370 | |
313e924c GN |
371 | /* Return true if cgrp is a descendant of the task's cgroup */ |
372 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task); | |
ddbcc7e8 | 373 | |
88703267 KH |
374 | /* |
375 | * When the subsys has to access css and may add permanent refcnt to css, | |
376 | * it should take care of racy conditions with rmdir(). Following set of | |
377 | * functions, is for stop/restart rmdir if necessary. | |
378 | * Because these will call css_get/put, "css" should be alive css. | |
379 | * | |
380 | * cgroup_exclude_rmdir(); | |
381 | * ...do some jobs which may access arbitrary empty cgroup | |
382 | * cgroup_release_and_wakeup_rmdir(); | |
383 | * | |
384 | * When someone removes a cgroup while cgroup_exclude_rmdir() holds it, | |
385 | * it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up. | |
386 | */ | |
387 | ||
388 | void cgroup_exclude_rmdir(struct cgroup_subsys_state *css); | |
389 | void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css); | |
390 | ||
21acb9ca TLSC |
391 | /* |
392 | * Control Group subsystem type. | |
393 | * See Documentation/cgroups/cgroups.txt for details | |
394 | */ | |
ddbcc7e8 PM |
395 | |
396 | struct cgroup_subsys { | |
397 | struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss, | |
ffd2d883 | 398 | struct cgroup *cgrp); |
ec64f515 | 399 | int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); |
ffd2d883 | 400 | void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); |
ddbcc7e8 | 401 | int (*can_attach)(struct cgroup_subsys *ss, |
ffd2d883 LZ |
402 | struct cgroup *cgrp, struct task_struct *tsk); |
403 | void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, | |
404 | struct cgroup *old_cgrp, struct task_struct *tsk); | |
ddbcc7e8 PM |
405 | void (*fork)(struct cgroup_subsys *ss, struct task_struct *task); |
406 | void (*exit)(struct cgroup_subsys *ss, struct task_struct *task); | |
407 | int (*populate)(struct cgroup_subsys *ss, | |
ffd2d883 LZ |
408 | struct cgroup *cgrp); |
409 | void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); | |
ddbcc7e8 | 410 | void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); |
e5991371 | 411 | |
ddbcc7e8 PM |
412 | int subsys_id; |
413 | int active; | |
8bab8dde | 414 | int disabled; |
ddbcc7e8 | 415 | int early_init; |
38460b48 KH |
416 | /* |
417 | * True if this subsys uses ID. ID is not available before cgroup_init() | |
418 | * (not available in early_init time.) | |
419 | */ | |
420 | bool use_id; | |
ddbcc7e8 PM |
421 | #define MAX_CGROUP_TYPE_NAMELEN 32 |
422 | const char *name; | |
423 | ||
999cd8a4 PM |
424 | /* |
425 | * Protects sibling/children links of cgroups in this | |
426 | * hierarchy, plus protects which hierarchy (or none) the | |
427 | * subsystem is a part of (i.e. root/sibling). To avoid | |
428 | * potential deadlocks, the following operations should not be | |
429 | * undertaken while holding any hierarchy_mutex: | |
430 | * | |
431 | * - allocating memory | |
432 | * - initiating hotplug events | |
433 | */ | |
434 | struct mutex hierarchy_mutex; | |
cfebe563 | 435 | struct lock_class_key subsys_key; |
ddbcc7e8 | 436 | |
999cd8a4 PM |
437 | /* |
438 | * Link to parent, and list entry in parent's children. | |
439 | * Protected by this->hierarchy_mutex and cgroup_lock() | |
440 | */ | |
441 | struct cgroupfs_root *root; | |
ddbcc7e8 | 442 | struct list_head sibling; |
38460b48 KH |
443 | /* used when use_id == true */ |
444 | struct idr idr; | |
445 | spinlock_t id_lock; | |
ddbcc7e8 PM |
446 | }; |
447 | ||
448 | #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; | |
449 | #include <linux/cgroup_subsys.h> | |
450 | #undef SUBSYS | |
451 | ||
452 | static inline struct cgroup_subsys_state *cgroup_subsys_state( | |
ffd2d883 | 453 | struct cgroup *cgrp, int subsys_id) |
ddbcc7e8 | 454 | { |
ffd2d883 | 455 | return cgrp->subsys[subsys_id]; |
ddbcc7e8 PM |
456 | } |
457 | ||
458 | static inline struct cgroup_subsys_state *task_subsys_state( | |
459 | struct task_struct *task, int subsys_id) | |
460 | { | |
817929ec | 461 | return rcu_dereference(task->cgroups->subsys[subsys_id]); |
ddbcc7e8 PM |
462 | } |
463 | ||
464 | static inline struct cgroup* task_cgroup(struct task_struct *task, | |
465 | int subsys_id) | |
466 | { | |
467 | return task_subsys_state(task, subsys_id)->cgroup; | |
468 | } | |
469 | ||
e885dcde SH |
470 | int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss, |
471 | char *nodename); | |
697f4161 | 472 | |
817929ec PM |
473 | /* A cgroup_iter should be treated as an opaque object */ |
474 | struct cgroup_iter { | |
475 | struct list_head *cg_link; | |
476 | struct list_head *task; | |
477 | }; | |
478 | ||
d20a390a PM |
479 | /* |
480 | * To iterate across the tasks in a cgroup: | |
817929ec PM |
481 | * |
482 | * 1) call cgroup_iter_start to intialize an iterator | |
483 | * | |
484 | * 2) call cgroup_iter_next() to retrieve member tasks until it | |
485 | * returns NULL or until you want to end the iteration | |
486 | * | |
487 | * 3) call cgroup_iter_end() to destroy the iterator. | |
31a7df01 | 488 | * |
d20a390a PM |
489 | * Or, call cgroup_scan_tasks() to iterate through every task in a |
490 | * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling | |
491 | * the test_task() callback, but not while calling the process_task() | |
492 | * callback. | |
817929ec | 493 | */ |
ffd2d883 LZ |
494 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); |
495 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, | |
817929ec | 496 | struct cgroup_iter *it); |
ffd2d883 | 497 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); |
31a7df01 | 498 | int cgroup_scan_tasks(struct cgroup_scanner *scan); |
956db3ca | 499 | int cgroup_attach_task(struct cgroup *, struct task_struct *); |
817929ec | 500 | |
38460b48 KH |
501 | /* |
502 | * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works | |
503 | * if cgroup_subsys.use_id == true. It can be used for looking up and scanning. | |
504 | * CSS ID is assigned at cgroup allocation (create) automatically | |
505 | * and removed when subsys calls free_css_id() function. This is because | |
506 | * the lifetime of cgroup_subsys_state is subsys's matter. | |
507 | * | |
508 | * Looking up and scanning function should be called under rcu_read_lock(). | |
509 | * Taking cgroup_mutex()/hierarchy_mutex() is not necessary for following calls. | |
510 | * But the css returned by this routine can be "not populated yet" or "being | |
511 | * destroyed". The caller should check css and cgroup's status. | |
512 | */ | |
513 | ||
514 | /* | |
515 | * Typically Called at ->destroy(), or somewhere the subsys frees | |
516 | * cgroup_subsys_state. | |
517 | */ | |
518 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css); | |
519 | ||
520 | /* Find a cgroup_subsys_state which has given ID */ | |
521 | ||
522 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id); | |
523 | ||
524 | /* | |
525 | * Get a cgroup whose id is greater than or equal to id under tree of root. | |
526 | * Returning a cgroup_subsys_state or NULL. | |
527 | */ | |
528 | struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id, | |
529 | struct cgroup_subsys_state *root, int *foundid); | |
530 | ||
531 | /* Returns true if root is ancestor of cg */ | |
532 | bool css_is_ancestor(struct cgroup_subsys_state *cg, | |
0b7f569e | 533 | const struct cgroup_subsys_state *root); |
38460b48 KH |
534 | |
535 | /* Get id and depth of css */ | |
536 | unsigned short css_id(struct cgroup_subsys_state *css); | |
537 | unsigned short css_depth(struct cgroup_subsys_state *css); | |
538 | ||
ddbcc7e8 PM |
539 | #else /* !CONFIG_CGROUPS */ |
540 | ||
541 | static inline int cgroup_init_early(void) { return 0; } | |
542 | static inline int cgroup_init(void) { return 0; } | |
b4f48b63 PM |
543 | static inline void cgroup_fork(struct task_struct *p) {} |
544 | static inline void cgroup_fork_callbacks(struct task_struct *p) {} | |
817929ec | 545 | static inline void cgroup_post_fork(struct task_struct *p) {} |
b4f48b63 | 546 | static inline void cgroup_exit(struct task_struct *p, int callbacks) {} |
ddbcc7e8 PM |
547 | |
548 | static inline void cgroup_lock(void) {} | |
549 | static inline void cgroup_unlock(void) {} | |
846c7bb0 BS |
550 | static inline int cgroupstats_build(struct cgroupstats *stats, |
551 | struct dentry *dentry) | |
552 | { | |
553 | return -EINVAL; | |
554 | } | |
ddbcc7e8 PM |
555 | |
556 | #endif /* !CONFIG_CGROUPS */ | |
557 | ||
558 | #endif /* _LINUX_CGROUP_H */ |