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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> | |
eb6fd504 | 15 | #include <linux/rculist.h> |
846c7bb0 | 16 | #include <linux/cgroupstats.h> |
cc31edce | 17 | #include <linux/rwsem.h> |
38460b48 | 18 | #include <linux/idr.h> |
48ddbe19 | 19 | #include <linux/workqueue.h> |
25a7e684 | 20 | #include <linux/fs.h> |
d3daf28d | 21 | #include <linux/percpu-refcount.h> |
7da11279 | 22 | #include <linux/seq_file.h> |
2bd59d48 | 23 | #include <linux/kernfs.h> |
f8f22e53 | 24 | #include <linux/wait.h> |
ddbcc7e8 PM |
25 | |
26 | #ifdef CONFIG_CGROUPS | |
27 | ||
3dd06ffa | 28 | struct cgroup_root; |
ddbcc7e8 PM |
29 | struct cgroup_subsys; |
30 | struct inode; | |
84eea842 | 31 | struct cgroup; |
ddbcc7e8 PM |
32 | |
33 | extern int cgroup_init_early(void); | |
34 | extern int cgroup_init(void); | |
b4f48b63 | 35 | extern void cgroup_fork(struct task_struct *p); |
817929ec | 36 | extern void cgroup_post_fork(struct task_struct *p); |
1ec41830 | 37 | extern void cgroup_exit(struct task_struct *p); |
846c7bb0 BS |
38 | extern int cgroupstats_build(struct cgroupstats *stats, |
39 | struct dentry *dentry); | |
ddbcc7e8 | 40 | |
8d8b97ba | 41 | extern int proc_cgroup_show(struct seq_file *, void *); |
a424316c | 42 | |
3ed80a62 | 43 | /* define the enumeration of all cgroup subsystems */ |
073219e9 | 44 | #define SUBSYS(_x) _x ## _cgrp_id, |
817929ec PM |
45 | enum cgroup_subsys_id { |
46 | #include <linux/cgroup_subsys.h> | |
a6f00298 | 47 | CGROUP_SUBSYS_COUNT, |
817929ec PM |
48 | }; |
49 | #undef SUBSYS | |
50 | ||
5c9d535b TH |
51 | /* |
52 | * Per-subsystem/per-cgroup state maintained by the system. This is the | |
53 | * fundamental structural building block that controllers deal with. | |
54 | * | |
55 | * Fields marked with "PI:" are public and immutable and may be accessed | |
56 | * directly without synchronization. | |
57 | */ | |
ddbcc7e8 | 58 | struct cgroup_subsys_state { |
5c9d535b | 59 | /* PI: the cgroup that this css is attached to */ |
ddbcc7e8 PM |
60 | struct cgroup *cgroup; |
61 | ||
5c9d535b | 62 | /* PI: the cgroup subsystem that this css is attached to */ |
72c97e54 TH |
63 | struct cgroup_subsys *ss; |
64 | ||
d3daf28d TH |
65 | /* reference count - access via css_[try]get() and css_put() */ |
66 | struct percpu_ref refcnt; | |
ddbcc7e8 | 67 | |
5c9d535b | 68 | /* PI: the parent css */ |
0ae78e0b TH |
69 | struct cgroup_subsys_state *parent; |
70 | ||
d5c419b6 TH |
71 | /* siblings list anchored at the parent's ->children */ |
72 | struct list_head sibling; | |
73 | struct list_head children; | |
74 | ||
15a4c835 | 75 | /* |
5c9d535b | 76 | * PI: Subsys-unique ID. 0 is unused and root is always 1. The |
15a4c835 TH |
77 | * matching css can be looked up using css_from_id(). |
78 | */ | |
79 | int id; | |
80 | ||
69dfa00c | 81 | unsigned int flags; |
48ddbe19 | 82 | |
0cb51d71 TH |
83 | /* |
84 | * Monotonically increasing unique serial number which defines a | |
85 | * uniform order among all csses. It's guaranteed that all | |
86 | * ->children lists are in the ascending order of ->serial_nr and | |
87 | * used to allow interrupting and resuming iterations. | |
88 | */ | |
89 | u64 serial_nr; | |
90 | ||
0c21ead1 TH |
91 | /* percpu_ref killing and RCU release */ |
92 | struct rcu_head rcu_head; | |
35ef10da | 93 | struct work_struct destroy_work; |
ddbcc7e8 PM |
94 | }; |
95 | ||
96 | /* bits in struct cgroup_subsys_state flags field */ | |
97 | enum { | |
3b514d24 | 98 | CSS_NO_REF = (1 << 0), /* no reference counting for this css */ |
92fb9748 | 99 | CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ |
de3f0341 | 100 | CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */ |
ddbcc7e8 PM |
101 | }; |
102 | ||
5de0107e TH |
103 | /** |
104 | * css_get - obtain a reference on the specified css | |
105 | * @css: target css | |
106 | * | |
107 | * The caller must already have a reference. | |
ddbcc7e8 | 108 | */ |
ddbcc7e8 PM |
109 | static inline void css_get(struct cgroup_subsys_state *css) |
110 | { | |
3b514d24 TH |
111 | if (!(css->flags & CSS_NO_REF)) |
112 | percpu_ref_get(&css->refcnt); | |
ddbcc7e8 | 113 | } |
e7c5ec91 | 114 | |
6f4524d3 TH |
115 | /** |
116 | * css_tryget - try to obtain a reference on the specified css | |
117 | * @css: target css | |
118 | * | |
119 | * Obtain a reference on @css unless it already has reached zero and is | |
120 | * being released. This function doesn't care whether @css is on or | |
121 | * offline. The caller naturally needs to ensure that @css is accessible | |
122 | * but doesn't have to be holding a reference on it - IOW, RCU protected | |
123 | * access is good enough for this function. Returns %true if a reference | |
124 | * count was successfully obtained; %false otherwise. | |
125 | */ | |
126 | static inline bool css_tryget(struct cgroup_subsys_state *css) | |
127 | { | |
128 | if (!(css->flags & CSS_NO_REF)) | |
129 | return percpu_ref_tryget(&css->refcnt); | |
130 | return true; | |
131 | } | |
132 | ||
5de0107e | 133 | /** |
ec903c0c | 134 | * css_tryget_online - try to obtain a reference on the specified css if online |
5de0107e TH |
135 | * @css: target css |
136 | * | |
ec903c0c TH |
137 | * Obtain a reference on @css if it's online. The caller naturally needs |
138 | * to ensure that @css is accessible but doesn't have to be holding a | |
5de0107e TH |
139 | * reference on it - IOW, RCU protected access is good enough for this |
140 | * function. Returns %true if a reference count was successfully obtained; | |
141 | * %false otherwise. | |
142 | */ | |
ec903c0c | 143 | static inline bool css_tryget_online(struct cgroup_subsys_state *css) |
e7c5ec91 | 144 | { |
3b514d24 TH |
145 | if (!(css->flags & CSS_NO_REF)) |
146 | return percpu_ref_tryget_live(&css->refcnt); | |
147 | return true; | |
e7c5ec91 PM |
148 | } |
149 | ||
5de0107e TH |
150 | /** |
151 | * css_put - put a css reference | |
152 | * @css: target css | |
153 | * | |
ec903c0c | 154 | * Put a reference obtained via css_get() and css_tryget_online(). |
5de0107e | 155 | */ |
ddbcc7e8 PM |
156 | static inline void css_put(struct cgroup_subsys_state *css) |
157 | { | |
3b514d24 TH |
158 | if (!(css->flags & CSS_NO_REF)) |
159 | percpu_ref_put(&css->refcnt); | |
ddbcc7e8 PM |
160 | } |
161 | ||
3116f0e3 PM |
162 | /* bits in struct cgroup flags field */ |
163 | enum { | |
d20a390a PM |
164 | /* |
165 | * Control Group has previously had a child cgroup or a task, | |
166 | * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) | |
167 | */ | |
3116f0e3 PM |
168 | CGRP_RELEASABLE, |
169 | /* Control Group requires release notifications to userspace */ | |
170 | CGRP_NOTIFY_ON_RELEASE, | |
97978e6d | 171 | /* |
2260e7fc TH |
172 | * Clone the parent's configuration when creating a new child |
173 | * cpuset cgroup. For historical reasons, this option can be | |
174 | * specified at mount time and thus is implemented here. | |
97978e6d | 175 | */ |
2260e7fc | 176 | CGRP_CPUSET_CLONE_CHILDREN, |
3116f0e3 PM |
177 | }; |
178 | ||
ddbcc7e8 | 179 | struct cgroup { |
9d800df1 TH |
180 | /* self css with NULL ->ss, points back to this cgroup */ |
181 | struct cgroup_subsys_state self; | |
182 | ||
ddbcc7e8 PM |
183 | unsigned long flags; /* "unsigned long" so bitops work */ |
184 | ||
b414dc09 LZ |
185 | /* |
186 | * idr allocated in-hierarchy ID. | |
187 | * | |
7d699ddb TH |
188 | * ID 0 is not used, the ID of the root cgroup is always 1, and a |
189 | * new cgroup will be assigned with a smallest available ID. | |
0ab02ca8 LZ |
190 | * |
191 | * Allocating/Removing ID must be protected by cgroup_mutex. | |
b414dc09 LZ |
192 | */ |
193 | int id; | |
0a950f65 | 194 | |
842b597e TH |
195 | /* |
196 | * If this cgroup contains any tasks, it contributes one to | |
197 | * populated_cnt. All children with non-zero popuplated_cnt of | |
198 | * their own contribute one. The count is zero iff there's no task | |
199 | * in this cgroup or its subtree. | |
200 | */ | |
201 | int populated_cnt; | |
202 | ||
2bd59d48 | 203 | struct kernfs_node *kn; /* cgroup kernfs entry */ |
842b597e | 204 | struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */ |
ddbcc7e8 | 205 | |
f392e51c | 206 | /* the bitmask of subsystems enabled on the child cgroups */ |
69dfa00c | 207 | unsigned int child_subsys_mask; |
94419627 | 208 | |
ddbcc7e8 | 209 | /* Private pointers for each registered subsystem */ |
73e80ed8 | 210 | struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT]; |
ddbcc7e8 | 211 | |
3dd06ffa | 212 | struct cgroup_root *root; |
817929ec PM |
213 | |
214 | /* | |
69d0206c TH |
215 | * List of cgrp_cset_links pointing at css_sets with tasks in this |
216 | * cgroup. Protected by css_set_lock. | |
817929ec | 217 | */ |
69d0206c | 218 | struct list_head cset_links; |
81a6a5cd | 219 | |
2d8f243a TH |
220 | /* |
221 | * On the default hierarchy, a css_set for a cgroup with some | |
222 | * susbsys disabled will point to css's which are associated with | |
223 | * the closest ancestor which has the subsys enabled. The | |
224 | * following lists all css_sets which point to this cgroup's css | |
225 | * for the given subsystem. | |
226 | */ | |
227 | struct list_head e_csets[CGROUP_SUBSYS_COUNT]; | |
228 | ||
81a6a5cd PM |
229 | /* |
230 | * Linked list running through all cgroups that can | |
231 | * potentially be reaped by the release agent. Protected by | |
232 | * release_list_lock | |
233 | */ | |
234 | struct list_head release_list; | |
cc31edce | 235 | |
72a8cb30 BB |
236 | /* |
237 | * list of pidlists, up to two for each namespace (one for procs, one | |
238 | * for tasks); created on demand. | |
239 | */ | |
240 | struct list_head pidlists; | |
241 | struct mutex pidlist_mutex; | |
a47295e6 | 242 | |
f8f22e53 TH |
243 | /* used to wait for offlining of csses */ |
244 | wait_queue_head_t offline_waitq; | |
817929ec PM |
245 | }; |
246 | ||
25a7e684 TH |
247 | #define MAX_CGROUP_ROOT_NAMELEN 64 |
248 | ||
3dd06ffa | 249 | /* cgroup_root->flags */ |
25a7e684 | 250 | enum { |
873fe09e TH |
251 | /* |
252 | * Unfortunately, cgroup core and various controllers are riddled | |
253 | * with idiosyncrasies and pointless options. The following flag, | |
254 | * when set, will force sane behavior - some options are forced on, | |
255 | * others are disallowed, and some controllers will change their | |
256 | * hierarchical or other behaviors. | |
257 | * | |
258 | * The set of behaviors affected by this flag are still being | |
259 | * determined and developed and the mount option for this flag is | |
260 | * prefixed with __DEVEL__. The prefix will be dropped once we | |
261 | * reach the point where all behaviors are compatible with the | |
262 | * planned unified hierarchy, which will automatically turn on this | |
263 | * flag. | |
264 | * | |
265 | * The followings are the behaviors currently affected this flag. | |
266 | * | |
d3ba07c3 TH |
267 | * - Mount options "noprefix", "xattr", "clone_children", |
268 | * "release_agent" and "name" are disallowed. | |
873fe09e TH |
269 | * |
270 | * - When mounting an existing superblock, mount options should | |
271 | * match. | |
272 | * | |
273 | * - Remount is disallowed. | |
274 | * | |
0b0585c3 LT |
275 | * - rename(2) is disallowed. |
276 | * | |
f63674fd TH |
277 | * - "tasks" is removed. Everything should be at process |
278 | * granularity. Use "cgroup.procs" instead. | |
f00baae7 | 279 | * |
afb2bc14 TH |
280 | * - "cgroup.procs" is not sorted. pids will be unique unless they |
281 | * got recycled inbetween reads. | |
282 | * | |
f63674fd TH |
283 | * - "release_agent" and "notify_on_release" are removed. |
284 | * Replacement notification mechanism will be implemented. | |
873fe09e | 285 | * |
d3ba07c3 | 286 | * - "cgroup.clone_children" is removed. |
86bf4b68 | 287 | * |
842b597e TH |
288 | * - "cgroup.subtree_populated" is available. Its value is 0 if |
289 | * the cgroup and its descendants contain no task; otherwise, 1. | |
290 | * The file also generates kernfs notification which can be | |
291 | * monitored through poll and [di]notify when the value of the | |
292 | * file changes. | |
293 | * | |
a2dd4247 TH |
294 | * - If mount is requested with sane_behavior but without any |
295 | * subsystem, the default unified hierarchy is mounted. | |
296 | * | |
5c5cc623 LZ |
297 | * - cpuset: tasks will be kept in empty cpusets when hotplug happens |
298 | * and take masks of ancestors with non-empty cpus/mems, instead of | |
299 | * being moved to an ancestor. | |
300 | * | |
88fa523b LZ |
301 | * - cpuset: a task can be moved into an empty cpuset, and again it |
302 | * takes masks of ancestors. | |
6db8e85c | 303 | * |
f63674fd TH |
304 | * - memcg: use_hierarchy is on by default and the cgroup file for |
305 | * the flag is not created. | |
f00baae7 | 306 | * |
9138125b | 307 | * - blkcg: blk-throttle becomes properly hierarchical. |
873fe09e TH |
308 | */ |
309 | CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), | |
310 | ||
25a7e684 TH |
311 | CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ |
312 | CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ | |
0ce6cba3 TH |
313 | |
314 | /* mount options live below bit 16 */ | |
315 | CGRP_ROOT_OPTION_MASK = (1 << 16) - 1, | |
25a7e684 TH |
316 | }; |
317 | ||
318 | /* | |
3dd06ffa | 319 | * A cgroup_root represents the root of a cgroup hierarchy, and may be |
2bd59d48 | 320 | * associated with a kernfs_root to form an active hierarchy. This is |
25a7e684 TH |
321 | * internal to cgroup core. Don't access directly from controllers. |
322 | */ | |
3dd06ffa | 323 | struct cgroup_root { |
2bd59d48 | 324 | struct kernfs_root *kf_root; |
25a7e684 | 325 | |
f392e51c | 326 | /* The bitmask of subsystems attached to this hierarchy */ |
69dfa00c | 327 | unsigned int subsys_mask; |
f392e51c | 328 | |
25a7e684 TH |
329 | /* Unique id for this hierarchy. */ |
330 | int hierarchy_id; | |
331 | ||
776f02fa | 332 | /* The root cgroup. Root is destroyed on its release. */ |
3dd06ffa | 333 | struct cgroup cgrp; |
25a7e684 | 334 | |
3c9c825b TH |
335 | /* Number of cgroups in the hierarchy, used only for /proc/cgroups */ |
336 | atomic_t nr_cgrps; | |
25a7e684 TH |
337 | |
338 | /* A list running through the active hierarchies */ | |
339 | struct list_head root_list; | |
340 | ||
25a7e684 | 341 | /* Hierarchy-specific flags */ |
69dfa00c | 342 | unsigned int flags; |
25a7e684 TH |
343 | |
344 | /* IDs for cgroups in this hierarchy */ | |
4e96ee8e | 345 | struct idr cgroup_idr; |
25a7e684 TH |
346 | |
347 | /* The path to use for release notifications. */ | |
348 | char release_agent_path[PATH_MAX]; | |
349 | ||
350 | /* The name for this hierarchy - may be empty */ | |
351 | char name[MAX_CGROUP_ROOT_NAMELEN]; | |
352 | }; | |
353 | ||
d20a390a PM |
354 | /* |
355 | * A css_set is a structure holding pointers to a set of | |
817929ec PM |
356 | * cgroup_subsys_state objects. This saves space in the task struct |
357 | * object and speeds up fork()/exit(), since a single inc/dec and a | |
d20a390a PM |
358 | * list_add()/del() can bump the reference count on the entire cgroup |
359 | * set for a task. | |
817929ec PM |
360 | */ |
361 | ||
362 | struct css_set { | |
363 | ||
364 | /* Reference count */ | |
146aa1bd | 365 | atomic_t refcount; |
817929ec | 366 | |
472b1053 LZ |
367 | /* |
368 | * List running through all cgroup groups in the same hash | |
369 | * slot. Protected by css_set_lock | |
370 | */ | |
371 | struct hlist_node hlist; | |
372 | ||
817929ec | 373 | /* |
c7561128 TH |
374 | * Lists running through all tasks using this cgroup group. |
375 | * mg_tasks lists tasks which belong to this cset but are in the | |
376 | * process of being migrated out or in. Protected by | |
377 | * css_set_rwsem, but, during migration, once tasks are moved to | |
378 | * mg_tasks, it can be read safely while holding cgroup_mutex. | |
817929ec PM |
379 | */ |
380 | struct list_head tasks; | |
c7561128 | 381 | struct list_head mg_tasks; |
817929ec PM |
382 | |
383 | /* | |
69d0206c TH |
384 | * List of cgrp_cset_links pointing at cgroups referenced from this |
385 | * css_set. Protected by css_set_lock. | |
817929ec | 386 | */ |
69d0206c | 387 | struct list_head cgrp_links; |
817929ec | 388 | |
6803c006 TH |
389 | /* the default cgroup associated with this css_set */ |
390 | struct cgroup *dfl_cgrp; | |
391 | ||
817929ec | 392 | /* |
3ed80a62 TH |
393 | * Set of subsystem states, one for each subsystem. This array is |
394 | * immutable after creation apart from the init_css_set during | |
395 | * subsystem registration (at boot time). | |
817929ec PM |
396 | */ |
397 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; | |
c378369d | 398 | |
b3dc094e TH |
399 | /* |
400 | * List of csets participating in the on-going migration either as | |
401 | * source or destination. Protected by cgroup_mutex. | |
402 | */ | |
1958d2d5 | 403 | struct list_head mg_preload_node; |
b3dc094e TH |
404 | struct list_head mg_node; |
405 | ||
406 | /* | |
407 | * If this cset is acting as the source of migration the following | |
408 | * two fields are set. mg_src_cgrp is the source cgroup of the | |
409 | * on-going migration and mg_dst_cset is the destination cset the | |
410 | * target tasks on this cset should be migrated to. Protected by | |
411 | * cgroup_mutex. | |
412 | */ | |
413 | struct cgroup *mg_src_cgrp; | |
414 | struct css_set *mg_dst_cset; | |
415 | ||
2d8f243a TH |
416 | /* |
417 | * On the default hierarhcy, ->subsys[ssid] may point to a css | |
418 | * attached to an ancestor instead of the cgroup this css_set is | |
419 | * associated with. The following node is anchored at | |
420 | * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to | |
421 | * iterate through all css's attached to a given cgroup. | |
422 | */ | |
423 | struct list_head e_cset_node[CGROUP_SUBSYS_COUNT]; | |
424 | ||
c378369d BB |
425 | /* For RCU-protected deletion */ |
426 | struct rcu_head rcu_head; | |
ddbcc7e8 PM |
427 | }; |
428 | ||
d20a390a PM |
429 | /* |
430 | * struct cftype: handler definitions for cgroup control files | |
ddbcc7e8 PM |
431 | * |
432 | * When reading/writing to a file: | |
a043e3b2 | 433 | * - the cgroup to use is file->f_dentry->d_parent->d_fsdata |
ddbcc7e8 PM |
434 | * - the 'cftype' of the file is file->f_dentry->d_fsdata |
435 | */ | |
436 | ||
8e3f6541 | 437 | /* cftype->flags */ |
02c402d9 | 438 | enum { |
6f4b7e63 LZ |
439 | CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */ |
440 | CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */ | |
02c402d9 | 441 | CFTYPE_INSANE = (1 << 2), /* don't create if sane_behavior */ |
9fa4db33 | 442 | CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ |
8cbbf2c9 | 443 | CFTYPE_ONLY_ON_DFL = (1 << 4), /* only on default hierarchy */ |
02c402d9 | 444 | }; |
8e3f6541 TH |
445 | |
446 | #define MAX_CFTYPE_NAME 64 | |
447 | ||
ddbcc7e8 | 448 | struct cftype { |
d20a390a PM |
449 | /* |
450 | * By convention, the name should begin with the name of the | |
8e3f6541 TH |
451 | * subsystem, followed by a period. Zero length string indicates |
452 | * end of cftype array. | |
d20a390a | 453 | */ |
ddbcc7e8 PM |
454 | char name[MAX_CFTYPE_NAME]; |
455 | int private; | |
099fca32 LZ |
456 | /* |
457 | * If not 0, file mode is set to this value, otherwise it will | |
458 | * be figured out automatically | |
459 | */ | |
a5e7ed32 | 460 | umode_t mode; |
db3b1497 PM |
461 | |
462 | /* | |
5f469907 | 463 | * The maximum length of string, excluding trailing nul, that can |
451af504 | 464 | * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed. |
db3b1497 PM |
465 | */ |
466 | size_t max_write_len; | |
467 | ||
8e3f6541 TH |
468 | /* CFTYPE_* flags */ |
469 | unsigned int flags; | |
470 | ||
2bb566cb | 471 | /* |
0adb0704 TH |
472 | * Fields used for internal bookkeeping. Initialized automatically |
473 | * during registration. | |
2bb566cb | 474 | */ |
0adb0704 TH |
475 | struct cgroup_subsys *ss; /* NULL for cgroup core files */ |
476 | struct list_head node; /* anchored at ss->cfts */ | |
2bd59d48 TH |
477 | struct kernfs_ops *kf_ops; |
478 | ||
ddbcc7e8 | 479 | /* |
f4c753b7 | 480 | * read_u64() is a shortcut for the common case of returning a |
ddbcc7e8 PM |
481 | * single integer. Use it in place of read() |
482 | */ | |
182446d0 | 483 | u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft); |
e73d2c61 PM |
484 | /* |
485 | * read_s64() is a signed version of read_u64() | |
486 | */ | |
182446d0 | 487 | s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); |
2da8ca82 TH |
488 | |
489 | /* generic seq_file read interface */ | |
490 | int (*seq_show)(struct seq_file *sf, void *v); | |
91796569 | 491 | |
6612f05b TH |
492 | /* optional ops, implement all or none */ |
493 | void *(*seq_start)(struct seq_file *sf, loff_t *ppos); | |
494 | void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); | |
495 | void (*seq_stop)(struct seq_file *sf, void *v); | |
496 | ||
355e0c48 | 497 | /* |
f4c753b7 | 498 | * write_u64() is a shortcut for the common case of accepting |
355e0c48 PM |
499 | * a single integer (as parsed by simple_strtoull) from |
500 | * userspace. Use in place of write(); return 0 or error. | |
501 | */ | |
182446d0 TH |
502 | int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft, |
503 | u64 val); | |
e73d2c61 PM |
504 | /* |
505 | * write_s64() is a signed version of write_u64() | |
506 | */ | |
182446d0 TH |
507 | int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft, |
508 | s64 val); | |
355e0c48 | 509 | |
b4168640 TH |
510 | /* |
511 | * write() is the generic write callback which maps directly to | |
512 | * kernfs write operation and overrides all other operations. | |
513 | * Maximum write size is determined by ->max_write_len. Use | |
514 | * of_css/cft() to access the associated css and cft. | |
515 | */ | |
516 | ssize_t (*write)(struct kernfs_open_file *of, | |
517 | char *buf, size_t nbytes, loff_t off); | |
518 | ||
2bd59d48 TH |
519 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
520 | struct lock_class_key lockdep_key; | |
521 | #endif | |
ddbcc7e8 PM |
522 | }; |
523 | ||
a2dd4247 | 524 | extern struct cgroup_root cgrp_dfl_root; |
5024ae29 | 525 | extern struct css_set init_css_set; |
a2dd4247 TH |
526 | |
527 | static inline bool cgroup_on_dfl(const struct cgroup *cgrp) | |
528 | { | |
529 | return cgrp->root == &cgrp_dfl_root; | |
530 | } | |
531 | ||
873fe09e TH |
532 | /* |
533 | * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This | |
534 | * function can be called as long as @cgrp is accessible. | |
535 | */ | |
536 | static inline bool cgroup_sane_behavior(const struct cgroup *cgrp) | |
537 | { | |
538 | return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR; | |
539 | } | |
540 | ||
07bc356e TH |
541 | /* no synchronization, the result can only be used as a hint */ |
542 | static inline bool cgroup_has_tasks(struct cgroup *cgrp) | |
543 | { | |
544 | return !list_empty(&cgrp->cset_links); | |
545 | } | |
546 | ||
b1664924 TH |
547 | /* returns ino associated with a cgroup, 0 indicates unmounted root */ |
548 | static inline ino_t cgroup_ino(struct cgroup *cgrp) | |
549 | { | |
2bd59d48 TH |
550 | if (cgrp->kn) |
551 | return cgrp->kn->ino; | |
b1664924 TH |
552 | else |
553 | return 0; | |
554 | } | |
555 | ||
b4168640 TH |
556 | /* cft/css accessors for cftype->write() operation */ |
557 | static inline struct cftype *of_cft(struct kernfs_open_file *of) | |
7da11279 | 558 | { |
2bd59d48 | 559 | return of->kn->priv; |
7da11279 TH |
560 | } |
561 | ||
b4168640 TH |
562 | struct cgroup_subsys_state *of_css(struct kernfs_open_file *of); |
563 | ||
564 | /* cft/css accessors for cftype->seq_*() operations */ | |
565 | static inline struct cftype *seq_cft(struct seq_file *seq) | |
566 | { | |
567 | return of_cft(seq->private); | |
568 | } | |
569 | ||
570 | static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq) | |
571 | { | |
572 | return of_css(seq->private); | |
573 | } | |
59f5296b | 574 | |
e61734c5 TH |
575 | /* |
576 | * Name / path handling functions. All are thin wrappers around the kernfs | |
577 | * counterparts and can be called under any context. | |
578 | */ | |
579 | ||
580 | static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen) | |
581 | { | |
fdce6bf8 | 582 | return kernfs_name(cgrp->kn, buf, buflen); |
e61734c5 TH |
583 | } |
584 | ||
585 | static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf, | |
586 | size_t buflen) | |
587 | { | |
fdce6bf8 | 588 | return kernfs_path(cgrp->kn, buf, buflen); |
e61734c5 TH |
589 | } |
590 | ||
591 | static inline void pr_cont_cgroup_name(struct cgroup *cgrp) | |
592 | { | |
fdce6bf8 | 593 | pr_cont_kernfs_name(cgrp->kn); |
e61734c5 TH |
594 | } |
595 | ||
596 | static inline void pr_cont_cgroup_path(struct cgroup *cgrp) | |
597 | { | |
fdce6bf8 | 598 | pr_cont_kernfs_path(cgrp->kn); |
e61734c5 TH |
599 | } |
600 | ||
601 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen); | |
602 | ||
03b1cde6 | 603 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); |
2bb566cb | 604 | int cgroup_rm_cftypes(struct cftype *cfts); |
8e3f6541 | 605 | |
78574cf9 | 606 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor); |
ddbcc7e8 | 607 | |
2f7ee569 TH |
608 | /* |
609 | * Control Group taskset, used to pass around set of tasks to cgroup_subsys | |
610 | * methods. | |
611 | */ | |
612 | struct cgroup_taskset; | |
613 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset); | |
614 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset); | |
2f7ee569 TH |
615 | |
616 | /** | |
617 | * cgroup_taskset_for_each - iterate cgroup_taskset | |
618 | * @task: the loop cursor | |
2f7ee569 TH |
619 | * @tset: taskset to iterate |
620 | */ | |
924f0d9a | 621 | #define cgroup_taskset_for_each(task, tset) \ |
2f7ee569 | 622 | for ((task) = cgroup_taskset_first((tset)); (task); \ |
924f0d9a | 623 | (task) = cgroup_taskset_next((tset))) |
2f7ee569 | 624 | |
21acb9ca TLSC |
625 | /* |
626 | * Control Group subsystem type. | |
627 | * See Documentation/cgroups/cgroups.txt for details | |
628 | */ | |
ddbcc7e8 PM |
629 | |
630 | struct cgroup_subsys { | |
eb95419b TH |
631 | struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css); |
632 | int (*css_online)(struct cgroup_subsys_state *css); | |
633 | void (*css_offline)(struct cgroup_subsys_state *css); | |
634 | void (*css_free)(struct cgroup_subsys_state *css); | |
635 | ||
636 | int (*can_attach)(struct cgroup_subsys_state *css, | |
637 | struct cgroup_taskset *tset); | |
638 | void (*cancel_attach)(struct cgroup_subsys_state *css, | |
639 | struct cgroup_taskset *tset); | |
640 | void (*attach)(struct cgroup_subsys_state *css, | |
641 | struct cgroup_taskset *tset); | |
761b3ef5 | 642 | void (*fork)(struct task_struct *task); |
eb95419b TH |
643 | void (*exit)(struct cgroup_subsys_state *css, |
644 | struct cgroup_subsys_state *old_css, | |
761b3ef5 | 645 | struct task_struct *task); |
eb95419b | 646 | void (*bind)(struct cgroup_subsys_state *root_css); |
e5991371 | 647 | |
8bab8dde | 648 | int disabled; |
ddbcc7e8 | 649 | int early_init; |
48ddbe19 | 650 | |
8c7f6edb TH |
651 | /* |
652 | * If %false, this subsystem is properly hierarchical - | |
653 | * configuration, resource accounting and restriction on a parent | |
654 | * cgroup cover those of its children. If %true, hierarchy support | |
655 | * is broken in some ways - some subsystems ignore hierarchy | |
656 | * completely while others are only implemented half-way. | |
657 | * | |
658 | * It's now disallowed to create nested cgroups if the subsystem is | |
659 | * broken and cgroup core will emit a warning message on such | |
660 | * cases. Eventually, all subsystems will be made properly | |
661 | * hierarchical and this will go away. | |
662 | */ | |
663 | bool broken_hierarchy; | |
664 | bool warned_broken_hierarchy; | |
665 | ||
073219e9 | 666 | /* the following two fields are initialized automtically during boot */ |
aec25020 | 667 | int id; |
ddbcc7e8 PM |
668 | #define MAX_CGROUP_TYPE_NAMELEN 32 |
669 | const char *name; | |
670 | ||
b85d2040 | 671 | /* link to parent, protected by cgroup_lock() */ |
3dd06ffa | 672 | struct cgroup_root *root; |
e6a1105b | 673 | |
15a4c835 TH |
674 | /* idr for css->id */ |
675 | struct idr css_idr; | |
676 | ||
0adb0704 TH |
677 | /* |
678 | * List of cftypes. Each entry is the first entry of an array | |
679 | * terminated by zero length name. | |
680 | */ | |
681 | struct list_head cfts; | |
8e3f6541 | 682 | |
de00ffa5 | 683 | /* base cftypes, automatically registered with subsys itself */ |
8e3f6541 | 684 | struct cftype *base_cftypes; |
ddbcc7e8 PM |
685 | }; |
686 | ||
073219e9 | 687 | #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys; |
ddbcc7e8 PM |
688 | #include <linux/cgroup_subsys.h> |
689 | #undef SUBSYS | |
690 | ||
14611e51 TH |
691 | /** |
692 | * task_css_set_check - obtain a task's css_set with extra access conditions | |
693 | * @task: the task to obtain css_set for | |
694 | * @__c: extra condition expression to be passed to rcu_dereference_check() | |
695 | * | |
696 | * A task's css_set is RCU protected, initialized and exited while holding | |
697 | * task_lock(), and can only be modified while holding both cgroup_mutex | |
698 | * and task_lock() while the task is alive. This macro verifies that the | |
699 | * caller is inside proper critical section and returns @task's css_set. | |
700 | * | |
701 | * The caller can also specify additional allowed conditions via @__c, such | |
702 | * as locks used during the cgroup_subsys::attach() methods. | |
dc61b1d6 | 703 | */ |
2219449a TH |
704 | #ifdef CONFIG_PROVE_RCU |
705 | extern struct mutex cgroup_mutex; | |
0e1d768f | 706 | extern struct rw_semaphore css_set_rwsem; |
14611e51 TH |
707 | #define task_css_set_check(task, __c) \ |
708 | rcu_dereference_check((task)->cgroups, \ | |
0e1d768f TH |
709 | lockdep_is_held(&cgroup_mutex) || \ |
710 | lockdep_is_held(&css_set_rwsem) || \ | |
711 | ((task)->flags & PF_EXITING) || (__c)) | |
2219449a | 712 | #else |
14611e51 TH |
713 | #define task_css_set_check(task, __c) \ |
714 | rcu_dereference((task)->cgroups) | |
2219449a | 715 | #endif |
dc61b1d6 | 716 | |
14611e51 | 717 | /** |
8af01f56 | 718 | * task_css_check - obtain css for (task, subsys) w/ extra access conds |
14611e51 TH |
719 | * @task: the target task |
720 | * @subsys_id: the target subsystem ID | |
721 | * @__c: extra condition expression to be passed to rcu_dereference_check() | |
722 | * | |
723 | * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The | |
724 | * synchronization rules are the same as task_css_set_check(). | |
725 | */ | |
8af01f56 | 726 | #define task_css_check(task, subsys_id, __c) \ |
14611e51 TH |
727 | task_css_set_check((task), (__c))->subsys[(subsys_id)] |
728 | ||
729 | /** | |
730 | * task_css_set - obtain a task's css_set | |
731 | * @task: the task to obtain css_set for | |
732 | * | |
733 | * See task_css_set_check(). | |
734 | */ | |
735 | static inline struct css_set *task_css_set(struct task_struct *task) | |
736 | { | |
737 | return task_css_set_check(task, false); | |
738 | } | |
739 | ||
740 | /** | |
8af01f56 | 741 | * task_css - obtain css for (task, subsys) |
14611e51 TH |
742 | * @task: the target task |
743 | * @subsys_id: the target subsystem ID | |
744 | * | |
8af01f56 | 745 | * See task_css_check(). |
14611e51 | 746 | */ |
8af01f56 TH |
747 | static inline struct cgroup_subsys_state *task_css(struct task_struct *task, |
748 | int subsys_id) | |
ddbcc7e8 | 749 | { |
8af01f56 | 750 | return task_css_check(task, subsys_id, false); |
ddbcc7e8 PM |
751 | } |
752 | ||
5024ae29 TH |
753 | /** |
754 | * task_css_is_root - test whether a task belongs to the root css | |
755 | * @task: the target task | |
756 | * @subsys_id: the target subsystem ID | |
757 | * | |
758 | * Test whether @task belongs to the root css on the specified subsystem. | |
759 | * May be invoked in any context. | |
760 | */ | |
761 | static inline bool task_css_is_root(struct task_struct *task, int subsys_id) | |
762 | { | |
763 | return task_css_check(task, subsys_id, true) == | |
764 | init_css_set.subsys[subsys_id]; | |
765 | } | |
766 | ||
8af01f56 TH |
767 | static inline struct cgroup *task_cgroup(struct task_struct *task, |
768 | int subsys_id) | |
ddbcc7e8 | 769 | { |
8af01f56 | 770 | return task_css(task, subsys_id)->cgroup; |
ddbcc7e8 PM |
771 | } |
772 | ||
492eb21b TH |
773 | struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
774 | struct cgroup_subsys_state *parent); | |
53fa5261 | 775 | |
1cb650b9 LZ |
776 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss); |
777 | ||
574bd9f7 | 778 | /** |
492eb21b TH |
779 | * css_for_each_child - iterate through children of a css |
780 | * @pos: the css * to use as the loop cursor | |
781 | * @parent: css whose children to walk | |
574bd9f7 | 782 | * |
c2931b70 | 783 | * Walk @parent's children. Must be called under rcu_read_lock(). |
574bd9f7 | 784 | * |
c2931b70 TH |
785 | * If a subsystem synchronizes ->css_online() and the start of iteration, a |
786 | * css which finished ->css_online() is guaranteed to be visible in the | |
787 | * future iterations and will stay visible until the last reference is put. | |
788 | * A css which hasn't finished ->css_online() or already finished | |
789 | * ->css_offline() may show up during traversal. It's each subsystem's | |
790 | * responsibility to synchronize against on/offlining. | |
75501a6d TH |
791 | * |
792 | * It is allowed to temporarily drop RCU read lock during iteration. The | |
793 | * caller is responsible for ensuring that @pos remains accessible until | |
794 | * the start of the next iteration by, for example, bumping the css refcnt. | |
574bd9f7 | 795 | */ |
492eb21b TH |
796 | #define css_for_each_child(pos, parent) \ |
797 | for ((pos) = css_next_child(NULL, (parent)); (pos); \ | |
798 | (pos) = css_next_child((pos), (parent))) | |
574bd9f7 | 799 | |
492eb21b TH |
800 | struct cgroup_subsys_state * |
801 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
802 | struct cgroup_subsys_state *css); | |
803 | ||
804 | struct cgroup_subsys_state * | |
805 | css_rightmost_descendant(struct cgroup_subsys_state *pos); | |
574bd9f7 TH |
806 | |
807 | /** | |
492eb21b TH |
808 | * css_for_each_descendant_pre - pre-order walk of a css's descendants |
809 | * @pos: the css * to use as the loop cursor | |
810 | * @root: css whose descendants to walk | |
574bd9f7 | 811 | * |
bd8815a6 | 812 | * Walk @root's descendants. @root is included in the iteration and the |
c2931b70 | 813 | * first node to be visited. Must be called under rcu_read_lock(). |
574bd9f7 | 814 | * |
c2931b70 TH |
815 | * If a subsystem synchronizes ->css_online() and the start of iteration, a |
816 | * css which finished ->css_online() is guaranteed to be visible in the | |
817 | * future iterations and will stay visible until the last reference is put. | |
818 | * A css which hasn't finished ->css_online() or already finished | |
819 | * ->css_offline() may show up during traversal. It's each subsystem's | |
820 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 821 | * |
c2931b70 | 822 | * For example, the following guarantees that a descendant can't escape |
574bd9f7 TH |
823 | * state updates of its ancestors. |
824 | * | |
492eb21b | 825 | * my_online(@css) |
574bd9f7 | 826 | * { |
492eb21b TH |
827 | * Lock @css's parent and @css; |
828 | * Inherit state from the parent; | |
574bd9f7 TH |
829 | * Unlock both. |
830 | * } | |
831 | * | |
492eb21b | 832 | * my_update_state(@css) |
574bd9f7 | 833 | * { |
492eb21b | 834 | * css_for_each_descendant_pre(@pos, @css) { |
574bd9f7 | 835 | * Lock @pos; |
bd8815a6 TH |
836 | * if (@pos == @css) |
837 | * Update @css's state; | |
838 | * else | |
839 | * Verify @pos is alive and inherit state from its parent; | |
574bd9f7 TH |
840 | * Unlock @pos; |
841 | * } | |
842 | * } | |
843 | * | |
844 | * As long as the inheriting step, including checking the parent state, is | |
845 | * enclosed inside @pos locking, double-locking the parent isn't necessary | |
846 | * while inheriting. The state update to the parent is guaranteed to be | |
847 | * visible by walking order and, as long as inheriting operations to the | |
848 | * same @pos are atomic to each other, multiple updates racing each other | |
849 | * still result in the correct state. It's guaranateed that at least one | |
492eb21b | 850 | * inheritance happens for any css after the latest update to its parent. |
574bd9f7 TH |
851 | * |
852 | * If checking parent's state requires locking the parent, each inheriting | |
853 | * iteration should lock and unlock both @pos->parent and @pos. | |
854 | * | |
855 | * Alternatively, a subsystem may choose to use a single global lock to | |
92fb9748 | 856 | * synchronize ->css_online() and ->css_offline() against tree-walking |
574bd9f7 | 857 | * operations. |
75501a6d TH |
858 | * |
859 | * It is allowed to temporarily drop RCU read lock during iteration. The | |
860 | * caller is responsible for ensuring that @pos remains accessible until | |
861 | * the start of the next iteration by, for example, bumping the css refcnt. | |
574bd9f7 | 862 | */ |
492eb21b TH |
863 | #define css_for_each_descendant_pre(pos, css) \ |
864 | for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \ | |
865 | (pos) = css_next_descendant_pre((pos), (css))) | |
574bd9f7 | 866 | |
492eb21b TH |
867 | struct cgroup_subsys_state * |
868 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
869 | struct cgroup_subsys_state *css); | |
574bd9f7 TH |
870 | |
871 | /** | |
492eb21b TH |
872 | * css_for_each_descendant_post - post-order walk of a css's descendants |
873 | * @pos: the css * to use as the loop cursor | |
874 | * @css: css whose descendants to walk | |
574bd9f7 | 875 | * |
492eb21b | 876 | * Similar to css_for_each_descendant_pre() but performs post-order |
bd8815a6 | 877 | * traversal instead. @root is included in the iteration and the last |
c2931b70 TH |
878 | * node to be visited. |
879 | * | |
880 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
881 | * css which finished ->css_online() is guaranteed to be visible in the | |
882 | * future iterations and will stay visible until the last reference is put. | |
883 | * A css which hasn't finished ->css_online() or already finished | |
884 | * ->css_offline() may show up during traversal. It's each subsystem's | |
885 | * responsibility to synchronize against on/offlining. | |
886 | * | |
887 | * Note that the walk visibility guarantee example described in pre-order | |
888 | * walk doesn't apply the same to post-order walks. | |
574bd9f7 | 889 | */ |
492eb21b TH |
890 | #define css_for_each_descendant_post(pos, css) \ |
891 | for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \ | |
892 | (pos) = css_next_descendant_post((pos), (css))) | |
574bd9f7 | 893 | |
f3d46500 TH |
894 | bool css_has_online_children(struct cgroup_subsys_state *css); |
895 | ||
72ec7029 TH |
896 | /* A css_task_iter should be treated as an opaque object */ |
897 | struct css_task_iter { | |
3ebb2b6e TH |
898 | struct cgroup_subsys *ss; |
899 | ||
0f0a2b4f TH |
900 | struct list_head *cset_pos; |
901 | struct list_head *cset_head; | |
902 | ||
903 | struct list_head *task_pos; | |
904 | struct list_head *tasks_head; | |
905 | struct list_head *mg_tasks_head; | |
817929ec PM |
906 | }; |
907 | ||
72ec7029 TH |
908 | void css_task_iter_start(struct cgroup_subsys_state *css, |
909 | struct css_task_iter *it); | |
910 | struct task_struct *css_task_iter_next(struct css_task_iter *it); | |
911 | void css_task_iter_end(struct css_task_iter *it); | |
e535837b | 912 | |
31583bb0 | 913 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); |
8cc99345 | 914 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); |
31583bb0 | 915 | |
ec903c0c TH |
916 | struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
917 | struct cgroup_subsys *ss); | |
38460b48 | 918 | |
ddbcc7e8 PM |
919 | #else /* !CONFIG_CGROUPS */ |
920 | ||
921 | static inline int cgroup_init_early(void) { return 0; } | |
922 | static inline int cgroup_init(void) { return 0; } | |
b4f48b63 | 923 | static inline void cgroup_fork(struct task_struct *p) {} |
817929ec | 924 | static inline void cgroup_post_fork(struct task_struct *p) {} |
1ec41830 | 925 | static inline void cgroup_exit(struct task_struct *p) {} |
ddbcc7e8 | 926 | |
846c7bb0 BS |
927 | static inline int cgroupstats_build(struct cgroupstats *stats, |
928 | struct dentry *dentry) | |
929 | { | |
930 | return -EINVAL; | |
931 | } | |
ddbcc7e8 | 932 | |
d7926ee3 | 933 | /* No cgroups - nothing to do */ |
31583bb0 MT |
934 | static inline int cgroup_attach_task_all(struct task_struct *from, |
935 | struct task_struct *t) | |
936 | { | |
937 | return 0; | |
938 | } | |
d7926ee3 | 939 | |
ddbcc7e8 PM |
940 | #endif /* !CONFIG_CGROUPS */ |
941 | ||
942 | #endif /* _LINUX_CGROUP_H */ |