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b4a04ab7 TH |
1 | /* |
2 | * linux/cgroup-defs.h - basic definitions for cgroup | |
3 | * | |
4 | * This file provides basic type and interface. Include this file directly | |
5 | * only if necessary to avoid cyclic dependencies. | |
6 | */ | |
7 | #ifndef _LINUX_CGROUP_DEFS_H | |
8 | #define _LINUX_CGROUP_DEFS_H | |
9 | ||
10 | #include <linux/limits.h> | |
11 | #include <linux/list.h> | |
12 | #include <linux/idr.h> | |
13 | #include <linux/wait.h> | |
14 | #include <linux/mutex.h> | |
15 | #include <linux/rcupdate.h> | |
16 | #include <linux/percpu-refcount.h> | |
7d7efec3 | 17 | #include <linux/percpu-rwsem.h> |
b4a04ab7 TH |
18 | #include <linux/workqueue.h> |
19 | ||
20 | #ifdef CONFIG_CGROUPS | |
21 | ||
22 | struct cgroup; | |
23 | struct cgroup_root; | |
24 | struct cgroup_subsys; | |
25 | struct cgroup_taskset; | |
26 | struct kernfs_node; | |
27 | struct kernfs_ops; | |
28 | struct kernfs_open_file; | |
c80ef9e0 | 29 | struct seq_file; |
b4a04ab7 TH |
30 | |
31 | #define MAX_CGROUP_TYPE_NAMELEN 32 | |
32 | #define MAX_CGROUP_ROOT_NAMELEN 64 | |
33 | #define MAX_CFTYPE_NAME 64 | |
34 | ||
35 | /* define the enumeration of all cgroup subsystems */ | |
36 | #define SUBSYS(_x) _x ## _cgrp_id, | |
7e47682e AS |
37 | #define SUBSYS_TAG(_t) CGROUP_ ## _t, \ |
38 | __unused_tag_ ## _t = CGROUP_ ## _t - 1, | |
b4a04ab7 TH |
39 | enum cgroup_subsys_id { |
40 | #include <linux/cgroup_subsys.h> | |
41 | CGROUP_SUBSYS_COUNT, | |
42 | }; | |
7e47682e | 43 | #undef SUBSYS_TAG |
b4a04ab7 TH |
44 | #undef SUBSYS |
45 | ||
7e47682e AS |
46 | #define CGROUP_CANFORK_COUNT (CGROUP_CANFORK_END - CGROUP_CANFORK_START) |
47 | ||
b4a04ab7 TH |
48 | /* bits in struct cgroup_subsys_state flags field */ |
49 | enum { | |
50 | CSS_NO_REF = (1 << 0), /* no reference counting for this css */ | |
51 | CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ | |
52 | CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */ | |
53 | }; | |
54 | ||
55 | /* bits in struct cgroup flags field */ | |
56 | enum { | |
57 | /* Control Group requires release notifications to userspace */ | |
58 | CGRP_NOTIFY_ON_RELEASE, | |
59 | /* | |
60 | * Clone the parent's configuration when creating a new child | |
61 | * cpuset cgroup. For historical reasons, this option can be | |
62 | * specified at mount time and thus is implemented here. | |
63 | */ | |
64 | CGRP_CPUSET_CLONE_CHILDREN, | |
65 | }; | |
66 | ||
67 | /* cgroup_root->flags */ | |
68 | enum { | |
b4a04ab7 TH |
69 | CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ |
70 | CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ | |
71 | }; | |
72 | ||
73 | /* cftype->flags */ | |
74 | enum { | |
75 | CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */ | |
76 | CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */ | |
77 | CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ | |
7dbdb199 | 78 | CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */ |
b4a04ab7 TH |
79 | |
80 | /* internal flags, do not use outside cgroup core proper */ | |
81 | __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ | |
82 | __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */ | |
83 | }; | |
84 | ||
6f60eade TH |
85 | /* |
86 | * cgroup_file is the handle for a file instance created in a cgroup which | |
87 | * is used, for example, to generate file changed notifications. This can | |
88 | * be obtained by setting cftype->file_offset. | |
89 | */ | |
90 | struct cgroup_file { | |
91 | /* do not access any fields from outside cgroup core */ | |
6f60eade TH |
92 | struct kernfs_node *kn; |
93 | }; | |
94 | ||
b4a04ab7 TH |
95 | /* |
96 | * Per-subsystem/per-cgroup state maintained by the system. This is the | |
97 | * fundamental structural building block that controllers deal with. | |
98 | * | |
99 | * Fields marked with "PI:" are public and immutable and may be accessed | |
100 | * directly without synchronization. | |
101 | */ | |
102 | struct cgroup_subsys_state { | |
103 | /* PI: the cgroup that this css is attached to */ | |
104 | struct cgroup *cgroup; | |
105 | ||
106 | /* PI: the cgroup subsystem that this css is attached to */ | |
107 | struct cgroup_subsys *ss; | |
108 | ||
109 | /* reference count - access via css_[try]get() and css_put() */ | |
110 | struct percpu_ref refcnt; | |
111 | ||
112 | /* PI: the parent css */ | |
113 | struct cgroup_subsys_state *parent; | |
114 | ||
115 | /* siblings list anchored at the parent's ->children */ | |
116 | struct list_head sibling; | |
117 | struct list_head children; | |
118 | ||
119 | /* | |
120 | * PI: Subsys-unique ID. 0 is unused and root is always 1. The | |
121 | * matching css can be looked up using css_from_id(). | |
122 | */ | |
123 | int id; | |
124 | ||
125 | unsigned int flags; | |
126 | ||
127 | /* | |
128 | * Monotonically increasing unique serial number which defines a | |
129 | * uniform order among all csses. It's guaranteed that all | |
130 | * ->children lists are in the ascending order of ->serial_nr and | |
131 | * used to allow interrupting and resuming iterations. | |
132 | */ | |
133 | u64 serial_nr; | |
134 | ||
135 | /* percpu_ref killing and RCU release */ | |
136 | struct rcu_head rcu_head; | |
137 | struct work_struct destroy_work; | |
138 | }; | |
139 | ||
140 | /* | |
141 | * A css_set is a structure holding pointers to a set of | |
142 | * cgroup_subsys_state objects. This saves space in the task struct | |
143 | * object and speeds up fork()/exit(), since a single inc/dec and a | |
144 | * list_add()/del() can bump the reference count on the entire cgroup | |
145 | * set for a task. | |
146 | */ | |
147 | struct css_set { | |
148 | /* Reference count */ | |
149 | atomic_t refcount; | |
150 | ||
151 | /* | |
152 | * List running through all cgroup groups in the same hash | |
153 | * slot. Protected by css_set_lock | |
154 | */ | |
155 | struct hlist_node hlist; | |
156 | ||
157 | /* | |
158 | * Lists running through all tasks using this cgroup group. | |
159 | * mg_tasks lists tasks which belong to this cset but are in the | |
160 | * process of being migrated out or in. Protected by | |
161 | * css_set_rwsem, but, during migration, once tasks are moved to | |
162 | * mg_tasks, it can be read safely while holding cgroup_mutex. | |
163 | */ | |
164 | struct list_head tasks; | |
165 | struct list_head mg_tasks; | |
166 | ||
167 | /* | |
168 | * List of cgrp_cset_links pointing at cgroups referenced from this | |
169 | * css_set. Protected by css_set_lock. | |
170 | */ | |
171 | struct list_head cgrp_links; | |
172 | ||
173 | /* the default cgroup associated with this css_set */ | |
174 | struct cgroup *dfl_cgrp; | |
175 | ||
176 | /* | |
177 | * Set of subsystem states, one for each subsystem. This array is | |
178 | * immutable after creation apart from the init_css_set during | |
179 | * subsystem registration (at boot time). | |
180 | */ | |
181 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; | |
182 | ||
183 | /* | |
184 | * List of csets participating in the on-going migration either as | |
185 | * source or destination. Protected by cgroup_mutex. | |
186 | */ | |
187 | struct list_head mg_preload_node; | |
188 | struct list_head mg_node; | |
189 | ||
190 | /* | |
191 | * If this cset is acting as the source of migration the following | |
192 | * two fields are set. mg_src_cgrp is the source cgroup of the | |
193 | * on-going migration and mg_dst_cset is the destination cset the | |
194 | * target tasks on this cset should be migrated to. Protected by | |
195 | * cgroup_mutex. | |
196 | */ | |
197 | struct cgroup *mg_src_cgrp; | |
198 | struct css_set *mg_dst_cset; | |
199 | ||
200 | /* | |
201 | * On the default hierarhcy, ->subsys[ssid] may point to a css | |
202 | * attached to an ancestor instead of the cgroup this css_set is | |
203 | * associated with. The following node is anchored at | |
204 | * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to | |
205 | * iterate through all css's attached to a given cgroup. | |
206 | */ | |
207 | struct list_head e_cset_node[CGROUP_SUBSYS_COUNT]; | |
208 | ||
ed27b9f7 TH |
209 | /* all css_task_iters currently walking this cset */ |
210 | struct list_head task_iters; | |
211 | ||
b4a04ab7 TH |
212 | /* For RCU-protected deletion */ |
213 | struct rcu_head rcu_head; | |
214 | }; | |
215 | ||
216 | struct cgroup { | |
217 | /* self css with NULL ->ss, points back to this cgroup */ | |
218 | struct cgroup_subsys_state self; | |
219 | ||
220 | unsigned long flags; /* "unsigned long" so bitops work */ | |
221 | ||
222 | /* | |
223 | * idr allocated in-hierarchy ID. | |
224 | * | |
225 | * ID 0 is not used, the ID of the root cgroup is always 1, and a | |
226 | * new cgroup will be assigned with a smallest available ID. | |
227 | * | |
228 | * Allocating/Removing ID must be protected by cgroup_mutex. | |
229 | */ | |
230 | int id; | |
231 | ||
232 | /* | |
0de0942d TH |
233 | * Each non-empty css_set associated with this cgroup contributes |
234 | * one to populated_cnt. All children with non-zero popuplated_cnt | |
235 | * of their own contribute one. The count is zero iff there's no | |
236 | * task in this cgroup or its subtree. | |
b4a04ab7 TH |
237 | */ |
238 | int populated_cnt; | |
239 | ||
240 | struct kernfs_node *kn; /* cgroup kernfs entry */ | |
6f60eade TH |
241 | struct cgroup_file procs_file; /* handle for "cgroup.procs" */ |
242 | struct cgroup_file events_file; /* handle for "cgroup.events" */ | |
b4a04ab7 TH |
243 | |
244 | /* | |
245 | * The bitmask of subsystems enabled on the child cgroups. | |
246 | * ->subtree_control is the one configured through | |
247 | * "cgroup.subtree_control" while ->child_subsys_mask is the | |
248 | * effective one which may have more subsystems enabled. | |
249 | * Controller knobs are made available iff it's enabled in | |
250 | * ->subtree_control. | |
251 | */ | |
252 | unsigned int subtree_control; | |
253 | unsigned int child_subsys_mask; | |
254 | ||
255 | /* Private pointers for each registered subsystem */ | |
256 | struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT]; | |
257 | ||
258 | struct cgroup_root *root; | |
259 | ||
260 | /* | |
261 | * List of cgrp_cset_links pointing at css_sets with tasks in this | |
262 | * cgroup. Protected by css_set_lock. | |
263 | */ | |
264 | struct list_head cset_links; | |
265 | ||
266 | /* | |
267 | * On the default hierarchy, a css_set for a cgroup with some | |
268 | * susbsys disabled will point to css's which are associated with | |
269 | * the closest ancestor which has the subsys enabled. The | |
270 | * following lists all css_sets which point to this cgroup's css | |
271 | * for the given subsystem. | |
272 | */ | |
273 | struct list_head e_csets[CGROUP_SUBSYS_COUNT]; | |
274 | ||
275 | /* | |
276 | * list of pidlists, up to two for each namespace (one for procs, one | |
277 | * for tasks); created on demand. | |
278 | */ | |
279 | struct list_head pidlists; | |
280 | struct mutex pidlist_mutex; | |
281 | ||
282 | /* used to wait for offlining of csses */ | |
283 | wait_queue_head_t offline_waitq; | |
284 | ||
285 | /* used to schedule release agent */ | |
286 | struct work_struct release_agent_work; | |
287 | }; | |
288 | ||
289 | /* | |
290 | * A cgroup_root represents the root of a cgroup hierarchy, and may be | |
291 | * associated with a kernfs_root to form an active hierarchy. This is | |
292 | * internal to cgroup core. Don't access directly from controllers. | |
293 | */ | |
294 | struct cgroup_root { | |
295 | struct kernfs_root *kf_root; | |
296 | ||
297 | /* The bitmask of subsystems attached to this hierarchy */ | |
298 | unsigned int subsys_mask; | |
299 | ||
300 | /* Unique id for this hierarchy. */ | |
301 | int hierarchy_id; | |
302 | ||
303 | /* The root cgroup. Root is destroyed on its release. */ | |
304 | struct cgroup cgrp; | |
305 | ||
306 | /* Number of cgroups in the hierarchy, used only for /proc/cgroups */ | |
307 | atomic_t nr_cgrps; | |
308 | ||
309 | /* A list running through the active hierarchies */ | |
310 | struct list_head root_list; | |
311 | ||
312 | /* Hierarchy-specific flags */ | |
313 | unsigned int flags; | |
314 | ||
315 | /* IDs for cgroups in this hierarchy */ | |
316 | struct idr cgroup_idr; | |
317 | ||
318 | /* The path to use for release notifications. */ | |
319 | char release_agent_path[PATH_MAX]; | |
320 | ||
321 | /* The name for this hierarchy - may be empty */ | |
322 | char name[MAX_CGROUP_ROOT_NAMELEN]; | |
323 | }; | |
324 | ||
325 | /* | |
326 | * struct cftype: handler definitions for cgroup control files | |
327 | * | |
328 | * When reading/writing to a file: | |
329 | * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata | |
330 | * - the 'cftype' of the file is file->f_path.dentry->d_fsdata | |
331 | */ | |
332 | struct cftype { | |
333 | /* | |
334 | * By convention, the name should begin with the name of the | |
335 | * subsystem, followed by a period. Zero length string indicates | |
336 | * end of cftype array. | |
337 | */ | |
338 | char name[MAX_CFTYPE_NAME]; | |
731a981e | 339 | unsigned long private; |
b4a04ab7 TH |
340 | |
341 | /* | |
342 | * The maximum length of string, excluding trailing nul, that can | |
343 | * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed. | |
344 | */ | |
345 | size_t max_write_len; | |
346 | ||
347 | /* CFTYPE_* flags */ | |
348 | unsigned int flags; | |
349 | ||
6f60eade TH |
350 | /* |
351 | * If non-zero, should contain the offset from the start of css to | |
352 | * a struct cgroup_file field. cgroup will record the handle of | |
353 | * the created file into it. The recorded handle can be used as | |
354 | * long as the containing css remains accessible. | |
355 | */ | |
356 | unsigned int file_offset; | |
357 | ||
b4a04ab7 TH |
358 | /* |
359 | * Fields used for internal bookkeeping. Initialized automatically | |
360 | * during registration. | |
361 | */ | |
362 | struct cgroup_subsys *ss; /* NULL for cgroup core files */ | |
363 | struct list_head node; /* anchored at ss->cfts */ | |
364 | struct kernfs_ops *kf_ops; | |
365 | ||
366 | /* | |
367 | * read_u64() is a shortcut for the common case of returning a | |
368 | * single integer. Use it in place of read() | |
369 | */ | |
370 | u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft); | |
371 | /* | |
372 | * read_s64() is a signed version of read_u64() | |
373 | */ | |
374 | s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); | |
375 | ||
376 | /* generic seq_file read interface */ | |
377 | int (*seq_show)(struct seq_file *sf, void *v); | |
378 | ||
379 | /* optional ops, implement all or none */ | |
380 | void *(*seq_start)(struct seq_file *sf, loff_t *ppos); | |
381 | void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); | |
382 | void (*seq_stop)(struct seq_file *sf, void *v); | |
383 | ||
384 | /* | |
385 | * write_u64() is a shortcut for the common case of accepting | |
386 | * a single integer (as parsed by simple_strtoull) from | |
387 | * userspace. Use in place of write(); return 0 or error. | |
388 | */ | |
389 | int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft, | |
390 | u64 val); | |
391 | /* | |
392 | * write_s64() is a signed version of write_u64() | |
393 | */ | |
394 | int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft, | |
395 | s64 val); | |
396 | ||
397 | /* | |
398 | * write() is the generic write callback which maps directly to | |
399 | * kernfs write operation and overrides all other operations. | |
400 | * Maximum write size is determined by ->max_write_len. Use | |
401 | * of_css/cft() to access the associated css and cft. | |
402 | */ | |
403 | ssize_t (*write)(struct kernfs_open_file *of, | |
404 | char *buf, size_t nbytes, loff_t off); | |
405 | ||
406 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
407 | struct lock_class_key lockdep_key; | |
408 | #endif | |
409 | }; | |
410 | ||
411 | /* | |
412 | * Control Group subsystem type. | |
413 | * See Documentation/cgroups/cgroups.txt for details | |
414 | */ | |
415 | struct cgroup_subsys { | |
416 | struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css); | |
417 | int (*css_online)(struct cgroup_subsys_state *css); | |
418 | void (*css_offline)(struct cgroup_subsys_state *css); | |
419 | void (*css_released)(struct cgroup_subsys_state *css); | |
420 | void (*css_free)(struct cgroup_subsys_state *css); | |
421 | void (*css_reset)(struct cgroup_subsys_state *css); | |
422 | void (*css_e_css_changed)(struct cgroup_subsys_state *css); | |
423 | ||
1f7dd3e5 TH |
424 | int (*can_attach)(struct cgroup_taskset *tset); |
425 | void (*cancel_attach)(struct cgroup_taskset *tset); | |
426 | void (*attach)(struct cgroup_taskset *tset); | |
7e47682e AS |
427 | int (*can_fork)(struct task_struct *task, void **priv_p); |
428 | void (*cancel_fork)(struct task_struct *task, void *priv); | |
429 | void (*fork)(struct task_struct *task, void *priv); | |
2e91fa7f | 430 | void (*exit)(struct task_struct *task); |
afcf6c8b | 431 | void (*free)(struct task_struct *task); |
b4a04ab7 TH |
432 | void (*bind)(struct cgroup_subsys_state *root_css); |
433 | ||
b4a04ab7 TH |
434 | int early_init; |
435 | ||
436 | /* | |
437 | * If %false, this subsystem is properly hierarchical - | |
438 | * configuration, resource accounting and restriction on a parent | |
439 | * cgroup cover those of its children. If %true, hierarchy support | |
440 | * is broken in some ways - some subsystems ignore hierarchy | |
441 | * completely while others are only implemented half-way. | |
442 | * | |
443 | * It's now disallowed to create nested cgroups if the subsystem is | |
444 | * broken and cgroup core will emit a warning message on such | |
445 | * cases. Eventually, all subsystems will be made properly | |
446 | * hierarchical and this will go away. | |
447 | */ | |
448 | bool broken_hierarchy; | |
449 | bool warned_broken_hierarchy; | |
450 | ||
451 | /* the following two fields are initialized automtically during boot */ | |
452 | int id; | |
453 | const char *name; | |
454 | ||
3e1d2eed TH |
455 | /* optional, initialized automatically during boot if not set */ |
456 | const char *legacy_name; | |
457 | ||
b4a04ab7 TH |
458 | /* link to parent, protected by cgroup_lock() */ |
459 | struct cgroup_root *root; | |
460 | ||
461 | /* idr for css->id */ | |
462 | struct idr css_idr; | |
463 | ||
464 | /* | |
465 | * List of cftypes. Each entry is the first entry of an array | |
466 | * terminated by zero length name. | |
467 | */ | |
468 | struct list_head cfts; | |
469 | ||
470 | /* | |
471 | * Base cftypes which are automatically registered. The two can | |
472 | * point to the same array. | |
473 | */ | |
474 | struct cftype *dfl_cftypes; /* for the default hierarchy */ | |
475 | struct cftype *legacy_cftypes; /* for the legacy hierarchies */ | |
476 | ||
477 | /* | |
478 | * A subsystem may depend on other subsystems. When such subsystem | |
479 | * is enabled on a cgroup, the depended-upon subsystems are enabled | |
480 | * together if available. Subsystems enabled due to dependency are | |
481 | * not visible to userland until explicitly enabled. The following | |
482 | * specifies the mask of subsystems that this one depends on. | |
483 | */ | |
484 | unsigned int depends_on; | |
485 | }; | |
486 | ||
1ed13287 TH |
487 | extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
488 | ||
489 | /** | |
490 | * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups | |
491 | * @tsk: target task | |
492 | * | |
493 | * Called from threadgroup_change_begin() and allows cgroup operations to | |
494 | * synchronize against threadgroup changes using a percpu_rw_semaphore. | |
495 | */ | |
496 | static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) | |
497 | { | |
498 | percpu_down_read(&cgroup_threadgroup_rwsem); | |
499 | } | |
500 | ||
501 | /** | |
502 | * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups | |
503 | * @tsk: target task | |
504 | * | |
505 | * Called from threadgroup_change_end(). Counterpart of | |
506 | * cgroup_threadcgroup_change_begin(). | |
507 | */ | |
508 | static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) | |
509 | { | |
510 | percpu_up_read(&cgroup_threadgroup_rwsem); | |
511 | } | |
7d7efec3 TH |
512 | |
513 | #else /* CONFIG_CGROUPS */ | |
514 | ||
7e47682e | 515 | #define CGROUP_CANFORK_COUNT 0 |
cb4a3167 AS |
516 | #define CGROUP_SUBSYS_COUNT 0 |
517 | ||
7d7efec3 TH |
518 | static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {} |
519 | static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {} | |
520 | ||
b4a04ab7 | 521 | #endif /* CONFIG_CGROUPS */ |
7d7efec3 | 522 | |
b4a04ab7 | 523 | #endif /* _LINUX_CGROUP_DEFS_H */ |