cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offli...
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / include / linux / cgroup.h
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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>
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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>
31a7df01 17#include <linux/prio_heap.h>
cc31edce 18#include <linux/rwsem.h>
38460b48 19#include <linux/idr.h>
48ddbe19 20#include <linux/workqueue.h>
03b1cde6 21#include <linux/xattr.h>
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22
23#ifdef CONFIG_CGROUPS
24
25struct cgroupfs_root;
26struct cgroup_subsys;
27struct inode;
84eea842 28struct cgroup;
38460b48 29struct css_id;
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30
31extern int cgroup_init_early(void);
32extern int cgroup_init(void);
ddbcc7e8 33extern void cgroup_lock(void);
d11c563d 34extern int cgroup_lock_is_held(void);
84eea842 35extern bool cgroup_lock_live_group(struct cgroup *cgrp);
ddbcc7e8 36extern void cgroup_unlock(void);
b4f48b63 37extern void cgroup_fork(struct task_struct *p);
817929ec 38extern void cgroup_post_fork(struct task_struct *p);
b4f48b63 39extern void cgroup_exit(struct task_struct *p, int run_callbacks);
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40extern int cgroupstats_build(struct cgroupstats *stats,
41 struct dentry *dentry);
e6a1105b 42extern int cgroup_load_subsys(struct cgroup_subsys *ss);
cf5d5941 43extern void cgroup_unload_subsys(struct cgroup_subsys *ss);
ddbcc7e8 44
828c0950 45extern const struct file_operations proc_cgroup_operations;
a424316c 46
aae8aab4 47/* Define the enumeration of all builtin cgroup subsystems */
817929ec 48#define SUBSYS(_x) _x ## _subsys_id,
8a8e04df 49#define IS_SUBSYS_ENABLED(option) IS_ENABLED(option)
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50enum cgroup_subsys_id {
51#include <linux/cgroup_subsys.h>
a6f00298 52 CGROUP_SUBSYS_COUNT,
817929ec 53};
5fc0b025 54#undef IS_SUBSYS_ENABLED
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55#undef SUBSYS
56
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57/* Per-subsystem/per-cgroup state maintained by the system. */
58struct cgroup_subsys_state {
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59 /*
60 * The cgroup that this subsystem is attached to. Useful
ddbcc7e8 61 * for subsystems that want to know about the cgroup
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62 * hierarchy structure
63 */
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64 struct cgroup *cgroup;
65
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66 /*
67 * State maintained by the cgroup system to allow subsystems
e7c5ec91 68 * to be "busy". Should be accessed via css_get(),
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69 * css_tryget() and and css_put().
70 */
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71
72 atomic_t refcnt;
73
74 unsigned long flags;
38460b48 75 /* ID for this css, if possible */
2c392b8c 76 struct css_id __rcu *id;
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77
78 /* Used to put @cgroup->dentry on the last css_put() */
79 struct work_struct dput_work;
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80};
81
82/* bits in struct cgroup_subsys_state flags field */
83enum {
38b53aba 84 CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */
92fb9748 85 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
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86};
87
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88/* Caller must verify that the css is not for root cgroup */
89static inline void __css_get(struct cgroup_subsys_state *css, int count)
90{
91 atomic_add(count, &css->refcnt);
92}
93
ddbcc7e8 94/*
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95 * Call css_get() to hold a reference on the css; it can be used
96 * for a reference obtained via:
97 * - an existing ref-counted reference to the css
98 * - task->cgroups for a locked task
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99 */
100
101static inline void css_get(struct cgroup_subsys_state *css)
102{
103 /* We don't need to reference count the root state */
38b53aba 104 if (!(css->flags & CSS_ROOT))
d7b9fff7 105 __css_get(css, 1);
ddbcc7e8 106}
e7c5ec91 107
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108/*
109 * Call css_tryget() to take a reference on a css if your existing
110 * (known-valid) reference isn't already ref-counted. Returns false if
111 * the css has been destroyed.
112 */
113
28b4c27b 114extern bool __css_tryget(struct cgroup_subsys_state *css);
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115static inline bool css_tryget(struct cgroup_subsys_state *css)
116{
38b53aba 117 if (css->flags & CSS_ROOT)
e7c5ec91 118 return true;
28b4c27b 119 return __css_tryget(css);
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120}
121
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122/*
123 * css_put() should be called to release a reference taken by
e7c5ec91 124 * css_get() or css_tryget()
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125 */
126
28b4c27b 127extern void __css_put(struct cgroup_subsys_state *css);
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128static inline void css_put(struct cgroup_subsys_state *css)
129{
38b53aba 130 if (!(css->flags & CSS_ROOT))
28b4c27b 131 __css_put(css);
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132}
133
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134/* bits in struct cgroup flags field */
135enum {
136 /* Control Group is dead */
137 CGRP_REMOVED,
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138 /*
139 * Control Group has previously had a child cgroup or a task,
140 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
141 */
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142 CGRP_RELEASABLE,
143 /* Control Group requires release notifications to userspace */
144 CGRP_NOTIFY_ON_RELEASE,
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145 /*
146 * Clone cgroup values when creating a new child cgroup
147 */
148 CGRP_CLONE_CHILDREN,
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149};
150
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151struct cgroup {
152 unsigned long flags; /* "unsigned long" so bitops work */
153
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154 /*
155 * count users of this cgroup. >0 means busy, but doesn't
156 * necessarily indicate the number of tasks in the cgroup
157 */
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158 atomic_t count;
159
160 /*
161 * We link our 'sibling' struct into our parent's 'children'.
162 * Our children link their 'sibling' into our 'children'.
163 */
164 struct list_head sibling; /* my parent's children */
165 struct list_head children; /* my children */
05ef1d7c 166 struct list_head files; /* my files */
ddbcc7e8 167
d20a390a 168 struct cgroup *parent; /* my parent */
febfcef6 169 struct dentry *dentry; /* cgroup fs entry, RCU protected */
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170
171 /* Private pointers for each registered subsystem */
172 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
173
174 struct cgroupfs_root *root;
175 struct cgroup *top_cgroup;
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176
177 /*
178 * List of cg_cgroup_links pointing at css_sets with
179 * tasks in this cgroup. Protected by css_set_lock
180 */
181 struct list_head css_sets;
81a6a5cd 182
b0ca5a84 183 struct list_head allcg_node; /* cgroupfs_root->allcg_list */
8e3f6541 184 struct list_head cft_q_node; /* used during cftype add/rm */
b0ca5a84 185
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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
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193 /*
194 * list of pidlists, up to two for each namespace (one for procs, one
195 * for tasks); created on demand.
196 */
197 struct list_head pidlists;
198 struct mutex pidlist_mutex;
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199
200 /* For RCU-protected deletion */
201 struct rcu_head rcu_head;
0dea1168 202
25985edc 203 /* List of events which userspace want to receive */
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204 struct list_head event_list;
205 spinlock_t event_list_lock;
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206
207 /* directory xattrs */
208 struct simple_xattrs xattrs;
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209};
210
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211/*
212 * A css_set is a structure holding pointers to a set of
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213 * cgroup_subsys_state objects. This saves space in the task struct
214 * object and speeds up fork()/exit(), since a single inc/dec and a
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215 * list_add()/del() can bump the reference count on the entire cgroup
216 * set for a task.
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217 */
218
219struct css_set {
220
221 /* Reference count */
146aa1bd 222 atomic_t refcount;
817929ec 223
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224 /*
225 * List running through all cgroup groups in the same hash
226 * slot. Protected by css_set_lock
227 */
228 struct hlist_node hlist;
229
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230 /*
231 * List running through all tasks using this cgroup
232 * group. Protected by css_set_lock
233 */
234 struct list_head tasks;
235
236 /*
237 * List of cg_cgroup_link objects on link chains from
238 * cgroups referenced from this css_set. Protected by
239 * css_set_lock
240 */
241 struct list_head cg_links;
242
243 /*
244 * Set of subsystem states, one for each subsystem. This array
245 * is immutable after creation apart from the init_css_set
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246 * during subsystem registration (at boot time) and modular subsystem
247 * loading/unloading.
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248 */
249 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
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250
251 /* For RCU-protected deletion */
252 struct rcu_head rcu_head;
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253};
254
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255/*
256 * cgroup_map_cb is an abstract callback API for reporting map-valued
257 * control files
258 */
259
260struct cgroup_map_cb {
261 int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value);
262 void *state;
263};
264
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265/*
266 * struct cftype: handler definitions for cgroup control files
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267 *
268 * When reading/writing to a file:
a043e3b2 269 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata
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270 * - the 'cftype' of the file is file->f_dentry->d_fsdata
271 */
272
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273/* cftype->flags */
274#define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */
275#define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create onp root cg */
276
277#define MAX_CFTYPE_NAME 64
278
ddbcc7e8 279struct cftype {
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280 /*
281 * By convention, the name should begin with the name of the
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282 * subsystem, followed by a period. Zero length string indicates
283 * end of cftype array.
d20a390a 284 */
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285 char name[MAX_CFTYPE_NAME];
286 int private;
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287 /*
288 * If not 0, file mode is set to this value, otherwise it will
289 * be figured out automatically
290 */
a5e7ed32 291 umode_t mode;
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292
293 /*
294 * If non-zero, defines the maximum length of string that can
295 * be passed to write_string; defaults to 64
296 */
297 size_t max_write_len;
298
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299 /* CFTYPE_* flags */
300 unsigned int flags;
301
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302 /* file xattrs */
303 struct simple_xattrs xattrs;
304
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305 int (*open)(struct inode *inode, struct file *file);
306 ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
307 struct file *file,
308 char __user *buf, size_t nbytes, loff_t *ppos);
ddbcc7e8 309 /*
f4c753b7 310 * read_u64() is a shortcut for the common case of returning a
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311 * single integer. Use it in place of read()
312 */
ce16b49d 313 u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft);
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314 /*
315 * read_s64() is a signed version of read_u64()
316 */
ce16b49d 317 s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft);
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318 /*
319 * read_map() is used for defining a map of key/value
320 * pairs. It should call cb->fill(cb, key, value) for each
321 * entry. The key/value pairs (and their ordering) should not
322 * change between reboots.
323 */
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324 int (*read_map)(struct cgroup *cont, struct cftype *cft,
325 struct cgroup_map_cb *cb);
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326 /*
327 * read_seq_string() is used for outputting a simple sequence
328 * using seqfile.
329 */
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330 int (*read_seq_string)(struct cgroup *cont, struct cftype *cft,
331 struct seq_file *m);
91796569 332
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333 ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft,
334 struct file *file,
335 const char __user *buf, size_t nbytes, loff_t *ppos);
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336
337 /*
f4c753b7 338 * write_u64() is a shortcut for the common case of accepting
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339 * a single integer (as parsed by simple_strtoull) from
340 * userspace. Use in place of write(); return 0 or error.
341 */
ce16b49d 342 int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val);
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343 /*
344 * write_s64() is a signed version of write_u64()
345 */
ce16b49d 346 int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val);
355e0c48 347
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348 /*
349 * write_string() is passed a nul-terminated kernelspace
350 * buffer of maximum length determined by max_write_len.
351 * Returns 0 or -ve error code.
352 */
353 int (*write_string)(struct cgroup *cgrp, struct cftype *cft,
354 const char *buffer);
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355 /*
356 * trigger() callback can be used to get some kick from the
357 * userspace, when the actual string written is not important
358 * at all. The private field can be used to determine the
359 * kick type for multiplexing.
360 */
361 int (*trigger)(struct cgroup *cgrp, unsigned int event);
362
ce16b49d 363 int (*release)(struct inode *inode, struct file *file);
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364
365 /*
366 * register_event() callback will be used to add new userspace
367 * waiter for changes related to the cftype. Implement it if
368 * you want to provide this functionality. Use eventfd_signal()
369 * on eventfd to send notification to userspace.
370 */
371 int (*register_event)(struct cgroup *cgrp, struct cftype *cft,
372 struct eventfd_ctx *eventfd, const char *args);
373 /*
374 * unregister_event() callback will be called when userspace
375 * closes the eventfd or on cgroup removing.
376 * This callback must be implemented, if you want provide
377 * notification functionality.
0dea1168 378 */
907860ed 379 void (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
0dea1168 380 struct eventfd_ctx *eventfd);
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381};
382
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383/*
384 * cftype_sets describe cftypes belonging to a subsystem and are chained at
385 * cgroup_subsys->cftsets. Each cftset points to an array of cftypes
386 * terminated by zero length name.
387 */
388struct cftype_set {
389 struct list_head node; /* chained at subsys->cftsets */
03b1cde6 390 struct cftype *cfts;
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391};
392
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393struct cgroup_scanner {
394 struct cgroup *cg;
395 int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
396 void (*process_task)(struct task_struct *p,
397 struct cgroup_scanner *scan);
398 struct ptr_heap *heap;
bd1a8ab7 399 void *data;
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400};
401
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402int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
403int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
8e3f6541 404
ffd2d883 405int cgroup_is_removed(const struct cgroup *cgrp);
ddbcc7e8 406
ffd2d883 407int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
ddbcc7e8 408
ffd2d883 409int cgroup_task_count(const struct cgroup *cgrp);
bbcb81d0 410
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411/* Return true if cgrp is a descendant of the task's cgroup */
412int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
ddbcc7e8 413
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414/*
415 * Control Group taskset, used to pass around set of tasks to cgroup_subsys
416 * methods.
417 */
418struct cgroup_taskset;
419struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
420struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
421struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset);
422int cgroup_taskset_size(struct cgroup_taskset *tset);
423
424/**
425 * cgroup_taskset_for_each - iterate cgroup_taskset
426 * @task: the loop cursor
427 * @skip_cgrp: skip if task's cgroup matches this, %NULL to iterate through all
428 * @tset: taskset to iterate
429 */
430#define cgroup_taskset_for_each(task, skip_cgrp, tset) \
431 for ((task) = cgroup_taskset_first((tset)); (task); \
432 (task) = cgroup_taskset_next((tset))) \
433 if (!(skip_cgrp) || \
434 cgroup_taskset_cur_cgroup((tset)) != (skip_cgrp))
435
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436/*
437 * Control Group subsystem type.
438 * See Documentation/cgroups/cgroups.txt for details
439 */
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440
441struct cgroup_subsys {
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442 struct cgroup_subsys_state *(*css_alloc)(struct cgroup *cgrp);
443 int (*css_online)(struct cgroup *cgrp);
444 void (*css_offline)(struct cgroup *cgrp);
445 void (*css_free)(struct cgroup *cgrp);
446
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447 int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
448 void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
449 void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
450 void (*fork)(struct task_struct *task);
451 void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp,
452 struct task_struct *task);
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453 void (*post_clone)(struct cgroup *cgrp);
454 void (*bind)(struct cgroup *root);
e5991371 455
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456 int subsys_id;
457 int active;
8bab8dde 458 int disabled;
ddbcc7e8 459 int early_init;
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460 /*
461 * True if this subsys uses ID. ID is not available before cgroup_init()
462 * (not available in early_init time.)
463 */
464 bool use_id;
48ddbe19 465
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466 /*
467 * If %false, this subsystem is properly hierarchical -
468 * configuration, resource accounting and restriction on a parent
469 * cgroup cover those of its children. If %true, hierarchy support
470 * is broken in some ways - some subsystems ignore hierarchy
471 * completely while others are only implemented half-way.
472 *
473 * It's now disallowed to create nested cgroups if the subsystem is
474 * broken and cgroup core will emit a warning message on such
475 * cases. Eventually, all subsystems will be made properly
476 * hierarchical and this will go away.
477 */
478 bool broken_hierarchy;
479 bool warned_broken_hierarchy;
480
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481#define MAX_CGROUP_TYPE_NAMELEN 32
482 const char *name;
483
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484 /*
485 * Link to parent, and list entry in parent's children.
6be96a5c 486 * Protected by cgroup_lock()
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487 */
488 struct cgroupfs_root *root;
ddbcc7e8 489 struct list_head sibling;
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490 /* used when use_id == true */
491 struct idr idr;
42aee6c4 492 spinlock_t id_lock;
e6a1105b 493
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494 /* list of cftype_sets */
495 struct list_head cftsets;
496
497 /* base cftypes, automatically [de]registered with subsys itself */
498 struct cftype *base_cftypes;
499 struct cftype_set base_cftset;
500
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501 /* should be defined only by modular subsystems */
502 struct module *module;
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503};
504
505#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
5fc0b025 506#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
ddbcc7e8 507#include <linux/cgroup_subsys.h>
5fc0b025 508#undef IS_SUBSYS_ENABLED
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509#undef SUBSYS
510
511static inline struct cgroup_subsys_state *cgroup_subsys_state(
ffd2d883 512 struct cgroup *cgrp, int subsys_id)
ddbcc7e8 513{
ffd2d883 514 return cgrp->subsys[subsys_id];
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515}
516
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517/*
518 * function to get the cgroup_subsys_state which allows for extra
519 * rcu_dereference_check() conditions, such as locks used during the
520 * cgroup_subsys::attach() methods.
521 */
522#define task_subsys_state_check(task, subsys_id, __c) \
523 rcu_dereference_check(task->cgroups->subsys[subsys_id], \
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524 lockdep_is_held(&task->alloc_lock) || \
525 cgroup_lock_is_held() || (__c))
526
527static inline struct cgroup_subsys_state *
528task_subsys_state(struct task_struct *task, int subsys_id)
ddbcc7e8 529{
dc61b1d6 530 return task_subsys_state_check(task, subsys_id, false);
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531}
532
533static inline struct cgroup* task_cgroup(struct task_struct *task,
534 int subsys_id)
535{
536 return task_subsys_state(task, subsys_id)->cgroup;
537}
538
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539/**
540 * cgroup_for_each_child - iterate through children of a cgroup
541 * @pos: the cgroup * to use as the loop cursor
542 * @cgroup: cgroup whose children to walk
543 *
544 * Walk @cgroup's children. Must be called under rcu_read_lock(). A child
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545 * cgroup which hasn't finished ->css_online() or already has finished
546 * ->css_offline() may show up during traversal and it's each subsystem's
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547 * responsibility to verify that each @pos is alive.
548 *
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549 * If a subsystem synchronizes against the parent in its ->css_online() and
550 * before starting iterating, a cgroup which finished ->css_online() is
551 * guaranteed to be visible in the future iterations.
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552 */
553#define cgroup_for_each_child(pos, cgroup) \
554 list_for_each_entry_rcu(pos, &(cgroup)->children, sibling)
555
556struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
557 struct cgroup *cgroup);
558
559/**
560 * cgroup_for_each_descendant_pre - pre-order walk of a cgroup's descendants
561 * @pos: the cgroup * to use as the loop cursor
562 * @cgroup: cgroup whose descendants to walk
563 *
564 * Walk @cgroup's descendants. Must be called under rcu_read_lock(). A
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565 * descendant cgroup which hasn't finished ->css_online() or already has
566 * finished ->css_offline() may show up during traversal and it's each
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567 * subsystem's responsibility to verify that each @pos is alive.
568 *
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569 * If a subsystem synchronizes against the parent in its ->css_online() and
570 * before starting iterating, and synchronizes against @pos on each
571 * iteration, any descendant cgroup which finished ->css_offline() is
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572 * guaranteed to be visible in the future iterations.
573 *
574 * In other words, the following guarantees that a descendant can't escape
575 * state updates of its ancestors.
576 *
92fb9748 577 * my_online(@cgrp)
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578 * {
579 * Lock @cgrp->parent and @cgrp;
580 * Inherit state from @cgrp->parent;
581 * Unlock both.
582 * }
583 *
584 * my_update_state(@cgrp)
585 * {
586 * Lock @cgrp;
587 * Update @cgrp's state;
588 * Unlock @cgrp;
589 *
590 * cgroup_for_each_descendant_pre(@pos, @cgrp) {
591 * Lock @pos;
592 * Verify @pos is alive and inherit state from @pos->parent;
593 * Unlock @pos;
594 * }
595 * }
596 *
597 * As long as the inheriting step, including checking the parent state, is
598 * enclosed inside @pos locking, double-locking the parent isn't necessary
599 * while inheriting. The state update to the parent is guaranteed to be
600 * visible by walking order and, as long as inheriting operations to the
601 * same @pos are atomic to each other, multiple updates racing each other
602 * still result in the correct state. It's guaranateed that at least one
603 * inheritance happens for any cgroup after the latest update to its
604 * parent.
605 *
606 * If checking parent's state requires locking the parent, each inheriting
607 * iteration should lock and unlock both @pos->parent and @pos.
608 *
609 * Alternatively, a subsystem may choose to use a single global lock to
92fb9748 610 * synchronize ->css_online() and ->css_offline() against tree-walking
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611 * operations.
612 */
613#define cgroup_for_each_descendant_pre(pos, cgroup) \
614 for (pos = cgroup_next_descendant_pre(NULL, (cgroup)); (pos); \
615 pos = cgroup_next_descendant_pre((pos), (cgroup)))
616
617struct cgroup *cgroup_next_descendant_post(struct cgroup *pos,
618 struct cgroup *cgroup);
619
620/**
621 * cgroup_for_each_descendant_post - post-order walk of a cgroup's descendants
622 * @pos: the cgroup * to use as the loop cursor
623 * @cgroup: cgroup whose descendants to walk
624 *
625 * Similar to cgroup_for_each_descendant_pre() but performs post-order
626 * traversal instead. Note that the walk visibility guarantee described in
627 * pre-order walk doesn't apply the same to post-order walks.
628 */
629#define cgroup_for_each_descendant_post(pos, cgroup) \
630 for (pos = cgroup_next_descendant_post(NULL, (cgroup)); (pos); \
631 pos = cgroup_next_descendant_post((pos), (cgroup)))
632
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633/* A cgroup_iter should be treated as an opaque object */
634struct cgroup_iter {
635 struct list_head *cg_link;
636 struct list_head *task;
637};
638
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639/*
640 * To iterate across the tasks in a cgroup:
817929ec 641 *
b595076a 642 * 1) call cgroup_iter_start to initialize an iterator
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643 *
644 * 2) call cgroup_iter_next() to retrieve member tasks until it
645 * returns NULL or until you want to end the iteration
646 *
647 * 3) call cgroup_iter_end() to destroy the iterator.
31a7df01 648 *
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649 * Or, call cgroup_scan_tasks() to iterate through every task in a
650 * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling
651 * the test_task() callback, but not while calling the process_task()
652 * callback.
817929ec 653 */
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654void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
655struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
817929ec 656 struct cgroup_iter *it);
ffd2d883 657void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
31a7df01 658int cgroup_scan_tasks(struct cgroup_scanner *scan);
956db3ca 659int cgroup_attach_task(struct cgroup *, struct task_struct *);
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660int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
661
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662/*
663 * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
664 * if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
665 * CSS ID is assigned at cgroup allocation (create) automatically
666 * and removed when subsys calls free_css_id() function. This is because
667 * the lifetime of cgroup_subsys_state is subsys's matter.
668 *
669 * Looking up and scanning function should be called under rcu_read_lock().
6be96a5c 670 * Taking cgroup_mutex is not necessary for following calls.
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671 * But the css returned by this routine can be "not populated yet" or "being
672 * destroyed". The caller should check css and cgroup's status.
673 */
674
675/*
676 * Typically Called at ->destroy(), or somewhere the subsys frees
677 * cgroup_subsys_state.
678 */
679void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css);
680
681/* Find a cgroup_subsys_state which has given ID */
682
683struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id);
684
685/*
686 * Get a cgroup whose id is greater than or equal to id under tree of root.
687 * Returning a cgroup_subsys_state or NULL.
688 */
689struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id,
690 struct cgroup_subsys_state *root, int *foundid);
691
692/* Returns true if root is ancestor of cg */
693bool css_is_ancestor(struct cgroup_subsys_state *cg,
0b7f569e 694 const struct cgroup_subsys_state *root);
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695
696/* Get id and depth of css */
697unsigned short css_id(struct cgroup_subsys_state *css);
698unsigned short css_depth(struct cgroup_subsys_state *css);
e5d1367f 699struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id);
38460b48 700
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701#else /* !CONFIG_CGROUPS */
702
703static inline int cgroup_init_early(void) { return 0; }
704static inline int cgroup_init(void) { return 0; }
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705static inline void cgroup_fork(struct task_struct *p) {}
706static inline void cgroup_fork_callbacks(struct task_struct *p) {}
817929ec 707static inline void cgroup_post_fork(struct task_struct *p) {}
b4f48b63 708static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
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709
710static inline void cgroup_lock(void) {}
711static inline void cgroup_unlock(void) {}
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712static inline int cgroupstats_build(struct cgroupstats *stats,
713 struct dentry *dentry)
714{
715 return -EINVAL;
716}
ddbcc7e8 717
d7926ee3 718/* No cgroups - nothing to do */
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719static inline int cgroup_attach_task_all(struct task_struct *from,
720 struct task_struct *t)
721{
722 return 0;
723}
d7926ee3 724
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725#endif /* !CONFIG_CGROUPS */
726
727#endif /* _LINUX_CGROUP_H */