| 1 | #ifndef _LINUX_CGROUP_H |
| 2 | #define _LINUX_CGROUP_H |
| 3 | /* |
| 4 | * cgroup interface |
| 5 | * |
| 6 | * Copyright (C) 2003 BULL SA |
| 7 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. |
| 8 | * |
| 9 | */ |
| 10 | |
| 11 | #include <linux/sched.h> |
| 12 | #include <linux/cpumask.h> |
| 13 | #include <linux/nodemask.h> |
| 14 | #include <linux/rcupdate.h> |
| 15 | #include <linux/cgroupstats.h> |
| 16 | #include <linux/prio_heap.h> |
| 17 | #include <linux/rwsem.h> |
| 18 | #include <linux/idr.h> |
| 19 | #include <linux/workqueue.h> |
| 20 | #include <linux/xattr.h> |
| 21 | |
| 22 | #ifdef CONFIG_CGROUPS |
| 23 | |
| 24 | struct cgroupfs_root; |
| 25 | struct cgroup_subsys; |
| 26 | struct inode; |
| 27 | struct cgroup; |
| 28 | struct css_id; |
| 29 | |
| 30 | extern int cgroup_init_early(void); |
| 31 | extern int cgroup_init(void); |
| 32 | extern void cgroup_lock(void); |
| 33 | extern int cgroup_lock_is_held(void); |
| 34 | extern bool cgroup_lock_live_group(struct cgroup *cgrp); |
| 35 | extern void cgroup_unlock(void); |
| 36 | extern void cgroup_fork(struct task_struct *p); |
| 37 | extern void cgroup_fork_callbacks(struct task_struct *p); |
| 38 | extern void cgroup_post_fork(struct task_struct *p); |
| 39 | extern void cgroup_exit(struct task_struct *p, int run_callbacks); |
| 40 | extern int cgroupstats_build(struct cgroupstats *stats, |
| 41 | struct dentry *dentry); |
| 42 | extern int cgroup_load_subsys(struct cgroup_subsys *ss); |
| 43 | extern void cgroup_unload_subsys(struct cgroup_subsys *ss); |
| 44 | |
| 45 | extern const struct file_operations proc_cgroup_operations; |
| 46 | |
| 47 | /* Define the enumeration of all builtin cgroup subsystems */ |
| 48 | #define SUBSYS(_x) _x ## _subsys_id, |
| 49 | enum cgroup_subsys_id { |
| 50 | #include <linux/cgroup_subsys.h> |
| 51 | __CGROUP_TEMPORARY_PLACEHOLDER |
| 52 | }; |
| 53 | #undef SUBSYS |
| 54 | /* |
| 55 | * This define indicates the maximum number of subsystems that can be loaded |
| 56 | * at once. We limit to this many since cgroupfs_root has subsys_bits to keep |
| 57 | * track of all of them. |
| 58 | */ |
| 59 | #define CGROUP_SUBSYS_COUNT (BITS_PER_BYTE*sizeof(unsigned long)) |
| 60 | |
| 61 | /* Per-subsystem/per-cgroup state maintained by the system. */ |
| 62 | struct cgroup_subsys_state { |
| 63 | /* |
| 64 | * The cgroup that this subsystem is attached to. Useful |
| 65 | * for subsystems that want to know about the cgroup |
| 66 | * hierarchy structure |
| 67 | */ |
| 68 | struct cgroup *cgroup; |
| 69 | |
| 70 | /* |
| 71 | * State maintained by the cgroup system to allow subsystems |
| 72 | * to be "busy". Should be accessed via css_get(), |
| 73 | * css_tryget() and and css_put(). |
| 74 | */ |
| 75 | |
| 76 | atomic_t refcnt; |
| 77 | |
| 78 | unsigned long flags; |
| 79 | /* ID for this css, if possible */ |
| 80 | struct css_id __rcu *id; |
| 81 | |
| 82 | /* Used to put @cgroup->dentry on the last css_put() */ |
| 83 | struct work_struct dput_work; |
| 84 | }; |
| 85 | |
| 86 | /* bits in struct cgroup_subsys_state flags field */ |
| 87 | enum { |
| 88 | CSS_ROOT, /* This CSS is the root of the subsystem */ |
| 89 | CSS_REMOVED, /* This CSS is dead */ |
| 90 | CSS_CLEAR_CSS_REFS, /* @ss->__DEPRECATED_clear_css_refs */ |
| 91 | }; |
| 92 | |
| 93 | /* Caller must verify that the css is not for root cgroup */ |
| 94 | static inline void __css_get(struct cgroup_subsys_state *css, int count) |
| 95 | { |
| 96 | atomic_add(count, &css->refcnt); |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * Call css_get() to hold a reference on the css; it can be used |
| 101 | * for a reference obtained via: |
| 102 | * - an existing ref-counted reference to the css |
| 103 | * - task->cgroups for a locked task |
| 104 | */ |
| 105 | |
| 106 | static inline void css_get(struct cgroup_subsys_state *css) |
| 107 | { |
| 108 | /* We don't need to reference count the root state */ |
| 109 | if (!test_bit(CSS_ROOT, &css->flags)) |
| 110 | __css_get(css, 1); |
| 111 | } |
| 112 | |
| 113 | static inline bool css_is_removed(struct cgroup_subsys_state *css) |
| 114 | { |
| 115 | return test_bit(CSS_REMOVED, &css->flags); |
| 116 | } |
| 117 | |
| 118 | /* |
| 119 | * Call css_tryget() to take a reference on a css if your existing |
| 120 | * (known-valid) reference isn't already ref-counted. Returns false if |
| 121 | * the css has been destroyed. |
| 122 | */ |
| 123 | |
| 124 | extern bool __css_tryget(struct cgroup_subsys_state *css); |
| 125 | static inline bool css_tryget(struct cgroup_subsys_state *css) |
| 126 | { |
| 127 | if (test_bit(CSS_ROOT, &css->flags)) |
| 128 | return true; |
| 129 | return __css_tryget(css); |
| 130 | } |
| 131 | |
| 132 | /* |
| 133 | * css_put() should be called to release a reference taken by |
| 134 | * css_get() or css_tryget() |
| 135 | */ |
| 136 | |
| 137 | extern void __css_put(struct cgroup_subsys_state *css); |
| 138 | static inline void css_put(struct cgroup_subsys_state *css) |
| 139 | { |
| 140 | if (!test_bit(CSS_ROOT, &css->flags)) |
| 141 | __css_put(css); |
| 142 | } |
| 143 | |
| 144 | /* bits in struct cgroup flags field */ |
| 145 | enum { |
| 146 | /* Control Group is dead */ |
| 147 | CGRP_REMOVED, |
| 148 | /* |
| 149 | * Control Group has previously had a child cgroup or a task, |
| 150 | * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) |
| 151 | */ |
| 152 | CGRP_RELEASABLE, |
| 153 | /* Control Group requires release notifications to userspace */ |
| 154 | CGRP_NOTIFY_ON_RELEASE, |
| 155 | /* |
| 156 | * A thread in rmdir() is wating for this cgroup. |
| 157 | */ |
| 158 | CGRP_WAIT_ON_RMDIR, |
| 159 | /* |
| 160 | * Clone cgroup values when creating a new child cgroup |
| 161 | */ |
| 162 | CGRP_CLONE_CHILDREN, |
| 163 | }; |
| 164 | |
| 165 | struct cgroup { |
| 166 | unsigned long flags; /* "unsigned long" so bitops work */ |
| 167 | |
| 168 | /* |
| 169 | * count users of this cgroup. >0 means busy, but doesn't |
| 170 | * necessarily indicate the number of tasks in the cgroup |
| 171 | */ |
| 172 | atomic_t count; |
| 173 | |
| 174 | /* |
| 175 | * We link our 'sibling' struct into our parent's 'children'. |
| 176 | * Our children link their 'sibling' into our 'children'. |
| 177 | */ |
| 178 | struct list_head sibling; /* my parent's children */ |
| 179 | struct list_head children; /* my children */ |
| 180 | struct list_head files; /* my files */ |
| 181 | |
| 182 | struct cgroup *parent; /* my parent */ |
| 183 | struct dentry __rcu *dentry; /* cgroup fs entry, RCU protected */ |
| 184 | |
| 185 | /* Private pointers for each registered subsystem */ |
| 186 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
| 187 | |
| 188 | struct cgroupfs_root *root; |
| 189 | struct cgroup *top_cgroup; |
| 190 | |
| 191 | /* |
| 192 | * List of cg_cgroup_links pointing at css_sets with |
| 193 | * tasks in this cgroup. Protected by css_set_lock |
| 194 | */ |
| 195 | struct list_head css_sets; |
| 196 | |
| 197 | struct list_head allcg_node; /* cgroupfs_root->allcg_list */ |
| 198 | struct list_head cft_q_node; /* used during cftype add/rm */ |
| 199 | |
| 200 | /* |
| 201 | * Linked list running through all cgroups that can |
| 202 | * potentially be reaped by the release agent. Protected by |
| 203 | * release_list_lock |
| 204 | */ |
| 205 | struct list_head release_list; |
| 206 | |
| 207 | /* |
| 208 | * list of pidlists, up to two for each namespace (one for procs, one |
| 209 | * for tasks); created on demand. |
| 210 | */ |
| 211 | struct list_head pidlists; |
| 212 | struct mutex pidlist_mutex; |
| 213 | |
| 214 | /* For RCU-protected deletion */ |
| 215 | struct rcu_head rcu_head; |
| 216 | |
| 217 | /* List of events which userspace want to receive */ |
| 218 | struct list_head event_list; |
| 219 | spinlock_t event_list_lock; |
| 220 | |
| 221 | /* directory xattrs */ |
| 222 | struct simple_xattrs xattrs; |
| 223 | }; |
| 224 | |
| 225 | /* |
| 226 | * A css_set is a structure holding pointers to a set of |
| 227 | * cgroup_subsys_state objects. This saves space in the task struct |
| 228 | * object and speeds up fork()/exit(), since a single inc/dec and a |
| 229 | * list_add()/del() can bump the reference count on the entire cgroup |
| 230 | * set for a task. |
| 231 | */ |
| 232 | |
| 233 | struct css_set { |
| 234 | |
| 235 | /* Reference count */ |
| 236 | atomic_t refcount; |
| 237 | |
| 238 | /* |
| 239 | * List running through all cgroup groups in the same hash |
| 240 | * slot. Protected by css_set_lock |
| 241 | */ |
| 242 | struct hlist_node hlist; |
| 243 | |
| 244 | /* |
| 245 | * List running through all tasks using this cgroup |
| 246 | * group. Protected by css_set_lock |
| 247 | */ |
| 248 | struct list_head tasks; |
| 249 | |
| 250 | /* |
| 251 | * List of cg_cgroup_link objects on link chains from |
| 252 | * cgroups referenced from this css_set. Protected by |
| 253 | * css_set_lock |
| 254 | */ |
| 255 | struct list_head cg_links; |
| 256 | |
| 257 | /* |
| 258 | * Set of subsystem states, one for each subsystem. This array |
| 259 | * is immutable after creation apart from the init_css_set |
| 260 | * during subsystem registration (at boot time) and modular subsystem |
| 261 | * loading/unloading. |
| 262 | */ |
| 263 | struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
| 264 | |
| 265 | /* For RCU-protected deletion */ |
| 266 | struct rcu_head rcu_head; |
| 267 | }; |
| 268 | |
| 269 | /* |
| 270 | * cgroup_map_cb is an abstract callback API for reporting map-valued |
| 271 | * control files |
| 272 | */ |
| 273 | |
| 274 | struct cgroup_map_cb { |
| 275 | int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); |
| 276 | void *state; |
| 277 | }; |
| 278 | |
| 279 | /* |
| 280 | * struct cftype: handler definitions for cgroup control files |
| 281 | * |
| 282 | * When reading/writing to a file: |
| 283 | * - the cgroup to use is file->f_dentry->d_parent->d_fsdata |
| 284 | * - the 'cftype' of the file is file->f_dentry->d_fsdata |
| 285 | */ |
| 286 | |
| 287 | /* cftype->flags */ |
| 288 | #define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */ |
| 289 | #define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create onp root cg */ |
| 290 | |
| 291 | #define MAX_CFTYPE_NAME 64 |
| 292 | |
| 293 | struct cftype { |
| 294 | /* |
| 295 | * By convention, the name should begin with the name of the |
| 296 | * subsystem, followed by a period. Zero length string indicates |
| 297 | * end of cftype array. |
| 298 | */ |
| 299 | char name[MAX_CFTYPE_NAME]; |
| 300 | int private; |
| 301 | /* |
| 302 | * If not 0, file mode is set to this value, otherwise it will |
| 303 | * be figured out automatically |
| 304 | */ |
| 305 | umode_t mode; |
| 306 | |
| 307 | /* |
| 308 | * If non-zero, defines the maximum length of string that can |
| 309 | * be passed to write_string; defaults to 64 |
| 310 | */ |
| 311 | size_t max_write_len; |
| 312 | |
| 313 | /* CFTYPE_* flags */ |
| 314 | unsigned int flags; |
| 315 | |
| 316 | /* file xattrs */ |
| 317 | struct simple_xattrs xattrs; |
| 318 | |
| 319 | int (*open)(struct inode *inode, struct file *file); |
| 320 | ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, |
| 321 | struct file *file, |
| 322 | char __user *buf, size_t nbytes, loff_t *ppos); |
| 323 | /* |
| 324 | * read_u64() is a shortcut for the common case of returning a |
| 325 | * single integer. Use it in place of read() |
| 326 | */ |
| 327 | u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft); |
| 328 | /* |
| 329 | * read_s64() is a signed version of read_u64() |
| 330 | */ |
| 331 | s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft); |
| 332 | /* |
| 333 | * read_map() is used for defining a map of key/value |
| 334 | * pairs. It should call cb->fill(cb, key, value) for each |
| 335 | * entry. The key/value pairs (and their ordering) should not |
| 336 | * change between reboots. |
| 337 | */ |
| 338 | int (*read_map)(struct cgroup *cont, struct cftype *cft, |
| 339 | struct cgroup_map_cb *cb); |
| 340 | /* |
| 341 | * read_seq_string() is used for outputting a simple sequence |
| 342 | * using seqfile. |
| 343 | */ |
| 344 | int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, |
| 345 | struct seq_file *m); |
| 346 | |
| 347 | ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, |
| 348 | struct file *file, |
| 349 | const char __user *buf, size_t nbytes, loff_t *ppos); |
| 350 | |
| 351 | /* |
| 352 | * write_u64() is a shortcut for the common case of accepting |
| 353 | * a single integer (as parsed by simple_strtoull) from |
| 354 | * userspace. Use in place of write(); return 0 or error. |
| 355 | */ |
| 356 | int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val); |
| 357 | /* |
| 358 | * write_s64() is a signed version of write_u64() |
| 359 | */ |
| 360 | int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val); |
| 361 | |
| 362 | /* |
| 363 | * write_string() is passed a nul-terminated kernelspace |
| 364 | * buffer of maximum length determined by max_write_len. |
| 365 | * Returns 0 or -ve error code. |
| 366 | */ |
| 367 | int (*write_string)(struct cgroup *cgrp, struct cftype *cft, |
| 368 | const char *buffer); |
| 369 | /* |
| 370 | * trigger() callback can be used to get some kick from the |
| 371 | * userspace, when the actual string written is not important |
| 372 | * at all. The private field can be used to determine the |
| 373 | * kick type for multiplexing. |
| 374 | */ |
| 375 | int (*trigger)(struct cgroup *cgrp, unsigned int event); |
| 376 | |
| 377 | int (*release)(struct inode *inode, struct file *file); |
| 378 | |
| 379 | /* |
| 380 | * register_event() callback will be used to add new userspace |
| 381 | * waiter for changes related to the cftype. Implement it if |
| 382 | * you want to provide this functionality. Use eventfd_signal() |
| 383 | * on eventfd to send notification to userspace. |
| 384 | */ |
| 385 | int (*register_event)(struct cgroup *cgrp, struct cftype *cft, |
| 386 | struct eventfd_ctx *eventfd, const char *args); |
| 387 | /* |
| 388 | * unregister_event() callback will be called when userspace |
| 389 | * closes the eventfd or on cgroup removing. |
| 390 | * This callback must be implemented, if you want provide |
| 391 | * notification functionality. |
| 392 | */ |
| 393 | void (*unregister_event)(struct cgroup *cgrp, struct cftype *cft, |
| 394 | struct eventfd_ctx *eventfd); |
| 395 | }; |
| 396 | |
| 397 | /* |
| 398 | * cftype_sets describe cftypes belonging to a subsystem and are chained at |
| 399 | * cgroup_subsys->cftsets. Each cftset points to an array of cftypes |
| 400 | * terminated by zero length name. |
| 401 | */ |
| 402 | struct cftype_set { |
| 403 | struct list_head node; /* chained at subsys->cftsets */ |
| 404 | struct cftype *cfts; |
| 405 | }; |
| 406 | |
| 407 | struct cgroup_scanner { |
| 408 | struct cgroup *cg; |
| 409 | int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); |
| 410 | void (*process_task)(struct task_struct *p, |
| 411 | struct cgroup_scanner *scan); |
| 412 | struct ptr_heap *heap; |
| 413 | void *data; |
| 414 | }; |
| 415 | |
| 416 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); |
| 417 | int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); |
| 418 | |
| 419 | int cgroup_is_removed(const struct cgroup *cgrp); |
| 420 | |
| 421 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); |
| 422 | |
| 423 | int cgroup_task_count(const struct cgroup *cgrp); |
| 424 | |
| 425 | /* Return true if cgrp is a descendant of the task's cgroup */ |
| 426 | int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task); |
| 427 | |
| 428 | /* |
| 429 | * When the subsys has to access css and may add permanent refcnt to css, |
| 430 | * it should take care of racy conditions with rmdir(). Following set of |
| 431 | * functions, is for stop/restart rmdir if necessary. |
| 432 | * Because these will call css_get/put, "css" should be alive css. |
| 433 | * |
| 434 | * cgroup_exclude_rmdir(); |
| 435 | * ...do some jobs which may access arbitrary empty cgroup |
| 436 | * cgroup_release_and_wakeup_rmdir(); |
| 437 | * |
| 438 | * When someone removes a cgroup while cgroup_exclude_rmdir() holds it, |
| 439 | * it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up. |
| 440 | */ |
| 441 | |
| 442 | void cgroup_exclude_rmdir(struct cgroup_subsys_state *css); |
| 443 | void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css); |
| 444 | |
| 445 | /* |
| 446 | * Control Group taskset, used to pass around set of tasks to cgroup_subsys |
| 447 | * methods. |
| 448 | */ |
| 449 | struct cgroup_taskset; |
| 450 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset); |
| 451 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset); |
| 452 | struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset); |
| 453 | int cgroup_taskset_size(struct cgroup_taskset *tset); |
| 454 | |
| 455 | /** |
| 456 | * cgroup_taskset_for_each - iterate cgroup_taskset |
| 457 | * @task: the loop cursor |
| 458 | * @skip_cgrp: skip if task's cgroup matches this, %NULL to iterate through all |
| 459 | * @tset: taskset to iterate |
| 460 | */ |
| 461 | #define cgroup_taskset_for_each(task, skip_cgrp, tset) \ |
| 462 | for ((task) = cgroup_taskset_first((tset)); (task); \ |
| 463 | (task) = cgroup_taskset_next((tset))) \ |
| 464 | if (!(skip_cgrp) || \ |
| 465 | cgroup_taskset_cur_cgroup((tset)) != (skip_cgrp)) |
| 466 | |
| 467 | /* |
| 468 | * Control Group subsystem type. |
| 469 | * See Documentation/cgroups/cgroups.txt for details |
| 470 | */ |
| 471 | |
| 472 | struct cgroup_subsys { |
| 473 | struct cgroup_subsys_state *(*create)(struct cgroup *cgrp); |
| 474 | int (*pre_destroy)(struct cgroup *cgrp); |
| 475 | void (*destroy)(struct cgroup *cgrp); |
| 476 | int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset); |
| 477 | void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset); |
| 478 | void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset); |
| 479 | void (*fork)(struct task_struct *task); |
| 480 | void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp, |
| 481 | struct task_struct *task); |
| 482 | void (*post_clone)(struct cgroup *cgrp); |
| 483 | void (*bind)(struct cgroup *root); |
| 484 | |
| 485 | int subsys_id; |
| 486 | int active; |
| 487 | int disabled; |
| 488 | int early_init; |
| 489 | /* |
| 490 | * True if this subsys uses ID. ID is not available before cgroup_init() |
| 491 | * (not available in early_init time.) |
| 492 | */ |
| 493 | bool use_id; |
| 494 | |
| 495 | /* |
| 496 | * If %true, cgroup removal will try to clear css refs by retrying |
| 497 | * ss->pre_destroy() until there's no css ref left. This behavior |
| 498 | * is strictly for backward compatibility and will be removed as |
| 499 | * soon as the current user (memcg) is updated. |
| 500 | * |
| 501 | * If %false, ss->pre_destroy() can't fail and cgroup removal won't |
| 502 | * wait for css refs to drop to zero before proceeding. |
| 503 | */ |
| 504 | bool __DEPRECATED_clear_css_refs; |
| 505 | |
| 506 | #define MAX_CGROUP_TYPE_NAMELEN 32 |
| 507 | const char *name; |
| 508 | |
| 509 | /* |
| 510 | * Link to parent, and list entry in parent's children. |
| 511 | * Protected by cgroup_lock() |
| 512 | */ |
| 513 | struct cgroupfs_root *root; |
| 514 | struct list_head sibling; |
| 515 | /* used when use_id == true */ |
| 516 | struct idr idr; |
| 517 | spinlock_t id_lock; |
| 518 | |
| 519 | /* list of cftype_sets */ |
| 520 | struct list_head cftsets; |
| 521 | |
| 522 | /* base cftypes, automatically [de]registered with subsys itself */ |
| 523 | struct cftype *base_cftypes; |
| 524 | struct cftype_set base_cftset; |
| 525 | |
| 526 | /* should be defined only by modular subsystems */ |
| 527 | struct module *module; |
| 528 | }; |
| 529 | |
| 530 | #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; |
| 531 | #include <linux/cgroup_subsys.h> |
| 532 | #undef SUBSYS |
| 533 | |
| 534 | static inline struct cgroup_subsys_state *cgroup_subsys_state( |
| 535 | struct cgroup *cgrp, int subsys_id) |
| 536 | { |
| 537 | return cgrp->subsys[subsys_id]; |
| 538 | } |
| 539 | |
| 540 | /* |
| 541 | * function to get the cgroup_subsys_state which allows for extra |
| 542 | * rcu_dereference_check() conditions, such as locks used during the |
| 543 | * cgroup_subsys::attach() methods. |
| 544 | */ |
| 545 | #define task_subsys_state_check(task, subsys_id, __c) \ |
| 546 | rcu_dereference_check(task->cgroups->subsys[subsys_id], \ |
| 547 | lockdep_is_held(&task->alloc_lock) || \ |
| 548 | cgroup_lock_is_held() || (__c)) |
| 549 | |
| 550 | static inline struct cgroup_subsys_state * |
| 551 | task_subsys_state(struct task_struct *task, int subsys_id) |
| 552 | { |
| 553 | return task_subsys_state_check(task, subsys_id, false); |
| 554 | } |
| 555 | |
| 556 | static inline struct cgroup* task_cgroup(struct task_struct *task, |
| 557 | int subsys_id) |
| 558 | { |
| 559 | return task_subsys_state(task, subsys_id)->cgroup; |
| 560 | } |
| 561 | |
| 562 | /* A cgroup_iter should be treated as an opaque object */ |
| 563 | struct cgroup_iter { |
| 564 | struct list_head *cg_link; |
| 565 | struct list_head *task; |
| 566 | }; |
| 567 | |
| 568 | /* |
| 569 | * To iterate across the tasks in a cgroup: |
| 570 | * |
| 571 | * 1) call cgroup_iter_start to initialize an iterator |
| 572 | * |
| 573 | * 2) call cgroup_iter_next() to retrieve member tasks until it |
| 574 | * returns NULL or until you want to end the iteration |
| 575 | * |
| 576 | * 3) call cgroup_iter_end() to destroy the iterator. |
| 577 | * |
| 578 | * Or, call cgroup_scan_tasks() to iterate through every task in a |
| 579 | * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling |
| 580 | * the test_task() callback, but not while calling the process_task() |
| 581 | * callback. |
| 582 | */ |
| 583 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); |
| 584 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
| 585 | struct cgroup_iter *it); |
| 586 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); |
| 587 | int cgroup_scan_tasks(struct cgroup_scanner *scan); |
| 588 | int cgroup_attach_task(struct cgroup *, struct task_struct *); |
| 589 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); |
| 590 | |
| 591 | /* |
| 592 | * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works |
| 593 | * if cgroup_subsys.use_id == true. It can be used for looking up and scanning. |
| 594 | * CSS ID is assigned at cgroup allocation (create) automatically |
| 595 | * and removed when subsys calls free_css_id() function. This is because |
| 596 | * the lifetime of cgroup_subsys_state is subsys's matter. |
| 597 | * |
| 598 | * Looking up and scanning function should be called under rcu_read_lock(). |
| 599 | * Taking cgroup_mutex is not necessary for following calls. |
| 600 | * But the css returned by this routine can be "not populated yet" or "being |
| 601 | * destroyed". The caller should check css and cgroup's status. |
| 602 | */ |
| 603 | |
| 604 | /* |
| 605 | * Typically Called at ->destroy(), or somewhere the subsys frees |
| 606 | * cgroup_subsys_state. |
| 607 | */ |
| 608 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css); |
| 609 | |
| 610 | /* Find a cgroup_subsys_state which has given ID */ |
| 611 | |
| 612 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id); |
| 613 | |
| 614 | /* |
| 615 | * Get a cgroup whose id is greater than or equal to id under tree of root. |
| 616 | * Returning a cgroup_subsys_state or NULL. |
| 617 | */ |
| 618 | struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id, |
| 619 | struct cgroup_subsys_state *root, int *foundid); |
| 620 | |
| 621 | /* Returns true if root is ancestor of cg */ |
| 622 | bool css_is_ancestor(struct cgroup_subsys_state *cg, |
| 623 | const struct cgroup_subsys_state *root); |
| 624 | |
| 625 | /* Get id and depth of css */ |
| 626 | unsigned short css_id(struct cgroup_subsys_state *css); |
| 627 | unsigned short css_depth(struct cgroup_subsys_state *css); |
| 628 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id); |
| 629 | |
| 630 | #else /* !CONFIG_CGROUPS */ |
| 631 | |
| 632 | static inline int cgroup_init_early(void) { return 0; } |
| 633 | static inline int cgroup_init(void) { return 0; } |
| 634 | static inline void cgroup_fork(struct task_struct *p) {} |
| 635 | static inline void cgroup_fork_callbacks(struct task_struct *p) {} |
| 636 | static inline void cgroup_post_fork(struct task_struct *p) {} |
| 637 | static inline void cgroup_exit(struct task_struct *p, int callbacks) {} |
| 638 | |
| 639 | static inline void cgroup_lock(void) {} |
| 640 | static inline void cgroup_unlock(void) {} |
| 641 | static inline int cgroupstats_build(struct cgroupstats *stats, |
| 642 | struct dentry *dentry) |
| 643 | { |
| 644 | return -EINVAL; |
| 645 | } |
| 646 | |
| 647 | /* No cgroups - nothing to do */ |
| 648 | static inline int cgroup_attach_task_all(struct task_struct *from, |
| 649 | struct task_struct *t) |
| 650 | { |
| 651 | return 0; |
| 652 | } |
| 653 | |
| 654 | #endif /* !CONFIG_CGROUPS */ |
| 655 | |
| 656 | #endif /* _LINUX_CGROUP_H */ |