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