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 19 #ifdef CONFIG_CGROUPS 20 21 struct cgroupfs_root; 22 struct cgroup_subsys; 23 struct inode; 24 struct cgroup; 25 26 extern int cgroup_init_early(void); 27 extern int cgroup_init(void); 28 extern void cgroup_lock(void); 29 extern bool cgroup_lock_live_group(struct cgroup *cgrp); 30 extern void cgroup_unlock(void); 31 extern void cgroup_fork(struct task_struct *p); 32 extern void cgroup_fork_callbacks(struct task_struct *p); 33 extern void cgroup_post_fork(struct task_struct *p); 34 extern void cgroup_exit(struct task_struct *p, int run_callbacks); 35 extern int cgroupstats_build(struct cgroupstats *stats, 36 struct dentry *dentry); 37 38 extern struct file_operations proc_cgroup_operations; 39 40 /* Define the enumeration of all cgroup subsystems */ 41 #define SUBSYS(_x) _x ## _subsys_id, 42 enum cgroup_subsys_id { 43 #include <linux/cgroup_subsys.h> 44 CGROUP_SUBSYS_COUNT 45 }; 46 #undef SUBSYS 47 48 /* Per-subsystem/per-cgroup state maintained by the system. */ 49 struct cgroup_subsys_state { 50 /* The cgroup that this subsystem is attached to. Useful 51 * for subsystems that want to know about the cgroup 52 * hierarchy structure */ 53 struct cgroup *cgroup; 54 55 /* State maintained by the cgroup system to allow subsystems 56 * to be "busy". Should be accessed via css_get(), 57 * css_tryget() and and css_put(). */ 58 59 atomic_t refcnt; 60 61 unsigned long flags; 62 }; 63 64 /* bits in struct cgroup_subsys_state flags field */ 65 enum { 66 CSS_ROOT, /* This CSS is the root of the subsystem */ 67 CSS_REMOVED, /* This CSS is dead */ 68 }; 69 70 /* 71 * Call css_get() to hold a reference on the css; it can be used 72 * for a reference obtained via: 73 * - an existing ref-counted reference to the css 74 * - task->cgroups for a locked task 75 */ 76 77 static inline void css_get(struct cgroup_subsys_state *css) 78 { 79 /* We don't need to reference count the root state */ 80 if (!test_bit(CSS_ROOT, &css->flags)) 81 atomic_inc(&css->refcnt); 82 } 83 84 static inline bool css_is_removed(struct cgroup_subsys_state *css) 85 { 86 return test_bit(CSS_REMOVED, &css->flags); 87 } 88 89 /* 90 * Call css_tryget() to take a reference on a css if your existing 91 * (known-valid) reference isn't already ref-counted. Returns false if 92 * the css has been destroyed. 93 */ 94 95 static inline bool css_tryget(struct cgroup_subsys_state *css) 96 { 97 if (test_bit(CSS_ROOT, &css->flags)) 98 return true; 99 while (!atomic_inc_not_zero(&css->refcnt)) { 100 if (test_bit(CSS_REMOVED, &css->flags)) 101 return false; 102 } 103 return true; 104 } 105 106 /* 107 * css_put() should be called to release a reference taken by 108 * css_get() or css_tryget() 109 */ 110 111 extern void __css_put(struct cgroup_subsys_state *css); 112 static inline void css_put(struct cgroup_subsys_state *css) 113 { 114 if (!test_bit(CSS_ROOT, &css->flags)) 115 __css_put(css); 116 } 117 118 /* bits in struct cgroup flags field */ 119 enum { 120 /* Control Group is dead */ 121 CGRP_REMOVED, 122 /* Control Group has previously had a child cgroup or a task, 123 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) */ 124 CGRP_RELEASABLE, 125 /* Control Group requires release notifications to userspace */ 126 CGRP_NOTIFY_ON_RELEASE, 127 }; 128 129 struct cgroup { 130 unsigned long flags; /* "unsigned long" so bitops work */ 131 132 /* count users of this cgroup. >0 means busy, but doesn't 133 * necessarily indicate the number of tasks in the 134 * cgroup */ 135 atomic_t count; 136 137 /* 138 * We link our 'sibling' struct into our parent's 'children'. 139 * Our children link their 'sibling' into our 'children'. 140 */ 141 struct list_head sibling; /* my parent's children */ 142 struct list_head children; /* my children */ 143 144 struct cgroup *parent; /* my parent */ 145 struct dentry *dentry; /* cgroup fs entry, RCU protected */ 146 147 /* Private pointers for each registered subsystem */ 148 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; 149 150 struct cgroupfs_root *root; 151 struct cgroup *top_cgroup; 152 153 /* 154 * List of cg_cgroup_links pointing at css_sets with 155 * tasks in this cgroup. Protected by css_set_lock 156 */ 157 struct list_head css_sets; 158 159 /* 160 * Linked list running through all cgroups that can 161 * potentially be reaped by the release agent. Protected by 162 * release_list_lock 163 */ 164 struct list_head release_list; 165 166 /* pids_mutex protects the fields below */ 167 struct rw_semaphore pids_mutex; 168 /* Array of process ids in the cgroup */ 169 pid_t *tasks_pids; 170 /* How many files are using the current tasks_pids array */ 171 int pids_use_count; 172 /* Length of the current tasks_pids array */ 173 int pids_length; 174 175 /* For RCU-protected deletion */ 176 struct rcu_head rcu_head; 177 }; 178 179 /* A css_set is a structure holding pointers to a set of 180 * cgroup_subsys_state objects. This saves space in the task struct 181 * object and speeds up fork()/exit(), since a single inc/dec and a 182 * list_add()/del() can bump the reference count on the entire 183 * cgroup set for a task. 184 */ 185 186 struct css_set { 187 188 /* Reference count */ 189 atomic_t refcount; 190 191 /* 192 * List running through all cgroup groups in the same hash 193 * slot. Protected by css_set_lock 194 */ 195 struct hlist_node hlist; 196 197 /* 198 * List running through all tasks using this cgroup 199 * group. Protected by css_set_lock 200 */ 201 struct list_head tasks; 202 203 /* 204 * List of cg_cgroup_link objects on link chains from 205 * cgroups referenced from this css_set. Protected by 206 * css_set_lock 207 */ 208 struct list_head cg_links; 209 210 /* 211 * Set of subsystem states, one for each subsystem. This array 212 * is immutable after creation apart from the init_css_set 213 * during subsystem registration (at boot time). 214 */ 215 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; 216 }; 217 218 /* 219 * cgroup_map_cb is an abstract callback API for reporting map-valued 220 * control files 221 */ 222 223 struct cgroup_map_cb { 224 int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); 225 void *state; 226 }; 227 228 /* struct cftype: 229 * 230 * The files in the cgroup filesystem mostly have a very simple read/write 231 * handling, some common function will take care of it. Nevertheless some cases 232 * (read tasks) are special and therefore I define this structure for every 233 * kind of file. 234 * 235 * 236 * When reading/writing to a file: 237 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata 238 * - the 'cftype' of the file is file->f_dentry->d_fsdata 239 */ 240 241 #define MAX_CFTYPE_NAME 64 242 struct cftype { 243 /* By convention, the name should begin with the name of the 244 * subsystem, followed by a period */ 245 char name[MAX_CFTYPE_NAME]; 246 int private; 247 248 /* 249 * If non-zero, defines the maximum length of string that can 250 * be passed to write_string; defaults to 64 251 */ 252 size_t max_write_len; 253 254 int (*open)(struct inode *inode, struct file *file); 255 ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, 256 struct file *file, 257 char __user *buf, size_t nbytes, loff_t *ppos); 258 /* 259 * read_u64() is a shortcut for the common case of returning a 260 * single integer. Use it in place of read() 261 */ 262 u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft); 263 /* 264 * read_s64() is a signed version of read_u64() 265 */ 266 s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft); 267 /* 268 * read_map() is used for defining a map of key/value 269 * pairs. It should call cb->fill(cb, key, value) for each 270 * entry. The key/value pairs (and their ordering) should not 271 * change between reboots. 272 */ 273 int (*read_map)(struct cgroup *cont, struct cftype *cft, 274 struct cgroup_map_cb *cb); 275 /* 276 * read_seq_string() is used for outputting a simple sequence 277 * using seqfile. 278 */ 279 int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, 280 struct seq_file *m); 281 282 ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, 283 struct file *file, 284 const char __user *buf, size_t nbytes, loff_t *ppos); 285 286 /* 287 * write_u64() is a shortcut for the common case of accepting 288 * a single integer (as parsed by simple_strtoull) from 289 * userspace. Use in place of write(); return 0 or error. 290 */ 291 int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val); 292 /* 293 * write_s64() is a signed version of write_u64() 294 */ 295 int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val); 296 297 /* 298 * write_string() is passed a nul-terminated kernelspace 299 * buffer of maximum length determined by max_write_len. 300 * Returns 0 or -ve error code. 301 */ 302 int (*write_string)(struct cgroup *cgrp, struct cftype *cft, 303 const char *buffer); 304 /* 305 * trigger() callback can be used to get some kick from the 306 * userspace, when the actual string written is not important 307 * at all. The private field can be used to determine the 308 * kick type for multiplexing. 309 */ 310 int (*trigger)(struct cgroup *cgrp, unsigned int event); 311 312 int (*release)(struct inode *inode, struct file *file); 313 }; 314 315 struct cgroup_scanner { 316 struct cgroup *cg; 317 int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); 318 void (*process_task)(struct task_struct *p, 319 struct cgroup_scanner *scan); 320 struct ptr_heap *heap; 321 }; 322 323 /* Add a new file to the given cgroup directory. Should only be 324 * called by subsystems from within a populate() method */ 325 int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, 326 const struct cftype *cft); 327 328 /* Add a set of new files to the given cgroup directory. Should 329 * only be called by subsystems from within a populate() method */ 330 int cgroup_add_files(struct cgroup *cgrp, 331 struct cgroup_subsys *subsys, 332 const struct cftype cft[], 333 int count); 334 335 int cgroup_is_removed(const struct cgroup *cgrp); 336 337 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); 338 339 int cgroup_task_count(const struct cgroup *cgrp); 340 341 /* Return true if the cgroup is a descendant of the current cgroup */ 342 int cgroup_is_descendant(const struct cgroup *cgrp); 343 344 /* Control Group subsystem type. See Documentation/cgroups.txt for details */ 345 346 struct cgroup_subsys { 347 struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss, 348 struct cgroup *cgrp); 349 void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); 350 void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); 351 int (*can_attach)(struct cgroup_subsys *ss, 352 struct cgroup *cgrp, struct task_struct *tsk); 353 void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, 354 struct cgroup *old_cgrp, struct task_struct *tsk); 355 void (*fork)(struct cgroup_subsys *ss, struct task_struct *task); 356 void (*exit)(struct cgroup_subsys *ss, struct task_struct *task); 357 int (*populate)(struct cgroup_subsys *ss, 358 struct cgroup *cgrp); 359 void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); 360 void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); 361 362 int subsys_id; 363 int active; 364 int disabled; 365 int early_init; 366 #define MAX_CGROUP_TYPE_NAMELEN 32 367 const char *name; 368 369 /* 370 * Protects sibling/children links of cgroups in this 371 * hierarchy, plus protects which hierarchy (or none) the 372 * subsystem is a part of (i.e. root/sibling). To avoid 373 * potential deadlocks, the following operations should not be 374 * undertaken while holding any hierarchy_mutex: 375 * 376 * - allocating memory 377 * - initiating hotplug events 378 */ 379 struct mutex hierarchy_mutex; 380 381 /* 382 * Link to parent, and list entry in parent's children. 383 * Protected by this->hierarchy_mutex and cgroup_lock() 384 */ 385 struct cgroupfs_root *root; 386 struct list_head sibling; 387 }; 388 389 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; 390 #include <linux/cgroup_subsys.h> 391 #undef SUBSYS 392 393 static inline struct cgroup_subsys_state *cgroup_subsys_state( 394 struct cgroup *cgrp, int subsys_id) 395 { 396 return cgrp->subsys[subsys_id]; 397 } 398 399 static inline struct cgroup_subsys_state *task_subsys_state( 400 struct task_struct *task, int subsys_id) 401 { 402 return rcu_dereference(task->cgroups->subsys[subsys_id]); 403 } 404 405 static inline struct cgroup* task_cgroup(struct task_struct *task, 406 int subsys_id) 407 { 408 return task_subsys_state(task, subsys_id)->cgroup; 409 } 410 411 int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss, 412 char *nodename); 413 414 /* A cgroup_iter should be treated as an opaque object */ 415 struct cgroup_iter { 416 struct list_head *cg_link; 417 struct list_head *task; 418 }; 419 420 /* To iterate across the tasks in a cgroup: 421 * 422 * 1) call cgroup_iter_start to intialize an iterator 423 * 424 * 2) call cgroup_iter_next() to retrieve member tasks until it 425 * returns NULL or until you want to end the iteration 426 * 427 * 3) call cgroup_iter_end() to destroy the iterator. 428 * 429 * Or, call cgroup_scan_tasks() to iterate through every task in a cpuset. 430 * - cgroup_scan_tasks() holds the css_set_lock when calling the test_task() 431 * callback, but not while calling the process_task() callback. 432 */ 433 void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); 434 struct task_struct *cgroup_iter_next(struct cgroup *cgrp, 435 struct cgroup_iter *it); 436 void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); 437 int cgroup_scan_tasks(struct cgroup_scanner *scan); 438 int cgroup_attach_task(struct cgroup *, struct task_struct *); 439 440 #else /* !CONFIG_CGROUPS */ 441 442 static inline int cgroup_init_early(void) { return 0; } 443 static inline int cgroup_init(void) { return 0; } 444 static inline void cgroup_fork(struct task_struct *p) {} 445 static inline void cgroup_fork_callbacks(struct task_struct *p) {} 446 static inline void cgroup_post_fork(struct task_struct *p) {} 447 static inline void cgroup_exit(struct task_struct *p, int callbacks) {} 448 449 static inline void cgroup_lock(void) {} 450 static inline void cgroup_unlock(void) {} 451 static inline int cgroupstats_build(struct cgroupstats *stats, 452 struct dentry *dentry) 453 { 454 return -EINVAL; 455 } 456 457 #endif /* !CONFIG_CGROUPS */ 458 459 #endif /* _LINUX_CGROUP_H */ 460