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 cpu_relax(); 103 } 104 return true; 105 } 106 107 /* 108 * css_put() should be called to release a reference taken by 109 * css_get() or css_tryget() 110 */ 111 112 extern void __css_put(struct cgroup_subsys_state *css); 113 static inline void css_put(struct cgroup_subsys_state *css) 114 { 115 if (!test_bit(CSS_ROOT, &css->flags)) 116 __css_put(css); 117 } 118 119 /* bits in struct cgroup flags field */ 120 enum { 121 /* Control Group is dead */ 122 CGRP_REMOVED, 123 /* Control Group has previously had a child cgroup or a task, 124 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) */ 125 CGRP_RELEASABLE, 126 /* Control Group requires release notifications to userspace */ 127 CGRP_NOTIFY_ON_RELEASE, 128 }; 129 130 struct cgroup { 131 unsigned long flags; /* "unsigned long" so bitops work */ 132 133 /* count users of this cgroup. >0 means busy, but doesn't 134 * necessarily indicate the number of tasks in the 135 * cgroup */ 136 atomic_t count; 137 138 /* 139 * We link our 'sibling' struct into our parent's 'children'. 140 * Our children link their 'sibling' into our 'children'. 141 */ 142 struct list_head sibling; /* my parent's children */ 143 struct list_head children; /* my children */ 144 145 struct cgroup *parent; /* my parent */ 146 struct dentry *dentry; /* cgroup fs entry, RCU protected */ 147 148 /* Private pointers for each registered subsystem */ 149 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; 150 151 struct cgroupfs_root *root; 152 struct cgroup *top_cgroup; 153 154 /* 155 * List of cg_cgroup_links pointing at css_sets with 156 * tasks in this cgroup. Protected by css_set_lock 157 */ 158 struct list_head css_sets; 159 160 /* 161 * Linked list running through all cgroups that can 162 * potentially be reaped by the release agent. Protected by 163 * release_list_lock 164 */ 165 struct list_head release_list; 166 167 /* pids_mutex protects the fields below */ 168 struct rw_semaphore pids_mutex; 169 /* Array of process ids in the cgroup */ 170 pid_t *tasks_pids; 171 /* How many files are using the current tasks_pids array */ 172 int pids_use_count; 173 /* Length of the current tasks_pids array */ 174 int pids_length; 175 176 /* For RCU-protected deletion */ 177 struct rcu_head rcu_head; 178 }; 179 180 /* A css_set is a structure holding pointers to a set of 181 * cgroup_subsys_state objects. This saves space in the task struct 182 * object and speeds up fork()/exit(), since a single inc/dec and a 183 * list_add()/del() can bump the reference count on the entire 184 * cgroup set for a task. 185 */ 186 187 struct css_set { 188 189 /* Reference count */ 190 atomic_t refcount; 191 192 /* 193 * List running through all cgroup groups in the same hash 194 * slot. Protected by css_set_lock 195 */ 196 struct hlist_node hlist; 197 198 /* 199 * List running through all tasks using this cgroup 200 * group. Protected by css_set_lock 201 */ 202 struct list_head tasks; 203 204 /* 205 * List of cg_cgroup_link objects on link chains from 206 * cgroups referenced from this css_set. Protected by 207 * css_set_lock 208 */ 209 struct list_head cg_links; 210 211 /* 212 * Set of subsystem states, one for each subsystem. This array 213 * is immutable after creation apart from the init_css_set 214 * during subsystem registration (at boot time). 215 */ 216 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; 217 }; 218 219 /* 220 * cgroup_map_cb is an abstract callback API for reporting map-valued 221 * control files 222 */ 223 224 struct cgroup_map_cb { 225 int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); 226 void *state; 227 }; 228 229 /* struct cftype: 230 * 231 * The files in the cgroup filesystem mostly have a very simple read/write 232 * handling, some common function will take care of it. Nevertheless some cases 233 * (read tasks) are special and therefore I define this structure for every 234 * kind of file. 235 * 236 * 237 * When reading/writing to a file: 238 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata 239 * - the 'cftype' of the file is file->f_dentry->d_fsdata 240 */ 241 242 #define MAX_CFTYPE_NAME 64 243 struct cftype { 244 /* By convention, the name should begin with the name of the 245 * subsystem, followed by a period */ 246 char name[MAX_CFTYPE_NAME]; 247 int private; 248 249 /* 250 * If non-zero, defines the maximum length of string that can 251 * be passed to write_string; defaults to 64 252 */ 253 size_t max_write_len; 254 255 int (*open)(struct inode *inode, struct file *file); 256 ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, 257 struct file *file, 258 char __user *buf, size_t nbytes, loff_t *ppos); 259 /* 260 * read_u64() is a shortcut for the common case of returning a 261 * single integer. Use it in place of read() 262 */ 263 u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft); 264 /* 265 * read_s64() is a signed version of read_u64() 266 */ 267 s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft); 268 /* 269 * read_map() is used for defining a map of key/value 270 * pairs. It should call cb->fill(cb, key, value) for each 271 * entry. The key/value pairs (and their ordering) should not 272 * change between reboots. 273 */ 274 int (*read_map)(struct cgroup *cont, struct cftype *cft, 275 struct cgroup_map_cb *cb); 276 /* 277 * read_seq_string() is used for outputting a simple sequence 278 * using seqfile. 279 */ 280 int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, 281 struct seq_file *m); 282 283 ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, 284 struct file *file, 285 const char __user *buf, size_t nbytes, loff_t *ppos); 286 287 /* 288 * write_u64() is a shortcut for the common case of accepting 289 * a single integer (as parsed by simple_strtoull) from 290 * userspace. Use in place of write(); return 0 or error. 291 */ 292 int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val); 293 /* 294 * write_s64() is a signed version of write_u64() 295 */ 296 int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val); 297 298 /* 299 * write_string() is passed a nul-terminated kernelspace 300 * buffer of maximum length determined by max_write_len. 301 * Returns 0 or -ve error code. 302 */ 303 int (*write_string)(struct cgroup *cgrp, struct cftype *cft, 304 const char *buffer); 305 /* 306 * trigger() callback can be used to get some kick from the 307 * userspace, when the actual string written is not important 308 * at all. The private field can be used to determine the 309 * kick type for multiplexing. 310 */ 311 int (*trigger)(struct cgroup *cgrp, unsigned int event); 312 313 int (*release)(struct inode *inode, struct file *file); 314 }; 315 316 struct cgroup_scanner { 317 struct cgroup *cg; 318 int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); 319 void (*process_task)(struct task_struct *p, 320 struct cgroup_scanner *scan); 321 struct ptr_heap *heap; 322 }; 323 324 /* Add a new file to the given cgroup directory. Should only be 325 * called by subsystems from within a populate() method */ 326 int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, 327 const struct cftype *cft); 328 329 /* Add a set of new files to the given cgroup directory. Should 330 * only be called by subsystems from within a populate() method */ 331 int cgroup_add_files(struct cgroup *cgrp, 332 struct cgroup_subsys *subsys, 333 const struct cftype cft[], 334 int count); 335 336 int cgroup_is_removed(const struct cgroup *cgrp); 337 338 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); 339 340 int cgroup_task_count(const struct cgroup *cgrp); 341 342 /* Return true if the cgroup is a descendant of the current cgroup */ 343 int cgroup_is_descendant(const struct cgroup *cgrp); 344 345 /* Control Group subsystem type. See Documentation/cgroups.txt for details */ 346 347 struct cgroup_subsys { 348 struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss, 349 struct cgroup *cgrp); 350 void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); 351 void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); 352 int (*can_attach)(struct cgroup_subsys *ss, 353 struct cgroup *cgrp, struct task_struct *tsk); 354 void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, 355 struct cgroup *old_cgrp, struct task_struct *tsk); 356 void (*fork)(struct cgroup_subsys *ss, struct task_struct *task); 357 void (*exit)(struct cgroup_subsys *ss, struct task_struct *task); 358 int (*populate)(struct cgroup_subsys *ss, 359 struct cgroup *cgrp); 360 void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp); 361 void (*bind)(struct cgroup_subsys *ss, struct cgroup *root); 362 363 int subsys_id; 364 int active; 365 int disabled; 366 int early_init; 367 #define MAX_CGROUP_TYPE_NAMELEN 32 368 const char *name; 369 370 /* 371 * Protects sibling/children links of cgroups in this 372 * hierarchy, plus protects which hierarchy (or none) the 373 * subsystem is a part of (i.e. root/sibling). To avoid 374 * potential deadlocks, the following operations should not be 375 * undertaken while holding any hierarchy_mutex: 376 * 377 * - allocating memory 378 * - initiating hotplug events 379 */ 380 struct mutex hierarchy_mutex; 381 struct lock_class_key subsys_key; 382 383 /* 384 * Link to parent, and list entry in parent's children. 385 * Protected by this->hierarchy_mutex and cgroup_lock() 386 */ 387 struct cgroupfs_root *root; 388 struct list_head sibling; 389 }; 390 391 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; 392 #include <linux/cgroup_subsys.h> 393 #undef SUBSYS 394 395 static inline struct cgroup_subsys_state *cgroup_subsys_state( 396 struct cgroup *cgrp, int subsys_id) 397 { 398 return cgrp->subsys[subsys_id]; 399 } 400 401 static inline struct cgroup_subsys_state *task_subsys_state( 402 struct task_struct *task, int subsys_id) 403 { 404 return rcu_dereference(task->cgroups->subsys[subsys_id]); 405 } 406 407 static inline struct cgroup* task_cgroup(struct task_struct *task, 408 int subsys_id) 409 { 410 return task_subsys_state(task, subsys_id)->cgroup; 411 } 412 413 int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss, 414 char *nodename); 415 416 /* A cgroup_iter should be treated as an opaque object */ 417 struct cgroup_iter { 418 struct list_head *cg_link; 419 struct list_head *task; 420 }; 421 422 /* To iterate across the tasks in a cgroup: 423 * 424 * 1) call cgroup_iter_start to intialize an iterator 425 * 426 * 2) call cgroup_iter_next() to retrieve member tasks until it 427 * returns NULL or until you want to end the iteration 428 * 429 * 3) call cgroup_iter_end() to destroy the iterator. 430 * 431 * Or, call cgroup_scan_tasks() to iterate through every task in a cpuset. 432 * - cgroup_scan_tasks() holds the css_set_lock when calling the test_task() 433 * callback, but not while calling the process_task() callback. 434 */ 435 void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); 436 struct task_struct *cgroup_iter_next(struct cgroup *cgrp, 437 struct cgroup_iter *it); 438 void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); 439 int cgroup_scan_tasks(struct cgroup_scanner *scan); 440 int cgroup_attach_task(struct cgroup *, struct task_struct *); 441 442 #else /* !CONFIG_CGROUPS */ 443 444 static inline int cgroup_init_early(void) { return 0; } 445 static inline int cgroup_init(void) { return 0; } 446 static inline void cgroup_fork(struct task_struct *p) {} 447 static inline void cgroup_fork_callbacks(struct task_struct *p) {} 448 static inline void cgroup_post_fork(struct task_struct *p) {} 449 static inline void cgroup_exit(struct task_struct *p, int callbacks) {} 450 451 static inline void cgroup_lock(void) {} 452 static inline void cgroup_unlock(void) {} 453 static inline int cgroupstats_build(struct cgroupstats *stats, 454 struct dentry *dentry) 455 { 456 return -EINVAL; 457 } 458 459 #endif /* !CONFIG_CGROUPS */ 460 461 #endif /* _LINUX_CGROUP_H */ 462