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