1 #ifndef _LINUX_CGROUP_H
2 #define _LINUX_CGROUP_H
6 * Copyright (C) 2003 BULL SA
7 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
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>
28 extern int cgroup_init_early(void);
29 extern int cgroup_init(void);
30 extern void cgroup_lock(void);
31 extern int cgroup_lock_is_held(void);
32 extern bool cgroup_lock_live_group(struct cgroup
*cgrp
);
33 extern void cgroup_unlock(void);
34 extern void cgroup_fork(struct task_struct
*p
);
35 extern void cgroup_fork_callbacks(struct task_struct
*p
);
36 extern void cgroup_post_fork(struct task_struct
*p
);
37 extern void cgroup_exit(struct task_struct
*p
, int run_callbacks
);
38 extern int cgroupstats_build(struct cgroupstats
*stats
,
39 struct dentry
*dentry
);
41 extern const struct file_operations proc_cgroup_operations
;
43 /* Define the enumeration of all cgroup subsystems */
44 #define SUBSYS(_x) _x ## _subsys_id,
45 enum cgroup_subsys_id
{
46 #include <linux/cgroup_subsys.h>
51 /* Per-subsystem/per-cgroup state maintained by the system. */
52 struct cgroup_subsys_state
{
54 * The cgroup that this subsystem is attached to. Useful
55 * for subsystems that want to know about the cgroup
58 struct cgroup
*cgroup
;
61 * State maintained by the cgroup system to allow subsystems
62 * to be "busy". Should be accessed via css_get(),
63 * css_tryget() and and css_put().
69 /* ID for this css, if possible */
73 /* bits in struct cgroup_subsys_state flags field */
75 CSS_ROOT
, /* This CSS is the root of the subsystem */
76 CSS_REMOVED
, /* This CSS is dead */
80 * Call css_get() to hold a reference on the css; it can be used
81 * for a reference obtained via:
82 * - an existing ref-counted reference to the css
83 * - task->cgroups for a locked task
86 static inline void css_get(struct cgroup_subsys_state
*css
)
88 /* We don't need to reference count the root state */
89 if (!test_bit(CSS_ROOT
, &css
->flags
))
90 atomic_inc(&css
->refcnt
);
93 static inline bool css_is_removed(struct cgroup_subsys_state
*css
)
95 return test_bit(CSS_REMOVED
, &css
->flags
);
99 * Call css_tryget() to take a reference on a css if your existing
100 * (known-valid) reference isn't already ref-counted. Returns false if
101 * the css has been destroyed.
104 static inline bool css_tryget(struct cgroup_subsys_state
*css
)
106 if (test_bit(CSS_ROOT
, &css
->flags
))
108 while (!atomic_inc_not_zero(&css
->refcnt
)) {
109 if (test_bit(CSS_REMOVED
, &css
->flags
))
117 * css_put() should be called to release a reference taken by
118 * css_get() or css_tryget()
121 extern void __css_put(struct cgroup_subsys_state
*css
);
122 static inline void css_put(struct cgroup_subsys_state
*css
)
124 if (!test_bit(CSS_ROOT
, &css
->flags
))
128 /* bits in struct cgroup flags field */
130 /* Control Group is dead */
133 * Control Group has previously had a child cgroup or a task,
134 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
137 /* Control Group requires release notifications to userspace */
138 CGRP_NOTIFY_ON_RELEASE
,
140 * A thread in rmdir() is wating for this cgroup.
145 /* which pidlist file are we talking about? */
146 enum cgroup_filetype
{
152 * A pidlist is a list of pids that virtually represents the contents of one
153 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
154 * a pair (one each for procs, tasks) for each pid namespace that's relevant
157 struct cgroup_pidlist
{
159 * used to find which pidlist is wanted. doesn't change as long as
160 * this particular list stays in the list.
162 struct { enum cgroup_filetype type
; struct pid_namespace
*ns
; } key
;
165 /* how many elements the above list has */
167 /* how many files are using the current array */
169 /* each of these stored in a list by its cgroup */
170 struct list_head links
;
171 /* pointer to the cgroup we belong to, for list removal purposes */
172 struct cgroup
*owner
;
173 /* protects the other fields */
174 struct rw_semaphore mutex
;
178 unsigned long flags
; /* "unsigned long" so bitops work */
181 * count users of this cgroup. >0 means busy, but doesn't
182 * necessarily indicate the number of tasks in the cgroup
187 * We link our 'sibling' struct into our parent's 'children'.
188 * Our children link their 'sibling' into our 'children'.
190 struct list_head sibling
; /* my parent's children */
191 struct list_head children
; /* my children */
193 struct cgroup
*parent
; /* my parent */
194 struct dentry
*dentry
; /* cgroup fs entry, RCU protected */
196 /* Private pointers for each registered subsystem */
197 struct cgroup_subsys_state
*subsys
[CGROUP_SUBSYS_COUNT
];
199 struct cgroupfs_root
*root
;
200 struct cgroup
*top_cgroup
;
203 * List of cg_cgroup_links pointing at css_sets with
204 * tasks in this cgroup. Protected by css_set_lock
206 struct list_head css_sets
;
209 * Linked list running through all cgroups that can
210 * potentially be reaped by the release agent. Protected by
213 struct list_head release_list
;
216 * list of pidlists, up to two for each namespace (one for procs, one
217 * for tasks); created on demand.
219 struct list_head pidlists
;
220 struct mutex pidlist_mutex
;
222 /* For RCU-protected deletion */
223 struct rcu_head rcu_head
;
227 * A css_set is a structure holding pointers to a set of
228 * cgroup_subsys_state objects. This saves space in the task struct
229 * object and speeds up fork()/exit(), since a single inc/dec and a
230 * list_add()/del() can bump the reference count on the entire cgroup
236 /* Reference count */
240 * List running through all cgroup groups in the same hash
241 * slot. Protected by css_set_lock
243 struct hlist_node hlist
;
246 * List running through all tasks using this cgroup
247 * group. Protected by css_set_lock
249 struct list_head tasks
;
252 * List of cg_cgroup_link objects on link chains from
253 * cgroups referenced from this css_set. Protected by
256 struct list_head cg_links
;
259 * Set of subsystem states, one for each subsystem. This array
260 * is immutable after creation apart from the init_css_set
261 * during subsystem registration (at boot time).
263 struct cgroup_subsys_state
*subsys
[CGROUP_SUBSYS_COUNT
];
265 /* For RCU-protected deletion */
266 struct rcu_head rcu_head
;
270 * cgroup_map_cb is an abstract callback API for reporting map-valued
274 struct cgroup_map_cb
{
275 int (*fill
)(struct cgroup_map_cb
*cb
, const char *key
, u64 value
);
280 * struct cftype: handler definitions for cgroup control files
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
287 #define MAX_CFTYPE_NAME 64
290 * By convention, the name should begin with the name of the
291 * subsystem, followed by a period
293 char name
[MAX_CFTYPE_NAME
];
296 * If not 0, file mode is set to this value, otherwise it will
297 * be figured out automatically
302 * If non-zero, defines the maximum length of string that can
303 * be passed to write_string; defaults to 64
305 size_t max_write_len
;
307 int (*open
)(struct inode
*inode
, struct file
*file
);
308 ssize_t (*read
)(struct cgroup
*cgrp
, struct cftype
*cft
,
310 char __user
*buf
, size_t nbytes
, loff_t
*ppos
);
312 * read_u64() is a shortcut for the common case of returning a
313 * single integer. Use it in place of read()
315 u64 (*read_u64
)(struct cgroup
*cgrp
, struct cftype
*cft
);
317 * read_s64() is a signed version of read_u64()
319 s64 (*read_s64
)(struct cgroup
*cgrp
, struct cftype
*cft
);
321 * read_map() is used for defining a map of key/value
322 * pairs. It should call cb->fill(cb, key, value) for each
323 * entry. The key/value pairs (and their ordering) should not
324 * change between reboots.
326 int (*read_map
)(struct cgroup
*cont
, struct cftype
*cft
,
327 struct cgroup_map_cb
*cb
);
329 * read_seq_string() is used for outputting a simple sequence
332 int (*read_seq_string
)(struct cgroup
*cont
, struct cftype
*cft
,
335 ssize_t (*write
)(struct cgroup
*cgrp
, struct cftype
*cft
,
337 const char __user
*buf
, size_t nbytes
, loff_t
*ppos
);
340 * write_u64() is a shortcut for the common case of accepting
341 * a single integer (as parsed by simple_strtoull) from
342 * userspace. Use in place of write(); return 0 or error.
344 int (*write_u64
)(struct cgroup
*cgrp
, struct cftype
*cft
, u64 val
);
346 * write_s64() is a signed version of write_u64()
348 int (*write_s64
)(struct cgroup
*cgrp
, struct cftype
*cft
, s64 val
);
351 * write_string() is passed a nul-terminated kernelspace
352 * buffer of maximum length determined by max_write_len.
353 * Returns 0 or -ve error code.
355 int (*write_string
)(struct cgroup
*cgrp
, struct cftype
*cft
,
358 * trigger() callback can be used to get some kick from the
359 * userspace, when the actual string written is not important
360 * at all. The private field can be used to determine the
361 * kick type for multiplexing.
363 int (*trigger
)(struct cgroup
*cgrp
, unsigned int event
);
365 int (*release
)(struct inode
*inode
, struct file
*file
);
368 struct cgroup_scanner
{
370 int (*test_task
)(struct task_struct
*p
, struct cgroup_scanner
*scan
);
371 void (*process_task
)(struct task_struct
*p
,
372 struct cgroup_scanner
*scan
);
373 struct ptr_heap
*heap
;
378 * Add a new file to the given cgroup directory. Should only be
379 * called by subsystems from within a populate() method
381 int cgroup_add_file(struct cgroup
*cgrp
, struct cgroup_subsys
*subsys
,
382 const struct cftype
*cft
);
385 * Add a set of new files to the given cgroup directory. Should
386 * only be called by subsystems from within a populate() method
388 int cgroup_add_files(struct cgroup
*cgrp
,
389 struct cgroup_subsys
*subsys
,
390 const struct cftype cft
[],
393 int cgroup_is_removed(const struct cgroup
*cgrp
);
395 int cgroup_path(const struct cgroup
*cgrp
, char *buf
, int buflen
);
397 int cgroup_task_count(const struct cgroup
*cgrp
);
399 /* Return true if cgrp is a descendant of the task's cgroup */
400 int cgroup_is_descendant(const struct cgroup
*cgrp
, struct task_struct
*task
);
403 * When the subsys has to access css and may add permanent refcnt to css,
404 * it should take care of racy conditions with rmdir(). Following set of
405 * functions, is for stop/restart rmdir if necessary.
406 * Because these will call css_get/put, "css" should be alive css.
408 * cgroup_exclude_rmdir();
409 * ...do some jobs which may access arbitrary empty cgroup
410 * cgroup_release_and_wakeup_rmdir();
412 * When someone removes a cgroup while cgroup_exclude_rmdir() holds it,
413 * it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up.
416 void cgroup_exclude_rmdir(struct cgroup_subsys_state
*css
);
417 void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state
*css
);
420 * Control Group subsystem type.
421 * See Documentation/cgroups/cgroups.txt for details
424 struct cgroup_subsys
{
425 struct cgroup_subsys_state
*(*create
)(struct cgroup_subsys
*ss
,
426 struct cgroup
*cgrp
);
427 int (*pre_destroy
)(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
);
428 void (*destroy
)(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
);
429 int (*can_attach
)(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
430 struct task_struct
*tsk
, bool threadgroup
);
431 void (*attach
)(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
,
432 struct cgroup
*old_cgrp
, struct task_struct
*tsk
,
434 void (*fork
)(struct cgroup_subsys
*ss
, struct task_struct
*task
);
435 void (*exit
)(struct cgroup_subsys
*ss
, struct task_struct
*task
);
436 int (*populate
)(struct cgroup_subsys
*ss
,
437 struct cgroup
*cgrp
);
438 void (*post_clone
)(struct cgroup_subsys
*ss
, struct cgroup
*cgrp
);
439 void (*bind
)(struct cgroup_subsys
*ss
, struct cgroup
*root
);
446 * True if this subsys uses ID. ID is not available before cgroup_init()
447 * (not available in early_init time.)
450 #define MAX_CGROUP_TYPE_NAMELEN 32
454 * Protects sibling/children links of cgroups in this
455 * hierarchy, plus protects which hierarchy (or none) the
456 * subsystem is a part of (i.e. root/sibling). To avoid
457 * potential deadlocks, the following operations should not be
458 * undertaken while holding any hierarchy_mutex:
460 * - allocating memory
461 * - initiating hotplug events
463 struct mutex hierarchy_mutex
;
464 struct lock_class_key subsys_key
;
467 * Link to parent, and list entry in parent's children.
468 * Protected by this->hierarchy_mutex and cgroup_lock()
470 struct cgroupfs_root
*root
;
471 struct list_head sibling
;
472 /* used when use_id == true */
477 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
478 #include <linux/cgroup_subsys.h>
481 static inline struct cgroup_subsys_state
*cgroup_subsys_state(
482 struct cgroup
*cgrp
, int subsys_id
)
484 return cgrp
->subsys
[subsys_id
];
487 static inline struct cgroup_subsys_state
*task_subsys_state(
488 struct task_struct
*task
, int subsys_id
)
490 return rcu_dereference_check(task
->cgroups
->subsys
[subsys_id
],
491 rcu_read_lock_held() ||
492 cgroup_lock_is_held());
495 static inline struct cgroup
* task_cgroup(struct task_struct
*task
,
498 return task_subsys_state(task
, subsys_id
)->cgroup
;
501 int cgroup_clone(struct task_struct
*tsk
, struct cgroup_subsys
*ss
,
504 /* A cgroup_iter should be treated as an opaque object */
506 struct list_head
*cg_link
;
507 struct list_head
*task
;
511 * To iterate across the tasks in a cgroup:
513 * 1) call cgroup_iter_start to intialize an iterator
515 * 2) call cgroup_iter_next() to retrieve member tasks until it
516 * returns NULL or until you want to end the iteration
518 * 3) call cgroup_iter_end() to destroy the iterator.
520 * Or, call cgroup_scan_tasks() to iterate through every task in a
521 * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling
522 * the test_task() callback, but not while calling the process_task()
525 void cgroup_iter_start(struct cgroup
*cgrp
, struct cgroup_iter
*it
);
526 struct task_struct
*cgroup_iter_next(struct cgroup
*cgrp
,
527 struct cgroup_iter
*it
);
528 void cgroup_iter_end(struct cgroup
*cgrp
, struct cgroup_iter
*it
);
529 int cgroup_scan_tasks(struct cgroup_scanner
*scan
);
530 int cgroup_attach_task(struct cgroup
*, struct task_struct
*);
533 * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
534 * if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
535 * CSS ID is assigned at cgroup allocation (create) automatically
536 * and removed when subsys calls free_css_id() function. This is because
537 * the lifetime of cgroup_subsys_state is subsys's matter.
539 * Looking up and scanning function should be called under rcu_read_lock().
540 * Taking cgroup_mutex()/hierarchy_mutex() is not necessary for following calls.
541 * But the css returned by this routine can be "not populated yet" or "being
542 * destroyed". The caller should check css and cgroup's status.
546 * Typically Called at ->destroy(), or somewhere the subsys frees
547 * cgroup_subsys_state.
549 void free_css_id(struct cgroup_subsys
*ss
, struct cgroup_subsys_state
*css
);
551 /* Find a cgroup_subsys_state which has given ID */
553 struct cgroup_subsys_state
*css_lookup(struct cgroup_subsys
*ss
, int id
);
556 * Get a cgroup whose id is greater than or equal to id under tree of root.
557 * Returning a cgroup_subsys_state or NULL.
559 struct cgroup_subsys_state
*css_get_next(struct cgroup_subsys
*ss
, int id
,
560 struct cgroup_subsys_state
*root
, int *foundid
);
562 /* Returns true if root is ancestor of cg */
563 bool css_is_ancestor(struct cgroup_subsys_state
*cg
,
564 const struct cgroup_subsys_state
*root
);
566 /* Get id and depth of css */
567 unsigned short css_id(struct cgroup_subsys_state
*css
);
568 unsigned short css_depth(struct cgroup_subsys_state
*css
);
570 #else /* !CONFIG_CGROUPS */
572 static inline int cgroup_init_early(void) { return 0; }
573 static inline int cgroup_init(void) { return 0; }
574 static inline void cgroup_fork(struct task_struct
*p
) {}
575 static inline void cgroup_fork_callbacks(struct task_struct
*p
) {}
576 static inline void cgroup_post_fork(struct task_struct
*p
) {}
577 static inline void cgroup_exit(struct task_struct
*p
, int callbacks
) {}
579 static inline void cgroup_lock(void) {}
580 static inline void cgroup_unlock(void) {}
581 static inline int cgroupstats_build(struct cgroupstats
*stats
,
582 struct dentry
*dentry
)
587 #endif /* !CONFIG_CGROUPS */
589 #endif /* _LINUX_CGROUP_H */