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>
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);
38 extern struct file_operations proc_cgroup_operations;
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>
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;
55 /* State maintained by the cgroup system to allow
56 * subsystems to be "busy". Should be accessed via css_get()
64 /* bits in struct cgroup_subsys_state flags field */
66 CSS_ROOT, /* This CSS is the root of the subsystem */
70 * Call css_get() to hold a reference on the cgroup;
74 static inline void css_get(struct cgroup_subsys_state *css)
76 /* We don't need to reference count the root state */
77 if (!test_bit(CSS_ROOT, &css->flags))
78 atomic_inc(&css->refcnt);
81 * css_put() should be called to release a reference taken by
85 extern void __css_put(struct cgroup_subsys_state *css);
86 static inline void css_put(struct cgroup_subsys_state *css)
88 if (!test_bit(CSS_ROOT, &css->flags))
92 /* bits in struct cgroup flags field */
94 /* Control Group is dead */
96 /* Control Group has previously had a child cgroup or a task,
97 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) */
99 /* Control Group requires release notifications to userspace */
100 CGRP_NOTIFY_ON_RELEASE,
104 unsigned long flags; /* "unsigned long" so bitops work */
106 /* count users of this cgroup. >0 means busy, but doesn't
107 * necessarily indicate the number of tasks in the
112 * We link our 'sibling' struct into our parent's 'children'.
113 * Our children link their 'sibling' into our 'children'.
115 struct list_head sibling; /* my parent's children */
116 struct list_head children; /* my children */
118 struct cgroup *parent; /* my parent */
119 struct dentry *dentry; /* cgroup fs entry, RCU protected */
121 /* Private pointers for each registered subsystem */
122 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
124 struct cgroupfs_root *root;
125 struct cgroup *top_cgroup;
128 * List of cg_cgroup_links pointing at css_sets with
129 * tasks in this cgroup. Protected by css_set_lock
131 struct list_head css_sets;
134 * Linked list running through all cgroups that can
135 * potentially be reaped by the release agent. Protected by
138 struct list_head release_list;
140 /* pids_mutex protects the fields below */
141 struct rw_semaphore pids_mutex;
142 /* Array of process ids in the cgroup */
144 /* How many files are using the current tasks_pids array */
146 /* Length of the current tasks_pids array */
149 /* For RCU-protected deletion */
150 struct rcu_head rcu_head;
153 /* A css_set is a structure holding pointers to a set of
154 * cgroup_subsys_state objects. This saves space in the task struct
155 * object and speeds up fork()/exit(), since a single inc/dec and a
156 * list_add()/del() can bump the reference count on the entire
157 * cgroup set for a task.
162 /* Reference count */
166 * List running through all cgroup groups in the same hash
167 * slot. Protected by css_set_lock
169 struct hlist_node hlist;
172 * List running through all tasks using this cgroup
173 * group. Protected by css_set_lock
175 struct list_head tasks;
178 * List of cg_cgroup_link objects on link chains from
179 * cgroups referenced from this css_set. Protected by
182 struct list_head cg_links;
185 * Set of subsystem states, one for each subsystem. This array
186 * is immutable after creation apart from the init_css_set
187 * during subsystem registration (at boot time).
189 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
193 * cgroup_map_cb is an abstract callback API for reporting map-valued
197 struct cgroup_map_cb {
198 int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value);
204 * The files in the cgroup filesystem mostly have a very simple read/write
205 * handling, some common function will take care of it. Nevertheless some cases
206 * (read tasks) are special and therefore I define this structure for every
210 * When reading/writing to a file:
211 * - the cgroup to use is file->f_dentry->d_parent->d_fsdata
212 * - the 'cftype' of the file is file->f_dentry->d_fsdata
215 #define MAX_CFTYPE_NAME 64
217 /* By convention, the name should begin with the name of the
218 * subsystem, followed by a period */
219 char name[MAX_CFTYPE_NAME];
223 * If non-zero, defines the maximum length of string that can
224 * be passed to write_string; defaults to 64
226 size_t max_write_len;
228 int (*open)(struct inode *inode, struct file *file);
229 ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
231 char __user *buf, size_t nbytes, loff_t *ppos);
233 * read_u64() is a shortcut for the common case of returning a
234 * single integer. Use it in place of read()
236 u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft);
238 * read_s64() is a signed version of read_u64()
240 s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft);
242 * read_map() is used for defining a map of key/value
243 * pairs. It should call cb->fill(cb, key, value) for each
244 * entry. The key/value pairs (and their ordering) should not
245 * change between reboots.
247 int (*read_map)(struct cgroup *cont, struct cftype *cft,
248 struct cgroup_map_cb *cb);
250 * read_seq_string() is used for outputting a simple sequence
253 int (*read_seq_string)(struct cgroup *cont, struct cftype *cft,
256 ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft,
258 const char __user *buf, size_t nbytes, loff_t *ppos);
261 * write_u64() is a shortcut for the common case of accepting
262 * a single integer (as parsed by simple_strtoull) from
263 * userspace. Use in place of write(); return 0 or error.
265 int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val);
267 * write_s64() is a signed version of write_u64()
269 int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val);
272 * write_string() is passed a nul-terminated kernelspace
273 * buffer of maximum length determined by max_write_len.
274 * Returns 0 or -ve error code.
276 int (*write_string)(struct cgroup *cgrp, struct cftype *cft,
279 * trigger() callback can be used to get some kick from the
280 * userspace, when the actual string written is not important
281 * at all. The private field can be used to determine the
282 * kick type for multiplexing.
284 int (*trigger)(struct cgroup *cgrp, unsigned int event);
286 int (*release)(struct inode *inode, struct file *file);
289 struct cgroup_scanner {
291 int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
292 void (*process_task)(struct task_struct *p,
293 struct cgroup_scanner *scan);
294 struct ptr_heap *heap;
297 /* Add a new file to the given cgroup directory. Should only be
298 * called by subsystems from within a populate() method */
299 int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
300 const struct cftype *cft);
302 /* Add a set of new files to the given cgroup directory. Should
303 * only be called by subsystems from within a populate() method */
304 int cgroup_add_files(struct cgroup *cgrp,
305 struct cgroup_subsys *subsys,
306 const struct cftype cft[],
309 int cgroup_is_removed(const struct cgroup *cgrp);
311 int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
313 int cgroup_task_count(const struct cgroup *cgrp);
315 /* Return true if the cgroup is a descendant of the current cgroup */
316 int cgroup_is_descendant(const struct cgroup *cgrp);
318 /* Control Group subsystem type. See Documentation/cgroups.txt for details */
320 struct cgroup_subsys {
321 struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
322 struct cgroup *cgrp);
323 void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
324 void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
325 int (*can_attach)(struct cgroup_subsys *ss,
326 struct cgroup *cgrp, struct task_struct *tsk);
327 void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
328 struct cgroup *old_cgrp, struct task_struct *tsk);
329 void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
330 void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
331 int (*populate)(struct cgroup_subsys *ss,
332 struct cgroup *cgrp);
333 void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
334 void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
340 #define MAX_CGROUP_TYPE_NAMELEN 32
343 struct cgroupfs_root *root;
345 struct list_head sibling;
348 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
349 #include <linux/cgroup_subsys.h>
352 static inline struct cgroup_subsys_state *cgroup_subsys_state(
353 struct cgroup *cgrp, int subsys_id)
355 return cgrp->subsys[subsys_id];
358 static inline struct cgroup_subsys_state *task_subsys_state(
359 struct task_struct *task, int subsys_id)
361 return rcu_dereference(task->cgroups->subsys[subsys_id]);
364 static inline struct cgroup* task_cgroup(struct task_struct *task,
367 return task_subsys_state(task, subsys_id)->cgroup;
370 int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss,
373 /* A cgroup_iter should be treated as an opaque object */
375 struct list_head *cg_link;
376 struct list_head *task;
379 /* To iterate across the tasks in a cgroup:
381 * 1) call cgroup_iter_start to intialize an iterator
383 * 2) call cgroup_iter_next() to retrieve member tasks until it
384 * returns NULL or until you want to end the iteration
386 * 3) call cgroup_iter_end() to destroy the iterator.
388 * Or, call cgroup_scan_tasks() to iterate through every task in a cpuset.
389 * - cgroup_scan_tasks() holds the css_set_lock when calling the test_task()
390 * callback, but not while calling the process_task() callback.
392 void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
393 struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
394 struct cgroup_iter *it);
395 void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
396 int cgroup_scan_tasks(struct cgroup_scanner *scan);
397 int cgroup_attach_task(struct cgroup *, struct task_struct *);
399 #else /* !CONFIG_CGROUPS */
401 static inline int cgroup_init_early(void) { return 0; }
402 static inline int cgroup_init(void) { return 0; }
403 static inline void cgroup_fork(struct task_struct *p) {}
404 static inline void cgroup_fork_callbacks(struct task_struct *p) {}
405 static inline void cgroup_post_fork(struct task_struct *p) {}
406 static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
408 static inline void cgroup_lock(void) {}
409 static inline void cgroup_unlock(void) {}
410 static inline int cgroupstats_build(struct cgroupstats *stats,
411 struct dentry *dentry)
416 #endif /* !CONFIG_CGROUPS */
418 #endif /* _LINUX_CGROUP_H */