2 * linux/cgroup-defs.h - basic definitions for cgroup
4 * This file provides basic type and interface. Include this file directly
5 * only if necessary to avoid cyclic dependencies.
7 #ifndef _LINUX_CGROUP_DEFS_H
8 #define _LINUX_CGROUP_DEFS_H
10 #include <linux/limits.h>
11 #include <linux/list.h>
12 #include <linux/idr.h>
13 #include <linux/wait.h>
14 #include <linux/mutex.h>
15 #include <linux/rcupdate.h>
16 #include <linux/percpu-refcount.h>
17 #include <linux/percpu-rwsem.h>
18 #include <linux/workqueue.h>
25 struct cgroup_taskset;
28 struct kernfs_open_file;
31 #define MAX_CGROUP_TYPE_NAMELEN 32
32 #define MAX_CGROUP_ROOT_NAMELEN 64
33 #define MAX_CFTYPE_NAME 64
35 /* define the enumeration of all cgroup subsystems */
36 #define SUBSYS(_x) _x ## _cgrp_id,
37 #define SUBSYS_TAG(_t) CGROUP_ ## _t, \
38 __unused_tag_ ## _t = CGROUP_ ## _t - 1,
39 enum cgroup_subsys_id {
40 #include <linux/cgroup_subsys.h>
46 #define CGROUP_CANFORK_COUNT (CGROUP_CANFORK_END - CGROUP_CANFORK_START)
48 /* bits in struct cgroup_subsys_state flags field */
50 CSS_NO_REF = (1 << 0), /* no reference counting for this css */
51 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
52 CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
55 /* bits in struct cgroup flags field */
57 /* Control Group requires release notifications to userspace */
58 CGRP_NOTIFY_ON_RELEASE,
60 * Clone the parent's configuration when creating a new child
61 * cpuset cgroup. For historical reasons, this option can be
62 * specified at mount time and thus is implemented here.
64 CGRP_CPUSET_CLONE_CHILDREN,
67 /* cgroup_root->flags */
69 CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
70 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
71 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
76 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
77 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
78 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
80 /* internal flags, do not use outside cgroup core proper */
81 __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
82 __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
86 * Per-subsystem/per-cgroup state maintained by the system. This is the
87 * fundamental structural building block that controllers deal with.
89 * Fields marked with "PI:" are public and immutable and may be accessed
90 * directly without synchronization.
92 struct cgroup_subsys_state {
93 /* PI: the cgroup that this css is attached to */
94 struct cgroup *cgroup;
96 /* PI: the cgroup subsystem that this css is attached to */
97 struct cgroup_subsys *ss;
99 /* reference count - access via css_[try]get() and css_put() */
100 struct percpu_ref refcnt;
102 /* PI: the parent css */
103 struct cgroup_subsys_state *parent;
105 /* siblings list anchored at the parent's ->children */
106 struct list_head sibling;
107 struct list_head children;
110 * PI: Subsys-unique ID. 0 is unused and root is always 1. The
111 * matching css can be looked up using css_from_id().
118 * Monotonically increasing unique serial number which defines a
119 * uniform order among all csses. It's guaranteed that all
120 * ->children lists are in the ascending order of ->serial_nr and
121 * used to allow interrupting and resuming iterations.
125 /* percpu_ref killing and RCU release */
126 struct rcu_head rcu_head;
127 struct work_struct destroy_work;
131 * A css_set is a structure holding pointers to a set of
132 * cgroup_subsys_state objects. This saves space in the task struct
133 * object and speeds up fork()/exit(), since a single inc/dec and a
134 * list_add()/del() can bump the reference count on the entire cgroup
138 /* Reference count */
142 * List running through all cgroup groups in the same hash
143 * slot. Protected by css_set_lock
145 struct hlist_node hlist;
148 * Lists running through all tasks using this cgroup group.
149 * mg_tasks lists tasks which belong to this cset but are in the
150 * process of being migrated out or in. Protected by
151 * css_set_rwsem, but, during migration, once tasks are moved to
152 * mg_tasks, it can be read safely while holding cgroup_mutex.
154 struct list_head tasks;
155 struct list_head mg_tasks;
158 * List of cgrp_cset_links pointing at cgroups referenced from this
159 * css_set. Protected by css_set_lock.
161 struct list_head cgrp_links;
163 /* the default cgroup associated with this css_set */
164 struct cgroup *dfl_cgrp;
167 * Set of subsystem states, one for each subsystem. This array is
168 * immutable after creation apart from the init_css_set during
169 * subsystem registration (at boot time).
171 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
174 * List of csets participating in the on-going migration either as
175 * source or destination. Protected by cgroup_mutex.
177 struct list_head mg_preload_node;
178 struct list_head mg_node;
181 * If this cset is acting as the source of migration the following
182 * two fields are set. mg_src_cgrp is the source cgroup of the
183 * on-going migration and mg_dst_cset is the destination cset the
184 * target tasks on this cset should be migrated to. Protected by
187 struct cgroup *mg_src_cgrp;
188 struct css_set *mg_dst_cset;
191 * On the default hierarhcy, ->subsys[ssid] may point to a css
192 * attached to an ancestor instead of the cgroup this css_set is
193 * associated with. The following node is anchored at
194 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
195 * iterate through all css's attached to a given cgroup.
197 struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
199 /* For RCU-protected deletion */
200 struct rcu_head rcu_head;
204 /* self css with NULL ->ss, points back to this cgroup */
205 struct cgroup_subsys_state self;
207 unsigned long flags; /* "unsigned long" so bitops work */
210 * idr allocated in-hierarchy ID.
212 * ID 0 is not used, the ID of the root cgroup is always 1, and a
213 * new cgroup will be assigned with a smallest available ID.
215 * Allocating/Removing ID must be protected by cgroup_mutex.
220 * If this cgroup contains any tasks, it contributes one to
221 * populated_cnt. All children with non-zero popuplated_cnt of
222 * their own contribute one. The count is zero iff there's no task
223 * in this cgroup or its subtree.
227 struct kernfs_node *kn; /* cgroup kernfs entry */
228 struct kernfs_node *procs_kn; /* kn for "cgroup.procs" */
229 struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
232 * The bitmask of subsystems enabled on the child cgroups.
233 * ->subtree_control is the one configured through
234 * "cgroup.subtree_control" while ->child_subsys_mask is the
235 * effective one which may have more subsystems enabled.
236 * Controller knobs are made available iff it's enabled in
239 unsigned int subtree_control;
240 unsigned int child_subsys_mask;
242 /* Private pointers for each registered subsystem */
243 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
245 struct cgroup_root *root;
248 * List of cgrp_cset_links pointing at css_sets with tasks in this
249 * cgroup. Protected by css_set_lock.
251 struct list_head cset_links;
254 * On the default hierarchy, a css_set for a cgroup with some
255 * susbsys disabled will point to css's which are associated with
256 * the closest ancestor which has the subsys enabled. The
257 * following lists all css_sets which point to this cgroup's css
258 * for the given subsystem.
260 struct list_head e_csets[CGROUP_SUBSYS_COUNT];
263 * list of pidlists, up to two for each namespace (one for procs, one
264 * for tasks); created on demand.
266 struct list_head pidlists;
267 struct mutex pidlist_mutex;
269 /* used to wait for offlining of csses */
270 wait_queue_head_t offline_waitq;
272 /* used to schedule release agent */
273 struct work_struct release_agent_work;
277 * A cgroup_root represents the root of a cgroup hierarchy, and may be
278 * associated with a kernfs_root to form an active hierarchy. This is
279 * internal to cgroup core. Don't access directly from controllers.
282 struct kernfs_root *kf_root;
284 /* The bitmask of subsystems attached to this hierarchy */
285 unsigned int subsys_mask;
287 /* Unique id for this hierarchy. */
290 /* The root cgroup. Root is destroyed on its release. */
293 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
296 /* A list running through the active hierarchies */
297 struct list_head root_list;
299 /* Hierarchy-specific flags */
302 /* IDs for cgroups in this hierarchy */
303 struct idr cgroup_idr;
305 /* The path to use for release notifications. */
306 char release_agent_path[PATH_MAX];
308 /* The name for this hierarchy - may be empty */
309 char name[MAX_CGROUP_ROOT_NAMELEN];
313 * struct cftype: handler definitions for cgroup control files
315 * When reading/writing to a file:
316 * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
317 * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
321 * By convention, the name should begin with the name of the
322 * subsystem, followed by a period. Zero length string indicates
323 * end of cftype array.
325 char name[MAX_CFTYPE_NAME];
326 unsigned long private;
328 * If not 0, file mode is set to this value, otherwise it will
329 * be figured out automatically
334 * The maximum length of string, excluding trailing nul, that can
335 * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
337 size_t max_write_len;
343 * Fields used for internal bookkeeping. Initialized automatically
344 * during registration.
346 struct cgroup_subsys *ss; /* NULL for cgroup core files */
347 struct list_head node; /* anchored at ss->cfts */
348 struct kernfs_ops *kf_ops;
351 * read_u64() is a shortcut for the common case of returning a
352 * single integer. Use it in place of read()
354 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
356 * read_s64() is a signed version of read_u64()
358 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
360 /* generic seq_file read interface */
361 int (*seq_show)(struct seq_file *sf, void *v);
363 /* optional ops, implement all or none */
364 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
365 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
366 void (*seq_stop)(struct seq_file *sf, void *v);
369 * write_u64() is a shortcut for the common case of accepting
370 * a single integer (as parsed by simple_strtoull) from
371 * userspace. Use in place of write(); return 0 or error.
373 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
376 * write_s64() is a signed version of write_u64()
378 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
382 * write() is the generic write callback which maps directly to
383 * kernfs write operation and overrides all other operations.
384 * Maximum write size is determined by ->max_write_len. Use
385 * of_css/cft() to access the associated css and cft.
387 ssize_t (*write)(struct kernfs_open_file *of,
388 char *buf, size_t nbytes, loff_t off);
390 #ifdef CONFIG_DEBUG_LOCK_ALLOC
391 struct lock_class_key lockdep_key;
396 * Control Group subsystem type.
397 * See Documentation/cgroups/cgroups.txt for details
399 struct cgroup_subsys {
400 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
401 int (*css_online)(struct cgroup_subsys_state *css);
402 void (*css_offline)(struct cgroup_subsys_state *css);
403 void (*css_released)(struct cgroup_subsys_state *css);
404 void (*css_free)(struct cgroup_subsys_state *css);
405 void (*css_reset)(struct cgroup_subsys_state *css);
406 void (*css_e_css_changed)(struct cgroup_subsys_state *css);
408 int (*can_attach)(struct cgroup_subsys_state *css,
409 struct cgroup_taskset *tset);
410 void (*cancel_attach)(struct cgroup_subsys_state *css,
411 struct cgroup_taskset *tset);
412 void (*attach)(struct cgroup_subsys_state *css,
413 struct cgroup_taskset *tset);
414 int (*can_fork)(struct task_struct *task, void **priv_p);
415 void (*cancel_fork)(struct task_struct *task, void *priv);
416 void (*fork)(struct task_struct *task, void *priv);
417 void (*exit)(struct cgroup_subsys_state *css,
418 struct cgroup_subsys_state *old_css,
419 struct task_struct *task);
420 void (*bind)(struct cgroup_subsys_state *root_css);
426 * If %false, this subsystem is properly hierarchical -
427 * configuration, resource accounting and restriction on a parent
428 * cgroup cover those of its children. If %true, hierarchy support
429 * is broken in some ways - some subsystems ignore hierarchy
430 * completely while others are only implemented half-way.
432 * It's now disallowed to create nested cgroups if the subsystem is
433 * broken and cgroup core will emit a warning message on such
434 * cases. Eventually, all subsystems will be made properly
435 * hierarchical and this will go away.
437 bool broken_hierarchy;
438 bool warned_broken_hierarchy;
440 /* the following two fields are initialized automtically during boot */
444 /* optional, initialized automatically during boot if not set */
445 const char *legacy_name;
447 /* link to parent, protected by cgroup_lock() */
448 struct cgroup_root *root;
450 /* idr for css->id */
454 * List of cftypes. Each entry is the first entry of an array
455 * terminated by zero length name.
457 struct list_head cfts;
460 * Base cftypes which are automatically registered. The two can
461 * point to the same array.
463 struct cftype *dfl_cftypes; /* for the default hierarchy */
464 struct cftype *legacy_cftypes; /* for the legacy hierarchies */
467 * A subsystem may depend on other subsystems. When such subsystem
468 * is enabled on a cgroup, the depended-upon subsystems are enabled
469 * together if available. Subsystems enabled due to dependency are
470 * not visible to userland until explicitly enabled. The following
471 * specifies the mask of subsystems that this one depends on.
473 unsigned int depends_on;
476 void cgroup_threadgroup_change_begin(struct task_struct *tsk);
477 void cgroup_threadgroup_change_end(struct task_struct *tsk);
479 #else /* CONFIG_CGROUPS */
481 #define CGROUP_CANFORK_COUNT 0
482 #define CGROUP_SUBSYS_COUNT 0
484 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
485 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
487 #endif /* CONFIG_CGROUPS */
489 #endif /* _LINUX_CGROUP_DEFS_H */