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Tejun Heob4a04ab2015-05-13 15:38:40 -04001/*
2 * linux/cgroup-defs.h - basic definitions for cgroup
3 *
4 * This file provides basic type and interface. Include this file directly
5 * only if necessary to avoid cyclic dependencies.
6 */
7#ifndef _LINUX_CGROUP_DEFS_H
8#define _LINUX_CGROUP_DEFS_H
9
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>
Tejun Heo7d7efec2015-05-13 16:35:16 -040017#include <linux/percpu-rwsem.h>
Tejun Heob4a04ab2015-05-13 15:38:40 -040018#include <linux/workqueue.h>
19
20#ifdef CONFIG_CGROUPS
21
22struct cgroup;
23struct cgroup_root;
24struct cgroup_subsys;
25struct cgroup_taskset;
26struct kernfs_node;
27struct kernfs_ops;
28struct kernfs_open_file;
Arnd Bergmannc80ef9e2015-05-29 10:52:59 +020029struct seq_file;
Tejun Heob4a04ab2015-05-13 15:38:40 -040030
31#define MAX_CGROUP_TYPE_NAMELEN 32
32#define MAX_CGROUP_ROOT_NAMELEN 64
33#define MAX_CFTYPE_NAME 64
34
35/* define the enumeration of all cgroup subsystems */
36#define SUBSYS(_x) _x ## _cgrp_id,
37enum cgroup_subsys_id {
38#include <linux/cgroup_subsys.h>
39 CGROUP_SUBSYS_COUNT,
40};
41#undef SUBSYS
42
43/* bits in struct cgroup_subsys_state flags field */
44enum {
45 CSS_NO_REF = (1 << 0), /* no reference counting for this css */
46 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
47 CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
48};
49
50/* bits in struct cgroup flags field */
51enum {
52 /* Control Group requires release notifications to userspace */
53 CGRP_NOTIFY_ON_RELEASE,
54 /*
55 * Clone the parent's configuration when creating a new child
56 * cpuset cgroup. For historical reasons, this option can be
57 * specified at mount time and thus is implemented here.
58 */
59 CGRP_CPUSET_CLONE_CHILDREN,
60};
61
62/* cgroup_root->flags */
63enum {
64 CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
65 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
66 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
67};
68
69/* cftype->flags */
70enum {
71 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
72 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
73 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
74
75 /* internal flags, do not use outside cgroup core proper */
76 __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
77 __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
78};
79
80/*
81 * Per-subsystem/per-cgroup state maintained by the system. This is the
82 * fundamental structural building block that controllers deal with.
83 *
84 * Fields marked with "PI:" are public and immutable and may be accessed
85 * directly without synchronization.
86 */
87struct cgroup_subsys_state {
88 /* PI: the cgroup that this css is attached to */
89 struct cgroup *cgroup;
90
91 /* PI: the cgroup subsystem that this css is attached to */
92 struct cgroup_subsys *ss;
93
94 /* reference count - access via css_[try]get() and css_put() */
95 struct percpu_ref refcnt;
96
97 /* PI: the parent css */
98 struct cgroup_subsys_state *parent;
99
100 /* siblings list anchored at the parent's ->children */
101 struct list_head sibling;
102 struct list_head children;
103
104 /*
105 * PI: Subsys-unique ID. 0 is unused and root is always 1. The
106 * matching css can be looked up using css_from_id().
107 */
108 int id;
109
110 unsigned int flags;
111
112 /*
113 * Monotonically increasing unique serial number which defines a
114 * uniform order among all csses. It's guaranteed that all
115 * ->children lists are in the ascending order of ->serial_nr and
116 * used to allow interrupting and resuming iterations.
117 */
118 u64 serial_nr;
119
120 /* percpu_ref killing and RCU release */
121 struct rcu_head rcu_head;
122 struct work_struct destroy_work;
123};
124
125/*
126 * A css_set is a structure holding pointers to a set of
127 * cgroup_subsys_state objects. This saves space in the task struct
128 * object and speeds up fork()/exit(), since a single inc/dec and a
129 * list_add()/del() can bump the reference count on the entire cgroup
130 * set for a task.
131 */
132struct css_set {
133 /* Reference count */
134 atomic_t refcount;
135
136 /*
137 * List running through all cgroup groups in the same hash
138 * slot. Protected by css_set_lock
139 */
140 struct hlist_node hlist;
141
142 /*
143 * Lists running through all tasks using this cgroup group.
144 * mg_tasks lists tasks which belong to this cset but are in the
145 * process of being migrated out or in. Protected by
146 * css_set_rwsem, but, during migration, once tasks are moved to
147 * mg_tasks, it can be read safely while holding cgroup_mutex.
148 */
149 struct list_head tasks;
150 struct list_head mg_tasks;
151
152 /*
153 * List of cgrp_cset_links pointing at cgroups referenced from this
154 * css_set. Protected by css_set_lock.
155 */
156 struct list_head cgrp_links;
157
158 /* the default cgroup associated with this css_set */
159 struct cgroup *dfl_cgrp;
160
161 /*
162 * Set of subsystem states, one for each subsystem. This array is
163 * immutable after creation apart from the init_css_set during
164 * subsystem registration (at boot time).
165 */
166 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
167
168 /*
169 * List of csets participating in the on-going migration either as
170 * source or destination. Protected by cgroup_mutex.
171 */
172 struct list_head mg_preload_node;
173 struct list_head mg_node;
174
175 /*
176 * If this cset is acting as the source of migration the following
177 * two fields are set. mg_src_cgrp is the source cgroup of the
178 * on-going migration and mg_dst_cset is the destination cset the
179 * target tasks on this cset should be migrated to. Protected by
180 * cgroup_mutex.
181 */
182 struct cgroup *mg_src_cgrp;
183 struct css_set *mg_dst_cset;
184
185 /*
186 * On the default hierarhcy, ->subsys[ssid] may point to a css
187 * attached to an ancestor instead of the cgroup this css_set is
188 * associated with. The following node is anchored at
189 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
190 * iterate through all css's attached to a given cgroup.
191 */
192 struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
193
194 /* For RCU-protected deletion */
195 struct rcu_head rcu_head;
196};
197
198struct cgroup {
199 /* self css with NULL ->ss, points back to this cgroup */
200 struct cgroup_subsys_state self;
201
202 unsigned long flags; /* "unsigned long" so bitops work */
203
204 /*
205 * idr allocated in-hierarchy ID.
206 *
207 * ID 0 is not used, the ID of the root cgroup is always 1, and a
208 * new cgroup will be assigned with a smallest available ID.
209 *
210 * Allocating/Removing ID must be protected by cgroup_mutex.
211 */
212 int id;
213
214 /*
215 * If this cgroup contains any tasks, it contributes one to
216 * populated_cnt. All children with non-zero popuplated_cnt of
217 * their own contribute one. The count is zero iff there's no task
218 * in this cgroup or its subtree.
219 */
220 int populated_cnt;
221
222 struct kernfs_node *kn; /* cgroup kernfs entry */
Tejun Heo187fe842015-06-18 16:54:28 -0400223 struct kernfs_node *procs_kn; /* kn for "cgroup.procs" */
Tejun Heob4a04ab2015-05-13 15:38:40 -0400224 struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
225
226 /*
227 * The bitmask of subsystems enabled on the child cgroups.
228 * ->subtree_control is the one configured through
229 * "cgroup.subtree_control" while ->child_subsys_mask is the
230 * effective one which may have more subsystems enabled.
231 * Controller knobs are made available iff it's enabled in
232 * ->subtree_control.
233 */
234 unsigned int subtree_control;
235 unsigned int child_subsys_mask;
236
237 /* Private pointers for each registered subsystem */
238 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
239
240 struct cgroup_root *root;
241
242 /*
243 * List of cgrp_cset_links pointing at css_sets with tasks in this
244 * cgroup. Protected by css_set_lock.
245 */
246 struct list_head cset_links;
247
248 /*
249 * On the default hierarchy, a css_set for a cgroup with some
250 * susbsys disabled will point to css's which are associated with
251 * the closest ancestor which has the subsys enabled. The
252 * following lists all css_sets which point to this cgroup's css
253 * for the given subsystem.
254 */
255 struct list_head e_csets[CGROUP_SUBSYS_COUNT];
256
257 /*
258 * list of pidlists, up to two for each namespace (one for procs, one
259 * for tasks); created on demand.
260 */
261 struct list_head pidlists;
262 struct mutex pidlist_mutex;
263
264 /* used to wait for offlining of csses */
265 wait_queue_head_t offline_waitq;
266
267 /* used to schedule release agent */
268 struct work_struct release_agent_work;
269};
270
271/*
272 * A cgroup_root represents the root of a cgroup hierarchy, and may be
273 * associated with a kernfs_root to form an active hierarchy. This is
274 * internal to cgroup core. Don't access directly from controllers.
275 */
276struct cgroup_root {
277 struct kernfs_root *kf_root;
278
279 /* The bitmask of subsystems attached to this hierarchy */
280 unsigned int subsys_mask;
281
282 /* Unique id for this hierarchy. */
283 int hierarchy_id;
284
285 /* The root cgroup. Root is destroyed on its release. */
286 struct cgroup cgrp;
287
288 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
289 atomic_t nr_cgrps;
290
291 /* A list running through the active hierarchies */
292 struct list_head root_list;
293
294 /* Hierarchy-specific flags */
295 unsigned int flags;
296
297 /* IDs for cgroups in this hierarchy */
298 struct idr cgroup_idr;
299
300 /* The path to use for release notifications. */
301 char release_agent_path[PATH_MAX];
302
303 /* The name for this hierarchy - may be empty */
304 char name[MAX_CGROUP_ROOT_NAMELEN];
305};
306
307/*
308 * struct cftype: handler definitions for cgroup control files
309 *
310 * When reading/writing to a file:
311 * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
312 * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
313 */
314struct cftype {
315 /*
316 * By convention, the name should begin with the name of the
317 * subsystem, followed by a period. Zero length string indicates
318 * end of cftype array.
319 */
320 char name[MAX_CFTYPE_NAME];
321 int private;
322 /*
323 * If not 0, file mode is set to this value, otherwise it will
324 * be figured out automatically
325 */
326 umode_t mode;
327
328 /*
329 * The maximum length of string, excluding trailing nul, that can
330 * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
331 */
332 size_t max_write_len;
333
334 /* CFTYPE_* flags */
335 unsigned int flags;
336
337 /*
338 * Fields used for internal bookkeeping. Initialized automatically
339 * during registration.
340 */
341 struct cgroup_subsys *ss; /* NULL for cgroup core files */
342 struct list_head node; /* anchored at ss->cfts */
343 struct kernfs_ops *kf_ops;
344
345 /*
346 * read_u64() is a shortcut for the common case of returning a
347 * single integer. Use it in place of read()
348 */
349 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
350 /*
351 * read_s64() is a signed version of read_u64()
352 */
353 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
354
355 /* generic seq_file read interface */
356 int (*seq_show)(struct seq_file *sf, void *v);
357
358 /* optional ops, implement all or none */
359 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
360 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
361 void (*seq_stop)(struct seq_file *sf, void *v);
362
363 /*
364 * write_u64() is a shortcut for the common case of accepting
365 * a single integer (as parsed by simple_strtoull) from
366 * userspace. Use in place of write(); return 0 or error.
367 */
368 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
369 u64 val);
370 /*
371 * write_s64() is a signed version of write_u64()
372 */
373 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
374 s64 val);
375
376 /*
377 * write() is the generic write callback which maps directly to
378 * kernfs write operation and overrides all other operations.
379 * Maximum write size is determined by ->max_write_len. Use
380 * of_css/cft() to access the associated css and cft.
381 */
382 ssize_t (*write)(struct kernfs_open_file *of,
383 char *buf, size_t nbytes, loff_t off);
384
385#ifdef CONFIG_DEBUG_LOCK_ALLOC
386 struct lock_class_key lockdep_key;
387#endif
388};
389
390/*
391 * Control Group subsystem type.
392 * See Documentation/cgroups/cgroups.txt for details
393 */
394struct cgroup_subsys {
395 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
396 int (*css_online)(struct cgroup_subsys_state *css);
397 void (*css_offline)(struct cgroup_subsys_state *css);
398 void (*css_released)(struct cgroup_subsys_state *css);
399 void (*css_free)(struct cgroup_subsys_state *css);
400 void (*css_reset)(struct cgroup_subsys_state *css);
401 void (*css_e_css_changed)(struct cgroup_subsys_state *css);
402
403 int (*can_attach)(struct cgroup_subsys_state *css,
404 struct cgroup_taskset *tset);
405 void (*cancel_attach)(struct cgroup_subsys_state *css,
406 struct cgroup_taskset *tset);
407 void (*attach)(struct cgroup_subsys_state *css,
408 struct cgroup_taskset *tset);
409 void (*fork)(struct task_struct *task);
410 void (*exit)(struct cgroup_subsys_state *css,
411 struct cgroup_subsys_state *old_css,
412 struct task_struct *task);
413 void (*bind)(struct cgroup_subsys_state *root_css);
414
415 int disabled;
416 int early_init;
417
418 /*
419 * If %false, this subsystem is properly hierarchical -
420 * configuration, resource accounting and restriction on a parent
421 * cgroup cover those of its children. If %true, hierarchy support
422 * is broken in some ways - some subsystems ignore hierarchy
423 * completely while others are only implemented half-way.
424 *
425 * It's now disallowed to create nested cgroups if the subsystem is
426 * broken and cgroup core will emit a warning message on such
427 * cases. Eventually, all subsystems will be made properly
428 * hierarchical and this will go away.
429 */
430 bool broken_hierarchy;
431 bool warned_broken_hierarchy;
432
433 /* the following two fields are initialized automtically during boot */
434 int id;
435 const char *name;
436
437 /* link to parent, protected by cgroup_lock() */
438 struct cgroup_root *root;
439
440 /* idr for css->id */
441 struct idr css_idr;
442
443 /*
444 * List of cftypes. Each entry is the first entry of an array
445 * terminated by zero length name.
446 */
447 struct list_head cfts;
448
449 /*
450 * Base cftypes which are automatically registered. The two can
451 * point to the same array.
452 */
453 struct cftype *dfl_cftypes; /* for the default hierarchy */
454 struct cftype *legacy_cftypes; /* for the legacy hierarchies */
455
456 /*
457 * A subsystem may depend on other subsystems. When such subsystem
458 * is enabled on a cgroup, the depended-upon subsystems are enabled
459 * together if available. Subsystems enabled due to dependency are
460 * not visible to userland until explicitly enabled. The following
461 * specifies the mask of subsystems that this one depends on.
462 */
463 unsigned int depends_on;
464};
465
Tejun Heod59cfc02015-05-13 16:35:17 -0400466extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
467
468/**
469 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
470 * @tsk: target task
471 *
472 * Called from threadgroup_change_begin() and allows cgroup operations to
473 * synchronize against threadgroup changes using a percpu_rw_semaphore.
474 */
475static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
476{
477 percpu_down_read(&cgroup_threadgroup_rwsem);
478}
479
480/**
481 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
482 * @tsk: target task
483 *
484 * Called from threadgroup_change_end(). Counterpart of
485 * cgroup_threadcgroup_change_begin().
486 */
487static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
488{
489 percpu_up_read(&cgroup_threadgroup_rwsem);
490}
Tejun Heo7d7efec2015-05-13 16:35:16 -0400491
492#else /* CONFIG_CGROUPS */
493
Aleksa Saraicb4a3162015-06-06 10:02:14 +1000494#define CGROUP_SUBSYS_COUNT 0
495
Tejun Heo7d7efec2015-05-13 16:35:16 -0400496static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
497static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
498
Tejun Heob4a04ab2015-05-13 15:38:40 -0400499#endif /* CONFIG_CGROUPS */
Tejun Heo7d7efec2015-05-13 16:35:16 -0400500
Tejun Heob4a04ab2015-05-13 15:38:40 -0400501#endif /* _LINUX_CGROUP_DEFS_H */