1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * linux/cgroup-defs.h - basic definitions for cgroup
4 *
5 * This file provides basic type and interface. Include this file directly
6 * only if necessary to avoid cyclic dependencies.
7 */
8 #ifndef _LINUX_CGROUP_DEFS_H
9 #define _LINUX_CGROUP_DEFS_H
10
11 #include <linux/limits.h>
12 #include <linux/list.h>
13 #include <linux/idr.h>
14 #include <linux/wait.h>
15 #include <linux/mutex.h>
16 #include <linux/rcupdate.h>
17 #include <linux/refcount.h>
18 #include <linux/percpu-refcount.h>
19 #include <linux/percpu-rwsem.h>
20 #include <linux/u64_stats_sync.h>
21 #include <linux/workqueue.h>
22 #include <linux/bpf-cgroup-defs.h>
23 #include <linux/psi_types.h>
24
25 #ifdef CONFIG_CGROUPS
26
27 struct cgroup;
28 struct cgroup_root;
29 struct cgroup_subsys;
30 struct cgroup_taskset;
31 struct kernfs_node;
32 struct kernfs_ops;
33 struct kernfs_open_file;
34 struct seq_file;
35 struct poll_table_struct;
36
37 #define MAX_CGROUP_TYPE_NAMELEN 32
38 #define MAX_CGROUP_ROOT_NAMELEN 64
39 #define MAX_CFTYPE_NAME 64
40
41 /* define the enumeration of all cgroup subsystems */
42 #define SUBSYS(_x) _x ## _cgrp_id,
43 enum cgroup_subsys_id {
44 #include <linux/cgroup_subsys.h>
45 CGROUP_SUBSYS_COUNT,
46 };
47 #undef SUBSYS
48
49 /* bits in struct cgroup_subsys_state flags field */
50 enum {
51 CSS_NO_REF = (1 << 0), /* no reference counting for this css */
52 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
53 CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
54 CSS_VISIBLE = (1 << 3), /* css is visible to userland */
55 CSS_DYING = (1 << 4), /* css is dying */
56 };
57
58 /* bits in struct cgroup flags field */
59 enum {
60 /* Control Group requires release notifications to userspace */
61 CGRP_NOTIFY_ON_RELEASE,
62 /*
63 * Clone the parent's configuration when creating a new child
64 * cpuset cgroup. For historical reasons, this option can be
65 * specified at mount time and thus is implemented here.
66 */
67 CGRP_CPUSET_CLONE_CHILDREN,
68
69 /* Control group has to be frozen. */
70 CGRP_FREEZE,
71
72 /* Cgroup is frozen. */
73 CGRP_FROZEN,
74
75 /* Control group has to be killed. */
76 CGRP_KILL,
77 };
78
79 /* cgroup_root->flags */
80 enum {
81 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
82 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
83
84 /*
85 * Consider namespaces as delegation boundaries. If this flag is
86 * set, controller specific interface files in a namespace root
87 * aren't writeable from inside the namespace.
88 */
89 CGRP_ROOT_NS_DELEGATE = (1 << 3),
90
91 /*
92 * Reduce latencies on dynamic cgroup modifications such as task
93 * migrations and controller on/offs by disabling percpu operation on
94 * cgroup_threadgroup_rwsem. This makes hot path operations such as
95 * forks and exits into the slow path and more expensive.
96 *
97 * The static usage pattern of creating a cgroup, enabling controllers,
98 * and then seeding it with CLONE_INTO_CGROUP doesn't require write
99 * locking cgroup_threadgroup_rwsem and thus doesn't benefit from
100 * favordynmod.
101 */
102 CGRP_ROOT_FAVOR_DYNMODS = (1 << 4),
103
104 /*
105 * Enable cpuset controller in v1 cgroup to use v2 behavior.
106 */
107 CGRP_ROOT_CPUSET_V2_MODE = (1 << 16),
108
109 /*
110 * Enable legacy local memory.events.
111 */
112 CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 17),
113
114 /*
115 * Enable recursive subtree protection
116 */
117 CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 18),
118
119 /*
120 * Enable hugetlb accounting for the memory controller.
121 */
122 CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING = (1 << 19),
123
124 /*
125 * Enable legacy local pids.events.
126 */
127 CGRP_ROOT_PIDS_LOCAL_EVENTS = (1 << 20),
128 };
129
130 /* cftype->flags */
131 enum {
132 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
133 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
134 CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */
135
136 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
137 CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
138 CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */
139
140 /* internal flags, do not use outside cgroup core proper */
141 __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
142 __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
143 __CFTYPE_ADDED = (1 << 18),
144 };
145
146 /*
147 * cgroup_file is the handle for a file instance created in a cgroup which
148 * is used, for example, to generate file changed notifications. This can
149 * be obtained by setting cftype->file_offset.
150 */
151 struct cgroup_file {
152 /* do not access any fields from outside cgroup core */
153 struct kernfs_node *kn;
154 unsigned long notified_at;
155 struct timer_list notify_timer;
156 };
157
158 /*
159 * Per-subsystem/per-cgroup state maintained by the system. This is the
160 * fundamental structural building block that controllers deal with.
161 *
162 * Fields marked with "PI:" are public and immutable and may be accessed
163 * directly without synchronization.
164 */
165 struct cgroup_subsys_state {
166 /* PI: the cgroup that this css is attached to */
167 struct cgroup *cgroup;
168
169 /* PI: the cgroup subsystem that this css is attached to */
170 struct cgroup_subsys *ss;
171
172 /* reference count - access via css_[try]get() and css_put() */
173 struct percpu_ref refcnt;
174
175 /* siblings list anchored at the parent's ->children */
176 struct list_head sibling;
177 struct list_head children;
178
179 /* flush target list anchored at cgrp->rstat_css_list */
180 struct list_head rstat_css_node;
181
182 /*
183 * PI: Subsys-unique ID. 0 is unused and root is always 1. The
184 * matching css can be looked up using css_from_id().
185 */
186 int id;
187
188 unsigned int flags;
189
190 /*
191 * Monotonically increasing unique serial number which defines a
192 * uniform order among all csses. It's guaranteed that all
193 * ->children lists are in the ascending order of ->serial_nr and
194 * used to allow interrupting and resuming iterations.
195 */
196 u64 serial_nr;
197
198 /*
199 * Incremented by online self and children. Used to guarantee that
200 * parents are not offlined before their children.
201 */
202 atomic_t online_cnt;
203
204 /* percpu_ref killing and RCU release */
205 struct work_struct destroy_work;
206 struct rcu_work destroy_rwork;
207
208 /*
209 * PI: the parent css. Placed here for cache proximity to following
210 * fields of the containing structure.
211 */
212 struct cgroup_subsys_state *parent;
213 };
214
215 /*
216 * A css_set is a structure holding pointers to a set of
217 * cgroup_subsys_state objects. This saves space in the task struct
218 * object and speeds up fork()/exit(), since a single inc/dec and a
219 * list_add()/del() can bump the reference count on the entire cgroup
220 * set for a task.
221 */
222 struct css_set {
223 /*
224 * Set of subsystem states, one for each subsystem. This array is
225 * immutable after creation apart from the init_css_set during
226 * subsystem registration (at boot time).
227 */
228 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
229
230 /* reference count */
231 refcount_t refcount;
232
233 /*
234 * For a domain cgroup, the following points to self. If threaded,
235 * to the matching cset of the nearest domain ancestor. The
236 * dom_cset provides access to the domain cgroup and its csses to
237 * which domain level resource consumptions should be charged.
238 */
239 struct css_set *dom_cset;
240
241 /* the default cgroup associated with this css_set */
242 struct cgroup *dfl_cgrp;
243
244 /* internal task count, protected by css_set_lock */
245 int nr_tasks;
246
247 /*
248 * Lists running through all tasks using this cgroup group.
249 * mg_tasks lists tasks which belong to this cset but are in the
250 * process of being migrated out or in. Protected by
251 * css_set_lock, but, during migration, once tasks are moved to
252 * mg_tasks, it can be read safely while holding cgroup_mutex.
253 */
254 struct list_head tasks;
255 struct list_head mg_tasks;
256 struct list_head dying_tasks;
257
258 /* all css_task_iters currently walking this cset */
259 struct list_head task_iters;
260
261 /*
262 * On the default hierarchy, ->subsys[ssid] may point to a css
263 * attached to an ancestor instead of the cgroup this css_set is
264 * associated with. The following node is anchored at
265 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
266 * iterate through all css's attached to a given cgroup.
267 */
268 struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
269
270 /* all threaded csets whose ->dom_cset points to this cset */
271 struct list_head threaded_csets;
272 struct list_head threaded_csets_node;
273
274 /*
275 * List running through all cgroup groups in the same hash
276 * slot. Protected by css_set_lock
277 */
278 struct hlist_node hlist;
279
280 /*
281 * List of cgrp_cset_links pointing at cgroups referenced from this
282 * css_set. Protected by css_set_lock.
283 */
284 struct list_head cgrp_links;
285
286 /*
287 * List of csets participating in the on-going migration either as
288 * source or destination. Protected by cgroup_mutex.
289 */
290 struct list_head mg_src_preload_node;
291 struct list_head mg_dst_preload_node;
292 struct list_head mg_node;
293
294 /*
295 * If this cset is acting as the source of migration the following
296 * two fields are set. mg_src_cgrp and mg_dst_cgrp are
297 * respectively the source and destination cgroups of the on-going
298 * migration. mg_dst_cset is the destination cset the target tasks
299 * on this cset should be migrated to. Protected by cgroup_mutex.
300 */
301 struct cgroup *mg_src_cgrp;
302 struct cgroup *mg_dst_cgrp;
303 struct css_set *mg_dst_cset;
304
305 /* dead and being drained, ignore for migration */
306 bool dead;
307
308 /* For RCU-protected deletion */
309 struct rcu_head rcu_head;
310 };
311
312 struct cgroup_base_stat {
313 struct task_cputime cputime;
314
315 #ifdef CONFIG_SCHED_CORE
316 u64 forceidle_sum;
317 #endif
318 };
319
320 /*
321 * rstat - cgroup scalable recursive statistics. Accounting is done
322 * per-cpu in cgroup_rstat_cpu which is then lazily propagated up the
323 * hierarchy on reads.
324 *
325 * When a stat gets updated, the cgroup_rstat_cpu and its ancestors are
326 * linked into the updated tree. On the following read, propagation only
327 * considers and consumes the updated tree. This makes reading O(the
328 * number of descendants which have been active since last read) instead of
329 * O(the total number of descendants).
330 *
331 * This is important because there can be a lot of (draining) cgroups which
332 * aren't active and stat may be read frequently. The combination can
333 * become very expensive. By propagating selectively, increasing reading
334 * frequency decreases the cost of each read.
335 *
336 * This struct hosts both the fields which implement the above -
337 * updated_children and updated_next - and the fields which track basic
338 * resource statistics on top of it - bsync, bstat and last_bstat.
339 */
340 struct cgroup_rstat_cpu {
341 /*
342 * ->bsync protects ->bstat. These are the only fields which get
343 * updated in the hot path.
344 */
345 struct u64_stats_sync bsync;
346 struct cgroup_base_stat bstat;
347
348 /*
349 * Snapshots at the last reading. These are used to calculate the
350 * deltas to propagate to the global counters.
351 */
352 struct cgroup_base_stat last_bstat;
353
354 /*
355 * This field is used to record the cumulative per-cpu time of
356 * the cgroup and its descendants. Currently it can be read via
357 * eBPF/drgn etc, and we are still trying to determine how to
358 * expose it in the cgroupfs interface.
359 */
360 struct cgroup_base_stat subtree_bstat;
361
362 /*
363 * Snapshots at the last reading. These are used to calculate the
364 * deltas to propagate to the per-cpu subtree_bstat.
365 */
366 struct cgroup_base_stat last_subtree_bstat;
367
368 /*
369 * Child cgroups with stat updates on this cpu since the last read
370 * are linked on the parent's ->updated_children through
371 * ->updated_next.
372 *
373 * In addition to being more compact, singly-linked list pointing
374 * to the cgroup makes it unnecessary for each per-cpu struct to
375 * point back to the associated cgroup.
376 *
377 * Protected by per-cpu cgroup_rstat_cpu_lock.
378 */
379 struct cgroup *updated_children; /* terminated by self cgroup */
380 struct cgroup *updated_next; /* NULL iff not on the list */
381 };
382
383 struct cgroup_freezer_state {
384 /* Should the cgroup and its descendants be frozen. */
385 bool freeze;
386
387 /* Should the cgroup actually be frozen? */
388 int e_freeze;
389
390 /* Fields below are protected by css_set_lock */
391
392 /* Number of frozen descendant cgroups */
393 int nr_frozen_descendants;
394
395 /*
396 * Number of tasks, which are counted as frozen:
397 * frozen, SIGSTOPped, and PTRACEd.
398 */
399 int nr_frozen_tasks;
400 };
401
402 struct cgroup {
403 /* self css with NULL ->ss, points back to this cgroup */
404 struct cgroup_subsys_state self;
405
406 unsigned long flags; /* "unsigned long" so bitops work */
407
408 /*
409 * The depth this cgroup is at. The root is at depth zero and each
410 * step down the hierarchy increments the level. This along with
411 * ancestors[] can determine whether a given cgroup is a
412 * descendant of another without traversing the hierarchy.
413 */
414 int level;
415
416 /* Maximum allowed descent tree depth */
417 int max_depth;
418
419 /*
420 * Keep track of total numbers of visible and dying descent cgroups.
421 * Dying cgroups are cgroups which were deleted by a user,
422 * but are still existing because someone else is holding a reference.
423 * max_descendants is a maximum allowed number of descent cgroups.
424 *
425 * nr_descendants and nr_dying_descendants are protected
426 * by cgroup_mutex and css_set_lock. It's fine to read them holding
427 * any of cgroup_mutex and css_set_lock; for writing both locks
428 * should be held.
429 */
430 int nr_descendants;
431 int nr_dying_descendants;
432 int max_descendants;
433
434 /*
435 * Each non-empty css_set associated with this cgroup contributes
436 * one to nr_populated_csets. The counter is zero iff this cgroup
437 * doesn't have any tasks.
438 *
439 * All children which have non-zero nr_populated_csets and/or
440 * nr_populated_children of their own contribute one to either
441 * nr_populated_domain_children or nr_populated_threaded_children
442 * depending on their type. Each counter is zero iff all cgroups
443 * of the type in the subtree proper don't have any tasks.
444 */
445 int nr_populated_csets;
446 int nr_populated_domain_children;
447 int nr_populated_threaded_children;
448
449 int nr_threaded_children; /* # of live threaded child cgroups */
450
451 struct kernfs_node *kn; /* cgroup kernfs entry */
452 struct cgroup_file procs_file; /* handle for "cgroup.procs" */
453 struct cgroup_file events_file; /* handle for "cgroup.events" */
454
455 /* handles for "{cpu,memory,io,irq}.pressure" */
456 struct cgroup_file psi_files[NR_PSI_RESOURCES];
457
458 /*
459 * The bitmask of subsystems enabled on the child cgroups.
460 * ->subtree_control is the one configured through
461 * "cgroup.subtree_control" while ->subtree_ss_mask is the effective
462 * one which may have more subsystems enabled. Controller knobs
463 * are made available iff it's enabled in ->subtree_control.
464 */
465 u16 subtree_control;
466 u16 subtree_ss_mask;
467 u16 old_subtree_control;
468 u16 old_subtree_ss_mask;
469
470 /* Private pointers for each registered subsystem */
471 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
472
473 struct cgroup_root *root;
474
475 /*
476 * List of cgrp_cset_links pointing at css_sets with tasks in this
477 * cgroup. Protected by css_set_lock.
478 */
479 struct list_head cset_links;
480
481 /*
482 * On the default hierarchy, a css_set for a cgroup with some
483 * susbsys disabled will point to css's which are associated with
484 * the closest ancestor which has the subsys enabled. The
485 * following lists all css_sets which point to this cgroup's css
486 * for the given subsystem.
487 */
488 struct list_head e_csets[CGROUP_SUBSYS_COUNT];
489
490 /*
491 * If !threaded, self. If threaded, it points to the nearest
492 * domain ancestor. Inside a threaded subtree, cgroups are exempt
493 * from process granularity and no-internal-task constraint.
494 * Domain level resource consumptions which aren't tied to a
495 * specific task are charged to the dom_cgrp.
496 */
497 struct cgroup *dom_cgrp;
498 struct cgroup *old_dom_cgrp; /* used while enabling threaded */
499
500 /* per-cpu recursive resource statistics */
501 struct cgroup_rstat_cpu __percpu *rstat_cpu;
502 struct list_head rstat_css_list;
503
504 /*
505 * Add padding to separate the read mostly rstat_cpu and
506 * rstat_css_list into a different cacheline from the following
507 * rstat_flush_next and *bstat fields which can have frequent updates.
508 */
509 CACHELINE_PADDING(_pad_);
510
511 /*
512 * A singly-linked list of cgroup structures to be rstat flushed.
513 * This is a scratch field to be used exclusively by
514 * cgroup_rstat_flush_locked() and protected by cgroup_rstat_lock.
515 */
516 struct cgroup *rstat_flush_next;
517
518 /* cgroup basic resource statistics */
519 struct cgroup_base_stat last_bstat;
520 struct cgroup_base_stat bstat;
521 struct prev_cputime prev_cputime; /* for printing out cputime */
522
523 /*
524 * list of pidlists, up to two for each namespace (one for procs, one
525 * for tasks); created on demand.
526 */
527 struct list_head pidlists;
528 struct mutex pidlist_mutex;
529
530 /* used to wait for offlining of csses */
531 wait_queue_head_t offline_waitq;
532
533 /* used to schedule release agent */
534 struct work_struct release_agent_work;
535
536 /* used to track pressure stalls */
537 struct psi_group *psi;
538
539 /* used to store eBPF programs */
540 struct cgroup_bpf bpf;
541
542 /* Used to store internal freezer state */
543 struct cgroup_freezer_state freezer;
544
545 #ifdef CONFIG_BPF_SYSCALL
546 struct bpf_local_storage __rcu *bpf_cgrp_storage;
547 #endif
548
549 /* All ancestors including self */
550 struct cgroup *ancestors[];
551 };
552
553 /*
554 * A cgroup_root represents the root of a cgroup hierarchy, and may be
555 * associated with a kernfs_root to form an active hierarchy. This is
556 * internal to cgroup core. Don't access directly from controllers.
557 */
558 struct cgroup_root {
559 struct kernfs_root *kf_root;
560
561 /* The bitmask of subsystems attached to this hierarchy */
562 unsigned int subsys_mask;
563
564 /* Unique id for this hierarchy. */
565 int hierarchy_id;
566
567 /* A list running through the active hierarchies */
568 struct list_head root_list;
569 struct rcu_head rcu; /* Must be near the top */
570
571 /*
572 * The root cgroup. The containing cgroup_root will be destroyed on its
573 * release. cgrp->ancestors[0] will be used overflowing into the
574 * following field. cgrp_ancestor_storage must immediately follow.
575 */
576 struct cgroup cgrp;
577
578 /* must follow cgrp for cgrp->ancestors[0], see above */
579 struct cgroup *cgrp_ancestor_storage;
580
581 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
582 atomic_t nr_cgrps;
583
584 /* Hierarchy-specific flags */
585 unsigned int flags;
586
587 /* The path to use for release notifications. */
588 char release_agent_path[PATH_MAX];
589
590 /* The name for this hierarchy - may be empty */
591 char name[MAX_CGROUP_ROOT_NAMELEN];
592 };
593
594 /*
595 * struct cftype: handler definitions for cgroup control files
596 *
597 * When reading/writing to a file:
598 * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
599 * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
600 */
601 struct cftype {
602 /*
603 * By convention, the name should begin with the name of the
604 * subsystem, followed by a period. Zero length string indicates
605 * end of cftype array.
606 */
607 char name[MAX_CFTYPE_NAME];
608 unsigned long private;
609
610 /*
611 * The maximum length of string, excluding trailing nul, that can
612 * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
613 */
614 size_t max_write_len;
615
616 /* CFTYPE_* flags */
617 unsigned int flags;
618
619 /*
620 * If non-zero, should contain the offset from the start of css to
621 * a struct cgroup_file field. cgroup will record the handle of
622 * the created file into it. The recorded handle can be used as
623 * long as the containing css remains accessible.
624 */
625 unsigned int file_offset;
626
627 /*
628 * Fields used for internal bookkeeping. Initialized automatically
629 * during registration.
630 */
631 struct cgroup_subsys *ss; /* NULL for cgroup core files */
632 struct list_head node; /* anchored at ss->cfts */
633 struct kernfs_ops *kf_ops;
634
635 int (*open)(struct kernfs_open_file *of);
636 void (*release)(struct kernfs_open_file *of);
637
638 /*
639 * read_u64() is a shortcut for the common case of returning a
640 * single integer. Use it in place of read()
641 */
642 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
643 /*
644 * read_s64() is a signed version of read_u64()
645 */
646 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
647
648 /* generic seq_file read interface */
649 int (*seq_show)(struct seq_file *sf, void *v);
650
651 /* optional ops, implement all or none */
652 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
653 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
654 void (*seq_stop)(struct seq_file *sf, void *v);
655
656 /*
657 * write_u64() is a shortcut for the common case of accepting
658 * a single integer (as parsed by simple_strtoull) from
659 * userspace. Use in place of write(); return 0 or error.
660 */
661 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
662 u64 val);
663 /*
664 * write_s64() is a signed version of write_u64()
665 */
666 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
667 s64 val);
668
669 /*
670 * write() is the generic write callback which maps directly to
671 * kernfs write operation and overrides all other operations.
672 * Maximum write size is determined by ->max_write_len. Use
673 * of_css/cft() to access the associated css and cft.
674 */
675 ssize_t (*write)(struct kernfs_open_file *of,
676 char *buf, size_t nbytes, loff_t off);
677
678 __poll_t (*poll)(struct kernfs_open_file *of,
679 struct poll_table_struct *pt);
680
681 struct lock_class_key lockdep_key;
682 };
683
684 /*
685 * Control Group subsystem type.
686 * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
687 */
688 struct cgroup_subsys {
689 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
690 int (*css_online)(struct cgroup_subsys_state *css);
691 void (*css_offline)(struct cgroup_subsys_state *css);
692 void (*css_released)(struct cgroup_subsys_state *css);
693 void (*css_free)(struct cgroup_subsys_state *css);
694 void (*css_reset)(struct cgroup_subsys_state *css);
695 void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu);
696 int (*css_extra_stat_show)(struct seq_file *seq,
697 struct cgroup_subsys_state *css);
698 int (*css_local_stat_show)(struct seq_file *seq,
699 struct cgroup_subsys_state *css);
700
701 int (*can_attach)(struct cgroup_taskset *tset);
702 void (*cancel_attach)(struct cgroup_taskset *tset);
703 void (*attach)(struct cgroup_taskset *tset);
704 void (*post_attach)(void);
705 int (*can_fork)(struct task_struct *task,
706 struct css_set *cset);
707 void (*cancel_fork)(struct task_struct *task, struct css_set *cset);
708 void (*fork)(struct task_struct *task);
709 void (*exit)(struct task_struct *task);
710 void (*release)(struct task_struct *task);
711 void (*bind)(struct cgroup_subsys_state *root_css);
712
713 bool early_init:1;
714
715 /*
716 * If %true, the controller, on the default hierarchy, doesn't show
717 * up in "cgroup.controllers" or "cgroup.subtree_control", is
718 * implicitly enabled on all cgroups on the default hierarchy, and
719 * bypasses the "no internal process" constraint. This is for
720 * utility type controllers which is transparent to userland.
721 *
722 * An implicit controller can be stolen from the default hierarchy
723 * anytime and thus must be okay with offline csses from previous
724 * hierarchies coexisting with csses for the current one.
725 */
726 bool implicit_on_dfl:1;
727
728 /*
729 * If %true, the controller, supports threaded mode on the default
730 * hierarchy. In a threaded subtree, both process granularity and
731 * no-internal-process constraint are ignored and a threaded
732 * controllers should be able to handle that.
733 *
734 * Note that as an implicit controller is automatically enabled on
735 * all cgroups on the default hierarchy, it should also be
736 * threaded. implicit && !threaded is not supported.
737 */
738 bool threaded:1;
739
740 /* the following two fields are initialized automatically during boot */
741 int id;
742 const char *name;
743
744 /* optional, initialized automatically during boot if not set */
745 const char *legacy_name;
746
747 /* link to parent, protected by cgroup_lock() */
748 struct cgroup_root *root;
749
750 /* idr for css->id */
751 struct idr css_idr;
752
753 /*
754 * List of cftypes. Each entry is the first entry of an array
755 * terminated by zero length name.
756 */
757 struct list_head cfts;
758
759 /*
760 * Base cftypes which are automatically registered. The two can
761 * point to the same array.
762 */
763 struct cftype *dfl_cftypes; /* for the default hierarchy */
764 struct cftype *legacy_cftypes; /* for the legacy hierarchies */
765
766 /*
767 * A subsystem may depend on other subsystems. When such subsystem
768 * is enabled on a cgroup, the depended-upon subsystems are enabled
769 * together if available. Subsystems enabled due to dependency are
770 * not visible to userland until explicitly enabled. The following
771 * specifies the mask of subsystems that this one depends on.
772 */
773 unsigned int depends_on;
774 };
775
776 extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
777
778 /**
779 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
780 * @tsk: target task
781 *
782 * Allows cgroup operations to synchronize against threadgroup changes
783 * using a percpu_rw_semaphore.
784 */
785 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
786 {
787 percpu_down_read(&cgroup_threadgroup_rwsem);
788 }
789
790 /**
791 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
792 * @tsk: target task
793 *
794 * Counterpart of cgroup_threadcgroup_change_begin().
795 */
796 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
797 {
798 percpu_up_read(&cgroup_threadgroup_rwsem);
799 }
800
801 #else /* CONFIG_CGROUPS */
802
803 #define CGROUP_SUBSYS_COUNT 0
804
805 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
806 {
807 might_sleep();
808 }
809
810 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
811
812 #endif /* CONFIG_CGROUPS */
813
814 #ifdef CONFIG_SOCK_CGROUP_DATA
815
816 /*
817 * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
818 * per-socket cgroup information except for memcg association.
819 *
820 * On legacy hierarchies, net_prio and net_cls controllers directly
821 * set attributes on each sock which can then be tested by the network
822 * layer. On the default hierarchy, each sock is associated with the
823 * cgroup it was created in and the networking layer can match the
824 * cgroup directly.
825 */
826 struct sock_cgroup_data {
827 struct cgroup *cgroup; /* v2 */
828 #ifdef CONFIG_CGROUP_NET_CLASSID
829 u32 classid; /* v1 */
830 #endif
831 #ifdef CONFIG_CGROUP_NET_PRIO
832 u16 prioidx; /* v1 */
833 #endif
834 };
835
836 static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
837 {
838 #ifdef CONFIG_CGROUP_NET_PRIO
839 return READ_ONCE(skcd->prioidx);
840 #else
841 return 1;
842 #endif
843 }
844
845 static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
846 {
847 #ifdef CONFIG_CGROUP_NET_CLASSID
848 return READ_ONCE(skcd->classid);
849 #else
850 return 0;
851 #endif
852 }
853
854 static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
855 u16 prioidx)
856 {
857 #ifdef CONFIG_CGROUP_NET_PRIO
858 WRITE_ONCE(skcd->prioidx, prioidx);
859 #endif
860 }
861
862 static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
863 u32 classid)
864 {
865 #ifdef CONFIG_CGROUP_NET_CLASSID
866 WRITE_ONCE(skcd->classid, classid);
867 #endif
868 }
869
870 #else /* CONFIG_SOCK_CGROUP_DATA */
871
872 struct sock_cgroup_data {
873 };
874
875 #endif /* CONFIG_SOCK_CGROUP_DATA */
876
877 #endif /* _LINUX_CGROUP_DEFS_H */
878
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