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
27struct cgroup;
28struct cgroup_root;
29struct cgroup_subsys;
30struct cgroup_taskset;
31struct kernfs_node;
32struct kernfs_ops;
33struct kernfs_open_file;
34struct seq_file;
35struct 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,
43enum 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 */
50enum {
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 */
59enum {
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 */
80enum {
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/* cftype->flags */
126enum {
127 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
128 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
129 CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */
130
131 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
132 CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
133 CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */
134
135 /* internal flags, do not use outside cgroup core proper */
136 __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
137 __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
138 __CFTYPE_ADDED = (1 << 18),
139};
140
141/*
142 * cgroup_file is the handle for a file instance created in a cgroup which
143 * is used, for example, to generate file changed notifications. This can
144 * be obtained by setting cftype->file_offset.
145 */
146struct cgroup_file {
147 /* do not access any fields from outside cgroup core */
148 struct kernfs_node *kn;
149 unsigned long notified_at;
150 struct timer_list notify_timer;
151};
152
153/*
154 * Per-subsystem/per-cgroup state maintained by the system. This is the
155 * fundamental structural building block that controllers deal with.
156 *
157 * Fields marked with "PI:" are public and immutable and may be accessed
158 * directly without synchronization.
159 */
160struct cgroup_subsys_state {
161 /* PI: the cgroup that this css is attached to */
162 struct cgroup *cgroup;
163
164 /* PI: the cgroup subsystem that this css is attached to */
165 struct cgroup_subsys *ss;
166
167 /* reference count - access via css_[try]get() and css_put() */
168 struct percpu_ref refcnt;
169
170 /* siblings list anchored at the parent's ->children */
171 struct list_head sibling;
172 struct list_head children;
173
174 /* flush target list anchored at cgrp->rstat_css_list */
175 struct list_head rstat_css_node;
176
177 /*
178 * PI: Subsys-unique ID. 0 is unused and root is always 1. The
179 * matching css can be looked up using css_from_id().
180 */
181 int id;
182
183 unsigned int flags;
184
185 /*
186 * Monotonically increasing unique serial number which defines a
187 * uniform order among all csses. It's guaranteed that all
188 * ->children lists are in the ascending order of ->serial_nr and
189 * used to allow interrupting and resuming iterations.
190 */
191 u64 serial_nr;
192
193 /*
194 * Incremented by online self and children. Used to guarantee that
195 * parents are not offlined before their children.
196 */
197 atomic_t online_cnt;
198
199 /* percpu_ref killing and RCU release */
200 struct work_struct destroy_work;
201 struct rcu_work destroy_rwork;
202
203 /*
204 * PI: the parent css. Placed here for cache proximity to following
205 * fields of the containing structure.
206 */
207 struct cgroup_subsys_state *parent;
208};
209
210/*
211 * A css_set is a structure holding pointers to a set of
212 * cgroup_subsys_state objects. This saves space in the task struct
213 * object and speeds up fork()/exit(), since a single inc/dec and a
214 * list_add()/del() can bump the reference count on the entire cgroup
215 * set for a task.
216 */
217struct css_set {
218 /*
219 * Set of subsystem states, one for each subsystem. This array is
220 * immutable after creation apart from the init_css_set during
221 * subsystem registration (at boot time).
222 */
223 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
224
225 /* reference count */
226 refcount_t refcount;
227
228 /*
229 * For a domain cgroup, the following points to self. If threaded,
230 * to the matching cset of the nearest domain ancestor. The
231 * dom_cset provides access to the domain cgroup and its csses to
232 * which domain level resource consumptions should be charged.
233 */
234 struct css_set *dom_cset;
235
236 /* the default cgroup associated with this css_set */
237 struct cgroup *dfl_cgrp;
238
239 /* internal task count, protected by css_set_lock */
240 int nr_tasks;
241
242 /*
243 * Lists running through all tasks using this cgroup group.
244 * mg_tasks lists tasks which belong to this cset but are in the
245 * process of being migrated out or in. Protected by
246 * css_set_lock, but, during migration, once tasks are moved to
247 * mg_tasks, it can be read safely while holding cgroup_mutex.
248 */
249 struct list_head tasks;
250 struct list_head mg_tasks;
251 struct list_head dying_tasks;
252
253 /* all css_task_iters currently walking this cset */
254 struct list_head task_iters;
255
256 /*
257 * On the default hierarchy, ->subsys[ssid] may point to a css
258 * attached to an ancestor instead of the cgroup this css_set is
259 * associated with. The following node is anchored at
260 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
261 * iterate through all css's attached to a given cgroup.
262 */
263 struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
264
265 /* all threaded csets whose ->dom_cset points to this cset */
266 struct list_head threaded_csets;
267 struct list_head threaded_csets_node;
268
269 /*
270 * List running through all cgroup groups in the same hash
271 * slot. Protected by css_set_lock
272 */
273 struct hlist_node hlist;
274
275 /*
276 * List of cgrp_cset_links pointing at cgroups referenced from this
277 * css_set. Protected by css_set_lock.
278 */
279 struct list_head cgrp_links;
280
281 /*
282 * List of csets participating in the on-going migration either as
283 * source or destination. Protected by cgroup_mutex.
284 */
285 struct list_head mg_src_preload_node;
286 struct list_head mg_dst_preload_node;
287 struct list_head mg_node;
288
289 /*
290 * If this cset is acting as the source of migration the following
291 * two fields are set. mg_src_cgrp and mg_dst_cgrp are
292 * respectively the source and destination cgroups of the on-going
293 * migration. mg_dst_cset is the destination cset the target tasks
294 * on this cset should be migrated to. Protected by cgroup_mutex.
295 */
296 struct cgroup *mg_src_cgrp;
297 struct cgroup *mg_dst_cgrp;
298 struct css_set *mg_dst_cset;
299
300 /* dead and being drained, ignore for migration */
301 bool dead;
302
303 /* For RCU-protected deletion */
304 struct rcu_head rcu_head;
305};
306
307struct cgroup_base_stat {
308 struct task_cputime cputime;
309
310#ifdef CONFIG_SCHED_CORE
311 u64 forceidle_sum;
312#endif
313};
314
315/*
316 * rstat - cgroup scalable recursive statistics. Accounting is done
317 * per-cpu in cgroup_rstat_cpu which is then lazily propagated up the
318 * hierarchy on reads.
319 *
320 * When a stat gets updated, the cgroup_rstat_cpu and its ancestors are
321 * linked into the updated tree. On the following read, propagation only
322 * considers and consumes the updated tree. This makes reading O(the
323 * number of descendants which have been active since last read) instead of
324 * O(the total number of descendants).
325 *
326 * This is important because there can be a lot of (draining) cgroups which
327 * aren't active and stat may be read frequently. The combination can
328 * become very expensive. By propagating selectively, increasing reading
329 * frequency decreases the cost of each read.
330 *
331 * This struct hosts both the fields which implement the above -
332 * updated_children and updated_next - and the fields which track basic
333 * resource statistics on top of it - bsync, bstat and last_bstat.
334 */
335struct cgroup_rstat_cpu {
336 /*
337 * ->bsync protects ->bstat. These are the only fields which get
338 * updated in the hot path.
339 */
340 struct u64_stats_sync bsync;
341 struct cgroup_base_stat bstat;
342
343 /*
344 * Snapshots at the last reading. These are used to calculate the
345 * deltas to propagate to the global counters.
346 */
347 struct cgroup_base_stat last_bstat;
348
349 /*
350 * This field is used to record the cumulative per-cpu time of
351 * the cgroup and its descendants. Currently it can be read via
352 * eBPF/drgn etc, and we are still trying to determine how to
353 * expose it in the cgroupfs interface.
354 */
355 struct cgroup_base_stat subtree_bstat;
356
357 /*
358 * Snapshots at the last reading. These are used to calculate the
359 * deltas to propagate to the per-cpu subtree_bstat.
360 */
361 struct cgroup_base_stat last_subtree_bstat;
362
363 /*
364 * Child cgroups with stat updates on this cpu since the last read
365 * are linked on the parent's ->updated_children through
366 * ->updated_next.
367 *
368 * In addition to being more compact, singly-linked list pointing
369 * to the cgroup makes it unnecessary for each per-cpu struct to
370 * point back to the associated cgroup.
371 *
372 * Protected by per-cpu cgroup_rstat_cpu_lock.
373 */
374 struct cgroup *updated_children; /* terminated by self cgroup */
375 struct cgroup *updated_next; /* NULL iff not on the list */
376};
377
378struct cgroup_freezer_state {
379 /* Should the cgroup and its descendants be frozen. */
380 bool freeze;
381
382 /* Should the cgroup actually be frozen? */
383 int e_freeze;
384
385 /* Fields below are protected by css_set_lock */
386
387 /* Number of frozen descendant cgroups */
388 int nr_frozen_descendants;
389
390 /*
391 * Number of tasks, which are counted as frozen:
392 * frozen, SIGSTOPped, and PTRACEd.
393 */
394 int nr_frozen_tasks;
395};
396
397struct cgroup {
398 /* self css with NULL ->ss, points back to this cgroup */
399 struct cgroup_subsys_state self;
400
401 unsigned long flags; /* "unsigned long" so bitops work */
402
403 /*
404 * The depth this cgroup is at. The root is at depth zero and each
405 * step down the hierarchy increments the level. This along with
406 * ancestors[] can determine whether a given cgroup is a
407 * descendant of another without traversing the hierarchy.
408 */
409 int level;
410
411 /* Maximum allowed descent tree depth */
412 int max_depth;
413
414 /*
415 * Keep track of total numbers of visible and dying descent cgroups.
416 * Dying cgroups are cgroups which were deleted by a user,
417 * but are still existing because someone else is holding a reference.
418 * max_descendants is a maximum allowed number of descent cgroups.
419 *
420 * nr_descendants and nr_dying_descendants are protected
421 * by cgroup_mutex and css_set_lock. It's fine to read them holding
422 * any of cgroup_mutex and css_set_lock; for writing both locks
423 * should be held.
424 */
425 int nr_descendants;
426 int nr_dying_descendants;
427 int max_descendants;
428
429 /*
430 * Each non-empty css_set associated with this cgroup contributes
431 * one to nr_populated_csets. The counter is zero iff this cgroup
432 * doesn't have any tasks.
433 *
434 * All children which have non-zero nr_populated_csets and/or
435 * nr_populated_children of their own contribute one to either
436 * nr_populated_domain_children or nr_populated_threaded_children
437 * depending on their type. Each counter is zero iff all cgroups
438 * of the type in the subtree proper don't have any tasks.
439 */
440 int nr_populated_csets;
441 int nr_populated_domain_children;
442 int nr_populated_threaded_children;
443
444 int nr_threaded_children; /* # of live threaded child cgroups */
445
446 struct kernfs_node *kn; /* cgroup kernfs entry */
447 struct cgroup_file procs_file; /* handle for "cgroup.procs" */
448 struct cgroup_file events_file; /* handle for "cgroup.events" */
449
450 /* handles for "{cpu,memory,io,irq}.pressure" */
451 struct cgroup_file psi_files[NR_PSI_RESOURCES];
452
453 /*
454 * The bitmask of subsystems enabled on the child cgroups.
455 * ->subtree_control is the one configured through
456 * "cgroup.subtree_control" while ->subtree_ss_mask is the effective
457 * one which may have more subsystems enabled. Controller knobs
458 * are made available iff it's enabled in ->subtree_control.
459 */
460 u16 subtree_control;
461 u16 subtree_ss_mask;
462 u16 old_subtree_control;
463 u16 old_subtree_ss_mask;
464
465 /* Private pointers for each registered subsystem */
466 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
467
468 struct cgroup_root *root;
469
470 /*
471 * List of cgrp_cset_links pointing at css_sets with tasks in this
472 * cgroup. Protected by css_set_lock.
473 */
474 struct list_head cset_links;
475
476 /*
477 * On the default hierarchy, a css_set for a cgroup with some
478 * susbsys disabled will point to css's which are associated with
479 * the closest ancestor which has the subsys enabled. The
480 * following lists all css_sets which point to this cgroup's css
481 * for the given subsystem.
482 */
483 struct list_head e_csets[CGROUP_SUBSYS_COUNT];
484
485 /*
486 * If !threaded, self. If threaded, it points to the nearest
487 * domain ancestor. Inside a threaded subtree, cgroups are exempt
488 * from process granularity and no-internal-task constraint.
489 * Domain level resource consumptions which aren't tied to a
490 * specific task are charged to the dom_cgrp.
491 */
492 struct cgroup *dom_cgrp;
493 struct cgroup *old_dom_cgrp; /* used while enabling threaded */
494
495 /* per-cpu recursive resource statistics */
496 struct cgroup_rstat_cpu __percpu *rstat_cpu;
497 struct list_head rstat_css_list;
498
499 /*
500 * Add padding to separate the read mostly rstat_cpu and
501 * rstat_css_list into a different cacheline from the following
502 * rstat_flush_next and *bstat fields which can have frequent updates.
503 */
504 CACHELINE_PADDING(_pad_);
505
506 /*
507 * A singly-linked list of cgroup structures to be rstat flushed.
508 * This is a scratch field to be used exclusively by
509 * cgroup_rstat_flush_locked() and protected by cgroup_rstat_lock.
510 */
511 struct cgroup *rstat_flush_next;
512
513 /* cgroup basic resource statistics */
514 struct cgroup_base_stat last_bstat;
515 struct cgroup_base_stat bstat;
516 struct prev_cputime prev_cputime; /* for printing out cputime */
517
518 /*
519 * list of pidlists, up to two for each namespace (one for procs, one
520 * for tasks); created on demand.
521 */
522 struct list_head pidlists;
523 struct mutex pidlist_mutex;
524
525 /* used to wait for offlining of csses */
526 wait_queue_head_t offline_waitq;
527
528 /* used to schedule release agent */
529 struct work_struct release_agent_work;
530
531 /* used to track pressure stalls */
532 struct psi_group *psi;
533
534 /* used to store eBPF programs */
535 struct cgroup_bpf bpf;
536
537 /* If there is block congestion on this cgroup. */
538 atomic_t congestion_count;
539
540 /* Used to store internal freezer state */
541 struct cgroup_freezer_state freezer;
542
543#ifdef CONFIG_BPF_SYSCALL
544 struct bpf_local_storage __rcu *bpf_cgrp_storage;
545#endif
546
547 /* All ancestors including self */
548 struct cgroup *ancestors[];
549};
550
551/*
552 * A cgroup_root represents the root of a cgroup hierarchy, and may be
553 * associated with a kernfs_root to form an active hierarchy. This is
554 * internal to cgroup core. Don't access directly from controllers.
555 */
556struct cgroup_root {
557 struct kernfs_root *kf_root;
558
559 /* The bitmask of subsystems attached to this hierarchy */
560 unsigned int subsys_mask;
561
562 /* Unique id for this hierarchy. */
563 int hierarchy_id;
564
565 /* A list running through the active hierarchies */
566 struct list_head root_list;
567 struct rcu_head rcu; /* Must be near the top */
568
569 /*
570 * The root cgroup. The containing cgroup_root will be destroyed on its
571 * release. cgrp->ancestors[0] will be used overflowing into the
572 * following field. cgrp_ancestor_storage must immediately follow.
573 */
574 struct cgroup cgrp;
575
576 /* must follow cgrp for cgrp->ancestors[0], see above */
577 struct cgroup *cgrp_ancestor_storage;
578
579 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
580 atomic_t nr_cgrps;
581
582 /* Hierarchy-specific flags */
583 unsigned int flags;
584
585 /* The path to use for release notifications. */
586 char release_agent_path[PATH_MAX];
587
588 /* The name for this hierarchy - may be empty */
589 char name[MAX_CGROUP_ROOT_NAMELEN];
590};
591
592/*
593 * struct cftype: handler definitions for cgroup control files
594 *
595 * When reading/writing to a file:
596 * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
597 * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
598 */
599struct cftype {
600 /*
601 * By convention, the name should begin with the name of the
602 * subsystem, followed by a period. Zero length string indicates
603 * end of cftype array.
604 */
605 char name[MAX_CFTYPE_NAME];
606 unsigned long private;
607
608 /*
609 * The maximum length of string, excluding trailing nul, that can
610 * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
611 */
612 size_t max_write_len;
613
614 /* CFTYPE_* flags */
615 unsigned int flags;
616
617 /*
618 * If non-zero, should contain the offset from the start of css to
619 * a struct cgroup_file field. cgroup will record the handle of
620 * the created file into it. The recorded handle can be used as
621 * long as the containing css remains accessible.
622 */
623 unsigned int file_offset;
624
625 /*
626 * Fields used for internal bookkeeping. Initialized automatically
627 * during registration.
628 */
629 struct cgroup_subsys *ss; /* NULL for cgroup core files */
630 struct list_head node; /* anchored at ss->cfts */
631 struct kernfs_ops *kf_ops;
632
633 int (*open)(struct kernfs_open_file *of);
634 void (*release)(struct kernfs_open_file *of);
635
636 /*
637 * read_u64() is a shortcut for the common case of returning a
638 * single integer. Use it in place of read()
639 */
640 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
641 /*
642 * read_s64() is a signed version of read_u64()
643 */
644 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
645
646 /* generic seq_file read interface */
647 int (*seq_show)(struct seq_file *sf, void *v);
648
649 /* optional ops, implement all or none */
650 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
651 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
652 void (*seq_stop)(struct seq_file *sf, void *v);
653
654 /*
655 * write_u64() is a shortcut for the common case of accepting
656 * a single integer (as parsed by simple_strtoull) from
657 * userspace. Use in place of write(); return 0 or error.
658 */
659 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
660 u64 val);
661 /*
662 * write_s64() is a signed version of write_u64()
663 */
664 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
665 s64 val);
666
667 /*
668 * write() is the generic write callback which maps directly to
669 * kernfs write operation and overrides all other operations.
670 * Maximum write size is determined by ->max_write_len. Use
671 * of_css/cft() to access the associated css and cft.
672 */
673 ssize_t (*write)(struct kernfs_open_file *of,
674 char *buf, size_t nbytes, loff_t off);
675
676 __poll_t (*poll)(struct kernfs_open_file *of,
677 struct poll_table_struct *pt);
678
679#ifdef CONFIG_DEBUG_LOCK_ALLOC
680 struct lock_class_key lockdep_key;
681#endif
682};
683
684/*
685 * Control Group subsystem type.
686 * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
687 */
688struct 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
776extern 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 */
785static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
786{
787 percpu_down_read(sem: &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 */
796static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
797{
798 percpu_up_read(sem: &cgroup_threadgroup_rwsem);
799}
800
801#else /* CONFIG_CGROUPS */
802
803#define CGROUP_SUBSYS_COUNT 0
804
805static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
806{
807 might_sleep();
808}
809
810static 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 */
826struct 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
836static 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
845static 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
854static 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
862static 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
872struct sock_cgroup_data {
873};
874
875#endif /* CONFIG_SOCK_CGROUP_DATA */
876
877#endif /* _LINUX_CGROUP_DEFS_H */
878

source code of linux/include/linux/cgroup-defs.h