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/sched.h>
21 #include <linux/u64_stats_sync.h>
22 #include <linux/workqueue.h>
23 #include <linux/bpf-cgroup-defs.h>
24 #include <linux/psi_types.h>
25
26 #ifdef CONFIG_CGROUPS
27
28 struct cgroup;
29 struct cgroup_root;
30 struct cgroup_subsys;
31 struct cgroup_taskset;
32 struct kernfs_node;
33 struct kernfs_ops;
34 struct kernfs_open_file;
35 struct seq_file;
36 struct poll_table_struct;
37
38 #define MAX_CGROUP_TYPE_NAMELEN 32
39 #define MAX_CGROUP_ROOT_NAMELEN 64
40 #define MAX_CFTYPE_NAME 64
41
42 /* define the enumeration of all cgroup subsystems */
43 #define SUBSYS(_x) _x ## _cgrp_id,
44 enum cgroup_subsys_id {
45 #include <linux/cgroup_subsys.h>
46 CGROUP_SUBSYS_COUNT,
47 };
48 #undef SUBSYS
49
50 /* bits in struct cgroup_subsys_state flags field */
51 enum {
52 CSS_NO_REF = (1 << 0), /* no reference counting for this css */
53 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
54 CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
55 CSS_VISIBLE = (1 << 3), /* css is visible to userland */
56 CSS_DYING = (1 << 4), /* css is dying */
57 };
58
59 /* bits in struct cgroup flags field */
60 enum {
61 /* Control Group requires release notifications to userspace */
62 CGRP_NOTIFY_ON_RELEASE,
63 /*
64 * Clone the parent's configuration when creating a new child
65 * cpuset cgroup. For historical reasons, this option can be
66 * specified at mount time and thus is implemented here.
67 */
68 CGRP_CPUSET_CLONE_CHILDREN,
69
70 /* Control group has to be frozen. */
71 CGRP_FREEZE,
72
73 /* Cgroup is frozen. */
74 CGRP_FROZEN,
75 };
76
77 /* cgroup_root->flags */
78 enum {
79 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
80 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
81
82 /*
83 * Consider namespaces as delegation boundaries. If this flag is
84 * set, controller specific interface files in a namespace root
85 * aren't writeable from inside the namespace.
86 */
87 CGRP_ROOT_NS_DELEGATE = (1 << 3),
88
89 /*
90 * Reduce latencies on dynamic cgroup modifications such as task
91 * migrations and controller on/offs by disabling percpu operation on
92 * cgroup_threadgroup_rwsem. This makes hot path operations such as
93 * forks and exits into the slow path and more expensive.
94 *
95 * Alleviate the contention between fork, exec, exit operations and
96 * writing to cgroup.procs by taking a per threadgroup rwsem instead of
97 * the global cgroup_threadgroup_rwsem. Fork and other operations
98 * from threads in different thread groups no longer contend with
99 * writing to cgroup.procs.
100 *
101 * The static usage pattern of creating a cgroup, enabling controllers,
102 * and then seeding it with CLONE_INTO_CGROUP doesn't require write
103 * locking cgroup_threadgroup_rwsem and thus doesn't benefit from
104 * favordynmod.
105 */
106 CGRP_ROOT_FAVOR_DYNMODS = (1 << 4),
107
108 /*
109 * Enable cpuset controller in v1 cgroup to use v2 behavior.
110 */
111 CGRP_ROOT_CPUSET_V2_MODE = (1 << 16),
112
113 /*
114 * Enable legacy local memory.events.
115 */
116 CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 17),
117
118 /*
119 * Enable recursive subtree protection
120 */
121 CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 18),
122
123 /*
124 * Enable hugetlb accounting for the memory controller.
125 */
126 CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING = (1 << 19),
127
128 /*
129 * Enable legacy local pids.events.
130 */
131 CGRP_ROOT_PIDS_LOCAL_EVENTS = (1 << 20),
132 };
133
134 /* cftype->flags */
135 enum {
136 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
137 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
138 CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */
139
140 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
141 CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
142 CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */
143
144 /* internal flags, do not use outside cgroup core proper */
145 __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
146 __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
147 __CFTYPE_ADDED = (1 << 18),
148 };
149
150 enum cgroup_attach_lock_mode {
151 /* Default */
152 CGRP_ATTACH_LOCK_GLOBAL,
153
154 /* When pid=0 && threadgroup=false, see comments in cgroup_procs_write_start */
155 CGRP_ATTACH_LOCK_NONE,
156
157 /* When favordynmods is on, see comments above CGRP_ROOT_FAVOR_DYNMODS */
158 CGRP_ATTACH_LOCK_PER_THREADGROUP,
159 };
160
161 /*
162 * cgroup_file is the handle for a file instance created in a cgroup which
163 * is used, for example, to generate file changed notifications. This can
164 * be obtained by setting cftype->file_offset.
165 */
166 struct cgroup_file {
167 /* do not access any fields from outside cgroup core */
168 struct kernfs_node *kn;
169 unsigned long notified_at;
170 struct timer_list notify_timer;
171 spinlock_t lock;
172 };
173
174 /*
175 * Per-subsystem/per-cgroup state maintained by the system. This is the
176 * fundamental structural building block that controllers deal with.
177 *
178 * Fields marked with "PI:" are public and immutable and may be accessed
179 * directly without synchronization.
180 */
181 struct cgroup_subsys_state {
182 /* PI: the cgroup that this css is attached to */
183 struct cgroup *cgroup;
184
185 /* PI: the cgroup subsystem that this css is attached to */
186 struct cgroup_subsys *ss;
187
188 /* reference count - access via css_[try]get() and css_put() */
189 struct percpu_ref refcnt;
190
191 /*
192 * Depending on the context, this field is initialized
193 * via css_rstat_init() at different places:
194 *
195 * when css is associated with cgroup::self
196 * when css->cgroup is the root cgroup
197 * performed in cgroup_init()
198 * when css->cgroup is not the root cgroup
199 * performed in cgroup_create()
200 * when css is associated with a subsystem
201 * when css->cgroup is the root cgroup
202 * performed in cgroup_init_subsys() in the non-early path
203 * when css->cgroup is not the root cgroup
204 * performed in css_create()
205 */
206 struct css_rstat_cpu __percpu *rstat_cpu;
207
208 /*
209 * siblings list anchored at the parent's ->children
210 *
211 * linkage is protected by cgroup_mutex or RCU
212 */
213 struct list_head sibling;
214 struct list_head children;
215
216 /*
217 * PI: Subsys-unique ID. 0 is unused and root is always 1. The
218 * matching css can be looked up using css_from_id().
219 */
220 int id;
221
222 unsigned int flags;
223
224 /*
225 * Monotonically increasing unique serial number which defines a
226 * uniform order among all csses. It's guaranteed that all
227 * ->children lists are in the ascending order of ->serial_nr and
228 * used to allow interrupting and resuming iterations.
229 */
230 u64 serial_nr;
231
232 /*
233 * Incremented by online self and children. Used to guarantee that
234 * parents are not offlined before their children.
235 */
236 atomic_t online_cnt;
237
238 /* percpu_ref killing and RCU release */
239 struct work_struct destroy_work;
240 struct rcu_work destroy_rwork;
241
242 /*
243 * PI: the parent css. Placed here for cache proximity to following
244 * fields of the containing structure.
245 */
246 struct cgroup_subsys_state *parent;
247
248 /*
249 * Keep track of total numbers of visible descendant CSSes.
250 * The total number of dying CSSes is tracked in
251 * css->cgroup->nr_dying_subsys[ssid].
252 * Protected by cgroup_mutex.
253 */
254 int nr_descendants;
255
256 /*
257 * Hierarchical populated state. For cgroup->self, nr_populated_csets
258 * counts populated csets linked via cgrp_cset_link.
259 * nr_populated_children counts immediate-child csses whose own
260 * populated state is nonzero. Protected by css_set_lock.
261 */
262 int nr_populated_csets;
263 int nr_populated_children;
264
265 /* deferred kill_css_finish() queued by css_update_populated() */
266 struct work_struct kill_finish_work;
267
268 /*
269 * A singly-linked list of css structures to be rstat flushed.
270 * This is a scratch field to be used exclusively by
271 * css_rstat_flush().
272 *
273 * Protected by rstat_base_lock when css is cgroup::self.
274 * Protected by css->ss->rstat_ss_lock otherwise.
275 */
276 struct cgroup_subsys_state *rstat_flush_next;
277 };
278
279 /*
280 * A css_set is a structure holding pointers to a set of
281 * cgroup_subsys_state objects. This saves space in the task struct
282 * object and speeds up fork()/exit(), since a single inc/dec and a
283 * list_add()/del() can bump the reference count on the entire cgroup
284 * set for a task.
285 */
286 struct css_set {
287 /*
288 * Set of subsystem states, one for each subsystem. This array is
289 * immutable after creation apart from the init_css_set during
290 * subsystem registration (at boot time).
291 */
292 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
293
294 /* reference count */
295 refcount_t refcount;
296
297 /*
298 * For a domain cgroup, the following points to self. If threaded,
299 * to the matching cset of the nearest domain ancestor. The
300 * dom_cset provides access to the domain cgroup and its csses to
301 * which domain level resource consumptions should be charged.
302 */
303 struct css_set *dom_cset;
304
305 /* the default cgroup associated with this css_set */
306 struct cgroup *dfl_cgrp;
307
308 /* internal task count, protected by css_set_lock */
309 int nr_tasks;
310
311 /*
312 * Lists running through all tasks using this cgroup group.
313 * mg_tasks lists tasks which belong to this cset but are in the
314 * process of being migrated out or in. Protected by
315 * css_set_lock, but, during migration, once tasks are moved to
316 * mg_tasks, it can be read safely while holding cgroup_mutex.
317 */
318 struct list_head tasks;
319 struct list_head mg_tasks;
320 struct list_head dying_tasks;
321
322 /* all css_task_iters currently walking this cset */
323 struct list_head task_iters;
324
325 /*
326 * On the default hierarchy, ->subsys[ssid] may point to a css
327 * attached to an ancestor instead of the cgroup this css_set is
328 * associated with. The following node is anchored at
329 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
330 * iterate through all css's attached to a given cgroup.
331 */
332 struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
333
334 /* all threaded csets whose ->dom_cset points to this cset */
335 struct list_head threaded_csets;
336 struct list_head threaded_csets_node;
337
338 /*
339 * List running through all cgroup groups in the same hash
340 * slot. Protected by css_set_lock
341 */
342 struct hlist_node hlist;
343
344 /*
345 * List of cgrp_cset_links pointing at cgroups referenced from this
346 * css_set. Protected by css_set_lock.
347 */
348 struct list_head cgrp_links;
349
350 /*
351 * List of csets participating in the on-going migration either as
352 * source or destination. Protected by cgroup_mutex.
353 */
354 struct list_head mg_src_preload_node;
355 struct list_head mg_dst_preload_node;
356 struct list_head mg_node;
357
358 /*
359 * If this cset is acting as the source of migration the following
360 * two fields are set. mg_src_cgrp and mg_dst_cgrp are
361 * respectively the source and destination cgroups of the on-going
362 * migration. mg_dst_cset is the destination cset the target tasks
363 * on this cset should be migrated to. Protected by cgroup_mutex.
364 */
365 struct cgroup *mg_src_cgrp;
366 struct cgroup *mg_dst_cgrp;
367 struct css_set *mg_dst_cset;
368
369 /* dead and being drained, ignore for migration */
370 bool dead;
371
372 /* For RCU-protected deletion */
373 struct rcu_head rcu_head;
374 };
375
376 struct cgroup_base_stat {
377 struct task_cputime cputime;
378
379 #ifdef CONFIG_SCHED_CORE
380 u64 forceidle_sum;
381 #endif
382 u64 ntime;
383 };
384
385 /*
386 * rstat - cgroup scalable recursive statistics. Accounting is done
387 * per-cpu in css_rstat_cpu which is then lazily propagated up the
388 * hierarchy on reads.
389 *
390 * When a stat gets updated, the css_rstat_cpu and its ancestors are
391 * linked into the updated tree. On the following read, propagation only
392 * considers and consumes the updated tree. This makes reading O(the
393 * number of descendants which have been active since last read) instead of
394 * O(the total number of descendants).
395 *
396 * This is important because there can be a lot of (draining) cgroups which
397 * aren't active and stat may be read frequently. The combination can
398 * become very expensive. By propagating selectively, increasing reading
399 * frequency decreases the cost of each read.
400 *
401 * This struct hosts both the fields which implement the above -
402 * updated_children and updated_next.
403 */
404 struct css_rstat_cpu {
405 /*
406 * Child cgroups with stat updates on this cpu since the last read
407 * are linked on the parent's ->updated_children through
408 * ->updated_next. updated_children is terminated by its container css.
409 */
410 struct cgroup_subsys_state *updated_children;
411 struct cgroup_subsys_state *updated_next; /* NULL if not on the list */
412
413 struct llist_node lnode; /* lockless list for update */
414 struct cgroup_subsys_state *owner; /* back pointer */
415 };
416
417 /*
418 * This struct hosts the fields which track basic resource statistics on
419 * top of it - bsync, bstat and last_bstat.
420 */
421 struct cgroup_rstat_base_cpu {
422 /*
423 * ->bsync protects ->bstat. These are the only fields which get
424 * updated in the hot path.
425 */
426 struct u64_stats_sync bsync;
427 struct cgroup_base_stat bstat;
428
429 /*
430 * Snapshots at the last reading. These are used to calculate the
431 * deltas to propagate to the global counters.
432 */
433 struct cgroup_base_stat last_bstat;
434
435 /*
436 * This field is used to record the cumulative per-cpu time of
437 * the cgroup and its descendants. Currently it can be read via
438 * eBPF/drgn etc, and we are still trying to determine how to
439 * expose it in the cgroupfs interface.
440 */
441 struct cgroup_base_stat subtree_bstat;
442
443 /*
444 * Snapshots at the last reading. These are used to calculate the
445 * deltas to propagate to the per-cpu subtree_bstat.
446 */
447 struct cgroup_base_stat last_subtree_bstat;
448 };
449
450 struct cgroup_freezer_state {
451 /* Should the cgroup and its descendants be frozen. */
452 bool freeze;
453
454 /* Should the cgroup actually be frozen? */
455 bool e_freeze;
456
457 /* Fields below are protected by css_set_lock */
458
459 /* Number of frozen descendant cgroups */
460 int nr_frozen_descendants;
461
462 /*
463 * Number of tasks, which are counted as frozen:
464 * frozen, SIGSTOPped, and PTRACEd.
465 */
466 int nr_frozen_tasks;
467
468 /* Freeze time data consistency protection */
469 seqcount_spinlock_t freeze_seq;
470
471 /*
472 * Most recent time the cgroup was requested to freeze.
473 * Accesses guarded by freeze_seq counter. Writes serialized
474 * by css_set_lock.
475 */
476 u64 freeze_start_nsec;
477
478 /*
479 * Total duration the cgroup has spent freezing.
480 * Accesses guarded by freeze_seq counter. Writes serialized
481 * by css_set_lock.
482 */
483 u64 frozen_nsec;
484 };
485
486 struct cgroup {
487 /* self css with NULL ->ss, points back to this cgroup */
488 struct cgroup_subsys_state self;
489
490 unsigned long flags; /* "unsigned long" so bitops work */
491
492 /*
493 * The depth this cgroup is at. The root is at depth zero and each
494 * step down the hierarchy increments the level. This along with
495 * ancestors[] can determine whether a given cgroup is a
496 * descendant of another without traversing the hierarchy.
497 */
498 int level;
499
500 /* Maximum allowed descent tree depth */
501 int max_depth;
502
503 /*
504 * Keep track of total numbers of visible and dying descent cgroups.
505 * Dying cgroups are cgroups which were deleted by a user,
506 * but are still existing because someone else is holding a reference.
507 * max_descendants is a maximum allowed number of descent cgroups.
508 *
509 * nr_descendants and nr_dying_descendants are protected
510 * by cgroup_mutex and css_set_lock. It's fine to read them holding
511 * any of cgroup_mutex and css_set_lock; for writing both locks
512 * should be held.
513 */
514 int nr_descendants;
515 int nr_dying_descendants;
516 int max_descendants;
517
518 /*
519 * Domain/threaded split of self.nr_populated_children: each counts
520 * immediate-child cgroups whose subtree is populated and sums to
521 * self.nr_populated_children. Kept as separate fields to allow readers
522 * like cgroup_can_be_thread_root() unlocked access. Protected by
523 * css_set_lock; updated by css_update_populated().
524 */
525 int nr_populated_domain_children;
526 int nr_populated_threaded_children;
527
528 int nr_threaded_children; /* # of live threaded child cgroups */
529
530 /*
531 * Sequence number for cgroup.kill. Incremented with both cgroup_mutex
532 * and css_set_lock held. Readers hold either one.
533 */
534 unsigned int kill_seq;
535
536 struct kernfs_node *kn; /* cgroup kernfs entry */
537 struct cgroup_file procs_file; /* handle for "cgroup.procs" */
538 struct cgroup_file events_file; /* handle for "cgroup.events" */
539
540 /* handles for "{cpu,memory,io,irq}.pressure" */
541 struct cgroup_file psi_files[NR_PSI_RESOURCES];
542
543 /*
544 * The bitmask of subsystems enabled on the child cgroups.
545 * ->subtree_control is the one configured through
546 * "cgroup.subtree_control" while ->subtree_ss_mask is the effective
547 * one which may have more subsystems enabled. Controller knobs
548 * are made available iff it's enabled in ->subtree_control.
549 */
550 u32 subtree_control;
551 u32 subtree_ss_mask;
552 u32 old_subtree_control;
553 u32 old_subtree_ss_mask;
554
555 /* Private pointers for each registered subsystem */
556 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
557
558 /*
559 * Keep track of total number of dying CSSes at and below this cgroup.
560 * Protected by cgroup_mutex.
561 */
562 int nr_dying_subsys[CGROUP_SUBSYS_COUNT];
563
564 struct cgroup_root *root;
565
566 /*
567 * List of cgrp_cset_links pointing at css_sets with tasks in this
568 * cgroup. Protected by css_set_lock.
569 */
570 struct list_head cset_links;
571
572 /*
573 * On the default hierarchy, a css_set for a cgroup with some
574 * susbsys disabled will point to css's which are associated with
575 * the closest ancestor which has the subsys enabled. The
576 * following lists all css_sets which point to this cgroup's css
577 * for the given subsystem.
578 */
579 struct list_head e_csets[CGROUP_SUBSYS_COUNT];
580
581 /*
582 * If !threaded, self. If threaded, it points to the nearest
583 * domain ancestor. Inside a threaded subtree, cgroups are exempt
584 * from process granularity and no-internal-task constraint.
585 * Domain level resource consumptions which aren't tied to a
586 * specific task are charged to the dom_cgrp.
587 */
588 struct cgroup *dom_cgrp;
589 struct cgroup *old_dom_cgrp; /* used while enabling threaded */
590
591 /*
592 * Depending on the context, this field is initialized via
593 * css_rstat_init() at different places:
594 *
595 * when cgroup is the root cgroup
596 * performed in cgroup_setup_root()
597 * otherwise
598 * performed in cgroup_create()
599 */
600 struct cgroup_rstat_base_cpu __percpu *rstat_base_cpu;
601
602 /*
603 * Add padding to keep the read mostly rstat per-cpu pointer on a
604 * different cacheline than the following *bstat fields which can have
605 * frequent updates.
606 */
607 CACHELINE_PADDING(_pad_);
608
609 /* cgroup basic resource statistics */
610 struct cgroup_base_stat last_bstat;
611 struct cgroup_base_stat bstat;
612 struct prev_cputime prev_cputime; /* for printing out cputime */
613
614 /*
615 * list of pidlists, up to two for each namespace (one for procs, one
616 * for tasks); created on demand.
617 */
618 struct list_head pidlists;
619 struct mutex pidlist_mutex;
620
621 /* used to wait for offlining of csses */
622 wait_queue_head_t offline_waitq;
623
624 /* used to schedule release agent */
625 struct work_struct release_agent_work;
626
627 /* used to track pressure stalls */
628 struct psi_group *psi;
629
630 /* used to store eBPF programs */
631 struct cgroup_bpf bpf;
632
633 /* Used to store internal freezer state */
634 struct cgroup_freezer_state freezer;
635
636 #ifdef CONFIG_BPF_SYSCALL
637 struct bpf_local_storage __rcu *bpf_cgrp_storage;
638 #endif
639 #ifdef CONFIG_EXT_SUB_SCHED
640 struct scx_sched __rcu *scx_sched;
641 #endif
642
643 /* All ancestors including self */
644 union {
645 DECLARE_FLEX_ARRAY(struct cgroup *, ancestors);
646 struct {
647 struct cgroup *_root_ancestor;
648 DECLARE_FLEX_ARRAY(struct cgroup *, _low_ancestors);
649 };
650 };
651 };
652
653 /*
654 * A cgroup_root represents the root of a cgroup hierarchy, and may be
655 * associated with a kernfs_root to form an active hierarchy. This is
656 * internal to cgroup core. Don't access directly from controllers.
657 */
658 struct cgroup_root {
659 struct kernfs_root *kf_root;
660
661 /* The bitmask of subsystems attached to this hierarchy */
662 unsigned int subsys_mask;
663
664 /* Unique id for this hierarchy. */
665 int hierarchy_id;
666
667 /* A list running through the active hierarchies */
668 struct list_head root_list;
669 struct rcu_head rcu; /* Must be near the top */
670
671 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
672 atomic_t nr_cgrps;
673
674 /* Hierarchy-specific flags */
675 unsigned int flags;
676
677 /* The path to use for release notifications. */
678 char release_agent_path[PATH_MAX];
679
680 /* The name for this hierarchy - may be empty */
681 char name[MAX_CGROUP_ROOT_NAMELEN];
682
683 /*
684 * The root cgroup. The containing cgroup_root will be destroyed on its
685 * release. This must be embedded last due to flexible array at the end
686 * of struct cgroup.
687 */
688 struct cgroup cgrp;
689 };
690
691 /*
692 * struct cftype: handler definitions for cgroup control files
693 *
694 * When reading/writing to a file:
695 * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
696 * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
697 */
698 struct cftype {
699 /*
700 * Name of the subsystem is prepended in cgroup_file_name().
701 * Zero length string indicates end of cftype array.
702 */
703 char name[MAX_CFTYPE_NAME];
704 unsigned long private;
705
706 /*
707 * The maximum length of string, excluding trailing nul, that can
708 * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
709 */
710 size_t max_write_len;
711
712 /* CFTYPE_* flags */
713 unsigned int flags;
714
715 /*
716 * If non-zero, should contain the offset from the start of css to
717 * a struct cgroup_file field. cgroup will record the handle of
718 * the created file into it. The recorded handle can be used as
719 * long as the containing css remains accessible.
720 */
721 unsigned int file_offset;
722
723 /*
724 * Fields used for internal bookkeeping. Initialized automatically
725 * during registration.
726 */
727 struct cgroup_subsys *ss; /* NULL for cgroup core files */
728 struct list_head node; /* anchored at ss->cfts */
729 struct kernfs_ops *kf_ops;
730
731 int (*open)(struct kernfs_open_file *of);
732 void (*release)(struct kernfs_open_file *of);
733
734 /*
735 * read_u64() is a shortcut for the common case of returning a
736 * single integer. Use it in place of read()
737 */
738 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
739 /*
740 * read_s64() is a signed version of read_u64()
741 */
742 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
743
744 /* generic seq_file read interface */
745 int (*seq_show)(struct seq_file *sf, void *v);
746
747 /* optional ops, implement all or none */
748 void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
749 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
750 void (*seq_stop)(struct seq_file *sf, void *v);
751
752 /*
753 * write_u64() is a shortcut for the common case of accepting
754 * a single integer (as parsed by simple_strtoull) from
755 * userspace. Use in place of write(); return 0 or error.
756 */
757 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
758 u64 val);
759 /*
760 * write_s64() is a signed version of write_u64()
761 */
762 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
763 s64 val);
764
765 /*
766 * write() is the generic write callback which maps directly to
767 * kernfs write operation and overrides all other operations.
768 * Maximum write size is determined by ->max_write_len. Use
769 * of_css/cft() to access the associated css and cft.
770 */
771 ssize_t (*write)(struct kernfs_open_file *of,
772 char *buf, size_t nbytes, loff_t off);
773
774 __poll_t (*poll)(struct kernfs_open_file *of,
775 struct poll_table_struct *pt);
776
777 struct lock_class_key lockdep_key;
778 };
779
780 /*
781 * Control Group subsystem type.
782 * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
783 */
784 struct cgroup_subsys {
785 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
786 int (*css_online)(struct cgroup_subsys_state *css);
787 void (*css_offline)(struct cgroup_subsys_state *css);
788 void (*css_released)(struct cgroup_subsys_state *css);
789 void (*css_free)(struct cgroup_subsys_state *css);
790 void (*css_reset)(struct cgroup_subsys_state *css);
791 void (*css_killed)(struct cgroup_subsys_state *css);
792 void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu);
793 int (*css_extra_stat_show)(struct seq_file *seq,
794 struct cgroup_subsys_state *css);
795 int (*css_local_stat_show)(struct seq_file *seq,
796 struct cgroup_subsys_state *css);
797
798 int (*can_attach)(struct cgroup_taskset *tset);
799 void (*cancel_attach)(struct cgroup_taskset *tset);
800 void (*attach)(struct cgroup_taskset *tset);
801 int (*can_fork)(struct task_struct *task,
802 struct css_set *cset);
803 void (*cancel_fork)(struct task_struct *task, struct css_set *cset);
804 void (*fork)(struct task_struct *task);
805 void (*exit)(struct task_struct *task);
806 void (*release)(struct task_struct *task);
807 void (*bind)(struct cgroup_subsys_state *root_css);
808
809 bool early_init:1;
810
811 /*
812 * If %true, the controller, on the default hierarchy, doesn't show
813 * up in "cgroup.controllers" or "cgroup.subtree_control", is
814 * implicitly enabled on all cgroups on the default hierarchy, and
815 * bypasses the "no internal process" constraint. This is for
816 * utility type controllers which is transparent to userland.
817 *
818 * An implicit controller can be stolen from the default hierarchy
819 * anytime and thus must be okay with offline csses from previous
820 * hierarchies coexisting with csses for the current one.
821 */
822 bool implicit_on_dfl:1;
823
824 /*
825 * If %true, the controller, supports threaded mode on the default
826 * hierarchy. In a threaded subtree, both process granularity and
827 * no-internal-process constraint are ignored and a threaded
828 * controllers should be able to handle that.
829 *
830 * Note that as an implicit controller is automatically enabled on
831 * all cgroups on the default hierarchy, it should also be
832 * threaded. implicit && !threaded is not supported.
833 */
834 bool threaded:1;
835
836 /* the following two fields are initialized automatically during boot */
837 int id;
838 const char *name;
839
840 /* optional, initialized automatically during boot if not set */
841 const char *legacy_name;
842
843 /* link to parent, protected by cgroup_lock() */
844 struct cgroup_root *root;
845
846 /* idr for css->id */
847 struct idr css_idr;
848
849 /*
850 * List of cftypes. Each entry is the first entry of an array
851 * terminated by zero length name.
852 */
853 struct list_head cfts;
854
855 /*
856 * Base cftypes which are automatically registered. The two can
857 * point to the same array.
858 */
859 struct cftype *dfl_cftypes; /* for the default hierarchy */
860 struct cftype *legacy_cftypes; /* for the legacy hierarchies */
861
862 /*
863 * A subsystem may depend on other subsystems. When such subsystem
864 * is enabled on a cgroup, the depended-upon subsystems are enabled
865 * together if available. Subsystems enabled due to dependency are
866 * not visible to userland until explicitly enabled. The following
867 * specifies the mask of subsystems that this one depends on.
868 */
869 unsigned int depends_on;
870
871 spinlock_t rstat_ss_lock;
872 struct llist_head __percpu *lhead; /* lockless update list head */
873 };
874
875 extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
876 extern bool cgroup_enable_per_threadgroup_rwsem;
877
878 struct cgroup_of_peak {
879 unsigned long value;
880 struct list_head list;
881 };
882
883 /**
884 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
885 * @tsk: target task
886 *
887 * Allows cgroup operations to synchronize against threadgroup changes
888 * using a global percpu_rw_semaphore and a per threadgroup rw_semaphore when
889 * favordynmods is on. See the comment above CGRP_ROOT_FAVOR_DYNMODS definition.
890 */
cgroup_threadgroup_change_begin(struct task_struct * tsk)891 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
892 {
893 percpu_down_read(&cgroup_threadgroup_rwsem);
894 if (cgroup_enable_per_threadgroup_rwsem)
895 down_read(&tsk->signal->cgroup_threadgroup_rwsem);
896 }
897
898 /**
899 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
900 * @tsk: target task
901 *
902 * Counterpart of cgroup_threadgroup_change_begin().
903 */
cgroup_threadgroup_change_end(struct task_struct * tsk)904 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
905 {
906 if (cgroup_enable_per_threadgroup_rwsem)
907 up_read(&tsk->signal->cgroup_threadgroup_rwsem);
908 percpu_up_read(&cgroup_threadgroup_rwsem);
909 }
910
911 #else /* CONFIG_CGROUPS */
912
913 #define CGROUP_SUBSYS_COUNT 0
914
cgroup_threadgroup_change_begin(struct task_struct * tsk)915 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
916 {
917 might_sleep();
918 }
919
cgroup_threadgroup_change_end(struct task_struct * tsk)920 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
921
922 #endif /* CONFIG_CGROUPS */
923
924 #ifdef CONFIG_SOCK_CGROUP_DATA
925
926 /*
927 * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
928 * per-socket cgroup information except for memcg association.
929 *
930 * On legacy hierarchies, net_prio and net_cls controllers directly
931 * set attributes on each sock which can then be tested by the network
932 * layer. On the default hierarchy, each sock is associated with the
933 * cgroup it was created in and the networking layer can match the
934 * cgroup directly.
935 */
936 struct sock_cgroup_data {
937 struct cgroup *cgroup; /* v2 */
938 #ifdef CONFIG_CGROUP_NET_CLASSID
939 u32 classid; /* v1 */
940 #endif
941 #ifdef CONFIG_CGROUP_NET_PRIO
942 u16 prioidx; /* v1 */
943 #endif
944 };
945
sock_cgroup_prioidx(const struct sock_cgroup_data * skcd)946 static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
947 {
948 #ifdef CONFIG_CGROUP_NET_PRIO
949 return READ_ONCE(skcd->prioidx);
950 #else
951 return 1;
952 #endif
953 }
954
955 #ifdef CONFIG_CGROUP_NET_CLASSID
sock_cgroup_classid(const struct sock_cgroup_data * skcd)956 static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
957 {
958 return READ_ONCE(skcd->classid);
959 }
960 #endif
961
sock_cgroup_set_prioidx(struct sock_cgroup_data * skcd,u16 prioidx)962 static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
963 u16 prioidx)
964 {
965 #ifdef CONFIG_CGROUP_NET_PRIO
966 WRITE_ONCE(skcd->prioidx, prioidx);
967 #endif
968 }
969
970 #ifdef CONFIG_CGROUP_NET_CLASSID
sock_cgroup_set_classid(struct sock_cgroup_data * skcd,u32 classid)971 static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
972 u32 classid)
973 {
974 WRITE_ONCE(skcd->classid, classid);
975 }
976 #endif
977
978 #else /* CONFIG_SOCK_CGROUP_DATA */
979
980 struct sock_cgroup_data {
981 };
982
983 #endif /* CONFIG_SOCK_CGROUP_DATA */
984
985 #endif /* _LINUX_CGROUP_DEFS_H */
986