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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.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 : :
76 : : /* cgroup_root->flags */
77 : : enum {
78 : : CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
79 : : CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
80 : :
81 : : /*
82 : : * Consider namespaces as delegation boundaries. If this flag is
83 : : * set, controller specific interface files in a namespace root
84 : : * aren't writeable from inside the namespace.
85 : : */
86 : : CGRP_ROOT_NS_DELEGATE = (1 << 3),
87 : :
88 : : /*
89 : : * Enable cpuset controller in v1 cgroup to use v2 behavior.
90 : : */
91 : : CGRP_ROOT_CPUSET_V2_MODE = (1 << 4),
92 : :
93 : : /*
94 : : * Enable legacy local memory.events.
95 : : */
96 : : CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 5),
97 : : };
98 : :
99 : : /* cftype->flags */
100 : : enum {
101 : : CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
102 : : CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
103 : : CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */
104 : :
105 : : CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
106 : : CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
107 : : CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */
108 : :
109 : : /* internal flags, do not use outside cgroup core proper */
110 : : __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
111 : : __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
112 : : };
113 : :
114 : : /*
115 : : * cgroup_file is the handle for a file instance created in a cgroup which
116 : : * is used, for example, to generate file changed notifications. This can
117 : : * be obtained by setting cftype->file_offset.
118 : : */
119 : : struct cgroup_file {
120 : : /* do not access any fields from outside cgroup core */
121 : : struct kernfs_node *kn;
122 : : unsigned long notified_at;
123 : : struct timer_list notify_timer;
124 : : };
125 : :
126 : : /*
127 : : * Per-subsystem/per-cgroup state maintained by the system. This is the
128 : : * fundamental structural building block that controllers deal with.
129 : : *
130 : : * Fields marked with "PI:" are public and immutable and may be accessed
131 : : * directly without synchronization.
132 : : */
133 : : struct cgroup_subsys_state {
134 : : /* PI: the cgroup that this css is attached to */
135 : : struct cgroup *cgroup;
136 : :
137 : : /* PI: the cgroup subsystem that this css is attached to */
138 : : struct cgroup_subsys *ss;
139 : :
140 : : /* reference count - access via css_[try]get() and css_put() */
141 : : struct percpu_ref refcnt;
142 : :
143 : : /* siblings list anchored at the parent's ->children */
144 : : struct list_head sibling;
145 : : struct list_head children;
146 : :
147 : : /* flush target list anchored at cgrp->rstat_css_list */
148 : : struct list_head rstat_css_node;
149 : :
150 : : /*
151 : : * PI: Subsys-unique ID. 0 is unused and root is always 1. The
152 : : * matching css can be looked up using css_from_id().
153 : : */
154 : : int id;
155 : :
156 : : unsigned int flags;
157 : :
158 : : /*
159 : : * Monotonically increasing unique serial number which defines a
160 : : * uniform order among all csses. It's guaranteed that all
161 : : * ->children lists are in the ascending order of ->serial_nr and
162 : : * used to allow interrupting and resuming iterations.
163 : : */
164 : : u64 serial_nr;
165 : :
166 : : /*
167 : : * Incremented by online self and children. Used to guarantee that
168 : : * parents are not offlined before their children.
169 : : */
170 : : atomic_t online_cnt;
171 : :
172 : : /* percpu_ref killing and RCU release */
173 : : struct work_struct destroy_work;
174 : : struct rcu_work destroy_rwork;
175 : :
176 : : /*
177 : : * PI: the parent css. Placed here for cache proximity to following
178 : : * fields of the containing structure.
179 : : */
180 : : struct cgroup_subsys_state *parent;
181 : : };
182 : :
183 : : /*
184 : : * A css_set is a structure holding pointers to a set of
185 : : * cgroup_subsys_state objects. This saves space in the task struct
186 : : * object and speeds up fork()/exit(), since a single inc/dec and a
187 : : * list_add()/del() can bump the reference count on the entire cgroup
188 : : * set for a task.
189 : : */
190 : : struct css_set {
191 : : /*
192 : : * Set of subsystem states, one for each subsystem. This array is
193 : : * immutable after creation apart from the init_css_set during
194 : : * subsystem registration (at boot time).
195 : : */
196 : : struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
197 : :
198 : : /* reference count */
199 : : refcount_t refcount;
200 : :
201 : : /*
202 : : * For a domain cgroup, the following points to self. If threaded,
203 : : * to the matching cset of the nearest domain ancestor. The
204 : : * dom_cset provides access to the domain cgroup and its csses to
205 : : * which domain level resource consumptions should be charged.
206 : : */
207 : : struct css_set *dom_cset;
208 : :
209 : : /* the default cgroup associated with this css_set */
210 : : struct cgroup *dfl_cgrp;
211 : :
212 : : /* internal task count, protected by css_set_lock */
213 : : int nr_tasks;
214 : :
215 : : /*
216 : : * Lists running through all tasks using this cgroup group.
217 : : * mg_tasks lists tasks which belong to this cset but are in the
218 : : * process of being migrated out or in. Protected by
219 : : * css_set_rwsem, but, during migration, once tasks are moved to
220 : : * mg_tasks, it can be read safely while holding cgroup_mutex.
221 : : */
222 : : struct list_head tasks;
223 : : struct list_head mg_tasks;
224 : : struct list_head dying_tasks;
225 : :
226 : : /* all css_task_iters currently walking this cset */
227 : : struct list_head task_iters;
228 : :
229 : : /*
230 : : * On the default hierarhcy, ->subsys[ssid] may point to a css
231 : : * attached to an ancestor instead of the cgroup this css_set is
232 : : * associated with. The following node is anchored at
233 : : * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
234 : : * iterate through all css's attached to a given cgroup.
235 : : */
236 : : struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
237 : :
238 : : /* all threaded csets whose ->dom_cset points to this cset */
239 : : struct list_head threaded_csets;
240 : : struct list_head threaded_csets_node;
241 : :
242 : : /*
243 : : * List running through all cgroup groups in the same hash
244 : : * slot. Protected by css_set_lock
245 : : */
246 : : struct hlist_node hlist;
247 : :
248 : : /*
249 : : * List of cgrp_cset_links pointing at cgroups referenced from this
250 : : * css_set. Protected by css_set_lock.
251 : : */
252 : : struct list_head cgrp_links;
253 : :
254 : : /*
255 : : * List of csets participating in the on-going migration either as
256 : : * source or destination. Protected by cgroup_mutex.
257 : : */
258 : : struct list_head mg_preload_node;
259 : : struct list_head mg_node;
260 : :
261 : : /*
262 : : * If this cset is acting as the source of migration the following
263 : : * two fields are set. mg_src_cgrp and mg_dst_cgrp are
264 : : * respectively the source and destination cgroups of the on-going
265 : : * migration. mg_dst_cset is the destination cset the target tasks
266 : : * on this cset should be migrated to. Protected by cgroup_mutex.
267 : : */
268 : : struct cgroup *mg_src_cgrp;
269 : : struct cgroup *mg_dst_cgrp;
270 : : struct css_set *mg_dst_cset;
271 : :
272 : : /* dead and being drained, ignore for migration */
273 : : bool dead;
274 : :
275 : : /* For RCU-protected deletion */
276 : : struct rcu_head rcu_head;
277 : : };
278 : :
279 : : struct cgroup_base_stat {
280 : : struct task_cputime cputime;
281 : : };
282 : :
283 : : /*
284 : : * rstat - cgroup scalable recursive statistics. Accounting is done
285 : : * per-cpu in cgroup_rstat_cpu which is then lazily propagated up the
286 : : * hierarchy on reads.
287 : : *
288 : : * When a stat gets updated, the cgroup_rstat_cpu and its ancestors are
289 : : * linked into the updated tree. On the following read, propagation only
290 : : * considers and consumes the updated tree. This makes reading O(the
291 : : * number of descendants which have been active since last read) instead of
292 : : * O(the total number of descendants).
293 : : *
294 : : * This is important because there can be a lot of (draining) cgroups which
295 : : * aren't active and stat may be read frequently. The combination can
296 : : * become very expensive. By propagating selectively, increasing reading
297 : : * frequency decreases the cost of each read.
298 : : *
299 : : * This struct hosts both the fields which implement the above -
300 : : * updated_children and updated_next - and the fields which track basic
301 : : * resource statistics on top of it - bsync, bstat and last_bstat.
302 : : */
303 : : struct cgroup_rstat_cpu {
304 : : /*
305 : : * ->bsync protects ->bstat. These are the only fields which get
306 : : * updated in the hot path.
307 : : */
308 : : struct u64_stats_sync bsync;
309 : : struct cgroup_base_stat bstat;
310 : :
311 : : /*
312 : : * Snapshots at the last reading. These are used to calculate the
313 : : * deltas to propagate to the global counters.
314 : : */
315 : : struct cgroup_base_stat last_bstat;
316 : :
317 : : /*
318 : : * Child cgroups with stat updates on this cpu since the last read
319 : : * are linked on the parent's ->updated_children through
320 : : * ->updated_next.
321 : : *
322 : : * In addition to being more compact, singly-linked list pointing
323 : : * to the cgroup makes it unnecessary for each per-cpu struct to
324 : : * point back to the associated cgroup.
325 : : *
326 : : * Protected by per-cpu cgroup_rstat_cpu_lock.
327 : : */
328 : : struct cgroup *updated_children; /* terminated by self cgroup */
329 : : struct cgroup *updated_next; /* NULL iff not on the list */
330 : : };
331 : :
332 : : struct cgroup_freezer_state {
333 : : /* Should the cgroup and its descendants be frozen. */
334 : : bool freeze;
335 : :
336 : : /* Should the cgroup actually be frozen? */
337 : : int e_freeze;
338 : :
339 : : /* Fields below are protected by css_set_lock */
340 : :
341 : : /* Number of frozen descendant cgroups */
342 : : int nr_frozen_descendants;
343 : :
344 : : /*
345 : : * Number of tasks, which are counted as frozen:
346 : : * frozen, SIGSTOPped, and PTRACEd.
347 : : */
348 : : int nr_frozen_tasks;
349 : : };
350 : :
351 : : struct cgroup {
352 : : /* self css with NULL ->ss, points back to this cgroup */
353 : : struct cgroup_subsys_state self;
354 : :
355 : : unsigned long flags; /* "unsigned long" so bitops work */
356 : :
357 : : /*
358 : : * idr allocated in-hierarchy ID.
359 : : *
360 : : * ID 0 is not used, the ID of the root cgroup is always 1, and a
361 : : * new cgroup will be assigned with a smallest available ID.
362 : : *
363 : : * Allocating/Removing ID must be protected by cgroup_mutex.
364 : : */
365 : : int id;
366 : :
367 : : /*
368 : : * The depth this cgroup is at. The root is at depth zero and each
369 : : * step down the hierarchy increments the level. This along with
370 : : * ancestor_ids[] can determine whether a given cgroup is a
371 : : * descendant of another without traversing the hierarchy.
372 : : */
373 : : int level;
374 : :
375 : : /* Maximum allowed descent tree depth */
376 : : int max_depth;
377 : :
378 : : /*
379 : : * Keep track of total numbers of visible and dying descent cgroups.
380 : : * Dying cgroups are cgroups which were deleted by a user,
381 : : * but are still existing because someone else is holding a reference.
382 : : * max_descendants is a maximum allowed number of descent cgroups.
383 : : *
384 : : * nr_descendants and nr_dying_descendants are protected
385 : : * by cgroup_mutex and css_set_lock. It's fine to read them holding
386 : : * any of cgroup_mutex and css_set_lock; for writing both locks
387 : : * should be held.
388 : : */
389 : : int nr_descendants;
390 : : int nr_dying_descendants;
391 : : int max_descendants;
392 : :
393 : : /*
394 : : * Each non-empty css_set associated with this cgroup contributes
395 : : * one to nr_populated_csets. The counter is zero iff this cgroup
396 : : * doesn't have any tasks.
397 : : *
398 : : * All children which have non-zero nr_populated_csets and/or
399 : : * nr_populated_children of their own contribute one to either
400 : : * nr_populated_domain_children or nr_populated_threaded_children
401 : : * depending on their type. Each counter is zero iff all cgroups
402 : : * of the type in the subtree proper don't have any tasks.
403 : : */
404 : : int nr_populated_csets;
405 : : int nr_populated_domain_children;
406 : : int nr_populated_threaded_children;
407 : :
408 : : int nr_threaded_children; /* # of live threaded child cgroups */
409 : :
410 : : struct kernfs_node *kn; /* cgroup kernfs entry */
411 : : struct cgroup_file procs_file; /* handle for "cgroup.procs" */
412 : : struct cgroup_file events_file; /* handle for "cgroup.events" */
413 : :
414 : : /*
415 : : * The bitmask of subsystems enabled on the child cgroups.
416 : : * ->subtree_control is the one configured through
417 : : * "cgroup.subtree_control" while ->child_ss_mask is the effective
418 : : * one which may have more subsystems enabled. Controller knobs
419 : : * are made available iff it's enabled in ->subtree_control.
420 : : */
421 : : u16 subtree_control;
422 : : u16 subtree_ss_mask;
423 : : u16 old_subtree_control;
424 : : u16 old_subtree_ss_mask;
425 : :
426 : : /* Private pointers for each registered subsystem */
427 : : struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
428 : :
429 : : struct cgroup_root *root;
430 : :
431 : : /*
432 : : * List of cgrp_cset_links pointing at css_sets with tasks in this
433 : : * cgroup. Protected by css_set_lock.
434 : : */
435 : : struct list_head cset_links;
436 : :
437 : : /*
438 : : * On the default hierarchy, a css_set for a cgroup with some
439 : : * susbsys disabled will point to css's which are associated with
440 : : * the closest ancestor which has the subsys enabled. The
441 : : * following lists all css_sets which point to this cgroup's css
442 : : * for the given subsystem.
443 : : */
444 : : struct list_head e_csets[CGROUP_SUBSYS_COUNT];
445 : :
446 : : /*
447 : : * If !threaded, self. If threaded, it points to the nearest
448 : : * domain ancestor. Inside a threaded subtree, cgroups are exempt
449 : : * from process granularity and no-internal-task constraint.
450 : : * Domain level resource consumptions which aren't tied to a
451 : : * specific task are charged to the dom_cgrp.
452 : : */
453 : : struct cgroup *dom_cgrp;
454 : : struct cgroup *old_dom_cgrp; /* used while enabling threaded */
455 : :
456 : : /* per-cpu recursive resource statistics */
457 : : struct cgroup_rstat_cpu __percpu *rstat_cpu;
458 : : struct list_head rstat_css_list;
459 : :
460 : : /* cgroup basic resource statistics */
461 : : struct cgroup_base_stat pending_bstat; /* pending from children */
462 : : struct cgroup_base_stat bstat;
463 : : struct prev_cputime prev_cputime; /* for printing out cputime */
464 : :
465 : : /*
466 : : * list of pidlists, up to two for each namespace (one for procs, one
467 : : * for tasks); created on demand.
468 : : */
469 : : struct list_head pidlists;
470 : : struct mutex pidlist_mutex;
471 : :
472 : : /* used to wait for offlining of csses */
473 : : wait_queue_head_t offline_waitq;
474 : :
475 : : /* used to schedule release agent */
476 : : struct work_struct release_agent_work;
477 : :
478 : : /* used to track pressure stalls */
479 : : struct psi_group psi;
480 : :
481 : : /* used to store eBPF programs */
482 : : struct cgroup_bpf bpf;
483 : :
484 : : /* If there is block congestion on this cgroup. */
485 : : atomic_t congestion_count;
486 : :
487 : : /* Used to store internal freezer state */
488 : : struct cgroup_freezer_state freezer;
489 : :
490 : : /* ids of the ancestors at each level including self */
491 : : int ancestor_ids[];
492 : : };
493 : :
494 : : /*
495 : : * A cgroup_root represents the root of a cgroup hierarchy, and may be
496 : : * associated with a kernfs_root to form an active hierarchy. This is
497 : : * internal to cgroup core. Don't access directly from controllers.
498 : : */
499 : : struct cgroup_root {
500 : : struct kernfs_root *kf_root;
501 : :
502 : : /* The bitmask of subsystems attached to this hierarchy */
503 : : unsigned int subsys_mask;
504 : :
505 : : /* Unique id for this hierarchy. */
506 : : int hierarchy_id;
507 : :
508 : : /* The root cgroup. Root is destroyed on its release. */
509 : : struct cgroup cgrp;
510 : :
511 : : /* for cgrp->ancestor_ids[0] */
512 : : int cgrp_ancestor_id_storage;
513 : :
514 : : /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
515 : : atomic_t nr_cgrps;
516 : :
517 : : /* A list running through the active hierarchies */
518 : : struct list_head root_list;
519 : :
520 : : /* Hierarchy-specific flags */
521 : : unsigned int flags;
522 : :
523 : : /* IDs for cgroups in this hierarchy */
524 : : struct idr cgroup_idr;
525 : :
526 : : /* The path to use for release notifications. */
527 : : char release_agent_path[PATH_MAX];
528 : :
529 : : /* The name for this hierarchy - may be empty */
530 : : char name[MAX_CGROUP_ROOT_NAMELEN];
531 : : };
532 : :
533 : : /*
534 : : * struct cftype: handler definitions for cgroup control files
535 : : *
536 : : * When reading/writing to a file:
537 : : * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
538 : : * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
539 : : */
540 : : struct cftype {
541 : : /*
542 : : * By convention, the name should begin with the name of the
543 : : * subsystem, followed by a period. Zero length string indicates
544 : : * end of cftype array.
545 : : */
546 : : char name[MAX_CFTYPE_NAME];
547 : : unsigned long private;
548 : :
549 : : /*
550 : : * The maximum length of string, excluding trailing nul, that can
551 : : * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
552 : : */
553 : : size_t max_write_len;
554 : :
555 : : /* CFTYPE_* flags */
556 : : unsigned int flags;
557 : :
558 : : /*
559 : : * If non-zero, should contain the offset from the start of css to
560 : : * a struct cgroup_file field. cgroup will record the handle of
561 : : * the created file into it. The recorded handle can be used as
562 : : * long as the containing css remains accessible.
563 : : */
564 : : unsigned int file_offset;
565 : :
566 : : /*
567 : : * Fields used for internal bookkeeping. Initialized automatically
568 : : * during registration.
569 : : */
570 : : struct cgroup_subsys *ss; /* NULL for cgroup core files */
571 : : struct list_head node; /* anchored at ss->cfts */
572 : : struct kernfs_ops *kf_ops;
573 : :
574 : : int (*open)(struct kernfs_open_file *of);
575 : : void (*release)(struct kernfs_open_file *of);
576 : :
577 : : /*
578 : : * read_u64() is a shortcut for the common case of returning a
579 : : * single integer. Use it in place of read()
580 : : */
581 : : u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
582 : : /*
583 : : * read_s64() is a signed version of read_u64()
584 : : */
585 : : s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
586 : :
587 : : /* generic seq_file read interface */
588 : : int (*seq_show)(struct seq_file *sf, void *v);
589 : :
590 : : /* optional ops, implement all or none */
591 : : void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
592 : : void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
593 : : void (*seq_stop)(struct seq_file *sf, void *v);
594 : :
595 : : /*
596 : : * write_u64() is a shortcut for the common case of accepting
597 : : * a single integer (as parsed by simple_strtoull) from
598 : : * userspace. Use in place of write(); return 0 or error.
599 : : */
600 : : int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
601 : : u64 val);
602 : : /*
603 : : * write_s64() is a signed version of write_u64()
604 : : */
605 : : int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
606 : : s64 val);
607 : :
608 : : /*
609 : : * write() is the generic write callback which maps directly to
610 : : * kernfs write operation and overrides all other operations.
611 : : * Maximum write size is determined by ->max_write_len. Use
612 : : * of_css/cft() to access the associated css and cft.
613 : : */
614 : : ssize_t (*write)(struct kernfs_open_file *of,
615 : : char *buf, size_t nbytes, loff_t off);
616 : :
617 : : __poll_t (*poll)(struct kernfs_open_file *of,
618 : : struct poll_table_struct *pt);
619 : :
620 : : #ifdef CONFIG_DEBUG_LOCK_ALLOC
621 : : struct lock_class_key lockdep_key;
622 : : #endif
623 : : };
624 : :
625 : : /*
626 : : * Control Group subsystem type.
627 : : * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
628 : : */
629 : : struct cgroup_subsys {
630 : : struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
631 : : int (*css_online)(struct cgroup_subsys_state *css);
632 : : void (*css_offline)(struct cgroup_subsys_state *css);
633 : : void (*css_released)(struct cgroup_subsys_state *css);
634 : : void (*css_free)(struct cgroup_subsys_state *css);
635 : : void (*css_reset)(struct cgroup_subsys_state *css);
636 : : void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu);
637 : : int (*css_extra_stat_show)(struct seq_file *seq,
638 : : struct cgroup_subsys_state *css);
639 : :
640 : : int (*can_attach)(struct cgroup_taskset *tset);
641 : : void (*cancel_attach)(struct cgroup_taskset *tset);
642 : : void (*attach)(struct cgroup_taskset *tset);
643 : : void (*post_attach)(void);
644 : : int (*can_fork)(struct task_struct *task);
645 : : void (*cancel_fork)(struct task_struct *task);
646 : : void (*fork)(struct task_struct *task);
647 : : void (*exit)(struct task_struct *task);
648 : : void (*release)(struct task_struct *task);
649 : : void (*bind)(struct cgroup_subsys_state *root_css);
650 : :
651 : : bool early_init:1;
652 : :
653 : : /*
654 : : * If %true, the controller, on the default hierarchy, doesn't show
655 : : * up in "cgroup.controllers" or "cgroup.subtree_control", is
656 : : * implicitly enabled on all cgroups on the default hierarchy, and
657 : : * bypasses the "no internal process" constraint. This is for
658 : : * utility type controllers which is transparent to userland.
659 : : *
660 : : * An implicit controller can be stolen from the default hierarchy
661 : : * anytime and thus must be okay with offline csses from previous
662 : : * hierarchies coexisting with csses for the current one.
663 : : */
664 : : bool implicit_on_dfl:1;
665 : :
666 : : /*
667 : : * If %true, the controller, supports threaded mode on the default
668 : : * hierarchy. In a threaded subtree, both process granularity and
669 : : * no-internal-process constraint are ignored and a threaded
670 : : * controllers should be able to handle that.
671 : : *
672 : : * Note that as an implicit controller is automatically enabled on
673 : : * all cgroups on the default hierarchy, it should also be
674 : : * threaded. implicit && !threaded is not supported.
675 : : */
676 : : bool threaded:1;
677 : :
678 : : /*
679 : : * If %false, this subsystem is properly hierarchical -
680 : : * configuration, resource accounting and restriction on a parent
681 : : * cgroup cover those of its children. If %true, hierarchy support
682 : : * is broken in some ways - some subsystems ignore hierarchy
683 : : * completely while others are only implemented half-way.
684 : : *
685 : : * It's now disallowed to create nested cgroups if the subsystem is
686 : : * broken and cgroup core will emit a warning message on such
687 : : * cases. Eventually, all subsystems will be made properly
688 : : * hierarchical and this will go away.
689 : : */
690 : : bool broken_hierarchy:1;
691 : : bool warned_broken_hierarchy:1;
692 : :
693 : : /* the following two fields are initialized automtically during boot */
694 : : int id;
695 : : const char *name;
696 : :
697 : : /* optional, initialized automatically during boot if not set */
698 : : const char *legacy_name;
699 : :
700 : : /* link to parent, protected by cgroup_lock() */
701 : : struct cgroup_root *root;
702 : :
703 : : /* idr for css->id */
704 : : struct idr css_idr;
705 : :
706 : : /*
707 : : * List of cftypes. Each entry is the first entry of an array
708 : : * terminated by zero length name.
709 : : */
710 : : struct list_head cfts;
711 : :
712 : : /*
713 : : * Base cftypes which are automatically registered. The two can
714 : : * point to the same array.
715 : : */
716 : : struct cftype *dfl_cftypes; /* for the default hierarchy */
717 : : struct cftype *legacy_cftypes; /* for the legacy hierarchies */
718 : :
719 : : /*
720 : : * A subsystem may depend on other subsystems. When such subsystem
721 : : * is enabled on a cgroup, the depended-upon subsystems are enabled
722 : : * together if available. Subsystems enabled due to dependency are
723 : : * not visible to userland until explicitly enabled. The following
724 : : * specifies the mask of subsystems that this one depends on.
725 : : */
726 : : unsigned int depends_on;
727 : : };
728 : :
729 : : extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
730 : :
731 : : /**
732 : : * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
733 : : * @tsk: target task
734 : : *
735 : : * Allows cgroup operations to synchronize against threadgroup changes
736 : : * using a percpu_rw_semaphore.
737 : : */
738 : : static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
739 : : {
740 : 369129 : percpu_down_read(&cgroup_threadgroup_rwsem);
741 : : }
742 : :
743 : : /**
744 : : * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
745 : : * @tsk: target task
746 : : *
747 : : * Counterpart of cgroup_threadcgroup_change_begin().
748 : : */
749 : : static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
750 : : {
751 : 369309 : percpu_up_read(&cgroup_threadgroup_rwsem);
752 : : }
753 : :
754 : : #else /* CONFIG_CGROUPS */
755 : :
756 : : #define CGROUP_SUBSYS_COUNT 0
757 : :
758 : : static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
759 : : {
760 : : might_sleep();
761 : : }
762 : :
763 : : static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
764 : :
765 : : #endif /* CONFIG_CGROUPS */
766 : :
767 : : #ifdef CONFIG_SOCK_CGROUP_DATA
768 : :
769 : : /*
770 : : * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
771 : : * per-socket cgroup information except for memcg association.
772 : : *
773 : : * On legacy hierarchies, net_prio and net_cls controllers directly set
774 : : * attributes on each sock which can then be tested by the network layer.
775 : : * On the default hierarchy, each sock is associated with the cgroup it was
776 : : * created in and the networking layer can match the cgroup directly.
777 : : *
778 : : * To avoid carrying all three cgroup related fields separately in sock,
779 : : * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer.
780 : : * On boot, sock_cgroup_data records the cgroup that the sock was created
781 : : * in so that cgroup2 matches can be made; however, once either net_prio or
782 : : * net_cls starts being used, the area is overriden to carry prioidx and/or
783 : : * classid. The two modes are distinguished by whether the lowest bit is
784 : : * set. Clear bit indicates cgroup pointer while set bit prioidx and
785 : : * classid.
786 : : *
787 : : * While userland may start using net_prio or net_cls at any time, once
788 : : * either is used, cgroup2 matching no longer works. There is no reason to
789 : : * mix the two and this is in line with how legacy and v2 compatibility is
790 : : * handled. On mode switch, cgroup references which are already being
791 : : * pointed to by socks may be leaked. While this can be remedied by adding
792 : : * synchronization around sock_cgroup_data, given that the number of leaked
793 : : * cgroups is bound and highly unlikely to be high, this seems to be the
794 : : * better trade-off.
795 : : */
796 : : struct sock_cgroup_data {
797 : : union {
798 : : #ifdef __LITTLE_ENDIAN
799 : : struct {
800 : : u8 is_data : 1;
801 : : u8 no_refcnt : 1;
802 : : u8 unused : 6;
803 : : u8 padding;
804 : : u16 prioidx;
805 : : u32 classid;
806 : : } __packed;
807 : : #else
808 : : struct {
809 : : u32 classid;
810 : : u16 prioidx;
811 : : u8 padding;
812 : : u8 unused : 6;
813 : : u8 no_refcnt : 1;
814 : : u8 is_data : 1;
815 : : } __packed;
816 : : #endif
817 : : u64 val;
818 : : };
819 : : };
820 : :
821 : : /*
822 : : * There's a theoretical window where the following accessors race with
823 : : * updaters and return part of the previous pointer as the prioidx or
824 : : * classid. Such races are short-lived and the result isn't critical.
825 : : */
826 : : static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
827 : : {
828 : : /* fallback to 1 which is always the ID of the root cgroup */
829 [ - + ]: 223271 : return (skcd->is_data & 1) ? skcd->prioidx : 1;
830 : : }
831 : :
832 : : static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
833 : : {
834 : : /* fallback to 0 which is the unconfigured default classid */
835 [ - + ]: 223278 : return (skcd->is_data & 1) ? skcd->classid : 0;
836 : : }
837 : :
838 : : /*
839 : : * If invoked concurrently, the updaters may clobber each other. The
840 : : * caller is responsible for synchronization.
841 : : */
842 : 223271 : static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
843 : : u16 prioidx)
844 : : {
845 : 223271 : struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
846 : :
847 [ - + ]: 223271 : if (sock_cgroup_prioidx(&skcd_buf) == prioidx)
848 : 223271 : return;
849 : :
850 [ # # ]: 0 : if (!(skcd_buf.is_data & 1)) {
851 : 0 : skcd_buf.val = 0;
852 : 0 : skcd_buf.is_data = 1;
853 : : }
854 : :
855 : 0 : skcd_buf.prioidx = prioidx;
856 : 0 : WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */
857 : : }
858 : :
859 : 223278 : static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
860 : : u32 classid)
861 : : {
862 : 223278 : struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
863 : :
864 [ - + ]: 223278 : if (sock_cgroup_classid(&skcd_buf) == classid)
865 : 223278 : return;
866 : :
867 [ # # ]: 0 : if (!(skcd_buf.is_data & 1)) {
868 : 0 : skcd_buf.val = 0;
869 : 0 : skcd_buf.is_data = 1;
870 : : }
871 : :
872 : 0 : skcd_buf.classid = classid;
873 : 0 : WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */
874 : : }
875 : :
876 : : #else /* CONFIG_SOCK_CGROUP_DATA */
877 : :
878 : : struct sock_cgroup_data {
879 : : };
880 : :
881 : : #endif /* CONFIG_SOCK_CGROUP_DATA */
882 : :
883 : : #endif /* _LINUX_CGROUP_DEFS_H */
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