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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 : * Enable recursive subtree protection
100 : */
101 : CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 6),
102 : };
103 :
104 : /* cftype->flags */
105 : enum {
106 : CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
107 : CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
108 : CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */
109 :
110 : CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
111 : CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
112 : CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */
113 :
114 : /* internal flags, do not use outside cgroup core proper */
115 : __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
116 : __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
117 : };
118 :
119 : /*
120 : * cgroup_file is the handle for a file instance created in a cgroup which
121 : * is used, for example, to generate file changed notifications. This can
122 : * be obtained by setting cftype->file_offset.
123 : */
124 : struct cgroup_file {
125 : /* do not access any fields from outside cgroup core */
126 : struct kernfs_node *kn;
127 : unsigned long notified_at;
128 : struct timer_list notify_timer;
129 : };
130 :
131 : /*
132 : * Per-subsystem/per-cgroup state maintained by the system. This is the
133 : * fundamental structural building block that controllers deal with.
134 : *
135 : * Fields marked with "PI:" are public and immutable and may be accessed
136 : * directly without synchronization.
137 : */
138 : struct cgroup_subsys_state {
139 : /* PI: the cgroup that this css is attached to */
140 : struct cgroup *cgroup;
141 :
142 : /* PI: the cgroup subsystem that this css is attached to */
143 : struct cgroup_subsys *ss;
144 :
145 : /* reference count - access via css_[try]get() and css_put() */
146 : struct percpu_ref refcnt;
147 :
148 : /* siblings list anchored at the parent's ->children */
149 : struct list_head sibling;
150 : struct list_head children;
151 :
152 : /* flush target list anchored at cgrp->rstat_css_list */
153 : struct list_head rstat_css_node;
154 :
155 : /*
156 : * PI: Subsys-unique ID. 0 is unused and root is always 1. The
157 : * matching css can be looked up using css_from_id().
158 : */
159 : int id;
160 :
161 : unsigned int flags;
162 :
163 : /*
164 : * Monotonically increasing unique serial number which defines a
165 : * uniform order among all csses. It's guaranteed that all
166 : * ->children lists are in the ascending order of ->serial_nr and
167 : * used to allow interrupting and resuming iterations.
168 : */
169 : u64 serial_nr;
170 :
171 : /*
172 : * Incremented by online self and children. Used to guarantee that
173 : * parents are not offlined before their children.
174 : */
175 : atomic_t online_cnt;
176 :
177 : /* percpu_ref killing and RCU release */
178 : struct work_struct destroy_work;
179 : struct rcu_work destroy_rwork;
180 :
181 : /*
182 : * PI: the parent css. Placed here for cache proximity to following
183 : * fields of the containing structure.
184 : */
185 : struct cgroup_subsys_state *parent;
186 : };
187 :
188 : /*
189 : * A css_set is a structure holding pointers to a set of
190 : * cgroup_subsys_state objects. This saves space in the task struct
191 : * object and speeds up fork()/exit(), since a single inc/dec and a
192 : * list_add()/del() can bump the reference count on the entire cgroup
193 : * set for a task.
194 : */
195 : struct css_set {
196 : /*
197 : * Set of subsystem states, one for each subsystem. This array is
198 : * immutable after creation apart from the init_css_set during
199 : * subsystem registration (at boot time).
200 : */
201 : struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
202 :
203 : /* reference count */
204 : refcount_t refcount;
205 :
206 : /*
207 : * For a domain cgroup, the following points to self. If threaded,
208 : * to the matching cset of the nearest domain ancestor. The
209 : * dom_cset provides access to the domain cgroup and its csses to
210 : * which domain level resource consumptions should be charged.
211 : */
212 : struct css_set *dom_cset;
213 :
214 : /* the default cgroup associated with this css_set */
215 : struct cgroup *dfl_cgrp;
216 :
217 : /* internal task count, protected by css_set_lock */
218 : int nr_tasks;
219 :
220 : /*
221 : * Lists running through all tasks using this cgroup group.
222 : * mg_tasks lists tasks which belong to this cset but are in the
223 : * process of being migrated out or in. Protected by
224 : * css_set_rwsem, but, during migration, once tasks are moved to
225 : * mg_tasks, it can be read safely while holding cgroup_mutex.
226 : */
227 : struct list_head tasks;
228 : struct list_head mg_tasks;
229 : struct list_head dying_tasks;
230 :
231 : /* all css_task_iters currently walking this cset */
232 : struct list_head task_iters;
233 :
234 : /*
235 : * On the default hierarhcy, ->subsys[ssid] may point to a css
236 : * attached to an ancestor instead of the cgroup this css_set is
237 : * associated with. The following node is anchored at
238 : * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
239 : * iterate through all css's attached to a given cgroup.
240 : */
241 : struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
242 :
243 : /* all threaded csets whose ->dom_cset points to this cset */
244 : struct list_head threaded_csets;
245 : struct list_head threaded_csets_node;
246 :
247 : /*
248 : * List running through all cgroup groups in the same hash
249 : * slot. Protected by css_set_lock
250 : */
251 : struct hlist_node hlist;
252 :
253 : /*
254 : * List of cgrp_cset_links pointing at cgroups referenced from this
255 : * css_set. Protected by css_set_lock.
256 : */
257 : struct list_head cgrp_links;
258 :
259 : /*
260 : * List of csets participating in the on-going migration either as
261 : * source or destination. Protected by cgroup_mutex.
262 : */
263 : struct list_head mg_preload_node;
264 : struct list_head mg_node;
265 :
266 : /*
267 : * If this cset is acting as the source of migration the following
268 : * two fields are set. mg_src_cgrp and mg_dst_cgrp are
269 : * respectively the source and destination cgroups of the on-going
270 : * migration. mg_dst_cset is the destination cset the target tasks
271 : * on this cset should be migrated to. Protected by cgroup_mutex.
272 : */
273 : struct cgroup *mg_src_cgrp;
274 : struct cgroup *mg_dst_cgrp;
275 : struct css_set *mg_dst_cset;
276 :
277 : /* dead and being drained, ignore for migration */
278 : bool dead;
279 :
280 : /* For RCU-protected deletion */
281 : struct rcu_head rcu_head;
282 : };
283 :
284 : struct cgroup_base_stat {
285 : struct task_cputime cputime;
286 : };
287 :
288 : /*
289 : * rstat - cgroup scalable recursive statistics. Accounting is done
290 : * per-cpu in cgroup_rstat_cpu which is then lazily propagated up the
291 : * hierarchy on reads.
292 : *
293 : * When a stat gets updated, the cgroup_rstat_cpu and its ancestors are
294 : * linked into the updated tree. On the following read, propagation only
295 : * considers and consumes the updated tree. This makes reading O(the
296 : * number of descendants which have been active since last read) instead of
297 : * O(the total number of descendants).
298 : *
299 : * This is important because there can be a lot of (draining) cgroups which
300 : * aren't active and stat may be read frequently. The combination can
301 : * become very expensive. By propagating selectively, increasing reading
302 : * frequency decreases the cost of each read.
303 : *
304 : * This struct hosts both the fields which implement the above -
305 : * updated_children and updated_next - and the fields which track basic
306 : * resource statistics on top of it - bsync, bstat and last_bstat.
307 : */
308 : struct cgroup_rstat_cpu {
309 : /*
310 : * ->bsync protects ->bstat. These are the only fields which get
311 : * updated in the hot path.
312 : */
313 : struct u64_stats_sync bsync;
314 : struct cgroup_base_stat bstat;
315 :
316 : /*
317 : * Snapshots at the last reading. These are used to calculate the
318 : * deltas to propagate to the global counters.
319 : */
320 : struct cgroup_base_stat last_bstat;
321 :
322 : /*
323 : * Child cgroups with stat updates on this cpu since the last read
324 : * are linked on the parent's ->updated_children through
325 : * ->updated_next.
326 : *
327 : * In addition to being more compact, singly-linked list pointing
328 : * to the cgroup makes it unnecessary for each per-cpu struct to
329 : * point back to the associated cgroup.
330 : *
331 : * Protected by per-cpu cgroup_rstat_cpu_lock.
332 : */
333 : struct cgroup *updated_children; /* terminated by self cgroup */
334 : struct cgroup *updated_next; /* NULL iff not on the list */
335 : };
336 :
337 : struct cgroup_freezer_state {
338 : /* Should the cgroup and its descendants be frozen. */
339 : bool freeze;
340 :
341 : /* Should the cgroup actually be frozen? */
342 : int e_freeze;
343 :
344 : /* Fields below are protected by css_set_lock */
345 :
346 : /* Number of frozen descendant cgroups */
347 : int nr_frozen_descendants;
348 :
349 : /*
350 : * Number of tasks, which are counted as frozen:
351 : * frozen, SIGSTOPped, and PTRACEd.
352 : */
353 : int nr_frozen_tasks;
354 : };
355 :
356 : struct cgroup {
357 : /* self css with NULL ->ss, points back to this cgroup */
358 : struct cgroup_subsys_state self;
359 :
360 : unsigned long flags; /* "unsigned long" so bitops work */
361 :
362 : /*
363 : * The depth this cgroup is at. The root is at depth zero and each
364 : * step down the hierarchy increments the level. This along with
365 : * ancestor_ids[] can determine whether a given cgroup is a
366 : * descendant of another without traversing the hierarchy.
367 : */
368 : int level;
369 :
370 : /* Maximum allowed descent tree depth */
371 : int max_depth;
372 :
373 : /*
374 : * Keep track of total numbers of visible and dying descent cgroups.
375 : * Dying cgroups are cgroups which were deleted by a user,
376 : * but are still existing because someone else is holding a reference.
377 : * max_descendants is a maximum allowed number of descent cgroups.
378 : *
379 : * nr_descendants and nr_dying_descendants are protected
380 : * by cgroup_mutex and css_set_lock. It's fine to read them holding
381 : * any of cgroup_mutex and css_set_lock; for writing both locks
382 : * should be held.
383 : */
384 : int nr_descendants;
385 : int nr_dying_descendants;
386 : int max_descendants;
387 :
388 : /*
389 : * Each non-empty css_set associated with this cgroup contributes
390 : * one to nr_populated_csets. The counter is zero iff this cgroup
391 : * doesn't have any tasks.
392 : *
393 : * All children which have non-zero nr_populated_csets and/or
394 : * nr_populated_children of their own contribute one to either
395 : * nr_populated_domain_children or nr_populated_threaded_children
396 : * depending on their type. Each counter is zero iff all cgroups
397 : * of the type in the subtree proper don't have any tasks.
398 : */
399 : int nr_populated_csets;
400 : int nr_populated_domain_children;
401 : int nr_populated_threaded_children;
402 :
403 : int nr_threaded_children; /* # of live threaded child cgroups */
404 :
405 : struct kernfs_node *kn; /* cgroup kernfs entry */
406 : struct cgroup_file procs_file; /* handle for "cgroup.procs" */
407 : struct cgroup_file events_file; /* handle for "cgroup.events" */
408 :
409 : /*
410 : * The bitmask of subsystems enabled on the child cgroups.
411 : * ->subtree_control is the one configured through
412 : * "cgroup.subtree_control" while ->child_ss_mask is the effective
413 : * one which may have more subsystems enabled. Controller knobs
414 : * are made available iff it's enabled in ->subtree_control.
415 : */
416 : u16 subtree_control;
417 : u16 subtree_ss_mask;
418 : u16 old_subtree_control;
419 : u16 old_subtree_ss_mask;
420 :
421 : /* Private pointers for each registered subsystem */
422 : struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
423 :
424 : struct cgroup_root *root;
425 :
426 : /*
427 : * List of cgrp_cset_links pointing at css_sets with tasks in this
428 : * cgroup. Protected by css_set_lock.
429 : */
430 : struct list_head cset_links;
431 :
432 : /*
433 : * On the default hierarchy, a css_set for a cgroup with some
434 : * susbsys disabled will point to css's which are associated with
435 : * the closest ancestor which has the subsys enabled. The
436 : * following lists all css_sets which point to this cgroup's css
437 : * for the given subsystem.
438 : */
439 : struct list_head e_csets[CGROUP_SUBSYS_COUNT];
440 :
441 : /*
442 : * If !threaded, self. If threaded, it points to the nearest
443 : * domain ancestor. Inside a threaded subtree, cgroups are exempt
444 : * from process granularity and no-internal-task constraint.
445 : * Domain level resource consumptions which aren't tied to a
446 : * specific task are charged to the dom_cgrp.
447 : */
448 : struct cgroup *dom_cgrp;
449 : struct cgroup *old_dom_cgrp; /* used while enabling threaded */
450 :
451 : /* per-cpu recursive resource statistics */
452 : struct cgroup_rstat_cpu __percpu *rstat_cpu;
453 : struct list_head rstat_css_list;
454 :
455 : /* cgroup basic resource statistics */
456 : struct cgroup_base_stat last_bstat;
457 : struct cgroup_base_stat bstat;
458 : struct prev_cputime prev_cputime; /* for printing out cputime */
459 :
460 : /*
461 : * list of pidlists, up to two for each namespace (one for procs, one
462 : * for tasks); created on demand.
463 : */
464 : struct list_head pidlists;
465 : struct mutex pidlist_mutex;
466 :
467 : /* used to wait for offlining of csses */
468 : wait_queue_head_t offline_waitq;
469 :
470 : /* used to schedule release agent */
471 : struct work_struct release_agent_work;
472 :
473 : /* used to track pressure stalls */
474 : struct psi_group psi;
475 :
476 : /* used to store eBPF programs */
477 : struct cgroup_bpf bpf;
478 :
479 : /* If there is block congestion on this cgroup. */
480 : atomic_t congestion_count;
481 :
482 : /* Used to store internal freezer state */
483 : struct cgroup_freezer_state freezer;
484 :
485 : /* ids of the ancestors at each level including self */
486 : u64 ancestor_ids[];
487 : };
488 :
489 : /*
490 : * A cgroup_root represents the root of a cgroup hierarchy, and may be
491 : * associated with a kernfs_root to form an active hierarchy. This is
492 : * internal to cgroup core. Don't access directly from controllers.
493 : */
494 : struct cgroup_root {
495 : struct kernfs_root *kf_root;
496 :
497 : /* The bitmask of subsystems attached to this hierarchy */
498 : unsigned int subsys_mask;
499 :
500 : /* Unique id for this hierarchy. */
501 : int hierarchy_id;
502 :
503 : /* The root cgroup. Root is destroyed on its release. */
504 : struct cgroup cgrp;
505 :
506 : /* for cgrp->ancestor_ids[0] */
507 : u64 cgrp_ancestor_id_storage;
508 :
509 : /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
510 : atomic_t nr_cgrps;
511 :
512 : /* A list running through the active hierarchies */
513 : struct list_head root_list;
514 :
515 : /* Hierarchy-specific flags */
516 : unsigned int flags;
517 :
518 : /* The path to use for release notifications. */
519 : char release_agent_path[PATH_MAX];
520 :
521 : /* The name for this hierarchy - may be empty */
522 : char name[MAX_CGROUP_ROOT_NAMELEN];
523 : };
524 :
525 : /*
526 : * struct cftype: handler definitions for cgroup control files
527 : *
528 : * When reading/writing to a file:
529 : * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
530 : * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
531 : */
532 : struct cftype {
533 : /*
534 : * By convention, the name should begin with the name of the
535 : * subsystem, followed by a period. Zero length string indicates
536 : * end of cftype array.
537 : */
538 : char name[MAX_CFTYPE_NAME];
539 : unsigned long private;
540 :
541 : /*
542 : * The maximum length of string, excluding trailing nul, that can
543 : * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
544 : */
545 : size_t max_write_len;
546 :
547 : /* CFTYPE_* flags */
548 : unsigned int flags;
549 :
550 : /*
551 : * If non-zero, should contain the offset from the start of css to
552 : * a struct cgroup_file field. cgroup will record the handle of
553 : * the created file into it. The recorded handle can be used as
554 : * long as the containing css remains accessible.
555 : */
556 : unsigned int file_offset;
557 :
558 : /*
559 : * Fields used for internal bookkeeping. Initialized automatically
560 : * during registration.
561 : */
562 : struct cgroup_subsys *ss; /* NULL for cgroup core files */
563 : struct list_head node; /* anchored at ss->cfts */
564 : struct kernfs_ops *kf_ops;
565 :
566 : int (*open)(struct kernfs_open_file *of);
567 : void (*release)(struct kernfs_open_file *of);
568 :
569 : /*
570 : * read_u64() is a shortcut for the common case of returning a
571 : * single integer. Use it in place of read()
572 : */
573 : u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
574 : /*
575 : * read_s64() is a signed version of read_u64()
576 : */
577 : s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
578 :
579 : /* generic seq_file read interface */
580 : int (*seq_show)(struct seq_file *sf, void *v);
581 :
582 : /* optional ops, implement all or none */
583 : void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
584 : void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
585 : void (*seq_stop)(struct seq_file *sf, void *v);
586 :
587 : /*
588 : * write_u64() is a shortcut for the common case of accepting
589 : * a single integer (as parsed by simple_strtoull) from
590 : * userspace. Use in place of write(); return 0 or error.
591 : */
592 : int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
593 : u64 val);
594 : /*
595 : * write_s64() is a signed version of write_u64()
596 : */
597 : int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
598 : s64 val);
599 :
600 : /*
601 : * write() is the generic write callback which maps directly to
602 : * kernfs write operation and overrides all other operations.
603 : * Maximum write size is determined by ->max_write_len. Use
604 : * of_css/cft() to access the associated css and cft.
605 : */
606 : ssize_t (*write)(struct kernfs_open_file *of,
607 : char *buf, size_t nbytes, loff_t off);
608 :
609 : __poll_t (*poll)(struct kernfs_open_file *of,
610 : struct poll_table_struct *pt);
611 :
612 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
613 : struct lock_class_key lockdep_key;
614 : #endif
615 : };
616 :
617 : /*
618 : * Control Group subsystem type.
619 : * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
620 : */
621 : struct cgroup_subsys {
622 : struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
623 : int (*css_online)(struct cgroup_subsys_state *css);
624 : void (*css_offline)(struct cgroup_subsys_state *css);
625 : void (*css_released)(struct cgroup_subsys_state *css);
626 : void (*css_free)(struct cgroup_subsys_state *css);
627 : void (*css_reset)(struct cgroup_subsys_state *css);
628 : void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu);
629 : int (*css_extra_stat_show)(struct seq_file *seq,
630 : struct cgroup_subsys_state *css);
631 :
632 : int (*can_attach)(struct cgroup_taskset *tset);
633 : void (*cancel_attach)(struct cgroup_taskset *tset);
634 : void (*attach)(struct cgroup_taskset *tset);
635 : void (*post_attach)(void);
636 : int (*can_fork)(struct task_struct *task,
637 : struct css_set *cset);
638 : void (*cancel_fork)(struct task_struct *task, struct css_set *cset);
639 : void (*fork)(struct task_struct *task);
640 : void (*exit)(struct task_struct *task);
641 : void (*release)(struct task_struct *task);
642 : void (*bind)(struct cgroup_subsys_state *root_css);
643 :
644 : bool early_init:1;
645 :
646 : /*
647 : * If %true, the controller, on the default hierarchy, doesn't show
648 : * up in "cgroup.controllers" or "cgroup.subtree_control", is
649 : * implicitly enabled on all cgroups on the default hierarchy, and
650 : * bypasses the "no internal process" constraint. This is for
651 : * utility type controllers which is transparent to userland.
652 : *
653 : * An implicit controller can be stolen from the default hierarchy
654 : * anytime and thus must be okay with offline csses from previous
655 : * hierarchies coexisting with csses for the current one.
656 : */
657 : bool implicit_on_dfl:1;
658 :
659 : /*
660 : * If %true, the controller, supports threaded mode on the default
661 : * hierarchy. In a threaded subtree, both process granularity and
662 : * no-internal-process constraint are ignored and a threaded
663 : * controllers should be able to handle that.
664 : *
665 : * Note that as an implicit controller is automatically enabled on
666 : * all cgroups on the default hierarchy, it should also be
667 : * threaded. implicit && !threaded is not supported.
668 : */
669 : bool threaded:1;
670 :
671 : /* the following two fields are initialized automtically during boot */
672 : int id;
673 : const char *name;
674 :
675 : /* optional, initialized automatically during boot if not set */
676 : const char *legacy_name;
677 :
678 : /* link to parent, protected by cgroup_lock() */
679 : struct cgroup_root *root;
680 :
681 : /* idr for css->id */
682 : struct idr css_idr;
683 :
684 : /*
685 : * List of cftypes. Each entry is the first entry of an array
686 : * terminated by zero length name.
687 : */
688 : struct list_head cfts;
689 :
690 : /*
691 : * Base cftypes which are automatically registered. The two can
692 : * point to the same array.
693 : */
694 : struct cftype *dfl_cftypes; /* for the default hierarchy */
695 : struct cftype *legacy_cftypes; /* for the legacy hierarchies */
696 :
697 : /*
698 : * A subsystem may depend on other subsystems. When such subsystem
699 : * is enabled on a cgroup, the depended-upon subsystems are enabled
700 : * together if available. Subsystems enabled due to dependency are
701 : * not visible to userland until explicitly enabled. The following
702 : * specifies the mask of subsystems that this one depends on.
703 : */
704 : unsigned int depends_on;
705 : };
706 :
707 : extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
708 :
709 : /**
710 : * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
711 : * @tsk: target task
712 : *
713 : * Allows cgroup operations to synchronize against threadgroup changes
714 : * using a percpu_rw_semaphore.
715 : */
716 2020 : static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
717 : {
718 2020 : percpu_down_read(&cgroup_threadgroup_rwsem);
719 : }
720 :
721 : /**
722 : * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
723 : * @tsk: target task
724 : *
725 : * Counterpart of cgroup_threadcgroup_change_begin().
726 : */
727 2020 : static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
728 : {
729 2020 : percpu_up_read(&cgroup_threadgroup_rwsem);
730 : }
731 :
732 : #else /* CONFIG_CGROUPS */
733 :
734 : #define CGROUP_SUBSYS_COUNT 0
735 :
736 : static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
737 : {
738 : might_sleep();
739 : }
740 :
741 : static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
742 :
743 : #endif /* CONFIG_CGROUPS */
744 :
745 : #ifdef CONFIG_SOCK_CGROUP_DATA
746 :
747 : /*
748 : * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
749 : * per-socket cgroup information except for memcg association.
750 : *
751 : * On legacy hierarchies, net_prio and net_cls controllers directly set
752 : * attributes on each sock which can then be tested by the network layer.
753 : * On the default hierarchy, each sock is associated with the cgroup it was
754 : * created in and the networking layer can match the cgroup directly.
755 : *
756 : * To avoid carrying all three cgroup related fields separately in sock,
757 : * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer.
758 : * On boot, sock_cgroup_data records the cgroup that the sock was created
759 : * in so that cgroup2 matches can be made; however, once either net_prio or
760 : * net_cls starts being used, the area is overriden to carry prioidx and/or
761 : * classid. The two modes are distinguished by whether the lowest bit is
762 : * set. Clear bit indicates cgroup pointer while set bit prioidx and
763 : * classid.
764 : *
765 : * While userland may start using net_prio or net_cls at any time, once
766 : * either is used, cgroup2 matching no longer works. There is no reason to
767 : * mix the two and this is in line with how legacy and v2 compatibility is
768 : * handled. On mode switch, cgroup references which are already being
769 : * pointed to by socks may be leaked. While this can be remedied by adding
770 : * synchronization around sock_cgroup_data, given that the number of leaked
771 : * cgroups is bound and highly unlikely to be high, this seems to be the
772 : * better trade-off.
773 : */
774 : struct sock_cgroup_data {
775 : union {
776 : #ifdef __LITTLE_ENDIAN
777 : struct {
778 : u8 is_data : 1;
779 : u8 no_refcnt : 1;
780 : u8 unused : 6;
781 : u8 padding;
782 : u16 prioidx;
783 : u32 classid;
784 : } __packed;
785 : #else
786 : struct {
787 : u32 classid;
788 : u16 prioidx;
789 : u8 padding;
790 : u8 unused : 6;
791 : u8 no_refcnt : 1;
792 : u8 is_data : 1;
793 : } __packed;
794 : #endif
795 : u64 val;
796 : };
797 : };
798 :
799 : /*
800 : * There's a theoretical window where the following accessors race with
801 : * updaters and return part of the previous pointer as the prioidx or
802 : * classid. Such races are short-lived and the result isn't critical.
803 : */
804 : static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
805 : {
806 : /* fallback to 1 which is always the ID of the root cgroup */
807 : return (skcd->is_data & 1) ? skcd->prioidx : 1;
808 : }
809 :
810 : static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
811 : {
812 : /* fallback to 0 which is the unconfigured default classid */
813 : return (skcd->is_data & 1) ? skcd->classid : 0;
814 : }
815 :
816 : /*
817 : * If invoked concurrently, the updaters may clobber each other. The
818 : * caller is responsible for synchronization.
819 : */
820 : static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
821 : u16 prioidx)
822 : {
823 : struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
824 :
825 : if (sock_cgroup_prioidx(&skcd_buf) == prioidx)
826 : return;
827 :
828 : if (!(skcd_buf.is_data & 1)) {
829 : skcd_buf.val = 0;
830 : skcd_buf.is_data = 1;
831 : }
832 :
833 : skcd_buf.prioidx = prioidx;
834 : WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */
835 : }
836 :
837 : static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
838 : u32 classid)
839 : {
840 : struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
841 :
842 : if (sock_cgroup_classid(&skcd_buf) == classid)
843 : return;
844 :
845 : if (!(skcd_buf.is_data & 1)) {
846 : skcd_buf.val = 0;
847 : skcd_buf.is_data = 1;
848 : }
849 :
850 : skcd_buf.classid = classid;
851 : WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */
852 : }
853 :
854 : #else /* CONFIG_SOCK_CGROUP_DATA */
855 :
856 : struct sock_cgroup_data {
857 : };
858 :
859 : #endif /* CONFIG_SOCK_CGROUP_DATA */
860 :
861 : #endif /* _LINUX_CGROUP_DEFS_H */
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