1 /* SPDX-License-Identifier: GPL-2.0 */
3 * linux/cgroup-defs.h - basic definitions for cgroup
5 * This file provides basic type and interface. Include this file directly
6 * only if necessary to avoid cyclic dependencies.
8 #ifndef _LINUX_CGROUP_DEFS_H
9 #define _LINUX_CGROUP_DEFS_H
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/workqueue.h>
21 #include <linux/bpf-cgroup.h>
28 struct cgroup_taskset
;
31 struct kernfs_open_file
;
34 #define MAX_CGROUP_TYPE_NAMELEN 32
35 #define MAX_CGROUP_ROOT_NAMELEN 64
36 #define MAX_CFTYPE_NAME 64
38 /* define the enumeration of all cgroup subsystems */
39 #define SUBSYS(_x) _x ## _cgrp_id,
40 enum cgroup_subsys_id
{
41 #include <linux/cgroup_subsys.h>
46 /* bits in struct cgroup_subsys_state flags field */
48 CSS_NO_REF
= (1 << 0), /* no reference counting for this css */
49 CSS_ONLINE
= (1 << 1), /* between ->css_online() and ->css_offline() */
50 CSS_RELEASED
= (1 << 2), /* refcnt reached zero, released */
51 CSS_VISIBLE
= (1 << 3), /* css is visible to userland */
52 CSS_DYING
= (1 << 4), /* css is dying */
55 /* bits in struct cgroup flags field */
57 /* Control Group requires release notifications to userspace */
58 CGRP_NOTIFY_ON_RELEASE
,
60 * Clone the parent's configuration when creating a new child
61 * cpuset cgroup. For historical reasons, this option can be
62 * specified at mount time and thus is implemented here.
64 CGRP_CPUSET_CLONE_CHILDREN
,
67 /* cgroup_root->flags */
69 CGRP_ROOT_NOPREFIX
= (1 << 1), /* mounted subsystems have no named prefix */
70 CGRP_ROOT_XATTR
= (1 << 2), /* supports extended attributes */
73 * Consider namespaces as delegation boundaries. If this flag is
74 * set, controller specific interface files in a namespace root
75 * aren't writeable from inside the namespace.
77 CGRP_ROOT_NS_DELEGATE
= (1 << 3),
80 * Enable cpuset controller in v1 cgroup to use v2 behavior.
82 CGRP_ROOT_CPUSET_V2_MODE
= (1 << 4),
87 CFTYPE_ONLY_ON_ROOT
= (1 << 0), /* only create on root cgrp */
88 CFTYPE_NOT_ON_ROOT
= (1 << 1), /* don't create on root cgrp */
89 CFTYPE_NS_DELEGATABLE
= (1 << 2), /* writeable beyond delegation boundaries */
91 CFTYPE_NO_PREFIX
= (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
92 CFTYPE_WORLD_WRITABLE
= (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
94 /* internal flags, do not use outside cgroup core proper */
95 __CFTYPE_ONLY_ON_DFL
= (1 << 16), /* only on default hierarchy */
96 __CFTYPE_NOT_ON_DFL
= (1 << 17), /* not on default hierarchy */
100 * cgroup_file is the handle for a file instance created in a cgroup which
101 * is used, for example, to generate file changed notifications. This can
102 * be obtained by setting cftype->file_offset.
105 /* do not access any fields from outside cgroup core */
106 struct kernfs_node
*kn
;
110 * Per-subsystem/per-cgroup state maintained by the system. This is the
111 * fundamental structural building block that controllers deal with.
113 * Fields marked with "PI:" are public and immutable and may be accessed
114 * directly without synchronization.
116 struct cgroup_subsys_state
{
117 /* PI: the cgroup that this css is attached to */
118 struct cgroup
*cgroup
;
120 /* PI: the cgroup subsystem that this css is attached to */
121 struct cgroup_subsys
*ss
;
123 /* reference count - access via css_[try]get() and css_put() */
124 struct percpu_ref refcnt
;
126 /* siblings list anchored at the parent's ->children */
127 struct list_head sibling
;
128 struct list_head children
;
131 * PI: Subsys-unique ID. 0 is unused and root is always 1. The
132 * matching css can be looked up using css_from_id().
139 * Monotonically increasing unique serial number which defines a
140 * uniform order among all csses. It's guaranteed that all
141 * ->children lists are in the ascending order of ->serial_nr and
142 * used to allow interrupting and resuming iterations.
147 * Incremented by online self and children. Used to guarantee that
148 * parents are not offlined before their children.
152 /* percpu_ref killing and RCU release */
153 struct rcu_head rcu_head
;
154 struct work_struct destroy_work
;
157 * PI: the parent css. Placed here for cache proximity to following
158 * fields of the containing structure.
160 struct cgroup_subsys_state
*parent
;
164 * A css_set is a structure holding pointers to a set of
165 * cgroup_subsys_state objects. This saves space in the task struct
166 * object and speeds up fork()/exit(), since a single inc/dec and a
167 * list_add()/del() can bump the reference count on the entire cgroup
172 * Set of subsystem states, one for each subsystem. This array is
173 * immutable after creation apart from the init_css_set during
174 * subsystem registration (at boot time).
176 struct cgroup_subsys_state
*subsys
[CGROUP_SUBSYS_COUNT
];
178 /* reference count */
182 * For a domain cgroup, the following points to self. If threaded,
183 * to the matching cset of the nearest domain ancestor. The
184 * dom_cset provides access to the domain cgroup and its csses to
185 * which domain level resource consumptions should be charged.
187 struct css_set
*dom_cset
;
189 /* the default cgroup associated with this css_set */
190 struct cgroup
*dfl_cgrp
;
192 /* internal task count, protected by css_set_lock */
196 * Lists running through all tasks using this cgroup group.
197 * mg_tasks lists tasks which belong to this cset but are in the
198 * process of being migrated out or in. Protected by
199 * css_set_rwsem, but, during migration, once tasks are moved to
200 * mg_tasks, it can be read safely while holding cgroup_mutex.
202 struct list_head tasks
;
203 struct list_head mg_tasks
;
205 /* all css_task_iters currently walking this cset */
206 struct list_head task_iters
;
209 * On the default hierarhcy, ->subsys[ssid] may point to a css
210 * attached to an ancestor instead of the cgroup this css_set is
211 * associated with. The following node is anchored at
212 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
213 * iterate through all css's attached to a given cgroup.
215 struct list_head e_cset_node
[CGROUP_SUBSYS_COUNT
];
217 /* all threaded csets whose ->dom_cset points to this cset */
218 struct list_head threaded_csets
;
219 struct list_head threaded_csets_node
;
222 * List running through all cgroup groups in the same hash
223 * slot. Protected by css_set_lock
225 struct hlist_node hlist
;
228 * List of cgrp_cset_links pointing at cgroups referenced from this
229 * css_set. Protected by css_set_lock.
231 struct list_head cgrp_links
;
234 * List of csets participating in the on-going migration either as
235 * source or destination. Protected by cgroup_mutex.
237 struct list_head mg_preload_node
;
238 struct list_head mg_node
;
241 * If this cset is acting as the source of migration the following
242 * two fields are set. mg_src_cgrp and mg_dst_cgrp are
243 * respectively the source and destination cgroups of the on-going
244 * migration. mg_dst_cset is the destination cset the target tasks
245 * on this cset should be migrated to. Protected by cgroup_mutex.
247 struct cgroup
*mg_src_cgrp
;
248 struct cgroup
*mg_dst_cgrp
;
249 struct css_set
*mg_dst_cset
;
251 /* dead and being drained, ignore for migration */
254 /* For RCU-protected deletion */
255 struct rcu_head rcu_head
;
259 /* self css with NULL ->ss, points back to this cgroup */
260 struct cgroup_subsys_state self
;
262 unsigned long flags
; /* "unsigned long" so bitops work */
265 * idr allocated in-hierarchy ID.
267 * ID 0 is not used, the ID of the root cgroup is always 1, and a
268 * new cgroup will be assigned with a smallest available ID.
270 * Allocating/Removing ID must be protected by cgroup_mutex.
275 * The depth this cgroup is at. The root is at depth zero and each
276 * step down the hierarchy increments the level. This along with
277 * ancestor_ids[] can determine whether a given cgroup is a
278 * descendant of another without traversing the hierarchy.
282 /* Maximum allowed descent tree depth */
286 * Keep track of total numbers of visible and dying descent cgroups.
287 * Dying cgroups are cgroups which were deleted by a user,
288 * but are still existing because someone else is holding a reference.
289 * max_descendants is a maximum allowed number of descent cgroups.
292 int nr_dying_descendants
;
296 * Each non-empty css_set associated with this cgroup contributes
297 * one to nr_populated_csets. The counter is zero iff this cgroup
298 * doesn't have any tasks.
300 * All children which have non-zero nr_populated_csets and/or
301 * nr_populated_children of their own contribute one to either
302 * nr_populated_domain_children or nr_populated_threaded_children
303 * depending on their type. Each counter is zero iff all cgroups
304 * of the type in the subtree proper don't have any tasks.
306 int nr_populated_csets
;
307 int nr_populated_domain_children
;
308 int nr_populated_threaded_children
;
310 int nr_threaded_children
; /* # of live threaded child cgroups */
312 struct kernfs_node
*kn
; /* cgroup kernfs entry */
313 struct cgroup_file procs_file
; /* handle for "cgroup.procs" */
314 struct cgroup_file events_file
; /* handle for "cgroup.events" */
317 * The bitmask of subsystems enabled on the child cgroups.
318 * ->subtree_control is the one configured through
319 * "cgroup.subtree_control" while ->child_ss_mask is the effective
320 * one which may have more subsystems enabled. Controller knobs
321 * are made available iff it's enabled in ->subtree_control.
325 u16 old_subtree_control
;
326 u16 old_subtree_ss_mask
;
328 /* Private pointers for each registered subsystem */
329 struct cgroup_subsys_state __rcu
*subsys
[CGROUP_SUBSYS_COUNT
];
331 struct cgroup_root
*root
;
334 * List of cgrp_cset_links pointing at css_sets with tasks in this
335 * cgroup. Protected by css_set_lock.
337 struct list_head cset_links
;
340 * On the default hierarchy, a css_set for a cgroup with some
341 * susbsys disabled will point to css's which are associated with
342 * the closest ancestor which has the subsys enabled. The
343 * following lists all css_sets which point to this cgroup's css
344 * for the given subsystem.
346 struct list_head e_csets
[CGROUP_SUBSYS_COUNT
];
349 * If !threaded, self. If threaded, it points to the nearest
350 * domain ancestor. Inside a threaded subtree, cgroups are exempt
351 * from process granularity and no-internal-task constraint.
352 * Domain level resource consumptions which aren't tied to a
353 * specific task are charged to the dom_cgrp.
355 struct cgroup
*dom_cgrp
;
358 * list of pidlists, up to two for each namespace (one for procs, one
359 * for tasks); created on demand.
361 struct list_head pidlists
;
362 struct mutex pidlist_mutex
;
364 /* used to wait for offlining of csses */
365 wait_queue_head_t offline_waitq
;
367 /* used to schedule release agent */
368 struct work_struct release_agent_work
;
370 /* used to store eBPF programs */
371 struct cgroup_bpf bpf
;
373 /* ids of the ancestors at each level including self */
378 * A cgroup_root represents the root of a cgroup hierarchy, and may be
379 * associated with a kernfs_root to form an active hierarchy. This is
380 * internal to cgroup core. Don't access directly from controllers.
383 struct kernfs_root
*kf_root
;
385 /* The bitmask of subsystems attached to this hierarchy */
386 unsigned int subsys_mask
;
388 /* Unique id for this hierarchy. */
391 /* The root cgroup. Root is destroyed on its release. */
394 /* for cgrp->ancestor_ids[0] */
395 int cgrp_ancestor_id_storage
;
397 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
400 /* A list running through the active hierarchies */
401 struct list_head root_list
;
403 /* Hierarchy-specific flags */
406 /* IDs for cgroups in this hierarchy */
407 struct idr cgroup_idr
;
409 /* The path to use for release notifications. */
410 char release_agent_path
[PATH_MAX
];
412 /* The name for this hierarchy - may be empty */
413 char name
[MAX_CGROUP_ROOT_NAMELEN
];
417 * struct cftype: handler definitions for cgroup control files
419 * When reading/writing to a file:
420 * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
421 * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
425 * By convention, the name should begin with the name of the
426 * subsystem, followed by a period. Zero length string indicates
427 * end of cftype array.
429 char name
[MAX_CFTYPE_NAME
];
430 unsigned long private;
433 * The maximum length of string, excluding trailing nul, that can
434 * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
436 size_t max_write_len
;
442 * If non-zero, should contain the offset from the start of css to
443 * a struct cgroup_file field. cgroup will record the handle of
444 * the created file into it. The recorded handle can be used as
445 * long as the containing css remains accessible.
447 unsigned int file_offset
;
450 * Fields used for internal bookkeeping. Initialized automatically
451 * during registration.
453 struct cgroup_subsys
*ss
; /* NULL for cgroup core files */
454 struct list_head node
; /* anchored at ss->cfts */
455 struct kernfs_ops
*kf_ops
;
457 int (*open
)(struct kernfs_open_file
*of
);
458 void (*release
)(struct kernfs_open_file
*of
);
461 * read_u64() is a shortcut for the common case of returning a
462 * single integer. Use it in place of read()
464 u64 (*read_u64
)(struct cgroup_subsys_state
*css
, struct cftype
*cft
);
466 * read_s64() is a signed version of read_u64()
468 s64 (*read_s64
)(struct cgroup_subsys_state
*css
, struct cftype
*cft
);
470 /* generic seq_file read interface */
471 int (*seq_show
)(struct seq_file
*sf
, void *v
);
473 /* optional ops, implement all or none */
474 void *(*seq_start
)(struct seq_file
*sf
, loff_t
*ppos
);
475 void *(*seq_next
)(struct seq_file
*sf
, void *v
, loff_t
*ppos
);
476 void (*seq_stop
)(struct seq_file
*sf
, void *v
);
479 * write_u64() is a shortcut for the common case of accepting
480 * a single integer (as parsed by simple_strtoull) from
481 * userspace. Use in place of write(); return 0 or error.
483 int (*write_u64
)(struct cgroup_subsys_state
*css
, struct cftype
*cft
,
486 * write_s64() is a signed version of write_u64()
488 int (*write_s64
)(struct cgroup_subsys_state
*css
, struct cftype
*cft
,
492 * write() is the generic write callback which maps directly to
493 * kernfs write operation and overrides all other operations.
494 * Maximum write size is determined by ->max_write_len. Use
495 * of_css/cft() to access the associated css and cft.
497 ssize_t (*write
)(struct kernfs_open_file
*of
,
498 char *buf
, size_t nbytes
, loff_t off
);
500 #ifdef CONFIG_DEBUG_LOCK_ALLOC
501 struct lock_class_key lockdep_key
;
506 * Control Group subsystem type.
507 * See Documentation/cgroups/cgroups.txt for details
509 struct cgroup_subsys
{
510 struct cgroup_subsys_state
*(*css_alloc
)(struct cgroup_subsys_state
*parent_css
);
511 int (*css_online
)(struct cgroup_subsys_state
*css
);
512 void (*css_offline
)(struct cgroup_subsys_state
*css
);
513 void (*css_released
)(struct cgroup_subsys_state
*css
);
514 void (*css_free
)(struct cgroup_subsys_state
*css
);
515 void (*css_reset
)(struct cgroup_subsys_state
*css
);
517 int (*can_attach
)(struct cgroup_taskset
*tset
);
518 void (*cancel_attach
)(struct cgroup_taskset
*tset
);
519 void (*attach
)(struct cgroup_taskset
*tset
);
520 void (*post_attach
)(void);
521 int (*can_fork
)(struct task_struct
*task
);
522 void (*cancel_fork
)(struct task_struct
*task
);
523 void (*fork
)(struct task_struct
*task
);
524 void (*exit
)(struct task_struct
*task
);
525 void (*free
)(struct task_struct
*task
);
526 void (*bind
)(struct cgroup_subsys_state
*root_css
);
531 * If %true, the controller, on the default hierarchy, doesn't show
532 * up in "cgroup.controllers" or "cgroup.subtree_control", is
533 * implicitly enabled on all cgroups on the default hierarchy, and
534 * bypasses the "no internal process" constraint. This is for
535 * utility type controllers which is transparent to userland.
537 * An implicit controller can be stolen from the default hierarchy
538 * anytime and thus must be okay with offline csses from previous
539 * hierarchies coexisting with csses for the current one.
541 bool implicit_on_dfl
:1;
544 * If %true, the controller, supports threaded mode on the default
545 * hierarchy. In a threaded subtree, both process granularity and
546 * no-internal-process constraint are ignored and a threaded
547 * controllers should be able to handle that.
549 * Note that as an implicit controller is automatically enabled on
550 * all cgroups on the default hierarchy, it should also be
551 * threaded. implicit && !threaded is not supported.
556 * If %false, this subsystem is properly hierarchical -
557 * configuration, resource accounting and restriction on a parent
558 * cgroup cover those of its children. If %true, hierarchy support
559 * is broken in some ways - some subsystems ignore hierarchy
560 * completely while others are only implemented half-way.
562 * It's now disallowed to create nested cgroups if the subsystem is
563 * broken and cgroup core will emit a warning message on such
564 * cases. Eventually, all subsystems will be made properly
565 * hierarchical and this will go away.
567 bool broken_hierarchy
:1;
568 bool warned_broken_hierarchy
:1;
570 /* the following two fields are initialized automtically during boot */
574 /* optional, initialized automatically during boot if not set */
575 const char *legacy_name
;
577 /* link to parent, protected by cgroup_lock() */
578 struct cgroup_root
*root
;
580 /* idr for css->id */
584 * List of cftypes. Each entry is the first entry of an array
585 * terminated by zero length name.
587 struct list_head cfts
;
590 * Base cftypes which are automatically registered. The two can
591 * point to the same array.
593 struct cftype
*dfl_cftypes
; /* for the default hierarchy */
594 struct cftype
*legacy_cftypes
; /* for the legacy hierarchies */
597 * A subsystem may depend on other subsystems. When such subsystem
598 * is enabled on a cgroup, the depended-upon subsystems are enabled
599 * together if available. Subsystems enabled due to dependency are
600 * not visible to userland until explicitly enabled. The following
601 * specifies the mask of subsystems that this one depends on.
603 unsigned int depends_on
;
606 extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem
;
609 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
612 * Allows cgroup operations to synchronize against threadgroup changes
613 * using a percpu_rw_semaphore.
615 static inline void cgroup_threadgroup_change_begin(struct task_struct
*tsk
)
617 percpu_down_read(&cgroup_threadgroup_rwsem
);
621 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
624 * Counterpart of cgroup_threadcgroup_change_begin().
626 static inline void cgroup_threadgroup_change_end(struct task_struct
*tsk
)
628 percpu_up_read(&cgroup_threadgroup_rwsem
);
631 #else /* CONFIG_CGROUPS */
633 #define CGROUP_SUBSYS_COUNT 0
635 static inline void cgroup_threadgroup_change_begin(struct task_struct
*tsk
)
640 static inline void cgroup_threadgroup_change_end(struct task_struct
*tsk
) {}
642 #endif /* CONFIG_CGROUPS */
644 #ifdef CONFIG_SOCK_CGROUP_DATA
647 * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
648 * per-socket cgroup information except for memcg association.
650 * On legacy hierarchies, net_prio and net_cls controllers directly set
651 * attributes on each sock which can then be tested by the network layer.
652 * On the default hierarchy, each sock is associated with the cgroup it was
653 * created in and the networking layer can match the cgroup directly.
655 * To avoid carrying all three cgroup related fields separately in sock,
656 * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer.
657 * On boot, sock_cgroup_data records the cgroup that the sock was created
658 * in so that cgroup2 matches can be made; however, once either net_prio or
659 * net_cls starts being used, the area is overriden to carry prioidx and/or
660 * classid. The two modes are distinguished by whether the lowest bit is
661 * set. Clear bit indicates cgroup pointer while set bit prioidx and
664 * While userland may start using net_prio or net_cls at any time, once
665 * either is used, cgroup2 matching no longer works. There is no reason to
666 * mix the two and this is in line with how legacy and v2 compatibility is
667 * handled. On mode switch, cgroup references which are already being
668 * pointed to by socks may be leaked. While this can be remedied by adding
669 * synchronization around sock_cgroup_data, given that the number of leaked
670 * cgroups is bound and highly unlikely to be high, this seems to be the
673 struct sock_cgroup_data
{
675 #ifdef __LITTLE_ENDIAN
695 * There's a theoretical window where the following accessors race with
696 * updaters and return part of the previous pointer as the prioidx or
697 * classid. Such races are short-lived and the result isn't critical.
699 static inline u16
sock_cgroup_prioidx(struct sock_cgroup_data
*skcd
)
701 /* fallback to 1 which is always the ID of the root cgroup */
702 return (skcd
->is_data
& 1) ? skcd
->prioidx
: 1;
705 static inline u32
sock_cgroup_classid(struct sock_cgroup_data
*skcd
)
707 /* fallback to 0 which is the unconfigured default classid */
708 return (skcd
->is_data
& 1) ? skcd
->classid
: 0;
712 * If invoked concurrently, the updaters may clobber each other. The
713 * caller is responsible for synchronization.
715 static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data
*skcd
,
718 struct sock_cgroup_data skcd_buf
= {{ .val
= READ_ONCE(skcd
->val
) }};
720 if (sock_cgroup_prioidx(&skcd_buf
) == prioidx
)
723 if (!(skcd_buf
.is_data
& 1)) {
725 skcd_buf
.is_data
= 1;
728 skcd_buf
.prioidx
= prioidx
;
729 WRITE_ONCE(skcd
->val
, skcd_buf
.val
); /* see sock_cgroup_ptr() */
732 static inline void sock_cgroup_set_classid(struct sock_cgroup_data
*skcd
,
735 struct sock_cgroup_data skcd_buf
= {{ .val
= READ_ONCE(skcd
->val
) }};
737 if (sock_cgroup_classid(&skcd_buf
) == classid
)
740 if (!(skcd_buf
.is_data
& 1)) {
742 skcd_buf
.is_data
= 1;
745 skcd_buf
.classid
= classid
;
746 WRITE_ONCE(skcd
->val
, skcd_buf
.val
); /* see sock_cgroup_ptr() */
749 #else /* CONFIG_SOCK_CGROUP_DATA */
751 struct sock_cgroup_data
{
754 #endif /* CONFIG_SOCK_CGROUP_DATA */
756 #endif /* _LINUX_CGROUP_DEFS_H */