include/linux/cgroup-defs.h

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