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-defs.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          * Reduce latencies on dynamic cgroup modifications such as task
  93          * migrations and controller on/offs by disabling percpu operation on
  94          * cgroup_threadgroup_rwsem. This makes hot path operations such as
  95          * forks and exits into the slow path and more expensive.
  96          *
  97          * The static usage pattern of creating a cgroup, enabling controllers,
  98          * and then seeding it with CLONE_INTO_CGROUP doesn't require write
  99          * locking cgroup_threadgroup_rwsem and thus doesn't benefit from
 100          * favordynmod.
 101          */
 102         CGRP_ROOT_FAVOR_DYNMODS = (1 << 4),
 103
 104         /*
 105          * Enable cpuset controller in v1 cgroup to use v2 behavior.
 106          */
 107         CGRP_ROOT_CPUSET_V2_MODE = (1 << 16),
 108
 109         /*
 110          * Enable legacy local memory.events.
 111          */
 112         CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 17),
 113
 114         /*
 115          * Enable recursive subtree protection
 116          */
 117         CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 18),
 118 };
 119
 120 /* cftype->flags */
 121 enum {
 122         CFTYPE_ONLY_ON_ROOT     = (1 << 0),     /* only create on root cgrp */
 123         CFTYPE_NOT_ON_ROOT      = (1 << 1),     /* don't create on root cgrp */
 124         CFTYPE_NS_DELEGATABLE   = (1 << 2),     /* writeable beyond delegation boundaries */
 125
 126         CFTYPE_NO_PREFIX        = (1 << 3),     /* (DON'T USE FOR NEW FILES) no subsys prefix */
 127         CFTYPE_WORLD_WRITABLE   = (1 << 4),     /* (DON'T USE FOR NEW FILES) S_IWUGO */
 128         CFTYPE_DEBUG            = (1 << 5),     /* create when cgroup_debug */
 129
 130         /* internal flags, do not use outside cgroup core proper */
 131         __CFTYPE_ONLY_ON_DFL    = (1 << 16),    /* only on default hierarchy */
 132         __CFTYPE_NOT_ON_DFL     = (1 << 17),    /* not on default hierarchy */
 133         __CFTYPE_ADDED          = (1 << 18),
 134 };
 135
 136 /*
 137  * cgroup_file is the handle for a file instance created in a cgroup which
 138  * is used, for example, to generate file changed notifications.  This can
 139  * be obtained by setting cftype->file_offset.
 140  */
 141 struct cgroup_file {
 142         /* do not access any fields from outside cgroup core */
 143         struct kernfs_node *kn;
 144         unsigned long notified_at;
 145         struct timer_list notify_timer;
 146 };
 147
 148 /*
 149  * Per-subsystem/per-cgroup state maintained by the system.  This is the
 150  * fundamental structural building block that controllers deal with.
 151  *
 152  * Fields marked with "PI:" are public and immutable and may be accessed
 153  * directly without synchronization.
 154  */
 155 struct cgroup_subsys_state {
 156         /* PI: the cgroup that this css is attached to */
 157         struct cgroup *cgroup;
 158
 159         /* PI: the cgroup subsystem that this css is attached to */
 160         struct cgroup_subsys *ss;
 161
 162         /* reference count - access via css_[try]get() and css_put() */
 163         struct percpu_ref refcnt;
 164
 165         /* siblings list anchored at the parent's ->children */
 166         struct list_head sibling;
 167         struct list_head children;
 168
 169         /* flush target list anchored at cgrp->rstat_css_list */
 170         struct list_head rstat_css_node;
 171
 172         /*
 173          * PI: Subsys-unique ID.  0 is unused and root is always 1.  The
 174          * matching css can be looked up using css_from_id().
 175          */
 176         int id;
 177
 178         unsigned int flags;
 179
 180         /*
 181          * Monotonically increasing unique serial number which defines a
 182          * uniform order among all csses.  It's guaranteed that all
 183          * ->children lists are in the ascending order of ->serial_nr and
 184          * used to allow interrupting and resuming iterations.
 185          */
 186         u64 serial_nr;
 187
 188         /*
 189          * Incremented by online self and children.  Used to guarantee that
 190          * parents are not offlined before their children.
 191          */
 192         atomic_t online_cnt;
 193
 194         /* percpu_ref killing and RCU release */
 195         struct work_struct destroy_work;
 196         struct rcu_work destroy_rwork;
 197
 198         /*
 199          * PI: the parent css.  Placed here for cache proximity to following
 200          * fields of the containing structure.
 201          */
 202         struct cgroup_subsys_state *parent;
 203 };
 204
 205 /*
 206  * A css_set is a structure holding pointers to a set of
 207  * cgroup_subsys_state objects. This saves space in the task struct
 208  * object and speeds up fork()/exit(), since a single inc/dec and a
 209  * list_add()/del() can bump the reference count on the entire cgroup
 210  * set for a task.
 211  */
 212 struct css_set {
 213         /*
 214          * Set of subsystem states, one for each subsystem. This array is
 215          * immutable after creation apart from the init_css_set during
 216          * subsystem registration (at boot time).
 217          */
 218         struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
 219
 220         /* reference count */
 221         refcount_t refcount;
 222
 223         /*
 224          * For a domain cgroup, the following points to self.  If threaded,
 225          * to the matching cset of the nearest domain ancestor.  The
 226          * dom_cset provides access to the domain cgroup and its csses to
 227          * which domain level resource consumptions should be charged.
 228          */
 229         struct css_set *dom_cset;
 230
 231         /* the default cgroup associated with this css_set */
 232         struct cgroup *dfl_cgrp;
 233
 234         /* internal task count, protected by css_set_lock */
 235         int nr_tasks;
 236
 237         /*
 238          * Lists running through all tasks using this cgroup group.
 239          * mg_tasks lists tasks which belong to this cset but are in the
 240          * process of being migrated out or in.  Protected by
 241          * css_set_lock, but, during migration, once tasks are moved to
 242          * mg_tasks, it can be read safely while holding cgroup_mutex.
 243          */
 244         struct list_head tasks;
 245         struct list_head mg_tasks;
 246         struct list_head dying_tasks;
 247
 248         /* all css_task_iters currently walking this cset */
 249         struct list_head task_iters;
 250
 251         /*
 252          * On the default hierarchy, ->subsys[ssid] may point to a css
 253          * attached to an ancestor instead of the cgroup this css_set is
 254          * associated with.  The following node is anchored at
 255          * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
 256          * iterate through all css's attached to a given cgroup.
 257          */
 258         struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
 259
 260         /* all threaded csets whose ->dom_cset points to this cset */
 261         struct list_head threaded_csets;
 262         struct list_head threaded_csets_node;
 263
 264         /*
 265          * List running through all cgroup groups in the same hash
 266          * slot. Protected by css_set_lock
 267          */
 268         struct hlist_node hlist;
 269
 270         /*
 271          * List of cgrp_cset_links pointing at cgroups referenced from this
 272          * css_set.  Protected by css_set_lock.
 273          */
 274         struct list_head cgrp_links;
 275
 276         /*
 277          * List of csets participating in the on-going migration either as
 278          * source or destination.  Protected by cgroup_mutex.
 279          */
 280         struct list_head mg_src_preload_node;
 281         struct list_head mg_dst_preload_node;
 282         struct list_head mg_node;
 283
 284         /*
 285          * If this cset is acting as the source of migration the following
 286          * two fields are set.  mg_src_cgrp and mg_dst_cgrp are
 287          * respectively the source and destination cgroups of the on-going
 288          * migration.  mg_dst_cset is the destination cset the target tasks
 289          * on this cset should be migrated to.  Protected by cgroup_mutex.
 290          */
 291         struct cgroup *mg_src_cgrp;
 292         struct cgroup *mg_dst_cgrp;
 293         struct css_set *mg_dst_cset;
 294
 295         /* dead and being drained, ignore for migration */
 296         bool dead;
 297
 298         /* For RCU-protected deletion */
 299         struct rcu_head rcu_head;
 300 };
 301
 302 struct cgroup_base_stat {
 303         struct task_cputime cputime;
 304
 305 #ifdef CONFIG_SCHED_CORE
 306         u64 forceidle_sum;
 307 #endif
 308 };
 309
 310 /*
 311  * rstat - cgroup scalable recursive statistics.  Accounting is done
 312  * per-cpu in cgroup_rstat_cpu which is then lazily propagated up the
 313  * hierarchy on reads.
 314  *
 315  * When a stat gets updated, the cgroup_rstat_cpu and its ancestors are
 316  * linked into the updated tree.  On the following read, propagation only
 317  * considers and consumes the updated tree.  This makes reading O(the
 318  * number of descendants which have been active since last read) instead of
 319  * O(the total number of descendants).
 320  *
 321  * This is important because there can be a lot of (draining) cgroups which
 322  * aren't active and stat may be read frequently.  The combination can
 323  * become very expensive.  By propagating selectively, increasing reading
 324  * frequency decreases the cost of each read.
 325  *
 326  * This struct hosts both the fields which implement the above -
 327  * updated_children and updated_next - and the fields which track basic
 328  * resource statistics on top of it - bsync, bstat and last_bstat.
 329  */
 330 struct cgroup_rstat_cpu {
 331         /*
 332          * ->bsync protects ->bstat.  These are the only fields which get
 333          * updated in the hot path.
 334          */
 335         struct u64_stats_sync bsync;
 336         struct cgroup_base_stat bstat;
 337
 338         /*
 339          * Snapshots at the last reading.  These are used to calculate the
 340          * deltas to propagate to the global counters.
 341          */
 342         struct cgroup_base_stat last_bstat;
 343
 344         /*
 345          * This field is used to record the cumulative per-cpu time of
 346          * the cgroup and its descendants. Currently it can be read via
 347          * eBPF/drgn etc, and we are still trying to determine how to
 348          * expose it in the cgroupfs interface.
 349          */
 350         struct cgroup_base_stat subtree_bstat;
 351
 352         /*
 353          * Snapshots at the last reading. These are used to calculate the
 354          * deltas to propagate to the per-cpu subtree_bstat.
 355          */
 356         struct cgroup_base_stat last_subtree_bstat;
 357
 358         /*
 359          * Child cgroups with stat updates on this cpu since the last read
 360          * are linked on the parent's ->updated_children through
 361          * ->updated_next.
 362          *
 363          * In addition to being more compact, singly-linked list pointing
 364          * to the cgroup makes it unnecessary for each per-cpu struct to
 365          * point back to the associated cgroup.
 366          *
 367          * Protected by per-cpu cgroup_rstat_cpu_lock.
 368          */
 369         struct cgroup *updated_children;        /* terminated by self cgroup */
 370         struct cgroup *updated_next;            /* NULL iff not on the list */
 371 };
 372
 373 struct cgroup_freezer_state {
 374         /* Should the cgroup and its descendants be frozen. */
 375         bool freeze;
 376
 377         /* Should the cgroup actually be frozen? */
 378         int e_freeze;
 379
 380         /* Fields below are protected by css_set_lock */
 381
 382         /* Number of frozen descendant cgroups */
 383         int nr_frozen_descendants;
 384
 385         /*
 386          * Number of tasks, which are counted as frozen:
 387          * frozen, SIGSTOPped, and PTRACEd.
 388          */
 389         int nr_frozen_tasks;
 390 };
 391
 392 struct cgroup {
 393         /* self css with NULL ->ss, points back to this cgroup */
 394         struct cgroup_subsys_state self;
 395
 396         unsigned long flags;            /* "unsigned long" so bitops work */
 397
 398         /*
 399          * The depth this cgroup is at.  The root is at depth zero and each
 400          * step down the hierarchy increments the level.  This along with
 401          * ancestors[] can determine whether a given cgroup is a
 402          * descendant of another without traversing the hierarchy.
 403          */
 404         int level;
 405
 406         /* Maximum allowed descent tree depth */
 407         int max_depth;
 408
 409         /*
 410          * Keep track of total numbers of visible and dying descent cgroups.
 411          * Dying cgroups are cgroups which were deleted by a user,
 412          * but are still existing because someone else is holding a reference.
 413          * max_descendants is a maximum allowed number of descent cgroups.
 414          *
 415          * nr_descendants and nr_dying_descendants are protected
 416          * by cgroup_mutex and css_set_lock. It's fine to read them holding
 417          * any of cgroup_mutex and css_set_lock; for writing both locks
 418          * should be held.
 419          */
 420         int nr_descendants;
 421         int nr_dying_descendants;
 422         int max_descendants;
 423
 424         /*
 425          * Each non-empty css_set associated with this cgroup contributes
 426          * one to nr_populated_csets.  The counter is zero iff this cgroup
 427          * doesn't have any tasks.
 428          *
 429          * All children which have non-zero nr_populated_csets and/or
 430          * nr_populated_children of their own contribute one to either
 431          * nr_populated_domain_children or nr_populated_threaded_children
 432          * depending on their type.  Each counter is zero iff all cgroups
 433          * of the type in the subtree proper don't have any tasks.
 434          */
 435         int nr_populated_csets;
 436         int nr_populated_domain_children;
 437         int nr_populated_threaded_children;
 438
 439         int nr_threaded_children;       /* # of live threaded child cgroups */
 440
 441         struct kernfs_node *kn;         /* cgroup kernfs entry */
 442         struct cgroup_file procs_file;  /* handle for "cgroup.procs" */
 443         struct cgroup_file events_file; /* handle for "cgroup.events" */
 444
 445         /* handles for "{cpu,memory,io,irq}.pressure" */
 446         struct cgroup_file psi_files[NR_PSI_RESOURCES];
 447
 448         /*
 449          * The bitmask of subsystems enabled on the child cgroups.
 450          * ->subtree_control is the one configured through
 451          * "cgroup.subtree_control" while ->subtree_ss_mask is the effective
 452          * one which may have more subsystems enabled.  Controller knobs
 453          * are made available iff it's enabled in ->subtree_control.
 454          */
 455         u16 subtree_control;
 456         u16 subtree_ss_mask;
 457         u16 old_subtree_control;
 458         u16 old_subtree_ss_mask;
 459
 460         /* Private pointers for each registered subsystem */
 461         struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
 462
 463         struct cgroup_root *root;
 464
 465         /*
 466          * List of cgrp_cset_links pointing at css_sets with tasks in this
 467          * cgroup.  Protected by css_set_lock.
 468          */
 469         struct list_head cset_links;
 470
 471         /*
 472          * On the default hierarchy, a css_set for a cgroup with some
 473          * susbsys disabled will point to css's which are associated with
 474          * the closest ancestor which has the subsys enabled.  The
 475          * following lists all css_sets which point to this cgroup's css
 476          * for the given subsystem.
 477          */
 478         struct list_head e_csets[CGROUP_SUBSYS_COUNT];
 479
 480         /*
 481          * If !threaded, self.  If threaded, it points to the nearest
 482          * domain ancestor.  Inside a threaded subtree, cgroups are exempt
 483          * from process granularity and no-internal-task constraint.
 484          * Domain level resource consumptions which aren't tied to a
 485          * specific task are charged to the dom_cgrp.
 486          */
 487         struct cgroup *dom_cgrp;
 488         struct cgroup *old_dom_cgrp;            /* used while enabling threaded */
 489
 490         /* per-cpu recursive resource statistics */
 491         struct cgroup_rstat_cpu __percpu *rstat_cpu;
 492         struct list_head rstat_css_list;
 493
 494         /* cgroup basic resource statistics */
 495         struct cgroup_base_stat last_bstat;
 496         struct cgroup_base_stat bstat;
 497         struct prev_cputime prev_cputime;       /* for printing out cputime */
 498
 499         /*
 500          * list of pidlists, up to two for each namespace (one for procs, one
 501          * for tasks); created on demand.
 502          */
 503         struct list_head pidlists;
 504         struct mutex pidlist_mutex;
 505
 506         /* used to wait for offlining of csses */
 507         wait_queue_head_t offline_waitq;
 508
 509         /* used to schedule release agent */
 510         struct work_struct release_agent_work;
 511
 512         /* used to track pressure stalls */
 513         struct psi_group *psi;
 514
 515         /* used to store eBPF programs */
 516         struct cgroup_bpf bpf;
 517
 518         /* If there is block congestion on this cgroup. */
 519         atomic_t congestion_count;
 520
 521         /* Used to store internal freezer state */
 522         struct cgroup_freezer_state freezer;
 523
 524 #ifdef CONFIG_BPF_SYSCALL
 525         struct bpf_local_storage __rcu  *bpf_cgrp_storage;
 526 #endif
 527
 528         /* All ancestors including self */
 529         struct cgroup *ancestors[];
 530 };
 531
 532 /*
 533  * A cgroup_root represents the root of a cgroup hierarchy, and may be
 534  * associated with a kernfs_root to form an active hierarchy.  This is
 535  * internal to cgroup core.  Don't access directly from controllers.
 536  */
 537 struct cgroup_root {
 538         struct kernfs_root *kf_root;
 539
 540         /* The bitmask of subsystems attached to this hierarchy */
 541         unsigned int subsys_mask;
 542
 543         /* Unique id for this hierarchy. */
 544         int hierarchy_id;
 545
 546         /*
 547          * The root cgroup. The containing cgroup_root will be destroyed on its
 548          * release. cgrp->ancestors[0] will be used overflowing into the
 549          * following field. cgrp_ancestor_storage must immediately follow.
 550          */
 551         struct cgroup cgrp;
 552
 553         /* must follow cgrp for cgrp->ancestors[0], see above */
 554         struct cgroup *cgrp_ancestor_storage;
 555
 556         /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
 557         atomic_t nr_cgrps;
 558
 559         /* A list running through the active hierarchies */
 560         struct list_head root_list;
 561
 562         /* Hierarchy-specific flags */
 563         unsigned int flags;
 564
 565         /* The path to use for release notifications. */
 566         char release_agent_path[PATH_MAX];
 567
 568         /* The name for this hierarchy - may be empty */
 569         char name[MAX_CGROUP_ROOT_NAMELEN];
 570 };
 571
 572 /*
 573  * struct cftype: handler definitions for cgroup control files
 574  *
 575  * When reading/writing to a file:
 576  *      - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
 577  *      - the 'cftype' of the file is file->f_path.dentry->d_fsdata
 578  */
 579 struct cftype {
 580         /*
 581          * By convention, the name should begin with the name of the
 582          * subsystem, followed by a period.  Zero length string indicates
 583          * end of cftype array.
 584          */
 585         char name[MAX_CFTYPE_NAME];
 586         unsigned long private;
 587
 588         /*
 589          * The maximum length of string, excluding trailing nul, that can
 590          * be passed to write.  If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
 591          */
 592         size_t max_write_len;
 593
 594         /* CFTYPE_* flags */
 595         unsigned int flags;
 596
 597         /*
 598          * If non-zero, should contain the offset from the start of css to
 599          * a struct cgroup_file field.  cgroup will record the handle of
 600          * the created file into it.  The recorded handle can be used as
 601          * long as the containing css remains accessible.
 602          */
 603         unsigned int file_offset;
 604
 605         /*
 606          * Fields used for internal bookkeeping.  Initialized automatically
 607          * during registration.
 608          */
 609         struct cgroup_subsys *ss;       /* NULL for cgroup core files */
 610         struct list_head node;          /* anchored at ss->cfts */
 611         struct kernfs_ops *kf_ops;
 612
 613         int (*open)(struct kernfs_open_file *of);
 614         void (*release)(struct kernfs_open_file *of);
 615
 616         /*
 617          * read_u64() is a shortcut for the common case of returning a
 618          * single integer. Use it in place of read()
 619          */
 620         u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
 621         /*
 622          * read_s64() is a signed version of read_u64()
 623          */
 624         s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
 625
 626         /* generic seq_file read interface */
 627         int (*seq_show)(struct seq_file *sf, void *v);
 628
 629         /* optional ops, implement all or none */
 630         void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
 631         void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
 632         void (*seq_stop)(struct seq_file *sf, void *v);
 633
 634         /*
 635          * write_u64() is a shortcut for the common case of accepting
 636          * a single integer (as parsed by simple_strtoull) from
 637          * userspace. Use in place of write(); return 0 or error.
 638          */
 639         int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
 640                          u64 val);
 641         /*
 642          * write_s64() is a signed version of write_u64()
 643          */
 644         int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
 645                          s64 val);
 646
 647         /*
 648          * write() is the generic write callback which maps directly to
 649          * kernfs write operation and overrides all other operations.
 650          * Maximum write size is determined by ->max_write_len.  Use
 651          * of_css/cft() to access the associated css and cft.
 652          */
 653         ssize_t (*write)(struct kernfs_open_file *of,
 654                          char *buf, size_t nbytes, loff_t off);
 655
 656         __poll_t (*poll)(struct kernfs_open_file *of,
 657                          struct poll_table_struct *pt);
 658
 659 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 660         struct lock_class_key   lockdep_key;
 661 #endif
 662 };
 663
 664 /*
 665  * Control Group subsystem type.
 666  * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
 667  */
 668 struct cgroup_subsys {
 669         struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
 670         int (*css_online)(struct cgroup_subsys_state *css);
 671         void (*css_offline)(struct cgroup_subsys_state *css);
 672         void (*css_released)(struct cgroup_subsys_state *css);
 673         void (*css_free)(struct cgroup_subsys_state *css);
 674         void (*css_reset)(struct cgroup_subsys_state *css);
 675         void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu);
 676         int (*css_extra_stat_show)(struct seq_file *seq,
 677                                    struct cgroup_subsys_state *css);
 678         int (*css_local_stat_show)(struct seq_file *seq,
 679                                    struct cgroup_subsys_state *css);
 680
 681         int (*can_attach)(struct cgroup_taskset *tset);
 682         void (*cancel_attach)(struct cgroup_taskset *tset);
 683         void (*attach)(struct cgroup_taskset *tset);
 684         void (*post_attach)(void);
 685         int (*can_fork)(struct task_struct *task,
 686                         struct css_set *cset);
 687         void (*cancel_fork)(struct task_struct *task, struct css_set *cset);
 688         void (*fork)(struct task_struct *task);
 689         void (*exit)(struct task_struct *task);
 690         void (*release)(struct task_struct *task);
 691         void (*bind)(struct cgroup_subsys_state *root_css);
 692
 693         bool early_init:1;
 694
 695         /*
 696          * If %true, the controller, on the default hierarchy, doesn't show
 697          * up in "cgroup.controllers" or "cgroup.subtree_control", is
 698          * implicitly enabled on all cgroups on the default hierarchy, and
 699          * bypasses the "no internal process" constraint.  This is for
 700          * utility type controllers which is transparent to userland.
 701          *
 702          * An implicit controller can be stolen from the default hierarchy
 703          * anytime and thus must be okay with offline csses from previous
 704          * hierarchies coexisting with csses for the current one.
 705          */
 706         bool implicit_on_dfl:1;
 707
 708         /*
 709          * If %true, the controller, supports threaded mode on the default
 710          * hierarchy.  In a threaded subtree, both process granularity and
 711          * no-internal-process constraint are ignored and a threaded
 712          * controllers should be able to handle that.
 713          *
 714          * Note that as an implicit controller is automatically enabled on
 715          * all cgroups on the default hierarchy, it should also be
 716          * threaded.  implicit && !threaded is not supported.
 717          */
 718         bool threaded:1;
 719
 720         /* the following two fields are initialized automatically during boot */
 721         int id;
 722         const char *name;
 723
 724         /* optional, initialized automatically during boot if not set */
 725         const char *legacy_name;
 726
 727         /* link to parent, protected by cgroup_lock() */
 728         struct cgroup_root *root;
 729
 730         /* idr for css->id */
 731         struct idr css_idr;
 732
 733         /*
 734          * List of cftypes.  Each entry is the first entry of an array
 735          * terminated by zero length name.
 736          */
 737         struct list_head cfts;
 738
 739         /*
 740          * Base cftypes which are automatically registered.  The two can
 741          * point to the same array.
 742          */
 743         struct cftype *dfl_cftypes;     /* for the default hierarchy */
 744         struct cftype *legacy_cftypes;  /* for the legacy hierarchies */
 745
 746         /*
 747          * A subsystem may depend on other subsystems.  When such subsystem
 748          * is enabled on a cgroup, the depended-upon subsystems are enabled
 749          * together if available.  Subsystems enabled due to dependency are
 750          * not visible to userland until explicitly enabled.  The following
 751          * specifies the mask of subsystems that this one depends on.
 752          */
 753         unsigned int depends_on;
 754 };
 755
 756 extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
 757
 758 /**
 759  * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
 760  * @tsk: target task
 761  *
 762  * Allows cgroup operations to synchronize against threadgroup changes
 763  * using a percpu_rw_semaphore.
 764  */
 765 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
 766 {
 767         percpu_down_read(&cgroup_threadgroup_rwsem);
 768 }
 769
 770 /**
 771  * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
 772  * @tsk: target task
 773  *
 774  * Counterpart of cgroup_threadcgroup_change_begin().
 775  */
 776 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
 777 {
 778         percpu_up_read(&cgroup_threadgroup_rwsem);
 779 }
 780
 781 #else   /* CONFIG_CGROUPS */
 782
 783 #define CGROUP_SUBSYS_COUNT 0
 784
 785 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
 786 {
 787         might_sleep();
 788 }
 789
 790 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
 791
 792 #endif  /* CONFIG_CGROUPS */
 793
 794 #ifdef CONFIG_SOCK_CGROUP_DATA
 795
 796 /*
 797  * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
 798  * per-socket cgroup information except for memcg association.
 799  *
 800  * On legacy hierarchies, net_prio and net_cls controllers directly
 801  * set attributes on each sock which can then be tested by the network
 802  * layer. On the default hierarchy, each sock is associated with the
 803  * cgroup it was created in and the networking layer can match the
 804  * cgroup directly.
 805  */
 806 struct sock_cgroup_data {
 807         struct cgroup   *cgroup; /* v2 */
 808 #ifdef CONFIG_CGROUP_NET_CLASSID
 809         u32             classid; /* v1 */
 810 #endif
 811 #ifdef CONFIG_CGROUP_NET_PRIO
 812         u16             prioidx; /* v1 */
 813 #endif
 814 };
 815
 816 static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd)
 817 {
 818 #ifdef CONFIG_CGROUP_NET_PRIO
 819         return READ_ONCE(skcd->prioidx);
 820 #else
 821         return 1;
 822 #endif
 823 }
 824
 825 static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd)
 826 {
 827 #ifdef CONFIG_CGROUP_NET_CLASSID
 828         return READ_ONCE(skcd->classid);
 829 #else
 830         return 0;
 831 #endif
 832 }
 833
 834 static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
 835                                            u16 prioidx)
 836 {
 837 #ifdef CONFIG_CGROUP_NET_PRIO
 838         WRITE_ONCE(skcd->prioidx, prioidx);
 839 #endif
 840 }
 841
 842 static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
 843                                            u32 classid)
 844 {
 845 #ifdef CONFIG_CGROUP_NET_CLASSID
 846         WRITE_ONCE(skcd->classid, classid);
 847 #endif
 848 }
 849
 850 #else   /* CONFIG_SOCK_CGROUP_DATA */
 851
 852 struct sock_cgroup_data {
 853 };
 854
 855 #endif  /* CONFIG_SOCK_CGROUP_DATA */
 856
 857 #endif  /* _LINUX_CGROUP_DEFS_H */