include/linux/cgroup-defs.h

   1 /*
   2  * linux/cgroup-defs.h - basic definitions for cgroup
   3  *
   4  * This file provides basic type and interface.  Include this file directly
   5  * only if necessary to avoid cyclic dependencies.
   6  */
   7 #ifndef _LINUX_CGROUP_DEFS_H
   8 #define _LINUX_CGROUP_DEFS_H
   9
  10 #include <linux/limits.h>
  11 #include <linux/list.h>
  12 #include <linux/idr.h>
  13 #include <linux/wait.h>
  14 #include <linux/mutex.h>
  15 #include <linux/rcupdate.h>
  16 #include <linux/percpu-refcount.h>
  17 #include <linux/percpu-rwsem.h>
  18 #include <linux/workqueue.h>
  19 #include <linux/bpf-cgroup.h>
  20
  21 #ifdef CONFIG_CGROUPS
  22
  23 struct cgroup;
  24 struct cgroup_root;
  25 struct cgroup_subsys;
  26 struct cgroup_taskset;
  27 struct kernfs_node;
  28 struct kernfs_ops;
  29 struct kernfs_open_file;
  30 struct seq_file;
  31
  32 #define MAX_CGROUP_TYPE_NAMELEN 32
  33 #define MAX_CGROUP_ROOT_NAMELEN 64
  34 #define MAX_CFTYPE_NAME         64
  35
  36 /* define the enumeration of all cgroup subsystems */
  37 #define SUBSYS(_x) _x ## _cgrp_id,
  38 enum cgroup_subsys_id {
  39 #include <linux/cgroup_subsys.h>
  40         CGROUP_SUBSYS_COUNT,
  41 };
  42 #undef SUBSYS
  43
  44 /* bits in struct cgroup_subsys_state flags field */
  45 enum {
  46         CSS_NO_REF      = (1 << 0), /* no reference counting for this css */
  47         CSS_ONLINE      = (1 << 1), /* between ->css_online() and ->css_offline() */
  48         CSS_RELEASED    = (1 << 2), /* refcnt reached zero, released */
  49         CSS_VISIBLE     = (1 << 3), /* css is visible to userland */
  50 };
  51
  52 /* bits in struct cgroup flags field */
  53 enum {
  54         /* Control Group requires release notifications to userspace */
  55         CGRP_NOTIFY_ON_RELEASE,
  56         /*
  57          * Clone the parent's configuration when creating a new child
  58          * cpuset cgroup.  For historical reasons, this option can be
  59          * specified at mount time and thus is implemented here.
  60          */
  61         CGRP_CPUSET_CLONE_CHILDREN,
  62 };
  63
  64 /* cgroup_root->flags */
  65 enum {
  66         CGRP_ROOT_NOPREFIX      = (1 << 1), /* mounted subsystems have no named prefix */
  67         CGRP_ROOT_XATTR         = (1 << 2), /* supports extended attributes */
  68 };
  69
  70 /* cftype->flags */
  71 enum {
  72         CFTYPE_ONLY_ON_ROOT     = (1 << 0),     /* only create on root cgrp */
  73         CFTYPE_NOT_ON_ROOT      = (1 << 1),     /* don't create on root cgrp */
  74         CFTYPE_NO_PREFIX        = (1 << 3),     /* (DON'T USE FOR NEW FILES) no subsys prefix */
  75         CFTYPE_WORLD_WRITABLE   = (1 << 4),     /* (DON'T USE FOR NEW FILES) S_IWUGO */
  76
  77         /* internal flags, do not use outside cgroup core proper */
  78         __CFTYPE_ONLY_ON_DFL    = (1 << 16),    /* only on default hierarchy */
  79         __CFTYPE_NOT_ON_DFL     = (1 << 17),    /* not on default hierarchy */
  80 };
  81
  82 /*
  83  * cgroup_file is the handle for a file instance created in a cgroup which
  84  * is used, for example, to generate file changed notifications.  This can
  85  * be obtained by setting cftype->file_offset.
  86  */
  87 struct cgroup_file {
  88         /* do not access any fields from outside cgroup core */
  89         struct kernfs_node *kn;
  90 };
  91
  92 /*
  93  * Per-subsystem/per-cgroup state maintained by the system.  This is the
  94  * fundamental structural building block that controllers deal with.
  95  *
  96  * Fields marked with "PI:" are public and immutable and may be accessed
  97  * directly without synchronization.
  98  */
  99 struct cgroup_subsys_state {
 100         /* PI: the cgroup that this css is attached to */
 101         struct cgroup *cgroup;
 102
 103         /* PI: the cgroup subsystem that this css is attached to */
 104         struct cgroup_subsys *ss;
 105
 106         /* reference count - access via css_[try]get() and css_put() */
 107         struct percpu_ref refcnt;
 108
 109         /* PI: the parent css */
 110         struct cgroup_subsys_state *parent;
 111
 112         /* siblings list anchored at the parent's ->children */
 113         struct list_head sibling;
 114         struct list_head children;
 115
 116         /*
 117          * PI: Subsys-unique ID.  0 is unused and root is always 1.  The
 118          * matching css can be looked up using css_from_id().
 119          */
 120         int id;
 121
 122         unsigned int flags;
 123
 124         /*
 125          * Monotonically increasing unique serial number which defines a
 126          * uniform order among all csses.  It's guaranteed that all
 127          * ->children lists are in the ascending order of ->serial_nr and
 128          * used to allow interrupting and resuming iterations.
 129          */
 130         u64 serial_nr;
 131
 132         /*
 133          * Incremented by online self and children.  Used to guarantee that
 134          * parents are not offlined before their children.
 135          */
 136         atomic_t online_cnt;
 137
 138         /* percpu_ref killing and RCU release */
 139         struct rcu_head rcu_head;
 140         struct work_struct destroy_work;
 141 };
 142
 143 /*
 144  * A css_set is a structure holding pointers to a set of
 145  * cgroup_subsys_state objects. This saves space in the task struct
 146  * object and speeds up fork()/exit(), since a single inc/dec and a
 147  * list_add()/del() can bump the reference count on the entire cgroup
 148  * set for a task.
 149  */
 150 struct css_set {
 151         /*
 152          * Set of subsystem states, one for each subsystem. This array is
 153          * immutable after creation apart from the init_css_set during
 154          * subsystem registration (at boot time).
 155          */
 156         struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
 157
 158         /* reference count */
 159         atomic_t refcount;
 160
 161         /* the default cgroup associated with this css_set */
 162         struct cgroup *dfl_cgrp;
 163
 164         /*
 165          * Lists running through all tasks using this cgroup group.
 166          * mg_tasks lists tasks which belong to this cset but are in the
 167          * process of being migrated out or in.  Protected by
 168          * css_set_rwsem, but, during migration, once tasks are moved to
 169          * mg_tasks, it can be read safely while holding cgroup_mutex.
 170          */
 171         struct list_head tasks;
 172         struct list_head mg_tasks;
 173
 174         /* all css_task_iters currently walking this cset */
 175         struct list_head task_iters;
 176
 177         /*
 178          * On the default hierarhcy, ->subsys[ssid] may point to a css
 179          * attached to an ancestor instead of the cgroup this css_set is
 180          * associated with.  The following node is anchored at
 181          * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
 182          * iterate through all css's attached to a given cgroup.
 183          */
 184         struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
 185
 186         /*
 187          * List running through all cgroup groups in the same hash
 188          * slot. Protected by css_set_lock
 189          */
 190         struct hlist_node hlist;
 191
 192         /*
 193          * List of cgrp_cset_links pointing at cgroups referenced from this
 194          * css_set.  Protected by css_set_lock.
 195          */
 196         struct list_head cgrp_links;
 197
 198         /*
 199          * List of csets participating in the on-going migration either as
 200          * source or destination.  Protected by cgroup_mutex.
 201          */
 202         struct list_head mg_preload_node;
 203         struct list_head mg_node;
 204
 205         /*
 206          * If this cset is acting as the source of migration the following
 207          * two fields are set.  mg_src_cgrp and mg_dst_cgrp are
 208          * respectively the source and destination cgroups of the on-going
 209          * migration.  mg_dst_cset is the destination cset the target tasks
 210          * on this cset should be migrated to.  Protected by cgroup_mutex.
 211          */
 212         struct cgroup *mg_src_cgrp;
 213         struct cgroup *mg_dst_cgrp;
 214         struct css_set *mg_dst_cset;
 215
 216         /* dead and being drained, ignore for migration */
 217         bool dead;
 218
 219         /* For RCU-protected deletion */
 220         struct rcu_head rcu_head;
 221 };
 222
 223 struct cgroup {
 224         /* self css with NULL ->ss, points back to this cgroup */
 225         struct cgroup_subsys_state self;
 226
 227         unsigned long flags;            /* "unsigned long" so bitops work */
 228
 229         /*
 230          * idr allocated in-hierarchy ID.
 231          *
 232          * ID 0 is not used, the ID of the root cgroup is always 1, and a
 233          * new cgroup will be assigned with a smallest available ID.
 234          *
 235          * Allocating/Removing ID must be protected by cgroup_mutex.
 236          */
 237         int id;
 238
 239         /*
 240          * The depth this cgroup is at.  The root is at depth zero and each
 241          * step down the hierarchy increments the level.  This along with
 242          * ancestor_ids[] can determine whether a given cgroup is a
 243          * descendant of another without traversing the hierarchy.
 244          */
 245         int level;
 246
 247         /*
 248          * Each non-empty css_set associated with this cgroup contributes
 249          * one to populated_cnt.  All children with non-zero popuplated_cnt
 250          * of their own contribute one.  The count is zero iff there's no
 251          * task in this cgroup or its subtree.
 252          */
 253         int populated_cnt;
 254
 255         struct kernfs_node *kn;         /* cgroup kernfs entry */
 256         struct cgroup_file procs_file;  /* handle for "cgroup.procs" */
 257         struct cgroup_file events_file; /* handle for "cgroup.events" */
 258
 259         /*
 260          * The bitmask of subsystems enabled on the child cgroups.
 261          * ->subtree_control is the one configured through
 262          * "cgroup.subtree_control" while ->child_ss_mask is the effective
 263          * one which may have more subsystems enabled.  Controller knobs
 264          * are made available iff it's enabled in ->subtree_control.
 265          */
 266         u16 subtree_control;
 267         u16 subtree_ss_mask;
 268         u16 old_subtree_control;
 269         u16 old_subtree_ss_mask;
 270
 271         /* Private pointers for each registered subsystem */
 272         struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
 273
 274         struct cgroup_root *root;
 275
 276         /*
 277          * List of cgrp_cset_links pointing at css_sets with tasks in this
 278          * cgroup.  Protected by css_set_lock.
 279          */
 280         struct list_head cset_links;
 281
 282         /*
 283          * On the default hierarchy, a css_set for a cgroup with some
 284          * susbsys disabled will point to css's which are associated with
 285          * the closest ancestor which has the subsys enabled.  The
 286          * following lists all css_sets which point to this cgroup's css
 287          * for the given subsystem.
 288          */
 289         struct list_head e_csets[CGROUP_SUBSYS_COUNT];
 290
 291         /*
 292          * list of pidlists, up to two for each namespace (one for procs, one
 293          * for tasks); created on demand.
 294          */
 295         struct list_head pidlists;
 296         struct mutex pidlist_mutex;
 297
 298         /* used to wait for offlining of csses */
 299         wait_queue_head_t offline_waitq;
 300
 301         /* used to schedule release agent */
 302         struct work_struct release_agent_work;
 303
 304         /* used to store eBPF programs */
 305         struct cgroup_bpf bpf;
 306
 307         /* ids of the ancestors at each level including self */
 308         int ancestor_ids[];
 309 };
 310
 311 /*
 312  * A cgroup_root represents the root of a cgroup hierarchy, and may be
 313  * associated with a kernfs_root to form an active hierarchy.  This is
 314  * internal to cgroup core.  Don't access directly from controllers.
 315  */
 316 struct cgroup_root {
 317         struct kernfs_root *kf_root;
 318
 319         /* The bitmask of subsystems attached to this hierarchy */
 320         unsigned int subsys_mask;
 321
 322         /* Unique id for this hierarchy. */
 323         int hierarchy_id;
 324
 325         /* The root cgroup.  Root is destroyed on its release. */
 326         struct cgroup cgrp;
 327
 328         /* for cgrp->ancestor_ids[0] */
 329         int cgrp_ancestor_id_storage;
 330
 331         /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
 332         atomic_t nr_cgrps;
 333
 334         /* A list running through the active hierarchies */
 335         struct list_head root_list;
 336
 337         /* Hierarchy-specific flags */
 338         unsigned int flags;
 339
 340         /* IDs for cgroups in this hierarchy */
 341         struct idr cgroup_idr;
 342
 343         /* The path to use for release notifications. */
 344         char release_agent_path[PATH_MAX];
 345
 346         /* The name for this hierarchy - may be empty */
 347         char name[MAX_CGROUP_ROOT_NAMELEN];
 348 };
 349
 350 /*
 351  * struct cftype: handler definitions for cgroup control files
 352  *
 353  * When reading/writing to a file:
 354  *      - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
 355  *      - the 'cftype' of the file is file->f_path.dentry->d_fsdata
 356  */
 357 struct cftype {
 358         /*
 359          * By convention, the name should begin with the name of the
 360          * subsystem, followed by a period.  Zero length string indicates
 361          * end of cftype array.
 362          */
 363         char name[MAX_CFTYPE_NAME];
 364         unsigned long private;
 365
 366         /*
 367          * The maximum length of string, excluding trailing nul, that can
 368          * be passed to write.  If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
 369          */
 370         size_t max_write_len;
 371
 372         /* CFTYPE_* flags */
 373         unsigned int flags;
 374
 375         /*
 376          * If non-zero, should contain the offset from the start of css to
 377          * a struct cgroup_file field.  cgroup will record the handle of
 378          * the created file into it.  The recorded handle can be used as
 379          * long as the containing css remains accessible.
 380          */
 381         unsigned int file_offset;
 382
 383         /*
 384          * Fields used for internal bookkeeping.  Initialized automatically
 385          * during registration.
 386          */
 387         struct cgroup_subsys *ss;       /* NULL for cgroup core files */
 388         struct list_head node;          /* anchored at ss->cfts */
 389         struct kernfs_ops *kf_ops;
 390
 391         int (*open)(struct kernfs_open_file *of);
 392         void (*release)(struct kernfs_open_file *of);
 393
 394         /*
 395          * read_u64() is a shortcut for the common case of returning a
 396          * single integer. Use it in place of read()
 397          */
 398         u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
 399         /*
 400          * read_s64() is a signed version of read_u64()
 401          */
 402         s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
 403
 404         /* generic seq_file read interface */
 405         int (*seq_show)(struct seq_file *sf, void *v);
 406
 407         /* optional ops, implement all or none */
 408         void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
 409         void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
 410         void (*seq_stop)(struct seq_file *sf, void *v);
 411
 412         /*
 413          * write_u64() is a shortcut for the common case of accepting
 414          * a single integer (as parsed by simple_strtoull) from
 415          * userspace. Use in place of write(); return 0 or error.
 416          */
 417         int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
 418                          u64 val);
 419         /*
 420          * write_s64() is a signed version of write_u64()
 421          */
 422         int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
 423                          s64 val);
 424
 425         /*
 426          * write() is the generic write callback which maps directly to
 427          * kernfs write operation and overrides all other operations.
 428          * Maximum write size is determined by ->max_write_len.  Use
 429          * of_css/cft() to access the associated css and cft.
 430          */
 431         ssize_t (*write)(struct kernfs_open_file *of,
 432                          char *buf, size_t nbytes, loff_t off);
 433
 434 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 435         struct lock_class_key   lockdep_key;
 436 #endif
 437 };
 438
 439 /*
 440  * Control Group subsystem type.
 441  * See Documentation/cgroups/cgroups.txt for details
 442  */
 443 struct cgroup_subsys {
 444         struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
 445         int (*css_online)(struct cgroup_subsys_state *css);
 446         void (*css_offline)(struct cgroup_subsys_state *css);
 447         void (*css_released)(struct cgroup_subsys_state *css);
 448         void (*css_free)(struct cgroup_subsys_state *css);
 449         void (*css_reset)(struct cgroup_subsys_state *css);
 450
 451         int (*can_attach)(struct cgroup_taskset *tset);
 452         void (*cancel_attach)(struct cgroup_taskset *tset);
 453         void (*attach)(struct cgroup_taskset *tset);
 454         void (*post_attach)(void);
 455         int (*can_fork)(struct task_struct *task);
 456         void (*cancel_fork)(struct task_struct *task);
 457         void (*fork)(struct task_struct *task);
 458         void (*exit)(struct task_struct *task);
 459         void (*free)(struct task_struct *task);
 460         void (*bind)(struct cgroup_subsys_state *root_css);
 461
 462         bool early_init:1;
 463
 464         /*
 465          * If %true, the controller, on the default hierarchy, doesn't show
 466          * up in "cgroup.controllers" or "cgroup.subtree_control", is
 467          * implicitly enabled on all cgroups on the default hierarchy, and
 468          * bypasses the "no internal process" constraint.  This is for
 469          * utility type controllers which is transparent to userland.
 470          *
 471          * An implicit controller can be stolen from the default hierarchy
 472          * anytime and thus must be okay with offline csses from previous
 473          * hierarchies coexisting with csses for the current one.
 474          */
 475         bool implicit_on_dfl:1;
 476
 477         /*
 478          * If %false, this subsystem is properly hierarchical -
 479          * configuration, resource accounting and restriction on a parent
 480          * cgroup cover those of its children.  If %true, hierarchy support
 481          * is broken in some ways - some subsystems ignore hierarchy
 482          * completely while others are only implemented half-way.
 483          *
 484          * It's now disallowed to create nested cgroups if the subsystem is
 485          * broken and cgroup core will emit a warning message on such
 486          * cases.  Eventually, all subsystems will be made properly
 487          * hierarchical and this will go away.
 488          */
 489         bool broken_hierarchy:1;
 490         bool warned_broken_hierarchy:1;
 491
 492         /* the following two fields are initialized automtically during boot */
 493         int id;
 494         const char *name;
 495
 496         /* optional, initialized automatically during boot if not set */
 497         const char *legacy_name;
 498
 499         /* link to parent, protected by cgroup_lock() */
 500         struct cgroup_root *root;
 501
 502         /* idr for css->id */
 503         struct idr css_idr;
 504
 505         /*
 506          * List of cftypes.  Each entry is the first entry of an array
 507          * terminated by zero length name.
 508          */
 509         struct list_head cfts;
 510
 511         /*
 512          * Base cftypes which are automatically registered.  The two can
 513          * point to the same array.
 514          */
 515         struct cftype *dfl_cftypes;     /* for the default hierarchy */
 516         struct cftype *legacy_cftypes;  /* for the legacy hierarchies */
 517
 518         /*
 519          * A subsystem may depend on other subsystems.  When such subsystem
 520          * is enabled on a cgroup, the depended-upon subsystems are enabled
 521          * together if available.  Subsystems enabled due to dependency are
 522          * not visible to userland until explicitly enabled.  The following
 523          * specifies the mask of subsystems that this one depends on.
 524          */
 525         unsigned int depends_on;
 526 };
 527
 528 extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
 529
 530 /**
 531  * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
 532  * @tsk: target task
 533  *
 534  * Called from threadgroup_change_begin() and allows cgroup operations to
 535  * synchronize against threadgroup changes using a percpu_rw_semaphore.
 536  */
 537 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
 538 {
 539         percpu_down_read(&cgroup_threadgroup_rwsem);
 540 }
 541
 542 /**
 543  * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
 544  * @tsk: target task
 545  *
 546  * Called from threadgroup_change_end().  Counterpart of
 547  * cgroup_threadcgroup_change_begin().
 548  */
 549 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
 550 {
 551         percpu_up_read(&cgroup_threadgroup_rwsem);
 552 }
 553
 554 #else   /* CONFIG_CGROUPS */
 555
 556 #define CGROUP_SUBSYS_COUNT 0
 557
 558 static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
 559 static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
 560
 561 #endif  /* CONFIG_CGROUPS */
 562
 563 #ifdef CONFIG_SOCK_CGROUP_DATA
 564
 565 /*
 566  * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains
 567  * per-socket cgroup information except for memcg association.
 568  *
 569  * On legacy hierarchies, net_prio and net_cls controllers directly set
 570  * attributes on each sock which can then be tested by the network layer.
 571  * On the default hierarchy, each sock is associated with the cgroup it was
 572  * created in and the networking layer can match the cgroup directly.
 573  *
 574  * To avoid carrying all three cgroup related fields separately in sock,
 575  * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer.
 576  * On boot, sock_cgroup_data records the cgroup that the sock was created
 577  * in so that cgroup2 matches can be made; however, once either net_prio or
 578  * net_cls starts being used, the area is overriden to carry prioidx and/or
 579  * classid.  The two modes are distinguished by whether the lowest bit is
 580  * set.  Clear bit indicates cgroup pointer while set bit prioidx and
 581  * classid.
 582  *
 583  * While userland may start using net_prio or net_cls at any time, once
 584  * either is used, cgroup2 matching no longer works.  There is no reason to
 585  * mix the two and this is in line with how legacy and v2 compatibility is
 586  * handled.  On mode switch, cgroup references which are already being
 587  * pointed to by socks may be leaked.  While this can be remedied by adding
 588  * synchronization around sock_cgroup_data, given that the number of leaked
 589  * cgroups is bound and highly unlikely to be high, this seems to be the
 590  * better trade-off.
 591  */
 592 struct sock_cgroup_data {
 593         union {
 594 #ifdef __LITTLE_ENDIAN
 595                 struct {
 596                         u8      is_data;
 597                         u8      padding;
 598                         u16     prioidx;
 599                         u32     classid;
 600                 } __packed;
 601 #else
 602                 struct {
 603                         u32     classid;
 604                         u16     prioidx;
 605                         u8      padding;
 606                         u8      is_data;
 607                 } __packed;
 608 #endif
 609                 u64             val;
 610         };
 611 };
 612
 613 /*
 614  * There's a theoretical window where the following accessors race with
 615  * updaters and return part of the previous pointer as the prioidx or
 616  * classid.  Such races are short-lived and the result isn't critical.
 617  */
 618 static inline u16 sock_cgroup_prioidx(struct sock_cgroup_data *skcd)
 619 {
 620         /* fallback to 1 which is always the ID of the root cgroup */
 621         return (skcd->is_data & 1) ? skcd->prioidx : 1;
 622 }
 623
 624 static inline u32 sock_cgroup_classid(struct sock_cgroup_data *skcd)
 625 {
 626         /* fallback to 0 which is the unconfigured default classid */
 627         return (skcd->is_data & 1) ? skcd->classid : 0;
 628 }
 629
 630 /*
 631  * If invoked concurrently, the updaters may clobber each other.  The
 632  * caller is responsible for synchronization.
 633  */
 634 static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd,
 635                                            u16 prioidx)
 636 {
 637         struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
 638
 639         if (sock_cgroup_prioidx(&skcd_buf) == prioidx)
 640                 return;
 641
 642         if (!(skcd_buf.is_data & 1)) {
 643                 skcd_buf.val = 0;
 644                 skcd_buf.is_data = 1;
 645         }
 646
 647         skcd_buf.prioidx = prioidx;
 648         WRITE_ONCE(skcd->val, skcd_buf.val);    /* see sock_cgroup_ptr() */
 649 }
 650
 651 static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd,
 652                                            u32 classid)
 653 {
 654         struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }};
 655
 656         if (sock_cgroup_classid(&skcd_buf) == classid)
 657                 return;
 658
 659         if (!(skcd_buf.is_data & 1)) {
 660                 skcd_buf.val = 0;
 661                 skcd_buf.is_data = 1;
 662         }
 663
 664         skcd_buf.classid = classid;
 665         WRITE_ONCE(skcd->val, skcd_buf.val);    /* see sock_cgroup_ptr() */
 666 }
 667
 668 #else   /* CONFIG_SOCK_CGROUP_DATA */
 669
 670 struct sock_cgroup_data {
 671 };
 672
 673 #endif  /* CONFIG_SOCK_CGROUP_DATA */
 674
 675 #endif  /* _LINUX_CGROUP_DEFS_H */