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/workqueue.h> 21#include <linux/bpf-cgroup.h> 22 23#ifdef CONFIG_CGROUPS 24 25struct cgroup; 26struct cgroup_root; 27struct cgroup_subsys; 28struct cgroup_taskset; 29struct kernfs_node; 30struct kernfs_ops; 31struct kernfs_open_file; 32struct seq_file; 33 34#define MAX_CGROUP_TYPE_NAMELEN 32 35#define MAX_CGROUP_ROOT_NAMELEN 64 36#define MAX_CFTYPE_NAME 64 37 38/* define the enumeration of all cgroup subsystems */ 39#define SUBSYS(_x) _x ## _cgrp_id, 40enum cgroup_subsys_id { 41#include <linux/cgroup_subsys.h> 42 CGROUP_SUBSYS_COUNT, 43}; 44#undef SUBSYS 45 46/* bits in struct cgroup_subsys_state flags field */ 47enum { 48 CSS_NO_REF = (1 << 0), /* no reference counting for this css */ 49 CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ 50 CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */ 51 CSS_VISIBLE = (1 << 3), /* css is visible to userland */ 52 CSS_DYING = (1 << 4), /* css is dying */ 53}; 54 55/* bits in struct cgroup flags field */ 56enum { 57 /* Control Group requires release notifications to userspace */ 58 CGRP_NOTIFY_ON_RELEASE, 59 /* 60 * Clone the parent's configuration when creating a new child 61 * cpuset cgroup. For historical reasons, this option can be 62 * specified at mount time and thus is implemented here. 63 */ 64 CGRP_CPUSET_CLONE_CHILDREN, 65}; 66 67/* cgroup_root->flags */ 68enum { 69 CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ 70 CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ 71 72 /* 73 * Consider namespaces as delegation boundaries. If this flag is 74 * set, controller specific interface files in a namespace root 75 * aren't writeable from inside the namespace. 76 */ 77 CGRP_ROOT_NS_DELEGATE = (1 << 3), 78 79 /* 80 * Enable cpuset controller in v1 cgroup to use v2 behavior. 81 */ 82 CGRP_ROOT_CPUSET_V2_MODE = (1 << 4), 83}; 84 85/* cftype->flags */ 86enum { 87 CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */ 88 CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */ 89 CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */ 90 91 CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ 92 CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */ 93 94 /* internal flags, do not use outside cgroup core proper */ 95 __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ 96 __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */ 97}; 98 99/* 100 * cgroup_file is the handle for a file instance created in a cgroup which 101 * is used, for example, to generate file changed notifications. This can 102 * be obtained by setting cftype->file_offset. 103 */ 104struct cgroup_file { 105 /* do not access any fields from outside cgroup core */ 106 struct kernfs_node *kn; 107}; 108 109/* 110 * Per-subsystem/per-cgroup state maintained by the system. This is the 111 * fundamental structural building block that controllers deal with. 112 * 113 * Fields marked with "PI:" are public and immutable and may be accessed 114 * directly without synchronization. 115 */ 116struct cgroup_subsys_state { 117 /* PI: the cgroup that this css is attached to */ 118 struct cgroup *cgroup; 119 120 /* PI: the cgroup subsystem that this css is attached to */ 121 struct cgroup_subsys *ss; 122 123 /* reference count - access via css_[try]get() and css_put() */ 124 struct percpu_ref refcnt; 125 126 /* siblings list anchored at the parent's ->children */ 127 struct list_head sibling; 128 struct list_head children; 129 130 /* 131 * PI: Subsys-unique ID. 0 is unused and root is always 1. The 132 * matching css can be looked up using css_from_id(). 133 */ 134 int id; 135 136 unsigned int flags; 137 138 /* 139 * Monotonically increasing unique serial number which defines a 140 * uniform order among all csses. It's guaranteed that all 141 * ->children lists are in the ascending order of ->serial_nr and 142 * used to allow interrupting and resuming iterations. 143 */ 144 u64 serial_nr; 145 146 /* 147 * Incremented by online self and children. Used to guarantee that 148 * parents are not offlined before their children. 149 */ 150 atomic_t online_cnt; 151 152 /* percpu_ref killing and RCU release */ 153 struct rcu_head rcu_head; 154 struct work_struct destroy_work; 155 156 /* 157 * PI: the parent css. Placed here for cache proximity to following 158 * fields of the containing structure. 159 */ 160 struct cgroup_subsys_state *parent; 161}; 162 163/* 164 * A css_set is a structure holding pointers to a set of 165 * cgroup_subsys_state objects. This saves space in the task struct 166 * object and speeds up fork()/exit(), since a single inc/dec and a 167 * list_add()/del() can bump the reference count on the entire cgroup 168 * set for a task. 169 */ 170struct css_set { 171 /* 172 * Set of subsystem states, one for each subsystem. This array is 173 * immutable after creation apart from the init_css_set during 174 * subsystem registration (at boot time). 175 */ 176 struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; 177 178 /* reference count */ 179 refcount_t refcount; 180 181 /* 182 * For a domain cgroup, the following points to self. If threaded, 183 * to the matching cset of the nearest domain ancestor. The 184 * dom_cset provides access to the domain cgroup and its csses to 185 * which domain level resource consumptions should be charged. 186 */ 187 struct css_set *dom_cset; 188 189 /* the default cgroup associated with this css_set */ 190 struct cgroup *dfl_cgrp; 191 192 /* internal task count, protected by css_set_lock */ 193 int nr_tasks; 194 195 /* 196 * Lists running through all tasks using this cgroup group. 197 * mg_tasks lists tasks which belong to this cset but are in the 198 * process of being migrated out or in. Protected by 199 * css_set_rwsem, but, during migration, once tasks are moved to 200 * mg_tasks, it can be read safely while holding cgroup_mutex. 201 */ 202 struct list_head tasks; 203 struct list_head mg_tasks; 204 205 /* all css_task_iters currently walking this cset */ 206 struct list_head task_iters; 207 208 /* 209 * On the default hierarhcy, ->subsys[ssid] may point to a css 210 * attached to an ancestor instead of the cgroup this css_set is 211 * associated with. The following node is anchored at 212 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to 213 * iterate through all css's attached to a given cgroup. 214 */ 215 struct list_head e_cset_node[CGROUP_SUBSYS_COUNT]; 216 217 /* all threaded csets whose ->dom_cset points to this cset */ 218 struct list_head threaded_csets; 219 struct list_head threaded_csets_node; 220 221 /* 222 * List running through all cgroup groups in the same hash 223 * slot. Protected by css_set_lock 224 */ 225 struct hlist_node hlist; 226 227 /* 228 * List of cgrp_cset_links pointing at cgroups referenced from this 229 * css_set. Protected by css_set_lock. 230 */ 231 struct list_head cgrp_links; 232 233 /* 234 * List of csets participating in the on-going migration either as 235 * source or destination. Protected by cgroup_mutex. 236 */ 237 struct list_head mg_preload_node; 238 struct list_head mg_node; 239 240 /* 241 * If this cset is acting as the source of migration the following 242 * two fields are set. mg_src_cgrp and mg_dst_cgrp are 243 * respectively the source and destination cgroups of the on-going 244 * migration. mg_dst_cset is the destination cset the target tasks 245 * on this cset should be migrated to. Protected by cgroup_mutex. 246 */ 247 struct cgroup *mg_src_cgrp; 248 struct cgroup *mg_dst_cgrp; 249 struct css_set *mg_dst_cset; 250 251 /* dead and being drained, ignore for migration */ 252 bool dead; 253 254 /* For RCU-protected deletion */ 255 struct rcu_head rcu_head; 256}; 257 258struct cgroup { 259 /* self css with NULL ->ss, points back to this cgroup */ 260 struct cgroup_subsys_state self; 261 262 unsigned long flags; /* "unsigned long" so bitops work */ 263 264 /* 265 * idr allocated in-hierarchy ID. 266 * 267 * ID 0 is not used, the ID of the root cgroup is always 1, and a 268 * new cgroup will be assigned with a smallest available ID. 269 * 270 * Allocating/Removing ID must be protected by cgroup_mutex. 271 */ 272 int id; 273 274 /* 275 * The depth this cgroup is at. The root is at depth zero and each 276 * step down the hierarchy increments the level. This along with 277 * ancestor_ids[] can determine whether a given cgroup is a 278 * descendant of another without traversing the hierarchy. 279 */ 280 int level; 281 282 /* Maximum allowed descent tree depth */ 283 int max_depth; 284 285 /* 286 * Keep track of total numbers of visible and dying descent cgroups. 287 * Dying cgroups are cgroups which were deleted by a user, 288 * but are still existing because someone else is holding a reference. 289 * max_descendants is a maximum allowed number of descent cgroups. 290 */ 291 int nr_descendants; 292 int nr_dying_descendants; 293 int max_descendants; 294 295 /* 296 * Each non-empty css_set associated with this cgroup contributes 297 * one to nr_populated_csets. The counter is zero iff this cgroup 298 * doesn't have any tasks. 299 * 300 * All children which have non-zero nr_populated_csets and/or 301 * nr_populated_children of their own contribute one to either 302 * nr_populated_domain_children or nr_populated_threaded_children 303 * depending on their type. Each counter is zero iff all cgroups 304 * of the type in the subtree proper don't have any tasks. 305 */ 306 int nr_populated_csets; 307 int nr_populated_domain_children; 308 int nr_populated_threaded_children; 309 310 int nr_threaded_children; /* # of live threaded child cgroups */ 311 312 struct kernfs_node *kn; /* cgroup kernfs entry */ 313 struct cgroup_file procs_file; /* handle for "cgroup.procs" */ 314 struct cgroup_file events_file; /* handle for "cgroup.events" */ 315 316 /* 317 * The bitmask of subsystems enabled on the child cgroups. 318 * ->subtree_control is the one configured through 319 * "cgroup.subtree_control" while ->child_ss_mask is the effective 320 * one which may have more subsystems enabled. Controller knobs 321 * are made available iff it's enabled in ->subtree_control. 322 */ 323 u16 subtree_control; 324 u16 subtree_ss_mask; 325 u16 old_subtree_control; 326 u16 old_subtree_ss_mask; 327 328 /* Private pointers for each registered subsystem */ 329 struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT]; 330 331 struct cgroup_root *root; 332 333 /* 334 * List of cgrp_cset_links pointing at css_sets with tasks in this 335 * cgroup. Protected by css_set_lock. 336 */ 337 struct list_head cset_links; 338 339 /* 340 * On the default hierarchy, a css_set for a cgroup with some 341 * susbsys disabled will point to css's which are associated with 342 * the closest ancestor which has the subsys enabled. The 343 * following lists all css_sets which point to this cgroup's css 344 * for the given subsystem. 345 */ 346 struct list_head e_csets[CGROUP_SUBSYS_COUNT]; 347 348 /* 349 * If !threaded, self. If threaded, it points to the nearest 350 * domain ancestor. Inside a threaded subtree, cgroups are exempt 351 * from process granularity and no-internal-task constraint. 352 * Domain level resource consumptions which aren't tied to a 353 * specific task are charged to the dom_cgrp. 354 */ 355 struct cgroup *dom_cgrp; 356 357 /* 358 * list of pidlists, up to two for each namespace (one for procs, one 359 * for tasks); created on demand. 360 */ 361 struct list_head pidlists; 362 struct mutex pidlist_mutex; 363 364 /* used to wait for offlining of csses */ 365 wait_queue_head_t offline_waitq; 366 367 /* used to schedule release agent */ 368 struct work_struct release_agent_work; 369 370 /* used to store eBPF programs */ 371 struct cgroup_bpf bpf; 372 373 /* ids of the ancestors at each level including self */ 374 int ancestor_ids[]; 375}; 376 377/* 378 * A cgroup_root represents the root of a cgroup hierarchy, and may be 379 * associated with a kernfs_root to form an active hierarchy. This is 380 * internal to cgroup core. Don't access directly from controllers. 381 */ 382struct cgroup_root { 383 struct kernfs_root *kf_root; 384 385 /* The bitmask of subsystems attached to this hierarchy */ 386 unsigned int subsys_mask; 387 388 /* Unique id for this hierarchy. */ 389 int hierarchy_id; 390 391 /* The root cgroup. Root is destroyed on its release. */ 392 struct cgroup cgrp; 393 394 /* for cgrp->ancestor_ids[0] */ 395 int cgrp_ancestor_id_storage; 396 397 /* Number of cgroups in the hierarchy, used only for /proc/cgroups */ 398 atomic_t nr_cgrps; 399 400 /* A list running through the active hierarchies */ 401 struct list_head root_list; 402 403 /* Hierarchy-specific flags */ 404 unsigned int flags; 405 406 /* IDs for cgroups in this hierarchy */ 407 struct idr cgroup_idr; 408 409 /* The path to use for release notifications. */ 410 char release_agent_path[PATH_MAX]; 411 412 /* The name for this hierarchy - may be empty */ 413 char name[MAX_CGROUP_ROOT_NAMELEN]; 414}; 415 416/* 417 * struct cftype: handler definitions for cgroup control files 418 * 419 * When reading/writing to a file: 420 * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata 421 * - the 'cftype' of the file is file->f_path.dentry->d_fsdata 422 */ 423struct cftype { 424 /* 425 * By convention, the name should begin with the name of the 426 * subsystem, followed by a period. Zero length string indicates 427 * end of cftype array. 428 */ 429 char name[MAX_CFTYPE_NAME]; 430 unsigned long private; 431 432 /* 433 * The maximum length of string, excluding trailing nul, that can 434 * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed. 435 */ 436 size_t max_write_len; 437 438 /* CFTYPE_* flags */ 439 unsigned int flags; 440 441 /* 442 * If non-zero, should contain the offset from the start of css to 443 * a struct cgroup_file field. cgroup will record the handle of 444 * the created file into it. The recorded handle can be used as 445 * long as the containing css remains accessible. 446 */ 447 unsigned int file_offset; 448 449 /* 450 * Fields used for internal bookkeeping. Initialized automatically 451 * during registration. 452 */ 453 struct cgroup_subsys *ss; /* NULL for cgroup core files */ 454 struct list_head node; /* anchored at ss->cfts */ 455 struct kernfs_ops *kf_ops; 456 457 int (*open)(struct kernfs_open_file *of); 458 void (*release)(struct kernfs_open_file *of); 459 460 /* 461 * read_u64() is a shortcut for the common case of returning a 462 * single integer. Use it in place of read() 463 */ 464 u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft); 465 /* 466 * read_s64() is a signed version of read_u64() 467 */ 468 s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); 469 470 /* generic seq_file read interface */ 471 int (*seq_show)(struct seq_file *sf, void *v); 472 473 /* optional ops, implement all or none */ 474 void *(*seq_start)(struct seq_file *sf, loff_t *ppos); 475 void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); 476 void (*seq_stop)(struct seq_file *sf, void *v); 477 478 /* 479 * write_u64() is a shortcut for the common case of accepting 480 * a single integer (as parsed by simple_strtoull) from 481 * userspace. Use in place of write(); return 0 or error. 482 */ 483 int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft, 484 u64 val); 485 /* 486 * write_s64() is a signed version of write_u64() 487 */ 488 int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft, 489 s64 val); 490 491 /* 492 * write() is the generic write callback which maps directly to 493 * kernfs write operation and overrides all other operations. 494 * Maximum write size is determined by ->max_write_len. Use 495 * of_css/cft() to access the associated css and cft. 496 */ 497 ssize_t (*write)(struct kernfs_open_file *of, 498 char *buf, size_t nbytes, loff_t off); 499 500#ifdef CONFIG_DEBUG_LOCK_ALLOC 501 struct lock_class_key lockdep_key; 502#endif 503}; 504 505/* 506 * Control Group subsystem type. 507 * See Documentation/cgroups/cgroups.txt for details 508 */ 509struct cgroup_subsys { 510 struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css); 511 int (*css_online)(struct cgroup_subsys_state *css); 512 void (*css_offline)(struct cgroup_subsys_state *css); 513 void (*css_released)(struct cgroup_subsys_state *css); 514 void (*css_free)(struct cgroup_subsys_state *css); 515 void (*css_reset)(struct cgroup_subsys_state *css); 516 517 int (*can_attach)(struct cgroup_taskset *tset); 518 void (*cancel_attach)(struct cgroup_taskset *tset); 519 void (*attach)(struct cgroup_taskset *tset); 520 void (*post_attach)(void); 521 int (*can_fork)(struct task_struct *task); 522 void (*cancel_fork)(struct task_struct *task); 523 void (*fork)(struct task_struct *task); 524 void (*exit)(struct task_struct *task); 525 void (*free)(struct task_struct *task); 526 void (*bind)(struct cgroup_subsys_state *root_css); 527 528 bool early_init:1; 529 530 /* 531 * If %true, the controller, on the default hierarchy, doesn't show 532 * up in "cgroup.controllers" or "cgroup.subtree_control", is 533 * implicitly enabled on all cgroups on the default hierarchy, and 534 * bypasses the "no internal process" constraint. This is for 535 * utility type controllers which is transparent to userland. 536 * 537 * An implicit controller can be stolen from the default hierarchy 538 * anytime and thus must be okay with offline csses from previous 539 * hierarchies coexisting with csses for the current one. 540 */ 541 bool implicit_on_dfl:1; 542 543 /* 544 * If %true, the controller, supports threaded mode on the default 545 * hierarchy. In a threaded subtree, both process granularity and 546 * no-internal-process constraint are ignored and a threaded 547 * controllers should be able to handle that. 548 * 549 * Note that as an implicit controller is automatically enabled on 550 * all cgroups on the default hierarchy, it should also be 551 * threaded. implicit && !threaded is not supported. 552 */ 553 bool threaded:1; 554 555 /* 556 * If %false, this subsystem is properly hierarchical - 557 * configuration, resource accounting and restriction on a parent 558 * cgroup cover those of its children. If %true, hierarchy support 559 * is broken in some ways - some subsystems ignore hierarchy 560 * completely while others are only implemented half-way. 561 * 562 * It's now disallowed to create nested cgroups if the subsystem is 563 * broken and cgroup core will emit a warning message on such 564 * cases. Eventually, all subsystems will be made properly 565 * hierarchical and this will go away. 566 */ 567 bool broken_hierarchy:1; 568 bool warned_broken_hierarchy:1; 569 570 /* the following two fields are initialized automtically during boot */ 571 int id; 572 const char *name; 573 574 /* optional, initialized automatically during boot if not set */ 575 const char *legacy_name; 576 577 /* link to parent, protected by cgroup_lock() */ 578 struct cgroup_root *root; 579 580 /* idr for css->id */ 581 struct idr css_idr; 582 583 /* 584 * List of cftypes. Each entry is the first entry of an array 585 * terminated by zero length name. 586 */ 587 struct list_head cfts; 588 589 /* 590 * Base cftypes which are automatically registered. The two can 591 * point to the same array. 592 */ 593 struct cftype *dfl_cftypes; /* for the default hierarchy */ 594 struct cftype *legacy_cftypes; /* for the legacy hierarchies */ 595 596 /* 597 * A subsystem may depend on other subsystems. When such subsystem 598 * is enabled on a cgroup, the depended-upon subsystems are enabled 599 * together if available. Subsystems enabled due to dependency are 600 * not visible to userland until explicitly enabled. The following 601 * specifies the mask of subsystems that this one depends on. 602 */ 603 unsigned int depends_on; 604}; 605 606extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem; 607 608/** 609 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups 610 * @tsk: target task 611 * 612 * Allows cgroup operations to synchronize against threadgroup changes 613 * using a percpu_rw_semaphore. 614 */ 615static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) 616{ 617 percpu_down_read(&cgroup_threadgroup_rwsem); 618} 619 620/** 621 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups 622 * @tsk: target task 623 * 624 * Counterpart of cgroup_threadcgroup_change_begin(). 625 */ 626static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) 627{ 628 percpu_up_read(&cgroup_threadgroup_rwsem); 629} 630 631#else /* CONFIG_CGROUPS */ 632 633#define CGROUP_SUBSYS_COUNT 0 634 635static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) 636{ 637 might_sleep(); 638} 639 640static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {} 641 642#endif /* CONFIG_CGROUPS */ 643 644#ifdef CONFIG_SOCK_CGROUP_DATA 645 646/* 647 * sock_cgroup_data is embedded at sock->sk_cgrp_data and contains 648 * per-socket cgroup information except for memcg association. 649 * 650 * On legacy hierarchies, net_prio and net_cls controllers directly set 651 * attributes on each sock which can then be tested by the network layer. 652 * On the default hierarchy, each sock is associated with the cgroup it was 653 * created in and the networking layer can match the cgroup directly. 654 * 655 * To avoid carrying all three cgroup related fields separately in sock, 656 * sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer. 657 * On boot, sock_cgroup_data records the cgroup that the sock was created 658 * in so that cgroup2 matches can be made; however, once either net_prio or 659 * net_cls starts being used, the area is overriden to carry prioidx and/or 660 * classid. The two modes are distinguished by whether the lowest bit is 661 * set. Clear bit indicates cgroup pointer while set bit prioidx and 662 * classid. 663 * 664 * While userland may start using net_prio or net_cls at any time, once 665 * either is used, cgroup2 matching no longer works. There is no reason to 666 * mix the two and this is in line with how legacy and v2 compatibility is 667 * handled. On mode switch, cgroup references which are already being 668 * pointed to by socks may be leaked. While this can be remedied by adding 669 * synchronization around sock_cgroup_data, given that the number of leaked 670 * cgroups is bound and highly unlikely to be high, this seems to be the 671 * better trade-off. 672 */ 673struct sock_cgroup_data { 674 union { 675#ifdef __LITTLE_ENDIAN 676 struct { 677 u8 is_data; 678 u8 padding; 679 u16 prioidx; 680 u32 classid; 681 } __packed; 682#else 683 struct { 684 u32 classid; 685 u16 prioidx; 686 u8 padding; 687 u8 is_data; 688 } __packed; 689#endif 690 u64 val; 691 }; 692}; 693 694/* 695 * There's a theoretical window where the following accessors race with 696 * updaters and return part of the previous pointer as the prioidx or 697 * classid. Such races are short-lived and the result isn't critical. 698 */ 699static inline u16 sock_cgroup_prioidx(struct sock_cgroup_data *skcd) 700{ 701 /* fallback to 1 which is always the ID of the root cgroup */ 702 return (skcd->is_data & 1) ? skcd->prioidx : 1; 703} 704 705static inline u32 sock_cgroup_classid(struct sock_cgroup_data *skcd) 706{ 707 /* fallback to 0 which is the unconfigured default classid */ 708 return (skcd->is_data & 1) ? skcd->classid : 0; 709} 710 711/* 712 * If invoked concurrently, the updaters may clobber each other. The 713 * caller is responsible for synchronization. 714 */ 715static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd, 716 u16 prioidx) 717{ 718 struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; 719 720 if (sock_cgroup_prioidx(&skcd_buf) == prioidx) 721 return; 722 723 if (!(skcd_buf.is_data & 1)) { 724 skcd_buf.val = 0; 725 skcd_buf.is_data = 1; 726 } 727 728 skcd_buf.prioidx = prioidx; 729 WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ 730} 731 732static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd, 733 u32 classid) 734{ 735 struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; 736 737 if (sock_cgroup_classid(&skcd_buf) == classid) 738 return; 739 740 if (!(skcd_buf.is_data & 1)) { 741 skcd_buf.val = 0; 742 skcd_buf.is_data = 1; 743 } 744 745 skcd_buf.classid = classid; 746 WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ 747} 748 749#else /* CONFIG_SOCK_CGROUP_DATA */ 750 751struct sock_cgroup_data { 752}; 753 754#endif /* CONFIG_SOCK_CGROUP_DATA */ 755 756#endif /* _LINUX_CGROUP_DEFS_H */ 757