linux/include/linux/workqueue.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * workqueue.h --- work queue handling for Linux.
   4 */
   5
   6#ifndef _LINUX_WORKQUEUE_H
   7#define _LINUX_WORKQUEUE_H
   8
   9#include <linux/timer.h>
  10#include <linux/linkage.h>
  11#include <linux/bitops.h>
  12#include <linux/lockdep.h>
  13#include <linux/threads.h>
  14#include <linux/atomic.h>
  15#include <linux/cpumask.h>
  16#include <linux/rcupdate.h>
  17
  18struct workqueue_struct;
  19
  20struct work_struct;
  21typedef void (*work_func_t)(struct work_struct *work);
  22void delayed_work_timer_fn(struct timer_list *t);
  23
  24/*
  25 * The first word is the work queue pointer and the flags rolled into
  26 * one
  27 */
  28#define work_data_bits(work) ((unsigned long *)(&(work)->data))
  29
  30enum {
  31        WORK_STRUCT_PENDING_BIT = 0,    /* work item is pending execution */
  32        WORK_STRUCT_DELAYED_BIT = 1,    /* work item is delayed */
  33        WORK_STRUCT_PWQ_BIT     = 2,    /* data points to pwq */
  34        WORK_STRUCT_LINKED_BIT  = 3,    /* next work is linked to this one */
  35#ifdef CONFIG_DEBUG_OBJECTS_WORK
  36        WORK_STRUCT_STATIC_BIT  = 4,    /* static initializer (debugobjects) */
  37        WORK_STRUCT_COLOR_SHIFT = 5,    /* color for workqueue flushing */
  38#else
  39        WORK_STRUCT_COLOR_SHIFT = 4,    /* color for workqueue flushing */
  40#endif
  41
  42        WORK_STRUCT_COLOR_BITS  = 4,
  43
  44        WORK_STRUCT_PENDING     = 1 << WORK_STRUCT_PENDING_BIT,
  45        WORK_STRUCT_DELAYED     = 1 << WORK_STRUCT_DELAYED_BIT,
  46        WORK_STRUCT_PWQ         = 1 << WORK_STRUCT_PWQ_BIT,
  47        WORK_STRUCT_LINKED      = 1 << WORK_STRUCT_LINKED_BIT,
  48#ifdef CONFIG_DEBUG_OBJECTS_WORK
  49        WORK_STRUCT_STATIC      = 1 << WORK_STRUCT_STATIC_BIT,
  50#else
  51        WORK_STRUCT_STATIC      = 0,
  52#endif
  53
  54        /*
  55         * The last color is no color used for works which don't
  56         * participate in workqueue flushing.
  57         */
  58        WORK_NR_COLORS          = (1 << WORK_STRUCT_COLOR_BITS) - 1,
  59        WORK_NO_COLOR           = WORK_NR_COLORS,
  60
  61        /* not bound to any CPU, prefer the local CPU */
  62        WORK_CPU_UNBOUND        = NR_CPUS,
  63
  64        /*
  65         * Reserve 7 bits off of pwq pointer w/ debugobjects turned off.
  66         * This makes pwqs aligned to 256 bytes and allows 15 workqueue
  67         * flush colors.
  68         */
  69        WORK_STRUCT_FLAG_BITS   = WORK_STRUCT_COLOR_SHIFT +
  70                                  WORK_STRUCT_COLOR_BITS,
  71
  72        /* data contains off-queue information when !WORK_STRUCT_PWQ */
  73        WORK_OFFQ_FLAG_BASE     = WORK_STRUCT_COLOR_SHIFT,
  74
  75        __WORK_OFFQ_CANCELING   = WORK_OFFQ_FLAG_BASE,
  76        WORK_OFFQ_CANCELING     = (1 << __WORK_OFFQ_CANCELING),
  77
  78        /*
  79         * When a work item is off queue, its high bits point to the last
  80         * pool it was on.  Cap at 31 bits and use the highest number to
  81         * indicate that no pool is associated.
  82         */
  83        WORK_OFFQ_FLAG_BITS     = 1,
  84        WORK_OFFQ_POOL_SHIFT    = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
  85        WORK_OFFQ_LEFT          = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
  86        WORK_OFFQ_POOL_BITS     = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
  87        WORK_OFFQ_POOL_NONE     = (1LU << WORK_OFFQ_POOL_BITS) - 1,
  88
  89        /* convenience constants */
  90        WORK_STRUCT_FLAG_MASK   = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
  91        WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
  92        WORK_STRUCT_NO_POOL     = (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
  93
  94        /* bit mask for work_busy() return values */
  95        WORK_BUSY_PENDING       = 1 << 0,
  96        WORK_BUSY_RUNNING       = 1 << 1,
  97
  98        /* maximum string length for set_worker_desc() */
  99        WORKER_DESC_LEN         = 24,
 100};
 101
 102struct work_struct {
 103        atomic_long_t data;
 104        struct list_head entry;
 105        work_func_t func;
 106#ifdef CONFIG_LOCKDEP
 107        struct lockdep_map lockdep_map;
 108#endif
 109};
 110
 111#define WORK_DATA_INIT()        ATOMIC_LONG_INIT((unsigned long)WORK_STRUCT_NO_POOL)
 112#define WORK_DATA_STATIC_INIT() \
 113        ATOMIC_LONG_INIT((unsigned long)(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC))
 114
 115struct delayed_work {
 116        struct work_struct work;
 117        struct timer_list timer;
 118
 119        /* target workqueue and CPU ->timer uses to queue ->work */
 120        struct workqueue_struct *wq;
 121        int cpu;
 122};
 123
 124struct rcu_work {
 125        struct work_struct work;
 126        struct rcu_head rcu;
 127
 128        /* target workqueue ->rcu uses to queue ->work */
 129        struct workqueue_struct *wq;
 130};
 131
 132/**
 133 * struct workqueue_attrs - A struct for workqueue attributes.
 134 *
 135 * This can be used to change attributes of an unbound workqueue.
 136 */
 137struct workqueue_attrs {
 138        /**
 139         * @nice: nice level
 140         */
 141        int nice;
 142
 143        /**
 144         * @cpumask: allowed CPUs
 145         */
 146        cpumask_var_t cpumask;
 147
 148        /**
 149         * @no_numa: disable NUMA affinity
 150         *
 151         * Unlike other fields, ``no_numa`` isn't a property of a worker_pool. It
 152         * only modifies how :c:func:`apply_workqueue_attrs` select pools and thus
 153         * doesn't participate in pool hash calculations or equality comparisons.
 154         */
 155        bool no_numa;
 156};
 157
 158static inline struct delayed_work *to_delayed_work(struct work_struct *work)
 159{
 160        return container_of(work, struct delayed_work, work);
 161}
 162
 163static inline struct rcu_work *to_rcu_work(struct work_struct *work)
 164{
 165        return container_of(work, struct rcu_work, work);
 166}
 167
 168struct execute_work {
 169        struct work_struct work;
 170};
 171
 172#ifdef CONFIG_LOCKDEP
 173/*
 174 * NB: because we have to copy the lockdep_map, setting _key
 175 * here is required, otherwise it could get initialised to the
 176 * copy of the lockdep_map!
 177 */
 178#define __WORK_INIT_LOCKDEP_MAP(n, k) \
 179        .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
 180#else
 181#define __WORK_INIT_LOCKDEP_MAP(n, k)
 182#endif
 183
 184#define __WORK_INITIALIZER(n, f) {                                      \
 185        .data = WORK_DATA_STATIC_INIT(),                                \
 186        .entry  = { &(n).entry, &(n).entry },                           \
 187        .func = (f),                                                    \
 188        __WORK_INIT_LOCKDEP_MAP(#n, &(n))                               \
 189        }
 190
 191#define __DELAYED_WORK_INITIALIZER(n, f, tflags) {                      \
 192        .work = __WORK_INITIALIZER((n).work, (f)),                      \
 193        .timer = __TIMER_INITIALIZER(delayed_work_timer_fn,\
 194                                     (tflags) | TIMER_IRQSAFE),         \
 195        }
 196
 197#define DECLARE_WORK(n, f)                                              \
 198        struct work_struct n = __WORK_INITIALIZER(n, f)
 199
 200#define DECLARE_DELAYED_WORK(n, f)                                      \
 201        struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
 202
 203#define DECLARE_DEFERRABLE_WORK(n, f)                                   \
 204        struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
 205
 206#ifdef CONFIG_DEBUG_OBJECTS_WORK
 207extern void __init_work(struct work_struct *work, int onstack);
 208extern void destroy_work_on_stack(struct work_struct *work);
 209extern void destroy_delayed_work_on_stack(struct delayed_work *work);
 210static inline unsigned int work_static(struct work_struct *work)
 211{
 212        return *work_data_bits(work) & WORK_STRUCT_STATIC;
 213}
 214#else
 215static inline void __init_work(struct work_struct *work, int onstack) { }
 216static inline void destroy_work_on_stack(struct work_struct *work) { }
 217static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
 218static inline unsigned int work_static(struct work_struct *work) { return 0; }
 219#endif
 220
 221/*
 222 * initialize all of a work item in one go
 223 *
 224 * NOTE! No point in using "atomic_long_set()": using a direct
 225 * assignment of the work data initializer allows the compiler
 226 * to generate better code.
 227 */
 228#ifdef CONFIG_LOCKDEP
 229#define __INIT_WORK(_work, _func, _onstack)                             \
 230        do {                                                            \
 231                static struct lock_class_key __key;                     \
 232                                                                        \
 233                __init_work((_work), _onstack);                         \
 234                (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 235                lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, &__key, 0); \
 236                INIT_LIST_HEAD(&(_work)->entry);                        \
 237                (_work)->func = (_func);                                \
 238        } while (0)
 239#else
 240#define __INIT_WORK(_work, _func, _onstack)                             \
 241        do {                                                            \
 242                __init_work((_work), _onstack);                         \
 243                (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 244                INIT_LIST_HEAD(&(_work)->entry);                        \
 245                (_work)->func = (_func);                                \
 246        } while (0)
 247#endif
 248
 249#define INIT_WORK(_work, _func)                                         \
 250        __INIT_WORK((_work), (_func), 0)
 251
 252#define INIT_WORK_ONSTACK(_work, _func)                                 \
 253        __INIT_WORK((_work), (_func), 1)
 254
 255#define __INIT_DELAYED_WORK(_work, _func, _tflags)                      \
 256        do {                                                            \
 257                INIT_WORK(&(_work)->work, (_func));                     \
 258                __init_timer(&(_work)->timer,                           \
 259                             delayed_work_timer_fn,                     \
 260                             (_tflags) | TIMER_IRQSAFE);                \
 261        } while (0)
 262
 263#define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)              \
 264        do {                                                            \
 265                INIT_WORK_ONSTACK(&(_work)->work, (_func));             \
 266                __init_timer_on_stack(&(_work)->timer,                  \
 267                                      delayed_work_timer_fn,            \
 268                                      (_tflags) | TIMER_IRQSAFE);       \
 269        } while (0)
 270
 271#define INIT_DELAYED_WORK(_work, _func)                                 \
 272        __INIT_DELAYED_WORK(_work, _func, 0)
 273
 274#define INIT_DELAYED_WORK_ONSTACK(_work, _func)                         \
 275        __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
 276
 277#define INIT_DEFERRABLE_WORK(_work, _func)                              \
 278        __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
 279
 280#define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func)                      \
 281        __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
 282
 283#define INIT_RCU_WORK(_work, _func)                                     \
 284        INIT_WORK(&(_work)->work, (_func))
 285
 286#define INIT_RCU_WORK_ONSTACK(_work, _func)                             \
 287        INIT_WORK_ONSTACK(&(_work)->work, (_func))
 288
 289/**
 290 * work_pending - Find out whether a work item is currently pending
 291 * @work: The work item in question
 292 */
 293#define work_pending(work) \
 294        test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 295
 296/**
 297 * delayed_work_pending - Find out whether a delayable work item is currently
 298 * pending
 299 * @w: The work item in question
 300 */
 301#define delayed_work_pending(w) \
 302        work_pending(&(w)->work)
 303
 304/*
 305 * Workqueue flags and constants.  For details, please refer to
 306 * Documentation/core-api/workqueue.rst.
 307 */
 308enum {
 309        WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
 310        WQ_FREEZABLE            = 1 << 2, /* freeze during suspend */
 311        WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
 312        WQ_HIGHPRI              = 1 << 4, /* high priority */
 313        WQ_CPU_INTENSIVE        = 1 << 5, /* cpu intensive workqueue */
 314        WQ_SYSFS                = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
 315
 316        /*
 317         * Per-cpu workqueues are generally preferred because they tend to
 318         * show better performance thanks to cache locality.  Per-cpu
 319         * workqueues exclude the scheduler from choosing the CPU to
 320         * execute the worker threads, which has an unfortunate side effect
 321         * of increasing power consumption.
 322         *
 323         * The scheduler considers a CPU idle if it doesn't have any task
 324         * to execute and tries to keep idle cores idle to conserve power;
 325         * however, for example, a per-cpu work item scheduled from an
 326         * interrupt handler on an idle CPU will force the scheduler to
 327         * excute the work item on that CPU breaking the idleness, which in
 328         * turn may lead to more scheduling choices which are sub-optimal
 329         * in terms of power consumption.
 330         *
 331         * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
 332         * but become unbound if workqueue.power_efficient kernel param is
 333         * specified.  Per-cpu workqueues which are identified to
 334         * contribute significantly to power-consumption are identified and
 335         * marked with this flag and enabling the power_efficient mode
 336         * leads to noticeable power saving at the cost of small
 337         * performance disadvantage.
 338         *
 339         * http://thread.gmane.org/gmane.linux.kernel/1480396
 340         */
 341        WQ_POWER_EFFICIENT      = 1 << 7,
 342
 343        __WQ_DRAINING           = 1 << 16, /* internal: workqueue is draining */
 344        __WQ_ORDERED            = 1 << 17, /* internal: workqueue is ordered */
 345        __WQ_LEGACY             = 1 << 18, /* internal: create*_workqueue() */
 346        __WQ_ORDERED_EXPLICIT   = 1 << 19, /* internal: alloc_ordered_workqueue() */
 347
 348        WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
 349        WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
 350        WQ_DFL_ACTIVE           = WQ_MAX_ACTIVE / 2,
 351};
 352
 353/* unbound wq's aren't per-cpu, scale max_active according to #cpus */
 354#define WQ_UNBOUND_MAX_ACTIVE   \
 355        max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
 356
 357/*
 358 * System-wide workqueues which are always present.
 359 *
 360 * system_wq is the one used by schedule[_delayed]_work[_on]().
 361 * Multi-CPU multi-threaded.  There are users which expect relatively
 362 * short queue flush time.  Don't queue works which can run for too
 363 * long.
 364 *
 365 * system_highpri_wq is similar to system_wq but for work items which
 366 * require WQ_HIGHPRI.
 367 *
 368 * system_long_wq is similar to system_wq but may host long running
 369 * works.  Queue flushing might take relatively long.
 370 *
 371 * system_unbound_wq is unbound workqueue.  Workers are not bound to
 372 * any specific CPU, not concurrency managed, and all queued works are
 373 * executed immediately as long as max_active limit is not reached and
 374 * resources are available.
 375 *
 376 * system_freezable_wq is equivalent to system_wq except that it's
 377 * freezable.
 378 *
 379 * *_power_efficient_wq are inclined towards saving power and converted
 380 * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
 381 * they are same as their non-power-efficient counterparts - e.g.
 382 * system_power_efficient_wq is identical to system_wq if
 383 * 'wq_power_efficient' is disabled.  See WQ_POWER_EFFICIENT for more info.
 384 */
 385extern struct workqueue_struct *system_wq;
 386extern struct workqueue_struct *system_highpri_wq;
 387extern struct workqueue_struct *system_long_wq;
 388extern struct workqueue_struct *system_unbound_wq;
 389extern struct workqueue_struct *system_freezable_wq;
 390extern struct workqueue_struct *system_power_efficient_wq;
 391extern struct workqueue_struct *system_freezable_power_efficient_wq;
 392
 393/**
 394 * alloc_workqueue - allocate a workqueue
 395 * @fmt: printf format for the name of the workqueue
 396 * @flags: WQ_* flags
 397 * @max_active: max in-flight work items, 0 for default
 398 * remaining args: args for @fmt
 399 *
 400 * Allocate a workqueue with the specified parameters.  For detailed
 401 * information on WQ_* flags, please refer to
 402 * Documentation/core-api/workqueue.rst.
 403 *
 404 * RETURNS:
 405 * Pointer to the allocated workqueue on success, %NULL on failure.
 406 */
 407struct workqueue_struct *alloc_workqueue(const char *fmt,
 408                                         unsigned int flags,
 409                                         int max_active, ...);
 410
 411/**
 412 * alloc_ordered_workqueue - allocate an ordered workqueue
 413 * @fmt: printf format for the name of the workqueue
 414 * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
 415 * @args...: args for @fmt
 416 *
 417 * Allocate an ordered workqueue.  An ordered workqueue executes at
 418 * most one work item at any given time in the queued order.  They are
 419 * implemented as unbound workqueues with @max_active of one.
 420 *
 421 * RETURNS:
 422 * Pointer to the allocated workqueue on success, %NULL on failure.
 423 */
 424#define alloc_ordered_workqueue(fmt, flags, args...)                    \
 425        alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED |                \
 426                        __WQ_ORDERED_EXPLICIT | (flags), 1, ##args)
 427
 428#define create_workqueue(name)                                          \
 429        alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name))
 430#define create_freezable_workqueue(name)                                \
 431        alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \
 432                        WQ_MEM_RECLAIM, 1, (name))
 433#define create_singlethread_workqueue(name)                             \
 434        alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
 435
 436extern void destroy_workqueue(struct workqueue_struct *wq);
 437
 438struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
 439void free_workqueue_attrs(struct workqueue_attrs *attrs);
 440int apply_workqueue_attrs(struct workqueue_struct *wq,
 441                          const struct workqueue_attrs *attrs);
 442int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
 443
 444extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
 445                        struct work_struct *work);
 446extern bool queue_work_node(int node, struct workqueue_struct *wq,
 447                            struct work_struct *work);
 448extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 449                        struct delayed_work *work, unsigned long delay);
 450extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
 451                        struct delayed_work *dwork, unsigned long delay);
 452extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork);
 453
 454extern void flush_workqueue(struct workqueue_struct *wq);
 455extern void drain_workqueue(struct workqueue_struct *wq);
 456
 457extern int schedule_on_each_cpu(work_func_t func);
 458
 459int execute_in_process_context(work_func_t fn, struct execute_work *);
 460
 461extern bool flush_work(struct work_struct *work);
 462extern bool cancel_work_sync(struct work_struct *work);
 463
 464extern bool flush_delayed_work(struct delayed_work *dwork);
 465extern bool cancel_delayed_work(struct delayed_work *dwork);
 466extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 467
 468extern bool flush_rcu_work(struct rcu_work *rwork);
 469
 470extern void workqueue_set_max_active(struct workqueue_struct *wq,
 471                                     int max_active);
 472extern struct work_struct *current_work(void);
 473extern bool current_is_workqueue_rescuer(void);
 474extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
 475extern unsigned int work_busy(struct work_struct *work);
 476extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
 477extern void print_worker_info(const char *log_lvl, struct task_struct *task);
 478extern void show_workqueue_state(void);
 479extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task);
 480
 481/**
 482 * queue_work - queue work on a workqueue
 483 * @wq: workqueue to use
 484 * @work: work to queue
 485 *
 486 * Returns %false if @work was already on a queue, %true otherwise.
 487 *
 488 * We queue the work to the CPU on which it was submitted, but if the CPU dies
 489 * it can be processed by another CPU.
 490 */
 491static inline bool queue_work(struct workqueue_struct *wq,
 492                              struct work_struct *work)
 493{
 494        return queue_work_on(WORK_CPU_UNBOUND, wq, work);
 495}
 496
 497/**
 498 * queue_delayed_work - queue work on a workqueue after delay
 499 * @wq: workqueue to use
 500 * @dwork: delayable work to queue
 501 * @delay: number of jiffies to wait before queueing
 502 *
 503 * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
 504 */
 505static inline bool queue_delayed_work(struct workqueue_struct *wq,
 506                                      struct delayed_work *dwork,
 507                                      unsigned long delay)
 508{
 509        return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 510}
 511
 512/**
 513 * mod_delayed_work - modify delay of or queue a delayed work
 514 * @wq: workqueue to use
 515 * @dwork: work to queue
 516 * @delay: number of jiffies to wait before queueing
 517 *
 518 * mod_delayed_work_on() on local CPU.
 519 */
 520static inline bool mod_delayed_work(struct workqueue_struct *wq,
 521                                    struct delayed_work *dwork,
 522                                    unsigned long delay)
 523{
 524        return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 525}
 526
 527/**
 528 * schedule_work_on - put work task on a specific cpu
 529 * @cpu: cpu to put the work task on
 530 * @work: job to be done
 531 *
 532 * This puts a job on a specific cpu
 533 */
 534static inline bool schedule_work_on(int cpu, struct work_struct *work)
 535{
 536        return queue_work_on(cpu, system_wq, work);
 537}
 538
 539/**
 540 * schedule_work - put work task in global workqueue
 541 * @work: job to be done
 542 *
 543 * Returns %false if @work was already on the kernel-global workqueue and
 544 * %true otherwise.
 545 *
 546 * This puts a job in the kernel-global workqueue if it was not already
 547 * queued and leaves it in the same position on the kernel-global
 548 * workqueue otherwise.
 549 */
 550static inline bool schedule_work(struct work_struct *work)
 551{
 552        return queue_work(system_wq, work);
 553}
 554
 555/**
 556 * flush_scheduled_work - ensure that any scheduled work has run to completion.
 557 *
 558 * Forces execution of the kernel-global workqueue and blocks until its
 559 * completion.
 560 *
 561 * Think twice before calling this function!  It's very easy to get into
 562 * trouble if you don't take great care.  Either of the following situations
 563 * will lead to deadlock:
 564 *
 565 *      One of the work items currently on the workqueue needs to acquire
 566 *      a lock held by your code or its caller.
 567 *
 568 *      Your code is running in the context of a work routine.
 569 *
 570 * They will be detected by lockdep when they occur, but the first might not
 571 * occur very often.  It depends on what work items are on the workqueue and
 572 * what locks they need, which you have no control over.
 573 *
 574 * In most situations flushing the entire workqueue is overkill; you merely
 575 * need to know that a particular work item isn't queued and isn't running.
 576 * In such cases you should use cancel_delayed_work_sync() or
 577 * cancel_work_sync() instead.
 578 */
 579static inline void flush_scheduled_work(void)
 580{
 581        flush_workqueue(system_wq);
 582}
 583
 584/**
 585 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
 586 * @cpu: cpu to use
 587 * @dwork: job to be done
 588 * @delay: number of jiffies to wait
 589 *
 590 * After waiting for a given time this puts a job in the kernel-global
 591 * workqueue on the specified CPU.
 592 */
 593static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
 594                                            unsigned long delay)
 595{
 596        return queue_delayed_work_on(cpu, system_wq, dwork, delay);
 597}
 598
 599/**
 600 * schedule_delayed_work - put work task in global workqueue after delay
 601 * @dwork: job to be done
 602 * @delay: number of jiffies to wait or 0 for immediate execution
 603 *
 604 * After waiting for a given time this puts a job in the kernel-global
 605 * workqueue.
 606 */
 607static inline bool schedule_delayed_work(struct delayed_work *dwork,
 608                                         unsigned long delay)
 609{
 610        return queue_delayed_work(system_wq, dwork, delay);
 611}
 612
 613#ifndef CONFIG_SMP
 614static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 615{
 616        return fn(arg);
 617}
 618static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
 619{
 620        return fn(arg);
 621}
 622#else
 623long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
 624long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
 625#endif /* CONFIG_SMP */
 626
 627#ifdef CONFIG_FREEZER
 628extern void freeze_workqueues_begin(void);
 629extern bool freeze_workqueues_busy(void);
 630extern void thaw_workqueues(void);
 631#endif /* CONFIG_FREEZER */
 632
 633#ifdef CONFIG_SYSFS
 634int workqueue_sysfs_register(struct workqueue_struct *wq);
 635#else   /* CONFIG_SYSFS */
 636static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
 637{ return 0; }
 638#endif  /* CONFIG_SYSFS */
 639
 640#ifdef CONFIG_WQ_WATCHDOG
 641void wq_watchdog_touch(int cpu);
 642#else   /* CONFIG_WQ_WATCHDOG */
 643static inline void wq_watchdog_touch(int cpu) { }
 644#endif  /* CONFIG_WQ_WATCHDOG */
 645
 646#ifdef CONFIG_SMP
 647int workqueue_prepare_cpu(unsigned int cpu);
 648int workqueue_online_cpu(unsigned int cpu);
 649int workqueue_offline_cpu(unsigned int cpu);
 650#endif
 651
 652int __init workqueue_init_early(void);
 653int __init workqueue_init(void);
 654
 655#endif
 656