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