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