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        /* special cpu IDs */
  60        WORK_CPU_UNBOUND        = NR_CPUS,
  61        WORK_CPU_END            = NR_CPUS + 1,
  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     = (1 << WORK_OFFQ_FLAG_BASE),
  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(WORK_STRUCT_NO_POOL)
 110#define WORK_DATA_STATIC_INIT() \
 111        ATOMIC_LONG_INIT(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 * A struct for workqueue attributes.  This can be used to change
 124 * attributes of an unbound workqueue.
 125 *
 126 * Unlike other fields, ->no_numa isn't a property of a worker_pool.  It
 127 * only modifies how apply_workqueue_attrs() select pools and thus doesn't
 128 * participate in pool hash calculations or equality comparisons.
 129 */
 130struct workqueue_attrs {
 131        int                     nice;           /* nice level */
 132        cpumask_var_t           cpumask;        /* allowed CPUs */
 133        bool                    no_numa;        /* disable NUMA affinity */
 134};
 135
 136static inline struct delayed_work *to_delayed_work(struct work_struct *work)
 137{
 138        return container_of(work, struct delayed_work, work);
 139}
 140
 141struct execute_work {
 142        struct work_struct work;
 143};
 144
 145#ifdef CONFIG_LOCKDEP
 146/*
 147 * NB: because we have to copy the lockdep_map, setting _key
 148 * here is required, otherwise it could get initialised to the
 149 * copy of the lockdep_map!
 150 */
 151#define __WORK_INIT_LOCKDEP_MAP(n, k) \
 152        .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
 153#else
 154#define __WORK_INIT_LOCKDEP_MAP(n, k)
 155#endif
 156
 157#define __WORK_INITIALIZER(n, f) {                                      \
 158        .data = WORK_DATA_STATIC_INIT(),                                \
 159        .entry  = { &(n).entry, &(n).entry },                           \
 160        .func = (f),                                                    \
 161        __WORK_INIT_LOCKDEP_MAP(#n, &(n))                               \
 162        }
 163
 164#define __DELAYED_WORK_INITIALIZER(n, f, tflags) {                      \
 165        .work = __WORK_INITIALIZER((n).work, (f)),                      \
 166        .timer = __TIMER_INITIALIZER(delayed_work_timer_fn,             \
 167                                     0, (unsigned long)&(n),            \
 168                                     (tflags) | TIMER_IRQSAFE),         \
 169        }
 170
 171#define DECLARE_WORK(n, f)                                              \
 172        struct work_struct n = __WORK_INITIALIZER(n, f)
 173
 174#define DECLARE_DELAYED_WORK(n, f)                                      \
 175        struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
 176
 177#define DECLARE_DEFERRABLE_WORK(n, f)                                   \
 178        struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
 179
 180/*
 181 * initialize a work item's function pointer
 182 */
 183#define PREPARE_WORK(_work, _func)                                      \
 184        do {                                                            \
 185                (_work)->func = (_func);                                \
 186        } while (0)
 187
 188#define PREPARE_DELAYED_WORK(_work, _func)                              \
 189        PREPARE_WORK(&(_work)->work, (_func))
 190
 191#ifdef CONFIG_DEBUG_OBJECTS_WORK
 192extern void __init_work(struct work_struct *work, int onstack);
 193extern void destroy_work_on_stack(struct work_struct *work);
 194static inline unsigned int work_static(struct work_struct *work)
 195{
 196        return *work_data_bits(work) & WORK_STRUCT_STATIC;
 197}
 198#else
 199static inline void __init_work(struct work_struct *work, int onstack) { }
 200static inline void destroy_work_on_stack(struct work_struct *work) { }
 201static inline unsigned int work_static(struct work_struct *work) { return 0; }
 202#endif
 203
 204/*
 205 * initialize all of a work item in one go
 206 *
 207 * NOTE! No point in using "atomic_long_set()": using a direct
 208 * assignment of the work data initializer allows the compiler
 209 * to generate better code.
 210 */
 211#ifdef CONFIG_LOCKDEP
 212#define __INIT_WORK(_work, _func, _onstack)                             \
 213        do {                                                            \
 214                static struct lock_class_key __key;                     \
 215                                                                        \
 216                __init_work((_work), _onstack);                         \
 217                (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 218                lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
 219                INIT_LIST_HEAD(&(_work)->entry);                        \
 220                PREPARE_WORK((_work), (_func));                         \
 221        } while (0)
 222#else
 223#define __INIT_WORK(_work, _func, _onstack)                             \
 224        do {                                                            \
 225                __init_work((_work), _onstack);                         \
 226                (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 227                INIT_LIST_HEAD(&(_work)->entry);                        \
 228                PREPARE_WORK((_work), (_func));                         \
 229        } while (0)
 230#endif
 231
 232#define INIT_WORK(_work, _func)                                         \
 233        do {                                                            \
 234                __INIT_WORK((_work), (_func), 0);                       \
 235        } while (0)
 236
 237#define INIT_WORK_ONSTACK(_work, _func)                                 \
 238        do {                                                            \
 239                __INIT_WORK((_work), (_func), 1);                       \
 240        } while (0)
 241
 242#define __INIT_DELAYED_WORK(_work, _func, _tflags)                      \
 243        do {                                                            \
 244                INIT_WORK(&(_work)->work, (_func));                     \
 245                __setup_timer(&(_work)->timer, delayed_work_timer_fn,   \
 246                              (unsigned long)(_work),                   \
 247                              (_tflags) | TIMER_IRQSAFE);               \
 248        } while (0)
 249
 250#define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)              \
 251        do {                                                            \
 252                INIT_WORK_ONSTACK(&(_work)->work, (_func));             \
 253                __setup_timer_on_stack(&(_work)->timer,                 \
 254                                       delayed_work_timer_fn,           \
 255                                       (unsigned long)(_work),          \
 256                                       (_tflags) | TIMER_IRQSAFE);      \
 257        } while (0)
 258
 259#define INIT_DELAYED_WORK(_work, _func)                                 \
 260        __INIT_DELAYED_WORK(_work, _func, 0)
 261
 262#define INIT_DELAYED_WORK_ONSTACK(_work, _func)                         \
 263        __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
 264
 265#define INIT_DEFERRABLE_WORK(_work, _func)                              \
 266        __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
 267
 268#define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func)                      \
 269        __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
 270
 271/**
 272 * work_pending - Find out whether a work item is currently pending
 273 * @work: The work item in question
 274 */
 275#define work_pending(work) \
 276        test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 277
 278/**
 279 * delayed_work_pending - Find out whether a delayable work item is currently
 280 * pending
 281 * @work: The work item in question
 282 */
 283#define delayed_work_pending(w) \
 284        work_pending(&(w)->work)
 285
 286/**
 287 * work_clear_pending - for internal use only, mark a work item as not pending
 288 * @work: The work item in question
 289 */
 290#define work_clear_pending(work) \
 291        clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 292
 293/*
 294 * Workqueue flags and constants.  For details, please refer to
 295 * Documentation/workqueue.txt.
 296 */
 297enum {
 298        WQ_NON_REENTRANT        = 1 << 0, /* guarantee non-reentrance */
 299        WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
 300        WQ_FREEZABLE            = 1 << 2, /* freeze during suspend */
 301        WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
 302        WQ_HIGHPRI              = 1 << 4, /* high priority */
 303        WQ_CPU_INTENSIVE        = 1 << 5, /* cpu instensive workqueue */
 304        WQ_SYSFS                = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
 305
 306        /*
 307         * Per-cpu workqueues are generally preferred because they tend to
 308         * show better performance thanks to cache locality.  Per-cpu
 309         * workqueues exclude the scheduler from choosing the CPU to
 310         * execute the worker threads, which has an unfortunate side effect
 311         * of increasing power consumption.
 312         *
 313         * The scheduler considers a CPU idle if it doesn't have any task
 314         * to execute and tries to keep idle cores idle to conserve power;
 315         * however, for example, a per-cpu work item scheduled from an
 316         * interrupt handler on an idle CPU will force the scheduler to
 317         * excute the work item on that CPU breaking the idleness, which in
 318         * turn may lead to more scheduling choices which are sub-optimal
 319         * in terms of power consumption.
 320         *
 321         * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
 322         * but become unbound if workqueue.power_efficient kernel param is
 323         * specified.  Per-cpu workqueues which are identified to
 324         * contribute significantly to power-consumption are identified and
 325         * marked with this flag and enabling the power_efficient mode
 326         * leads to noticeable power saving at the cost of small
 327         * performance disadvantage.
 328         *
 329         * http://thread.gmane.org/gmane.linux.kernel/1480396
 330         */
 331        WQ_POWER_EFFICIENT      = 1 << 7,
 332
 333        __WQ_DRAINING           = 1 << 16, /* internal: workqueue is draining */
 334        __WQ_ORDERED            = 1 << 17, /* internal: workqueue is ordered */
 335
 336        WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
 337        WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
 338        WQ_DFL_ACTIVE           = WQ_MAX_ACTIVE / 2,
 339};
 340
 341/* unbound wq's aren't per-cpu, scale max_active according to #cpus */
 342#define WQ_UNBOUND_MAX_ACTIVE   \
 343        max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
 344
 345/*
 346 * System-wide workqueues which are always present.
 347 *
 348 * system_wq is the one used by schedule[_delayed]_work[_on]().
 349 * Multi-CPU multi-threaded.  There are users which expect relatively
 350 * short queue flush time.  Don't queue works which can run for too
 351 * long.
 352 *
 353 * system_long_wq is similar to system_wq but may host long running
 354 * works.  Queue flushing might take relatively long.
 355 *
 356 * system_unbound_wq is unbound workqueue.  Workers are not bound to
 357 * any specific CPU, not concurrency managed, and all queued works are
 358 * executed immediately as long as max_active limit is not reached and
 359 * resources are available.
 360 *
 361 * system_freezable_wq is equivalent to system_wq except that it's
 362 * freezable.
 363 *
 364 * *_power_efficient_wq are inclined towards saving power and converted
 365 * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
 366 * they are same as their non-power-efficient counterparts - e.g.
 367 * system_power_efficient_wq is identical to system_wq if
 368 * 'wq_power_efficient' is disabled.  See WQ_POWER_EFFICIENT for more info.
 369 */
 370extern struct workqueue_struct *system_wq;
 371extern struct workqueue_struct *system_long_wq;
 372extern struct workqueue_struct *system_unbound_wq;
 373extern struct workqueue_struct *system_freezable_wq;
 374extern struct workqueue_struct *system_power_efficient_wq;
 375extern struct workqueue_struct *system_freezable_power_efficient_wq;
 376
 377static inline struct workqueue_struct * __deprecated __system_nrt_wq(void)
 378{
 379        return system_wq;
 380}
 381
 382static inline struct workqueue_struct * __deprecated __system_nrt_freezable_wq(void)
 383{
 384        return system_freezable_wq;
 385}
 386
 387/* equivlalent to system_wq and system_freezable_wq, deprecated */
 388#define system_nrt_wq                   __system_nrt_wq()
 389#define system_nrt_freezable_wq         __system_nrt_freezable_wq()
 390
 391extern struct workqueue_struct *
 392__alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
 393        struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
 394
 395/**
 396 * alloc_workqueue - allocate a workqueue
 397 * @fmt: printf format for the name of the workqueue
 398 * @flags: WQ_* flags
 399 * @max_active: max in-flight work items, 0 for default
 400 * @args: args for @fmt
 401 *
 402 * Allocate a workqueue with the specified parameters.  For detailed
 403 * information on WQ_* flags, please refer to Documentation/workqueue.txt.
 404 *
 405 * The __lock_name macro dance is to guarantee that single lock_class_key
 406 * doesn't end up with different namesm, which isn't allowed by lockdep.
 407 *
 408 * RETURNS:
 409 * Pointer to the allocated workqueue on success, %NULL on failure.
 410 */
 411#ifdef CONFIG_LOCKDEP
 412#define alloc_workqueue(fmt, flags, max_active, args...)                \
 413({                                                                      \
 414        static struct lock_class_key __key;                             \
 415        const char *__lock_name;                                        \
 416                                                                        \
 417        if (__builtin_constant_p(fmt))                                  \
 418                __lock_name = (fmt);                                    \
 419        else                                                            \
 420                __lock_name = #fmt;                                     \
 421                                                                        \
 422        __alloc_workqueue_key((fmt), (flags), (max_active),             \
 423                              &__key, __lock_name, ##args);             \
 424})
 425#else
 426#define alloc_workqueue(fmt, flags, max_active, args...)                \
 427        __alloc_workqueue_key((fmt), (flags), (max_active),             \
 428                              NULL, NULL, ##args)
 429#endif
 430
 431/**
 432 * alloc_ordered_workqueue - allocate an ordered workqueue
 433 * @fmt: printf format for the name of the workqueue
 434 * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
 435 * @args: args for @fmt
 436 *
 437 * Allocate an ordered workqueue.  An ordered workqueue executes at
 438 * most one work item at any given time in the queued order.  They are
 439 * implemented as unbound workqueues with @max_active of one.
 440 *
 441 * RETURNS:
 442 * Pointer to the allocated workqueue on success, %NULL on failure.
 443 */
 444#define alloc_ordered_workqueue(fmt, flags, args...)                    \
 445        alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args)
 446
 447#define create_workqueue(name)                                          \
 448        alloc_workqueue("%s", WQ_MEM_RECLAIM, 1, (name))
 449#define create_freezable_workqueue(name)                                \
 450        alloc_workqueue("%s", WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, \
 451                        1, (name))
 452#define create_singlethread_workqueue(name)                             \
 453        alloc_workqueue("%s", WQ_UNBOUND | WQ_MEM_RECLAIM, 1, (name))
 454
 455extern void destroy_workqueue(struct workqueue_struct *wq);
 456
 457struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
 458void free_workqueue_attrs(struct workqueue_attrs *attrs);
 459int apply_workqueue_attrs(struct workqueue_struct *wq,
 460                          const struct workqueue_attrs *attrs);
 461
 462extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
 463                        struct work_struct *work);
 464extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 465                        struct delayed_work *work, unsigned long delay);
 466extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
 467                        struct delayed_work *dwork, unsigned long delay);
 468
 469extern void flush_workqueue(struct workqueue_struct *wq);
 470extern void drain_workqueue(struct workqueue_struct *wq);
 471extern void flush_scheduled_work(void);
 472
 473extern int schedule_on_each_cpu(work_func_t func);
 474
 475int execute_in_process_context(work_func_t fn, struct execute_work *);
 476
 477extern bool flush_work(struct work_struct *work);
 478extern bool cancel_work_sync(struct work_struct *work);
 479
 480extern bool flush_delayed_work(struct delayed_work *dwork);
 481extern bool cancel_delayed_work(struct delayed_work *dwork);
 482extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 483
 484extern void workqueue_set_max_active(struct workqueue_struct *wq,
 485                                     int max_active);
 486extern bool current_is_workqueue_rescuer(void);
 487extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
 488extern unsigned int work_busy(struct work_struct *work);
 489extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
 490extern void print_worker_info(const char *log_lvl, struct task_struct *task);
 491
 492/**
 493 * queue_work - queue work on a workqueue
 494 * @wq: workqueue to use
 495 * @work: work to queue
 496 *
 497 * Returns %false if @work was already on a queue, %true otherwise.
 498 *
 499 * We queue the work to the CPU on which it was submitted, but if the CPU dies
 500 * it can be processed by another CPU.
 501 */
 502static inline bool queue_work(struct workqueue_struct *wq,
 503                              struct work_struct *work)
 504{
 505        return queue_work_on(WORK_CPU_UNBOUND, wq, work);
 506}
 507
 508/**
 509 * queue_delayed_work - queue work on a workqueue after delay
 510 * @wq: workqueue to use
 511 * @dwork: delayable work to queue
 512 * @delay: number of jiffies to wait before queueing
 513 *
 514 * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
 515 */
 516static inline bool queue_delayed_work(struct workqueue_struct *wq,
 517                                      struct delayed_work *dwork,
 518                                      unsigned long delay)
 519{
 520        return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 521}
 522
 523/**
 524 * mod_delayed_work - modify delay of or queue a delayed work
 525 * @wq: workqueue to use
 526 * @dwork: work to queue
 527 * @delay: number of jiffies to wait before queueing
 528 *
 529 * mod_delayed_work_on() on local CPU.
 530 */
 531static inline bool mod_delayed_work(struct workqueue_struct *wq,
 532                                    struct delayed_work *dwork,
 533                                    unsigned long delay)
 534{
 535        return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 536}
 537
 538/**
 539 * schedule_work_on - put work task on a specific cpu
 540 * @cpu: cpu to put the work task on
 541 * @work: job to be done
 542 *
 543 * This puts a job on a specific cpu
 544 */
 545static inline bool schedule_work_on(int cpu, struct work_struct *work)
 546{
 547        return queue_work_on(cpu, system_wq, work);
 548}
 549
 550/**
 551 * schedule_work - put work task in global workqueue
 552 * @work: job to be done
 553 *
 554 * Returns %false if @work was already on the kernel-global workqueue and
 555 * %true otherwise.
 556 *
 557 * This puts a job in the kernel-global workqueue if it was not already
 558 * queued and leaves it in the same position on the kernel-global
 559 * workqueue otherwise.
 560 */
 561static inline bool schedule_work(struct work_struct *work)
 562{
 563        return queue_work(system_wq, work);
 564}
 565
 566/**
 567 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
 568 * @cpu: cpu to use
 569 * @dwork: job to be done
 570 * @delay: number of jiffies to wait
 571 *
 572 * After waiting for a given time this puts a job in the kernel-global
 573 * workqueue on the specified CPU.
 574 */
 575static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
 576                                            unsigned long delay)
 577{
 578        return queue_delayed_work_on(cpu, system_wq, dwork, delay);
 579}
 580
 581/**
 582 * schedule_delayed_work - put work task in global workqueue after delay
 583 * @dwork: job to be done
 584 * @delay: number of jiffies to wait or 0 for immediate execution
 585 *
 586 * After waiting for a given time this puts a job in the kernel-global
 587 * workqueue.
 588 */
 589static inline bool schedule_delayed_work(struct delayed_work *dwork,
 590                                         unsigned long delay)
 591{
 592        return queue_delayed_work(system_wq, dwork, delay);
 593}
 594
 595/**
 596 * keventd_up - is workqueue initialized yet?
 597 */
 598static inline bool keventd_up(void)
 599{
 600        return system_wq != NULL;
 601}
 602
 603/*
 604 * Like above, but uses del_timer() instead of del_timer_sync(). This means,
 605 * if it returns 0 the timer function may be running and the queueing is in
 606 * progress.
 607 */
 608static inline bool __deprecated __cancel_delayed_work(struct delayed_work *work)
 609{
 610        bool ret;
 611
 612        ret = del_timer(&work->timer);
 613        if (ret)
 614                work_clear_pending(&work->work);
 615        return ret;
 616}
 617
 618/* used to be different but now identical to flush_work(), deprecated */
 619static inline bool __deprecated flush_work_sync(struct work_struct *work)
 620{
 621        return flush_work(work);
 622}
 623
 624/* used to be different but now identical to flush_delayed_work(), deprecated */
 625static inline bool __deprecated flush_delayed_work_sync(struct delayed_work *dwork)
 626{
 627        return flush_delayed_work(dwork);
 628}
 629
 630#ifndef CONFIG_SMP
 631static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 632{
 633        return fn(arg);
 634}
 635#else
 636long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
 637#endif /* CONFIG_SMP */
 638
 639#ifdef CONFIG_FREEZER
 640extern void freeze_workqueues_begin(void);
 641extern bool freeze_workqueues_busy(void);
 642extern void thaw_workqueues(void);
 643#endif /* CONFIG_FREEZER */
 644
 645#ifdef CONFIG_SYSFS
 646int workqueue_sysfs_register(struct workqueue_struct *wq);
 647#else   /* CONFIG_SYSFS */
 648static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
 649{ return 0; }
 650#endif  /* CONFIG_SYSFS */
 651
 652#endif
 653