include/linux/workqueue.h

   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
  17 struct workqueue_struct;
  18
  19 struct work_struct;
  20 typedef void (*work_func_t)(struct work_struct *work);
  21 void delayed_work_timer_fn(unsigned long __data);
  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
  29 enum {
  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
 101 struct 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
 114 struct 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  */
 128 struct 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
 149 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
 150 {
 151         return container_of(work, struct delayed_work, work);
 152 }
 153
 154 struct 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                                      0, (unsigned long)&(n),            \
 181                                      (tflags) | TIMER_IRQSAFE),         \
 182         }
 183
 184 #define DECLARE_WORK(n, f)                                              \
 185         struct work_struct n = __WORK_INITIALIZER(n, f)
 186
 187 #define DECLARE_DELAYED_WORK(n, f)                                      \
 188         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
 189
 190 #define DECLARE_DEFERRABLE_WORK(n, f)                                   \
 191         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
 192
 193 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 194 extern void __init_work(struct work_struct *work, int onstack);
 195 extern void destroy_work_on_stack(struct work_struct *work);
 196 extern void destroy_delayed_work_on_stack(struct delayed_work *work);
 197 static inline unsigned int work_static(struct work_struct *work)
 198 {
 199         return *work_data_bits(work) & WORK_STRUCT_STATIC;
 200 }
 201 #else
 202 static inline void __init_work(struct work_struct *work, int onstack) { }
 203 static inline void destroy_work_on_stack(struct work_struct *work) { }
 204 static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
 205 static inline unsigned int work_static(struct work_struct *work) { return 0; }
 206 #endif
 207
 208 /*
 209  * initialize all of a work item in one go
 210  *
 211  * NOTE! No point in using "atomic_long_set()": using a direct
 212  * assignment of the work data initializer allows the compiler
 213  * to generate better code.
 214  */
 215 #ifdef CONFIG_LOCKDEP
 216 #define __INIT_WORK(_work, _func, _onstack)                             \
 217         do {                                                            \
 218                 static struct lock_class_key __key;                     \
 219                                                                         \
 220                 __init_work((_work), _onstack);                         \
 221                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 222                 lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
 223                 INIT_LIST_HEAD(&(_work)->entry);                        \
 224                 (_work)->func = (_func);                                \
 225         } while (0)
 226 #else
 227 #define __INIT_WORK(_work, _func, _onstack)                             \
 228         do {                                                            \
 229                 __init_work((_work), _onstack);                         \
 230                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 231                 INIT_LIST_HEAD(&(_work)->entry);                        \
 232                 (_work)->func = (_func);                                \
 233         } while (0)
 234 #endif
 235
 236 #define INIT_WORK(_work, _func)                                         \
 237         __INIT_WORK((_work), (_func), 0)
 238
 239 #define INIT_WORK_ONSTACK(_work, _func)                                 \
 240         __INIT_WORK((_work), (_func), 1)
 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  * @w: The work item in question
 282  */
 283 #define delayed_work_pending(w) \
 284         work_pending(&(w)->work)
 285
 286 /*
 287  * Workqueue flags and constants.  For details, please refer to
 288  * Documentation/core-api/workqueue.rst.
 289  */
 290 enum {
 291         WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
 292         WQ_FREEZABLE            = 1 << 2, /* freeze during suspend */
 293         WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
 294         WQ_HIGHPRI              = 1 << 4, /* high priority */
 295         WQ_CPU_INTENSIVE        = 1 << 5, /* cpu intensive workqueue */
 296         WQ_SYSFS                = 1 << 6, /* visible in sysfs, see wq_sysfs_register() */
 297
 298         /*
 299          * Per-cpu workqueues are generally preferred because they tend to
 300          * show better performance thanks to cache locality.  Per-cpu
 301          * workqueues exclude the scheduler from choosing the CPU to
 302          * execute the worker threads, which has an unfortunate side effect
 303          * of increasing power consumption.
 304          *
 305          * The scheduler considers a CPU idle if it doesn't have any task
 306          * to execute and tries to keep idle cores idle to conserve power;
 307          * however, for example, a per-cpu work item scheduled from an
 308          * interrupt handler on an idle CPU will force the scheduler to
 309          * excute the work item on that CPU breaking the idleness, which in
 310          * turn may lead to more scheduling choices which are sub-optimal
 311          * in terms of power consumption.
 312          *
 313          * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
 314          * but become unbound if workqueue.power_efficient kernel param is
 315          * specified.  Per-cpu workqueues which are identified to
 316          * contribute significantly to power-consumption are identified and
 317          * marked with this flag and enabling the power_efficient mode
 318          * leads to noticeable power saving at the cost of small
 319          * performance disadvantage.
 320          *
 321          * http://thread.gmane.org/gmane.linux.kernel/1480396
 322          */
 323         WQ_POWER_EFFICIENT      = 1 << 7,
 324
 325         __WQ_DRAINING           = 1 << 16, /* internal: workqueue is draining */
 326         __WQ_ORDERED            = 1 << 17, /* internal: workqueue is ordered */
 327         __WQ_LEGACY             = 1 << 18, /* internal: create*_workqueue() */
 328         __WQ_ORDERED_EXPLICIT   = 1 << 19, /* internal: alloc_ordered_workqueue() */
 329
 330         WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
 331         WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
 332         WQ_DFL_ACTIVE           = WQ_MAX_ACTIVE / 2,
 333 };
 334
 335 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
 336 #define WQ_UNBOUND_MAX_ACTIVE   \
 337         max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
 338
 339 /*
 340  * System-wide workqueues which are always present.
 341  *
 342  * system_wq is the one used by schedule[_delayed]_work[_on]().
 343  * Multi-CPU multi-threaded.  There are users which expect relatively
 344  * short queue flush time.  Don't queue works which can run for too
 345  * long.
 346  *
 347  * system_highpri_wq is similar to system_wq but for work items which
 348  * require WQ_HIGHPRI.
 349  *
 350  * system_long_wq is similar to system_wq but may host long running
 351  * works.  Queue flushing might take relatively long.
 352  *
 353  * system_unbound_wq is unbound workqueue.  Workers are not bound to
 354  * any specific CPU, not concurrency managed, and all queued works are
 355  * executed immediately as long as max_active limit is not reached and
 356  * resources are available.
 357  *
 358  * system_freezable_wq is equivalent to system_wq except that it's
 359  * freezable.
 360  *
 361  * *_power_efficient_wq are inclined towards saving power and converted
 362  * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
 363  * they are same as their non-power-efficient counterparts - e.g.
 364  * system_power_efficient_wq is identical to system_wq if
 365  * 'wq_power_efficient' is disabled.  See WQ_POWER_EFFICIENT for more info.
 366  */
 367 extern struct workqueue_struct *system_wq;
 368 extern struct workqueue_struct *system_highpri_wq;
 369 extern struct workqueue_struct *system_long_wq;
 370 extern struct workqueue_struct *system_unbound_wq;
 371 extern struct workqueue_struct *system_freezable_wq;
 372 extern struct workqueue_struct *system_power_efficient_wq;
 373 extern struct workqueue_struct *system_freezable_power_efficient_wq;
 374
 375 extern struct workqueue_struct *
 376 __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
 377         struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
 378
 379 /**
 380  * alloc_workqueue - allocate a workqueue
 381  * @fmt: printf format for the name of the workqueue
 382  * @flags: WQ_* flags
 383  * @max_active: max in-flight work items, 0 for default
 384  * @args...: args for @fmt
 385  *
 386  * Allocate a workqueue with the specified parameters.  For detailed
 387  * information on WQ_* flags, please refer to
 388  * Documentation/core-api/workqueue.rst.
 389  *
 390  * The __lock_name macro dance is to guarantee that single lock_class_key
 391  * doesn't end up with different namesm, which isn't allowed by lockdep.
 392  *
 393  * RETURNS:
 394  * Pointer to the allocated workqueue on success, %NULL on failure.
 395  */
 396 #ifdef CONFIG_LOCKDEP
 397 #define alloc_workqueue(fmt, flags, max_active, args...)                \
 398 ({                                                                      \
 399         static struct lock_class_key __key;                             \
 400         const char *__lock_name;                                        \
 401                                                                         \
 402         __lock_name = #fmt#args;                                        \
 403                                                                         \
 404         __alloc_workqueue_key((fmt), (flags), (max_active),             \
 405                               &__key, __lock_name, ##args);             \
 406 })
 407 #else
 408 #define alloc_workqueue(fmt, flags, max_active, args...)                \
 409         __alloc_workqueue_key((fmt), (flags), (max_active),             \
 410                               NULL, NULL, ##args)
 411 #endif
 412
 413 /**
 414  * alloc_ordered_workqueue - allocate an ordered workqueue
 415  * @fmt: printf format for the name of the workqueue
 416  * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
 417  * @args...: args for @fmt
 418  *
 419  * Allocate an ordered workqueue.  An ordered workqueue executes at
 420  * most one work item at any given time in the queued order.  They are
 421  * implemented as unbound workqueues with @max_active of one.
 422  *
 423  * RETURNS:
 424  * Pointer to the allocated workqueue on success, %NULL on failure.
 425  */
 426 #define alloc_ordered_workqueue(fmt, flags, args...)                    \
 427         alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED |                \
 428                         __WQ_ORDERED_EXPLICIT | (flags), 1, ##args)
 429
 430 #define create_workqueue(name)                                          \
 431         alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name))
 432 #define create_freezable_workqueue(name)                                \
 433         alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \
 434                         WQ_MEM_RECLAIM, 1, (name))
 435 #define create_singlethread_workqueue(name)                             \
 436         alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
 437
 438 extern void destroy_workqueue(struct workqueue_struct *wq);
 439
 440 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
 441 void free_workqueue_attrs(struct workqueue_attrs *attrs);
 442 int apply_workqueue_attrs(struct workqueue_struct *wq,
 443                           const struct workqueue_attrs *attrs);
 444 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
 445
 446 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
 447                         struct work_struct *work);
 448 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 449                         struct delayed_work *work, unsigned long delay);
 450 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
 451                         struct delayed_work *dwork, unsigned long delay);
 452
 453 extern void flush_workqueue(struct workqueue_struct *wq);
 454 extern void drain_workqueue(struct workqueue_struct *wq);
 455
 456 extern int schedule_on_each_cpu(work_func_t func);
 457
 458 int execute_in_process_context(work_func_t fn, struct execute_work *);
 459
 460 extern bool flush_work(struct work_struct *work);
 461 extern bool cancel_work(struct work_struct *work);
 462 extern bool cancel_work_sync(struct work_struct *work);
 463
 464 extern bool flush_delayed_work(struct delayed_work *dwork);
 465 extern bool cancel_delayed_work(struct delayed_work *dwork);
 466 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 467
 468 extern void workqueue_set_max_active(struct workqueue_struct *wq,
 469                                      int max_active);
 470 extern bool current_is_workqueue_rescuer(void);
 471 extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
 472 extern unsigned int work_busy(struct work_struct *work);
 473 extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
 474 extern void print_worker_info(const char *log_lvl, struct task_struct *task);
 475 extern void show_workqueue_state(void);
 476
 477 /**
 478  * queue_work - queue work on a workqueue
 479  * @wq: workqueue to use
 480  * @work: work to queue
 481  *
 482  * Returns %false if @work was already on a queue, %true otherwise.
 483  *
 484  * We queue the work to the CPU on which it was submitted, but if the CPU dies
 485  * it can be processed by another CPU.
 486  */
 487 static inline bool queue_work(struct workqueue_struct *wq,
 488                               struct work_struct *work)
 489 {
 490         return queue_work_on(WORK_CPU_UNBOUND, wq, work);
 491 }
 492
 493 /**
 494  * queue_delayed_work - queue work on a workqueue after delay
 495  * @wq: workqueue to use
 496  * @dwork: delayable work to queue
 497  * @delay: number of jiffies to wait before queueing
 498  *
 499  * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
 500  */
 501 static inline bool queue_delayed_work(struct workqueue_struct *wq,
 502                                       struct delayed_work *dwork,
 503                                       unsigned long delay)
 504 {
 505         return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 506 }
 507
 508 /**
 509  * mod_delayed_work - modify delay of or queue a delayed work
 510  * @wq: workqueue to use
 511  * @dwork: work to queue
 512  * @delay: number of jiffies to wait before queueing
 513  *
 514  * mod_delayed_work_on() on local CPU.
 515  */
 516 static inline bool mod_delayed_work(struct workqueue_struct *wq,
 517                                     struct delayed_work *dwork,
 518                                     unsigned long delay)
 519 {
 520         return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 521 }
 522
 523 /**
 524  * schedule_work_on - put work task on a specific cpu
 525  * @cpu: cpu to put the work task on
 526  * @work: job to be done
 527  *
 528  * This puts a job on a specific cpu
 529  */
 530 static inline bool schedule_work_on(int cpu, struct work_struct *work)
 531 {
 532         return queue_work_on(cpu, system_wq, work);
 533 }
 534
 535 /**
 536  * schedule_work - put work task in global workqueue
 537  * @work: job to be done
 538  *
 539  * Returns %false if @work was already on the kernel-global workqueue and
 540  * %true otherwise.
 541  *
 542  * This puts a job in the kernel-global workqueue if it was not already
 543  * queued and leaves it in the same position on the kernel-global
 544  * workqueue otherwise.
 545  */
 546 static inline bool schedule_work(struct work_struct *work)
 547 {
 548         return queue_work(system_wq, work);
 549 }
 550
 551 /**
 552  * flush_scheduled_work - ensure that any scheduled work has run to completion.
 553  *
 554  * Forces execution of the kernel-global workqueue and blocks until its
 555  * completion.
 556  *
 557  * Think twice before calling this function!  It's very easy to get into
 558  * trouble if you don't take great care.  Either of the following situations
 559  * will lead to deadlock:
 560  *
 561  *      One of the work items currently on the workqueue needs to acquire
 562  *      a lock held by your code or its caller.
 563  *
 564  *      Your code is running in the context of a work routine.
 565  *
 566  * They will be detected by lockdep when they occur, but the first might not
 567  * occur very often.  It depends on what work items are on the workqueue and
 568  * what locks they need, which you have no control over.
 569  *
 570  * In most situations flushing the entire workqueue is overkill; you merely
 571  * need to know that a particular work item isn't queued and isn't running.
 572  * In such cases you should use cancel_delayed_work_sync() or
 573  * cancel_work_sync() instead.
 574  */
 575 static inline void flush_scheduled_work(void)
 576 {
 577         flush_workqueue(system_wq);
 578 }
 579
 580 /**
 581  * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
 582  * @cpu: cpu to use
 583  * @dwork: job to be done
 584  * @delay: number of jiffies to wait
 585  *
 586  * After waiting for a given time this puts a job in the kernel-global
 587  * workqueue on the specified CPU.
 588  */
 589 static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
 590                                             unsigned long delay)
 591 {
 592         return queue_delayed_work_on(cpu, system_wq, dwork, delay);
 593 }
 594
 595 /**
 596  * schedule_delayed_work - put work task in global workqueue after delay
 597  * @dwork: job to be done
 598  * @delay: number of jiffies to wait or 0 for immediate execution
 599  *
 600  * After waiting for a given time this puts a job in the kernel-global
 601  * workqueue.
 602  */
 603 static inline bool schedule_delayed_work(struct delayed_work *dwork,
 604                                          unsigned long delay)
 605 {
 606         return queue_delayed_work(system_wq, dwork, delay);
 607 }
 608
 609 #ifndef CONFIG_SMP
 610 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 611 {
 612         return fn(arg);
 613 }
 614 static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
 615 {
 616         return fn(arg);
 617 }
 618 #else
 619 long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
 620 long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
 621 #endif /* CONFIG_SMP */
 622
 623 #ifdef CONFIG_FREEZER
 624 extern void freeze_workqueues_begin(void);
 625 extern bool freeze_workqueues_busy(void);
 626 extern void thaw_workqueues(void);
 627 #endif /* CONFIG_FREEZER */
 628
 629 #ifdef CONFIG_SYSFS
 630 int workqueue_sysfs_register(struct workqueue_struct *wq);
 631 #else   /* CONFIG_SYSFS */
 632 static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
 633 { return 0; }
 634 #endif  /* CONFIG_SYSFS */
 635
 636 #ifdef CONFIG_WQ_WATCHDOG
 637 void wq_watchdog_touch(int cpu);
 638 #else   /* CONFIG_WQ_WATCHDOG */
 639 static inline void wq_watchdog_touch(int cpu) { }
 640 #endif  /* CONFIG_WQ_WATCHDOG */
 641
 642 #ifdef CONFIG_SMP
 643 int workqueue_prepare_cpu(unsigned int cpu);
 644 int workqueue_online_cpu(unsigned int cpu);
 645 int workqueue_offline_cpu(unsigned int cpu);
 646 #endif
 647
 648 int __init workqueue_init_early(void);
 649 int __init workqueue_init(void);
 650
 651 #endif