include/linux/workqueue.h

   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
  16 struct workqueue_struct;
  17
  18 struct work_struct;
  19 typedef void (*work_func_t)(struct work_struct *work);
  20 void 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
  28 enum {
  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
 100 struct 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
 113 struct 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  */
 127 struct 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
 148 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
 149 {
 150         return container_of(work, struct delayed_work, work);
 151 }
 152
 153 struct 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
 193 extern void __init_work(struct work_struct *work, int onstack);
 194 extern void destroy_work_on_stack(struct work_struct *work);
 195 extern void destroy_delayed_work_on_stack(struct delayed_work *work);
 196 static inline unsigned int work_static(struct work_struct *work)
 197 {
 198         return *work_data_bits(work) & WORK_STRUCT_STATIC;
 199 }
 200 #else
 201 static inline void __init_work(struct work_struct *work, int onstack) { }
 202 static inline void destroy_work_on_stack(struct work_struct *work) { }
 203 static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
 204 static 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  */
 289 enum {
 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  */
 366 extern struct workqueue_struct *system_wq;
 367 extern struct workqueue_struct *system_highpri_wq;
 368 extern struct workqueue_struct *system_long_wq;
 369 extern struct workqueue_struct *system_unbound_wq;
 370 extern struct workqueue_struct *system_freezable_wq;
 371 extern struct workqueue_struct *system_power_efficient_wq;
 372 extern struct workqueue_struct *system_freezable_power_efficient_wq;
 373
 374 extern 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
 437 extern void destroy_workqueue(struct workqueue_struct *wq);
 438
 439 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask);
 440 void free_workqueue_attrs(struct workqueue_attrs *attrs);
 441 int apply_workqueue_attrs(struct workqueue_struct *wq,
 442                           const struct workqueue_attrs *attrs);
 443 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
 444
 445 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
 446                         struct work_struct *work);
 447 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 448                         struct delayed_work *work, unsigned long delay);
 449 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
 450                         struct delayed_work *dwork, unsigned long delay);
 451
 452 extern void flush_workqueue(struct workqueue_struct *wq);
 453 extern void drain_workqueue(struct workqueue_struct *wq);
 454
 455 extern int schedule_on_each_cpu(work_func_t func);
 456
 457 int execute_in_process_context(work_func_t fn, struct execute_work *);
 458
 459 extern bool flush_work(struct work_struct *work);
 460 extern bool cancel_work(struct work_struct *work);
 461 extern bool cancel_work_sync(struct work_struct *work);
 462
 463 extern bool flush_delayed_work(struct delayed_work *dwork);
 464 extern bool cancel_delayed_work(struct delayed_work *dwork);
 465 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 466
 467 extern void workqueue_set_max_active(struct workqueue_struct *wq,
 468                                      int max_active);
 469 extern bool current_is_workqueue_rescuer(void);
 470 extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
 471 extern unsigned int work_busy(struct work_struct *work);
 472 extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
 473 extern void print_worker_info(const char *log_lvl, struct task_struct *task);
 474 extern 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  */
 486 static 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  */
 500 static 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  */
 515 static 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  */
 529 static 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  */
 545 static 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  */
 574 static 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  */
 588 static 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  */
 602 static 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
 609 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 610 {
 611         return fn(arg);
 612 }
 613 static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
 614 {
 615         return fn(arg);
 616 }
 617 #else
 618 long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
 619 long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
 620 #endif /* CONFIG_SMP */
 621
 622 #ifdef CONFIG_FREEZER
 623 extern void freeze_workqueues_begin(void);
 624 extern bool freeze_workqueues_busy(void);
 625 extern void thaw_workqueues(void);
 626 #endif /* CONFIG_FREEZER */
 627
 628 #ifdef CONFIG_SYSFS
 629 int workqueue_sysfs_register(struct workqueue_struct *wq);
 630 #else   /* CONFIG_SYSFS */
 631 static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
 632 { return 0; }
 633 #endif  /* CONFIG_SYSFS */
 634
 635 #ifdef CONFIG_WQ_WATCHDOG
 636 void wq_watchdog_touch(int cpu);
 637 #else   /* CONFIG_WQ_WATCHDOG */
 638 static inline void wq_watchdog_touch(int cpu) { }
 639 #endif  /* CONFIG_WQ_WATCHDOG */
 640
 641 #ifdef CONFIG_SMP
 642 int workqueue_prepare_cpu(unsigned int cpu);
 643 int workqueue_online_cpu(unsigned int cpu);
 644 int workqueue_offline_cpu(unsigned int cpu);
 645 #endif
 646
 647 int __init workqueue_init_early(void);
 648 int __init workqueue_init(void);
 649
 650 #endif