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