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 #include <linux/rcupdate.h>
  17
  18 struct workqueue_struct;
  19
  20 struct work_struct;
  21 typedef void (*work_func_t)(struct work_struct *work);
  22 void delayed_work_timer_fn(struct timer_list *t);
  23
  24 /*
  25  * The first word is the work queue pointer and the flags rolled into
  26  * one
  27  */
  28 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
  29
  30 enum {
  31         WORK_STRUCT_PENDING_BIT = 0,    /* work item is pending execution */
  32         WORK_STRUCT_INACTIVE_BIT= 1,    /* work item is inactive */
  33         WORK_STRUCT_PWQ_BIT     = 2,    /* data points to pwq */
  34         WORK_STRUCT_LINKED_BIT  = 3,    /* next work is linked to this one */
  35 #ifdef CONFIG_DEBUG_OBJECTS_WORK
  36         WORK_STRUCT_STATIC_BIT  = 4,    /* static initializer (debugobjects) */
  37         WORK_STRUCT_COLOR_SHIFT = 5,    /* color for workqueue flushing */
  38 #else
  39         WORK_STRUCT_COLOR_SHIFT = 4,    /* color for workqueue flushing */
  40 #endif
  41
  42         WORK_STRUCT_COLOR_BITS  = 4,
  43
  44         WORK_STRUCT_PENDING     = 1 << WORK_STRUCT_PENDING_BIT,
  45         WORK_STRUCT_INACTIVE    = 1 << WORK_STRUCT_INACTIVE_BIT,
  46         WORK_STRUCT_PWQ         = 1 << WORK_STRUCT_PWQ_BIT,
  47         WORK_STRUCT_LINKED      = 1 << WORK_STRUCT_LINKED_BIT,
  48 #ifdef CONFIG_DEBUG_OBJECTS_WORK
  49         WORK_STRUCT_STATIC      = 1 << WORK_STRUCT_STATIC_BIT,
  50 #else
  51         WORK_STRUCT_STATIC      = 0,
  52 #endif
  53
  54         WORK_NR_COLORS          = (1 << WORK_STRUCT_COLOR_BITS),
  55
  56         /* not bound to any CPU, prefer the local CPU */
  57         WORK_CPU_UNBOUND        = NR_CPUS,
  58
  59         /*
  60          * Reserve 8 bits off of pwq pointer w/ debugobjects turned off.
  61          * This makes pwqs aligned to 256 bytes and allows 16 workqueue
  62          * flush colors.
  63          */
  64         WORK_STRUCT_FLAG_BITS   = WORK_STRUCT_COLOR_SHIFT +
  65                                   WORK_STRUCT_COLOR_BITS,
  66
  67         /* data contains off-queue information when !WORK_STRUCT_PWQ */
  68         WORK_OFFQ_FLAG_BASE     = WORK_STRUCT_COLOR_SHIFT,
  69
  70         __WORK_OFFQ_CANCELING   = WORK_OFFQ_FLAG_BASE,
  71         WORK_OFFQ_CANCELING     = (1 << __WORK_OFFQ_CANCELING),
  72
  73         /*
  74          * When a work item is off queue, its high bits point to the last
  75          * pool it was on.  Cap at 31 bits and use the highest number to
  76          * indicate that no pool is associated.
  77          */
  78         WORK_OFFQ_FLAG_BITS     = 1,
  79         WORK_OFFQ_POOL_SHIFT    = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
  80         WORK_OFFQ_LEFT          = BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
  81         WORK_OFFQ_POOL_BITS     = WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
  82         WORK_OFFQ_POOL_NONE     = (1LU << WORK_OFFQ_POOL_BITS) - 1,
  83
  84         /* convenience constants */
  85         WORK_STRUCT_FLAG_MASK   = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
  86         WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
  87         WORK_STRUCT_NO_POOL     = (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
  88
  89         /* bit mask for work_busy() return values */
  90         WORK_BUSY_PENDING       = 1 << 0,
  91         WORK_BUSY_RUNNING       = 1 << 1,
  92
  93         /* maximum string length for set_worker_desc() */
  94         WORKER_DESC_LEN         = 24,
  95 };
  96
  97 struct work_struct {
  98         atomic_long_t data;
  99         struct list_head entry;
 100         work_func_t func;
 101 #ifdef CONFIG_LOCKDEP
 102         struct lockdep_map lockdep_map;
 103 #endif
 104 };
 105
 106 #define WORK_DATA_INIT()        ATOMIC_LONG_INIT((unsigned long)WORK_STRUCT_NO_POOL)
 107 #define WORK_DATA_STATIC_INIT() \
 108         ATOMIC_LONG_INIT((unsigned long)(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC))
 109
 110 struct delayed_work {
 111         struct work_struct work;
 112         struct timer_list timer;
 113
 114         /* target workqueue and CPU ->timer uses to queue ->work */
 115         struct workqueue_struct *wq;
 116         int cpu;
 117 };
 118
 119 struct rcu_work {
 120         struct work_struct work;
 121         struct rcu_head rcu;
 122
 123         /* target workqueue ->rcu uses to queue ->work */
 124         struct workqueue_struct *wq;
 125 };
 126
 127 /**
 128  * struct workqueue_attrs - A struct for workqueue attributes.
 129  *
 130  * This can be used to change attributes of an unbound workqueue.
 131  */
 132 struct workqueue_attrs {
 133         /**
 134          * @nice: nice level
 135          */
 136         int nice;
 137
 138         /**
 139          * @cpumask: allowed CPUs
 140          */
 141         cpumask_var_t cpumask;
 142
 143         /**
 144          * @no_numa: disable NUMA affinity
 145          *
 146          * Unlike other fields, ``no_numa`` isn't a property of a worker_pool. It
 147          * only modifies how :c:func:`apply_workqueue_attrs` select pools and thus
 148          * doesn't participate in pool hash calculations or equality comparisons.
 149          */
 150         bool no_numa;
 151 };
 152
 153 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
 154 {
 155         return container_of(work, struct delayed_work, work);
 156 }
 157
 158 static inline struct rcu_work *to_rcu_work(struct work_struct *work)
 159 {
 160         return container_of(work, struct rcu_work, work);
 161 }
 162
 163 struct execute_work {
 164         struct work_struct work;
 165 };
 166
 167 #ifdef CONFIG_LOCKDEP
 168 /*
 169  * NB: because we have to copy the lockdep_map, setting _key
 170  * here is required, otherwise it could get initialised to the
 171  * copy of the lockdep_map!
 172  */
 173 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
 174         .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
 175 #else
 176 #define __WORK_INIT_LOCKDEP_MAP(n, k)
 177 #endif
 178
 179 #define __WORK_INITIALIZER(n, f) {                                      \
 180         .data = WORK_DATA_STATIC_INIT(),                                \
 181         .entry  = { &(n).entry, &(n).entry },                           \
 182         .func = (f),                                                    \
 183         __WORK_INIT_LOCKDEP_MAP(#n, &(n))                               \
 184         }
 185
 186 #define __DELAYED_WORK_INITIALIZER(n, f, tflags) {                      \
 187         .work = __WORK_INITIALIZER((n).work, (f)),                      \
 188         .timer = __TIMER_INITIALIZER(delayed_work_timer_fn,\
 189                                      (tflags) | TIMER_IRQSAFE),         \
 190         }
 191
 192 #define DECLARE_WORK(n, f)                                              \
 193         struct work_struct n = __WORK_INITIALIZER(n, f)
 194
 195 #define DECLARE_DELAYED_WORK(n, f)                                      \
 196         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)
 197
 198 #define DECLARE_DEFERRABLE_WORK(n, f)                                   \
 199         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)
 200
 201 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 202 extern void __init_work(struct work_struct *work, int onstack);
 203 extern void destroy_work_on_stack(struct work_struct *work);
 204 extern void destroy_delayed_work_on_stack(struct delayed_work *work);
 205 static inline unsigned int work_static(struct work_struct *work)
 206 {
 207         return *work_data_bits(work) & WORK_STRUCT_STATIC;
 208 }
 209 #else
 210 static inline void __init_work(struct work_struct *work, int onstack) { }
 211 static inline void destroy_work_on_stack(struct work_struct *work) { }
 212 static inline void destroy_delayed_work_on_stack(struct delayed_work *work) { }
 213 static inline unsigned int work_static(struct work_struct *work) { return 0; }
 214 #endif
 215
 216 /*
 217  * initialize all of a work item in one go
 218  *
 219  * NOTE! No point in using "atomic_long_set()": using a direct
 220  * assignment of the work data initializer allows the compiler
 221  * to generate better code.
 222  */
 223 #ifdef CONFIG_LOCKDEP
 224 #define __INIT_WORK(_work, _func, _onstack)                             \
 225         do {                                                            \
 226                 static struct lock_class_key __key;                     \
 227                                                                         \
 228                 __init_work((_work), _onstack);                         \
 229                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 230                 lockdep_init_map(&(_work)->lockdep_map, "(work_completion)"#_work, &__key, 0); \
 231                 INIT_LIST_HEAD(&(_work)->entry);                        \
 232                 (_work)->func = (_func);                                \
 233         } while (0)
 234 #else
 235 #define __INIT_WORK(_work, _func, _onstack)                             \
 236         do {                                                            \
 237                 __init_work((_work), _onstack);                         \
 238                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 239                 INIT_LIST_HEAD(&(_work)->entry);                        \
 240                 (_work)->func = (_func);                                \
 241         } while (0)
 242 #endif
 243
 244 #define INIT_WORK(_work, _func)                                         \
 245         __INIT_WORK((_work), (_func), 0)
 246
 247 #define INIT_WORK_ONSTACK(_work, _func)                                 \
 248         __INIT_WORK((_work), (_func), 1)
 249
 250 #define __INIT_DELAYED_WORK(_work, _func, _tflags)                      \
 251         do {                                                            \
 252                 INIT_WORK(&(_work)->work, (_func));                     \
 253                 __init_timer(&(_work)->timer,                           \
 254                              delayed_work_timer_fn,                     \
 255                              (_tflags) | TIMER_IRQSAFE);                \
 256         } while (0)
 257
 258 #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)              \
 259         do {                                                            \
 260                 INIT_WORK_ONSTACK(&(_work)->work, (_func));             \
 261                 __init_timer_on_stack(&(_work)->timer,                  \
 262                                       delayed_work_timer_fn,            \
 263                                       (_tflags) | TIMER_IRQSAFE);       \
 264         } while (0)
 265
 266 #define INIT_DELAYED_WORK(_work, _func)                                 \
 267         __INIT_DELAYED_WORK(_work, _func, 0)
 268
 269 #define INIT_DELAYED_WORK_ONSTACK(_work, _func)                         \
 270         __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)
 271
 272 #define INIT_DEFERRABLE_WORK(_work, _func)                              \
 273         __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)
 274
 275 #define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func)                      \
 276         __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)
 277
 278 #define INIT_RCU_WORK(_work, _func)                                     \
 279         INIT_WORK(&(_work)->work, (_func))
 280
 281 #define INIT_RCU_WORK_ONSTACK(_work, _func)                             \
 282         INIT_WORK_ONSTACK(&(_work)->work, (_func))
 283
 284 /**
 285  * work_pending - Find out whether a work item is currently pending
 286  * @work: The work item in question
 287  */
 288 #define work_pending(work) \
 289         test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 290
 291 /**
 292  * delayed_work_pending - Find out whether a delayable work item is currently
 293  * pending
 294  * @w: The work item in question
 295  */
 296 #define delayed_work_pending(w) \
 297         work_pending(&(w)->work)
 298
 299 /*
 300  * Workqueue flags and constants.  For details, please refer to
 301  * Documentation/core-api/workqueue.rst.
 302  */
 303 enum {
 304         WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
 305         WQ_FREEZABLE            = 1 << 2, /* freeze during suspend */
 306         WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
 307         WQ_HIGHPRI              = 1 << 4, /* high priority */
 308         WQ_CPU_INTENSIVE        = 1 << 5, /* cpu intensive workqueue */
 309         WQ_SYSFS                = 1 << 6, /* visible in sysfs, see workqueue_sysfs_register() */
 310
 311         /*
 312          * Per-cpu workqueues are generally preferred because they tend to
 313          * show better performance thanks to cache locality.  Per-cpu
 314          * workqueues exclude the scheduler from choosing the CPU to
 315          * execute the worker threads, which has an unfortunate side effect
 316          * of increasing power consumption.
 317          *
 318          * The scheduler considers a CPU idle if it doesn't have any task
 319          * to execute and tries to keep idle cores idle to conserve power;
 320          * however, for example, a per-cpu work item scheduled from an
 321          * interrupt handler on an idle CPU will force the scheduler to
 322          * execute the work item on that CPU breaking the idleness, which in
 323          * turn may lead to more scheduling choices which are sub-optimal
 324          * in terms of power consumption.
 325          *
 326          * Workqueues marked with WQ_POWER_EFFICIENT are per-cpu by default
 327          * but become unbound if workqueue.power_efficient kernel param is
 328          * specified.  Per-cpu workqueues which are identified to
 329          * contribute significantly to power-consumption are identified and
 330          * marked with this flag and enabling the power_efficient mode
 331          * leads to noticeable power saving at the cost of small
 332          * performance disadvantage.
 333          *
 334          * http://thread.gmane.org/gmane.linux.kernel/1480396
 335          */
 336         WQ_POWER_EFFICIENT      = 1 << 7,
 337
 338         __WQ_DRAINING           = 1 << 16, /* internal: workqueue is draining */
 339         __WQ_ORDERED            = 1 << 17, /* internal: workqueue is ordered */
 340         __WQ_LEGACY             = 1 << 18, /* internal: create*_workqueue() */
 341         __WQ_ORDERED_EXPLICIT   = 1 << 19, /* internal: alloc_ordered_workqueue() */
 342
 343         WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
 344         WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
 345         WQ_DFL_ACTIVE           = WQ_MAX_ACTIVE / 2,
 346 };
 347
 348 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
 349 #define WQ_UNBOUND_MAX_ACTIVE   \
 350         max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
 351
 352 /*
 353  * System-wide workqueues which are always present.
 354  *
 355  * system_wq is the one used by schedule[_delayed]_work[_on]().
 356  * Multi-CPU multi-threaded.  There are users which expect relatively
 357  * short queue flush time.  Don't queue works which can run for too
 358  * long.
 359  *
 360  * system_highpri_wq is similar to system_wq but for work items which
 361  * require WQ_HIGHPRI.
 362  *
 363  * system_long_wq is similar to system_wq but may host long running
 364  * works.  Queue flushing might take relatively long.
 365  *
 366  * system_unbound_wq is unbound workqueue.  Workers are not bound to
 367  * any specific CPU, not concurrency managed, and all queued works are
 368  * executed immediately as long as max_active limit is not reached and
 369  * resources are available.
 370  *
 371  * system_freezable_wq is equivalent to system_wq except that it's
 372  * freezable.
 373  *
 374  * *_power_efficient_wq are inclined towards saving power and converted
 375  * into WQ_UNBOUND variants if 'wq_power_efficient' is enabled; otherwise,
 376  * they are same as their non-power-efficient counterparts - e.g.
 377  * system_power_efficient_wq is identical to system_wq if
 378  * 'wq_power_efficient' is disabled.  See WQ_POWER_EFFICIENT for more info.
 379  */
 380 extern struct workqueue_struct *system_wq;
 381 extern struct workqueue_struct *system_highpri_wq;
 382 extern struct workqueue_struct *system_long_wq;
 383 extern struct workqueue_struct *system_unbound_wq;
 384 extern struct workqueue_struct *system_freezable_wq;
 385 extern struct workqueue_struct *system_power_efficient_wq;
 386 extern struct workqueue_struct *system_freezable_power_efficient_wq;
 387
 388 /**
 389  * alloc_workqueue - allocate a workqueue
 390  * @fmt: printf format for the name of the workqueue
 391  * @flags: WQ_* flags
 392  * @max_active: max in-flight work items, 0 for default
 393  * remaining args: args for @fmt
 394  *
 395  * Allocate a workqueue with the specified parameters.  For detailed
 396  * information on WQ_* flags, please refer to
 397  * Documentation/core-api/workqueue.rst.
 398  *
 399  * RETURNS:
 400  * Pointer to the allocated workqueue on success, %NULL on failure.
 401  */
 402 struct workqueue_struct *alloc_workqueue(const char *fmt,
 403                                          unsigned int flags,
 404                                          int max_active, ...);
 405
 406 /**
 407  * alloc_ordered_workqueue - allocate an ordered workqueue
 408  * @fmt: printf format for the name of the workqueue
 409  * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
 410  * @args...: args for @fmt
 411  *
 412  * Allocate an ordered workqueue.  An ordered workqueue executes at
 413  * most one work item at any given time in the queued order.  They are
 414  * implemented as unbound workqueues with @max_active of one.
 415  *
 416  * RETURNS:
 417  * Pointer to the allocated workqueue on success, %NULL on failure.
 418  */
 419 #define alloc_ordered_workqueue(fmt, flags, args...)                    \
 420         alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED |                \
 421                         __WQ_ORDERED_EXPLICIT | (flags), 1, ##args)
 422
 423 #define create_workqueue(name)                                          \
 424         alloc_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, 1, (name))
 425 #define create_freezable_workqueue(name)                                \
 426         alloc_workqueue("%s", __WQ_LEGACY | WQ_FREEZABLE | WQ_UNBOUND | \
 427                         WQ_MEM_RECLAIM, 1, (name))
 428 #define create_singlethread_workqueue(name)                             \
 429         alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
 430
 431 extern void destroy_workqueue(struct workqueue_struct *wq);
 432
 433 struct workqueue_attrs *alloc_workqueue_attrs(void);
 434 void free_workqueue_attrs(struct workqueue_attrs *attrs);
 435 int apply_workqueue_attrs(struct workqueue_struct *wq,
 436                           const struct workqueue_attrs *attrs);
 437 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask);
 438
 439 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
 440                         struct work_struct *work);
 441 extern bool queue_work_node(int node, struct workqueue_struct *wq,
 442                             struct work_struct *work);
 443 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 444                         struct delayed_work *work, unsigned long delay);
 445 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
 446                         struct delayed_work *dwork, unsigned long delay);
 447 extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork);
 448
 449 extern void flush_workqueue(struct workqueue_struct *wq);
 450 extern void drain_workqueue(struct workqueue_struct *wq);
 451
 452 extern int schedule_on_each_cpu(work_func_t func);
 453
 454 int execute_in_process_context(work_func_t fn, struct execute_work *);
 455
 456 extern bool flush_work(struct work_struct *work);
 457 extern bool cancel_work_sync(struct work_struct *work);
 458
 459 extern bool flush_delayed_work(struct delayed_work *dwork);
 460 extern bool cancel_delayed_work(struct delayed_work *dwork);
 461 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 462
 463 extern bool flush_rcu_work(struct rcu_work *rwork);
 464
 465 extern void workqueue_set_max_active(struct workqueue_struct *wq,
 466                                      int max_active);
 467 extern struct work_struct *current_work(void);
 468 extern bool current_is_workqueue_rescuer(void);
 469 extern bool workqueue_congested(int cpu, struct workqueue_struct *wq);
 470 extern unsigned int work_busy(struct work_struct *work);
 471 extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
 472 extern void print_worker_info(const char *log_lvl, struct task_struct *task);
 473 extern void show_workqueue_state(void);
 474 extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task);
 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  * Memory-ordering properties:  If it returns %true, guarantees that all stores
 487  * preceding the call to queue_work() in the program order will be visible from
 488  * the CPU which will execute @work by the time such work executes, e.g.,
 489  *
 490  * { x is initially 0 }
 491  *
 492  *   CPU0                               CPU1
 493  *
 494  *   WRITE_ONCE(x, 1);                  [ @work is being executed ]
 495  *   r0 = queue_work(wq, work);           r1 = READ_ONCE(x);
 496  *
 497  * Forbids: r0 == true && r1 == 0
 498  */
 499 static inline bool queue_work(struct workqueue_struct *wq,
 500                               struct work_struct *work)
 501 {
 502         return queue_work_on(WORK_CPU_UNBOUND, wq, work);
 503 }
 504
 505 /**
 506  * queue_delayed_work - queue work on a workqueue after delay
 507  * @wq: workqueue to use
 508  * @dwork: delayable work to queue
 509  * @delay: number of jiffies to wait before queueing
 510  *
 511  * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
 512  */
 513 static inline bool queue_delayed_work(struct workqueue_struct *wq,
 514                                       struct delayed_work *dwork,
 515                                       unsigned long delay)
 516 {
 517         return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 518 }
 519
 520 /**
 521  * mod_delayed_work - modify delay of or queue a delayed work
 522  * @wq: workqueue to use
 523  * @dwork: work to queue
 524  * @delay: number of jiffies to wait before queueing
 525  *
 526  * mod_delayed_work_on() on local CPU.
 527  */
 528 static inline bool mod_delayed_work(struct workqueue_struct *wq,
 529                                     struct delayed_work *dwork,
 530                                     unsigned long delay)
 531 {
 532         return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay);
 533 }
 534
 535 /**
 536  * schedule_work_on - put work task on a specific cpu
 537  * @cpu: cpu to put the work task on
 538  * @work: job to be done
 539  *
 540  * This puts a job on a specific cpu
 541  */
 542 static inline bool schedule_work_on(int cpu, struct work_struct *work)
 543 {
 544         return queue_work_on(cpu, system_wq, work);
 545 }
 546
 547 /**
 548  * schedule_work - put work task in global workqueue
 549  * @work: job to be done
 550  *
 551  * Returns %false if @work was already on the kernel-global workqueue and
 552  * %true otherwise.
 553  *
 554  * This puts a job in the kernel-global workqueue if it was not already
 555  * queued and leaves it in the same position on the kernel-global
 556  * workqueue otherwise.
 557  *
 558  * Shares the same memory-ordering properties of queue_work(), cf. the
 559  * DocBook header of queue_work().
 560  */
 561 static inline bool schedule_work(struct work_struct *work)
 562 {
 563         return queue_work(system_wq, work);
 564 }
 565
 566 /**
 567  * flush_scheduled_work - ensure that any scheduled work has run to completion.
 568  *
 569  * Forces execution of the kernel-global workqueue and blocks until its
 570  * completion.
 571  *
 572  * Think twice before calling this function!  It's very easy to get into
 573  * trouble if you don't take great care.  Either of the following situations
 574  * will lead to deadlock:
 575  *
 576  *      One of the work items currently on the workqueue needs to acquire
 577  *      a lock held by your code or its caller.
 578  *
 579  *      Your code is running in the context of a work routine.
 580  *
 581  * They will be detected by lockdep when they occur, but the first might not
 582  * occur very often.  It depends on what work items are on the workqueue and
 583  * what locks they need, which you have no control over.
 584  *
 585  * In most situations flushing the entire workqueue is overkill; you merely
 586  * need to know that a particular work item isn't queued and isn't running.
 587  * In such cases you should use cancel_delayed_work_sync() or
 588  * cancel_work_sync() instead.
 589  */
 590 static inline void flush_scheduled_work(void)
 591 {
 592         flush_workqueue(system_wq);
 593 }
 594
 595 /**
 596  * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
 597  * @cpu: cpu to use
 598  * @dwork: job to be done
 599  * @delay: number of jiffies to wait
 600  *
 601  * After waiting for a given time this puts a job in the kernel-global
 602  * workqueue on the specified CPU.
 603  */
 604 static inline bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
 605                                             unsigned long delay)
 606 {
 607         return queue_delayed_work_on(cpu, system_wq, dwork, delay);
 608 }
 609
 610 /**
 611  * schedule_delayed_work - put work task in global workqueue after delay
 612  * @dwork: job to be done
 613  * @delay: number of jiffies to wait or 0 for immediate execution
 614  *
 615  * After waiting for a given time this puts a job in the kernel-global
 616  * workqueue.
 617  */
 618 static inline bool schedule_delayed_work(struct delayed_work *dwork,
 619                                          unsigned long delay)
 620 {
 621         return queue_delayed_work(system_wq, dwork, delay);
 622 }
 623
 624 #ifndef CONFIG_SMP
 625 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 626 {
 627         return fn(arg);
 628 }
 629 static inline long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg)
 630 {
 631         return fn(arg);
 632 }
 633 #else
 634 long work_on_cpu(int cpu, long (*fn)(void *), void *arg);
 635 long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg);
 636 #endif /* CONFIG_SMP */
 637
 638 #ifdef CONFIG_FREEZER
 639 extern void freeze_workqueues_begin(void);
 640 extern bool freeze_workqueues_busy(void);
 641 extern void thaw_workqueues(void);
 642 #endif /* CONFIG_FREEZER */
 643
 644 #ifdef CONFIG_SYSFS
 645 int workqueue_sysfs_register(struct workqueue_struct *wq);
 646 #else   /* CONFIG_SYSFS */
 647 static inline int workqueue_sysfs_register(struct workqueue_struct *wq)
 648 { return 0; }
 649 #endif  /* CONFIG_SYSFS */
 650
 651 #ifdef CONFIG_WQ_WATCHDOG
 652 void wq_watchdog_touch(int cpu);
 653 #else   /* CONFIG_WQ_WATCHDOG */
 654 static inline void wq_watchdog_touch(int cpu) { }
 655 #endif  /* CONFIG_WQ_WATCHDOG */
 656
 657 #ifdef CONFIG_SMP
 658 int workqueue_prepare_cpu(unsigned int cpu);
 659 int workqueue_online_cpu(unsigned int cpu);
 660 int workqueue_offline_cpu(unsigned int cpu);
 661 #endif
 662
 663 void __init workqueue_init_early(void);
 664 void __init workqueue_init(void);
 665
 666 #endif