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
  15 struct workqueue_struct;
  16
  17 struct work_struct;
  18 typedef void (*work_func_t)(struct work_struct *work);
  19 void delayed_work_timer_fn(unsigned long __data);
  20
  21 /*
  22  * The first word is the work queue pointer and the flags rolled into
  23  * one
  24  */
  25 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
  26
  27 enum {
  28         WORK_STRUCT_PENDING_BIT = 0,    /* work item is pending execution */
  29         WORK_STRUCT_DELAYED_BIT = 1,    /* work item is delayed */
  30         WORK_STRUCT_CWQ_BIT     = 2,    /* data points to cwq */
  31         WORK_STRUCT_LINKED_BIT  = 3,    /* next work is linked to this one */
  32 #ifdef CONFIG_DEBUG_OBJECTS_WORK
  33         WORK_STRUCT_STATIC_BIT  = 4,    /* static initializer (debugobjects) */
  34         WORK_STRUCT_COLOR_SHIFT = 5,    /* color for workqueue flushing */
  35 #else
  36         WORK_STRUCT_COLOR_SHIFT = 4,    /* color for workqueue flushing */
  37 #endif
  38
  39         WORK_STRUCT_COLOR_BITS  = 4,
  40
  41         WORK_STRUCT_PENDING     = 1 << WORK_STRUCT_PENDING_BIT,
  42         WORK_STRUCT_DELAYED     = 1 << WORK_STRUCT_DELAYED_BIT,
  43         WORK_STRUCT_CWQ         = 1 << WORK_STRUCT_CWQ_BIT,
  44         WORK_STRUCT_LINKED      = 1 << WORK_STRUCT_LINKED_BIT,
  45 #ifdef CONFIG_DEBUG_OBJECTS_WORK
  46         WORK_STRUCT_STATIC      = 1 << WORK_STRUCT_STATIC_BIT,
  47 #else
  48         WORK_STRUCT_STATIC      = 0,
  49 #endif
  50
  51         /*
  52          * The last color is no color used for works which don't
  53          * participate in workqueue flushing.
  54          */
  55         WORK_NR_COLORS          = (1 << WORK_STRUCT_COLOR_BITS) - 1,
  56         WORK_NO_COLOR           = WORK_NR_COLORS,
  57
  58         /* special cpu IDs */
  59         WORK_CPU_UNBOUND        = NR_CPUS,
  60         WORK_CPU_NONE           = NR_CPUS + 1,
  61         WORK_CPU_LAST           = WORK_CPU_NONE,
  62
  63         /*
  64          * Reserve 7 bits off of cwq pointer w/ debugobjects turned
  65          * off.  This makes cwqs aligned to 256 bytes and allows 15
  66          * workqueue 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_CWQ */
  72         WORK_OFFQ_FLAG_BASE     = WORK_STRUCT_FLAG_BITS,
  73
  74         WORK_OFFQ_CANCELING     = (1 << WORK_OFFQ_FLAG_BASE),
  75
  76         WORK_OFFQ_FLAG_BITS     = 1,
  77         WORK_OFFQ_CPU_SHIFT     = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
  78
  79         /* convenience constants */
  80         WORK_STRUCT_FLAG_MASK   = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
  81         WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
  82         WORK_STRUCT_NO_CPU      = (unsigned long)WORK_CPU_NONE << WORK_OFFQ_CPU_SHIFT,
  83
  84         /* bit mask for work_busy() return values */
  85         WORK_BUSY_PENDING       = 1 << 0,
  86         WORK_BUSY_RUNNING       = 1 << 1,
  87 };
  88
  89 struct work_struct {
  90         atomic_long_t data;
  91         struct list_head entry;
  92         work_func_t func;
  93 #ifdef CONFIG_LOCKDEP
  94         struct lockdep_map lockdep_map;
  95 #endif
  96 };
  97
  98 #define WORK_DATA_INIT()        ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU)
  99 #define WORK_DATA_STATIC_INIT() \
 100         ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU | WORK_STRUCT_STATIC)
 101
 102 struct delayed_work {
 103         struct work_struct work;
 104         struct timer_list timer;
 105         int cpu;
 106 };
 107
 108 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
 109 {
 110         return container_of(work, struct delayed_work, work);
 111 }
 112
 113 struct execute_work {
 114         struct work_struct work;
 115 };
 116
 117 #ifdef CONFIG_LOCKDEP
 118 /*
 119  * NB: because we have to copy the lockdep_map, setting _key
 120  * here is required, otherwise it could get initialised to the
 121  * copy of the lockdep_map!
 122  */
 123 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
 124         .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
 125 #else
 126 #define __WORK_INIT_LOCKDEP_MAP(n, k)
 127 #endif
 128
 129 #define __WORK_INITIALIZER(n, f) {                                      \
 130         .data = WORK_DATA_STATIC_INIT(),                                \
 131         .entry  = { &(n).entry, &(n).entry },                           \
 132         .func = (f),                                                    \
 133         __WORK_INIT_LOCKDEP_MAP(#n, &(n))                               \
 134         }
 135
 136 #define __DELAYED_WORK_INITIALIZER(n, f) {                              \
 137         .work = __WORK_INITIALIZER((n).work, (f)),                      \
 138         .timer = TIMER_INITIALIZER(delayed_work_timer_fn,               \
 139                                 0, (unsigned long)&(n)),                \
 140         }
 141
 142 #define __DEFERRED_WORK_INITIALIZER(n, f) {                             \
 143         .work = __WORK_INITIALIZER((n).work, (f)),                      \
 144         .timer = TIMER_DEFERRED_INITIALIZER(delayed_work_timer_fn,      \
 145                                 0, (unsigned long)&(n)),                \
 146         }
 147
 148 #define DECLARE_WORK(n, f)                                              \
 149         struct work_struct n = __WORK_INITIALIZER(n, f)
 150
 151 #define DECLARE_DELAYED_WORK(n, f)                                      \
 152         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
 153
 154 #define DECLARE_DEFERRED_WORK(n, f)                                     \
 155         struct delayed_work n = __DEFERRED_WORK_INITIALIZER(n, f)
 156
 157 /*
 158  * initialize a work item's function pointer
 159  */
 160 #define PREPARE_WORK(_work, _func)                                      \
 161         do {                                                            \
 162                 (_work)->func = (_func);                                \
 163         } while (0)
 164
 165 #define PREPARE_DELAYED_WORK(_work, _func)                              \
 166         PREPARE_WORK(&(_work)->work, (_func))
 167
 168 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 169 extern void __init_work(struct work_struct *work, int onstack);
 170 extern void destroy_work_on_stack(struct work_struct *work);
 171 static inline unsigned int work_static(struct work_struct *work)
 172 {
 173         return *work_data_bits(work) & WORK_STRUCT_STATIC;
 174 }
 175 #else
 176 static inline void __init_work(struct work_struct *work, int onstack) { }
 177 static inline void destroy_work_on_stack(struct work_struct *work) { }
 178 static inline unsigned int work_static(struct work_struct *work) { return 0; }
 179 #endif
 180
 181 /*
 182  * initialize all of a work item in one go
 183  *
 184  * NOTE! No point in using "atomic_long_set()": using a direct
 185  * assignment of the work data initializer allows the compiler
 186  * to generate better code.
 187  */
 188 #ifdef CONFIG_LOCKDEP
 189 #define __INIT_WORK(_work, _func, _onstack)                             \
 190         do {                                                            \
 191                 static struct lock_class_key __key;                     \
 192                                                                         \
 193                 __init_work((_work), _onstack);                         \
 194                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 195                 lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
 196                 INIT_LIST_HEAD(&(_work)->entry);                        \
 197                 PREPARE_WORK((_work), (_func));                         \
 198         } while (0)
 199 #else
 200 #define __INIT_WORK(_work, _func, _onstack)                             \
 201         do {                                                            \
 202                 __init_work((_work), _onstack);                         \
 203                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 204                 INIT_LIST_HEAD(&(_work)->entry);                        \
 205                 PREPARE_WORK((_work), (_func));                         \
 206         } while (0)
 207 #endif
 208
 209 #define INIT_WORK(_work, _func)                                         \
 210         do {                                                            \
 211                 __INIT_WORK((_work), (_func), 0);                       \
 212         } while (0)
 213
 214 #define INIT_WORK_ONSTACK(_work, _func)                                 \
 215         do {                                                            \
 216                 __INIT_WORK((_work), (_func), 1);                       \
 217         } while (0)
 218
 219 #define INIT_DELAYED_WORK(_work, _func)                                 \
 220         do {                                                            \
 221                 INIT_WORK(&(_work)->work, (_func));                     \
 222                 init_timer(&(_work)->timer);                            \
 223                 (_work)->timer.function = delayed_work_timer_fn;        \
 224                 (_work)->timer.data = (unsigned long)(_work);           \
 225         } while (0)
 226
 227 #define INIT_DELAYED_WORK_ONSTACK(_work, _func)                         \
 228         do {                                                            \
 229                 INIT_WORK_ONSTACK(&(_work)->work, (_func));             \
 230                 init_timer_on_stack(&(_work)->timer);                   \
 231                 (_work)->timer.function = delayed_work_timer_fn;        \
 232                 (_work)->timer.data = (unsigned long)(_work);           \
 233         } while (0)
 234
 235 #define INIT_DELAYED_WORK_DEFERRABLE(_work, _func)                      \
 236         do {                                                            \
 237                 INIT_WORK(&(_work)->work, (_func));                     \
 238                 init_timer_deferrable(&(_work)->timer);                 \
 239                 (_work)->timer.function = delayed_work_timer_fn;        \
 240                 (_work)->timer.data = (unsigned long)(_work);           \
 241         } while (0)
 242
 243 /**
 244  * work_pending - Find out whether a work item is currently pending
 245  * @work: The work item in question
 246  */
 247 #define work_pending(work) \
 248         test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 249
 250 /**
 251  * delayed_work_pending - Find out whether a delayable work item is currently
 252  * pending
 253  * @work: The work item in question
 254  */
 255 #define delayed_work_pending(w) \
 256         work_pending(&(w)->work)
 257
 258 /**
 259  * work_clear_pending - for internal use only, mark a work item as not pending
 260  * @work: The work item in question
 261  */
 262 #define work_clear_pending(work) \
 263         clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 264
 265 /*
 266  * Workqueue flags and constants.  For details, please refer to
 267  * Documentation/workqueue.txt.
 268  */
 269 enum {
 270         WQ_NON_REENTRANT        = 1 << 0, /* guarantee non-reentrance */
 271         WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
 272         WQ_FREEZABLE            = 1 << 2, /* freeze during suspend */
 273         WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
 274         WQ_HIGHPRI              = 1 << 4, /* high priority */
 275         WQ_CPU_INTENSIVE        = 1 << 5, /* cpu instensive workqueue */
 276
 277         WQ_DRAINING             = 1 << 6, /* internal: workqueue is draining */
 278         WQ_RESCUER              = 1 << 7, /* internal: workqueue has rescuer */
 279
 280         WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
 281         WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
 282         WQ_DFL_ACTIVE           = WQ_MAX_ACTIVE / 2,
 283 };
 284
 285 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
 286 #define WQ_UNBOUND_MAX_ACTIVE   \
 287         max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
 288
 289 /*
 290  * System-wide workqueues which are always present.
 291  *
 292  * system_wq is the one used by schedule[_delayed]_work[_on]().
 293  * Multi-CPU multi-threaded.  There are users which expect relatively
 294  * short queue flush time.  Don't queue works which can run for too
 295  * long.
 296  *
 297  * system_long_wq is similar to system_wq but may host long running
 298  * works.  Queue flushing might take relatively long.
 299  *
 300  * system_unbound_wq is unbound workqueue.  Workers are not bound to
 301  * any specific CPU, not concurrency managed, and all queued works are
 302  * executed immediately as long as max_active limit is not reached and
 303  * resources are available.
 304  *
 305  * system_freezable_wq is equivalent to system_wq except that it's
 306  * freezable.
 307  */
 308 extern struct workqueue_struct *system_wq;
 309 extern struct workqueue_struct *system_long_wq;
 310 extern struct workqueue_struct *system_unbound_wq;
 311 extern struct workqueue_struct *system_freezable_wq;
 312
 313 static inline struct workqueue_struct * __deprecated __system_nrt_wq(void)
 314 {
 315         return system_wq;
 316 }
 317
 318 static inline struct workqueue_struct * __deprecated __system_nrt_freezable_wq(void)
 319 {
 320         return system_freezable_wq;
 321 }
 322
 323 /* equivlalent to system_wq and system_freezable_wq, deprecated */
 324 #define system_nrt_wq                   __system_nrt_wq()
 325 #define system_nrt_freezable_wq         __system_nrt_freezable_wq()
 326
 327 extern struct workqueue_struct *
 328 __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
 329         struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
 330
 331 /**
 332  * alloc_workqueue - allocate a workqueue
 333  * @fmt: printf format for the name of the workqueue
 334  * @flags: WQ_* flags
 335  * @max_active: max in-flight work items, 0 for default
 336  * @args: args for @fmt
 337  *
 338  * Allocate a workqueue with the specified parameters.  For detailed
 339  * information on WQ_* flags, please refer to Documentation/workqueue.txt.
 340  *
 341  * The __lock_name macro dance is to guarantee that single lock_class_key
 342  * doesn't end up with different namesm, which isn't allowed by lockdep.
 343  *
 344  * RETURNS:
 345  * Pointer to the allocated workqueue on success, %NULL on failure.
 346  */
 347 #ifdef CONFIG_LOCKDEP
 348 #define alloc_workqueue(fmt, flags, max_active, args...)                \
 349 ({                                                                      \
 350         static struct lock_class_key __key;                             \
 351         const char *__lock_name;                                        \
 352                                                                         \
 353         if (__builtin_constant_p(fmt))                                  \
 354                 __lock_name = (fmt);                                    \
 355         else                                                            \
 356                 __lock_name = #fmt;                                     \
 357                                                                         \
 358         __alloc_workqueue_key((fmt), (flags), (max_active),             \
 359                               &__key, __lock_name, ##args);             \
 360 })
 361 #else
 362 #define alloc_workqueue(fmt, flags, max_active, args...)                \
 363         __alloc_workqueue_key((fmt), (flags), (max_active),             \
 364                               NULL, NULL, ##args)
 365 #endif
 366
 367 /**
 368  * alloc_ordered_workqueue - allocate an ordered workqueue
 369  * @fmt: printf format for the name of the workqueue
 370  * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
 371  * @args: args for @fmt
 372  *
 373  * Allocate an ordered workqueue.  An ordered workqueue executes at
 374  * most one work item at any given time in the queued order.  They are
 375  * implemented as unbound workqueues with @max_active of one.
 376  *
 377  * RETURNS:
 378  * Pointer to the allocated workqueue on success, %NULL on failure.
 379  */
 380 #define alloc_ordered_workqueue(fmt, flags, args...)                    \
 381         alloc_workqueue(fmt, WQ_UNBOUND | (flags), 1, ##args)
 382
 383 #define create_workqueue(name)                                          \
 384         alloc_workqueue((name), WQ_MEM_RECLAIM, 1)
 385 #define create_freezable_workqueue(name)                                \
 386         alloc_workqueue((name), WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 387 #define create_singlethread_workqueue(name)                             \
 388         alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 389
 390 extern void destroy_workqueue(struct workqueue_struct *wq);
 391
 392 extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
 393                         struct work_struct *work);
 394 extern bool queue_work(struct workqueue_struct *wq, struct work_struct *work);
 395 extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 396                         struct delayed_work *work, unsigned long delay);
 397 extern bool queue_delayed_work(struct workqueue_struct *wq,
 398                         struct delayed_work *work, unsigned long delay);
 399 extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
 400                         struct delayed_work *dwork, unsigned long delay);
 401 extern bool mod_delayed_work(struct workqueue_struct *wq,
 402                         struct delayed_work *dwork, unsigned long delay);
 403
 404 extern void flush_workqueue(struct workqueue_struct *wq);
 405 extern void drain_workqueue(struct workqueue_struct *wq);
 406 extern void flush_scheduled_work(void);
 407
 408 extern bool schedule_work_on(int cpu, struct work_struct *work);
 409 extern bool schedule_work(struct work_struct *work);
 410 extern bool schedule_delayed_work_on(int cpu, struct delayed_work *work,
 411                                      unsigned long delay);
 412 extern bool schedule_delayed_work(struct delayed_work *work,
 413                                   unsigned long delay);
 414 extern int schedule_on_each_cpu(work_func_t func);
 415 extern int keventd_up(void);
 416
 417 int execute_in_process_context(work_func_t fn, struct execute_work *);
 418
 419 extern bool flush_work(struct work_struct *work);
 420 extern bool cancel_work_sync(struct work_struct *work);
 421
 422 extern bool flush_delayed_work(struct delayed_work *dwork);
 423 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 424
 425 extern void workqueue_set_max_active(struct workqueue_struct *wq,
 426                                      int max_active);
 427 extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
 428 extern unsigned int work_cpu(struct work_struct *work);
 429 extern unsigned int work_busy(struct work_struct *work);
 430
 431 /*
 432  * Kill off a pending schedule_delayed_work().  Note that the work callback
 433  * function may still be running on return from cancel_delayed_work(), unless
 434  * it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
 435  * cancel_work_sync() to wait on it.
 436  */
 437 static inline bool cancel_delayed_work(struct delayed_work *work)
 438 {
 439         bool ret;
 440
 441         ret = del_timer_sync(&work->timer);
 442         if (ret)
 443                 work_clear_pending(&work->work);
 444         return ret;
 445 }
 446
 447 /*
 448  * Like above, but uses del_timer() instead of del_timer_sync(). This means,
 449  * if it returns 0 the timer function may be running and the queueing is in
 450  * progress.
 451  */
 452 static inline bool __cancel_delayed_work(struct delayed_work *work)
 453 {
 454         bool ret;
 455
 456         ret = del_timer(&work->timer);
 457         if (ret)
 458                 work_clear_pending(&work->work);
 459         return ret;
 460 }
 461
 462 /* used to be different but now identical to flush_work(), deprecated */
 463 static inline bool __deprecated flush_work_sync(struct work_struct *work)
 464 {
 465         return flush_work(work);
 466 }
 467
 468 /* used to be different but now identical to flush_delayed_work(), deprecated */
 469 static inline bool __deprecated flush_delayed_work_sync(struct delayed_work *dwork)
 470 {
 471         return flush_delayed_work(dwork);
 472 }
 473
 474 #ifndef CONFIG_SMP
 475 static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 476 {
 477         return fn(arg);
 478 }
 479 #else
 480 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
 481 #endif /* CONFIG_SMP */
 482
 483 #ifdef CONFIG_FREEZER
 484 extern void freeze_workqueues_begin(void);
 485 extern bool freeze_workqueues_busy(void);
 486 extern void thaw_workqueues(void);
 487 #endif /* CONFIG_FREEZER */
 488
 489 #endif