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