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 <asm/atomic.h>
  14
  15 struct workqueue_struct;
  16
  17 struct work_struct;
  18 typedef void (*work_func_t)(struct work_struct *work);
  19
  20 /*
  21  * The first word is the work queue pointer and the flags rolled into
  22  * one
  23  */
  24 #define work_data_bits(work) ((unsigned long *)(&(work)->data))
  25
  26 enum {
  27         WORK_STRUCT_PENDING_BIT = 0,    /* work item is pending execution */
  28         WORK_STRUCT_DELAYED_BIT = 1,    /* work item is delayed */
  29         WORK_STRUCT_CWQ_BIT     = 2,    /* data points to cwq */
  30         WORK_STRUCT_LINKED_BIT  = 3,    /* next work is linked to this one */
  31 #ifdef CONFIG_DEBUG_OBJECTS_WORK
  32         WORK_STRUCT_STATIC_BIT  = 4,    /* static initializer (debugobjects) */
  33         WORK_STRUCT_COLOR_SHIFT = 5,    /* color for workqueue flushing */
  34 #else
  35         WORK_STRUCT_COLOR_SHIFT = 4,    /* color for workqueue flushing */
  36 #endif
  37
  38         WORK_STRUCT_COLOR_BITS  = 4,
  39
  40         WORK_STRUCT_PENDING     = 1 << WORK_STRUCT_PENDING_BIT,
  41         WORK_STRUCT_DELAYED     = 1 << WORK_STRUCT_DELAYED_BIT,
  42         WORK_STRUCT_CWQ         = 1 << WORK_STRUCT_CWQ_BIT,
  43         WORK_STRUCT_LINKED      = 1 << WORK_STRUCT_LINKED_BIT,
  44 #ifdef CONFIG_DEBUG_OBJECTS_WORK
  45         WORK_STRUCT_STATIC      = 1 << WORK_STRUCT_STATIC_BIT,
  46 #else
  47         WORK_STRUCT_STATIC      = 0,
  48 #endif
  49
  50         /*
  51          * The last color is no color used for works which don't
  52          * participate in workqueue flushing.
  53          */
  54         WORK_NR_COLORS          = (1 << WORK_STRUCT_COLOR_BITS) - 1,
  55         WORK_NO_COLOR           = WORK_NR_COLORS,
  56
  57         /* special cpu IDs */
  58         WORK_CPU_UNBOUND        = NR_CPUS,
  59         WORK_CPU_NONE           = NR_CPUS + 1,
  60         WORK_CPU_LAST           = WORK_CPU_NONE,
  61
  62         /*
  63          * Reserve 7 bits off of cwq pointer w/ debugobjects turned
  64          * off.  This makes cwqs aligned to 256 bytes and allows 15
  65          * workqueue flush colors.
  66          */
  67         WORK_STRUCT_FLAG_BITS   = WORK_STRUCT_COLOR_SHIFT +
  68                                   WORK_STRUCT_COLOR_BITS,
  69
  70         WORK_STRUCT_FLAG_MASK   = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
  71         WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
  72         WORK_STRUCT_NO_CPU      = WORK_CPU_NONE << WORK_STRUCT_FLAG_BITS,
  73
  74         /* bit mask for work_busy() return values */
  75         WORK_BUSY_PENDING       = 1 << 0,
  76         WORK_BUSY_RUNNING       = 1 << 1,
  77 };
  78
  79 struct work_struct {
  80         atomic_long_t data;
  81         struct list_head entry;
  82         work_func_t func;
  83 #ifdef CONFIG_LOCKDEP
  84         struct lockdep_map lockdep_map;
  85 #endif
  86 };
  87
  88 #define WORK_DATA_INIT()        ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU)
  89 #define WORK_DATA_STATIC_INIT() \
  90         ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU | WORK_STRUCT_STATIC)
  91
  92 struct delayed_work {
  93         struct work_struct work;
  94         struct timer_list timer;
  95 };
  96
  97 static inline struct delayed_work *to_delayed_work(struct work_struct *work)
  98 {
  99         return container_of(work, struct delayed_work, work);
 100 }
 101
 102 struct execute_work {
 103         struct work_struct work;
 104 };
 105
 106 #ifdef CONFIG_LOCKDEP
 107 /*
 108  * NB: because we have to copy the lockdep_map, setting _key
 109  * here is required, otherwise it could get initialised to the
 110  * copy of the lockdep_map!
 111  */
 112 #define __WORK_INIT_LOCKDEP_MAP(n, k) \
 113         .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
 114 #else
 115 #define __WORK_INIT_LOCKDEP_MAP(n, k)
 116 #endif
 117
 118 #define __WORK_INITIALIZER(n, f) {                              \
 119         .data = WORK_DATA_STATIC_INIT(),                        \
 120         .entry  = { &(n).entry, &(n).entry },                   \
 121         .func = (f),                                            \
 122         __WORK_INIT_LOCKDEP_MAP(#n, &(n))                       \
 123         }
 124
 125 #define __DELAYED_WORK_INITIALIZER(n, f) {                      \
 126         .work = __WORK_INITIALIZER((n).work, (f)),              \
 127         .timer = TIMER_INITIALIZER(NULL, 0, 0),                 \
 128         }
 129
 130 #define __DEFERRED_WORK_INITIALIZER(n, f) {                     \
 131         .work = __WORK_INITIALIZER((n).work, (f)),              \
 132         .timer = TIMER_DEFERRED_INITIALIZER(NULL, 0, 0),        \
 133         }
 134
 135 #define DECLARE_WORK(n, f)                                      \
 136         struct work_struct n = __WORK_INITIALIZER(n, f)
 137
 138 #define DECLARE_DELAYED_WORK(n, f)                              \
 139         struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f)
 140
 141 #define DECLARE_DEFERRED_WORK(n, f)                             \
 142         struct delayed_work n = __DEFERRED_WORK_INITIALIZER(n, f)
 143
 144 /*
 145  * initialize a work item's function pointer
 146  */
 147 #define PREPARE_WORK(_work, _func)                              \
 148         do {                                                    \
 149                 (_work)->func = (_func);                        \
 150         } while (0)
 151
 152 #define PREPARE_DELAYED_WORK(_work, _func)                      \
 153         PREPARE_WORK(&(_work)->work, (_func))
 154
 155 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 156 extern void __init_work(struct work_struct *work, int onstack);
 157 extern void destroy_work_on_stack(struct work_struct *work);
 158 static inline unsigned int work_static(struct work_struct *work)
 159 {
 160         return *work_data_bits(work) & WORK_STRUCT_STATIC;
 161 }
 162 #else
 163 static inline void __init_work(struct work_struct *work, int onstack) { }
 164 static inline void destroy_work_on_stack(struct work_struct *work) { }
 165 static inline unsigned int work_static(struct work_struct *work) { return 0; }
 166 #endif
 167
 168 /*
 169  * initialize all of a work item in one go
 170  *
 171  * NOTE! No point in using "atomic_long_set()": using a direct
 172  * assignment of the work data initializer allows the compiler
 173  * to generate better code.
 174  */
 175 #ifdef CONFIG_LOCKDEP
 176 #define __INIT_WORK(_work, _func, _onstack)                             \
 177         do {                                                            \
 178                 static struct lock_class_key __key;                     \
 179                                                                         \
 180                 __init_work((_work), _onstack);                         \
 181                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 182                 lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0);\
 183                 INIT_LIST_HEAD(&(_work)->entry);                        \
 184                 PREPARE_WORK((_work), (_func));                         \
 185         } while (0)
 186 #else
 187 #define __INIT_WORK(_work, _func, _onstack)                             \
 188         do {                                                            \
 189                 __init_work((_work), _onstack);                         \
 190                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
 191                 INIT_LIST_HEAD(&(_work)->entry);                        \
 192                 PREPARE_WORK((_work), (_func));                         \
 193         } while (0)
 194 #endif
 195
 196 #define INIT_WORK(_work, _func)                                 \
 197         do {                                                    \
 198                 __INIT_WORK((_work), (_func), 0);               \
 199         } while (0)
 200
 201 #define INIT_WORK_ONSTACK(_work, _func)                         \
 202         do {                                                    \
 203                 __INIT_WORK((_work), (_func), 1);               \
 204         } while (0)
 205
 206 #define INIT_DELAYED_WORK(_work, _func)                         \
 207         do {                                                    \
 208                 INIT_WORK(&(_work)->work, (_func));             \
 209                 init_timer(&(_work)->timer);                    \
 210         } while (0)
 211
 212 #define INIT_DELAYED_WORK_ONSTACK(_work, _func)                 \
 213         do {                                                    \
 214                 INIT_WORK_ONSTACK(&(_work)->work, (_func));     \
 215                 init_timer_on_stack(&(_work)->timer);           \
 216         } while (0)
 217
 218 #define INIT_DELAYED_WORK_DEFERRABLE(_work, _func)              \
 219         do {                                                    \
 220                 INIT_WORK(&(_work)->work, (_func));             \
 221                 init_timer_deferrable(&(_work)->timer);         \
 222         } while (0)
 223
 224 /**
 225  * work_pending - Find out whether a work item is currently pending
 226  * @work: The work item in question
 227  */
 228 #define work_pending(work) \
 229         test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 230
 231 /**
 232  * delayed_work_pending - Find out whether a delayable work item is currently
 233  * pending
 234  * @work: The work item in question
 235  */
 236 #define delayed_work_pending(w) \
 237         work_pending(&(w)->work)
 238
 239 /**
 240  * work_clear_pending - for internal use only, mark a work item as not pending
 241  * @work: The work item in question
 242  */
 243 #define work_clear_pending(work) \
 244         clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
 245
 246 /*
 247  * Workqueue flags and constants.  For details, please refer to
 248  * Documentation/workqueue.txt.
 249  */
 250 enum {
 251         WQ_NON_REENTRANT        = 1 << 0, /* guarantee non-reentrance */
 252         WQ_UNBOUND              = 1 << 1, /* not bound to any cpu */
 253         WQ_FREEZABLE            = 1 << 2, /* freeze during suspend */
 254         WQ_MEM_RECLAIM          = 1 << 3, /* may be used for memory reclaim */
 255         WQ_HIGHPRI              = 1 << 4, /* high priority */
 256         WQ_CPU_INTENSIVE        = 1 << 5, /* cpu instensive workqueue */
 257
 258         WQ_DRAINING             = 1 << 6, /* internal: workqueue is draining */
 259         WQ_RESCUER              = 1 << 7, /* internal: workqueue has rescuer */
 260
 261         WQ_MAX_ACTIVE           = 512,    /* I like 512, better ideas? */
 262         WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
 263         WQ_DFL_ACTIVE           = WQ_MAX_ACTIVE / 2,
 264 };
 265
 266 /* unbound wq's aren't per-cpu, scale max_active according to #cpus */
 267 #define WQ_UNBOUND_MAX_ACTIVE   \
 268         max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)
 269
 270 /*
 271  * System-wide workqueues which are always present.
 272  *
 273  * system_wq is the one used by schedule[_delayed]_work[_on]().
 274  * Multi-CPU multi-threaded.  There are users which expect relatively
 275  * short queue flush time.  Don't queue works which can run for too
 276  * long.
 277  *
 278  * system_long_wq is similar to system_wq but may host long running
 279  * works.  Queue flushing might take relatively long.
 280  *
 281  * system_nrt_wq is non-reentrant and guarantees that any given work
 282  * item is never executed in parallel by multiple CPUs.  Queue
 283  * flushing might take relatively long.
 284  *
 285  * system_unbound_wq is unbound workqueue.  Workers are not bound to
 286  * any specific CPU, not concurrency managed, and all queued works are
 287  * executed immediately as long as max_active limit is not reached and
 288  * resources are available.
 289  *
 290  * system_freezable_wq is equivalent to system_wq except that it's
 291  * freezable.
 292  */
 293 extern struct workqueue_struct *system_wq;
 294 extern struct workqueue_struct *system_long_wq;
 295 extern struct workqueue_struct *system_nrt_wq;
 296 extern struct workqueue_struct *system_unbound_wq;
 297 extern struct workqueue_struct *system_freezable_wq;
 298
 299 extern struct workqueue_struct *
 300 __alloc_workqueue_key(const char *name, unsigned int flags, int max_active,
 301                       struct lock_class_key *key, const char *lock_name);
 302
 303 #ifdef CONFIG_LOCKDEP
 304 #define alloc_workqueue(name, flags, max_active)                \
 305 ({                                                              \
 306         static struct lock_class_key __key;                     \
 307         const char *__lock_name;                                \
 308                                                                 \
 309         if (__builtin_constant_p(name))                         \
 310                 __lock_name = (name);                           \
 311         else                                                    \
 312                 __lock_name = #name;                            \
 313                                                                 \
 314         __alloc_workqueue_key((name), (flags), (max_active),    \
 315                               &__key, __lock_name);             \
 316 })
 317 #else
 318 #define alloc_workqueue(name, flags, max_active)                \
 319         __alloc_workqueue_key((name), (flags), (max_active), NULL, NULL)
 320 #endif
 321
 322 /**
 323  * alloc_ordered_workqueue - allocate an ordered workqueue
 324  * @name: name of the workqueue
 325  * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
 326  *
 327  * Allocate an ordered workqueue.  An ordered workqueue executes at
 328  * most one work item at any given time in the queued order.  They are
 329  * implemented as unbound workqueues with @max_active of one.
 330  *
 331  * RETURNS:
 332  * Pointer to the allocated workqueue on success, %NULL on failure.
 333  */
 334 static inline struct workqueue_struct *
 335 alloc_ordered_workqueue(const char *name, unsigned int flags)
 336 {
 337         return alloc_workqueue(name, WQ_UNBOUND | flags, 1);
 338 }
 339
 340 #define create_workqueue(name)                                  \
 341         alloc_workqueue((name), WQ_MEM_RECLAIM, 1)
 342 #define create_freezable_workqueue(name)                        \
 343         alloc_workqueue((name), WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 344 #define create_singlethread_workqueue(name)                     \
 345         alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 346
 347 extern void destroy_workqueue(struct workqueue_struct *wq);
 348
 349 extern int queue_work(struct workqueue_struct *wq, struct work_struct *work);
 350 extern int queue_work_on(int cpu, struct workqueue_struct *wq,
 351                         struct work_struct *work);
 352 extern int queue_delayed_work(struct workqueue_struct *wq,
 353                         struct delayed_work *work, unsigned long delay);
 354 extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 355                         struct delayed_work *work, unsigned long delay);
 356
 357 extern void flush_workqueue(struct workqueue_struct *wq);
 358 extern void drain_workqueue(struct workqueue_struct *wq);
 359 extern void flush_scheduled_work(void);
 360
 361 extern int schedule_work(struct work_struct *work);
 362 extern int schedule_work_on(int cpu, struct work_struct *work);
 363 extern int schedule_delayed_work(struct delayed_work *work, unsigned long delay);
 364 extern int schedule_delayed_work_on(int cpu, struct delayed_work *work,
 365                                         unsigned long delay);
 366 extern int schedule_on_each_cpu(work_func_t func);
 367 extern int keventd_up(void);
 368
 369 int execute_in_process_context(work_func_t fn, struct execute_work *);
 370
 371 extern bool flush_work(struct work_struct *work);
 372 extern bool flush_work_sync(struct work_struct *work);
 373 extern bool cancel_work_sync(struct work_struct *work);
 374
 375 extern bool flush_delayed_work(struct delayed_work *dwork);
 376 extern bool flush_delayed_work_sync(struct delayed_work *work);
 377 extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 378
 379 extern void workqueue_set_max_active(struct workqueue_struct *wq,
 380                                      int max_active);
 381 extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
 382 extern unsigned int work_cpu(struct work_struct *work);
 383 extern unsigned int work_busy(struct work_struct *work);
 384
 385 /*
 386  * Kill off a pending schedule_delayed_work().  Note that the work callback
 387  * function may still be running on return from cancel_delayed_work(), unless
 388  * it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
 389  * cancel_work_sync() to wait on it.
 390  */
 391 static inline bool cancel_delayed_work(struct delayed_work *work)
 392 {
 393         bool ret;
 394
 395         ret = del_timer_sync(&work->timer);
 396         if (ret)
 397                 work_clear_pending(&work->work);
 398         return ret;
 399 }
 400
 401 /*
 402  * Like above, but uses del_timer() instead of del_timer_sync(). This means,
 403  * if it returns 0 the timer function may be running and the queueing is in
 404  * progress.
 405  */
 406 static inline bool __cancel_delayed_work(struct delayed_work *work)
 407 {
 408         bool ret;
 409
 410         ret = del_timer(&work->timer);
 411         if (ret)
 412                 work_clear_pending(&work->work);
 413         return ret;
 414 }
 415
 416 #ifndef CONFIG_SMP
 417 static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 418 {
 419         return fn(arg);
 420 }
 421 #else
 422 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
 423 #endif /* CONFIG_SMP */
 424
 425 #ifdef CONFIG_FREEZER
 426 extern void freeze_workqueues_begin(void);
 427 extern bool freeze_workqueues_busy(void);
 428 extern void thaw_workqueues(void);
 429 #endif /* CONFIG_FREEZER */
 430
 431 #endif