linux/include/linux/workqueue.h
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   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
  15struct workqueue_struct;
  16
  17struct work_struct;
  18typedef 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
  26enum {
  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
  79struct 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
  92struct delayed_work {
  93        struct work_struct work;
  94        struct timer_list timer;
  95};
  96
  97static inline struct delayed_work *to_delayed_work(struct work_struct *work)
  98{
  99        return container_of(work, struct delayed_work, work);
 100}
 101
 102struct 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
 156extern void __init_work(struct work_struct *work, int onstack);
 157extern void destroy_work_on_stack(struct work_struct *work);
 158static inline unsigned int work_static(struct work_struct *work)
 159{
 160        return *work_data_bits(work) & WORK_STRUCT_STATIC;
 161}
 162#else
 163static inline void __init_work(struct work_struct *work, int onstack) { }
 164static inline void destroy_work_on_stack(struct work_struct *work) { }
 165static 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 */
 250enum {
 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 * system_nrt_freezable_wq is equivalent to system_nrt_wq except that
 294 * it's freezable.
 295 */
 296extern struct workqueue_struct *system_wq;
 297extern struct workqueue_struct *system_long_wq;
 298extern struct workqueue_struct *system_nrt_wq;
 299extern struct workqueue_struct *system_unbound_wq;
 300extern struct workqueue_struct *system_freezable_wq;
 301extern struct workqueue_struct *system_nrt_freezable_wq;
 302
 303extern struct workqueue_struct *
 304__alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
 305        struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);
 306
 307/**
 308 * alloc_workqueue - allocate a workqueue
 309 * @fmt: printf format for the name of the workqueue
 310 * @flags: WQ_* flags
 311 * @max_active: max in-flight work items, 0 for default
 312 * @args: args for @fmt
 313 *
 314 * Allocate a workqueue with the specified parameters.  For detailed
 315 * information on WQ_* flags, please refer to Documentation/workqueue.txt.
 316 *
 317 * The __lock_name macro dance is to guarantee that single lock_class_key
 318 * doesn't end up with different namesm, which isn't allowed by lockdep.
 319 *
 320 * RETURNS:
 321 * Pointer to the allocated workqueue on success, %NULL on failure.
 322 */
 323#ifdef CONFIG_LOCKDEP
 324#define alloc_workqueue(fmt, flags, max_active, args...)        \
 325({                                                              \
 326        static struct lock_class_key __key;                     \
 327        const char *__lock_name;                                \
 328                                                                \
 329        if (__builtin_constant_p(fmt))                          \
 330                __lock_name = (fmt);                            \
 331        else                                                    \
 332                __lock_name = #fmt;                             \
 333                                                                \
 334        __alloc_workqueue_key((fmt), (flags), (max_active),     \
 335                              &__key, __lock_name, ##args);     \
 336})
 337#else
 338#define alloc_workqueue(fmt, flags, max_active, args...)        \
 339        __alloc_workqueue_key((fmt), (flags), (max_active),     \
 340                              NULL, NULL, ##args)
 341#endif
 342
 343/**
 344 * alloc_ordered_workqueue - allocate an ordered workqueue
 345 * @fmt: printf format for the name of the workqueue
 346 * @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
 347 * @args: args for @fmt
 348 *
 349 * Allocate an ordered workqueue.  An ordered workqueue executes at
 350 * most one work item at any given time in the queued order.  They are
 351 * implemented as unbound workqueues with @max_active of one.
 352 *
 353 * RETURNS:
 354 * Pointer to the allocated workqueue on success, %NULL on failure.
 355 */
 356#define alloc_ordered_workqueue(fmt, flags, args...)            \
 357        alloc_workqueue(fmt, WQ_UNBOUND | (flags), 1, ##args)
 358
 359#define create_workqueue(name)                                  \
 360        alloc_workqueue((name), WQ_MEM_RECLAIM, 1)
 361#define create_freezable_workqueue(name)                        \
 362        alloc_workqueue((name), WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 363#define create_singlethread_workqueue(name)                     \
 364        alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
 365
 366extern void destroy_workqueue(struct workqueue_struct *wq);
 367
 368extern int queue_work(struct workqueue_struct *wq, struct work_struct *work);
 369extern int queue_work_on(int cpu, struct workqueue_struct *wq,
 370                        struct work_struct *work);
 371extern int queue_delayed_work(struct workqueue_struct *wq,
 372                        struct delayed_work *work, unsigned long delay);
 373extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 374                        struct delayed_work *work, unsigned long delay);
 375
 376extern void flush_workqueue(struct workqueue_struct *wq);
 377extern void drain_workqueue(struct workqueue_struct *wq);
 378extern void flush_scheduled_work(void);
 379
 380extern int schedule_work(struct work_struct *work);
 381extern int schedule_work_on(int cpu, struct work_struct *work);
 382extern int schedule_delayed_work(struct delayed_work *work, unsigned long delay);
 383extern int schedule_delayed_work_on(int cpu, struct delayed_work *work,
 384                                        unsigned long delay);
 385extern int schedule_on_each_cpu(work_func_t func);
 386extern int keventd_up(void);
 387
 388int execute_in_process_context(work_func_t fn, struct execute_work *);
 389
 390extern bool flush_work(struct work_struct *work);
 391extern bool flush_work_sync(struct work_struct *work);
 392extern bool cancel_work_sync(struct work_struct *work);
 393
 394extern bool flush_delayed_work(struct delayed_work *dwork);
 395extern bool flush_delayed_work_sync(struct delayed_work *work);
 396extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 397
 398extern void workqueue_set_max_active(struct workqueue_struct *wq,
 399                                     int max_active);
 400extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
 401extern unsigned int work_cpu(struct work_struct *work);
 402extern unsigned int work_busy(struct work_struct *work);
 403
 404/*
 405 * Kill off a pending schedule_delayed_work().  Note that the work callback
 406 * function may still be running on return from cancel_delayed_work(), unless
 407 * it returns 1 and the work doesn't re-arm itself. Run flush_workqueue() or
 408 * cancel_work_sync() to wait on it.
 409 */
 410static inline bool cancel_delayed_work(struct delayed_work *work)
 411{
 412        bool ret;
 413
 414        ret = del_timer_sync(&work->timer);
 415        if (ret)
 416                work_clear_pending(&work->work);
 417        return ret;
 418}
 419
 420/*
 421 * Like above, but uses del_timer() instead of del_timer_sync(). This means,
 422 * if it returns 0 the timer function may be running and the queueing is in
 423 * progress.
 424 */
 425static inline bool __cancel_delayed_work(struct delayed_work *work)
 426{
 427        bool ret;
 428
 429        ret = del_timer(&work->timer);
 430        if (ret)
 431                work_clear_pending(&work->work);
 432        return ret;
 433}
 434
 435#ifndef CONFIG_SMP
 436static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
 437{
 438        return fn(arg);
 439}
 440#else
 441long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
 442#endif /* CONFIG_SMP */
 443
 444#ifdef CONFIG_FREEZER
 445extern void freeze_workqueues_begin(void);
 446extern bool freeze_workqueues_busy(void);
 447extern void thaw_workqueues(void);
 448#endif /* CONFIG_FREEZER */
 449
 450#endif
 451
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