workqueue.h

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/*
 * workqueue.h --- work queue handling for Linux.
 */

#ifndef _LINUX_WORKQUEUE_H
#define _LINUX_WORKQUEUE_H

#include <linux/timer.h>
#include <linux/linkage.h>
#include <linux/bitops.h>
#include <linux/lockdep.h>
#include <linux/threads.h>
#include <linux/atomic.h>

struct workqueue_struct;

struct work_struct;
typedef void (*work_func_t)(struct work_struct *work);
void delayed_work_timer_fn(unsigned long __data);

/*
 * The first word is the work queue pointer and the flags rolled into
 * one
 */
#define work_data_bits(work) ((unsigned long *)(&(work)->data))

enum {
    WORK_STRUCT_PENDING_BIT = 0,    /* work item is pending execution */
    WORK_STRUCT_DELAYED_BIT = 1,    /* work item is delayed */
    WORK_STRUCT_CWQ_BIT = 2,    /* data points to cwq */
    WORK_STRUCT_LINKED_BIT  = 3,    /* next work is linked to this one */
#ifdef CONFIG_DEBUG_OBJECTS_WORK
    WORK_STRUCT_STATIC_BIT  = 4,    /* static initializer (debugobjects) */
    WORK_STRUCT_COLOR_SHIFT = 5,    /* color for workqueue flushing */
#else
    WORK_STRUCT_COLOR_SHIFT = 4,    /* color for workqueue flushing */
#endif

    WORK_STRUCT_COLOR_BITS  = 4,

    WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT,
    WORK_STRUCT_DELAYED = 1 << WORK_STRUCT_DELAYED_BIT,
    WORK_STRUCT_CWQ     = 1 << WORK_STRUCT_CWQ_BIT,
    WORK_STRUCT_LINKED  = 1 << WORK_STRUCT_LINKED_BIT,
#ifdef CONFIG_DEBUG_OBJECTS_WORK
    WORK_STRUCT_STATIC  = 1 << WORK_STRUCT_STATIC_BIT,
#else
    WORK_STRUCT_STATIC  = 0,
#endif

    /*
     * The last color is no color used for works which don't
     * participate in workqueue flushing.
     */
    WORK_NR_COLORS      = (1 << WORK_STRUCT_COLOR_BITS) - 1,
    WORK_NO_COLOR       = WORK_NR_COLORS,

    /* special cpu IDs */
    WORK_CPU_UNBOUND    = NR_CPUS,
    WORK_CPU_NONE       = NR_CPUS + 1,
    WORK_CPU_LAST       = WORK_CPU_NONE,

    /*
     * Reserve 7 bits off of cwq pointer w/ debugobjects turned
     * off.  This makes cwqs aligned to 256 bytes and allows 15
     * workqueue flush colors.
     */
    WORK_STRUCT_FLAG_BITS   = WORK_STRUCT_COLOR_SHIFT +
                  WORK_STRUCT_COLOR_BITS,

    /* data contains off-queue information when !WORK_STRUCT_CWQ */
    WORK_OFFQ_FLAG_BASE = WORK_STRUCT_FLAG_BITS,

    WORK_OFFQ_CANCELING = (1 << WORK_OFFQ_FLAG_BASE),

    WORK_OFFQ_FLAG_BITS = 1,
    WORK_OFFQ_CPU_SHIFT = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,

    /* convenience constants */
    WORK_STRUCT_FLAG_MASK   = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
    WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
    WORK_STRUCT_NO_CPU  = (unsigned long)WORK_CPU_NONE << WORK_OFFQ_CPU_SHIFT,

    /* bit mask for work_busy() return values */
    WORK_BUSY_PENDING   = 1 << 0,
    WORK_BUSY_RUNNING   = 1 << 1,
};

struct work_struct {
    atomic_long_t data;
    struct list_head entry;
    work_func_t func;
#ifdef CONFIG_LOCKDEP
    struct lockdep_map lockdep_map;
#endif
};

#define WORK_DATA_INIT()    ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU)
#define WORK_DATA_STATIC_INIT() \
    ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU | WORK_STRUCT_STATIC)

struct delayed_work {
    struct work_struct work;
    struct timer_list timer;
    int cpu;
};

static inline struct delayed_work *to_delayed_work(struct work_struct *work)
{
    return container_of(work, struct delayed_work, work);
}

struct execute_work {
    struct work_struct work;
};

#ifdef CONFIG_LOCKDEP
/*
 * NB: because we have to copy the lockdep_map, setting _key
 * here is required, otherwise it could get initialised to the
 * copy of the lockdep_map!
 */
#define __WORK_INIT_LOCKDEP_MAP(n, k) \
    .lockdep_map = STATIC_LOCKDEP_MAP_INIT(n, k),
#else
#define __WORK_INIT_LOCKDEP_MAP(n, k)
#endif

#define __WORK_INITIALIZER(n, f) {                  \
    .data = WORK_DATA_STATIC_INIT(),                \
    .entry  = { &(n).entry, &(n).entry },               \
    .func = (f),                            \
    __WORK_INIT_LOCKDEP_MAP(#n, &(n))               \
    }

#define __DELAYED_WORK_INITIALIZER(n, f, tflags) {          \
    .work = __WORK_INITIALIZER((n).work, (f)),          \
    .timer = __TIMER_INITIALIZER(delayed_work_timer_fn,     \
                     0, (unsigned long)&(n),        \
                     (tflags) | TIMER_IRQSAFE),     \
    }

#define DECLARE_WORK(n, f)                      \
    struct work_struct n = __WORK_INITIALIZER(n, f)

#define DECLARE_DELAYED_WORK(n, f)                  \
    struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, 0)

#define DECLARE_DEFERRABLE_WORK(n, f)                   \
    struct delayed_work n = __DELAYED_WORK_INITIALIZER(n, f, TIMER_DEFERRABLE)

/*
 * initialize a work item's function pointer
 */
#define PREPARE_WORK(_work, _func)                  \
    do {                                \
        (_work)->func = (_func);                \
    } while (0)

#define PREPARE_DELAYED_WORK(_work, _func)              \
    PREPARE_WORK(&(_work)->work, (_func))

#ifdef CONFIG_DEBUG_OBJECTS_WORK
extern void __init_work(struct work_struct *work, int onstack);
extern void destroy_work_on_stack(struct work_struct *work);
static inline unsigned int work_static(struct work_struct *work)
{
    return *work_data_bits(work) & WORK_STRUCT_STATIC;
}
#else
static inline void __init_work(struct work_struct *work, int onstack) { }
static inline void destroy_work_on_stack(struct work_struct *work) { }
static inline unsigned int work_static(struct work_struct *work) { return 0; }
#endif

/*
 * initialize all of a work item in one go
 *
 * NOTE! No point in using "atomic_long_set()": using a direct
 * assignment of the work data initializer allows the compiler
 * to generate better code.
 */
#ifdef CONFIG_LOCKDEP
#define __INIT_WORK(_work, _func, _onstack)             \
    do {                                \
        static struct lock_class_key __key;         \
                                    \
        __init_work((_work), _onstack);             \
        (_work)->data = (atomic_long_t) WORK_DATA_INIT();   \
        lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0); \
        INIT_LIST_HEAD(&(_work)->entry);            \
        PREPARE_WORK((_work), (_func));             \
    } while (0)
#else
#define __INIT_WORK(_work, _func, _onstack)             \
    do {                                \
        __init_work((_work), _onstack);             \
        (_work)->data = (atomic_long_t) WORK_DATA_INIT();   \
        INIT_LIST_HEAD(&(_work)->entry);            \
        PREPARE_WORK((_work), (_func));             \
    } while (0)
#endif

#define INIT_WORK(_work, _func)                     \
    do {                                \
        __INIT_WORK((_work), (_func), 0);           \
    } while (0)

#define INIT_WORK_ONSTACK(_work, _func)                 \
    do {                                \
        __INIT_WORK((_work), (_func), 1);           \
    } while (0)

#define __INIT_DELAYED_WORK(_work, _func, _tflags)          \
    do {                                \
        INIT_WORK(&(_work)->work, (_func));         \
        __setup_timer(&(_work)->timer, delayed_work_timer_fn,   \
                  (unsigned long)(_work),           \
                  (_tflags) | TIMER_IRQSAFE);       \
    } while (0)

#define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)      \
    do {                                \
        INIT_WORK_ONSTACK(&(_work)->work, (_func));     \
        __setup_timer_on_stack(&(_work)->timer,         \
                       delayed_work_timer_fn,       \
                       (unsigned long)(_work),      \
                       (_tflags) | TIMER_IRQSAFE);  \
    } while (0)

#define INIT_DELAYED_WORK(_work, _func)                 \
    __INIT_DELAYED_WORK(_work, _func, 0)

#define INIT_DELAYED_WORK_ONSTACK(_work, _func)             \
    __INIT_DELAYED_WORK_ONSTACK(_work, _func, 0)

#define INIT_DEFERRABLE_WORK(_work, _func)              \
    __INIT_DELAYED_WORK(_work, _func, TIMER_DEFERRABLE)

#define INIT_DEFERRABLE_WORK_ONSTACK(_work, _func)          \
    __INIT_DELAYED_WORK_ONSTACK(_work, _func, TIMER_DEFERRABLE)

#define work_pending(work) \
    test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))

#define delayed_work_pending(w) \
    work_pending(&(w)->work)

#define work_clear_pending(work) \
    clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))

/*
 * Workqueue flags and constants.  For details, please refer to
 * Documentation/workqueue.txt.
 */
enum {
    WQ_NON_REENTRANT    = 1 << 0, /* guarantee non-reentrance */
    WQ_UNBOUND      = 1 << 1, /* not bound to any cpu */
    WQ_FREEZABLE        = 1 << 2, /* freeze during suspend */
    WQ_MEM_RECLAIM      = 1 << 3, /* may be used for memory reclaim */
    WQ_HIGHPRI      = 1 << 4, /* high priority */
    WQ_CPU_INTENSIVE    = 1 << 5, /* cpu instensive workqueue */

    WQ_DRAINING     = 1 << 6, /* internal: workqueue is draining */
    WQ_RESCUER      = 1 << 7, /* internal: workqueue has rescuer */

    WQ_MAX_ACTIVE       = 512,    /* I like 512, better ideas? */
    WQ_MAX_UNBOUND_PER_CPU  = 4,      /* 4 * #cpus for unbound wq */
    WQ_DFL_ACTIVE       = WQ_MAX_ACTIVE / 2,
};

/* unbound wq's aren't per-cpu, scale max_active according to #cpus */
#define WQ_UNBOUND_MAX_ACTIVE   \
    max_t(int, WQ_MAX_ACTIVE, num_possible_cpus() * WQ_MAX_UNBOUND_PER_CPU)

/*
 * System-wide workqueues which are always present.
 *
 * system_wq is the one used by schedule[_delayed]_work[_on]().
 * Multi-CPU multi-threaded.  There are users which expect relatively
 * short queue flush time.  Don't queue works which can run for too
 * long.
 *
 * system_long_wq is similar to system_wq but may host long running
 * works.  Queue flushing might take relatively long.
 *
 * system_unbound_wq is unbound workqueue.  Workers are not bound to
 * any specific CPU, not concurrency managed, and all queued works are
 * executed immediately as long as max_active limit is not reached and
 * resources are available.
 *
 * system_freezable_wq is equivalent to system_wq except that it's
 * freezable.
 */
extern struct workqueue_struct *system_wq;
extern struct workqueue_struct *system_long_wq;
extern struct workqueue_struct *system_unbound_wq;
extern struct workqueue_struct *system_freezable_wq;

static inline struct workqueue_struct * __deprecated __system_nrt_wq(void)
{
    return system_wq;
}

static inline struct workqueue_struct * __deprecated __system_nrt_freezable_wq(void)
{
    return system_freezable_wq;
}

/* equivlalent to system_wq and system_freezable_wq, deprecated */
#define system_nrt_wq           __system_nrt_wq()
#define system_nrt_freezable_wq     __system_nrt_freezable_wq()

extern struct workqueue_struct *
__alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active,
    struct lock_class_key *key, const char *lock_name, ...) __printf(1, 6);

#ifdef CONFIG_LOCKDEP
#define alloc_workqueue(fmt, flags, max_active, args...)        \
({                                  \
    static struct lock_class_key __key;             \
    const char *__lock_name;                    \
                                    \
    if (__builtin_constant_p(fmt))                  \
        __lock_name = (fmt);                    \
    else                                \
        __lock_name = #fmt;                 \
                                    \
    __alloc_workqueue_key((fmt), (flags), (max_active),     \
                  &__key, __lock_name, ##args);     \
})
#else
#define alloc_workqueue(fmt, flags, max_active, args...)        \
    __alloc_workqueue_key((fmt), (flags), (max_active),     \
                  NULL, NULL, ##args)
#endif

#define alloc_ordered_workqueue(fmt, flags, args...)            \
    alloc_workqueue(fmt, WQ_UNBOUND | (flags), 1, ##args)

#define create_workqueue(name)                      \
    alloc_workqueue((name), WQ_MEM_RECLAIM, 1)
#define create_freezable_workqueue(name)                \
    alloc_workqueue((name), WQ_FREEZABLE | WQ_UNBOUND | WQ_MEM_RECLAIM, 1)
#define create_singlethread_workqueue(name)             \
    alloc_workqueue((name), WQ_UNBOUND | WQ_MEM_RECLAIM, 1)

extern void destroy_workqueue(struct workqueue_struct *wq);

extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
            struct work_struct *work);
extern bool queue_work(struct workqueue_struct *wq, struct work_struct *work);
extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
            struct delayed_work *work, unsigned long delay);
extern bool queue_delayed_work(struct workqueue_struct *wq,
            struct delayed_work *work, unsigned long delay);
extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
            struct delayed_work *dwork, unsigned long delay);
extern bool mod_delayed_work(struct workqueue_struct *wq,
            struct delayed_work *dwork, unsigned long delay);

extern void flush_workqueue(struct workqueue_struct *wq);
extern void drain_workqueue(struct workqueue_struct *wq);
extern void flush_scheduled_work(void);

extern bool schedule_work_on(int cpu, struct work_struct *work);
extern bool schedule_work(struct work_struct *work);
extern bool schedule_delayed_work_on(int cpu, struct delayed_work *work,
                     unsigned long delay);
extern bool schedule_delayed_work(struct delayed_work *work,
                  unsigned long delay);
extern int schedule_on_each_cpu(work_func_t func);
extern int keventd_up(void);

int execute_in_process_context(work_func_t fn, struct execute_work *);

extern bool flush_work(struct work_struct *work);
extern bool cancel_work_sync(struct work_struct *work);

extern bool flush_delayed_work(struct delayed_work *dwork);
extern bool cancel_delayed_work(struct delayed_work *dwork);
extern bool cancel_delayed_work_sync(struct delayed_work *dwork);

extern void workqueue_set_max_active(struct workqueue_struct *wq,
                     int max_active);
extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
extern unsigned int work_cpu(struct work_struct *work);
extern unsigned int work_busy(struct work_struct *work);

/*
 * Like above, but uses del_timer() instead of del_timer_sync(). This means,
 * if it returns 0 the timer function may be running and the queueing is in
 * progress.
 */
static inline bool __deprecated __cancel_delayed_work(struct delayed_work *work)
{
    bool ret;

    ret = del_timer(&work->timer);
    if (ret)
        work_clear_pending(&work->work);
    return ret;
}

/* used to be different but now identical to flush_work(), deprecated */
static inline bool __deprecated flush_work_sync(struct work_struct *work)
{
    return flush_work(work);
}

/* used to be different but now identical to flush_delayed_work(), deprecated */
static inline bool __deprecated flush_delayed_work_sync(struct delayed_work *dwork)
{
    return flush_delayed_work(dwork);
}

#ifndef CONFIG_SMP
static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
{
    return fn(arg);
}
#else
long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
#endif /* CONFIG_SMP */

#ifdef CONFIG_FREEZER
extern void freeze_workqueues_begin(void);
extern bool freeze_workqueues_busy(void);
extern void thaw_workqueues(void);
#endif /* CONFIG_FREEZER */

#endif