LXR linux/include/linux/semaphore.h

   1/*
   2 * Copyright (c) 2008 Intel Corporation
   3 * Author: Matthew Wilcox <willy@linux.intel.com>
   4 *
   5 * Distributed under the terms of the GNU GPL, version 2
   6 *
   7 * Please see kernel/semaphore.c for documentation of these functions
   8 */
   9#ifndef __LINUX_SEMAPHORE_H
  10#define __LINUX_SEMAPHORE_H
  11
  12#include <linux/list.h>
  13#include <linux/spinlock.h>
  14
  15/* Please don't access any members of this structure directly */
  16struct semaphore {
  17        spinlock_t              lock;
  18        unsigned int            count;
  19        struct list_head        wait_list;
  20};
  21
  22#define __SEMAPHORE_INITIALIZER(name, n)                                \
  23{                                                                       \
  24        .lock           = __SPIN_LOCK_UNLOCKED((name).lock),            \
  25        .count          = n,                                            \
  26        .wait_list      = LIST_HEAD_INIT((name).wait_list),             \
  27}
  28
  29#define DECLARE_MUTEX(name)     \
  30        struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
  31
  32static inline void sema_init(struct semaphore *sem, int val)
  33{
  34        static struct lock_class_key __key;
  35        *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
  36        lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0);
  37}
  38
  39#define init_MUTEX(sem)         sema_init(sem, 1)
  40#define init_MUTEX_LOCKED(sem)  sema_init(sem, 0)
  41
  42extern void down(struct semaphore *sem);
  43extern int __must_check down_interruptible(struct semaphore *sem);
  44extern int __must_check down_killable(struct semaphore *sem);
  45extern int __must_check down_trylock(struct semaphore *sem);
  46extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
  47extern void up(struct semaphore *sem);
  48
  49#endif /* __LINUX_SEMAPHORE_H */
  50