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 */
  16 struct 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 DEFINE_SEMAPHORE(name)  \
  30         struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
  31
  32 #define DECLARE_MUTEX(name)     \
  33         struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
  34
  35 static inline void sema_init(struct semaphore *sem, int val)
  36 {
  37         static struct lock_class_key __key;
  38         *sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
  39         lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0);
  40 }
  41
  42 #define init_MUTEX(sem)         sema_init(sem, 1)
  43 #define init_MUTEX_LOCKED(sem)  sema_init(sem, 0)
  44
  45 extern void down(struct semaphore *sem);
  46 extern int __must_check down_interruptible(struct semaphore *sem);
  47 extern int __must_check down_killable(struct semaphore *sem);
  48 extern int __must_check down_trylock(struct semaphore *sem);
  49 extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
  50 extern void up(struct semaphore *sem);
  51
  52 #endif /* __LINUX_SEMAPHORE_H */