/*
   * Copyright (c) 2008 Intel Corporation
   * Author: Matthew Wilcox <willy@linux.intel.com>
   *
   * Distributed under the terms of the GNU GPL, version 2
   *

   * Please see kernel/semaphore.c for documentation of these functions

   */
  #ifndef __LINUX_SEMAPHORE_H
  #define __LINUX_SEMAPHORE_H
  
  #include <linux/list.h>
  #include <linux/spinlock.h>

  /* Please don't access any members of this structure directly */

  struct semaphore {

  	raw_spinlock_t		lock;

  	unsigned int		count;

  	struct list_head	wait_list;
  };
  
  #define __SEMAPHORE_INITIALIZER(name, n)				\
  {									\

  	.lock		= __RAW_SPIN_LOCK_UNLOCKED((name).lock),	\

  	.count		= n,						\
  	.wait_list	= LIST_HEAD_INIT((name).wait_list),		\
  }

  #define DEFINE_SEMAPHORE(name)	\
  	struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)

  static inline void sema_init(struct semaphore *sem, int val)
  {
  	static struct lock_class_key __key;
  	*sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
  	lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0);
  }

  extern void down(struct semaphore *sem);

  extern int __must_check down_interruptible(struct semaphore *sem);

  extern int __must_check down_killable(struct semaphore *sem);

  extern int __must_check down_trylock(struct semaphore *sem);

  extern int __must_check down_timeout(struct semaphore *sem, long jiffies);

  extern void up(struct semaphore *sem);
  
  #endif /* __LINUX_SEMAPHORE_H */