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/locking/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 	raw_spinlock_t		lock;
18 	unsigned int		count;
19 	struct list_head	wait_list;
20 };
21 
22 #define __SEMAPHORE_INITIALIZER(name, n)				\
23 {									\
24 	.lock		= __RAW_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 
sema_init(struct semaphore * sem,int val)32 static 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 extern void down(struct semaphore *sem);
40 extern int __must_check down_interruptible(struct semaphore *sem);
41 extern int __must_check down_killable(struct semaphore *sem);
42 extern int __must_check down_trylock(struct semaphore *sem);
43 extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
44 extern void up(struct semaphore *sem);
45 
46 #endif /* __LINUX_SEMAPHORE_H */
47