1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  * Copyright (c) 2008 Intel Corporation
4  * Author: Matthew Wilcox <willy@linux.intel.com>
5  *
6  * Please see kernel/locking/semaphore.c for documentation of these functions
7  */
8 #ifndef __LINUX_SEMAPHORE_H
9 #define __LINUX_SEMAPHORE_H
10 
11 #include <linux/list.h>
12 #include <linux/spinlock.h>
13 
14 /* Please don't access any members of this structure directly */
15 struct semaphore {
16 	raw_spinlock_t		lock;
17 	unsigned int		count;
18 	struct list_head	wait_list;
19 };
20 
21 #define __SEMAPHORE_INITIALIZER(name, n)				\
22 {									\
23 	.lock		= __RAW_SPIN_LOCK_UNLOCKED((name).lock),	\
24 	.count		= n,						\
25 	.wait_list	= LIST_HEAD_INIT((name).wait_list),		\
26 }
27 
28 #define DEFINE_SEMAPHORE(name)	\
29 	struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
30 
sema_init(struct semaphore * sem,int val)31 static inline void sema_init(struct semaphore *sem, int val)
32 {
33 	static struct lock_class_key __key;
34 	*sem = (struct semaphore) __SEMAPHORE_INITIALIZER(*sem, val);
35 	lockdep_init_map(&sem->lock.dep_map, "semaphore->lock", &__key, 0);
36 }
37 
38 extern void down(struct semaphore *sem);
39 extern int __must_check down_interruptible(struct semaphore *sem);
40 extern int __must_check down_killable(struct semaphore *sem);
41 extern int __must_check down_trylock(struct semaphore *sem);
42 extern int __must_check down_timeout(struct semaphore *sem, long jiffies);
43 extern void up(struct semaphore *sem);
44 
45 #endif /* __LINUX_SEMAPHORE_H */
46