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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/*
2 * linux/include/asm-arm/semaphore.h
3 */
4#ifndef __ASM_ARM_SEMAPHORE_H
5#define __ASM_ARM_SEMAPHORE_H
6
7#include <linux/linkage.h>
8#include <linux/spinlock.h>
9#include <linux/wait.h>
10#include <linux/rwsem.h>
11
12#include <asm/atomic.h>
13#include <asm/locks.h>
14
15struct semaphore {
16 atomic_t count;
17 int sleepers;
18 wait_queue_head_t wait;
19};
20
21#define __SEMAPHORE_INIT(name, n) \
22{ \
23 .count = ATOMIC_INIT(n), \
24 .sleepers = 0, \
25 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \
26}
27
28#define __MUTEX_INITIALIZER(name) \
29 __SEMAPHORE_INIT(name,1)
30
31#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
32 struct semaphore name = __SEMAPHORE_INIT(name,count)
33
34#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
35#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
36
37static inline void sema_init(struct semaphore *sem, int val)
38{
39 atomic_set(&sem->count, val);
40 sem->sleepers = 0;
41 init_waitqueue_head(&sem->wait);
42}
43
44static inline void init_MUTEX(struct semaphore *sem)
45{
46 sema_init(sem, 1);
47}
48
49static inline void init_MUTEX_LOCKED(struct semaphore *sem)
50{
51 sema_init(sem, 0);
52}
53
54/*
55 * special register calling convention
56 */
57asmlinkage void __down_failed(void);
58asmlinkage int __down_interruptible_failed(void);
59asmlinkage int __down_trylock_failed(void);
60asmlinkage void __up_wakeup(void);
61
62extern void __down(struct semaphore * sem);
63extern int __down_interruptible(struct semaphore * sem);
64extern int __down_trylock(struct semaphore * sem);
65extern void __up(struct semaphore * sem);
66
67/*
68 * This is ugly, but we want the default case to fall through.
69 * "__down" is the actual routine that waits...
70 */
71static inline void down(struct semaphore * sem)
72{
73 might_sleep();
74 __down_op(sem, __down_failed);
75}
76
77/*
78 * This is ugly, but we want the default case to fall through.
79 * "__down_interruptible" is the actual routine that waits...
80 */
81static inline int down_interruptible (struct semaphore * sem)
82{
83 might_sleep();
84 return __down_op_ret(sem, __down_interruptible_failed);
85}
86
87static inline int down_trylock(struct semaphore *sem)
88{
89 return __down_op_ret(sem, __down_trylock_failed);
90}
91
92/*
93 * Note! This is subtle. We jump to wake people up only if
94 * the semaphore was negative (== somebody was waiting on it).
95 * The default case (no contention) will result in NO
96 * jumps for both down() and up().
97 */
98static inline void up(struct semaphore * sem)
99{
100 __up_op(sem, __up_wakeup);
101}
102
103#endif