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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#ifndef __ASM_SH_SEMAPHORE_H
2#define __ASM_SH_SEMAPHORE_H
3
4#include <linux/linkage.h>
5
6#ifdef __KERNEL__
7/*
8 * SMP- and interrupt-safe semaphores.
9 *
10 * (C) Copyright 1996 Linus Torvalds
11 *
12 * SuperH verison by Niibe Yutaka
13 * (Currently no asm implementation but generic C code...)
14 */
15
16#include <linux/spinlock.h>
17#include <linux/rwsem.h>
18#include <linux/wait.h>
19
20#include <asm/system.h>
21#include <asm/atomic.h>
22
23struct semaphore {
24 atomic_t count;
25 int sleepers;
26 wait_queue_head_t wait;
27};
28
29#define __SEMAPHORE_INITIALIZER(name, n) \
30{ \
31 .count = ATOMIC_INIT(n), \
32 .sleepers = 0, \
33 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
34}
35
36#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
37 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
38
39#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
40#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
41
42static inline void sema_init (struct semaphore *sem, int val)
43{
44/*
45 * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
46 *
47 * i'd rather use the more flexible initialization above, but sadly
48 * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
49 */
50 atomic_set(&sem->count, val);
51 sem->sleepers = 0;
52 init_waitqueue_head(&sem->wait);
53}
54
55static inline void init_MUTEX (struct semaphore *sem)
56{
57 sema_init(sem, 1);
58}
59
60static inline void init_MUTEX_LOCKED (struct semaphore *sem)
61{
62 sema_init(sem, 0);
63}
64
65#if 0
66asmlinkage void __down_failed(void /* special register calling convention */);
67asmlinkage int __down_failed_interruptible(void /* params in registers */);
68asmlinkage int __down_failed_trylock(void /* params in registers */);
69asmlinkage void __up_wakeup(void /* special register calling convention */);
70#endif
71
72asmlinkage void __down(struct semaphore * sem);
73asmlinkage int __down_interruptible(struct semaphore * sem);
74asmlinkage int __down_trylock(struct semaphore * sem);
75asmlinkage void __up(struct semaphore * sem);
76
77extern spinlock_t semaphore_wake_lock;
78
79static inline void down(struct semaphore * sem)
80{
81 might_sleep();
82 if (atomic_dec_return(&sem->count) < 0)
83 __down(sem);
84}
85
86static inline int down_interruptible(struct semaphore * sem)
87{
88 int ret = 0;
89
90 might_sleep();
91 if (atomic_dec_return(&sem->count) < 0)
92 ret = __down_interruptible(sem);
93 return ret;
94}
95
96static inline int down_trylock(struct semaphore * sem)
97{
98 int ret = 0;
99
100 if (atomic_dec_return(&sem->count) < 0)
101 ret = __down_trylock(sem);
102 return ret;
103}
104
105/*
106 * Note! This is subtle. We jump to wake people up only if
107 * the semaphore was negative (== somebody was waiting on it).
108 */
109static inline void up(struct semaphore * sem)
110{
111 if (atomic_inc_return(&sem->count) <= 0)
112 __up(sem);
113}
114
115#endif
116#endif /* __ASM_SH_SEMAPHORE_H */