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Linux kernel mirror (for testing)
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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
41static inline void sema_init (struct semaphore *sem, int val)
42{
43/*
44 * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
45 *
46 * i'd rather use the more flexible initialization above, but sadly
47 * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
48 */
49 atomic_set(&sem->count, val);
50 sem->sleepers = 0;
51 init_waitqueue_head(&sem->wait);
52}
53
54static inline void init_MUTEX (struct semaphore *sem)
55{
56 sema_init(sem, 1);
57}
58
59static inline void init_MUTEX_LOCKED (struct semaphore *sem)
60{
61 sema_init(sem, 0);
62}
63
64#if 0
65asmlinkage void __down_failed(void /* special register calling convention */);
66asmlinkage int __down_failed_interruptible(void /* params in registers */);
67asmlinkage int __down_failed_trylock(void /* params in registers */);
68asmlinkage void __up_wakeup(void /* special register calling convention */);
69#endif
70
71asmlinkage void __down(struct semaphore * sem);
72asmlinkage int __down_interruptible(struct semaphore * sem);
73asmlinkage int __down_trylock(struct semaphore * sem);
74asmlinkage void __up(struct semaphore * sem);
75
76extern spinlock_t semaphore_wake_lock;
77
78static inline void down(struct semaphore * sem)
79{
80 might_sleep();
81 if (atomic_dec_return(&sem->count) < 0)
82 __down(sem);
83}
84
85static inline int down_interruptible(struct semaphore * sem)
86{
87 int ret = 0;
88
89 might_sleep();
90 if (atomic_dec_return(&sem->count) < 0)
91 ret = __down_interruptible(sem);
92 return ret;
93}
94
95static inline int down_trylock(struct semaphore * sem)
96{
97 int ret = 0;
98
99 if (atomic_dec_return(&sem->count) < 0)
100 ret = __down_trylock(sem);
101 return ret;
102}
103
104/*
105 * Note! This is subtle. We jump to wake people up only if
106 * the semaphore was negative (== somebody was waiting on it).
107 */
108static inline void up(struct semaphore * sem)
109{
110 if (atomic_inc_return(&sem->count) <= 0)
111 __up(sem);
112}
113
114#endif
115#endif /* __ASM_SH_SEMAPHORE_H */