blob: 48dd32e077499878e6f376011f9e69ff165fea1d (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
#ifndef _ASM_POWERPC_SEMAPHORE_H
#define _ASM_POWERPC_SEMAPHORE_H
/*
* Remove spinlock-based RW semaphores; RW semaphore definitions are
* now in rwsem.h and we use the generic lib/rwsem.c implementation.
* Rework semaphores to use atomic_dec_if_positive.
* -- Paul Mackerras (paulus@samba.org)
*/
#ifdef __KERNEL__
#include <asm/atomic.h>
#include <asm/system.h>
#include <linux/wait.h>
#include <linux/rwsem.h>
struct semaphore {
/*
* Note that any negative value of count is equivalent to 0,
* but additionally indicates that some process(es) might be
* sleeping on `wait'.
*/
atomic_t count;
wait_queue_head_t wait;
};
#define __SEMAPHORE_INITIALIZER(name, n) \
{ \
.count = ATOMIC_INIT(n), \
.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
}
#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
static inline void sema_init (struct semaphore *sem, int val)
{
atomic_set(&sem->count, val);
init_waitqueue_head(&sem->wait);
}
static inline void init_MUTEX (struct semaphore *sem)
{
sema_init(sem, 1);
}
static inline void init_MUTEX_LOCKED (struct semaphore *sem)
{
sema_init(sem, 0);
}
extern void __down(struct semaphore * sem);
extern int __down_interruptible(struct semaphore * sem);
extern void __up(struct semaphore * sem);
static inline void down(struct semaphore * sem)
{
might_sleep();
/*
* Try to get the semaphore, take the slow path if we fail.
*/
if (unlikely(atomic_dec_return(&sem->count) < 0))
__down(sem);
}
static inline int down_interruptible(struct semaphore * sem)
{
int ret = 0;
might_sleep();
if (unlikely(atomic_dec_return(&sem->count) < 0))
ret = __down_interruptible(sem);
return ret;
}
static inline int down_trylock(struct semaphore * sem)
{
return atomic_dec_if_positive(&sem->count) < 0;
}
static inline void up(struct semaphore * sem)
{
if (unlikely(atomic_inc_return(&sem->count) <= 0))
__up(sem);
}
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_SEMAPHORE_H */
|
