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Linux kernel mirror (for testing)
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kernel
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linux
1#ifndef _PPC_SEMAPHORE_H
2#define _PPC_SEMAPHORE_H
3
4/*
5 * Swiped from asm-sparc/semaphore.h and modified
6 * -- Cort (cort@cs.nmt.edu)
7 *
8 * Stole some rw spinlock-based semaphore stuff from asm-alpha/semaphore.h
9 * -- Ani Joshi (ajoshi@unixbox.com)
10 *
11 * Remove spinlock-based RW semaphores; RW semaphore definitions are
12 * now in rwsem.h and we use the generic lib/rwsem.c implementation.
13 * Rework semaphores to use atomic_dec_if_positive.
14 * -- Paul Mackerras (paulus@samba.org)
15 */
16
17#ifdef __KERNEL__
18
19#include <asm/atomic.h>
20#include <asm/system.h>
21#include <linux/wait.h>
22#include <linux/rwsem.h>
23
24struct semaphore {
25 /*
26 * Note that any negative value of count is equivalent to 0,
27 * but additionally indicates that some process(es) might be
28 * sleeping on `wait'.
29 */
30 atomic_t count;
31 wait_queue_head_t wait;
32};
33
34#define __SEMAPHORE_INITIALIZER(name, n) \
35{ \
36 .count = ATOMIC_INIT(n), \
37 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
38}
39
40#define __MUTEX_INITIALIZER(name) \
41 __SEMAPHORE_INITIALIZER(name, 1)
42
43#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
44 struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
45
46#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
47#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0)
48
49static inline void sema_init (struct semaphore *sem, int val)
50{
51 atomic_set(&sem->count, val);
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
65extern void __down(struct semaphore * sem);
66extern int __down_interruptible(struct semaphore * sem);
67extern void __up(struct semaphore * sem);
68
69extern inline void down(struct semaphore * sem)
70{
71 might_sleep();
72
73 /*
74 * Try to get the semaphore, take the slow path if we fail.
75 */
76 if (atomic_dec_return(&sem->count) < 0)
77 __down(sem);
78 smp_wmb();
79}
80
81extern inline int down_interruptible(struct semaphore * sem)
82{
83 int ret = 0;
84
85 might_sleep();
86
87 if (atomic_dec_return(&sem->count) < 0)
88 ret = __down_interruptible(sem);
89 smp_wmb();
90 return ret;
91}
92
93extern inline int down_trylock(struct semaphore * sem)
94{
95 int ret;
96
97 ret = atomic_dec_if_positive(&sem->count) < 0;
98 smp_wmb();
99 return ret;
100}
101
102extern inline void up(struct semaphore * sem)
103{
104 smp_wmb();
105 if (atomic_inc_return(&sem->count) <= 0)
106 __up(sem);
107}
108
109#endif /* __KERNEL__ */
110
111#endif /* !(_PPC_SEMAPHORE_H) */