Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * include/asm-s390/semaphore.h | |
3 | * | |
4 | * S390 version | |
5 | * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation | |
6 | * | |
7 | * Derived from "include/asm-i386/semaphore.h" | |
8 | * (C) Copyright 1996 Linus Torvalds | |
9 | */ | |
10 | ||
11 | #ifndef _S390_SEMAPHORE_H | |
12 | #define _S390_SEMAPHORE_H | |
13 | ||
14 | #include <asm/system.h> | |
15 | #include <asm/atomic.h> | |
16 | #include <linux/wait.h> | |
17 | #include <linux/rwsem.h> | |
18 | ||
19 | struct semaphore { | |
20 | /* | |
21 | * Note that any negative value of count is equivalent to 0, | |
22 | * but additionally indicates that some process(es) might be | |
23 | * sleeping on `wait'. | |
24 | */ | |
25 | atomic_t count; | |
26 | wait_queue_head_t wait; | |
27 | }; | |
28 | ||
29 | #define __SEMAPHORE_INITIALIZER(name,count) \ | |
30 | { ATOMIC_INIT(count), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) } | |
31 | ||
1da177e4 LT |
32 | #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ |
33 | struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) | |
34 | ||
35 | #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) | |
36 | #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) | |
37 | ||
38 | static inline void sema_init (struct semaphore *sem, int val) | |
39 | { | |
4ea2176d IM |
40 | atomic_set(&sem->count, val); |
41 | init_waitqueue_head(&sem->wait); | |
1da177e4 LT |
42 | } |
43 | ||
44 | static inline void init_MUTEX (struct semaphore *sem) | |
45 | { | |
46 | sema_init(sem, 1); | |
47 | } | |
48 | ||
49 | static inline void init_MUTEX_LOCKED (struct semaphore *sem) | |
50 | { | |
51 | sema_init(sem, 0); | |
52 | } | |
53 | ||
54 | asmlinkage void __down(struct semaphore * sem); | |
55 | asmlinkage int __down_interruptible(struct semaphore * sem); | |
56 | asmlinkage int __down_trylock(struct semaphore * sem); | |
57 | asmlinkage void __up(struct semaphore * sem); | |
58 | ||
59 | static inline void down(struct semaphore * sem) | |
60 | { | |
61 | might_sleep(); | |
62 | if (atomic_dec_return(&sem->count) < 0) | |
63 | __down(sem); | |
64 | } | |
65 | ||
66 | static inline int down_interruptible(struct semaphore * sem) | |
67 | { | |
68 | int ret = 0; | |
69 | ||
70 | might_sleep(); | |
71 | if (atomic_dec_return(&sem->count) < 0) | |
72 | ret = __down_interruptible(sem); | |
73 | return ret; | |
74 | } | |
75 | ||
76 | static inline int down_trylock(struct semaphore * sem) | |
77 | { | |
78 | int old_val, new_val; | |
79 | ||
80 | /* | |
81 | * This inline assembly atomically implements the equivalent | |
82 | * to the following C code: | |
83 | * old_val = sem->count.counter; | |
84 | * if ((new_val = old_val) > 0) | |
85 | * sem->count.counter = --new_val; | |
86 | * In the ppc code this is called atomic_dec_if_positive. | |
87 | */ | |
94c12cc7 MS |
88 | asm volatile( |
89 | " l %0,0(%3)\n" | |
90 | "0: ltr %1,%0\n" | |
91 | " jle 1f\n" | |
92 | " ahi %1,-1\n" | |
93 | " cs %0,%1,0(%3)\n" | |
94 | " jl 0b\n" | |
1da177e4 LT |
95 | "1:" |
96 | : "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter) | |
97 | : "a" (&sem->count.counter), "m" (sem->count.counter) | |
94c12cc7 | 98 | : "cc", "memory"); |
1da177e4 LT |
99 | return old_val <= 0; |
100 | } | |
101 | ||
102 | static inline void up(struct semaphore * sem) | |
103 | { | |
104 | if (atomic_inc_return(&sem->count) <= 0) | |
105 | __up(sem); | |
106 | } | |
107 | ||
108 | #endif |