projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* |
| 2 | * This file is subject to the terms and conditions of the GNU General Public | |
| 3 | * License. See the file "COPYING" in the main directory of this archive | |
| 4 | * for more details. | |
| 5 | * | |
| 6 | * Copyright (C) 1996 Linus Torvalds | |
| 7 | * Copyright (C) 1998, 99, 2000, 01, 04 Ralf Baechle | |
| 8 | * Copyright (C) 1999, 2000, 01 Silicon Graphics, Inc. | |
| 9 | * Copyright (C) 2000, 01 MIPS Technologies, Inc. | |
| 10 | * | |
| 11 | * In all honesty, little of the old MIPS code left - the PPC64 variant was | |
| 12 | * just looking nice and portable so I ripped it. Credits to whoever wrote | |
| 13 | * it. | |
| 14 | */ | |
| 15 | #ifndef __ASM_SEMAPHORE_H | |
| 16 | #define __ASM_SEMAPHORE_H | |
| 17 | ||
| 18 | /* | |
| 19 | * Remove spinlock-based RW semaphores; RW semaphore definitions are | |
| 20 | * now in rwsem.h and we use the generic lib/rwsem.c implementation. | |
| 21 | * Rework semaphores to use atomic_dec_if_positive. | |
| 22 | * -- Paul Mackerras (paulus@samba.org) | |
| 23 | */ | |
| 24 | ||
| 25 | #ifdef __KERNEL__ | |
| 26 | ||
| 27 | #include <asm/atomic.h> | |
| 28 | #include <asm/system.h> | |
| 29 | #include <linux/wait.h> | |
| 30 | #include <linux/rwsem.h> | |
| 31 | ||
| 32 | struct semaphore { | |
| 33 | /* | |
| 34 | * Note that any negative value of count is equivalent to 0, | |
| 35 | * but additionally indicates that some process(es) might be | |
| 36 | * sleeping on `wait'. | |
| 37 | */ | |
| 38 | atomic_t count; | |
| 39 | wait_queue_head_t wait; | |
| 40 | }; | |
| 41 | ||
| 42 | #define __SEMAPHORE_INITIALIZER(name, n) \ | |
| 43 | { \ | |
| 44 | .count = ATOMIC_INIT(n), \ | |
| 45 | .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ | |
| 46 | } | |
| 47 | ||
| 48 | #define __MUTEX_INITIALIZER(name) \ | |
| 49 | __SEMAPHORE_INITIALIZER(name, 1) | |
| 50 | ||
| 51 | #define __DECLARE_SEMAPHORE_GENERIC(name, count) \ | |
| 52 | struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) | |
| 53 | ||
| 54 | #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1) | |
| 55 | #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name, 0) | |
| 56 | ||
| 57 | static inline void sema_init (struct semaphore *sem, int val) | |
| 58 | { | |
| 59 | atomic_set(&sem->count, val); | |
| 60 | init_waitqueue_head(&sem->wait); | |
| 61 | } | |
| 62 | ||
| 63 | static inline void init_MUTEX (struct semaphore *sem) | |
| 64 | { | |
| 65 | sema_init(sem, 1); | |
| 66 | } | |
| 67 | ||
| 68 | static inline void init_MUTEX_LOCKED (struct semaphore *sem) | |
| 69 | { | |
| 70 | sema_init(sem, 0); | |
| 71 | } | |
| 72 | ||
| 73 | extern void __down(struct semaphore * sem); | |
| 74 | extern int __down_interruptible(struct semaphore * sem); | |
| 75 | extern void __up(struct semaphore * sem); | |
| 76 | ||
| 77 | static inline void down(struct semaphore * sem) | |
| 78 | { | |
| 79 | might_sleep(); | |
| 80 | ||
| 81 | /* | |
| 82 | * Try to get the semaphore, take the slow path if we fail. | |
| 83 | */ | |
| 84 | if (unlikely(atomic_dec_return(&sem->count) < 0)) | |
| 85 | __down(sem); | |
| 86 | } | |
| 87 | ||
| 88 | static inline int down_interruptible(struct semaphore * sem) | |
| 89 | { | |
| 90 | int ret = 0; | |
| 91 | ||
| 92 | might_sleep(); | |
| 93 | ||
| 94 | if (unlikely(atomic_dec_return(&sem->count) < 0)) | |
| 95 | ret = __down_interruptible(sem); | |
| 96 | return ret; | |
| 97 | } | |
| 98 | ||
| 99 | static inline int down_trylock(struct semaphore * sem) | |
| 100 | { | |
| 101 | return atomic_dec_if_positive(&sem->count) < 0; | |
| 102 | } | |
| 103 | ||
| 104 | static inline void up(struct semaphore * sem) | |
| 105 | { | |
| 106 | if (unlikely(atomic_inc_return(&sem->count) <= 0)) | |
| 107 | __up(sem); | |
| 108 | } | |
| 109 | ||
| 110 | #endif /* __KERNEL__ */ | |
| 111 | ||
| 112 | #endif /* __ASM_SEMAPHORE_H */ |