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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 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 | /* * include/asm-s390/semaphore.h * * S390 version * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation * * Derived from "include/asm-i386/semaphore.h" * (C) Copyright 1996 Linus Torvalds */ #ifndef _S390_SEMAPHORE_H #define _S390_SEMAPHORE_H #include <asm/system.h> #include <asm/atomic.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,count) \ { ATOMIC_INIT(count), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) } #define __MUTEX_INITIALIZER(name) \ __SEMAPHORE_INITIALIZER(name,1) #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) static inline void sema_init (struct semaphore *sem, int val) { *sem = (struct semaphore) __SEMAPHORE_INITIALIZER((*sem),val); } 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); } asmlinkage void __down(struct semaphore * sem); asmlinkage int __down_interruptible(struct semaphore * sem); asmlinkage int __down_trylock(struct semaphore * sem); asmlinkage void __up(struct semaphore * sem); static inline void down(struct semaphore * sem) { might_sleep(); if (atomic_dec_return(&sem->count) < 0) __down(sem); } static inline int down_interruptible(struct semaphore * sem) { int ret = 0; might_sleep(); if (atomic_dec_return(&sem->count) < 0) ret = __down_interruptible(sem); return ret; } static inline int down_trylock(struct semaphore * sem) { int old_val, new_val; /* * This inline assembly atomically implements the equivalent * to the following C code: * old_val = sem->count.counter; * if ((new_val = old_val) > 0) * sem->count.counter = --new_val; * In the ppc code this is called atomic_dec_if_positive. */ __asm__ __volatile__ ( " l %0,0(%3)\n" "0: ltr %1,%0\n" " jle 1f\n" " ahi %1,-1\n" " cs %0,%1,0(%3)\n" " jl 0b\n" "1:" : "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter) : "a" (&sem->count.counter), "m" (sem->count.counter) : "cc", "memory" ); return old_val <= 0; } static inline void up(struct semaphore * sem) { if (atomic_inc_return(&sem->count) <= 0) __up(sem); } #endif |