108 lines
2.4 KiB
C
108 lines
2.4 KiB
C
/*
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* include/asm-s390/semaphore.h
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*
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* S390 version
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* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
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*
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* Derived from "include/asm-i386/semaphore.h"
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* (C) Copyright 1996 Linus Torvalds
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*/
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#ifndef _S390_SEMAPHORE_H
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#define _S390_SEMAPHORE_H
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#include <asm/system.h>
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#include <asm/atomic.h>
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#include <linux/wait.h>
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#include <linux/rwsem.h>
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struct semaphore {
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/*
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* Note that any negative value of count is equivalent to 0,
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* but additionally indicates that some process(es) might be
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* sleeping on `wait'.
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*/
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atomic_t count;
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wait_queue_head_t wait;
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};
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#define __SEMAPHORE_INITIALIZER(name,count) \
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{ ATOMIC_INIT(count), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) }
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#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
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struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
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#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
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static inline void sema_init (struct semaphore *sem, int val)
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{
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atomic_set(&sem->count, val);
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init_waitqueue_head(&sem->wait);
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}
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static inline void init_MUTEX (struct semaphore *sem)
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{
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sema_init(sem, 1);
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}
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static inline void init_MUTEX_LOCKED (struct semaphore *sem)
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{
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sema_init(sem, 0);
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}
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asmlinkage void __down(struct semaphore * sem);
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asmlinkage int __down_interruptible(struct semaphore * sem);
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asmlinkage int __down_trylock(struct semaphore * sem);
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asmlinkage void __up(struct semaphore * sem);
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static inline void down(struct semaphore * sem)
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{
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might_sleep();
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if (atomic_dec_return(&sem->count) < 0)
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__down(sem);
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}
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static inline int down_interruptible(struct semaphore * sem)
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{
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int ret = 0;
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might_sleep();
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if (atomic_dec_return(&sem->count) < 0)
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ret = __down_interruptible(sem);
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return ret;
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}
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static inline int down_trylock(struct semaphore * sem)
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{
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int old_val, new_val;
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/*
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* This inline assembly atomically implements the equivalent
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* to the following C code:
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* old_val = sem->count.counter;
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* if ((new_val = old_val) > 0)
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* sem->count.counter = --new_val;
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* In the ppc code this is called atomic_dec_if_positive.
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*/
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asm volatile(
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" l %0,0(%3)\n"
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"0: ltr %1,%0\n"
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" jle 1f\n"
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" ahi %1,-1\n"
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" cs %0,%1,0(%3)\n"
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" jl 0b\n"
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"1:"
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: "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter)
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: "a" (&sem->count.counter), "m" (sem->count.counter)
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: "cc", "memory");
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return old_val <= 0;
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}
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static inline void up(struct semaphore * sem)
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{
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if (atomic_inc_return(&sem->count) <= 0)
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__up(sem);
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}
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#endif
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