150 строки
3.1 KiB
C
150 строки
3.1 KiB
C
#ifndef _ALPHA_SEMAPHORE_H
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#define _ALPHA_SEMAPHORE_H
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/*
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* SMP- and interrupt-safe semaphores..
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*
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* (C) Copyright 1996 Linus Torvalds
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* (C) Copyright 1996, 2000 Richard Henderson
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*/
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#include <asm/current.h>
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#include <asm/system.h>
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#include <asm/atomic.h>
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#include <linux/compiler.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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atomic_t count;
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wait_queue_head_t wait;
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};
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#define __SEMAPHORE_INITIALIZER(name, n) \
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{ \
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.count = ATOMIC_INIT(n), \
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.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \
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}
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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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/*
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* Logically,
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* *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
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* except that gcc produces better initializing by parts yet.
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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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extern void down(struct semaphore *);
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extern void __down_failed(struct semaphore *);
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extern int down_interruptible(struct semaphore *);
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extern int __down_failed_interruptible(struct semaphore *);
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extern int down_trylock(struct semaphore *);
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extern void up(struct semaphore *);
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extern void __up_wakeup(struct semaphore *);
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/*
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* Hidden out of line code is fun, but extremely messy. Rely on newer
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* compilers to do a respectable job with this. The contention cases
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* are handled out of line in arch/alpha/kernel/semaphore.c.
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*/
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static inline void __down(struct semaphore *sem)
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{
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long count;
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might_sleep();
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count = atomic_dec_return(&sem->count);
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if (unlikely(count < 0))
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__down_failed(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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long count;
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might_sleep();
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count = atomic_dec_return(&sem->count);
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if (unlikely(count < 0))
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return __down_failed_interruptible(sem);
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return 0;
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}
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/*
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* down_trylock returns 0 on success, 1 if we failed to get the lock.
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*/
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static inline int __down_trylock(struct semaphore *sem)
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{
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long ret;
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/* "Equivalent" C:
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do {
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ret = ldl_l;
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--ret;
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if (ret < 0)
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break;
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ret = stl_c = ret;
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} while (ret == 0);
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*/
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__asm__ __volatile__(
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"1: ldl_l %0,%1\n"
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" subl %0,1,%0\n"
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" blt %0,2f\n"
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" stl_c %0,%1\n"
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" beq %0,3f\n"
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" mb\n"
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"2:\n"
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".subsection 2\n"
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"3: br 1b\n"
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".previous"
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: "=&r" (ret), "=m" (sem->count)
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: "m" (sem->count));
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return ret < 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 (unlikely(atomic_inc_return(&sem->count) <= 0))
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__up_wakeup(sem);
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}
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#if !defined(CONFIG_DEBUG_SEMAPHORE)
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extern inline void down(struct semaphore *sem)
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{
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__down(sem);
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}
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extern inline int down_interruptible(struct semaphore *sem)
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{
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return __down_interruptible(sem);
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}
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extern inline int down_trylock(struct semaphore *sem)
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{
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return __down_trylock(sem);
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}
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extern inline void up(struct semaphore *sem)
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{
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__up(sem);
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}
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#endif
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#endif
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