04fc8bbcf5
DECLARE_MUTEX_LOCKED was used for semaphores used as completions and we've got rid of them. Well, except for one in libusual that the maintainer explicitly wants to keep as semaphore. So convert that useage to an explicit sema_init and kill of DECLARE_MUTEX_LOCKED so that new code is reminded to use a completion. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: "Satyam Sharma" <satyam.sharma@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
/*
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* SMP- and interrupt-safe semaphores.
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*
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* Copyright (C) 2006 Atmel Corporation
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*
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* Based on include/asm-i386/semaphore.h
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* Copyright (C) 1996 Linus Torvalds
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_AVR32_SEMAPHORE_H
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#define __ASM_AVR32_SEMAPHORE_H
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#include <linux/linkage.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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atomic_t count;
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int sleepers;
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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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atomic_set(&sem->count, val);
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sem->sleepers = 0;
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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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void __down(struct semaphore * sem);
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int __down_interruptible(struct semaphore * sem);
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void __up(struct semaphore * sem);
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/*
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* This is ugly, but we want the default case to fall through.
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* "__down_failed" is a special asm handler that calls the C
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* routine that actually waits. See arch/i386/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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might_sleep();
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if (unlikely(atomic_dec_return (&sem->count) < 0))
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__down (sem);
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}
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/*
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* Interruptible try to acquire a semaphore. If we obtained
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* it, return zero. If we were interrupted, returns -EINTR
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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 (unlikely(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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/*
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* Non-blockingly attempt to down() a semaphore.
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* Returns zero if we acquired it
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*/
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static inline int down_trylock(struct semaphore * sem)
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{
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return atomic_dec_if_positive(&sem->count) < 0;
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}
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/*
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* Note! This is subtle. We jump to wake people up only if
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* the semaphore was negative (== somebody was waiting on it).
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* The default case (no contention) will result in NO
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* jumps for both down() and up().
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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 (sem);
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}
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#endif /*__ASM_AVR32_SEMAPHORE_H */
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