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/* $Id$
*
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1996 Linus Torvalds
* Copyright (C) 1998, 1999 Ralf Baechle
* Copyright (C) 1999 Silicon Graphics, Inc.
*/
#ifndef _ASM_SEMAPHORE_H
#define _ASM_SEMAPHORE_H
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/spinlock.h>
#include <linux/wait.h>
struct semaphore {
atomic_t count;
atomic_t waking;
wait_queue_head_t wait;
#if WAITQUEUE_DEBUG
long __magic;
#endif
};
#if WAITQUEUE_DEBUG
# define __SEM_DEBUG_INIT(name) \
, (long)&(name).__magic
#else
# define __SEM_DEBUG_INIT(name)
#endif
#define __SEMAPHORE_INITIALIZER(name,count) \
{ ATOMIC_INIT(count), ATOMIC_INIT(0), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
__SEM_DEBUG_INIT(name) }
#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)
extern inline void sema_init (struct semaphore *sem, int val)
{
atomic_set(&sem->count, val);
atomic_set(&sem->waking, 0);
init_waitqueue_head(&sem->wait);
#if WAITQUEUE_DEBUG
sem->__magic = (long)&sem->__magic;
#endif
}
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);
extern inline void down(struct semaphore * sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
if (atomic_dec_return(&sem->count) < 0)
__down(sem);
}
extern inline int down_interruptible(struct semaphore * sem)
{
int ret = 0;
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
if (atomic_dec_return(&sem->count) < 0)
ret = __down_interruptible(sem);
return ret;
}
/*
* down_trylock returns 0 on success, 1 if we failed to get the lock.
*
* We must manipulate count and waking simultaneously and atomically.
* Do this by using ll/sc on the pair of 32-bit words.
*/
extern inline int down_trylock(struct semaphore * sem)
{
long ret, tmp, tmp2, sub;
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
#ifdef __MIPSEB__
__asm__ __volatile__("
.set mips3
0: lld %1, %4
dli %3, 0x0000000100000000
sltu %0, %1, $0
bltz %1, 1f
move %3, $0
1:
sltu %2, %1, $0
and %0, %0, %2
bnez %0, 2f
subu %0, %3
scd %1, %4
beqz %1, 0b
2:
.set mips0"
: "=&r"(ret), "=&r"(tmp), "=&r"(tmp2), "=&r"(sub)
: "m"(*sem)
: "memory");
#endif
#ifdef __MIPSEL__
#error "FIXME: down_trylock doesn't support little endian machines yet."
#endif
return ret;
}
/*
* Note! This is subtle. We jump to wake people up only if
* the semaphore was negative (== somebody was waiting on it).
*/
extern inline void up(struct semaphore * sem)
{
#if WAITQUEUE_DEBUG
CHECK_MAGIC(sem->__magic);
#endif
if (atomic_inc_return(&sem->count) <= 0)
__up(sem);
}
#endif /* _ASM_SEMAPHORE_H */
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