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/*
* SMP- and interrupt-safe semaphores..
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* (C) Copyright 1996 Linus Torvalds, Ralf Baechle
*/
#ifndef __ASM_MIPS_SEMAPHORE_H
#define __ASM_MIPS_SEMAPHORE_H
#include <asm/atomic.h>
struct semaphore {
atomic_t count;
atomic_t waking;
struct wait_queue * wait;
};
#define MUTEX ((struct semaphore) { ATOMIC_INIT(1), ATOMIC_INIT(0), NULL })
#define MUTEX_LOCKED ((struct semaphore) { ATOMIC_INIT(0), ATOMIC_INIT(0), NULL })
extern void __down(struct semaphore * sem);
extern int __down_interruptible(struct semaphore * sem);
extern void __up(struct semaphore * sem);
#define sema_init(sem, val) atomic_set(&((sem)->count), val)
/*
* These two _must_ execute atomically wrt each other.
*
* This is trivially done with load_locked/store_cond,
* which we have. Let the rest of the losers suck eggs.
*/
static inline void wake_one_more(struct semaphore * sem)
{
atomic_inc(&sem->waking);
}
static inline int waking_non_zero(struct semaphore *sem)
{
int ret, tmp;
__asm__ __volatile__(
"1:\tll\t%1,%2\n"
"blez\t%1,2f\n\t"
"subu\t%0,%1,1\n\t"
"sc\t%0,%2\n\t"
"beqz\t%0,1b\n\t"
"2:"
".text"
: "=r"(ret), "=r"(tmp), "=m"(__atomic_fool_gcc(&sem->waking))
: "0"(0));
return ret;
}
extern inline void down(struct semaphore * sem)
{
if (atomic_dec_return(&sem->count) < 0)
__down(sem);
}
extern inline int down_interruptible(struct semaphore * sem)
{
int ret = 0;
if (atomic_dec_return(&sem->count) < 0)
ret = __down_interruptible(sem);
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 (atomic_inc_return(&sem->count) <= 0)
__up(sem);
}
#endif /* __ASM_MIPS_SEMAPHORE_H */
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