109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
/*
|
|
* 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.
|
|
*
|
|
* Copyright (C) 1996 Linus Torvalds
|
|
* Copyright (C) 1998, 99, 2000, 01, 04 Ralf Baechle
|
|
* Copyright (C) 1999, 2000, 01 Silicon Graphics, Inc.
|
|
* Copyright (C) 2000, 01 MIPS Technologies, Inc.
|
|
*
|
|
* In all honesty, little of the old MIPS code left - the PPC64 variant was
|
|
* just looking nice and portable so I ripped it. Credits to whoever wrote
|
|
* it.
|
|
*/
|
|
#ifndef __ASM_SEMAPHORE_H
|
|
#define __ASM_SEMAPHORE_H
|
|
|
|
/*
|
|
* Remove spinlock-based RW semaphores; RW semaphore definitions are
|
|
* now in rwsem.h and we use the generic lib/rwsem.c implementation.
|
|
* Rework semaphores to use atomic_dec_if_positive.
|
|
* -- Paul Mackerras (paulus@samba.org)
|
|
*/
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
#include <asm/atomic.h>
|
|
#include <asm/system.h>
|
|
#include <linux/wait.h>
|
|
#include <linux/rwsem.h>
|
|
|
|
struct semaphore {
|
|
/*
|
|
* Note that any negative value of count is equivalent to 0,
|
|
* but additionally indicates that some process(es) might be
|
|
* sleeping on `wait'.
|
|
*/
|
|
atomic_t count;
|
|
wait_queue_head_t wait;
|
|
};
|
|
|
|
#define __SEMAPHORE_INITIALIZER(name, n) \
|
|
{ \
|
|
.count = ATOMIC_INIT(n), \
|
|
.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
|
|
}
|
|
|
|
#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
|
|
struct semaphore name = __SEMAPHORE_INITIALIZER(name, count)
|
|
|
|
#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
|
|
|
|
static inline void sema_init(struct semaphore *sem, int val)
|
|
{
|
|
atomic_set(&sem->count, val);
|
|
init_waitqueue_head(&sem->wait);
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
extern void __down(struct semaphore * sem);
|
|
extern int __down_interruptible(struct semaphore * sem);
|
|
extern void __up(struct semaphore * sem);
|
|
|
|
static inline void down(struct semaphore * sem)
|
|
{
|
|
might_sleep();
|
|
|
|
/*
|
|
* Try to get the semaphore, take the slow path if we fail.
|
|
*/
|
|
if (unlikely(atomic_dec_return(&sem->count) < 0))
|
|
__down(sem);
|
|
}
|
|
|
|
static inline int down_interruptible(struct semaphore * sem)
|
|
{
|
|
int ret = 0;
|
|
|
|
might_sleep();
|
|
|
|
if (unlikely(atomic_dec_return(&sem->count) < 0))
|
|
ret = __down_interruptible(sem);
|
|
return ret;
|
|
}
|
|
|
|
static inline int down_trylock(struct semaphore * sem)
|
|
{
|
|
return atomic_dec_if_positive(&sem->count) < 0;
|
|
}
|
|
|
|
static inline void up(struct semaphore * sem)
|
|
{
|
|
if (unlikely(atomic_inc_return(&sem->count) <= 0))
|
|
__up(sem);
|
|
}
|
|
|
|
#endif /* __KERNEL__ */
|
|
|
|
#endif /* __ASM_SEMAPHORE_H */
|