[deliverable/linux.git] / include / asm-mips / semaphore.h

/*
 * 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 */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This file is subject to the terms and conditions of the GNU General Public
	3	* License. See the file "COPYING" in the main directory of this archive
	4	* for more details.
	5	*
	6	* Copyright (C) 1996 Linus Torvalds
	7	* Copyright (C) 1998, 99, 2000, 01, 04 Ralf Baechle
	8	* Copyright (C) 1999, 2000, 01 Silicon Graphics, Inc.
	9	* Copyright (C) 2000, 01 MIPS Technologies, Inc.
	10	*
	11	* In all honesty, little of the old MIPS code left - the PPC64 variant was
	12	* just looking nice and portable so I ripped it. Credits to whoever wrote
	13	* it.
	14	*/
	15	#ifndef __ASM_SEMAPHORE_H
	16	#define __ASM_SEMAPHORE_H
	17
	18	/*
	19	* Remove spinlock-based RW semaphores; RW semaphore definitions are
	20	* now in rwsem.h and we use the generic lib/rwsem.c implementation.
	21	* Rework semaphores to use atomic_dec_if_positive.
	22	* -- Paul Mackerras (paulus@samba.org)
	23	*/
	24
	25	#ifdef __KERNEL__
	26
	27	#include <asm/atomic.h>
	28	#include <asm/system.h>
	29	#include <linux/wait.h>
	30	#include <linux/rwsem.h>
	31
	32	struct semaphore {
	33	/*
	34	* Note that any negative value of count is equivalent to 0,
	35	* but additionally indicates that some process(es) might be
	36	* sleeping on `wait'.
	37	*/
	38	atomic_t count;
	39	wait_queue_head_t wait;
	40	};
	41
	42	#define __SEMAPHORE_INITIALIZER(name, n) \
	43	{ \
	44	.count = ATOMIC_INIT(n), \
	45	.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
	46	}
	47
1da177e4	48	#define __DECLARE_SEMAPHORE_GENERIC(name, count) \
21a151d8	49	struct semaphore name = __SEMAPHORE_INITIALIZER(name, count)
1da177e4 LT	50
1da177e4 LT	51	#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1)
1da177e4	52
49a89efb	53	static inline void sema_init(struct semaphore *sem, int val)
1da177e4 LT	54	{
	55	atomic_set(&sem->count, val);
	56	init_waitqueue_head(&sem->wait);
	57	}
	58
49a89efb	59	static inline void init_MUTEX(struct semaphore *sem)
1da177e4 LT	60	{
	61	sema_init(sem, 1);
	62	}
	63
49a89efb	64	static inline void init_MUTEX_LOCKED(struct semaphore *sem)
1da177e4 LT	65	{
	66	sema_init(sem, 0);
	67	}
	68
	69	extern void __down(struct semaphore * sem);
	70	extern int __down_interruptible(struct semaphore * sem);
	71	extern void __up(struct semaphore * sem);
	72
	73	static inline void down(struct semaphore * sem)
	74	{
	75	might_sleep();
	76
	77	/*
	78	* Try to get the semaphore, take the slow path if we fail.
	79	*/
	80	if (unlikely(atomic_dec_return(&sem->count) < 0))
	81	__down(sem);
	82	}
	83
	84	static inline int down_interruptible(struct semaphore * sem)
	85	{
	86	int ret = 0;
	87
	88	might_sleep();
	89
	90	if (unlikely(atomic_dec_return(&sem->count) < 0))
	91	ret = __down_interruptible(sem);
	92	return ret;
	93	}
	94
	95	static inline int down_trylock(struct semaphore * sem)
	96	{
	97	return atomic_dec_if_positive(&sem->count) < 0;
	98	}
	99
	100	static inline void up(struct semaphore * sem)
	101	{
	102	if (unlikely(atomic_inc_return(&sem->count) <= 0))
	103	__up(sem);
	104	}
	105
	106	#endif /* __KERNEL__ */
	107
	108	#endif /* __ASM_SEMAPHORE_H */