[deliverable/linux.git] / include / linux / rwsem.h

/* rwsem.h: R/W semaphores, public interface
 *
 * Written by David Howells (dhowells@redhat.com).
 * Derived from asm-i386/semaphore.h
 */

#ifndef _LINUX_RWSEM_H
#define _LINUX_RWSEM_H

#include <linux/linkage.h>

#ifdef __KERNEL__

#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/system.h>
#include <asm/atomic.h>

struct rw_semaphore;

#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
#include <linux/rwsem-spinlock.h> /* use a generic implementation */
#else
#include <asm/rwsem.h> /* use an arch-specific implementation */
#endif

/*
 * lock for reading
 */
static inline void down_read(struct rw_semaphore *sem)
{
	might_sleep();
	__down_read(sem);
}

/*
 * trylock for reading -- returns 1 if successful, 0 if contention
 */
static inline int down_read_trylock(struct rw_semaphore *sem)
{
	int ret;
	ret = __down_read_trylock(sem);
	return ret;
}

/*
 * lock for writing
 */
static inline void down_write(struct rw_semaphore *sem)
{
	might_sleep();
	__down_write(sem);
}

/*
 * trylock for writing -- returns 1 if successful, 0 if contention
 */
static inline int down_write_trylock(struct rw_semaphore *sem)
{
	int ret;
	ret = __down_write_trylock(sem);
	return ret;
}

/*
 * release a read lock
 */
static inline void up_read(struct rw_semaphore *sem)
{
	__up_read(sem);
}

/*
 * release a write lock
 */
static inline void up_write(struct rw_semaphore *sem)
{
	__up_write(sem);
}

/*
 * downgrade write lock to read lock
 */
static inline void downgrade_write(struct rw_semaphore *sem)
{
	__downgrade_write(sem);
}

#endif /* __KERNEL__ */
#endif /* _LINUX_RWSEM_H */
Commit	Line	Data
1da177e4 LT	1	/* rwsem.h: R/W semaphores, public interface
	2	*
	3	* Written by David Howells (dhowells@redhat.com).
	4	* Derived from asm-i386/semaphore.h
	5	*/
	6
	7	#ifndef _LINUX_RWSEM_H
	8	#define _LINUX_RWSEM_H
	9
	10	#include <linux/linkage.h>
	11
1da177e4 LT	12	#ifdef __KERNEL__
1da177e4 LT	13
1da177e4 LT	14	#include <linux/types.h>
	15	#include <linux/kernel.h>
	16	#include <asm/system.h>
	17	#include <asm/atomic.h>
	18
	19	struct rw_semaphore;
	20
	21	#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
	22	#include <linux/rwsem-spinlock.h> /* use a generic implementation */
	23	#else
	24	#include <asm/rwsem.h> /* use an arch-specific implementation */
	25	#endif
	26
1da177e4 LT	27	/*
	28	* lock for reading
	29	*/
	30	static inline void down_read(struct rw_semaphore *sem)
	31	{
	32	might_sleep();
1da177e4	33	__down_read(sem);
1da177e4 LT	34	}
	35
	36	/*
	37	* trylock for reading -- returns 1 if successful, 0 if contention
	38	*/
	39	static inline int down_read_trylock(struct rw_semaphore *sem)
	40	{
	41	int ret;
1da177e4	42	ret = __down_read_trylock(sem);
1da177e4 LT	43	return ret;
	44	}
	45
	46	/*
	47	* lock for writing
	48	*/
	49	static inline void down_write(struct rw_semaphore *sem)
	50	{
	51	might_sleep();
1da177e4	52	__down_write(sem);
1da177e4 LT	53	}
	54
	55	/*
	56	* trylock for writing -- returns 1 if successful, 0 if contention
	57	*/
	58	static inline int down_write_trylock(struct rw_semaphore *sem)
	59	{
	60	int ret;
1da177e4	61	ret = __down_write_trylock(sem);
1da177e4 LT	62	return ret;
	63	}
	64
	65	/*
	66	* release a read lock
	67	*/
	68	static inline void up_read(struct rw_semaphore *sem)
	69	{
1da177e4	70	__up_read(sem);
1da177e4 LT	71	}
	72
	73	/*
	74	* release a write lock
	75	*/
	76	static inline void up_write(struct rw_semaphore *sem)
	77	{
1da177e4	78	__up_write(sem);
1da177e4 LT	79	}
	80
	81	/*
	82	* downgrade write lock to read lock
	83	*/
	84	static inline void downgrade_write(struct rw_semaphore *sem)
	85	{
1da177e4	86	__downgrade_write(sem);
1da177e4 LT	87	}
	88
	89	#endif /* __KERNEL__ */
	90	#endif /* _LINUX_RWSEM_H */