/*
* Copyright (C) 2001-2004 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __RWLOCK_H__
#define __RWLOCK_H__
#include <arch/types.h>
#include <typedefs.h>
#include <synch/mutex.h>
#include <synch/synch.h>
enum rwlock_type {
RWLOCK_NONE,
RWLOCK_READER,
RWLOCK_WRITER
};
struct rwlock {
spinlock_t lock;
mutex_t exclusive; /**< Mutex for writers, readers can bypass it if readers_in is positive. */
count_t readers_in; /**< Number of readers in critical section. */
};
#define rwlock_write_lock(rwl) \
_rwlock_write_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_BLOCKING)
#define rwlock_read_lock(rwl) \
_rwlock_read_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_BLOCKING)
#define rwlock_write_trylock(rwl) \
_rwlock_write_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_NON_BLOCKING)
#define rwlock_read_trylock(rwl) \
_rwlock_read_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_NON_BLOCKING)
#define rwlock_write_lock_timeout(rwl,usec) \
_rwlock_write_lock_timeout((rwl),(usec),SYNCH_NON_BLOCKING)
#define rwlock_read_lock_timeout(rwl,usec) \
_rwlock_read_lock_timeout((rwl),(usec),SYNCH_NON_BLOCKING)
extern void rwlock_initialize(rwlock_t *rwl);
extern void rwlock_read_unlock(rwlock_t *rwl);
extern void rwlock_write_unlock(rwlock_t *rwl);
extern int _rwlock_read_lock_timeout(rwlock_t *rwl, __u32 usec, int trylock);
extern int _rwlock_write_lock_timeout(rwlock_t *rwl, __u32 usec, int trylock);
#endif