HelenOS Kernel (amd64): kernel/generic/include/synch/rwlock.h Source File

00001 /*
00002  * Copyright (C) 2001-2004 Jakub Jermar
00003  * All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions
00007  * are met:
00008  *
00009  * - Redistributions of source code must retain the above copyright
00010  *   notice, this list of conditions and the following disclaimer.
00011  * - Redistributions in binary form must reproduce the above copyright
00012  *   notice, this list of conditions and the following disclaimer in the
00013  *   documentation and/or other materials provided with the distribution.
00014  * - The name of the author may not be used to endorse or promote products
00015  *   derived from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
00018  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00019  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00020  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
00021  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
00022  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
00023  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
00024  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00025  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
00026  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00027  */
00028 
00035 #ifndef __RWLOCK_H__
00036 #define __RWLOCK_H__
00037 
00038 #include <arch/types.h>
00039 #include <typedefs.h>
00040 #include <synch/mutex.h>
00041 #include <synch/synch.h>
00042 #include <synch/spinlock.h>
00043 
00044 enum rwlock_type {
00045         RWLOCK_NONE,
00046         RWLOCK_READER,
00047         RWLOCK_WRITER
00048 };
00049 
00050 struct rwlock {
00051         SPINLOCK_DECLARE(lock);
00052         mutex_t exclusive;      
00053         count_t readers_in;     
00054 };
00055 
00056 #define rwlock_write_lock(rwl) \
00057         _rwlock_write_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NONE)
00058 #define rwlock_read_lock(rwl) \
00059         _rwlock_read_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NONE)
00060 #define rwlock_write_trylock(rwl) \
00061         _rwlock_write_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NON_BLOCKING)
00062 #define rwlock_read_trylock(rwl) \
00063         _rwlock_read_lock_timeout((rwl),SYNCH_NO_TIMEOUT,SYNCH_FLAGS_NON_BLOCKING)
00064 #define rwlock_write_lock_timeout(rwl,usec) \
00065         _rwlock_write_lock_timeout((rwl),(usec),SYNCH_FLAGS_NONE)
00066 #define rwlock_read_lock_timeout(rwl,usec) \
00067         _rwlock_read_lock_timeout((rwl),(usec),SYNCH_FLAGS_NONE)
00068 
00069 extern void rwlock_initialize(rwlock_t *rwl);
00070 extern void rwlock_read_unlock(rwlock_t *rwl);
00071 extern void rwlock_write_unlock(rwlock_t *rwl);
00072 extern int _rwlock_read_lock_timeout(rwlock_t *rwl, __u32 usec, int flags);
00073 extern int _rwlock_write_lock_timeout(rwlock_t *rwl, __u32 usec, int flags);
00074 
00075 #endif
00076 
00077