rwlock.h revision 1.5 
1/*	$NetBSD: rwlock.h,v 1.5 2008/04/28 20:23:40 martin Exp $	*/
2
3/*-
4 * Copyright (c) 2002, 2006 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe and Andrew Doran.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#ifndef _X86_RWLOCK_H_
33#define	_X86_RWLOCK_H_
34
35struct krwlock {
36	volatile uintptr_t	rw_owner;
37};
38
39#ifdef __RWLOCK_PRIVATE
40
41#define	__HAVE_SIMPLE_RW_LOCKS		1
42#define	__HAVE_RW_STUBS			1
43
44/*
45 * RW_RECEIVE: no memory barrier required, as 'ret' implies a load fence.
46 */
47#define	RW_RECEIVE(rw)			/* nothing */
48
49/*
50 * RW_GIVE: no memory barrier required, as _lock_cas() will take care of it.
51 */
52#define	RW_GIVE(rw)			/* nothing */
53
54#define	RW_CAS(p, o, n)			\
55    (_atomic_cas_ulong((volatile unsigned long *)(p), (o), (n)) == (o))
56
57unsigned long	_atomic_cas_ulong(volatile unsigned long *,
58    unsigned long, unsigned long);
59
60#endif	/* __RWLOCK_PRIVATE */
61
62#endif /* _X86_RWLOCK_H_ */
63