mutex.h revision 1.16 
1/*	$NetBSD: mutex.h,v 1.16 2021/08/25 04:13:42 thorpej Exp $	*/
2
3/*-
4 * Copyright (c) 2002, 2007 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 _VAX_MUTEX_H_
33#define	_VAX_MUTEX_H_
34
35/*
36 * The VAX mutex implementation is troublesome, because VAX lacks a
37 * compare-and-swap operation.
38 *
39 * So we emulate compare-and-swap by raising IPL to lock out interrupts
40 * and (if MP) using BBSSI/BBCCI to lock out the other processors.
41 */
42
43#ifndef __MUTEX_PRIVATE
44
45struct kmutex {
46	uintptr_t	mtx_pad1;
47};
48
49#else	/* __MUTEX_PRIVATE */
50
51struct kmutex {
52	union {
53		/* Adaptive mutex */
54		volatile uintptr_t	mtxa_owner;	/* 0-3 */
55
56		/* Spin mutex */
57		struct {
58			volatile uint8_t	mtxs_dummy;
59			ipl_cookie_t		mtxs_ipl;
60			__cpu_simple_lock_t	mtxs_lock;
61			volatile uint8_t	mtxs_unused;
62		} s;
63	} u;
64};
65
66#define	mtx_owner		u.mtxa_owner
67#define	mtx_ipl			u.s.mtxs_ipl
68#define	mtx_lock		u.s.mtxs_lock
69
70#define	__HAVE_MUTEX_STUBS		1
71#define	__HAVE_SPIN_MUTEX_STUBS		1
72#define	__HAVE_SIMPLE_MUTEXES		1
73
74#endif	/* __MUTEX_PRIVATE */
75
76#endif /* _VAX_MUTEX_H_ */
77