1 /* $NetBSD: mutex.h,v 1.12 2008/04/28 20:23:39 martin 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 45 struct kmutex { 46 uintptr_t mtx_pad1; 47 }; 48 49 #else /* __MUTEX_PRIVATE */ 50 51 struct 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 /* 75 * MUTEX_RECEIVE: no memory barrier required; we're synchronizing against 76 * interrupts, not multiple processors. 77 */ 78 #define MUTEX_RECEIVE(mtx) /* nothing */ 79 80 /* 81 * MUTEX_GIVE: no memory barrier required; same reason. 82 */ 83 #define MUTEX_GIVE(mtx) /* nothing */ 84 85 #define MUTEX_CAS(p, o, n) (atomic_cas_ulong((p), (o), (n)) == (o)) 86 87 #endif /* __MUTEX_PRIVATE */ 88 89 #endif /* _VAX_MUTEX_H_ */ 90