1 /* $NetBSD: rwlock.h,v 1.3 2007/11/21 10:19:09 yamt 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #ifndef _VAX_RWLOCK_H_ 40 #define _VAX_RWLOCK_H_ 41 42 struct krwlock { 43 volatile uintptr_t rw_owner; 44 __cpu_simple_lock_t rw_lock; 45 unsigned int rw_dodebug : 24; 46 }; 47 48 #ifdef __RWLOCK_PRIVATE 49 50 #define RW_RECEIVE(rw) /* nothing */ 51 #define RW_GIVE(rw) /* nothing */ 52 53 bool _rw_cas(krwlock_t *rw, uintptr_t old, uintptr_t new); 54 55 /* 56 * RW_ACQUIRE(rw, old, new) 57 * Perform an atomic "compare and swap" operation and 58 * evaluate to true or false according to the success 59 * of the operation, such that: 60 * if (rw->rw_owner == old) { 61 * rw->rw_owner = new; 62 * return 1; 63 * } else 64 * return 0; 65 * Must be MP/interrupt atomic. 66 */ 67 #define RW_ACQUIRE(rw, old, new) _rw_cas(rw, old, new) 68 69 /* 70 * 71 * RW_RELEASE(rw, old, new) 72 * As above, but for releasing the lock. Must be 73 * MP/interrupt atomic. 74 */ 75 #define RW_RELEASE(rw, old, new) _rw_cas(rw, old, new) 76 77 /* 78 * RW_SET_WAITERS(rw, need_wait, set_wait) 79 * Set the has-waiters indication. If the needs-waiting 80 * condition becomes false, abort the operation. Must 81 * be MP/interrupt atomic. 82 */ 83 static inline bool 84 RW_SET_WAITERS(krwlock_t *rw, uintptr_t need, uintptr_t set) 85 { 86 uintptr_t old = rw->rw_owner; 87 if (old & need) 88 return _rw_cas(rw, old, old | set); 89 return false; 90 } 91 92 /* 93 * RW_SETID(rw, id) 94 * Set the debugging ID for the lock, an integer. Only 95 * used in the LOCKDEBUG case. 96 */ 97 static inline void 98 RW_SETDEBUG(krwlock_t *rw, bool dodebug) 99 { 100 rw->rw_dodebug = dodebug; 101 } 102 103 /* 104 * RW_GETID(rw) 105 * Get the debugging ID for the lock, an integer. Only 106 * used in the LOCKDEBUG case. 107 */ 108 static inline bool 109 RW_DEBUG_P(krwlock_t *rw) 110 { 111 return rw->rw_dodebug; 112 } 113 114 #endif /* __RWLOCK_PRIVATE */ 115 116 #endif /* _VAX_RWLOCK_H_ */ 117