lock.h revision 1.13
1 1.13 pk /* $NetBSD: lock.h,v 1.13 2003/11/16 11:22:30 pk Exp $ */ 2 1.1 pk 3 1.1 pk /*- 4 1.4 thorpej * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc. 5 1.1 pk * All rights reserved. 6 1.1 pk * 7 1.1 pk * This code is derived from software contributed to The NetBSD Foundation 8 1.1 pk * by Paul Kranenburg. 9 1.1 pk * 10 1.1 pk * Redistribution and use in source and binary forms, with or without 11 1.1 pk * modification, are permitted provided that the following conditions 12 1.1 pk * are met: 13 1.1 pk * 1. Redistributions of source code must retain the above copyright 14 1.1 pk * notice, this list of conditions and the following disclaimer. 15 1.1 pk * 2. Redistributions in binary form must reproduce the above copyright 16 1.1 pk * notice, this list of conditions and the following disclaimer in the 17 1.1 pk * documentation and/or other materials provided with the distribution. 18 1.1 pk * 3. All advertising materials mentioning features or use of this software 19 1.1 pk * must display the following acknowledgement: 20 1.1 pk * This product includes software developed by the NetBSD 21 1.1 pk * Foundation, Inc. and its contributors. 22 1.1 pk * 4. Neither the name of The NetBSD Foundation nor the names of its 23 1.1 pk * contributors may be used to endorse or promote products derived 24 1.1 pk * from this software without specific prior written permission. 25 1.1 pk * 26 1.1 pk * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 1.1 pk * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 1.1 pk * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 1.1 pk * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 1.1 pk * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 1.1 pk * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 1.1 pk * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 1.1 pk * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 1.1 pk * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 1.1 pk * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 1.1 pk * POSSIBILITY OF SUCH DAMAGE. 37 1.1 pk */ 38 1.1 pk 39 1.1 pk #ifndef _MACHINE_LOCK_H 40 1.1 pk #define _MACHINE_LOCK_H 41 1.1 pk 42 1.1 pk /* 43 1.1 pk * Machine dependent spin lock operations. 44 1.1 pk */ 45 1.5 thorpej 46 1.7 thorpej /* XXX So we can expose this to userland. */ 47 1.10 hannken #ifdef __lint__ 48 1.10 hannken #define __ldstub(__addr) (__addr) 49 1.10 hannken #else /* !__lint__ */ 50 1.7 thorpej #define __ldstub(__addr) \ 51 1.7 thorpej ({ \ 52 1.8 pk int __v; \ 53 1.7 thorpej \ 54 1.7 thorpej __asm __volatile("ldstub [%1],%0" \ 55 1.7 thorpej : "=r" (__v) \ 56 1.7 thorpej : "r" (__addr) \ 57 1.7 thorpej : "memory"); \ 58 1.7 thorpej \ 59 1.7 thorpej __v; \ 60 1.7 thorpej }) 61 1.10 hannken #endif /* __lint__ */ 62 1.7 thorpej 63 1.9 thorpej static __inline void __cpu_simple_lock_init __P((__cpu_simple_lock_t *)) 64 1.7 thorpej __attribute__((__unused__)); 65 1.9 thorpej static __inline void __cpu_simple_lock __P((__cpu_simple_lock_t *)) 66 1.7 thorpej __attribute__((__unused__)); 67 1.9 thorpej static __inline int __cpu_simple_lock_try __P((__cpu_simple_lock_t *)) 68 1.7 thorpej __attribute__((__unused__)); 69 1.9 thorpej static __inline void __cpu_simple_unlock __P((__cpu_simple_lock_t *)) 70 1.7 thorpej __attribute__((__unused__)); 71 1.7 thorpej 72 1.12 pk #if __SIMPLELOCK_UNLOCKED != 0 73 1.12 pk #error __SIMPLELOCK_UNLOCKED must be 0 for this implementation 74 1.12 pk #endif 75 1.12 pk 76 1.7 thorpej static __inline void 77 1.9 thorpej __cpu_simple_lock_init(__cpu_simple_lock_t *alp) 78 1.1 pk { 79 1.2 pk 80 1.7 thorpej *alp = __SIMPLELOCK_UNLOCKED; 81 1.1 pk } 82 1.1 pk 83 1.7 thorpej static __inline void 84 1.9 thorpej __cpu_simple_lock(__cpu_simple_lock_t *alp) 85 1.1 pk { 86 1.2 pk 87 1.2 pk /* 88 1.7 thorpej * If someone else holds the lock use simple reads until it 89 1.7 thorpej * is released, then retry the atomic operation. This reduces 90 1.7 thorpej * memory bus contention because the cache-coherency logic 91 1.7 thorpej * does not have to broadcast invalidates on the lock while 92 1.7 thorpej * we spin on it. 93 1.2 pk */ 94 1.7 thorpej while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) { 95 1.7 thorpej while (*alp != __SIMPLELOCK_UNLOCKED) 96 1.7 thorpej /* spin */ ; 97 1.2 pk } 98 1.1 pk } 99 1.1 pk 100 1.7 thorpej static __inline int 101 1.9 thorpej __cpu_simple_lock_try(__cpu_simple_lock_t *alp) 102 1.1 pk { 103 1.2 pk 104 1.7 thorpej return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED); 105 1.1 pk } 106 1.1 pk 107 1.7 thorpej static __inline void 108 1.9 thorpej __cpu_simple_unlock(__cpu_simple_lock_t *alp) 109 1.1 pk { 110 1.2 pk 111 1.12 pk /* 112 1.13 pk * Insert compiler barrier to prevent instruction re-ordering 113 1.13 pk * around the lock release. 114 1.12 pk */ 115 1.13 pk __insn_barrier(); 116 1.13 pk *alp = __SIMPLELOCK_UNLOCKED; 117 1.1 pk } 118 1.1 pk 119 1.1 pk #endif /* _MACHINE_LOCK_H */ 120
Indexes created Mon Sep 22 21:09:42 GMT 2025