lock.h revision 1.34
1 1.34 riastrad /* $NetBSD: lock.h,v 1.34 2022/02/13 13:41:17 riastradh Exp $ */ 2 1.1 pk 3 1.1 pk /*- 4 1.24 ad * Copyright (c) 1998, 1999, 2006 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 1.24 ad * by Paul Kranenburg and Andrew Doran. 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 * 19 1.1 pk * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 1.1 pk * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 1.1 pk * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 1.1 pk * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 1.1 pk * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 1.1 pk * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 1.1 pk * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 1.1 pk * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 1.1 pk * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 1.1 pk * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 1.1 pk * POSSIBILITY OF SUCH DAMAGE. 30 1.1 pk */ 31 1.1 pk 32 1.1 pk #ifndef _MACHINE_LOCK_H 33 1.1 pk #define _MACHINE_LOCK_H 34 1.1 pk 35 1.1 pk /* 36 1.1 pk * Machine dependent spin lock operations. 37 1.1 pk */ 38 1.5 thorpej 39 1.15 pk #if __SIMPLELOCK_UNLOCKED != 0 40 1.15 pk #error __SIMPLELOCK_UNLOCKED must be 0 for this implementation 41 1.15 pk #endif 42 1.15 pk 43 1.7 thorpej /* XXX So we can expose this to userland. */ 44 1.10 hannken #ifdef __lint__ 45 1.10 hannken #define __ldstub(__addr) (__addr) 46 1.10 hannken #else /* !__lint__ */ 47 1.22 perry static __inline int __ldstub(__cpu_simple_lock_t *addr); 48 1.22 perry static __inline int __ldstub(__cpu_simple_lock_t *addr) 49 1.14 mrg { 50 1.14 mrg int v; 51 1.14 mrg 52 1.20 perry __asm volatile("ldstub [%1],%0" 53 1.18 chs : "=&r" (v) 54 1.14 mrg : "r" (addr) 55 1.14 mrg : "memory"); 56 1.14 mrg 57 1.14 mrg return v; 58 1.14 mrg } 59 1.10 hannken #endif /* __lint__ */ 60 1.7 thorpej 61 1.23 uwe static __inline void __cpu_simple_lock_init(__cpu_simple_lock_t *) 62 1.7 thorpej __attribute__((__unused__)); 63 1.23 uwe static __inline int __cpu_simple_lock_try(__cpu_simple_lock_t *) 64 1.7 thorpej __attribute__((__unused__)); 65 1.23 uwe static __inline void __cpu_simple_unlock(__cpu_simple_lock_t *) 66 1.7 thorpej __attribute__((__unused__)); 67 1.17 pk #ifndef __CPU_SIMPLE_LOCK_NOINLINE 68 1.23 uwe static __inline void __cpu_simple_lock(__cpu_simple_lock_t *) 69 1.15 pk __attribute__((__unused__)); 70 1.15 pk #else 71 1.23 uwe extern void __cpu_simple_lock(__cpu_simple_lock_t *); 72 1.12 pk #endif 73 1.12 pk 74 1.29 skrll static __inline int 75 1.32 christos __SIMPLELOCK_LOCKED_P(const __cpu_simple_lock_t *__ptr) 76 1.29 skrll { 77 1.29 skrll return *__ptr == __SIMPLELOCK_LOCKED; 78 1.29 skrll } 79 1.29 skrll 80 1.29 skrll static __inline int 81 1.32 christos __SIMPLELOCK_UNLOCKED_P(const __cpu_simple_lock_t *__ptr) 82 1.29 skrll { 83 1.29 skrll return *__ptr == __SIMPLELOCK_UNLOCKED; 84 1.29 skrll } 85 1.29 skrll 86 1.29 skrll static __inline void 87 1.29 skrll __cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr) 88 1.29 skrll { 89 1.29 skrll *__ptr = __SIMPLELOCK_UNLOCKED; 90 1.29 skrll } 91 1.29 skrll 92 1.29 skrll static __inline void 93 1.29 skrll __cpu_simple_lock_set(__cpu_simple_lock_t *__ptr) 94 1.29 skrll { 95 1.29 skrll *__ptr = __SIMPLELOCK_LOCKED; 96 1.29 skrll } 97 1.29 skrll 98 1.22 perry static __inline void 99 1.9 thorpej __cpu_simple_lock_init(__cpu_simple_lock_t *alp) 100 1.1 pk { 101 1.2 pk 102 1.7 thorpej *alp = __SIMPLELOCK_UNLOCKED; 103 1.1 pk } 104 1.1 pk 105 1.17 pk #ifndef __CPU_SIMPLE_LOCK_NOINLINE 106 1.22 perry static __inline void 107 1.9 thorpej __cpu_simple_lock(__cpu_simple_lock_t *alp) 108 1.1 pk { 109 1.2 pk 110 1.2 pk /* 111 1.7 thorpej * If someone else holds the lock use simple reads until it 112 1.7 thorpej * is released, then retry the atomic operation. This reduces 113 1.7 thorpej * memory bus contention because the cache-coherency logic 114 1.7 thorpej * does not have to broadcast invalidates on the lock while 115 1.7 thorpej * we spin on it. 116 1.2 pk */ 117 1.7 thorpej while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) { 118 1.7 thorpej while (*alp != __SIMPLELOCK_UNLOCKED) 119 1.7 thorpej /* spin */ ; 120 1.2 pk } 121 1.34 riastrad 122 1.34 riastrad /* 123 1.34 riastrad * No memory barrier needed here to make this a load-acquire 124 1.34 riastrad * operation because LDSTUB already implies that. See SPARCv8 125 1.34 riastrad * Reference Manual, Appendix J.4 `Spin Locks', p. 271. 126 1.34 riastrad */ 127 1.1 pk } 128 1.17 pk #endif /* __CPU_SIMPLE_LOCK_NOINLINE */ 129 1.1 pk 130 1.22 perry static __inline int 131 1.9 thorpej __cpu_simple_lock_try(__cpu_simple_lock_t *alp) 132 1.1 pk { 133 1.2 pk 134 1.34 riastrad /* 135 1.34 riastrad * No memory barrier needed for LDSTUB to be a load-acquire -- 136 1.34 riastrad * see __cpu_simple_lock. 137 1.34 riastrad */ 138 1.7 thorpej return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED); 139 1.1 pk } 140 1.1 pk 141 1.22 perry static __inline void 142 1.9 thorpej __cpu_simple_unlock(__cpu_simple_lock_t *alp) 143 1.1 pk { 144 1.2 pk 145 1.12 pk /* 146 1.13 pk * Insert compiler barrier to prevent instruction re-ordering 147 1.13 pk * around the lock release. 148 1.34 riastrad * 149 1.34 riastrad * No memory barrier needed because we run the kernel in TSO. 150 1.34 riastrad * If we ran the kernel in PSO, this would require STBAR. 151 1.12 pk */ 152 1.13 pk __insn_barrier(); 153 1.13 pk *alp = __SIMPLELOCK_UNLOCKED; 154 1.1 pk } 155 1.1 pk 156 1.1 pk #endif /* _MACHINE_LOCK_H */ 157
Indexes created Sat Sep 27 22:09:54 GMT 2025