1 /* $NetBSD: lock.h,v 1.2 2003/05/08 01:04:34 fvdl Exp $ */ 2 3 /*- 4 * Copyright (c) 2000 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. 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 /* 40 * Machine-dependent spin lock operations. 41 */ 42 43 #ifndef _I386_LOCK_H_ 44 #define _I386_LOCK_H_ 45 46 #if defined(_KERNEL_OPT) 47 #include "opt_lockdebug.h" 48 #endif 49 50 #include <machine/cpufunc.h> 51 52 typedef __volatile int __cpu_simple_lock_t; 53 54 #define __SIMPLELOCK_LOCKED 1 55 #define __SIMPLELOCK_UNLOCKED 0 56 57 /* 58 * compiler barrier: prevent reordering of instructions. 59 * XXX something similar will move to <sys/cdefs.h> 60 * or thereabouts. 61 * This prevents the compiler from reordering code around 62 * this "instruction", acting as a sequence point for code generation. 63 */ 64 65 #define __lockbarrier() __asm __volatile("": : :"memory") 66 67 #ifdef LOCKDEBUG 68 69 extern void __cpu_simple_lock_init __P((__cpu_simple_lock_t *)); 70 extern void __cpu_simple_lock __P((__cpu_simple_lock_t *)); 71 extern int __cpu_simple_lock_try __P((__cpu_simple_lock_t *)); 72 extern void __cpu_simple_unlock __P((__cpu_simple_lock_t *)); 73 74 #else 75 76 #include <machine/atomic.h> 77 78 static __inline void __cpu_simple_lock_init __P((__cpu_simple_lock_t *)) 79 __attribute__((__unused__)); 80 static __inline void __cpu_simple_lock __P((__cpu_simple_lock_t *)) 81 __attribute__((__unused__)); 82 static __inline int __cpu_simple_lock_try __P((__cpu_simple_lock_t *)) 83 __attribute__((__unused__)); 84 static __inline void __cpu_simple_unlock __P((__cpu_simple_lock_t *)) 85 __attribute__((__unused__)); 86 87 static __inline void 88 __cpu_simple_lock_init(__cpu_simple_lock_t *lockp) 89 { 90 91 *lockp = __SIMPLELOCK_UNLOCKED; 92 __lockbarrier(); 93 } 94 95 static __inline void 96 __cpu_simple_lock(__cpu_simple_lock_t *lockp) 97 { 98 99 while (x86_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED) 100 != __SIMPLELOCK_UNLOCKED) 101 x86_pause(); 102 __lockbarrier(); 103 } 104 105 static __inline int 106 __cpu_simple_lock_try(__cpu_simple_lock_t *lockp) 107 { 108 int r = (x86_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED) 109 == __SIMPLELOCK_UNLOCKED); 110 111 __lockbarrier(); 112 113 return (r); 114 } 115 116 static __inline void 117 __cpu_simple_unlock(__cpu_simple_lock_t *lockp) 118 { 119 120 __lockbarrier(); 121 *lockp = __SIMPLELOCK_UNLOCKED; 122 } 123 124 #endif /* !LOCKDEBUG */ 125 126 #endif /* _I386_LOCK_H_ */ 127