/* $OpenBSD: lock.h,v 1.2 2004/06/13 21:49:16 niklas Exp $ */ /* $NetBSD: lock.h,v 1.1.2.2 2000/05/03 14:40:55 sommerfeld Exp $ */ /*- * Copyright (c) 2000 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Machine-dependent spin lock operations. */ #ifndef _I386_LOCK_H_ #define _I386_LOCK_H_ typedef __volatile int __cpu_simple_lock_t; #define __SIMPLELOCK_LOCKED 1 #define __SIMPLELOCK_UNLOCKED 0 /* * compiler barrier: prevent reordering of instructions. * XXX something similar will move to * or thereabouts. * This prevents the compiler from reordering code around * this "instruction", acting as a sequence point for code generation. */ #define __lockbarrier() __asm __volatile("": : :"memory") #ifdef LOCKDEBUG extern void __cpu_simple_lock_init(__cpu_simple_lock_t *); extern void __cpu_simple_lock(__cpu_simple_lock_t *); extern int __cpu_simple_lock_try(__cpu_simple_lock_t *); extern void __cpu_simple_unlock(__cpu_simple_lock_t *); #else #include static __inline void __cpu_simple_lock_init(__cpu_simple_lock_t *) __attribute__((__unused__)); static __inline void __cpu_simple_lock(__cpu_simple_lock_t *) __attribute__((__unused__)); static __inline int __cpu_simple_lock_try(__cpu_simple_lock_t *) __attribute__((__unused__)); static __inline void __cpu_simple_unlock(__cpu_simple_lock_t *) __attribute__((__unused__)); static __inline void __cpu_simple_lock_init(__cpu_simple_lock_t *lockp) { *lockp = __SIMPLELOCK_UNLOCKED; __lockbarrier(); } static __inline void __cpu_simple_lock(__cpu_simple_lock_t *lockp) { while (i386_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED) == __SIMPLELOCK_LOCKED) { continue; /* spin */ } __lockbarrier(); } static __inline int __cpu_simple_lock_try(__cpu_simple_lock_t *lockp) { int r = (i386_atomic_testset_i(lockp, __SIMPLELOCK_LOCKED) == __SIMPLELOCK_UNLOCKED); __lockbarrier(); return (r); } static __inline void __cpu_simple_unlock(__cpu_simple_lock_t *lockp) { __lockbarrier(); *lockp = __SIMPLELOCK_UNLOCKED; } #endif /* !LOCKDEBUG */ #endif /* _I386_LOCK_H_ */