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Diffstat (limited to 'sys/arch/i386/include/lock.h')
| -rw-r--r-- | sys/arch/i386/include/lock.h | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/sys/arch/i386/include/lock.h b/sys/arch/i386/include/lock.h new file mode 100644 index 00000000000..a647999a532 --- /dev/null +++ b/sys/arch/i386/include/lock.h @@ -0,0 +1,119 @@ +/* $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 <sys/cdefs.h> + * 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 <machine/atomic.h> + +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_ */ |