107 lines
3.5 KiB
C
107 lines
3.5 KiB
C
/* $NetBSD: lock.h,v 1.4 1999/07/27 23:45:14 thorpej Exp $ */
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/*-
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* Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Paul Kranenburg.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _MACHINE_LOCK_H
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#define _MACHINE_LOCK_H
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/*
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* Machine dependent spin lock operations.
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*/
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#if defined(_KERNEL)
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#include <sparc64/sparc64/asm.h>
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/*
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* The value for SIMPLELOCK_LOCKED is what ldstub() naturally stores
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* `lock_data' given its address (and the fact that SPARC is big-endian).
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*/
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#undef SIMPLELOCK_LOCKED
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#define SIMPLELOCK_LOCKED 0xff000000
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static void cpu_simple_lock_init __P((__volatile struct simplelock *));
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static void cpu_simple_lock __P((__volatile struct simplelock *));
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static int cpu_simple_lock_try __P((__volatile struct simplelock *));
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static void cpu_simple_unlock __P((__volatile struct simplelock *));
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static __inline__ void
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cpu_simple_lock_init (alp)
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__volatile struct simplelock *alp;
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{
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alp->lock_data = SIMPLELOCK_UNLOCKED;
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}
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static __inline__ void
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cpu_simple_lock (alp)
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__volatile struct simplelock *alp;
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{
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/*
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* If someone else holds the lock use simple
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* reads until it is released, then retry the
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* atomic operation. This reduces memory bus contention
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* becaused the cache-coherency logic does not have to
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* broadcast invalidates on the lock while we spin on it.
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*/
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while (ldstub(&alp->lock_data) != SIMPLELOCK_UNLOCKED) {
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while (alp->lock_data != SIMPLELOCK_UNLOCKED)
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/*void*/;
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}
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}
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static __inline__ int
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cpu_simple_lock_try (alp)
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__volatile struct simplelock *alp;
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{
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return (ldstub(&alp->lock_data) == SIMPLELOCK_UNLOCKED);
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}
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static __inline__ void
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cpu_simple_unlock (alp)
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__volatile struct simplelock *alp;
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{
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alp->lock_data = SIMPLELOCK_UNLOCKED;
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}
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#endif /* _KERNEL */
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#endif /* _MACHINE_LOCK_H */
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