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spinlock.h
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/
spinlock.h
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/*
* Copyright (c) 2005 Jeffrey M. Hsu. All rights reserved.
*
* This code is derived from software contributed to The DragonFly Project
* by Jeffrey M. Hsu.
*
* 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. Neither the name of The DragonFly Project 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDERS 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.
*
* $DragonFly: src/sys/sys/spinlock.h,v 1.5 2006/05/26 02:26:26 dillon Exp $
*/
#ifndef _SYS_SPINLOCK_H_
#define _SYS_SPINLOCK_H_
/*
* Note that the spinlock structure is retained whether we are SMP or not,
* so structures using embedded spinlocks do not change size for SMP vs UP
* builds.
*/
struct spinlock {
volatile int lock; /* 0 = unlocked, 1 = locked */
};
#define SPINLOCK_EXCLUSIVE 0x80000000
#define SPINLOCK_INITIALIZER(head) { 0 }
#endif