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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org>
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#ifndef _SYS__RWLOCK_H_
#define _SYS__RWLOCK_H_
#include <machine/param.h>
/*
* Reader/writer lock.
*
* All reader/writer lock implementations must always have a member
* called rw_lock. Other locking primitive structures are not allowed to
* use this name for their members.
* If this rule needs to change, the bits in the reader/writer lock
* implementation must be modified appropriately.
*/
struct rwlock {
struct lock_object lock_object;
volatile uintptr_t rw_lock;
};
/*
* Members of struct rwlock_padalign must mirror members of struct rwlock.
* rwlock_padalign rwlocks can use the rwlock(9) API transparently without
* modification.
* Pad-aligned rwlocks used within structures should generally be the
* first member of the struct. Otherwise, the compiler can generate
* additional padding for the struct to keep a correct alignment for
* the rwlock.
*/
struct rwlock_padalign {
struct lock_object lock_object;
volatile uintptr_t rw_lock;
} __aligned(CACHE_LINE_SIZE);
#endif /* !_SYS__RWLOCK_H_ */
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