63 lines
2.4 KiB
C
63 lines
2.4 KiB
C
/*-
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* Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org>
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* All rights reserved.
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS__RWLOCK_H_
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#define _SYS__RWLOCK_H_
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#include <machine/param.h>
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/*
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* Reader/writer lock.
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*
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* All reader/writer lock implementations must always have a member
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* called rw_lock. Other locking primitive structures are not allowed to
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* use this name for their members.
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* If this rule needs to change, the bits in the reader/writer lock
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* implementation must be modified appropriately.
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*/
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struct rwlock {
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struct lock_object lock_object;
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volatile uintptr_t rw_lock;
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};
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/*
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* Members of struct rwlock_padalign must mirror members of struct rwlock.
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* rwlock_padalign rwlocks can use the rwlock(9) API transparently without
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* modification.
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* Pad-aligned rwlocks used within structures should generally be the
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* first member of the struct. Otherwise, the compiler can generate
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* additional padding for the struct to keep a correct alignment for
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* the rwlock.
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*/
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struct rwlock_padalign {
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struct lock_object lock_object;
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volatile uintptr_t rw_lock;
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} __aligned(CACHE_LINE_SIZE);
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#endif /* !_SYS__RWLOCK_H_ */
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