9c75ede409
lock optimized for almost exclusive reader access. (see also rmlock.9)
TODO:
Convert to per cpu variables linkerset as soon as it is available.
Optimize UP (single processor) case.
63 lines
2.2 KiB
C
63 lines
2.2 KiB
C
/*-
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* Copyright (c) 2007 Stephan Uphoff <ups@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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* 3. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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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__RMLOCK_H_
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#define _SYS__RMLOCK_H_
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/*
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* XXXUPS remove as soon as we have per cpu variable
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* linker sets and can define rm_queue in _rm_lock.h
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*/
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#include <sys/pcpu.h>
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/*
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* Mostly reader/occasional writer lock.
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*/
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LIST_HEAD(rmpriolist,rm_priotracker);
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struct rmlock {
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struct lock_object lock_object;
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volatile int rm_noreadtoken;
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LIST_HEAD(,rm_priotracker) rm_activeReaders;
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struct mtx rm_lock;
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};
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struct rm_priotracker {
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struct rm_queue rmp_cpuQueue; /* Must be first */
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struct rmlock *rmp_rmlock;
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struct thread *rmp_thread;
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int rmp_flags;
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LIST_ENTRY(rm_priotracker) rmp_qentry;
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};
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#endif /* !_SYS__RMLOCK_H_ */
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