83 lines
3.0 KiB
C
83 lines
3.0 KiB
C
/*-
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* Copyright (c) 2009 Konstantin Belousov <kib@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 unmodified, this list of conditions, and the following
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* 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 ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS_RANGELOCK_H
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#define _SYS_RANGELOCK_H
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#include <sys/queue.h>
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#define RL_LOCK_READ 0x0001
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#define RL_LOCK_WRITE 0x0002
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#define RL_LOCK_TYPE_MASK 0x0003
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#define RL_LOCK_GRANTED 0x0004
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struct rl_q_entry;
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/*
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* The structure representing the range lock. Caller may request
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* read or write access to the range of bytes. Access is granted if
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* all existing lock owners are compatible with the request. Two lock
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* owners are compatible if their ranges do not overlap, or both
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* owners are for read.
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*
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* Access to the structure itself is synchronized with the externally
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* supplied mutex.
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*
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* rl_waiters is the queue containing in order (a) granted write lock
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* requests, (b) granted read lock requests, and (c) in order of arrival,
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* lock requests which cannot be granted yet.
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*
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* rl_currdep is the first lock request that cannot be granted now due
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* to the preceding requests conflicting with it (i.e., it points to
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* position (c) in the list above).
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*/
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struct rangelock {
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TAILQ_HEAD(, rl_q_entry) rl_waiters;
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struct rl_q_entry *rl_currdep;
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};
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#ifdef _KERNEL
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struct mtx;
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void rangelock_init(struct rangelock *lock);
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void rangelock_destroy(struct rangelock *lock);
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void rangelock_unlock(struct rangelock *lock, void *cookie,
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struct mtx *ilk);
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void *rangelock_unlock_range(struct rangelock *lock, void *cookie,
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off_t start, off_t end, struct mtx *ilk);
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void *rangelock_rlock(struct rangelock *lock, off_t start, off_t end,
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struct mtx *ilk);
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void *rangelock_wlock(struct rangelock *lock, off_t start, off_t end,
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struct mtx *ilk);
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void rlqentry_free(struct rl_q_entry *rlqe);
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#endif /* _KERNEL */
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#endif /* _SYS_RANGELOCK_H */
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