c0011ad705
- document a data structure invariant in lockf.h - add KASSERT() to check the invariant. - be more consistent about dequeuing ourselves from the blocked list after a tsleep(). - Fix two places where the invariant is violated. - correct a few comments here and there - If we're still following a lock dependancy chain after maxlockdepth processes and haven't gotten back to the start, assume that we're in a cycle anyway and return EDEADLK. Fix is a superset of an existing fix in FreeBSD, but independantly derived. Fixes kern/3860.
99 lines
4.1 KiB
C
99 lines
4.1 KiB
C
/* $NetBSD: lockf.h,v 1.8 2000/06/12 14:33:04 sommerfeld Exp $ */
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/*
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Scooter Morris at Genentech Inc.
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its 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 REGENTS 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 REGENTS 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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* @(#)lockf.h 8.2 (Berkeley) 10/26/94
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*/
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#ifndef _SYS_LOCKF_H_
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#define _SYS_LOCKF_H_
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/*
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* The lockf structure is a kernel structure which contains the information
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* associated with a byte range lock. The lockf structures are linked into
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* the inode structure. Locks are sorted by the starting byte of the lock for
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* efficiency.
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*
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* lf_next is used for two purposes, depending on whether the lock is
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* being held, or is in conflict with an existing lock. If this lock
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* is held, it indicates the next lock on the same vnode.
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* For pending locks, if lock->lf_next is non-NULL, then lock->lf_block
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* must be queued on the lf_blkhd TAILQ of lock->lf_next.
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*/
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TAILQ_HEAD(locklist, lockf);
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struct lockf {
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short lf_flags; /* Lock semantics: F_POSIX, F_FLOCK, F_WAIT */
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short lf_type; /* Lock type: F_RDLCK, F_WRLCK */
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off_t lf_start; /* The byte # of the start of the lock */
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off_t lf_end; /* The byte # of the end of the lock (-1=EOF)*/
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caddr_t lf_id; /* The id of the resource holding the lock */
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struct lockf **lf_head; /* Back pointer to the head of lockf list */
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struct lockf *lf_next; /* Next lock on this vnode, or blocking lock */
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struct locklist lf_blkhd; /* List of requests blocked on this lock */
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TAILQ_ENTRY(lockf) lf_block;/* A request waiting for a lock */
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};
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/* Maximum length of sleep chains to traverse to try and detect deadlock. */
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#define MAXDEPTH 50
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__BEGIN_DECLS
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void lf_addblock __P((struct lockf *, struct lockf *));
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int lf_advlock __P((struct lockf **,
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off_t, caddr_t, int, struct flock *, int));
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int lf_clearlock __P((struct lockf *));
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int lf_findoverlap __P((struct lockf *,
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struct lockf *, int, struct lockf ***, struct lockf **));
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struct lockf *
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lf_getblock __P((struct lockf *));
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int lf_getlock __P((struct lockf *, struct flock *));
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int lf_setlock __P((struct lockf *));
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void lf_split __P((struct lockf *, struct lockf *));
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void lf_wakelock __P((struct lockf *));
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__END_DECLS
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#ifdef LOCKF_DEBUG
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extern int lockf_debug;
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__BEGIN_DECLS
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void lf_print __P((char *, struct lockf *));
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void lf_printlist __P((char *, struct lockf *));
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__END_DECLS
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#endif /* LOCKF_DEBUG */
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#endif /* !_SYS_LOCKF_H_ */
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