95e5e988e0
original BSD code. The association between the vnode and the vm_object no longer includes reference counts. The major difference is that vm_object's are no longer freed gratuitiously from the vnode, and so once an object is created for the vnode, it will last as long as the vnode does. When a vnode object reference count is incremented, then the underlying vnode reference count is incremented also. The two "objects" are now more intimately related, and so the interactions are now much less complex. When vnodes are now normally placed onto the free queue with an object still attached. The rundown of the object happens at vnode rundown time, and happens with exactly the same filesystem semantics of the original VFS code. There is absolutely no need for vnode_pager_uncache and other travesties like that anymore. A side-effect of these changes is that SMP locking should be much simpler, the I/O copyin/copyout optimizations work, NFS should be more ponderable, and further work on layered filesystems should be less frustrating, because of the totally coherent management of the vnode objects and vnodes. Please be careful with your system while running this code, but I would greatly appreciate feedback as soon a reasonably possible.
195 lines
8.6 KiB
C
195 lines
8.6 KiB
C
/*
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* Copyright (c) 1995
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* The Regents of the University of California. All rights reserved.
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*
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* This code contains ideas from software contributed to Berkeley by
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* Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating
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* System project at Carnegie-Mellon University.
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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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* @(#)lock.h 8.12 (Berkeley) 5/19/95
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* $Id: lock.h,v 1.10 1997/09/21 04:24:02 dyson Exp $
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*/
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#ifndef _LOCK_H_
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#define _LOCK_H_
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#include <machine/lock.h>
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/*
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* The general lock structure. Provides for multiple shared locks,
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* upgrading from shared to exclusive, and sleeping until the lock
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* can be gained. The simple locks are defined in <machine/param.h>.
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*/
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struct lock {
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struct simplelock lk_interlock; /* lock on remaining fields */
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u_int lk_flags; /* see below */
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int lk_sharecount; /* # of accepted shared locks */
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int lk_waitcount; /* # of processes sleeping for lock */
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short lk_exclusivecount; /* # of recursive exclusive locks */
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short lk_prio; /* priority at which to sleep */
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char *lk_wmesg; /* resource sleeping (for tsleep) */
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int lk_timo; /* maximum sleep time (for tsleep) */
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pid_t lk_lockholder; /* pid of exclusive lock holder */
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};
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/*
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* Lock request types:
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* LK_SHARED - get one of many possible shared locks. If a process
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* holding an exclusive lock requests a shared lock, the exclusive
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* lock(s) will be downgraded to shared locks.
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* LK_EXCLUSIVE - stop further shared locks, when they are cleared,
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* grant a pending upgrade if it exists, then grant an exclusive
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* lock. Only one exclusive lock may exist at a time, except that
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* a process holding an exclusive lock may get additional exclusive
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* locks if it explicitly sets the LK_CANRECURSE flag in the lock
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* request, or if the LK_CANRECUSE flag was set when the lock was
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* initialized.
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* LK_UPGRADE - the process must hold a shared lock that it wants to
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* have upgraded to an exclusive lock. Other processes may get
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* exclusive access to the resource between the time that the upgrade
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* is requested and the time that it is granted.
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* LK_EXCLUPGRADE - the process must hold a shared lock that it wants to
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* have upgraded to an exclusive lock. If the request succeeds, no
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* other processes will have gotten exclusive access to the resource
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* between the time that the upgrade is requested and the time that
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* it is granted. However, if another process has already requested
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* an upgrade, the request will fail (see error returns below).
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* LK_DOWNGRADE - the process must hold an exclusive lock that it wants
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* to have downgraded to a shared lock. If the process holds multiple
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* (recursive) exclusive locks, they will all be downgraded to shared
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* locks.
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* LK_RELEASE - release one instance of a lock.
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* LK_DRAIN - wait for all activity on the lock to end, then mark it
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* decommissioned. This feature is used before freeing a lock that
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* is part of a piece of memory that is about to be freed.
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*
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* These are flags that are passed to the lockmgr routine.
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*/
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#define LK_TYPE_MASK 0x0000000f /* type of lock sought */
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#define LK_SHARED 0x00000001 /* shared lock */
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#define LK_EXCLUSIVE 0x00000002 /* exclusive lock */
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#define LK_UPGRADE 0x00000003 /* shared-to-exclusive upgrade */
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#define LK_EXCLUPGRADE 0x00000004 /* first shared-to-exclusive upgrade */
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#define LK_DOWNGRADE 0x00000005 /* exclusive-to-shared downgrade */
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#define LK_RELEASE 0x00000006 /* release any type of lock */
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#define LK_DRAIN 0x00000007 /* wait for all lock activity to end */
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/*
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* External lock flags.
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*
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* The first three flags may be set in lock_init to set their mode permanently,
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* or passed in as arguments to the lock manager. The LK_REENABLE flag may be
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* set only at the release of a lock obtained by drain.
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*/
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#define LK_EXTFLG_MASK 0x01000070 /* mask of external flags */
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#define LK_NOWAIT 0x00000010 /* do not sleep to await lock */
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#define LK_SLEEPFAIL 0x00000020 /* sleep, then return failure */
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#define LK_CANRECURSE 0x00000040 /* allow recursive exclusive lock */
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#define LK_REENABLE 0x00000080 /* lock is be reenabled after drain */
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#define LK_NOPAUSE 0x01000000 /* no spinloop */
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/*
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* Internal lock flags.
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*
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* These flags are used internally to the lock manager.
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*/
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#define LK_WANT_UPGRADE 0x00000100 /* waiting for share-to-excl upgrade */
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#define LK_WANT_EXCL 0x00000200 /* exclusive lock sought */
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#define LK_HAVE_EXCL 0x00000400 /* exclusive lock obtained */
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#define LK_WAITDRAIN 0x00000800 /* process waiting for lock to drain */
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#define LK_DRAINING 0x00004000 /* lock is being drained */
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#define LK_DRAINED 0x00008000 /* lock has been decommissioned */
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/*
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* Control flags
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*
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* Non-persistent external flags.
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*/
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#define LK_INTERLOCK 0x00010000 /* unlock passed simple lock after
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getting lk_interlock */
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#define LK_RETRY 0x00020000 /* vn_lock: retry until locked */
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#define LK_NOOBJ 0x00040000 /* vget: don't create object */
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/*
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* Internal state flags corresponding to lk_sharecount, and lk_waitcount
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*/
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#define LK_SHARE_NONZERO 0x00100000
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#define LK_WAIT_NONZERO 0x00200000
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/*
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* Lock return status.
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*
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* Successfully obtained locks return 0. Locks will always succeed
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* unless one of the following is true:
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* LK_FORCEUPGRADE is requested and some other process has already
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* requested a lock upgrade (returns EBUSY).
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* LK_WAIT is set and a sleep would be required (returns EBUSY).
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* LK_SLEEPFAIL is set and a sleep was done (returns ENOLCK).
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* PCATCH is set in lock priority and a signal arrives (returns
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* either EINTR or ERESTART if system calls is to be restarted).
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* Non-null lock timeout and timeout expires (returns EWOULDBLOCK).
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* A failed lock attempt always returns a non-zero error value. No lock
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* is held after an error return (in particular, a failed LK_UPGRADE
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* or LK_FORCEUPGRADE will have released its shared access lock).
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*/
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/*
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* Indicator that no process holds exclusive lock
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*/
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#define LK_KERNPROC ((pid_t) -2)
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#define LK_NOPROC ((pid_t) -1)
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void dumplockinfo(struct lock *lkp);
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struct proc;
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void lockinit __P((struct lock *, int prio, char *wmesg, int timo,
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int flags));
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int lockmgr __P((struct lock *, u_int flags,
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struct simplelock *, struct proc *p));
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void lockmgr_printinfo __P((struct lock *));
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int lockstatus __P((struct lock *));
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#ifdef SIMPLELOCK_DEBUG
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void _simple_unlock __P((struct simplelock *alp, const char *, int));
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#define simple_unlock(alp) _simple_unlock(alp, __FILE__, __LINE__)
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int _simple_lock_try __P((struct simplelock *alp, const char *, int));
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#define simple_lock_try(alp) _simple_lock_try(alp, __FILE__, __LINE__)
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void _simple_lock __P((struct simplelock *alp, const char *, int));
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#define simple_lock(alp) _simple_lock(alp, __FILE__, __LINE__)
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void simple_lock_init __P((struct simplelock *alp));
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#else /* !SIMPLELOCK_DEBUG */
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#if NCPUS == 1 /* no multiprocessor locking is necessary */
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#define simple_lock_init(alp)
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#define simple_lock(alp)
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#define simple_lock_try(alp) (1) /* always succeeds */
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#define simple_unlock(alp)
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#endif /* NCPUS == 1 */
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#endif /* !SIMPLELOCK_DEBUG */
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#endif /* !_LOCK_H_ */
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