e964d558a7
- add a new global variable, doing_shutdown, which is nonzero if vfs_shutdown() or panic() have been called. - in panic, set RB_NOSYNC if doing_shutdown is already set on entry so we don't reenter vfs_shutdown if we panic'ed there. - in vfs_shutdown, don't use proc0's process for sys_sync unless curproc is NULL. - in lockmgr, attribute successful locks to proc0 if doing_shutdown && curproc==NULL, and panic if we can't get the lock right away; avoids the spurious lockmgr DIAGNOSTIC panic from the ddb reboot command. - in subr_pool, deal with curproc==NULL in the doing_shutdown case. - in mfs_strategy, bitbucket writes if doing_shutdown, so we don't wedge waiting for the mfs process. - in ltsleep, treat ((curproc == NULL) && doing_shutdown) like the panicstr case. Appears to fix: kern/9239, kern/10187, kern/9367. May also fix kern/10122.
964 lines
26 KiB
C
964 lines
26 KiB
C
/* $NetBSD: kern_lock.c,v 1.32 2000/06/10 18:44:43 sommerfeld Exp $ */
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/*-
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* Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
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* NASA Ames Research Center.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Ross Harvey.
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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
|
|
* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
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* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
|
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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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
|
|
* 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
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
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* 4. Neither the name of the University nor the names of its contributors
|
|
* 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
|
|
* 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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* @(#)kern_lock.c 8.18 (Berkeley) 5/21/95
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*/
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#include "opt_multiprocessor.h"
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#include "opt_lockdebug.h"
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#include "opt_ddb.h"
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#include <sys/param.h>
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#include <sys/proc.h>
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#include <sys/lock.h>
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#include <sys/systm.h>
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#include <machine/cpu.h>
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#if defined(__HAVE_ATOMIC_OPERATIONS)
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#include <machine/atomic.h>
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#endif
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|
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#if defined(LOCKDEBUG)
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#include <sys/syslog.h>
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/*
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* note that stdarg.h and the ansi style va_start macro is used for both
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* ansi and traditional c compiles.
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* XXX: this requires that stdarg.h define: va_alist and va_dcl
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*/
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#include <machine/stdarg.h>
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void lock_printf __P((const char *fmt, ...));
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int lock_debug_syslog = 0; /* defaults to printf, but can be patched */
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#endif
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|
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/*
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* Locking primitives implementation.
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* Locks provide shared/exclusive sychronization.
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*/
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#if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */
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#if defined(MULTIPROCESSOR) /* { */
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#if defined(__HAVE_ATOMIC_OPERATIONS) /* { */
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#define COUNT_CPU(cpu_id, x) \
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atomic_add_ulong(&curcpu()->ci_spin_locks, (x))
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#else
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#define COUNT_CPU(cpu_id, x) /* not safe */
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#endif /* __HAVE_ATOMIC_OPERATIONS */ /* } */
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#else
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u_long spin_locks;
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#define COUNT_CPU(cpu_id, x) spin_locks += (x)
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#endif /* MULTIPROCESSOR */ /* } */
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#define COUNT(lkp, p, cpu_id, x) \
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do { \
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if ((lkp)->lk_flags & LK_SPIN) \
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COUNT_CPU((cpu_id), (x)); \
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else \
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(p)->p_locks += (x); \
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} while (/*CONSTCOND*/0)
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#else
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#define COUNT(lkp, p, cpu_id, x)
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#endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */
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/*
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* Acquire a resource.
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*/
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#define ACQUIRE(lkp, error, extflags, drain, wanted) \
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if ((extflags) & LK_SPIN) { \
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int interlocked; \
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\
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if ((drain) == 0) \
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(lkp)->lk_waitcount++; \
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for (interlocked = 1;;) { \
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if (wanted) { \
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if (interlocked) { \
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simple_unlock(&(lkp)->lk_interlock); \
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interlocked = 0; \
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} \
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} else if (interlocked) { \
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break; \
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} else { \
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simple_lock(&(lkp)->lk_interlock); \
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interlocked = 1; \
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} \
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} \
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if ((drain) == 0) \
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(lkp)->lk_waitcount--; \
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KASSERT((wanted) == 0); \
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error = 0; /* sanity */ \
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} else { \
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for (error = 0; wanted; ) { \
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if ((drain)) \
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(lkp)->lk_flags |= LK_WAITDRAIN; \
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else \
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(lkp)->lk_waitcount++; \
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/* XXX Cast away volatile. */ \
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error = ltsleep((drain) ? &(lkp)->lk_flags : \
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(void *)(lkp), (lkp)->lk_prio, \
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(lkp)->lk_wmesg, (lkp)->lk_timo, \
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&(lkp)->lk_interlock); \
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if ((drain) == 0) \
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(lkp)->lk_waitcount--; \
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if (error) \
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break; \
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if ((extflags) & LK_SLEEPFAIL) { \
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error = ENOLCK; \
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break; \
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} \
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} \
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}
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#define SETHOLDER(lkp, pid, cpu_id) \
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do { \
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if ((lkp)->lk_flags & LK_SPIN) \
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(lkp)->lk_cpu = cpu_id; \
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else \
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(lkp)->lk_lockholder = pid; \
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} while (/*CONSTCOND*/0)
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#define WEHOLDIT(lkp, pid, cpu_id) \
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(((lkp)->lk_flags & LK_SPIN) != 0 ? \
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((lkp)->lk_cpu == (cpu_id)) : ((lkp)->lk_lockholder == (pid)))
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#define WAKEUP_WAITER(lkp) \
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do { \
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if (((lkp)->lk_flags & LK_SPIN) == 0 && (lkp)->lk_waitcount) { \
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/* XXX Cast away volatile. */ \
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wakeup_one((void *)(lkp)); \
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} \
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} while (/*CONSTCOND*/0)
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#if defined(LOCKDEBUG) /* { */
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#if defined(MULTIPROCESSOR) /* { */
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struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER;
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#define SPINLOCK_LIST_LOCK() \
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__cpu_simple_lock(&spinlock_list_slock.lock_data)
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#define SPINLOCK_LIST_UNLOCK() \
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__cpu_simple_unlock(&spinlock_list_slock.lock_data)
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#else
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#define SPINLOCK_LIST_LOCK() /* nothing */
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#define SPINLOCK_LIST_UNLOCK() /* nothing */
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#endif /* MULTIPROCESSOR */ /* } */
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TAILQ_HEAD(, lock) spinlock_list =
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TAILQ_HEAD_INITIALIZER(spinlock_list);
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#define HAVEIT(lkp) \
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do { \
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if ((lkp)->lk_flags & LK_SPIN) { \
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int s = splhigh(); \
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SPINLOCK_LIST_LOCK(); \
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/* XXX Cast away volatile. */ \
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TAILQ_INSERT_TAIL(&spinlock_list, (struct lock *)(lkp), \
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lk_list); \
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SPINLOCK_LIST_UNLOCK(); \
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splx(s); \
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} \
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} while (/*CONSTCOND*/0)
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|
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#define DONTHAVEIT(lkp) \
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do { \
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if ((lkp)->lk_flags & LK_SPIN) { \
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int s = splhigh(); \
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SPINLOCK_LIST_LOCK(); \
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/* XXX Cast away volatile. */ \
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TAILQ_REMOVE(&spinlock_list, (struct lock *)(lkp), \
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lk_list); \
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SPINLOCK_LIST_UNLOCK(); \
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splx(s); \
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} \
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} while (/*CONSTCOND*/0)
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#else
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#define HAVEIT(lkp) /* nothing */
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#define DONTHAVEIT(lkp) /* nothing */
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#endif /* LOCKDEBUG */ /* } */
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|
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#if defined(LOCKDEBUG)
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/*
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* Lock debug printing routine; can be configured to print to console
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* or log to syslog.
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*/
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void
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#ifdef __STDC__
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lock_printf(const char *fmt, ...)
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#else
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lock_printf(fmt, va_alist)
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char *fmt;
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va_dcl
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#endif
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{
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va_list ap;
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va_start(ap, fmt);
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if (lock_debug_syslog)
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vlog(LOG_DEBUG, fmt, ap);
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else
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vprintf(fmt, ap);
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va_end(ap);
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}
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#endif /* LOCKDEBUG */
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|
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/*
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* Initialize a lock; required before use.
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*/
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void
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lockinit(lkp, prio, wmesg, timo, flags)
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struct lock *lkp;
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int prio;
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const char *wmesg;
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int timo;
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int flags;
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{
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memset(lkp, 0, sizeof(struct lock));
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simple_lock_init(&lkp->lk_interlock);
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lkp->lk_flags = flags & LK_EXTFLG_MASK;
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if (flags & LK_SPIN)
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lkp->lk_cpu = LK_NOCPU;
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else {
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lkp->lk_lockholder = LK_NOPROC;
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lkp->lk_prio = prio;
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lkp->lk_timo = timo;
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}
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lkp->lk_wmesg = wmesg; /* just a name for spin locks */
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}
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|
|
/*
|
|
* Determine the status of a lock.
|
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*/
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int
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lockstatus(lkp)
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struct lock *lkp;
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{
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int lock_type = 0;
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|
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simple_lock(&lkp->lk_interlock);
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if (lkp->lk_exclusivecount != 0)
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lock_type = LK_EXCLUSIVE;
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else if (lkp->lk_sharecount != 0)
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lock_type = LK_SHARED;
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simple_unlock(&lkp->lk_interlock);
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return (lock_type);
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}
|
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|
|
/*
|
|
* XXX XXX kludge around another kludge..
|
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*
|
|
* vfs_shutdown() may be called from interrupt context, either as a result
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* of a panic, or from the debugger. It proceeds to call
|
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* sys_sync(&proc0, ...), pretending its running on behalf of proc0
|
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*
|
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* We would like to make an attempt to sync the filesystems in this case, so
|
|
* if this happens, we treat attempts to acquire locks specially.
|
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* All locks are acquired on behalf of proc0.
|
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*
|
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* If we've already paniced, we don't block waiting for locks, but
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* just barge right ahead since we're already going down in flames.
|
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*/
|
|
|
|
/*
|
|
* Set, change, or release a lock.
|
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*
|
|
* Shared requests increment the shared count. Exclusive requests set the
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* LK_WANT_EXCL flag (preventing further shared locks), and wait for already
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* accepted shared locks and shared-to-exclusive upgrades to go away.
|
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*/
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int
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lockmgr(lkp, flags, interlkp)
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__volatile struct lock *lkp;
|
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u_int flags;
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struct simplelock *interlkp;
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{
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int error;
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pid_t pid;
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int extflags;
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cpuid_t cpu_id;
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struct proc *p = curproc;
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|
int lock_shutdown_noblock = 0;
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error = 0;
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|
|
simple_lock(&lkp->lk_interlock);
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if (flags & LK_INTERLOCK)
|
|
simple_unlock(interlkp);
|
|
extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK;
|
|
|
|
#ifdef DIAGNOSTIC /* { */
|
|
/*
|
|
* Don't allow spins on sleep locks and don't allow sleeps
|
|
* on spin locks.
|
|
*/
|
|
if ((flags ^ lkp->lk_flags) & LK_SPIN)
|
|
panic("lockmgr: sleep/spin mismatch\n");
|
|
#endif /* } */
|
|
|
|
if (extflags & LK_SPIN)
|
|
pid = LK_KERNPROC;
|
|
else {
|
|
if (p == NULL) {
|
|
if (!doing_shutdown) {
|
|
#ifdef DIAGNOSTIC
|
|
panic("lockmgr: no context");
|
|
#endif
|
|
} else {
|
|
p = &proc0;
|
|
if (panicstr && (!(flags & LK_NOWAIT))) {
|
|
flags |= LK_NOWAIT;
|
|
lock_shutdown_noblock = 1;
|
|
}
|
|
}
|
|
}
|
|
pid = p->p_pid;
|
|
}
|
|
cpu_id = cpu_number();
|
|
|
|
/*
|
|
* Once a lock has drained, the LK_DRAINING flag is set and an
|
|
* exclusive lock is returned. The only valid operation thereafter
|
|
* is a single release of that exclusive lock. This final release
|
|
* clears the LK_DRAINING flag and sets the LK_DRAINED flag. Any
|
|
* further requests of any sort will result in a panic. The bits
|
|
* selected for these two flags are chosen so that they will be set
|
|
* in memory that is freed (freed memory is filled with 0xdeadbeef).
|
|
* The final release is permitted to give a new lease on life to
|
|
* the lock by specifying LK_REENABLE.
|
|
*/
|
|
if (lkp->lk_flags & (LK_DRAINING|LK_DRAINED)) {
|
|
#ifdef DIAGNOSTIC /* { */
|
|
if (lkp->lk_flags & LK_DRAINED)
|
|
panic("lockmgr: using decommissioned lock");
|
|
if ((flags & LK_TYPE_MASK) != LK_RELEASE ||
|
|
WEHOLDIT(lkp, pid, cpu_id) == 0)
|
|
panic("lockmgr: non-release on draining lock: %d\n",
|
|
flags & LK_TYPE_MASK);
|
|
#endif /* DIAGNOSTIC */ /* } */
|
|
lkp->lk_flags &= ~LK_DRAINING;
|
|
if ((flags & LK_REENABLE) == 0)
|
|
lkp->lk_flags |= LK_DRAINED;
|
|
}
|
|
|
|
switch (flags & LK_TYPE_MASK) {
|
|
|
|
case LK_SHARED:
|
|
if (WEHOLDIT(lkp, pid, cpu_id) == 0) {
|
|
/*
|
|
* If just polling, check to see if we will block.
|
|
*/
|
|
if ((extflags & LK_NOWAIT) && (lkp->lk_flags &
|
|
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE))) {
|
|
error = EBUSY;
|
|
break;
|
|
}
|
|
/*
|
|
* Wait for exclusive locks and upgrades to clear.
|
|
*/
|
|
ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags &
|
|
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE));
|
|
if (error)
|
|
break;
|
|
lkp->lk_sharecount++;
|
|
COUNT(lkp, p, cpu_id, 1);
|
|
break;
|
|
}
|
|
/*
|
|
* We hold an exclusive lock, so downgrade it to shared.
|
|
* An alternative would be to fail with EDEADLK.
|
|
*/
|
|
lkp->lk_sharecount++;
|
|
COUNT(lkp, p, cpu_id, 1);
|
|
/* fall into downgrade */
|
|
|
|
case LK_DOWNGRADE:
|
|
if (WEHOLDIT(lkp, pid, cpu_id) == 0 ||
|
|
lkp->lk_exclusivecount == 0)
|
|
panic("lockmgr: not holding exclusive lock");
|
|
lkp->lk_sharecount += lkp->lk_exclusivecount;
|
|
lkp->lk_exclusivecount = 0;
|
|
lkp->lk_recurselevel = 0;
|
|
lkp->lk_flags &= ~LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, LK_NOPROC, LK_NOCPU);
|
|
DONTHAVEIT(lkp);
|
|
WAKEUP_WAITER(lkp);
|
|
break;
|
|
|
|
case LK_EXCLUPGRADE:
|
|
/*
|
|
* If another process is ahead of us to get an upgrade,
|
|
* then we want to fail rather than have an intervening
|
|
* exclusive access.
|
|
*/
|
|
if (lkp->lk_flags & LK_WANT_UPGRADE) {
|
|
lkp->lk_sharecount--;
|
|
COUNT(lkp, p, cpu_id, -1);
|
|
error = EBUSY;
|
|
break;
|
|
}
|
|
/* fall into normal upgrade */
|
|
|
|
case LK_UPGRADE:
|
|
/*
|
|
* Upgrade a shared lock to an exclusive one. If another
|
|
* shared lock has already requested an upgrade to an
|
|
* exclusive lock, our shared lock is released and an
|
|
* exclusive lock is requested (which will be granted
|
|
* after the upgrade). If we return an error, the file
|
|
* will always be unlocked.
|
|
*/
|
|
if (WEHOLDIT(lkp, pid, cpu_id) || lkp->lk_sharecount <= 0)
|
|
panic("lockmgr: upgrade exclusive lock");
|
|
lkp->lk_sharecount--;
|
|
COUNT(lkp, p, cpu_id, -1);
|
|
/*
|
|
* If we are just polling, check to see if we will block.
|
|
*/
|
|
if ((extflags & LK_NOWAIT) &&
|
|
((lkp->lk_flags & LK_WANT_UPGRADE) ||
|
|
lkp->lk_sharecount > 1)) {
|
|
error = EBUSY;
|
|
break;
|
|
}
|
|
if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) {
|
|
/*
|
|
* We are first shared lock to request an upgrade, so
|
|
* request upgrade and wait for the shared count to
|
|
* drop to zero, then take exclusive lock.
|
|
*/
|
|
lkp->lk_flags |= LK_WANT_UPGRADE;
|
|
ACQUIRE(lkp, error, extflags, 0, lkp->lk_sharecount);
|
|
lkp->lk_flags &= ~LK_WANT_UPGRADE;
|
|
if (error)
|
|
break;
|
|
lkp->lk_flags |= LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, pid, cpu_id);
|
|
HAVEIT(lkp);
|
|
if (lkp->lk_exclusivecount != 0)
|
|
panic("lockmgr: non-zero exclusive count");
|
|
lkp->lk_exclusivecount = 1;
|
|
if (extflags & LK_SETRECURSE)
|
|
lkp->lk_recurselevel = 1;
|
|
COUNT(lkp, p, cpu_id, 1);
|
|
break;
|
|
}
|
|
/*
|
|
* Someone else has requested upgrade. Release our shared
|
|
* lock, awaken upgrade requestor if we are the last shared
|
|
* lock, then request an exclusive lock.
|
|
*/
|
|
if (lkp->lk_sharecount == 0)
|
|
WAKEUP_WAITER(lkp);
|
|
/* fall into exclusive request */
|
|
|
|
case LK_EXCLUSIVE:
|
|
if (WEHOLDIT(lkp, pid, cpu_id)) {
|
|
/*
|
|
* Recursive lock.
|
|
*/
|
|
if ((extflags & LK_CANRECURSE) == 0 &&
|
|
lkp->lk_recurselevel == 0) {
|
|
if (extflags & LK_RECURSEFAIL) {
|
|
error = EDEADLK;
|
|
break;
|
|
} else
|
|
panic("lockmgr: locking against myself");
|
|
}
|
|
lkp->lk_exclusivecount++;
|
|
if (extflags & LK_SETRECURSE &&
|
|
lkp->lk_recurselevel == 0)
|
|
lkp->lk_recurselevel = lkp->lk_exclusivecount;
|
|
COUNT(lkp, p, cpu_id, 1);
|
|
break;
|
|
}
|
|
/*
|
|
* If we are just polling, check to see if we will sleep.
|
|
*/
|
|
if ((extflags & LK_NOWAIT) && ((lkp->lk_flags &
|
|
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
|
|
lkp->lk_sharecount != 0)) {
|
|
error = EBUSY;
|
|
break;
|
|
}
|
|
/*
|
|
* Try to acquire the want_exclusive flag.
|
|
*/
|
|
ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags &
|
|
(LK_HAVE_EXCL | LK_WANT_EXCL));
|
|
if (error)
|
|
break;
|
|
lkp->lk_flags |= LK_WANT_EXCL;
|
|
/*
|
|
* Wait for shared locks and upgrades to finish.
|
|
*/
|
|
ACQUIRE(lkp, error, extflags, 0, lkp->lk_sharecount != 0 ||
|
|
(lkp->lk_flags & LK_WANT_UPGRADE));
|
|
lkp->lk_flags &= ~LK_WANT_EXCL;
|
|
if (error)
|
|
break;
|
|
lkp->lk_flags |= LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, pid, cpu_id);
|
|
HAVEIT(lkp);
|
|
if (lkp->lk_exclusivecount != 0)
|
|
panic("lockmgr: non-zero exclusive count");
|
|
lkp->lk_exclusivecount = 1;
|
|
if (extflags & LK_SETRECURSE)
|
|
lkp->lk_recurselevel = 1;
|
|
COUNT(lkp, p, cpu_id, 1);
|
|
break;
|
|
|
|
case LK_RELEASE:
|
|
if (lkp->lk_exclusivecount != 0) {
|
|
if (WEHOLDIT(lkp, pid, cpu_id) == 0) {
|
|
if (lkp->lk_flags & LK_SPIN) {
|
|
panic("lockmgr: processor %lu, not "
|
|
"exclusive lock holder %lu "
|
|
"unlocking", cpu_id, lkp->lk_cpu);
|
|
} else {
|
|
panic("lockmgr: pid %d, not "
|
|
"exclusive lock holder %d "
|
|
"unlocking", pid,
|
|
lkp->lk_lockholder);
|
|
}
|
|
}
|
|
if (lkp->lk_exclusivecount == lkp->lk_recurselevel)
|
|
lkp->lk_recurselevel = 0;
|
|
lkp->lk_exclusivecount--;
|
|
COUNT(lkp, p, cpu_id, -1);
|
|
if (lkp->lk_exclusivecount == 0) {
|
|
lkp->lk_flags &= ~LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, LK_NOPROC, LK_NOCPU);
|
|
DONTHAVEIT(lkp);
|
|
}
|
|
} else if (lkp->lk_sharecount != 0) {
|
|
lkp->lk_sharecount--;
|
|
COUNT(lkp, p, cpu_id, -1);
|
|
}
|
|
WAKEUP_WAITER(lkp);
|
|
break;
|
|
|
|
case LK_DRAIN:
|
|
/*
|
|
* Check that we do not already hold the lock, as it can
|
|
* never drain if we do. Unfortunately, we have no way to
|
|
* check for holding a shared lock, but at least we can
|
|
* check for an exclusive one.
|
|
*/
|
|
if (WEHOLDIT(lkp, pid, cpu_id))
|
|
panic("lockmgr: draining against myself");
|
|
/*
|
|
* If we are just polling, check to see if we will sleep.
|
|
*/
|
|
if ((extflags & LK_NOWAIT) && ((lkp->lk_flags &
|
|
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
|
|
lkp->lk_sharecount != 0 || lkp->lk_waitcount != 0)) {
|
|
error = EBUSY;
|
|
break;
|
|
}
|
|
ACQUIRE(lkp, error, extflags, 1,
|
|
((lkp->lk_flags &
|
|
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
|
|
lkp->lk_sharecount != 0 ||
|
|
lkp->lk_waitcount != 0));
|
|
if (error)
|
|
break;
|
|
lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, pid, cpu_id);
|
|
HAVEIT(lkp);
|
|
lkp->lk_exclusivecount = 1;
|
|
/* XXX unlikely that we'd want this */
|
|
if (extflags & LK_SETRECURSE)
|
|
lkp->lk_recurselevel = 1;
|
|
COUNT(lkp, p, cpu_id, 1);
|
|
break;
|
|
|
|
default:
|
|
simple_unlock(&lkp->lk_interlock);
|
|
panic("lockmgr: unknown locktype request %d",
|
|
flags & LK_TYPE_MASK);
|
|
/* NOTREACHED */
|
|
}
|
|
if ((lkp->lk_flags & (LK_WAITDRAIN|LK_SPIN)) == LK_WAITDRAIN &&
|
|
((lkp->lk_flags &
|
|
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) == 0 &&
|
|
lkp->lk_sharecount == 0 && lkp->lk_waitcount == 0)) {
|
|
lkp->lk_flags &= ~LK_WAITDRAIN;
|
|
wakeup_one((void *)&lkp->lk_flags);
|
|
}
|
|
/*
|
|
* Note that this panic will be a recursive panic, since
|
|
* we only set lock_shutdown_noblock above if panicstr != NULL.
|
|
*/
|
|
if (error && lock_shutdown_noblock)
|
|
panic("lockmgr: deadlock (see previous panic)");
|
|
|
|
simple_unlock(&lkp->lk_interlock);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Print out information about state of a lock. Used by VOP_PRINT
|
|
* routines to display ststus about contained locks.
|
|
*/
|
|
void
|
|
lockmgr_printinfo(lkp)
|
|
__volatile struct lock *lkp;
|
|
{
|
|
|
|
if (lkp->lk_sharecount)
|
|
printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg,
|
|
lkp->lk_sharecount);
|
|
else if (lkp->lk_flags & LK_HAVE_EXCL) {
|
|
printf(" lock type %s: EXCL (count %d) by ",
|
|
lkp->lk_wmesg, lkp->lk_exclusivecount);
|
|
if (lkp->lk_flags & LK_SPIN)
|
|
printf("processor %lu", lkp->lk_cpu);
|
|
else
|
|
printf("pid %d", lkp->lk_lockholder);
|
|
} else
|
|
printf(" not locked");
|
|
if ((lkp->lk_flags & LK_SPIN) == 0 && lkp->lk_waitcount > 0)
|
|
printf(" with %d pending", lkp->lk_waitcount);
|
|
}
|
|
|
|
#if defined(LOCKDEBUG) /* { */
|
|
TAILQ_HEAD(, simplelock) simplelock_list =
|
|
TAILQ_HEAD_INITIALIZER(simplelock_list);
|
|
|
|
#if defined(MULTIPROCESSOR) /* { */
|
|
struct simplelock simplelock_list_slock = SIMPLELOCK_INITIALIZER;
|
|
|
|
#define SLOCK_LIST_LOCK() \
|
|
__cpu_simple_lock(&simplelock_list_slock.lock_data)
|
|
|
|
#define SLOCK_LIST_UNLOCK() \
|
|
__cpu_simple_unlock(&simplelock_list_slock.lock_data)
|
|
|
|
#if defined(__HAVE_ATOMIC_OPERATIONS) /* { */
|
|
#define SLOCK_COUNT(x) \
|
|
atomic_add_ulong(&curcpu()->ci_simple_locks, (x))
|
|
#else
|
|
#define SLOCK_COUNT(x) /* not safe */
|
|
#endif /* __HAVE_ATOMIC_OPERATIONS */ /* } */
|
|
#else
|
|
u_long simple_locks;
|
|
|
|
#define SLOCK_LIST_LOCK() /* nothing */
|
|
|
|
#define SLOCK_LIST_UNLOCK() /* nothing */
|
|
|
|
#define SLOCK_COUNT(x) simple_locks += (x)
|
|
#endif /* MULTIPROCESSOR */ /* } */
|
|
|
|
#ifdef DDB /* { */
|
|
int simple_lock_debugger = 0;
|
|
#define SLOCK_DEBUGGER() if (simple_lock_debugger) Debugger()
|
|
#else
|
|
#define SLOCK_DEBUGGER() /* nothing */
|
|
#endif /* } */
|
|
|
|
#ifdef MULTIPROCESSOR
|
|
#define SLOCK_MP() lock_printf("on cpu %d\n", cpu_number())
|
|
#else
|
|
#define SLOCK_MP() /* nothing */
|
|
#endif
|
|
|
|
#define SLOCK_WHERE(str, alp, id, l) \
|
|
do { \
|
|
lock_printf(str); \
|
|
lock_printf("lock: %p, currently at: %s:%d\n", (alp), (id), (l)); \
|
|
SLOCK_MP(); \
|
|
if ((alp)->lock_file != NULL) \
|
|
lock_printf("last locked: %s:%d\n", (alp)->lock_file, \
|
|
(alp)->lock_line); \
|
|
if ((alp)->unlock_file != NULL) \
|
|
lock_printf("last unlocked: %s:%d\n", (alp)->unlock_file, \
|
|
(alp)->unlock_line); \
|
|
SLOCK_DEBUGGER(); \
|
|
} while (/*CONSTCOND*/0)
|
|
|
|
/*
|
|
* Simple lock functions so that the debugger can see from whence
|
|
* they are being called.
|
|
*/
|
|
void
|
|
simple_lock_init(alp)
|
|
struct simplelock *alp;
|
|
{
|
|
|
|
#if defined(MULTIPROCESSOR) /* { */
|
|
__cpu_simple_lock_init(&alp->lock_data);
|
|
#else
|
|
alp->lock_data = __SIMPLELOCK_UNLOCKED;
|
|
#endif /* } */
|
|
alp->lock_file = NULL;
|
|
alp->lock_line = 0;
|
|
alp->unlock_file = NULL;
|
|
alp->unlock_line = 0;
|
|
alp->lock_holder = 0;
|
|
}
|
|
|
|
void
|
|
_simple_lock(alp, id, l)
|
|
__volatile struct simplelock *alp;
|
|
const char *id;
|
|
int l;
|
|
{
|
|
cpuid_t cpu_id = cpu_number();
|
|
int s;
|
|
|
|
s = splhigh();
|
|
|
|
/*
|
|
* MULTIPROCESSOR case: This is `safe' since if it's not us, we
|
|
* don't take any action, and just fall into the normal spin case.
|
|
*/
|
|
if (alp->lock_data == __SIMPLELOCK_LOCKED) {
|
|
#if defined(MULTIPROCESSOR) /* { */
|
|
if (alp->lock_holder == cpu_id) {
|
|
SLOCK_WHERE("simple_lock: locking against myself\n",
|
|
alp, id, l);
|
|
goto out;
|
|
}
|
|
#else
|
|
SLOCK_WHERE("simple_lock: lock held\n", alp, id, l);
|
|
goto out;
|
|
#endif /* MULTIPROCESSOR */ /* } */
|
|
}
|
|
|
|
#if defined(MULTIPROCESSOR) /* { */
|
|
/* Acquire the lock before modifying any fields. */
|
|
__cpu_simple_lock(&alp->lock_data);
|
|
#else
|
|
alp->lock_data = __SIMPLELOCK_LOCKED;
|
|
#endif /* } */
|
|
|
|
alp->lock_file = id;
|
|
alp->lock_line = l;
|
|
alp->lock_holder = cpu_id;
|
|
|
|
SLOCK_LIST_LOCK();
|
|
/* XXX Cast away volatile */
|
|
TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list);
|
|
SLOCK_LIST_UNLOCK();
|
|
|
|
SLOCK_COUNT(1);
|
|
|
|
out:
|
|
splx(s);
|
|
}
|
|
|
|
int
|
|
_simple_lock_try(alp, id, l)
|
|
__volatile struct simplelock *alp;
|
|
const char *id;
|
|
int l;
|
|
{
|
|
cpuid_t cpu_id = cpu_number();
|
|
int s, rv = 0;
|
|
|
|
s = splhigh();
|
|
|
|
/*
|
|
* MULTIPROCESSOR case: This is `safe' since if it's not us, we
|
|
* don't take any action.
|
|
*/
|
|
#if defined(MULTIPROCESSOR) /* { */
|
|
if ((rv = __cpu_simple_lock_try(&alp->lock_data)) == 0) {
|
|
if (alp->lock_holder == cpu_id)
|
|
SLOCK_WHERE("simple_lock_try: locking against myself\n",
|
|
alp, id, l);
|
|
goto out;
|
|
}
|
|
#else
|
|
if (alp->lock_data == __SIMPLELOCK_LOCKED) {
|
|
SLOCK_WHERE("simple_lock_try: lock held\n", alp, id, l);
|
|
goto out;
|
|
}
|
|
alp->lock_data = __SIMPLELOCK_LOCKED;
|
|
#endif /* MULTIPROCESSOR */ /* } */
|
|
|
|
/*
|
|
* At this point, we have acquired the lock.
|
|
*/
|
|
|
|
rv = 1;
|
|
|
|
alp->lock_file = id;
|
|
alp->lock_line = l;
|
|
alp->lock_holder = cpu_id;
|
|
|
|
SLOCK_LIST_LOCK();
|
|
/* XXX Cast away volatile. */
|
|
TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list);
|
|
SLOCK_LIST_UNLOCK();
|
|
|
|
SLOCK_COUNT(1);
|
|
|
|
out:
|
|
splx(s);
|
|
return (rv);
|
|
}
|
|
|
|
void
|
|
_simple_unlock(alp, id, l)
|
|
__volatile struct simplelock *alp;
|
|
const char *id;
|
|
int l;
|
|
{
|
|
int s;
|
|
|
|
s = splhigh();
|
|
|
|
/*
|
|
* MULTIPROCESSOR case: This is `safe' because we think we hold
|
|
* the lock, and if we don't, we don't take any action.
|
|
*/
|
|
if (alp->lock_data == __SIMPLELOCK_UNLOCKED) {
|
|
SLOCK_WHERE("simple_unlock: lock not held\n",
|
|
alp, id, l);
|
|
goto out;
|
|
}
|
|
|
|
SLOCK_LIST_LOCK();
|
|
TAILQ_REMOVE(&simplelock_list, alp, list);
|
|
SLOCK_LIST_UNLOCK();
|
|
|
|
SLOCK_COUNT(-1);
|
|
|
|
alp->list.tqe_next = NULL; /* sanity */
|
|
alp->list.tqe_prev = NULL; /* sanity */
|
|
|
|
alp->unlock_file = id;
|
|
alp->unlock_line = l;
|
|
|
|
#if defined(MULTIPROCESSOR) /* { */
|
|
alp->lock_holder = LK_NOCPU;
|
|
/* Now that we've modified all fields, release the lock. */
|
|
__cpu_simple_unlock(&alp->lock_data);
|
|
#else
|
|
alp->lock_data = __SIMPLELOCK_UNLOCKED;
|
|
#endif /* } */
|
|
|
|
out:
|
|
splx(s);
|
|
}
|
|
|
|
void
|
|
simple_lock_dump()
|
|
{
|
|
struct simplelock *alp;
|
|
int s;
|
|
|
|
s = splhigh();
|
|
SLOCK_LIST_LOCK();
|
|
lock_printf("all simple locks:\n");
|
|
for (alp = TAILQ_FIRST(&simplelock_list); alp != NULL;
|
|
alp = TAILQ_NEXT(alp, list)) {
|
|
lock_printf("%p CPU %lu %s:%d\n", alp, alp->lock_holder,
|
|
alp->lock_file, alp->lock_line);
|
|
}
|
|
SLOCK_LIST_UNLOCK();
|
|
splx(s);
|
|
}
|
|
|
|
void
|
|
simple_lock_freecheck(start, end)
|
|
void *start, *end;
|
|
{
|
|
struct simplelock *alp;
|
|
int s;
|
|
|
|
s = splhigh();
|
|
SLOCK_LIST_LOCK();
|
|
for (alp = TAILQ_FIRST(&simplelock_list); alp != NULL;
|
|
alp = TAILQ_NEXT(alp, list)) {
|
|
if ((void *)alp >= start && (void *)alp < end) {
|
|
lock_printf("freeing simple_lock %p CPU %lu %s:%d\n",
|
|
alp, alp->lock_holder, alp->lock_file,
|
|
alp->lock_line);
|
|
SLOCK_DEBUGGER();
|
|
}
|
|
}
|
|
SLOCK_LIST_UNLOCK();
|
|
splx(s);
|
|
}
|
|
#endif /* LOCKDEBUG */ /* } */
|