1655 lines
42 KiB
C
1655 lines
42 KiB
C
/* $NetBSD: kern_lock.c,v 1.109 2007/02/27 15:07:28 yamt Exp $ */
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/*-
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* Copyright (c) 1999, 2000, 2006 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, and by Andrew Doran.
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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
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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 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
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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 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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* @(#)kern_lock.c 8.18 (Berkeley) 5/21/95
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.109 2007/02/27 15:07:28 yamt Exp $");
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#include "opt_multiprocessor.h"
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#include "opt_ddb.h"
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#define __MUTEX_PRIVATE
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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 <sys/lockdebug.h>
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#include <machine/cpu.h>
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#include <dev/lockstat.h>
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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(const char *fmt, ...)
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__attribute__((__format__(__printf__,1,2)));
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static int acquire(volatile struct lock **, int *, int, int, int, uintptr_t);
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int lock_debug_syslog = 0; /* defaults to printf, but can be patched */
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#ifdef DDB
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#include <ddb/ddbvar.h>
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#include <machine/db_machdep.h>
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#include <ddb/db_command.h>
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#include <ddb/db_interface.h>
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#endif
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#endif /* defined(LOCKDEBUG) */
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#if defined(MULTIPROCESSOR)
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/*
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* IPL_BIGLOCK: block IPLs which need to grab kernel_mutex.
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* XXX IPL_VM or IPL_AUDIO should be enough.
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*/
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#if !defined(__HAVE_SPLBIGLOCK)
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#define splbiglock splclock
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#endif
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__cpu_simple_lock_t kernel_lock;
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int kernel_lock_id;
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#endif
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/*
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* Locking primitives implementation.
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* Locks provide shared/exclusive synchronization.
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*/
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#if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */
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#if defined(MULTIPROCESSOR) /* { */
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#define COUNT_CPU(cpu_id, x) \
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curcpu()->ci_spin_locks += (x)
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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, l, 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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(l)->l_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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#define COUNT_CPU(cpu_id, x)
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#endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */
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#define INTERLOCK_ACQUIRE(lkp, flags, s) \
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do { \
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if ((flags) & LK_SPIN) \
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s = spllock(); \
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simple_lock(&(lkp)->lk_interlock); \
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} while (/*CONSTCOND*/ 0)
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#define INTERLOCK_RELEASE(lkp, flags, s) \
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do { \
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simple_unlock(&(lkp)->lk_interlock); \
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if ((flags) & LK_SPIN) \
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splx(s); \
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} while (/*CONSTCOND*/ 0)
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#ifdef DDB /* { */
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#if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
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int simple_lock_debugger = 1; /* more serious on MP */
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#else
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int simple_lock_debugger = 0;
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#endif
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#define SLOCK_DEBUGGER() if (simple_lock_debugger && db_onpanic) Debugger()
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#define SLOCK_TRACE() \
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db_stack_trace_print((db_expr_t)__builtin_frame_address(0), \
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true, 65535, "", lock_printf);
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#else
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#define SLOCK_DEBUGGER() /* nothing */
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#define SLOCK_TRACE() /* nothing */
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#endif /* } */
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#if defined(LOCKDEBUG)
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#if defined(DDB)
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#define SPINLOCK_SPINCHECK_DEBUGGER if (db_onpanic) Debugger()
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#else
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#define SPINLOCK_SPINCHECK_DEBUGGER /* nothing */
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#endif
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#define SPINLOCK_SPINCHECK_DECL \
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/* 32-bits of count -- wrap constitutes a "spinout" */ \
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uint32_t __spinc = 0
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#define SPINLOCK_SPINCHECK \
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do { \
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if (++__spinc == 0) { \
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lock_printf("LK_SPIN spinout, excl %d, share %d\n", \
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lkp->lk_exclusivecount, lkp->lk_sharecount); \
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if (lkp->lk_exclusivecount) \
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lock_printf("held by CPU %lu\n", \
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(u_long) lkp->lk_cpu); \
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if (lkp->lk_lock_file) \
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lock_printf("last locked at %s:%d\n", \
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lkp->lk_lock_file, lkp->lk_lock_line); \
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if (lkp->lk_unlock_file) \
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lock_printf("last unlocked at %s:%d\n", \
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lkp->lk_unlock_file, lkp->lk_unlock_line); \
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SLOCK_TRACE(); \
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SPINLOCK_SPINCHECK_DEBUGGER; \
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} \
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} while (/*CONSTCOND*/ 0)
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#else
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#define SPINLOCK_SPINCHECK_DECL /* nothing */
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#define SPINLOCK_SPINCHECK /* nothing */
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#endif /* LOCKDEBUG && DDB */
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#define RETURN_ADDRESS ((uintptr_t)__builtin_return_address(0))
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/*
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* Acquire a resource.
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*/
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static int
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acquire(volatile struct lock **lkpp, int *s, int extflags,
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int drain, int wanted, uintptr_t ra)
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{
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int error;
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volatile struct lock *lkp = *lkpp;
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LOCKSTAT_TIMER(slptime);
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LOCKSTAT_FLAG(lsflag);
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KASSERT(drain || (wanted & LK_WAIT_NONZERO) == 0);
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if (extflags & LK_SPIN) {
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int interlocked;
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SPINLOCK_SPINCHECK_DECL;
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if (!drain) {
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lkp->lk_waitcount++;
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lkp->lk_flags |= LK_WAIT_NONZERO;
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}
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for (interlocked = 1;;) {
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SPINLOCK_SPINCHECK;
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if ((lkp->lk_flags & wanted) != 0) {
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if (interlocked) {
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INTERLOCK_RELEASE(lkp, LK_SPIN, *s);
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interlocked = 0;
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}
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SPINLOCK_SPIN_HOOK;
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} else if (interlocked) {
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break;
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} else {
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INTERLOCK_ACQUIRE(lkp, LK_SPIN, *s);
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interlocked = 1;
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}
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}
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if (!drain) {
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lkp->lk_waitcount--;
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if (lkp->lk_waitcount == 0)
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lkp->lk_flags &= ~LK_WAIT_NONZERO;
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}
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KASSERT((lkp->lk_flags & wanted) == 0);
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error = 0; /* sanity */
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} else {
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LOCKSTAT_ENTER(lsflag);
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for (error = 0; (lkp->lk_flags & wanted) != 0; ) {
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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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lkp->lk_flags |= LK_WAIT_NONZERO;
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}
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/* XXX Cast away volatile. */
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LOCKSTAT_START_TIMER(lsflag, slptime);
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error = ltsleep(drain ?
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(volatile const void *)&lkp->lk_flags :
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(volatile const void *)lkp, lkp->lk_prio,
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lkp->lk_wmesg, lkp->lk_timo, &lkp->lk_interlock);
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LOCKSTAT_STOP_TIMER(lsflag, slptime);
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LOCKSTAT_EVENT_RA(lsflag, (void *)(uintptr_t)lkp,
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LB_LOCKMGR | LB_SLEEP1, 1, slptime, ra);
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if (!drain) {
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lkp->lk_waitcount--;
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if (lkp->lk_waitcount == 0)
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lkp->lk_flags &= ~LK_WAIT_NONZERO;
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}
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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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if (lkp->lk_newlock != NULL) {
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simple_lock(&lkp->lk_newlock->lk_interlock);
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simple_unlock(&lkp->lk_interlock);
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if (lkp->lk_waitcount == 0)
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wakeup(&lkp->lk_newlock);
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*lkpp = lkp = lkp->lk_newlock;
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}
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}
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LOCKSTAT_EXIT(lsflag);
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}
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return error;
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}
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#define SETHOLDER(lkp, pid, lid, 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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(lkp)->lk_locklwp = lid; \
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} \
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} while (/*CONSTCOND*/0)
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#define WEHOLDIT(lkp, pid, lid, cpu_id) \
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(((lkp)->lk_flags & LK_SPIN) != 0 ? \
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((lkp)->lk_cpu == (cpu_id)) : \
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((lkp)->lk_lockholder == (pid) && (lkp)->lk_locklwp == (lid)))
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#define WAKEUP_WAITER(lkp) \
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do { \
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if (((lkp)->lk_flags & (LK_SPIN | LK_WAIT_NONZERO)) == \
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LK_WAIT_NONZERO) { \
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wakeup((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(, struct lock, volatile) 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 sp = spllock(); \
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SPINLOCK_LIST_LOCK(); \
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TAILQ_INSERT_TAIL(&spinlock_list, (lkp), lk_list); \
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SPINLOCK_LIST_UNLOCK(); \
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splx(sp); \
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} \
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} while (/*CONSTCOND*/0)
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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 sp = spllock(); \
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SPINLOCK_LIST_LOCK(); \
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TAILQ_REMOVE(&spinlock_list, (lkp), lk_list); \
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SPINLOCK_LIST_UNLOCK(); \
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splx(sp); \
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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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#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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lock_printf(const char *fmt, ...)
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{
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char b[150];
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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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vsnprintf(b, sizeof(b), fmt, ap);
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printf_nolog("%s", b);
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}
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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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* Transfer any waiting processes from one lock to another.
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*/
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void
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transferlockers(struct lock *from, struct lock *to)
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{
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KASSERT(from != to);
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KASSERT((from->lk_flags & LK_WAITDRAIN) == 0);
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if (from->lk_waitcount == 0)
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return;
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from->lk_newlock = to;
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wakeup((void *)from);
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tsleep((void *)&from->lk_newlock, from->lk_prio, "lkxfer", 0);
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from->lk_newlock = NULL;
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from->lk_flags &= ~(LK_WANT_EXCL | LK_WANT_UPGRADE);
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KASSERT(from->lk_waitcount == 0);
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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(struct lock *lkp, pri_t prio, const char *wmesg, int timo, 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_newlock = NULL;
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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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#if defined(LOCKDEBUG)
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lkp->lk_lock_file = NULL;
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lkp->lk_unlock_file = NULL;
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#endif
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}
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|
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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(struct lock *lkp)
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{
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int s = 0; /* XXX: gcc */
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int lock_type = 0;
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struct lwp *l = curlwp; /* XXX */
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pid_t pid;
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lwpid_t lid;
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cpuid_t cpu_num;
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if ((lkp->lk_flags & LK_SPIN) || l == NULL) {
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cpu_num = cpu_number();
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pid = LK_KERNPROC;
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lid = 0;
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} else {
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cpu_num = LK_NOCPU;
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pid = l->l_proc->p_pid;
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lid = l->l_lid;
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}
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INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s);
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if (lkp->lk_exclusivecount != 0) {
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if (WEHOLDIT(lkp, pid, lid, cpu_num))
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lock_type = LK_EXCLUSIVE;
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else
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lock_type = LK_EXCLOTHER;
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} else if (lkp->lk_sharecount != 0)
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lock_type = LK_SHARED;
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else if (lkp->lk_flags & (LK_WANT_EXCL | LK_WANT_UPGRADE))
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lock_type = LK_EXCLOTHER;
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INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
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return (lock_type);
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}
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#if defined(LOCKDEBUG)
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/*
|
|
* Make sure no spin locks are held by a CPU that is about
|
|
* to context switch.
|
|
*/
|
|
void
|
|
spinlock_switchcheck(void)
|
|
{
|
|
u_long cnt;
|
|
int s;
|
|
|
|
s = spllock();
|
|
#if defined(MULTIPROCESSOR)
|
|
cnt = curcpu()->ci_spin_locks;
|
|
#else
|
|
cnt = spin_locks;
|
|
#endif
|
|
splx(s);
|
|
|
|
if (cnt != 0)
|
|
panic("spinlock_switchcheck: CPU %lu has %lu spin locks",
|
|
(u_long) cpu_number(), cnt);
|
|
}
|
|
#endif /* LOCKDEBUG */
|
|
|
|
/*
|
|
* Locks and IPLs (interrupt priority levels):
|
|
*
|
|
* Locks which may be taken from interrupt context must be handled
|
|
* very carefully; you must spl to the highest IPL where the lock
|
|
* is needed before acquiring the lock.
|
|
*
|
|
* It is also important to avoid deadlock, since certain (very high
|
|
* priority) interrupts are often needed to keep the system as a whole
|
|
* from deadlocking, and must not be blocked while you are spinning
|
|
* waiting for a lower-priority lock.
|
|
*
|
|
* In addition, the lock-debugging hooks themselves need to use locks!
|
|
*
|
|
* A raw __cpu_simple_lock may be used from interrupts are long as it
|
|
* is acquired and held at a single IPL.
|
|
*
|
|
* A simple_lock (which is a __cpu_simple_lock wrapped with some
|
|
* debugging hooks) may be used at or below spllock(), which is
|
|
* typically at or just below splhigh() (i.e. blocks everything
|
|
* but certain machine-dependent extremely high priority interrupts).
|
|
*
|
|
* spinlockmgr spinlocks should be used at or below splsched().
|
|
*
|
|
* Some platforms may have interrupts of higher priority than splsched(),
|
|
* including hard serial interrupts, inter-processor interrupts, and
|
|
* kernel debugger traps.
|
|
*/
|
|
|
|
/*
|
|
* XXX XXX kludge around another kludge..
|
|
*
|
|
* vfs_shutdown() may be called from interrupt context, either as a result
|
|
* of a panic, or from the debugger. It proceeds to call
|
|
* sys_sync(&proc0, ...), pretending its running on behalf of proc0
|
|
*
|
|
* 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.
|
|
* All locks are acquired on behalf of proc0.
|
|
*
|
|
* If we've already paniced, we don't block waiting for locks, but
|
|
* just barge right ahead since we're already going down in flames.
|
|
*/
|
|
|
|
/*
|
|
* Set, change, or release a lock.
|
|
*
|
|
* Shared requests increment the shared count. Exclusive requests set the
|
|
* LK_WANT_EXCL flag (preventing further shared locks), and wait for already
|
|
* accepted shared locks and shared-to-exclusive upgrades to go away.
|
|
*/
|
|
int
|
|
#if defined(LOCKDEBUG)
|
|
_lockmgr(volatile struct lock *lkp, u_int flags,
|
|
struct simplelock *interlkp, const char *file, int line)
|
|
#else
|
|
lockmgr(volatile struct lock *lkp, u_int flags,
|
|
struct simplelock *interlkp)
|
|
#endif
|
|
{
|
|
int error;
|
|
pid_t pid;
|
|
lwpid_t lid;
|
|
int extflags;
|
|
cpuid_t cpu_num;
|
|
struct lwp *l = curlwp;
|
|
int lock_shutdown_noblock = 0;
|
|
int s = 0;
|
|
|
|
error = 0;
|
|
|
|
/* LK_RETRY is for vn_lock, not for lockmgr. */
|
|
KASSERT((flags & LK_RETRY) == 0);
|
|
|
|
INTERLOCK_ACQUIRE(lkp, lkp->lk_flags, s);
|
|
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");
|
|
#endif /* } */
|
|
|
|
if (extflags & LK_SPIN) {
|
|
pid = LK_KERNPROC;
|
|
lid = 0;
|
|
} else {
|
|
if (l == NULL) {
|
|
if (!doing_shutdown) {
|
|
panic("lockmgr: no context");
|
|
} else {
|
|
l = &lwp0;
|
|
if (panicstr && (!(flags & LK_NOWAIT))) {
|
|
flags |= LK_NOWAIT;
|
|
lock_shutdown_noblock = 1;
|
|
}
|
|
}
|
|
}
|
|
lid = l->l_lid;
|
|
pid = l->l_proc->p_pid;
|
|
}
|
|
cpu_num = 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, lid, cpu_num) == 0)
|
|
panic("lockmgr: non-release on draining lock: %d",
|
|
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, lid, cpu_num) == 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.
|
|
*/
|
|
error = acquire(&lkp, &s, extflags, 0,
|
|
LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE,
|
|
RETURN_ADDRESS);
|
|
if (error)
|
|
break;
|
|
lkp->lk_sharecount++;
|
|
lkp->lk_flags |= LK_SHARE_NONZERO;
|
|
COUNT(lkp, l, cpu_num, 1);
|
|
break;
|
|
}
|
|
/*
|
|
* We hold an exclusive lock, so downgrade it to shared.
|
|
* An alternative would be to fail with EDEADLK.
|
|
*/
|
|
lkp->lk_sharecount++;
|
|
lkp->lk_flags |= LK_SHARE_NONZERO;
|
|
COUNT(lkp, l, cpu_num, 1);
|
|
/* fall into downgrade */
|
|
|
|
case LK_DOWNGRADE:
|
|
if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0 ||
|
|
lkp->lk_exclusivecount == 0)
|
|
panic("lockmgr: not holding exclusive lock");
|
|
lkp->lk_sharecount += lkp->lk_exclusivecount;
|
|
lkp->lk_flags |= LK_SHARE_NONZERO;
|
|
lkp->lk_exclusivecount = 0;
|
|
lkp->lk_recurselevel = 0;
|
|
lkp->lk_flags &= ~LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU);
|
|
#if defined(LOCKDEBUG)
|
|
lkp->lk_unlock_file = file;
|
|
lkp->lk_unlock_line = line;
|
|
#endif
|
|
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--;
|
|
if (lkp->lk_sharecount == 0)
|
|
lkp->lk_flags &= ~LK_SHARE_NONZERO;
|
|
COUNT(lkp, l, cpu_num, -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, lid, cpu_num) || lkp->lk_sharecount <= 0)
|
|
panic("lockmgr: upgrade exclusive lock");
|
|
lkp->lk_sharecount--;
|
|
if (lkp->lk_sharecount == 0)
|
|
lkp->lk_flags &= ~LK_SHARE_NONZERO;
|
|
COUNT(lkp, l, cpu_num, -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;
|
|
error = acquire(&lkp, &s, extflags, 0, LK_SHARE_NONZERO,
|
|
RETURN_ADDRESS);
|
|
lkp->lk_flags &= ~LK_WANT_UPGRADE;
|
|
if (error) {
|
|
WAKEUP_WAITER(lkp);
|
|
break;
|
|
}
|
|
lkp->lk_flags |= LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, pid, lid, cpu_num);
|
|
#if defined(LOCKDEBUG)
|
|
lkp->lk_lock_file = file;
|
|
lkp->lk_lock_line = line;
|
|
#endif
|
|
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, l, cpu_num, 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, lid, cpu_num)) {
|
|
/*
|
|
* 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, l, cpu_num, 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 |
|
|
LK_SHARE_NONZERO))) {
|
|
error = EBUSY;
|
|
break;
|
|
}
|
|
/*
|
|
* Try to acquire the want_exclusive flag.
|
|
*/
|
|
error = acquire(&lkp, &s, extflags, 0,
|
|
LK_HAVE_EXCL | LK_WANT_EXCL, RETURN_ADDRESS);
|
|
if (error)
|
|
break;
|
|
lkp->lk_flags |= LK_WANT_EXCL;
|
|
/*
|
|
* Wait for shared locks and upgrades to finish.
|
|
*/
|
|
error = acquire(&lkp, &s, extflags, 0,
|
|
LK_HAVE_EXCL | LK_WANT_UPGRADE | LK_SHARE_NONZERO,
|
|
RETURN_ADDRESS);
|
|
lkp->lk_flags &= ~LK_WANT_EXCL;
|
|
if (error) {
|
|
WAKEUP_WAITER(lkp);
|
|
break;
|
|
}
|
|
lkp->lk_flags |= LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, pid, lid, cpu_num);
|
|
#if defined(LOCKDEBUG)
|
|
lkp->lk_lock_file = file;
|
|
lkp->lk_lock_line = line;
|
|
#endif
|
|
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, l, cpu_num, 1);
|
|
break;
|
|
|
|
case LK_RELEASE:
|
|
if (lkp->lk_exclusivecount != 0) {
|
|
if (WEHOLDIT(lkp, pid, lid, cpu_num) == 0) {
|
|
if (lkp->lk_flags & LK_SPIN) {
|
|
panic("lockmgr: processor %lu, not "
|
|
"exclusive lock holder %lu "
|
|
"unlocking", cpu_num, 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, l, cpu_num, -1);
|
|
if (lkp->lk_exclusivecount == 0) {
|
|
lkp->lk_flags &= ~LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU);
|
|
#if defined(LOCKDEBUG)
|
|
lkp->lk_unlock_file = file;
|
|
lkp->lk_unlock_line = line;
|
|
#endif
|
|
DONTHAVEIT(lkp);
|
|
}
|
|
} else if (lkp->lk_sharecount != 0) {
|
|
lkp->lk_sharecount--;
|
|
if (lkp->lk_sharecount == 0)
|
|
lkp->lk_flags &= ~LK_SHARE_NONZERO;
|
|
COUNT(lkp, l, cpu_num, -1);
|
|
}
|
|
#ifdef DIAGNOSTIC
|
|
else
|
|
panic("lockmgr: release of unlocked lock!");
|
|
#endif
|
|
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, lid, cpu_num))
|
|
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 |
|
|
LK_SHARE_NONZERO | LK_WAIT_NONZERO))) {
|
|
error = EBUSY;
|
|
break;
|
|
}
|
|
error = acquire(&lkp, &s, extflags, 1,
|
|
LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE |
|
|
LK_SHARE_NONZERO | LK_WAIT_NONZERO,
|
|
RETURN_ADDRESS);
|
|
if (error)
|
|
break;
|
|
lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, pid, lid, cpu_num);
|
|
#if defined(LOCKDEBUG)
|
|
lkp->lk_lock_file = file;
|
|
lkp->lk_lock_line = line;
|
|
#endif
|
|
HAVEIT(lkp);
|
|
lkp->lk_exclusivecount = 1;
|
|
/* XXX unlikely that we'd want this */
|
|
if (extflags & LK_SETRECURSE)
|
|
lkp->lk_recurselevel = 1;
|
|
COUNT(lkp, l, cpu_num, 1);
|
|
break;
|
|
|
|
default:
|
|
INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
|
|
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 |
|
|
LK_SHARE_NONZERO | LK_WAIT_NONZERO)) == 0)) {
|
|
lkp->lk_flags &= ~LK_WAITDRAIN;
|
|
wakeup(&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)");
|
|
|
|
INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* For a recursive spinlock held one or more times by the current CPU,
|
|
* release all N locks, and return N.
|
|
* Intended for use in mi_switch() shortly before context switching.
|
|
*/
|
|
|
|
int
|
|
#if defined(LOCKDEBUG)
|
|
_spinlock_release_all(volatile struct lock *lkp, const char *file, int line)
|
|
#else
|
|
spinlock_release_all(volatile struct lock *lkp)
|
|
#endif
|
|
{
|
|
int s, count;
|
|
cpuid_t cpu_num;
|
|
|
|
KASSERT(lkp->lk_flags & LK_SPIN);
|
|
|
|
INTERLOCK_ACQUIRE(lkp, LK_SPIN, s);
|
|
|
|
cpu_num = cpu_number();
|
|
count = lkp->lk_exclusivecount;
|
|
|
|
if (count != 0) {
|
|
#ifdef DIAGNOSTIC
|
|
if (WEHOLDIT(lkp, 0, 0, cpu_num) == 0) {
|
|
panic("spinlock_release_all: processor %lu, not "
|
|
"exclusive lock holder %lu "
|
|
"unlocking", (long)cpu_num, lkp->lk_cpu);
|
|
}
|
|
#endif
|
|
lkp->lk_recurselevel = 0;
|
|
lkp->lk_exclusivecount = 0;
|
|
COUNT_CPU(cpu_num, -count);
|
|
lkp->lk_flags &= ~LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, LK_NOPROC, 0, LK_NOCPU);
|
|
#if defined(LOCKDEBUG)
|
|
lkp->lk_unlock_file = file;
|
|
lkp->lk_unlock_line = line;
|
|
#endif
|
|
DONTHAVEIT(lkp);
|
|
}
|
|
#ifdef DIAGNOSTIC
|
|
else if (lkp->lk_sharecount != 0)
|
|
panic("spinlock_release_all: release of shared lock!");
|
|
else
|
|
panic("spinlock_release_all: release of unlocked lock!");
|
|
#endif
|
|
INTERLOCK_RELEASE(lkp, LK_SPIN, s);
|
|
|
|
return (count);
|
|
}
|
|
|
|
/*
|
|
* For a recursive spinlock held one or more times by the current CPU,
|
|
* release all N locks, and return N.
|
|
* Intended for use in mi_switch() right after resuming execution.
|
|
*/
|
|
|
|
void
|
|
#if defined(LOCKDEBUG)
|
|
_spinlock_acquire_count(volatile struct lock *lkp, int count,
|
|
const char *file, int line)
|
|
#else
|
|
spinlock_acquire_count(volatile struct lock *lkp, int count)
|
|
#endif
|
|
{
|
|
int s, error;
|
|
cpuid_t cpu_num;
|
|
|
|
KASSERT(lkp->lk_flags & LK_SPIN);
|
|
|
|
INTERLOCK_ACQUIRE(lkp, LK_SPIN, s);
|
|
|
|
cpu_num = cpu_number();
|
|
|
|
#ifdef DIAGNOSTIC
|
|
if (WEHOLDIT(lkp, LK_NOPROC, 0, cpu_num))
|
|
panic("spinlock_acquire_count: processor %lu already holds lock", (long)cpu_num);
|
|
#endif
|
|
/*
|
|
* Try to acquire the want_exclusive flag.
|
|
*/
|
|
error = acquire(&lkp, &s, LK_SPIN, 0, LK_HAVE_EXCL | LK_WANT_EXCL,
|
|
RETURN_ADDRESS);
|
|
lkp->lk_flags |= LK_WANT_EXCL;
|
|
/*
|
|
* Wait for shared locks and upgrades to finish.
|
|
*/
|
|
error = acquire(&lkp, &s, LK_SPIN, 0,
|
|
LK_HAVE_EXCL | LK_SHARE_NONZERO | LK_WANT_UPGRADE,
|
|
RETURN_ADDRESS);
|
|
lkp->lk_flags &= ~LK_WANT_EXCL;
|
|
lkp->lk_flags |= LK_HAVE_EXCL;
|
|
SETHOLDER(lkp, LK_NOPROC, 0, cpu_num);
|
|
#if defined(LOCKDEBUG)
|
|
lkp->lk_lock_file = file;
|
|
lkp->lk_lock_line = line;
|
|
#endif
|
|
HAVEIT(lkp);
|
|
if (lkp->lk_exclusivecount != 0)
|
|
panic("lockmgr: non-zero exclusive count");
|
|
lkp->lk_exclusivecount = count;
|
|
lkp->lk_recurselevel = 1;
|
|
COUNT_CPU(cpu_num, count);
|
|
|
|
INTERLOCK_RELEASE(lkp, lkp->lk_flags, s);
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* Print out information about state of a lock. Used by VOP_PRINT
|
|
* routines to display ststus about contained locks.
|
|
*/
|
|
void
|
|
lockmgr_printinfo(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.%d", lkp->lk_lockholder,
|
|
lkp->lk_locklwp);
|
|
} 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(, struct simplelock, volatile) 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)
|
|
|
|
#define SLOCK_COUNT(x) \
|
|
curcpu()->ci_simple_locks += (x)
|
|
#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 MULTIPROCESSOR
|
|
#define SLOCK_MP() lock_printf("on CPU %ld\n", \
|
|
(u_long) cpu_number())
|
|
#else
|
|
#define SLOCK_MP() /* nothing */
|
|
#endif
|
|
|
|
#define SLOCK_WHERE(str, alp, id, l) \
|
|
do { \
|
|
lock_printf("\n"); \
|
|
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_TRACE() \
|
|
SLOCK_DEBUGGER(); \
|
|
} while (/*CONSTCOND*/0)
|
|
|
|
/*
|
|
* Simple lock functions so that the debugger can see from whence
|
|
* they are being called.
|
|
*/
|
|
void
|
|
simple_lock_init(volatile 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 = LK_NOCPU;
|
|
}
|
|
|
|
void
|
|
_simple_lock(volatile struct simplelock *alp, const char *id, int l)
|
|
{
|
|
cpuid_t cpu_num = cpu_number();
|
|
int s;
|
|
|
|
s = spllock();
|
|
|
|
/*
|
|
* 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_num) {
|
|
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. */
|
|
splx(s);
|
|
__cpu_simple_lock(&alp->lock_data);
|
|
s = spllock();
|
|
#else
|
|
alp->lock_data = __SIMPLELOCK_LOCKED;
|
|
#endif /* } */
|
|
|
|
if (alp->lock_holder != LK_NOCPU) {
|
|
SLOCK_WHERE("simple_lock: uninitialized lock\n",
|
|
alp, id, l);
|
|
}
|
|
alp->lock_file = id;
|
|
alp->lock_line = l;
|
|
alp->lock_holder = cpu_num;
|
|
|
|
SLOCK_LIST_LOCK();
|
|
TAILQ_INSERT_TAIL(&simplelock_list, alp, list);
|
|
SLOCK_LIST_UNLOCK();
|
|
|
|
SLOCK_COUNT(1);
|
|
|
|
out:
|
|
splx(s);
|
|
}
|
|
|
|
int
|
|
_simple_lock_held(volatile struct simplelock *alp)
|
|
{
|
|
#if defined(MULTIPROCESSOR) || defined(DIAGNOSTIC)
|
|
cpuid_t cpu_num = cpu_number();
|
|
#endif
|
|
int s, locked = 0;
|
|
|
|
s = spllock();
|
|
|
|
#if defined(MULTIPROCESSOR)
|
|
if (__cpu_simple_lock_try(&alp->lock_data) == 0)
|
|
locked = (alp->lock_holder == cpu_num);
|
|
else
|
|
__cpu_simple_unlock(&alp->lock_data);
|
|
#else
|
|
if (alp->lock_data == __SIMPLELOCK_LOCKED) {
|
|
locked = 1;
|
|
KASSERT(alp->lock_holder == cpu_num);
|
|
}
|
|
#endif
|
|
|
|
splx(s);
|
|
|
|
return (locked);
|
|
}
|
|
|
|
int
|
|
_simple_lock_try(volatile struct simplelock *alp, const char *id, int l)
|
|
{
|
|
cpuid_t cpu_num = cpu_number();
|
|
int s, rv = 0;
|
|
|
|
s = spllock();
|
|
|
|
/*
|
|
* 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_num)
|
|
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_num;
|
|
|
|
SLOCK_LIST_LOCK();
|
|
TAILQ_INSERT_TAIL(&simplelock_list, alp, list);
|
|
SLOCK_LIST_UNLOCK();
|
|
|
|
SLOCK_COUNT(1);
|
|
|
|
out:
|
|
splx(s);
|
|
return (rv);
|
|
}
|
|
|
|
void
|
|
_simple_unlock(volatile struct simplelock *alp, const char *id, int l)
|
|
{
|
|
int s;
|
|
|
|
s = spllock();
|
|
|
|
/*
|
|
* 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;
|
|
KASSERT(alp->lock_holder == cpu_number());
|
|
alp->lock_holder = LK_NOCPU;
|
|
#endif /* } */
|
|
|
|
out:
|
|
splx(s);
|
|
}
|
|
|
|
void
|
|
simple_lock_dump(void)
|
|
{
|
|
volatile struct simplelock *alp;
|
|
int s;
|
|
|
|
s = spllock();
|
|
SLOCK_LIST_LOCK();
|
|
lock_printf("all simple locks:\n");
|
|
TAILQ_FOREACH(alp, &simplelock_list, 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(void *start, void *end)
|
|
{
|
|
volatile struct simplelock *alp;
|
|
int s;
|
|
|
|
s = spllock();
|
|
SLOCK_LIST_LOCK();
|
|
TAILQ_FOREACH(alp, &simplelock_list, list) {
|
|
if ((volatile void *)alp >= start &&
|
|
(volatile 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);
|
|
}
|
|
|
|
/*
|
|
* We must be holding exactly one lock: the sched_lock.
|
|
*/
|
|
|
|
void
|
|
simple_lock_switchcheck(void)
|
|
{
|
|
|
|
simple_lock_only_held(NULL, "switching");
|
|
}
|
|
|
|
/*
|
|
* Drop into the debugger if lp isn't the only lock held.
|
|
* lp may be NULL.
|
|
*/
|
|
void
|
|
simple_lock_only_held(volatile struct simplelock *lp, const char *where)
|
|
{
|
|
volatile struct simplelock *alp;
|
|
cpuid_t cpu_num = cpu_number();
|
|
int s;
|
|
|
|
if (lp) {
|
|
LOCK_ASSERT(simple_lock_held(lp));
|
|
}
|
|
s = spllock();
|
|
SLOCK_LIST_LOCK();
|
|
TAILQ_FOREACH(alp, &simplelock_list, list) {
|
|
if (alp == lp)
|
|
continue;
|
|
if (alp->lock_holder == cpu_num)
|
|
break;
|
|
}
|
|
SLOCK_LIST_UNLOCK();
|
|
splx(s);
|
|
|
|
if (alp != NULL) {
|
|
lock_printf("\n%s with held simple_lock %p "
|
|
"CPU %lu %s:%d\n",
|
|
where, alp, alp->lock_holder, alp->lock_file,
|
|
alp->lock_line);
|
|
SLOCK_TRACE();
|
|
SLOCK_DEBUGGER();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Set to 1 by simple_lock_assert_*().
|
|
* Can be cleared from ddb to avoid a panic.
|
|
*/
|
|
int slock_assert_will_panic;
|
|
|
|
/*
|
|
* If the lock isn't held, print a traceback, optionally drop into the
|
|
* debugger, then panic.
|
|
* The panic can be avoided by clearing slock_assert_with_panic from the
|
|
* debugger.
|
|
*/
|
|
void
|
|
_simple_lock_assert_locked(volatile struct simplelock *alp,
|
|
const char *lockname, const char *id, int l)
|
|
{
|
|
if (simple_lock_held(alp) == 0) {
|
|
slock_assert_will_panic = 1;
|
|
lock_printf("%s lock not held\n", lockname);
|
|
SLOCK_WHERE("lock not held", alp, id, l);
|
|
if (slock_assert_will_panic)
|
|
panic("%s: not locked", lockname);
|
|
}
|
|
}
|
|
|
|
void
|
|
_simple_lock_assert_unlocked(volatile struct simplelock *alp,
|
|
const char *lockname, const char *id, int l)
|
|
{
|
|
if (simple_lock_held(alp)) {
|
|
slock_assert_will_panic = 1;
|
|
lock_printf("%s lock held\n", lockname);
|
|
SLOCK_WHERE("lock held", alp, id, l);
|
|
if (slock_assert_will_panic)
|
|
panic("%s: locked", lockname);
|
|
}
|
|
}
|
|
|
|
void
|
|
assert_sleepable(struct simplelock *interlock, const char *msg)
|
|
{
|
|
|
|
if (curlwp == NULL) {
|
|
panic("assert_sleepable: NULL curlwp");
|
|
}
|
|
simple_lock_only_held(interlock, msg);
|
|
}
|
|
|
|
#endif /* LOCKDEBUG */ /* } */
|
|
|
|
#if defined(MULTIPROCESSOR)
|
|
|
|
/*
|
|
* Functions for manipulating the kernel_lock. We put them here
|
|
* so that they show up in profiles.
|
|
*/
|
|
|
|
#define _KERNEL_LOCK_ABORT(msg) \
|
|
LOCKDEBUG_ABORT(kernel_lock_id, &kernel_lock, &_kernel_lock_ops, \
|
|
__FUNCTION__, msg)
|
|
|
|
#ifdef LOCKDEBUG
|
|
#define _KERNEL_LOCK_ASSERT(cond) \
|
|
do { \
|
|
if (!(cond)) \
|
|
_KERNEL_LOCK_ABORT("assertion failed: " #cond); \
|
|
} while (/* CONSTCOND */ 0)
|
|
#else
|
|
#define _KERNEL_LOCK_ASSERT(cond) /* nothing */
|
|
#endif
|
|
|
|
void _kernel_lock_dump(volatile void *);
|
|
|
|
lockops_t _kernel_lock_ops = {
|
|
"Kernel lock",
|
|
0,
|
|
_kernel_lock_dump
|
|
};
|
|
|
|
/*
|
|
* Initialize the kernel lock.
|
|
*/
|
|
void
|
|
_kernel_lock_init(void)
|
|
{
|
|
|
|
__cpu_simple_lock_init(&kernel_lock);
|
|
kernel_lock_id = LOCKDEBUG_ALLOC(&kernel_lock, &_kernel_lock_ops);
|
|
}
|
|
|
|
/*
|
|
* Print debugging information about the kernel lock.
|
|
*/
|
|
void
|
|
_kernel_lock_dump(volatile void *junk)
|
|
{
|
|
struct cpu_info *ci = curcpu();
|
|
|
|
(void)junk;
|
|
|
|
printf_nolog("curcpu holds : %18d wanted by: %#018lx\n",
|
|
ci->ci_biglock_count, (long)ci->ci_biglock_wanted);
|
|
}
|
|
|
|
/*
|
|
* Acquire 'nlocks' holds on the kernel lock. If 'l' is non-null, the
|
|
* acquisition is from process context.
|
|
*/
|
|
void
|
|
_kernel_lock(int nlocks, struct lwp *l)
|
|
{
|
|
struct cpu_info *ci = curcpu();
|
|
LOCKSTAT_TIMER(spintime);
|
|
LOCKSTAT_FLAG(lsflag);
|
|
struct lwp *owant;
|
|
#ifdef LOCKDEBUG
|
|
u_int spins;
|
|
#endif
|
|
int s;
|
|
|
|
(void)l;
|
|
|
|
if (nlocks == 0)
|
|
return;
|
|
_KERNEL_LOCK_ASSERT(nlocks > 0);
|
|
|
|
s = splbiglock();
|
|
|
|
if (ci->ci_biglock_count != 0) {
|
|
_KERNEL_LOCK_ASSERT(kernel_lock == __SIMPLELOCK_LOCKED);
|
|
ci->ci_biglock_count += nlocks;
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
LOCKDEBUG_WANTLOCK(kernel_lock_id,
|
|
(uintptr_t)__builtin_return_address(0), 0);
|
|
|
|
if (__cpu_simple_lock_try(&kernel_lock)) {
|
|
ci->ci_biglock_count = nlocks;
|
|
LOCKDEBUG_LOCKED(kernel_lock_id,
|
|
(uintptr_t)__builtin_return_address(0), 0);
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
LOCKSTAT_ENTER(lsflag);
|
|
LOCKSTAT_START_TIMER(lsflag, spintime);
|
|
|
|
/*
|
|
* Before setting ci_biglock_wanted we must post a store
|
|
* fence (see kern_mutex.c). This is accomplished by the
|
|
* __cpu_simple_lock_try() above.
|
|
*/
|
|
owant = ci->ci_biglock_wanted;
|
|
ci->ci_biglock_wanted = curlwp; /* XXXAD */
|
|
|
|
#ifdef LOCKDEBUG
|
|
spins = 0;
|
|
#endif
|
|
|
|
do {
|
|
while (kernel_lock == __SIMPLELOCK_LOCKED) {
|
|
#ifdef LOCKDEBUG
|
|
if (SPINLOCK_SPINOUT(spins))
|
|
_KERNEL_LOCK_ABORT("spinout");
|
|
#endif
|
|
splx(s);
|
|
SPINLOCK_SPIN_HOOK;
|
|
(void)splbiglock();
|
|
}
|
|
} while (!__cpu_simple_lock_try(&kernel_lock));
|
|
|
|
ci->ci_biglock_wanted = owant;
|
|
ci->ci_biglock_count += nlocks;
|
|
LOCKSTAT_STOP_TIMER(lsflag, spintime);
|
|
LOCKDEBUG_LOCKED(kernel_lock_id,
|
|
(uintptr_t)__builtin_return_address(0), 0);
|
|
splx(s);
|
|
|
|
/*
|
|
* Again, another store fence is required (see kern_mutex.c).
|
|
*/
|
|
mb_write();
|
|
if (owant == NULL) {
|
|
LOCKSTAT_EVENT(lsflag, &kernel_lock, LB_KERNEL_LOCK | LB_SPIN,
|
|
1, spintime);
|
|
}
|
|
LOCKSTAT_EXIT(lsflag);
|
|
}
|
|
|
|
/*
|
|
* Release 'nlocks' holds on the kernel lock. If 'nlocks' is zero, release
|
|
* all holds. If 'l' is non-null, the release is from process context.
|
|
*/
|
|
void
|
|
_kernel_unlock(int nlocks, struct lwp *l, int *countp)
|
|
{
|
|
struct cpu_info *ci = curcpu();
|
|
u_int olocks;
|
|
int s;
|
|
|
|
(void)l;
|
|
|
|
_KERNEL_LOCK_ASSERT(nlocks < 2);
|
|
|
|
olocks = ci->ci_biglock_count;
|
|
|
|
if (olocks == 0) {
|
|
_KERNEL_LOCK_ASSERT(nlocks <= 0);
|
|
if (countp != NULL)
|
|
*countp = 0;
|
|
return;
|
|
}
|
|
|
|
_KERNEL_LOCK_ASSERT(kernel_lock == __SIMPLELOCK_LOCKED);
|
|
|
|
if (nlocks == 0)
|
|
nlocks = olocks;
|
|
else if (nlocks == -1) {
|
|
nlocks = 1;
|
|
_KERNEL_LOCK_ASSERT(olocks == 1);
|
|
}
|
|
|
|
s = splbiglock();
|
|
if ((ci->ci_biglock_count -= nlocks) == 0) {
|
|
LOCKDEBUG_UNLOCKED(kernel_lock_id,
|
|
(uintptr_t)__builtin_return_address(0), 0);
|
|
__cpu_simple_unlock(&kernel_lock);
|
|
}
|
|
splx(s);
|
|
|
|
if (countp != NULL)
|
|
*countp = olocks;
|
|
}
|
|
|
|
#if defined(DEBUG)
|
|
/*
|
|
* Assert that the kernel lock is held.
|
|
*/
|
|
void
|
|
_kernel_lock_assert_locked(void)
|
|
{
|
|
|
|
if (kernel_lock != __SIMPLELOCK_LOCKED ||
|
|
curcpu()->ci_biglock_count == 0)
|
|
_KERNEL_LOCK_ABORT("not locked");
|
|
}
|
|
|
|
void
|
|
_kernel_lock_assert_unlocked()
|
|
{
|
|
|
|
if (curcpu()->ci_biglock_count != 0)
|
|
_KERNEL_LOCK_ABORT("locked");
|
|
}
|
|
#endif
|
|
|
|
#endif /* MULTIPROCESSOR || LOCKDEBUG */
|