102 lines
3.0 KiB
C
102 lines
3.0 KiB
C
/* $NetBSD: kern_cfglock.c,v 1.1 2010/08/21 13:17:31 pgoyette Exp $ */
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/*-
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* Copyright (c) 2002, 2006, 2007, 2008, 2009 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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* 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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*
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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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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_cfglock.c,v 1.1 2010/08/21 13:17:31 pgoyette Exp $");
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#include <sys/param.h>
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#include <sys/cpu.h>
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#include <sys/mutex.h>
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#include <sys/lwp.h>
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#include <sys/systm.h>
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static kmutex_t kernconfig_mutex;
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static lwp_t *kernconfig_lwp;
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static int kernconfig_recurse;
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/*
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* Functions for manipulating the kernel configuration lock. This
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* recursive lock should be used to protect all additions and removals
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* of kernel functionality, such as device configuration and loading
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* of modular kernel components.
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*/
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void
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kernconfig_lock_init(void)
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{
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mutex_init(&kernconfig_mutex, MUTEX_DEFAULT, IPL_NONE);
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kernconfig_lwp = NULL;
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kernconfig_recurse = 0;
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}
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void
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kernconfig_lock(void)
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{
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lwp_t *my_lwp;
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/*
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* It's OK to check this unlocked, since it could only be set to
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* curlwp by the current thread itself, and not by an interrupt
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* or any other LWP.
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*/
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KASSERT(!cpu_intr_p());
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my_lwp = curlwp;
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if (kernconfig_lwp == my_lwp) {
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kernconfig_recurse++;
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KASSERT(kernconfig_recurse > 1);
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} else {
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mutex_enter(&kernconfig_mutex);
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kernconfig_lwp = my_lwp;
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kernconfig_recurse = 1;
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}
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}
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void
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kernconfig_unlock(void)
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{
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KASSERT(kernconfig_is_held());
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KASSERT(kernconfig_recurse != 0);
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if (--kernconfig_recurse == 0) {
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kernconfig_lwp = NULL;
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mutex_exit(&kernconfig_mutex);
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}
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}
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bool
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kernconfig_is_held(void)
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{
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return mutex_owned(&kernconfig_mutex);
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}
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