kern_cfglock.c revision 1.1.2.2
1 1.1.2.2 yamt /* $NetBSD: kern_cfglock.c,v 1.1.2.2 2010/10/09 03:32:30 yamt Exp $ */ 2 1.1.2.2 yamt 3 1.1.2.2 yamt /*- 4 1.1.2.2 yamt * Copyright (c) 2002, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc. 5 1.1.2.2 yamt * All rights reserved. 6 1.1.2.2 yamt * 7 1.1.2.2 yamt * This code is derived from software contributed to The NetBSD Foundation 8 1.1.2.2 yamt * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 1.1.2.2 yamt * NASA Ames Research Center, and by Andrew Doran. 10 1.1.2.2 yamt * 11 1.1.2.2 yamt * Redistribution and use in source and binary forms, with or without 12 1.1.2.2 yamt * modification, are permitted provided that the following conditions 13 1.1.2.2 yamt * are met: 14 1.1.2.2 yamt * 1. Redistributions of source code must retain the above copyright 15 1.1.2.2 yamt * notice, this list of conditions and the following disclaimer. 16 1.1.2.2 yamt * 2. Redistributions in binary form must reproduce the above copyright 17 1.1.2.2 yamt * notice, this list of conditions and the following disclaimer in the 18 1.1.2.2 yamt * documentation and/or other materials provided with the distribution. 19 1.1.2.2 yamt * 20 1.1.2.2 yamt * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 1.1.2.2 yamt * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 1.1.2.2 yamt * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 1.1.2.2 yamt * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 1.1.2.2 yamt * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 1.1.2.2 yamt * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 1.1.2.2 yamt * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 1.1.2.2 yamt * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 1.1.2.2 yamt * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 1.1.2.2 yamt * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 1.1.2.2 yamt * POSSIBILITY OF SUCH DAMAGE. 31 1.1.2.2 yamt */ 32 1.1.2.2 yamt 33 1.1.2.2 yamt #include <sys/cdefs.h> 34 1.1.2.2 yamt __KERNEL_RCSID(0, "$NetBSD: kern_cfglock.c,v 1.1.2.2 2010/10/09 03:32:30 yamt Exp $"); 35 1.1.2.2 yamt 36 1.1.2.2 yamt #include <sys/param.h> 37 1.1.2.2 yamt #include <sys/cpu.h> 38 1.1.2.2 yamt #include <sys/mutex.h> 39 1.1.2.2 yamt #include <sys/lwp.h> 40 1.1.2.2 yamt #include <sys/systm.h> 41 1.1.2.2 yamt 42 1.1.2.2 yamt static kmutex_t kernconfig_mutex; 43 1.1.2.2 yamt static lwp_t *kernconfig_lwp; 44 1.1.2.2 yamt static int kernconfig_recurse; 45 1.1.2.2 yamt 46 1.1.2.2 yamt /* 47 1.1.2.2 yamt * Functions for manipulating the kernel configuration lock. This 48 1.1.2.2 yamt * recursive lock should be used to protect all additions and removals 49 1.1.2.2 yamt * of kernel functionality, such as device configuration and loading 50 1.1.2.2 yamt * of modular kernel components. 51 1.1.2.2 yamt */ 52 1.1.2.2 yamt 53 1.1.2.2 yamt void 54 1.1.2.2 yamt kernconfig_lock_init(void) 55 1.1.2.2 yamt { 56 1.1.2.2 yamt 57 1.1.2.2 yamt mutex_init(&kernconfig_mutex, MUTEX_DEFAULT, IPL_NONE); 58 1.1.2.2 yamt kernconfig_lwp = NULL; 59 1.1.2.2 yamt kernconfig_recurse = 0; 60 1.1.2.2 yamt } 61 1.1.2.2 yamt 62 1.1.2.2 yamt void 63 1.1.2.2 yamt kernconfig_lock(void) 64 1.1.2.2 yamt { 65 1.1.2.2 yamt lwp_t *my_lwp; 66 1.1.2.2 yamt 67 1.1.2.2 yamt /* 68 1.1.2.2 yamt * It's OK to check this unlocked, since it could only be set to 69 1.1.2.2 yamt * curlwp by the current thread itself, and not by an interrupt 70 1.1.2.2 yamt * or any other LWP. 71 1.1.2.2 yamt */ 72 1.1.2.2 yamt KASSERT(!cpu_intr_p()); 73 1.1.2.2 yamt my_lwp = curlwp; 74 1.1.2.2 yamt if (kernconfig_lwp == my_lwp) { 75 1.1.2.2 yamt kernconfig_recurse++; 76 1.1.2.2 yamt KASSERT(kernconfig_recurse > 1); 77 1.1.2.2 yamt } else { 78 1.1.2.2 yamt mutex_enter(&kernconfig_mutex); 79 1.1.2.2 yamt kernconfig_lwp = my_lwp; 80 1.1.2.2 yamt kernconfig_recurse = 1; 81 1.1.2.2 yamt } 82 1.1.2.2 yamt } 83 1.1.2.2 yamt 84 1.1.2.2 yamt void 85 1.1.2.2 yamt kernconfig_unlock(void) 86 1.1.2.2 yamt { 87 1.1.2.2 yamt 88 1.1.2.2 yamt KASSERT(kernconfig_is_held()); 89 1.1.2.2 yamt KASSERT(kernconfig_recurse != 0); 90 1.1.2.2 yamt if (--kernconfig_recurse == 0) { 91 1.1.2.2 yamt kernconfig_lwp = NULL; 92 1.1.2.2 yamt mutex_exit(&kernconfig_mutex); 93 1.1.2.2 yamt } 94 1.1.2.2 yamt } 95 1.1.2.2 yamt 96 1.1.2.2 yamt bool 97 1.1.2.2 yamt kernconfig_is_held(void) 98 1.1.2.2 yamt { 99 1.1.2.2 yamt 100 1.1.2.2 yamt return mutex_owned(&kernconfig_mutex); 101 1.1.2.2 yamt } 102
Indexes created Tue Sep 30 20:09:53 GMT 2025