1 /* $OpenBSD: kern_lock.c,v 1.47 2016/06/19 11:54:33 natano Exp $ */ 2 3 /* 4 * Copyright (c) 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code contains ideas from software contributed to Berkeley by 8 * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating 9 * System project at Carnegie-Mellon University. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 36 */ 37 38 #include <sys/param.h> 39 #include <sys/lock.h> 40 #include <sys/systm.h> 41 #include <sys/sched.h> 42 43 #ifdef MP_LOCKDEBUG 44 /* CPU-dependent timing, this needs to be settable from ddb. */ 45 int __mp_lock_spinout = 200000000; 46 #endif 47 48 #if defined(MULTIPROCESSOR) 49 /* 50 * Functions for manipulating the kernel_lock. We put them here 51 * so that they show up in profiles. 52 */ 53 54 struct __mp_lock kernel_lock; 55 56 void 57 _kernel_lock_init(void) 58 { 59 __mp_lock_init(&kernel_lock); 60 } 61 62 /* 63 * Acquire/release the kernel lock. Intended for use in the scheduler 64 * and the lower half of the kernel. 65 */ 66 67 void 68 _kernel_lock(void) 69 { 70 SCHED_ASSERT_UNLOCKED(); 71 __mp_lock(&kernel_lock); 72 } 73 74 void 75 _kernel_unlock(void) 76 { 77 __mp_unlock(&kernel_lock); 78 } 79 80 int 81 _kernel_lock_held(void) 82 { 83 return (__mp_lock_held(&kernel_lock)); 84 } 85 #endif /* MULTIPROCESSOR */ 86