1 /* $OpenBSD: kern_lock.c,v 1.48 2017/04/20 13:20:17 visa 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/mplock.h> 41 #include <sys/systm.h> 42 #include <sys/sched.h> 43 #include <sys/witness.h> 44 #include <sys/_lock.h> 45 46 #ifdef MP_LOCKDEBUG 47 /* CPU-dependent timing, this needs to be settable from ddb. */ 48 int __mp_lock_spinout = 200000000; 49 #endif 50 51 #if defined(MULTIPROCESSOR) 52 /* 53 * Functions for manipulating the kernel_lock. We put them here 54 * so that they show up in profiles. 55 */ 56 57 struct __mp_lock kernel_lock; 58 59 void 60 _kernel_lock_init(void) 61 { 62 __mp_lock_init(&kernel_lock); 63 } 64 65 /* 66 * Acquire/release the kernel lock. Intended for use in the scheduler 67 * and the lower half of the kernel. 68 */ 69 70 void 71 _kernel_lock(const char *file, int line) 72 { 73 SCHED_ASSERT_UNLOCKED(); 74 #ifdef WITNESS 75 ___mp_lock(&kernel_lock, file, line); 76 #else 77 __mp_lock(&kernel_lock); 78 #endif 79 } 80 81 void 82 _kernel_unlock(void) 83 { 84 __mp_unlock(&kernel_lock); 85 } 86 87 int 88 _kernel_lock_held(void) 89 { 90 return (__mp_lock_held(&kernel_lock)); 91 } 92 93 #ifdef WITNESS 94 void 95 _mp_lock_init(struct __mp_lock *mpl, struct lock_type *type) 96 { 97 mpl->mpl_lock_obj.lo_name = type->lt_name; 98 mpl->mpl_lock_obj.lo_type = type; 99 if (mpl == &kernel_lock) 100 mpl->mpl_lock_obj.lo_flags = LO_WITNESS | LO_INITIALIZED | 101 LO_SLEEPABLE | (LO_CLASS_KERNEL_LOCK << LO_CLASSSHIFT); 102 else if (mpl == &sched_lock) 103 mpl->mpl_lock_obj.lo_flags = LO_WITNESS | LO_INITIALIZED | 104 LO_RECURSABLE | (LO_CLASS_SCHED_LOCK << LO_CLASSSHIFT); 105 WITNESS_INIT(&mpl->mpl_lock_obj, type); 106 107 ___mp_lock_init(mpl); 108 } 109 #endif /* WITNESS */ 110 111 #endif /* MULTIPROCESSOR */ 112