1 /* $NetBSD: pthread_spin.c,v 1.2 2007/09/10 11:34:06 skrll Exp $ */ 2 3 /*- 4 * Copyright (c) 2001, 2006, 2007 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Nathan J. Williams and Andrew Doran. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * Public (POSIX-specified) spinlocks. 41 */ 42 43 #include <sys/cdefs.h> 44 __RCSID("$NetBSD: pthread_spin.c,v 1.2 2007/09/10 11:34:06 skrll Exp $"); 45 46 #include <sys/types.h> 47 #include <sys/lock.h> 48 #include <sys/ras.h> 49 50 #include <errno.h> 51 #include <unistd.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 55 #include "pthread.h" 56 #include "pthread_int.h" 57 58 int 59 pthread_spin_init(pthread_spinlock_t *lock, int pshared) 60 { 61 62 #ifdef ERRORCHECK 63 if (lock == NULL || (pshared != PTHREAD_PROCESS_PRIVATE && 64 pshared != PTHREAD_PROCESS_SHARED)) 65 return EINVAL; 66 #endif 67 lock->pts_magic = _PT_SPINLOCK_MAGIC; 68 69 /* 70 * We don't actually use the pshared flag for anything; 71 * CPU simple locks have all the process-shared properties 72 * that we want anyway. 73 */ 74 lock->pts_flags = pshared; 75 pthread_lockinit(&lock->pts_spin); 76 77 return 0; 78 } 79 80 int 81 pthread_spin_destroy(pthread_spinlock_t *lock) 82 { 83 84 #ifdef ERRORCHECK 85 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 86 return EINVAL; 87 if (!__SIMPLELOCK_UNLOCKED_P(&lock->pts_spin)) 88 return EBUSY; 89 #endif 90 91 lock->pts_magic = _PT_SPINLOCK_DEAD; 92 93 return 0; 94 } 95 96 int 97 pthread_spin_lock(pthread_spinlock_t *lock) 98 { 99 100 #ifdef ERRORCHECK 101 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 102 return EINVAL; 103 #endif 104 105 while (pthread__simple_lock_try(&lock->pts_spin) == 0) { 106 pthread__smt_pause(); 107 } 108 109 return 0; 110 } 111 112 int 113 pthread_spin_trylock(pthread_spinlock_t *lock) 114 { 115 116 #ifdef ERRORCHECK 117 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 118 return EINVAL; 119 #endif 120 121 if (pthread__simple_lock_try(&lock->pts_spin) == 0) 122 return EBUSY; 123 124 return 0; 125 } 126 127 int 128 pthread_spin_unlock(pthread_spinlock_t *lock) 129 { 130 131 #ifdef ERRORCHECK 132 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 133 return EINVAL; 134 #endif 135 136 pthread__simple_unlock(&lock->pts_spin); 137 138 return 0; 139 } 140