1 /*- 2 * Copyright (c) 2003 David Xu <davidxu@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/lib/libpthread/thread/thr_pspinlock.c,v 1.2 2003/11/04 19:56:12 deischen Exp $ 27 * $DragonFly: src/lib/libthread_xu/thread/thr_pspinlock.c,v 1.1 2005/02/01 12:38:27 davidxu Exp $ 28 */ 29 30 #include <errno.h> 31 #include <stdlib.h> 32 #include <pthread.h> 33 #include "thr_private.h" 34 35 #define SPIN_COUNT 100000 36 37 __weak_reference(_pthread_spin_init, pthread_spin_init); 38 __weak_reference(_pthread_spin_destroy, pthread_spin_destroy); 39 __weak_reference(_pthread_spin_trylock, pthread_spin_trylock); 40 __weak_reference(_pthread_spin_lock, pthread_spin_lock); 41 __weak_reference(_pthread_spin_unlock, pthread_spin_unlock); 42 43 int 44 _pthread_spin_init(pthread_spinlock_t *lock, int pshared) 45 { 46 struct pthread_spinlock *lck; 47 int ret; 48 49 if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE) 50 ret = EINVAL; 51 else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL) 52 ret = ENOMEM; 53 else { 54 _thr_umtx_init(&lck->s_lock); 55 *lock = lck; 56 ret = 0; 57 } 58 59 return (ret); 60 } 61 62 int 63 _pthread_spin_destroy(pthread_spinlock_t *lock) 64 { 65 int ret; 66 67 if (lock == NULL || *lock == NULL) 68 ret = EINVAL; 69 else { 70 free(*lock); 71 *lock = NULL; 72 ret = 0; 73 } 74 75 return (ret); 76 } 77 78 int 79 _pthread_spin_trylock(pthread_spinlock_t *lock) 80 { 81 struct pthread *curthread = _get_curthread(); 82 struct pthread_spinlock *lck; 83 int ret; 84 85 if (lock == NULL || (lck = *lock) == NULL) 86 ret = EINVAL; 87 else 88 ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock); 89 return (ret); 90 } 91 92 int 93 _pthread_spin_lock(pthread_spinlock_t *lock) 94 { 95 struct pthread *curthread = _get_curthread(); 96 struct pthread_spinlock *lck; 97 int ret, count; 98 99 if (lock == NULL || (lck = *lock) == NULL) 100 ret = EINVAL; 101 else { 102 count = SPIN_COUNT; 103 while ((ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock)) != 0) { 104 while (lck->s_lock) { 105 #ifdef __i386__ 106 /* tell cpu we are spinning */ 107 __asm __volatile("pause"); 108 #endif 109 if (--count <= 0) { 110 count = SPIN_COUNT; 111 _pthread_yield(); 112 } 113 } 114 } 115 ret = 0; 116 } 117 118 return (ret); 119 } 120 121 int 122 _pthread_spin_unlock(pthread_spinlock_t *lock) 123 { 124 struct pthread *curthread = _get_curthread(); 125 struct pthread_spinlock *lck; 126 int ret; 127 128 if (lock == NULL || (lck = *lock) == NULL) 129 ret = EINVAL; 130 else { 131 ret = THR_UMTX_UNLOCK(curthread, &lck->s_lock); 132 } 133 return (ret); 134 } 135