thr_pspinlock.c revision 161068
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: head/lib/libthr/thread/thr_pspinlock.c 161068 2006-08-08 04:42:41Z davidxu $ 27 */ 28 29#include "namespace.h" 30#include <errno.h> 31#include <stdlib.h> 32#include <pthread.h> 33#include "un-namespace.h" 34 35#include "thr_private.h" 36 37#define SPIN_COUNT 100000 38 39__weak_reference(_pthread_spin_init, pthread_spin_init); 40__weak_reference(_pthread_spin_destroy, pthread_spin_destroy); 41__weak_reference(_pthread_spin_trylock, pthread_spin_trylock); 42__weak_reference(_pthread_spin_lock, pthread_spin_lock); 43__weak_reference(_pthread_spin_unlock, pthread_spin_unlock); 44 45int 46_pthread_spin_init(pthread_spinlock_t *lock, int pshared) 47{ 48 struct pthread_spinlock *lck; 49 int ret; 50 51 if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE) 52 ret = EINVAL; 53 else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL) 54 ret = ENOMEM; 55 else { 56 _thr_umtx_init(&lck->s_lock); 57 *lock = lck; 58 ret = 0; 59 } 60 61 return (ret); 62} 63 64int 65_pthread_spin_destroy(pthread_spinlock_t *lock) 66{ 67 int ret; 68 69 if (lock == NULL || *lock == NULL) 70 ret = EINVAL; 71 else { 72 free(*lock); 73 *lock = NULL; 74 ret = 0; 75 } 76 77 return (ret); 78} 79 80int 81_pthread_spin_trylock(pthread_spinlock_t *lock) 82{ 83 struct pthread *curthread = _get_curthread(); 84 struct pthread_spinlock *lck; 85 int ret; 86 87 if (lock == NULL || (lck = *lock) == NULL) 88 ret = EINVAL; 89 else 90 ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock); 91 return (ret); 92} 93 94int 95_pthread_spin_lock(pthread_spinlock_t *lock) 96{ 97 struct pthread *curthread = _get_curthread(); 98 struct pthread_spinlock *lck; 99 int ret, count; 100 101 if (lock == NULL || (lck = *lock) == NULL) 102 ret = EINVAL; 103 else { 104 count = SPIN_COUNT; 105 while ((ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock)) != 0) { 106 while (lck->s_lock) { 107 if (_thr_smp_cpus <= 1) { 108 _pthread_yield(); 109 } else { 110#if defined(__i386__) || defined(__x86_64__) 111 /* tell cpu we are spinning */ 112 __asm __volatile("pause"); 113#endif 114 if (--count <= 0) { 115 count = SPIN_COUNT; 116 _pthread_yield(); 117 } 118 } 119 } 120 } 121 ret = 0; 122 } 123 124 return (ret); 125} 126 127int 128_pthread_spin_unlock(pthread_spinlock_t *lock) 129{ 130 struct pthread *curthread = _get_curthread(); 131 struct pthread_spinlock *lck; 132 int ret; 133 134 if (lock == NULL || (lck = *lock) == NULL) 135 ret = EINVAL; 136 else { 137 ret = THR_UMTX_UNLOCK(curthread, &lck->s_lock); 138 } 139 return (ret); 140} 141