lib/libthread_xu/thread/thr_pspinlock.c

   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 }