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  * $DragonFly: src/lib/libthread_xu/thread/thr_pspinlock.c,v 1.4 2006/04/06 13:03:09 davidxu Exp $
  27  */
  28
  29 #include "namespace.h"
  30 #include <machine/tls.h>
  31
  32 #include <errno.h>
  33 #include <stdlib.h>
  34 #include <pthread.h>
  35 #include <pthread_np.h>
  36 #include "un-namespace.h"
  37
  38 #include "thr_private.h"
  39
  40 #define SPIN_COUNT 100000
  41
  42 int
  43 _pthread_spin_init(pthread_spinlock_t *lock, int pshared)
  44 {
  45         struct pthread_spinlock *lck;
  46         int ret;
  47
  48         if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
  49                 ret = EINVAL;
  50         else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
  51                 ret = ENOMEM;
  52         else {
  53                 _thr_umtx_init(&lck->s_lock);
  54                 *lock = lck;
  55                 ret = 0;
  56         }
  57
  58         return (ret);
  59 }
  60
  61 int
  62 _pthread_spin_destroy(pthread_spinlock_t *lock)
  63 {
  64         int ret;
  65
  66         if (lock == NULL || *lock == NULL)
  67                 ret = EINVAL;
  68         else {
  69                 free(*lock);
  70                 *lock = NULL;
  71                 ret = 0;
  72         }
  73
  74         return (ret);
  75 }
  76
  77 int
  78 _pthread_spin_trylock(pthread_spinlock_t *lock)
  79 {
  80         struct pthread *curthread = tls_get_curthread();
  81         struct pthread_spinlock *lck;
  82         int ret;
  83
  84         if (lock == NULL || (lck = *lock) == NULL)
  85                 ret = EINVAL;
  86         else
  87                 ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock);
  88         return (ret);
  89 }
  90
  91 int
  92 _pthread_spin_lock(pthread_spinlock_t *lock)
  93 {
  94         struct pthread *curthread = tls_get_curthread();
  95         struct pthread_spinlock *lck;
  96         int ret, count;
  97
  98         if (lock == NULL || (lck = *lock) == NULL)
  99                 ret = EINVAL;
 100         else {
 101                 count = SPIN_COUNT;
 102                 while ((ret = THR_UMTX_TRYLOCK(curthread, &lck->s_lock)) != 0) {
 103                         while (lck->s_lock) {
 104 #ifdef __i386__
 105                                 /* tell cpu we are spinning */
 106                                 __asm __volatile("pause");
 107 #endif
 108                                 if (--count <= 0) {
 109                                         count = SPIN_COUNT;
 110                                         _pthread_yield();
 111                                 }
 112                         }
 113                 }
 114                 ret = 0;
 115         }
 116
 117         return (ret);
 118 }
 119
 120 int
 121 _pthread_spin_unlock(pthread_spinlock_t *lock)
 122 {
 123         struct pthread *curthread = tls_get_curthread();
 124         struct pthread_spinlock *lck;
 125         int ret;
 126
 127         if (lock == NULL || (lck = *lock) == NULL)
 128                 ret = EINVAL;
 129         else {
 130                 THR_UMTX_UNLOCK(curthread, &lck->s_lock);
 131                 ret = 0;
 132         }
 133         return (ret);
 134 }
 135
 136 __strong_reference(_pthread_spin_init, pthread_spin_init);
 137 __strong_reference(_pthread_spin_destroy, pthread_spin_destroy);
 138 __strong_reference(_pthread_spin_trylock, pthread_spin_trylock);
 139 __strong_reference(_pthread_spin_lock, pthread_spin_lock);
 140 __strong_reference(_pthread_spin_unlock, pthread_spin_unlock);
 141