lib/libthr/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  * $FreeBSD$
  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
  45 int
  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_umutex_init(&lck->s_lock);
  57                 *lock = lck;
  58                 ret = 0;
  59         }
  60
  61         return (ret);
  62 }
  63
  64 int
  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
  80 int
  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_UMUTEX_TRYLOCK(curthread, &lck->s_lock);
  91         return (ret);
  92 }
  93
  94 int
  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_UMUTEX_TRYLOCK(curthread, &lck->s_lock)) != 0) {
 106                         while (lck->s_lock.m_owner) {
 107                                 if (!_thr_is_smp) {
 108                                         _pthread_yield();
 109                                 } else {
 110                                         CPU_SPINWAIT;
 111
 112                                         if (--count <= 0) {
 113                                                 count = SPIN_COUNT;
 114                                                 _pthread_yield();
 115                                         }
 116                                 }
 117                         }
 118                 }
 119                 ret = 0;
 120         }
 121
 122         return (ret);
 123 }
 124
 125 int
 126 _pthread_spin_unlock(pthread_spinlock_t *lock)
 127 {
 128         struct pthread *curthread = _get_curthread();
 129         struct pthread_spinlock *lck;
 130         int ret;
 131
 132         if (lock == NULL || (lck = *lock) == NULL)
 133                 ret = EINVAL;
 134         else {
 135                 ret = THR_UMUTEX_UNLOCK(curthread, &lck->s_lock);
 136         }
 137         return (ret);
 138 }