lib/libkse/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 <sys/types.h>
  30 #include <errno.h>
  31 #include <pthread.h>
  32 #include <stdint.h>
  33 #include <stdlib.h>
  34
  35 #include "atomic_ops.h"
  36 #include "thr_private.h"
  37
  38 #define SPIN_COUNT 10000
  39
  40 LT10_COMPAT_PRIVATE(_pthread_spin_init);
  41 LT10_COMPAT_DEFAULT(pthread_spin_init);
  42 LT10_COMPAT_PRIVATE(_pthread_spin_destroy);
  43 LT10_COMPAT_DEFAULT(pthread_spin_destroy);
  44 LT10_COMPAT_PRIVATE(_pthread_spin_trylock);
  45 LT10_COMPAT_DEFAULT(pthread_spin_trylock);
  46 LT10_COMPAT_PRIVATE(_pthread_spin_lock);
  47 LT10_COMPAT_DEFAULT(pthread_spin_lock);
  48 LT10_COMPAT_PRIVATE(_pthread_spin_unlock);
  49 LT10_COMPAT_DEFAULT(pthread_spin_unlock);
  50
  51 __weak_reference(_pthread_spin_init, pthread_spin_init);
  52 __weak_reference(_pthread_spin_destroy, pthread_spin_destroy);
  53 __weak_reference(_pthread_spin_trylock, pthread_spin_trylock);
  54 __weak_reference(_pthread_spin_lock, pthread_spin_lock);
  55 __weak_reference(_pthread_spin_unlock, pthread_spin_unlock);
  56
  57 int
  58 _pthread_spin_init(pthread_spinlock_t *lock, int pshared)
  59 {
  60         struct pthread_spinlock *lck;
  61         int ret;
  62
  63         if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
  64                 ret = EINVAL;
  65         else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
  66                 ret = ENOMEM;
  67         else {
  68                 lck->s_lock = 0;
  69                 lck->s_owner= NULL;
  70                 *lock = lck;
  71                 ret = 0;
  72         }
  73
  74         return (ret);
  75 }
  76
  77 int
  78 _pthread_spin_destroy(pthread_spinlock_t *lock)
  79 {
  80         int ret;
  81
  82         if (lock == NULL || *lock == NULL)
  83                 ret = EINVAL;
  84         else if ((*lock)->s_owner != NULL)
  85                 ret = EBUSY;
  86         else {
  87                 free(*lock);
  88                 *lock = NULL;
  89                 ret = 0;
  90         }
  91
  92         return (ret);
  93 }
  94
  95 int
  96 _pthread_spin_trylock(pthread_spinlock_t *lock)
  97 {
  98         struct pthread_spinlock *lck;
  99         struct pthread *self = _pthread_self();
 100         int oldval, ret;
 101
 102         if (lock == NULL || (lck = *lock) == NULL)
 103                 ret = EINVAL;
 104         else if (lck->s_owner == self)
 105                 ret = EDEADLK;
 106         else if (lck->s_lock != 0)
 107                 ret = EBUSY;
 108         else {
 109                 atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
 110                 if (oldval)
 111                         ret = EBUSY;
 112                 else {
 113                         lck->s_owner = _pthread_self();
 114                         ret = 0;
 115                 }
 116         }
 117         return (ret);
 118 }
 119
 120 int
 121 _pthread_spin_lock(pthread_spinlock_t *lock)
 122 {
 123         struct pthread_spinlock *lck;
 124         struct pthread *self = _pthread_self();
 125         int count, oldval, ret;
 126
 127         if (lock == NULL || (lck = *lock) == NULL)
 128                 ret = EINVAL;
 129         else if (lck->s_owner == self)
 130                 ret = EDEADLK;
 131         else {
 132                 do {
 133                         count = SPIN_COUNT;
 134                         while (lck->s_lock) {
 135 #ifdef __i386__
 136                                 /* tell cpu we are spinning */
 137                                 __asm __volatile("pause");
 138 #endif
 139                                 if (--count <= 0) {
 140                                         count = SPIN_COUNT;
 141                                         _pthread_yield();
 142                                 }
 143                         }
 144                         atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
 145                 } while (oldval);
 146
 147                 lck->s_owner = self;
 148                 ret = 0;
 149         }
 150
 151         return (ret);
 152 }
 153
 154 int
 155 _pthread_spin_unlock(pthread_spinlock_t *lock)
 156 {
 157         struct pthread_spinlock *lck;
 158         int ret;
 159
 160         if (lock == NULL || (lck = *lock) == NULL)
 161                 ret = EINVAL;
 162         else {
 163                 if (lck->s_owner != _pthread_self())
 164                         ret = EPERM;
 165                 else {
 166                         lck->s_owner = NULL;
 167                         atomic_swap_int((int *)&lck->s_lock, 0, &ret);
 168                         ret = 0;
 169                 }
 170         }
 171
 172         return (ret);
 173 }
 174