lib/libpthread/pthread_spin.c

   1 /*      $NetBSD: pthread_spin.c,v 1.4 2008/01/05 01:37:35 ad Exp $      */
   2
   3 /*-
   4  * Copyright (c) 2001, 2006, 2007 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Nathan J. Williams and Andrew Doran.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * Public (POSIX-specified) spinlocks.
  34  */
  35
  36 #include <sys/cdefs.h>
  37 __RCSID("$NetBSD: pthread_spin.c,v 1.4 2008/01/05 01:37:35 ad Exp $");
  38
  39 #include <sys/types.h>
  40 #include <sys/ras.h>
  41
  42 #include <machine/lock.h>
  43
  44 #include <errno.h>
  45 #include <unistd.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48
  49 #include "pthread.h"
  50 #include "pthread_int.h"
  51
  52 int
  53 pthread_spin_init(pthread_spinlock_t *lock, int pshared)
  54 {
  55
  56 #ifdef ERRORCHECK
  57         if (lock == NULL || (pshared != PTHREAD_PROCESS_PRIVATE &&
  58             pshared != PTHREAD_PROCESS_SHARED))
  59                 return EINVAL;
  60 #endif
  61         lock->pts_magic = _PT_SPINLOCK_MAGIC;
  62
  63         /*
  64          * We don't actually use the pshared flag for anything;
  65          * CPU simple locks have all the process-shared properties
  66          * that we want anyway.
  67          */
  68         lock->pts_flags = pshared;
  69         pthread_lockinit(&lock->pts_spin);
  70
  71         return 0;
  72 }
  73
  74 int
  75 pthread_spin_destroy(pthread_spinlock_t *lock)
  76 {
  77
  78 #ifdef ERRORCHECK
  79         if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
  80                 return EINVAL;
  81         if (!__SIMPLELOCK_UNLOCKED_P(&lock->pts_spin))
  82                 return EBUSY;
  83 #endif
  84
  85         lock->pts_magic = _PT_SPINLOCK_DEAD;
  86
  87         return 0;
  88 }
  89
  90 int
  91 pthread_spin_lock(pthread_spinlock_t *lock)
  92 {
  93         pthread_t self;
  94
  95 #ifdef ERRORCHECK
  96         if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
  97                 return EINVAL;
  98 #endif
  99
 100         self = pthread__self();
 101         while (pthread__spintrylock(self, &lock->pts_spin) == 0) {
 102                 pthread__smt_pause();
 103         }
 104
 105         return 0;
 106 }
 107
 108 int
 109 pthread_spin_trylock(pthread_spinlock_t *lock)
 110 {
 111         pthread_t self;
 112
 113 #ifdef ERRORCHECK
 114         if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
 115                 return EINVAL;
 116 #endif
 117
 118         self = pthread__self();
 119         if (pthread__spintrylock(self, &lock->pts_spin) == 0)
 120                 return EBUSY;
 121         return 0;
 122 }
 123
 124 int
 125 pthread_spin_unlock(pthread_spinlock_t *lock)
 126 {
 127         pthread_t self;
 128
 129 #ifdef ERRORCHECK
 130         if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC)
 131                 return EINVAL;
 132 #endif
 133
 134         self = pthread__self();
 135         pthread__spinunlock(self, &lock->pts_spin);
 136
 137         return 0;
 138 }