lib/libkse/thread/thr_spinlock.c

   1 /*
   2  * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>.
   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  * 3. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD$
  30  *
  31  */
  32
  33 #include <sys/types.h>
  34 #include <machine/atomic.h>
  35
  36 #include <libc_private.h>
  37 #include "spinlock.h"
  38 #include "thr_private.h"
  39
  40 #define MAX_SPINLOCKS   72
  41
  42 struct spinlock_extra {
  43         spinlock_t      *owner;
  44         pthread_mutex_t lock;
  45 };
  46
  47 static void     init_spinlock(spinlock_t *lck);
  48
  49 static struct pthread_mutex_attr static_mutex_attr =
  50     PTHREAD_MUTEXATTR_STATIC_INITIALIZER;
  51 static pthread_mutexattr_t      static_mattr = &static_mutex_attr;
  52
  53 static pthread_mutex_t          spinlock_static_lock;
  54 static struct spinlock_extra    extra[MAX_SPINLOCKS];
  55 static int                      spinlock_count = 0;
  56 static int                      initialized = 0;
  57
  58 LT10_COMPAT_PRIVATE(_spinlock);
  59 LT10_COMPAT_PRIVATE(_spinlock_debug);
  60 LT10_COMPAT_PRIVATE(_spinunlock);
  61
  62 /*
  63  * These are for compatability only.  Spinlocks of this type
  64  * are deprecated.
  65  */
  66
  67 void
  68 _spinunlock(spinlock_t *lck)
  69 {
  70         struct spinlock_extra *extra;
  71
  72         extra = (struct spinlock_extra *)lck->fname;
  73         _pthread_mutex_unlock(&extra->lock);
  74 }
  75
  76 /*
  77  * Lock a location for the running thread. Yield to allow other
  78  * threads to run if this thread is blocked because the lock is
  79  * not available. Note that this function does not sleep. It
  80  * assumes that the lock will be available very soon.
  81  */
  82 void
  83 _spinlock(spinlock_t *lck)
  84 {
  85         struct spinlock_extra *extra;
  86
  87         if (!__isthreaded)
  88                 PANIC("Spinlock called when not threaded.");
  89         if (!initialized)
  90                 PANIC("Spinlocks not initialized.");
  91         /*
  92          * Try to grab the lock and loop if another thread grabs
  93          * it before we do.
  94          */
  95         if (lck->fname == NULL)
  96                 init_spinlock(lck);
  97         extra = (struct spinlock_extra *)lck->fname;
  98         _pthread_mutex_lock(&extra->lock);
  99 }
 100
 101 /*
 102  * Lock a location for the running thread. Yield to allow other
 103  * threads to run if this thread is blocked because the lock is
 104  * not available. Note that this function does not sleep. It
 105  * assumes that the lock will be available very soon.
 106  *
 107  * This function checks if the running thread has already locked the
 108  * location, warns if this occurs and creates a thread dump before
 109  * returning.
 110  */
 111 void
 112 _spinlock_debug(spinlock_t *lck, char *fname, int lineno)
 113 {
 114         _spinlock(lck);
 115 }
 116
 117 static void
 118 init_spinlock(spinlock_t *lck)
 119 {
 120         _pthread_mutex_lock(&spinlock_static_lock);
 121         if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
 122                 lck->fname = (char *)&extra[spinlock_count];
 123                 extra[spinlock_count].owner = lck;
 124                 spinlock_count++;
 125         }
 126         _pthread_mutex_unlock(&spinlock_static_lock);
 127         if (lck->fname == NULL)
 128                 PANIC("Exceeded max spinlocks");
 129 }
 130
 131 void
 132 _thr_spinlock_init(void)
 133 {
 134         int i;
 135
 136         if (initialized != 0) {
 137                 _thr_mutex_reinit(&spinlock_static_lock);
 138                 for (i = 0; i < spinlock_count; i++)
 139                         _thr_mutex_reinit(&extra[i].lock);
 140         } else {
 141                 if (_pthread_mutex_init(&spinlock_static_lock, &static_mattr))
 142                         PANIC("Cannot initialize spinlock_static_lock");
 143                 for (i = 0; i < MAX_SPINLOCKS; i++) {
 144                         if (_pthread_mutex_init(&extra[i].lock, &static_mattr))
 145                                 PANIC("Cannot initialize spinlock extra");
 146                 }
 147                 initialized = 1;
 148         }
 149 }