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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by John Birrell.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD$
  33  *
  34  */
  35
  36 #include <sys/types.h>
  37 #include <machine/atomic.h>
  38
  39 #include <libc_private.h>
  40 #include "spinlock.h"
  41 #include "thr_private.h"
  42
  43 #define MAX_SPINLOCKS   72
  44
  45 struct spinlock_extra {
  46         spinlock_t      *owner;
  47         pthread_mutex_t lock;
  48 };
  49
  50 static void     init_spinlock(spinlock_t *lck);
  51
  52 static struct pthread_mutex_attr static_mutex_attr =
  53     PTHREAD_MUTEXATTR_STATIC_INITIALIZER;
  54 static pthread_mutexattr_t      static_mattr = &static_mutex_attr;
  55
  56 static pthread_mutex_t          spinlock_static_lock;
  57 static struct spinlock_extra    extra[MAX_SPINLOCKS];
  58 static int                      spinlock_count = 0;
  59 static int                      initialized = 0;
  60
  61 LT10_COMPAT_PRIVATE(_spinlock);
  62 LT10_COMPAT_PRIVATE(_spinlock_debug);
  63 LT10_COMPAT_PRIVATE(_spinunlock);
  64
  65 /*
  66  * These are for compatability only.  Spinlocks of this type
  67  * are deprecated.
  68  */
  69
  70 void
  71 _spinunlock(spinlock_t *lck)
  72 {
  73         struct spinlock_extra *extra;
  74
  75         extra = (struct spinlock_extra *)lck->fname;
  76         _pthread_mutex_unlock(&extra->lock);
  77 }
  78
  79 /*
  80  * Lock a location for the running thread. Yield to allow other
  81  * threads to run if this thread is blocked because the lock is
  82  * not available. Note that this function does not sleep. It
  83  * assumes that the lock will be available very soon.
  84  */
  85 void
  86 _spinlock(spinlock_t *lck)
  87 {
  88         struct spinlock_extra *extra;
  89
  90         if (!__isthreaded)
  91                 PANIC("Spinlock called when not threaded.");
  92         if (!initialized)
  93                 PANIC("Spinlocks not initialized.");
  94         /*
  95          * Try to grab the lock and loop if another thread grabs
  96          * it before we do.
  97          */
  98         if (lck->fname == NULL)
  99                 init_spinlock(lck);
 100         extra = (struct spinlock_extra *)lck->fname;
 101         _pthread_mutex_lock(&extra->lock);
 102 }
 103
 104 /*
 105  * Lock a location for the running thread. Yield to allow other
 106  * threads to run if this thread is blocked because the lock is
 107  * not available. Note that this function does not sleep. It
 108  * assumes that the lock will be available very soon.
 109  *
 110  * This function checks if the running thread has already locked the
 111  * location, warns if this occurs and creates a thread dump before
 112  * returning.
 113  */
 114 void
 115 _spinlock_debug(spinlock_t *lck, char *fname, int lineno)
 116 {
 117         _spinlock(lck);
 118 }
 119
 120 static void
 121 init_spinlock(spinlock_t *lck)
 122 {
 123         _pthread_mutex_lock(&spinlock_static_lock);
 124         if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
 125                 lck->fname = (char *)&extra[spinlock_count];
 126                 extra[spinlock_count].owner = lck;
 127                 spinlock_count++;
 128         }
 129         _pthread_mutex_unlock(&spinlock_static_lock);
 130         if (lck->fname == NULL)
 131                 PANIC("Exceeded max spinlocks");
 132 }
 133
 134 void
 135 _thr_spinlock_init(void)
 136 {
 137         int i;
 138
 139         if (initialized != 0) {
 140                 _thr_mutex_reinit(&spinlock_static_lock);
 141                 for (i = 0; i < spinlock_count; i++)
 142                         _thr_mutex_reinit(&extra[i].lock);
 143         } else {
 144                 if (_pthread_mutex_init(&spinlock_static_lock, &static_mattr))
 145                         PANIC("Cannot initialize spinlock_static_lock");
 146                 for (i = 0; i < MAX_SPINLOCKS; i++) {
 147                         if (_pthread_mutex_init(&extra[i].lock, &static_mattr))
 148                                 PANIC("Cannot initialize spinlock extra");
 149                 }
 150                 initialized = 1;
 151         }
 152 }