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 "namespace.h"
  34 #include <sys/types.h>
  35 #include <machine/atomic.h>
  36 #include <pthread.h>
  37 #include <libc_private.h>
  38 #include "un-namespace.h"
  39 #include "spinlock.h"
  40 #include "thr_private.h"
  41
  42 #define MAX_SPINLOCKS   72
  43
  44 struct spinlock_extra {
  45         spinlock_t      *owner;
  46         pthread_mutex_t lock;
  47 };
  48
  49 struct nv_spinlock {
  50         long   access_lock;
  51         long   lock_owner;
  52         struct spinlock_extra *extra;   /* overlays fname in spinlock_t */
  53         int    lineno;
  54 };
  55 typedef struct nv_spinlock nv_spinlock_t;
  56
  57 static void     init_spinlock(spinlock_t *lck);
  58
  59 static struct pthread_mutex_attr static_mutex_attr =
  60     PTHREAD_MUTEXATTR_STATIC_INITIALIZER;
  61 static pthread_mutexattr_t      static_mattr = &static_mutex_attr;
  62
  63 static pthread_mutex_t          spinlock_static_lock;
  64 static struct spinlock_extra    extra[MAX_SPINLOCKS];
  65 static int                      spinlock_count = 0;
  66 static int                      initialized = 0;
  67
  68 /*
  69  * These are for compatability only.  Spinlocks of this type
  70  * are deprecated.
  71  */
  72
  73 void
  74 _spinunlock(spinlock_t *lck)
  75 {
  76         struct spinlock_extra *sl_extra;
  77
  78         sl_extra = ((nv_spinlock_t *)lck)->extra;
  79         _pthread_mutex_unlock(&sl_extra->lock);
  80 }
  81
  82 /*
  83  * Lock a location for the running thread. Yield to allow other
  84  * threads to run if this thread is blocked because the lock is
  85  * not available. Note that this function does not sleep. It
  86  * assumes that the lock will be available very soon.
  87  */
  88 void
  89 _spinlock(spinlock_t *lck)
  90 {
  91         struct spinlock_extra *sl_extra;
  92
  93         if (!__isthreaded)
  94                 PANIC("Spinlock called when not threaded.");
  95         if (!initialized)
  96                 PANIC("Spinlocks not initialized.");
  97         /*
  98          * Try to grab the lock and loop if another thread grabs
  99          * it before we do.
 100          */
 101         if (lck->fname == NULL)
 102                 init_spinlock(lck);
 103         sl_extra = ((nv_spinlock_t *)lck)->extra;
 104         _pthread_mutex_lock(&sl_extra->lock);
 105 }
 106
 107 /*
 108  * Lock a location for the running thread. Yield to allow other
 109  * threads to run if this thread is blocked because the lock is
 110  * not available. Note that this function does not sleep. It
 111  * assumes that the lock will be available very soon.
 112  *
 113  * This function checks if the running thread has already locked the
 114  * location, warns if this occurs and creates a thread dump before
 115  * returning.
 116  */
 117 void
 118 _spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused)
 119 {
 120         _spinlock(lck);
 121 }
 122
 123 static void
 124 init_spinlock(spinlock_t *lck)
 125 {
 126         _pthread_mutex_lock(&spinlock_static_lock);
 127         if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
 128                 lck->fname = (char *)&extra[spinlock_count];
 129                 extra[spinlock_count].owner = lck;
 130                 spinlock_count++;
 131         }
 132         _pthread_mutex_unlock(&spinlock_static_lock);
 133         if (lck->fname == NULL)
 134                 PANIC("Exceeded max spinlocks");
 135 }
 136
 137 void
 138 _thr_spinlock_init(void)
 139 {
 140         int i;
 141
 142         if (initialized != 0) {
 143                 _thr_mutex_reinit(&spinlock_static_lock);
 144                 for (i = 0; i < spinlock_count; i++)
 145                         _thr_mutex_reinit(&extra[i].lock);
 146         } else {
 147                 if (_pthread_mutex_init(&spinlock_static_lock, &static_mattr))
 148                         PANIC("Cannot initialize spinlock_static_lock");
 149                 for (i = 0; i < MAX_SPINLOCKS; i++) {
 150                         if (_pthread_mutex_init(&extra[i].lock, &static_mattr))
 151                                 PANIC("Cannot initialize spinlock extra");
 152                 }
 153                 initialized = 1;
 154         }
 155 }