lib/libthread_xu/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  * $DragonFly: src/lib/libthread_xu/thread/thr_spinlock.c,v 1.3 2006/04/06 13:03:09 davidxu Exp $
  30  */
  31
  32 #include "namespace.h"
  33 #include <sys/types.h>
  34 #include <machine/atomic.h>
  35 #include <machine/tls.h>
  36 #include <pthread.h>
  37 #include <libc_private.h>
  38 #include "spinlock.h"
  39 #include "un-namespace.h"
  40
  41 #include "thr_private.h"
  42
  43 #define MAX_SPINLOCKS   256
  44
  45 /*
  46  * These data structures are used to trace all spinlocks
  47  * in libc.
  48  */
  49 struct spinlock_extra {
  50         spinlock_t      *owner;
  51 };
  52
  53 static umtx_t                   spinlock_static_lock;
  54 static struct spinlock_extra    extra[MAX_SPINLOCKS];
  55 static int                      spinlock_count;
  56 static int                      initialized;
  57
  58 static void     init_spinlock(spinlock_t *lck);
  59
  60 /*
  61  * These are for compatability only.  Spinlocks of this type
  62  * are deprecated.
  63  */
  64
  65 void
  66 _spinunlock(spinlock_t *lck)
  67 {
  68         struct pthread *curthread = tls_get_curthread();
  69
  70         THR_UMTX_UNLOCK(curthread, (volatile umtx_t *)&lck->access_lock);
  71 }
  72
  73 void
  74 _spinlock(spinlock_t *lck)
  75 {
  76         struct pthread *curthread;
  77
  78         if (!__isthreaded)
  79                 PANIC("Spinlock called when not threaded.");
  80         if (!initialized)
  81                 PANIC("Spinlocks not initialized.");
  82         if (lck->fname == NULL)
  83                 init_spinlock(lck);
  84
  85         curthread = tls_get_curthread();
  86         THR_UMTX_LOCK(curthread, (volatile umtx_t *)&lck->access_lock);
  87 }
  88
  89 /*
  90  * Returns 0 on success, else EBUSY
  91  */
  92 int
  93 _spintrylock(spinlock_t *lck)
  94 {
  95         struct pthread *curthread;
  96
  97         if (!__isthreaded)
  98                 PANIC("Spinlock called when not threaded.");
  99         if (!initialized)
 100                 PANIC("Spinlocks not initialized.");
 101         if (lck->fname == NULL)
 102                 init_spinlock(lck);
 103
 104         curthread = tls_get_curthread();
 105         return(THR_UMTX_TRYLOCK(curthread,
 106                                 (volatile umtx_t *)&lck->access_lock));
 107 }
 108
 109 void
 110 _spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused)
 111 {
 112         _spinlock(lck);
 113 }
 114
 115 static void
 116 init_spinlock(spinlock_t *lck)
 117 {
 118         static int count = 0;
 119         struct pthread *curthread = tls_get_curthread();
 120
 121         THR_UMTX_LOCK(curthread, &spinlock_static_lock);
 122         if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
 123                 lck->fname = (char *)&extra[spinlock_count];
 124                 extra[spinlock_count].owner = lck;
 125                 spinlock_count++;
 126         }
 127         THR_UMTX_UNLOCK(curthread, &spinlock_static_lock);
 128         if (lck->fname == NULL && ++count < 5)
 129                 stderr_debug("Warning: exceeded max spinlocks");
 130 }
 131
 132 void
 133 _thr_spinlock_init(void)
 134 {
 135         int i;
 136
 137         _thr_umtx_init(&spinlock_static_lock);
 138         if (initialized != 0) {
 139                 /*
 140                  * called after fork() to reset state of libc spin locks,
 141                  * it is not quite right since libc may be in inconsistent
 142                  * state, resetting the locks to allow current thread to be
 143                  * able to hold them may not help things too much, but
 144                  * anyway, we do our best.
 145                  * it is better to do pthread_atfork in libc.
 146                  */
 147                 for (i = 0; i < spinlock_count; i++)
 148                         _thr_umtx_init((volatile umtx_t *)
 149                                 &extra[i].owner->access_lock);
 150         } else {
 151                 initialized = 1;
 152         }
 153 }