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