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