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. 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  * $DragonFly: src/lib/libthread_xu/thread/thr_spinlock.c,v 1.3 2006/04/06 13:03:09 davidxu Exp $
  33  */
  34
  35 #include "namespace.h"
  36 #include <sys/types.h>
  37 #include <machine/atomic.h>
  38 #include <machine/tls.h>
  39 #include <pthread.h>
  40 #include <libc_private.h>
  41 #include "spinlock.h"
  42 #include "un-namespace.h"
  43
  44 #include "thr_private.h"
  45
  46 #define MAX_SPINLOCKS   128
  47
  48 /*
  49  * These data structures are used to trace all spinlocks
  50  * in libc.
  51  */
  52 struct spinlock_extra {
  53         spinlock_t      *owner;
  54 };
  55
  56 static umtx_t                   spinlock_static_lock;
  57 static struct spinlock_extra    extra[MAX_SPINLOCKS];
  58 static int                      spinlock_count;
  59 static int                      initialized;
  60
  61 static void     init_spinlock(spinlock_t *lck);
  62
  63 /*
  64  * These are for compatability only.  Spinlocks of this type
  65  * are deprecated.
  66  */
  67
  68 void
  69 _spinunlock(spinlock_t *lck)
  70 {
  71         struct pthread *curthread = tls_get_curthread();
  72
  73         THR_UMTX_UNLOCK(curthread, (volatile umtx_t *)&lck->access_lock);
  74 }
  75
  76 void
  77 _spinlock(spinlock_t *lck)
  78 {
  79         struct pthread *curthread;
  80
  81         if (!__isthreaded)
  82                 PANIC("Spinlock called when not threaded.");
  83         if (!initialized)
  84                 PANIC("Spinlocks not initialized.");
  85         if (lck->fname == NULL)
  86                 init_spinlock(lck);
  87
  88         curthread = tls_get_curthread();
  89         THR_UMTX_LOCK(curthread, (volatile umtx_t *)&lck->access_lock);
  90 }
  91
  92 /*
  93  * Returns 0 on success, else EBUSY
  94  */
  95 int
  96 _spintrylock(spinlock_t *lck)
  97 {
  98         struct pthread *curthread;
  99
 100         if (!__isthreaded)
 101                 PANIC("Spinlock called when not threaded.");
 102         if (!initialized)
 103                 PANIC("Spinlocks not initialized.");
 104         if (lck->fname == NULL)
 105                 init_spinlock(lck);
 106
 107         curthread = tls_get_curthread();
 108         return(THR_UMTX_TRYLOCK(curthread,
 109                                 (volatile umtx_t *)&lck->access_lock));
 110 }
 111
 112 void
 113 _spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused)
 114 {
 115         _spinlock(lck);
 116 }
 117
 118 static void
 119 init_spinlock(spinlock_t *lck)
 120 {
 121         static int count = 0;
 122         struct pthread *curthread = tls_get_curthread();
 123
 124         THR_UMTX_LOCK(curthread, &spinlock_static_lock);
 125         if ((lck->fname == NULL) && (spinlock_count < MAX_SPINLOCKS)) {
 126                 lck->fname = (char *)&extra[spinlock_count];
 127                 extra[spinlock_count].owner = lck;
 128                 spinlock_count++;
 129         }
 130         THR_UMTX_UNLOCK(curthread, &spinlock_static_lock);
 131         if (lck->fname == NULL && ++count < 5)
 132                 stderr_debug("Warning: exceeded max spinlocks");
 133 }
 134
 135 void
 136 _thr_spinlock_init(void)
 137 {
 138         int i;
 139
 140         _thr_umtx_init(&spinlock_static_lock);
 141         if (initialized != 0) {
 142                 /*
 143                  * called after fork() to reset state of libc spin locks,
 144                  * it is not quite right since libc may be in inconsistent
 145                  * state, resetting the locks to allow current thread to be
 146                  * able to hold them may not help things too much, but
 147                  * anyway, we do our best.
 148                  * it is better to do pthread_atfork in libc.
 149                  */
 150                 for (i = 0; i < spinlock_count; i++)
 151                         _thr_umtx_init((volatile umtx_t *)
 152                                 &extra[i].owner->access_lock);
 153         } else {
 154                 initialized = 1;
 155         }
 156 }