lib/libc_r/uthread/uthread_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  * $FreeBSD: src/lib/libc_r/uthread/uthread_spinlock.c,v 1.8.2.2 2002/10/17 19:37:39 fjoe Exp $
  33  */
  34
  35 extern unsigned int     __sleep(unsigned int);
  36
  37 #include "namespace.h"
  38 #include <stdlib.h>
  39 #include <sys/fcntl.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <sys/sched.h>
  43 #include <pthread.h>
  44 #include <unistd.h>
  45 #include "un-namespace.h"
  46
  47 #include "libc_private.h"
  48 #include "pthread_private.h"
  49
  50 void
  51 _spinunlock(spinlock_t *lck)
  52 {
  53         lck->access_lock = 0;
  54 }
  55
  56 /*
  57  * Lock a location for the running thread. Yield to allow other
  58  * threads to run if this thread is blocked because the lock is
  59  * not available. Note that this function does not sleep. It
  60  * assumes that the lock will be available very soon.
  61  */
  62 void
  63 _spinlock(spinlock_t *lck)
  64 {
  65         struct pthread  *curthread = _get_curthread();
  66
  67         /*
  68          * Try to grab the lock and loop if another thread grabs
  69          * it before we do.
  70          */
  71         while(_atomic_lock(&lck->access_lock)) {
  72                 /* Block the thread until the lock. */
  73                 curthread->data.spinlock = lck;
  74                 _thread_kern_sched_state(PS_SPINBLOCK, __FILE__, __LINE__);
  75         }
  76
  77         /* The running thread now owns the lock: */
  78         lck->lock_owner = (long) curthread;
  79 }
  80
  81 /*
  82  * Lock a location for the running thread. Yield to allow other
  83  * threads to run if this thread is blocked because the lock is
  84  * not available. Note that this function does not sleep. It
  85  * assumes that the lock will be available very soon.
  86  *
  87  * This function checks if the running thread has already locked the
  88  * location, warns if this occurs and creates a thread dump before
  89  * returning.
  90  */
  91 void
  92 _spinlock_debug(spinlock_t *lck, char *fname, int lineno)
  93 {
  94         struct pthread  *curthread = _get_curthread();
  95         int cnt = 0;
  96
  97         /*
  98          * Try to grab the lock and loop if another thread grabs
  99          * it before we do.
 100          */
 101         while(_atomic_lock(&lck->access_lock)) {
 102                 cnt++;
 103                 if (cnt > 100) {
 104                         char str[256];
 105                         snprintf(str, sizeof(str), "%s - Warning: Thread %p attempted to lock %p from %s (%d) was left locked from %s (%d)\n", _getprogname(), curthread, lck, fname, lineno, lck->fname, lck->lineno);
 106                         __sys_extpwrite(2, str, strlen(str), O_FBLOCKING, -1);
 107                         __sleep(1);
 108                         cnt = 0;
 109                 }
 110
 111                 /* Block the thread until the lock. */
 112                 curthread->data.spinlock = lck;
 113                 _thread_kern_sched_state(PS_SPINBLOCK, fname, lineno);
 114         }
 115
 116         /* The running thread now owns the lock: */
 117         lck->lock_owner = (long) curthread;
 118         lck->fname = fname;
 119         lck->lineno = lineno;
 120 }