diff options
Diffstat (limited to 'lib/libpthread/thread/thr_spinlock.c')
| -rw-r--r-- | lib/libpthread/thread/thr_spinlock.c | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_spinlock.c b/lib/libpthread/thread/thr_spinlock.c new file mode 100644 index 0000000..9da115e --- /dev/null +++ b/lib/libpthread/thread/thr_spinlock.c @@ -0,0 +1,108 @@ +/* + * Copyright (c) 1997 John Birrell <jb@cimlogic.com.au>. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by John Birrell. + * 4. Neither the name of the author nor the names of any co-contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $Id: uthread_spinlock.c,v 1.3 1998/06/06 07:27:06 jb Exp $ + * + */ + +#include <stdio.h> +#include <sched.h> +#include <unistd.h> +#include <pthread.h> +#include <string.h> +#include "pthread_private.h" + +extern char *__progname; + +/* + * Lock a location for the running thread. Yield to allow other + * threads to run if this thread is blocked because the lock is + * not available. Note that this function does not sleep. It + * assumes that the lock will be available very soon. + */ +void +_spinlock(spinlock_t *lck) +{ + /* + * Try to grab the lock and loop if another thread grabs + * it before we do. + */ + while(_atomic_lock(&lck->access_lock)) { + /* Give up the time slice: */ + sched_yield(); + + /* Check if already locked by the running thread: */ + if (lck->lock_owner == (long) _thread_run) + return; + } + + /* The running thread now owns the lock: */ + lck->lock_owner = (long) _thread_run; +} + +/* + * Lock a location for the running thread. Yield to allow other + * threads to run if this thread is blocked because the lock is + * not available. Note that this function does not sleep. It + * assumes that the lock will be available very soon. + * + * This function checks if the running thread has already locked the + * location, warns if this occurs and creates a thread dump before + * returning. + */ +void +_spinlock_debug(spinlock_t *lck, char *fname, int lineno) +{ + /* + * Try to grab the lock and loop if another thread grabs + * it before we do. + */ + while(_atomic_lock(&lck->access_lock)) { + /* Give up the time slice: */ + sched_yield(); + + /* Check if already locked by the running thread: */ + if (lck->lock_owner == (long) _thread_run) { + char str[256]; + snprintf(str, sizeof(str), "%s - Warning: Thread %p attempted to lock %p from %s (%d) which it had already locked in %s (%d)\n", __progname, _thread_run, lck, fname, lineno, lck->fname, lck->lineno); + _thread_sys_write(2,str,strlen(str)); + + /* Create a thread dump to help debug this problem: */ + _thread_dump_info(); + return; + } + } + + /* The running thread now owns the lock: */ + lck->lock_owner = (long) _thread_run; + lck->fname = fname; + lck->lineno = lineno; +} |
