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Diffstat (limited to 'lib/libpthread/thread/thr_spinlock.c')
-rw-r--r-- | lib/libpthread/thread/thr_spinlock.c | 65 |
1 files changed, 65 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..b2fe269 --- /dev/null +++ b/lib/libpthread/thread/thr_spinlock.c @@ -0,0 +1,65 @@ +/* + * 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. + * + * $Id$ + * + */ + +#include <stdio.h> +#include <sched.h> +#include <unistd.h> +#include <pthread.h> +#include "spinlock.h" +#include "pthread_private.h" + +/* + * 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(long *lck) +{ + do { + /* + * Allow other threads to run if the lock is not + * available: + */ + while (*lck != 0) + sched_yield(); + + /* + * Try to grab the lock and loop if another thread grabs + * it before we do. + */ + } while(_atomic_lock(lck,(long) _thread_run)); +} |