Fix a race condition in pthread_join(). All of the following must occur

atomically:

1) Search _thread_list for the thread to join.
2) Search _dead_list for the thread to join.
3) Set the running thread as the joiner.

While we're at it, fix a race in the case where multiple threads try to
join on the same thread.  POSIX says that the behavior of multiple joiners
is undefined, but the fix is cheap as a result of the other fix.

1 files changed, 0 insertions, 32 deletions

diff --git a/lib/libpthread/thread/thr_find_thread.c b/lib/libpthread/thread/thr_find_thread.c
index 861c4cb..e6e9294 100644
--- a/lib/libpthread/thread/thr_find_thread.c
+++ b/lib/libpthread/thread/thr_find_thread.c
@@ -64,35 +64,3 @@ _find_thread(pthread_t pthread)
 	/* Return zero if the thread exists: */
 	return ((pthread1 != NULL) ? 0:ESRCH);
 }
-
-/* Find a thread in the linked list of dead threads: */
-int
-_find_dead_thread(pthread_t pthread)
-{
-	pthread_t pthread1;
-
-	/* Check if the caller has specified an invalid thread: */
-	if (pthread == NULL || pthread->magic != PTHREAD_MAGIC)
-		/* Invalid thread: */
-		return(EINVAL);
-
-	/*
-	 * Lock the garbage collector mutex to ensure that the garbage
-	 * collector is not using the dead thread list.
-	 */
-	if (pthread_mutex_lock(&_gc_mutex) != 0)
-		PANIC("Cannot lock gc mutex");
-
-	/* Search for the specified thread: */
-	TAILQ_FOREACH(pthread1, &_dead_list, dle) {
-		if (pthread1 == pthread)
-			break;
-	}
-
-	/* Unlock the garbage collector mutex: */
-	if (pthread_mutex_unlock(&_gc_mutex) != 0)
-		PANIC("Cannot lock gc mutex");
-
-	/* Return zero if the thread exists: */
-	return ((pthread1 != NULL) ? 0:ESRCH);
-}