osfmk/kern/wait_queue.c

1636 	thread_t fifo_thread = THREAD_NULL;
1704 				if (fifo_thread == THREAD_NULL) {
1705 					fifo_thread = t;
1742 	if (fifo_thread != THREAD_NULL) {
1743 		thread_lock(fifo_thread);
1744 		remqueue((queue_entry_t) fifo_thread);
1745 		fifo_thread->wait_queue = WAIT_QUEUE_NULL;
1746 		fifo_thread->wait_event = NO_EVENT64;
1747 		fifo_thread->at_safe_point = FALSE;
1748 		return fifo_thread;	/* still locked */