static void d_wait_lookup(struct dentry *dentry)
{
	if (d_in_lookup(dentry)) {
		DECLARE_WAITQUEUE(wait, current);
		add_wait_queue(dentry->d_wait, &wait);
		do {
			set_current_state(TASK_UNINTERRUPTIBLE);
			spin_unlock(&dentry->d_lock);
			schedule();
			spin_lock(&dentry->d_lock);
		} while (d_in_lookup(dentry));
	}
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.