void kill ()
    {
	if (Linux.trace)
	    System.err.println ("kill bus" + this);

	// notify any listeners that the bus died, and
	// clear backlinks that we control
	if (listeners.size () > 0) {
	    synchronized (devices) {
		for (int i = 0; i < devices.length; i++) {
		    if (devices [i] == null)
			continue;
		    removed (devices [i]);
		}
	    }
	}
    }