In particular:
- Don't leave resources allocated in the probe routine. Allocate them
during probe and release them. Probe's job is to identify devices only.
- Don't abuse the ivars pointer.. (!). Create real ivars and use the
proper access system. (the bus_read_ivar method)
- Don't add the children until attach() has successfully grabbed the
hardware, otherwise there are potential leaks if attach fails.
37286586ff