multiple interface test case

[Duncan Sands]

Hi Roman,

> I would be surprized if the problem is triggered only if you grab a
> _bunch_, and AFAICT there are quite a few drivers which grab at least
> one via usb_driver_claim_interface and then release it via
> usb_driver_release_interface, and thus should hit it too (unless there's
> something like an off-by-one error which is triggered only when you grab
> _all_ interfaces).

I just tried rmmod usbnet for a two interface device and it hung.  That
could be for a different reason - there were some messages from the
networking subsystem about its reference counts.  That could be either
a reason for or a consequence of the rmmod hang.

D.