device, the device is probed multiple times (so each device is
detected N times after unloading/loading the module N-1 times).
The real fix is (quote Doug and Warner):
> : In an ideal world, there should be some kind of BUS_UNIDENTIFY method
> : which a driver could use to delete the devices it created in
> : BUS_IDENTIFY.
>
> Or the bus would have a driver deleted routine that got called and it
> would remove all instances of the devclass attached to it.
Reviewed by: Doug Rabson & Warner Losh
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