> > Will someone at least prevent the device management calls
> > from being called in_interrupt() though? That is _guaranteed_
> > to oops with driver bugs. Even Johannes admitted that he's
> > broken the EHCI and OHCI drivers.
> >
> > The simple fix is to move the call to
> >
> > dev->bus->deallocate(dev)
> >
> > from the memory management stuff (usb_free_dev) to the
> > device management, at the very end of usb_disconnect().
> > Then dev->bus should be nulled.
>
> Could you explain to me the difference between memory management and
> device management in the example of usb-ohci?
Look at "ohci-hcd" instead. And you might have different
terms you'd prefer ... looking specifically at the disconnect
paths:
"Memory Management" is what you're doing with refcounting.
(This style is often called "poor man's garbage collection".)
-> struct usb_device memory ... kfree() when last known
pointer goes away.
"Device Management" is where state associated with the
device's current configuration needs get cleaned up. The
stuff coupled to the "real hardware" which just went away.
-> EDs for that device that are still linked ... need to
block in the driver until we know the HC isn't using
these EDS any longer
-> any TDs on such EDs (reflecting driver bugs FWIW,
they should all have been unlinked already) must be
scrubbed out.
-> then free that ED/TD memory once the HC is known
not to be using it any more.
It's much the same for EHCI: any QH still linked has got
to get unlinked before the kernel state for the device is
really and truly gone. (And before its device address
can be reused on that bus, FWIW ... not that anyone is
likely to disable the round-robin addressing lately.)
Yes, your "uhci" code tracks such state differently.
- Dave
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