Re: [linux-usb-devel] Re: [OOPS, usbcore, releaseintf] 2.6.0-test10-mm1

[Duncan Sands]

> In an earlier message I wrote that the HC driver couldn't unload so long
> as the device usbfs was using held a reference to its bus.  I just did
> some checking, and guess what: It can!

Uh oh.

> I looked at both the UHCI and OHCI drivers.  In their module_exit routines
> they call pci_unregister_driver().  Without knowing how the PCI subsystem
> works, I would assume this behaves like any other "deregister" routine in
> the driver model and returns without waiting for any reference count to go
> to 0 -- that's what release callbacks are for.
>
> However, the module_exit routines _don't_ wait for the release callbacks.
> They just go right on ahead and exit.  Result: when the reference count
> eventually does go to 0 (when usbfs drops its last reference), the
> hcd_free routine is no longer present and you get an oops.
>
> The proper fix would be to have each HC driver keep track of how many
> instances are allocated.  The module_exit routine must wait for that
> number to drop to 0 before returning.

Is this how it is usually done?

All the best,

Duncan.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/