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SubjectRe: S2R resume crash in 2.6.33-rc7 - NULL pointer dereference in dev_get_drvdata() for usbhid
On Sat, 13 Feb 2010, Bruno [UTF-8] Prémont wrote:

> On Mon, 08 February 2010 Alan Stern <stern@rowland.harvard.edu> wrote:
> > Clearly something is setting usbhid->intf to NULL. But I don't see
> > any code that would do it. You may have to resort to putting
> > printk() statements at various strategic places to find out where it
> > happens. You could start with the beginnings and ends of hid_suspend,
> > hid_resume, and hid_reset_resume. Maybe also usbhid_disconnect(),
> > just in case.
>
> I did add a few printk()s and WARN_ON()s to get a better idea of
> why/when usbhid->intf is NULL and it is already since probe time of the
> second interface anounced by the USB keyboard (hid.debug=1):

...

> This lets me guess that hid_add_device() is doing something wrong
> here when report parsing fails... (as that one is the only one which
> could be doing the initialization of usbhid which does work for the
> first interface announced by my keyboard)

I don't know about doing anything wrong... However it does appear that
in this case the interface is registered on the HID bus but doesn't get
bound to a driver. Jiri will know whether or not that's the desired
outcome.

On the other hand, I don't think there would be anything wrong with
moving the

usbhid->intf = intf;
usbhid->ifnum = interface->desc.bInterfaceNumber;

lines from usbhid_start() to usbhid_probe(), just before the call to
hid_add_device(). It should fix the bug, and those lines do belong in
the probe routine. Jiri, any problems with doing this?

Alan Stern

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