On Wed, 23 Jul 2008, David Brownell wrote:

quoted text
> So far, the fingers point at dummy_hcd... the merge doesn't
> seem to have had problems, and the gadget driver had been
> tested with four different peripheral controller drivers
> (pre-merge).

quoted text
> But the link state notification (probably using ep-e) message
> couldn't be queued (list_add_tail) because of this oopsing:
> 
> 
> > usb0: qlen 10
> > g_cdc gadget: notify connect false
> > list_add corruption. prev->next should be next (ffff88003b8f82f8), but was ffff88003b8f8e80. (prev=ffff88003b8f8e80).
> 
> Now, prev->next == prev is expected here:  that list of messages
> should be empty.
> 
> What's wrong is that head->prev != head, meaning something
> trashed a dummy_hcd data structure.

The problem could easily be that dummy-hcd simply isn't 
list-debugging-safe.  I wouldn't be at all surprised if, for example, 
it adds a node to a list without initializing the node first.

Alan Stern

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