On Tuesday 15 January 2002 19:42, David Brownell wrote:
> > The problem is basically that the usbcore in case of an unlink has
> > to wait while the hardware might be dealing with an urb and the
> > completion handler is running.
>
> Classic urb-unlink issue inside the hcd, doesn't need
> to be exposed outside. Any given URB is either going
> to have completed normally, or be partially complete
> (including zero bytes), when the hardware stops work
> on it. The hcd only needs to report it appropriately.
I really doubt that this issue can be not exposed.
If I may point you to the following code path:
usb_unlink_urb -> sohci_unlink_urb
There you find a huge amount of usage of the urb pointer
the driver has supplied.
Yet usb_unlink_urb and the completion handler can race,
at least on SMP. I can see really no way that API is supposed
to work if the urb can be freed in the completion handler.
Regards
Oliver
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