On Wed, 3 Mar 2004, David Brownell wrote:
> What you seem to be on to is that when there's a fault before that
> "lock down and go" stage commits, the same cancel-must-giveback
> logic must exist ... it's not just on the success path. (And that
> patch only handled the success path, which predominates.)
>
> So maybe some of that logic should exist in hcd_submit_urb(); if
> the (internal) failure were -ENOMSG or somesuch, that could could be
> responsible for the giveback(). I'd support such a patch; better
> than having that particular logic in all the HCDs.
> > shouldn't, because you can't succeed in unlinking an URB that wasn't
> > linked to begin with. (Of course, it really was linked for a brief period
>
> Exactly: it was linked, and that fact was advertised to the rest
> of the kernel. All parts of this story need to agree!
You're saying that this code at the end of hcd_submit_urb() is wrong:
status = hcd->driver->urb_enqueue (hcd, urb, mem_flags);
done:
if (status) {
usb_put_urb (urb);
urb_unlink (urb);
}
return status;
}
Ignore for the moment code paths that reach the done: label via a jump.
Regardless of the status returned by enqueue(), the URB has already been
linked. So hcd_submit_urb() must return 0, not status. If enqueue() does
return non-zero (any value, not just -ENOMSG) then the URB has to be sent
to giveback; calling urb_unlink() is not enough.
Alan Stern
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