Hi Robert,
On Wed, Feb 23, 2011 at 09:17:41AM +0000, Robert Pearce wrote:
> Hi Dmitry,
>
> On Wed, 23 Feb 2011 00:54:37 -0800 you wrote:
> >
> > which happens because port_array[] is u8 so after integer promotion
> > the value is between 0 - 255 (no sign extension happens) but we
> > compare it with -1.
> >
> >
> > As far as I can see this is a real issue, still compiled only at this
> > time.
> >
> <snip>
> > */
> > if (xhci->port_array[i] != major_revision &&
> > - xhci->port_array[i] != (u8) -1) {
> > + xhci->port_array[i] != XHCI_PORT_IGNORE) {
> > if (xhci->port_array[i] == 0x03)
> > xhci->num_usb3_ports--;
> > else
> > xhci->num_usb2_ports--;
> > - xhci->port_array[i] = (u8) -1;
> > + xhci->port_array[i] = XHCI_PORT_IGNORE;
> > }
>
> I think you're misreading it. The lines you've replaced are comparing
> against "(u8) -1", which is the value -1 but cast to a u8. The result
> is the same 0xFF that you've replaced it with.
>
> Not that an explicit #define isn't better, but the patch should not be
> described as fixing a bug when all it does is tidy up the code.
Actually in the other chunk you removed there was a comparison with a
naked -1 so the patch in fact does fix a problem.
Thanks.
--
Dmitry
P.S. Please do reply-all on the kernel lists, in ensures quicker
responses as not everyone subscribed everywhere.
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