On Mon, Nov 07, 2016 at 10:09:17AM +0100, Greg Kroah-Hartman wrote:
> > Rework smelling code (goto inside compound statement). Perhaps this is legacy.
> > Anyway such code is not appropriate for Linux kernel.
> >
> > Signed-off-by: Eugene Korenevsky <ekorenevsky@xxxxxxxxx>
> > ---
> > drivers/usb/core/hub.c | 24 +++++++++++-------------
> > 1 file changed, 11 insertions(+), 13 deletions(-)
>
> What changed from v1?
Fixed faults: missed 'Signed-off-by', spaces instead of tab.
> > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> > index cbb1467..4081672 100644
> > --- a/drivers/usb/core/hub.c
> > +++ b/drivers/usb/core/hub.c
> > @@ -1802,23 +1802,21 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
> >
> > /* Some hubs have a subclass of 1, which AFAICT according to the */
> > /* specs is not defined, but it works */
> > - if ((desc->desc.bInterfaceSubClass != 0) &&
> > - (desc->desc.bInterfaceSubClass != 1)) {
> > -descriptor_error:
> > +
> > + /* Reject in following cases:
> > + * - Interface subclass is not 0 or 1
> > + * - Multiple endpoints
> > + * - Not an interrupt in endpoint
> > + */
> > + endpoint = &desc->endpoint[0].desc;
> > + if ((desc->desc.bInterfaceSubClass != 0 &&
> > + desc->desc.bInterfaceSubClass != 1) ||
> > + desc->desc.bNumEndpoints != 1 ||
> > + !usb_endpoint_is_int_in(endpoint)) {
> > dev_err(&intf->dev, "bad descriptor, ignoring hub\n");
> > return -EIO;
> > }
> >
> > - /* Multiple endpoints? What kind of mutant ninja-hub is this? */
> > - if (desc->desc.bNumEndpoints != 1)
> > - goto descriptor_error;
> > -
> > - endpoint = &desc->endpoint[0].desc;
> > -
> > - /* If it's not an interrupt in endpoint, we'd better punt! */
> > - if (!usb_endpoint_is_int_in(endpoint))
> > - goto descriptor_error;
> > -
>
> As "horrible" as the original code might be, it's much easier to read
> and follow, which is the key thing here, right? What's so bad about a
> goto backwards?
OK, this patch is still not perfect. But jumping *back* into
*compound* *statement* hurts reader's eyes. Really. Maybe it's better to
extract this code to static function, compiler will inline it. See v3
patchset.
--
Eugene
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