Re: [PATCH] net: cls_api: remove unneeded local variable in tc_dump_chain()

Cong Wang <[email protected]> Wed, 28 Oct 2020 10:38:45 -0700

Newsgroups	tech.elisa.lists.linux-safety,org.kernel.vger.kernel-janitors,org.kernel.vger.linux-kernel,org.kernel.vger.netdev
Message-ID	<CAM_iQpUfE2f3QBFY6r0_D2mzFK_SsmFXdA-1p3h7yquM8912fg@mail.gmail.com>

On Wed, Oct 28, 2020 at 6:59 AM Tom Rix <[email protected]> wrote:
>
>
> On 10/28/20 4:35 AM, Lukas Bulwahn wrote:
> > @@ -2971,13 +2963,11 @@ static int tc_dump_chain(struct sk_buff *skb, struct netlink_callback *cb)
> >               if (!dev)
> >                       return skb->len;
> >
> > -             parent = tcm->tcm_parent;
> > -             if (!parent) {
> > +             if (!tcm->tcm_parent)
> >                       q = dev->qdisc;
> > -                     parent = q->handle;
>
> This looks like a an unused error handler.
>
> and the later call to
>
> if (TC_H_MIN(tcm->tcm_parent)
>
> maybe should be
>
> if (TC_H_MIN(parent))

When tcm->tcm_parent is 0, TC_H_MIN(tcm->tcm_parent) is also 0,
so we will not hit that if branch.

So, I think Lukas' patch is correct.

Thanks.