Subject: Re: [PATCH 1/9] net classifier: dont allow filters on semi-classful qdisc

From: Stephen Hemminger <[email-masked]>
Date: Fri, 6 Aug 2010 14:58:18 -0700

On Fri, 06 Aug 2010 23:24:47 +0200
Jarek Poplawski <[email-masked]> wrote:

> Stephen Hemminger wrote, On -10.01.-28163 20:59:
> 
> > There are several qdisc which only support a single class (sfq, mq, tbf)
> > and the kernel would dereference a null pointer (bind_tcf), if a user
> > attempted to apply a filter one of these classes.
> 
> 
> mq and tbf can't have this issue because they don't have
> .tcf_chain class method. sfq should support it on purpose
> after this patch:
> 
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=7d2681a6ff4f9ab5e48d02550b4c6338f1638998
> and needs tiny fix only.

Probably best to fix both ways.  Fix sfq to allow filters to
be chained, and fix API to prevent refuse to allow qdisc to
register with tcf_chain && !bind_tcf