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Date: Thu, 5 Mar 2026 13:20:43 +0100
From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: netdev@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, netfilter-devel@vger.kernel.org
Subject: Re: [PATCH net 0/4] netfilter: updates for net
Message-ID: <aal1G5h9AWfY8OgS@strlen.de>
References: <20260304172940.24948-1-fw@strlen.de>
 <aaiqrFrus1syOmlT@chamomile>
 <aalHS6-11HUHy-Dd@strlen.de>
 <aalPfgw5Ypsik8NY@chamomile>
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In-Reply-To: <aalPfgw5Ypsik8NY@chamomile>

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > Yes, it looks broken.  I wonder why we have no tests for this stuff.
> > First a vlan push function that cannot have worked, ever, now this
> > seemingly reversing-headers variant:
> 
> This used to work, I just accidentally broke it when using
> skb_vlan_push() in net-next.
> 
> I will post fix.

Ok, thanks.

> > For PPPOE, its pushing the ppppe header to packet, so we get
> > strict ordering, later header coming in the stack gets placed on
> > top, before older one.
> > 
> > Here, first vlan push gets placed into hw tag in skb (which makes
> > sense, let HW take care of it).
> >
> > But if 2nd comes along, then that gets placed in the packet
> > and the hwaccel tag remains?
> >
> > What to do?  Should be nuke vlan offload support from flowtable?
> > It appears to be an unused feature.
> >
> > I have low confidence in this code.
> 
> Could you elaborate more precisely?

Add bug in nf_queue -> kselftest will likely barf
Add bug in nf_tables control plane -> nftables shell and/or
python tests will likely barf
Add bug in conntrack -> kselftest will likely barf

Add new bug in flowtable vlan -> nada.

I think we should refuse both new features and refactoring patches going
forward unless they come with either update to existing kselftest, or a
new test or a test in nftables.git.