netdev - Re: [PATCH net] net/sched: act_mirred: fix fragment the packet after defrag in act

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Message-ID: <CAM_iQpV_1_H_Cb3t4hCCfRXf2Tn2x9sT0vJ5rh6J6iWQ=PNesA@mail.gmail.com>
Date:   Wed, 1 Jul 2020 10:33:46 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     wenxu <wenxu@...oud.cn>
Cc:     Paul Blakey <paulb@...lanox.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net/sched: act_mirred: fix fragment the packet after
 defrag in act_ct

On Wed, Jul 1, 2020 at 1:21 AM wenxu <wenxu@...oud.cn> wrote:
>
>
> On 7/1/2020 2:21 PM, wenxu wrote:
> > On 7/1/2020 2:12 PM, Cong Wang wrote:
> >> On Tue, Jun 30, 2020 at 11:03 PM wenxu <wenxu@...oud.cn> wrote:
> >>> Only forward packet case need do fragment again and there is no need do defrag explicit.
> >> Same question: why act_mirred? You have to explain why act_mirred
> >> has the responsibility to do this job.
> > The fragment behavior only depends on the mtu of the device sent in act_mirred. Only in
> >
> > the act_mirred can decides whether do the fragment or not.
>
> Hi cong,
>
>
> I still think this should be resolved in the act_mirred.  Maybe it is not matter with a "responsibility"
>
> Did you have some other suggestion to solve this problem?

Like I said, why not introduce a new action to handle fragment/defragment?

With that, you can still pipe it to act_ct and act_mirred to achieve
the same goal.

act_mirred has the context to handle it does not mean it has to handle it.
Its name already tells you it only handles mirror or redirection, and
fragmentation is a layer 3 thing, it does not fit well in layer 2 here. This
is why you should think carefully about what is the best place to handle
it, _possibly_ it should not be in TC at all.

Thanks.