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

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Message-ID: <8b06ac17-e19b-90f3-6dd2-0274a0ee474b@ucloud.cn>
Date:   Wed, 1 Jul 2020 14:02:02 +0800
From:   wenxu <wenxu@...oud.cn>
To:     Cong Wang <xiyou.wangcong@...il.com>
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 7/1/2020 1:52 PM, Cong Wang wrote:
> On Tue, Jun 30, 2020 at 7:36 PM wenxu <wenxu@...oud.cn> wrote:
>>
>> On 7/1/2020 3:02 AM, Cong Wang wrote:
>>> On Mon, Jun 29, 2020 at 7:55 PM <wenxu@...oud.cn> wrote:
>>>> From: wenxu <wenxu@...oud.cn>
>>>>
>>>> The fragment packets do defrag in act_ct module. The reassembled packet
>>>> over the mtu in the act_mirred. This big packet should be fragmented
>>>> to send out.
>>> This is too brief. Why act_mirred should handle the burden introduced by
>>> act_ct? And why is this 158-line change targeting -net not -net-next?
>> Hi Cong,
>>
>> In the act_ct the fragment packets will defrag to a big packet and do conntrack things.
>>
>> But in the latter filter mirred action, the big packet normally send over the mtu of outgoing device.
>>
>> So in the act_mirred send the packet should fragment.
> Why act_mirred? Not, for a quick example, a new action called act_defrag?
> I understand you happen to use the combination of act_ct and act_mirred,
> but that is not the reason we should make act_mirred specifically work
> for your case.

Only forward packet case need do fragment again and there is no need do defrag explicit.