netdev - Re: [RFC PATCH 1/1 v2] net: sched: Introduce conndscp action

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Message-ID: <F859B266-4F56-427F-828E-FB725EF0919D@darbyshire-bryant.me.uk>
Date:   Wed, 27 Mar 2019 20:32:24 +0000
From:   Kevin 'ldir' Darbyshire-Bryant <ldir@...byshire-bryant.me.uk>
To:     Cong Wang <xiyou.wangcong@...il.com>
CC:     "jhs@...atatu.com" <jhs@...atatu.com>,
        "jiri@...nulli.us" <jiri@...nulli.us>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [RFC PATCH 1/1 v2] net: sched: Introduce conndscp action

Hi Cong,

Thanks for getting back to me once again and apologies for the delayed reply.

> On 25 Mar 2019, at 19:17, Cong Wang <xiyou.wangcong@...il.com> wrote:
> 
> On Sat, Mar 23, 2019 at 10:45 AM Kevin 'ldir' Darbyshire-Bryant
> <ldir@...byshire-bryant.me.uk> wrote:
>> 
>> I will remove the functionality from conndscp that changes the conntrack mark, so that it only restores the mark into the diffserv field.
>> 
>> So that I’m clear about which direction I should be headed:
>> 
>> Bearing in mind that conndscp writes to the skb’s iphdr diffserv field and *not* skb->fwmark, do you still desire to see the dscp restoration code done as part of connmark.  In other words NOT have a separate conndscp module?
>> 
> 
> For me, the barrier is the name "connmark" is confusing if we put conndscp
> into it. So, I think leaving conndscp alone is fine.
> 
> Perhaps we just need an action called "act_conntrack" which could retrieve
> any meaningful information from conntrack to skb.
> 
> What do you think?

Hmm.  A number of thoughts flash through the brain cell: 1) I obviously can’t think of anything else that would/could sensibly be restored from conntrack to skb, but then to my knowledge no one else has yet wanted to restore DSCP, so that’s hardly a good excuse.  2) laziness/fear/lack of skill, I’ve no idea how to go about coding something like that in an extendable, quick and efficient manner.  3) keeping it simple.

I’m working on a simplified conndscp, probably a few days yet for testing/checking - see if that ends up as something more suitable.

> 
> Thanks.

Cheers,

Kevin D-B

gpg: 012C ACB2 28C6 C53E 9775  9123 B3A2 389B 9DE2 334A