netdev - Re: [PATCH net-next] net:sched: add action inheritdsfield to skbmod

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Message-ID: <CAM_iQpWJ0=w5A5+onbF-Ngo+emgHm-JMpyJdWONt2NWRu9Kk2w@mail.gmail.com>
Date:   Wed, 23 May 2018 16:01:17 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     "Fu, Qiaobin" <qiaobinf@...edu>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "jhs@...atatu.com" <jhs@...atatu.com>,
        Michel Machado <michel@...irati.com.br>
Subject: Re: [PATCH net-next] net:sched: add action inheritdsfield to skbmod

On Thu, May 17, 2018 at 12:33 PM, Fu, Qiaobin <qiaobinf@...edu> wrote:
> net/sched: add action inheritdsfield to skbmod
>
> The new action inheritdsfield copies the field DS of
> IPv4 and IPv6 packets into skb->prioriry. This enables
> later classification of packets based on the DS field.
>
> Original idea by Jamal Hadi Salim <jhs@...atatu.com>
>
> Signed-off-by: Qiaobin Fu <qiaobinf@...edu>
> Reviewed-by: Michel Machado <michel@...irati.com.br>

Hmm, but skbedit seems better than skbmod for this job,
given:

1) It already modifies skb->priority, although with a given value

2) skbmod doesn't change skb metadata, it only changes payload

I am _not_ saying there is strict rule for what skbmod can or can't
change, it calls itself "data modifier", so I am saying we probably
need to follow this existing practice.