netdev - Re: [PATCH v3 net] geneve: fix TOS inheriting for ipv4

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Message-ID: <20220802164350.GA11906@pc-4.home>
Date:   Tue, 2 Aug 2022 18:43:50 +0200
From:   Guillaume Nault <gnault@...hat.com>
To:     Matthias May <matthias.may@...termo.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, nicolas.dichtel@...nd.com,
        eyal.birger@...il.com, linux-kernel@...r.kernel.org,
        jesse@...ira.com, pshelar@...ira.com, tgraf@...g.ch
Subject: Re: [PATCH v3 net] geneve: fix TOS inheriting for ipv4

On Tue, Aug 02, 2022 at 02:20:25PM +0200, Matthias May wrote:
> The current code retrieves the TOS field after the lookup
> on the ipv4 routing table. The routing process currently
> only allows routing based on the original 3 TOS bits, and
> not on the full 6 DSCP bits.
> As a result the retrieved TOS is cut to the 3 bits.
> However for inheriting purposes the full 6 bits should be used.
> 
> Extract the full 6 bits before the route lookup and use
> that instead of the cut off 3 TOS bits.
> 
> This patch is the functional equivalent for IPv4 to the patch
> "geneve: do not use RT_TOS for IPv6 flowlabel"

This last sentence assumes this patch and your IPv6 series are going to
be merged roughly at the same time and with the same title. There's
no such guarantee though. So I think we can just drop the reference to
the IPv6 patch. But wait a day or two before sending a new version:
others might have different opinion, maintainers might want to apply
the patch as is or adjust the message manually, someone may have other
points to comment on...

Anyway, the rest of the commit message and the code look good to me.
Thanks for fixing this!

Acked-by: Guillaume Nault <gnault@...hat.com>