linux-kernel - Re: [PATCH] net: dev_forward_skb(): Scrub packet's per-netns info only when crossing netns

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Date:   Thu, 15 Mar 2018 18:11:47 +0200
From:   Shmulik Ladkani <shmulik.ladkani@...il.com>
To:     Liran Alon <liran.alon@...cle.com>
Cc:     <mrv@...atatu.com>, <netdev@...r.kernel.org>,
        <daniel@...earbox.net>, <davem@...emloft.net>,
        <linux-kernel@...r.kernel.org>, <yuval.shaia@...cle.com>,
        <idan.brown@...cle.com>
Subject: Re: [PATCH] net: dev_forward_skb(): Scrub packet's per-netns info
 only when crossing netns

On Thu, 15 Mar 2018 08:01:03 -0700 (PDT) Liran Alon <liran.alon@...cle.com> wrote:
> 
> I still think that default behavior should be to zero skb->mark only when skb
> cross netdevs in different netns.

But the previous default was scrub the mark in *both* xnet and non-xnet
situations.

Therefore, there might be users which RELY on this (strange) default
behavior in their same-netns-veth-pair setups.
Meaning, changing the default behavior might break their apps relying on
the former default behavior.

This is why the "disable mark scrubbing in non-xnet case" should be opt-in.

Regards,
Shmulik