netdev - Re: [PATCH] net: add net namespace inode for all net

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Date:   Wed, 10 Mar 2021 09:22:34 +0000
From:   Lorenz Bauer <lmb@...udflare.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Tony Lu <tonylu@...ux.alibaba.com>,
        "David S . Miller" <davem@...emloft.net>, rostedt@...dmis.org,
        mingo@...hat.com, Networking <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: add net namespace inode for all net_dev events

On Tue, 9 Mar 2021 at 20:12, Eric Dumazet <eric.dumazet@...il.com> wrote:
>
> On 3/9/21 5:43 AM, Tony Lu wrote:
> > There are lots of net namespaces on the host runs containers like k8s.
> > It is very common to see the same interface names among different net
> > namespaces, such as eth0. It is not possible to distinguish them without
> > net namespace inode.
> >
> > This adds net namespace inode for all net_dev events, help us
> > distinguish between different net devices.
> >
> > Output:
> >   <idle>-0       [006] ..s.   133.306989: net_dev_xmit: net_inum=4026531992 dev=eth0 skbaddr=0000000011a87c68 len=54 rc=0
> >
> > Signed-off-by: Tony Lu <tonylu@...ux.alibaba.com>
> > ---
> >
>
> There was a proposal from Lorenz to use netns cookies (SO_NETNS_COOKIE) instead.
>
> They have a guarantee of being not reused.
>
> After 3d368ab87cf6681f9 ("net: initialize net->net_cookie at netns setup")
> net->net_cookie is directly available.

The patch set is at
https://lore.kernel.org/bpf/20210219154330.93615-1-lmb@cloudflare.com/
but I decided to abandon it. I can work around my issue by comparing
the netns inode of two processes, which is "good enough" for now.

-- 
Lorenz Bauer  |  Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK

www.cloudflare.com