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Subject: Re: [PATCH] net: add net namespace inode for all net_dev events
To:     Tony Lu <tonylu@linux.alibaba.com>, davem@davemloft.net,
        rostedt@goodmis.org, mingo@redhat.com,
        Lorenz Bauer <lmb@cloudflare.com>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210309044349.6605-1-tonylu@linux.alibaba.com>
From:   Eric Dumazet <eric.dumazet@gmail.com>
Message-ID: <203c49a3-6dd8-105e-e12a-0e15da0d4df7@gmail.com>
Date:   Tue, 9 Mar 2021 21:12:45 +0100
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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@linux.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.