netdev - Re: RFC: bring UP 'lo' by default after creating new netns

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Date:   Thu, 29 Jun 2017 20:08:58 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Mahesh Bandewar (महेश बंडेवार) <maheshb@...gle.com>
Cc:     Eric Dumazet <edumazet@...gle.com>, adobriyan@...il.com,
        David Miller <davem@...emloft.net>, xiyou.wangcong@...il.com,
        linux-netdev <netdev@...r.kernel.org>
Subject: Re: RFC: bring UP 'lo' by default after creating new netns

"Mahesh Bandewar (महेश बंडेवार)" <maheshb@...gle.com> writes:

> Creation of new network namespace is almost always followed up by
> bringing up the loopback device.
>
>         ip netns add foo
>         ip -netns foo link set lo up
>
> I'm not sure if there are any consequences of bringing the device UP
> at the creation of network-namespace.

Hard coded in net/core/net_namespace.c:copy_net_ns is definitely the
wrong place in the code for something like this.  If this lives anywhere
it should live in driver/net/loopback.c, or possibly in
net/core/dev.c:net_dev_init.

If we want this we want to match what we do when we the primary network
namespace.  Just so that there are no unneeded surprises with network
namespaces.

Eric