From: "Mahesh Bandewar (महेश बंडेवार)" <maheshb@google.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Eric Dumazet <edumazet@google.com>,
adobriyan@gmail.com, David Miller <davem@davemloft.net>,
xiyou.wangcong@gmail.com, linux-netdev <netdev@vger.kernel.org>
Subject: Re: RFC: bring UP 'lo' by default after creating new netns
Date: Thu, 29 Jun 2017 23:26:46 -0700 [thread overview]
Message-ID: <CAF2d9jg1P2AVOJ+FT+pRGjG0HW1YCRN9+WQ7xK67banby7EMng@mail.gmail.com> (raw)
In-Reply-To: <87efu22set.fsf@xmission.com>
On Thu, Jun 29, 2017 at 6:08 PM, Eric W. Biederman
<ebiederm@xmission.com> wrote:
> "Mahesh Bandewar (महेश बंडेवार)" <maheshb@google.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.jjh
>
> 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.
>
interestingly dev_open() needs RTNL while it's not recommended at
net_dev_init() time.
Also net_dev_init() is called at the sub-system registration, do you
mean loopback_net_init() time?
> 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.
>
Yes, correct, it should be same whether it's init-net or some other. I
can add the IFF_UP flag during
loopback_setup() but then it will not perform anything that is done
during dev_open() phase. I'll try
moving the code to loopback_net_init() to achieve the same result so
that I can avoid that hard-coding too.
Thanks for comments Eric.
--mahesh..
> Eric
prev parent reply other threads:[~2017-06-30 6:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-29 23:57 RFC: bring UP 'lo' by default after creating new netns Mahesh Bandewar (महेश बंडेवार)
2017-06-30 1:08 ` Eric W. Biederman
2017-06-30 6:26 ` Mahesh Bandewar (महेश बंडेवार) [this message]
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