From: Chris J Arges <chris.j.arges@canonical•com>
To: "Eric W. Biederman" <ebiederm@xmission•com>
Cc: shemminger@osdl•org, netdev@vger•kernel.org
Subject: Re: iproute2: potential upgrade regression with 58a3e827
Date: Fri, 08 Nov 2013 16:30:19 -0600 [thread overview]
Message-ID: <527D65FB.8000407@canonical.com> (raw)
In-Reply-To: <87k3gi4lub.fsf@xmission.com>
On 11/08/2013 03:36 PM, Eric W. Biederman wrote:
> Chris J Arges <chris.j.arges@canonical•com> writes:
>
>> Hi,
>> The commit
>> https://git.kernel.org/cgit/linux/kernel/git/shemminger/iproute2.git/commit/?id=58a3e8270fe72f8ed92687d3a3132c2a708582dd
>> could be potentially introducing a regression on an upgrade.
>>
>> I've noticed that upgrading iproute while there are active namespaces
>> could cause the following error:
>> seting the network namespace failed: Invalid argument
>>
>> Here's a test case:
>> Build and install iproute2 with 4395d48c78a77a99c5a8618403211032356fe552
>>
>> In one terminal run:
>> ip netns add netns_old
>> ip link add name if_old type veth peer name if_old_peer
>> ip link set dev if_old_peer netns netns_old
>> ip netns exec netns_old bash
>>
>> Build and install iproute2 with 58a3e8270fe72f8ed92687d3a3132c2a708582dd
>>
>> In the same terminal as you typed the original commands run:
>> ip netns add netns_one
>> ip link add name if_one type veth peer name if_one_peer
>> ip link set dev if_one_peer netns netns_one
>> ip netns exec netns_one bash
>> ip netns exec netns_old bash
>>
>> You'll get:
>> seting the network namespace failed: Invalid argument
>>
>> If you just run the above without transitioning to the code in 58a3e827,
>> then it works.
>
> ip netns exec is fundamentally designed to run code that knows nothing
> about network namespaces without modification. If we can make network
> namespace aware code work that is great but the entire point of ip netns
> exec is to remove the need to convert every network aware program in
> linux to be network namespace aware.
>
> Shared subtree support that is added in 58a3e827 should make things a
> little better, by letting changes that happen in the initial mount
> namespace propogate into children running inside of ip netns exec.
>
> It appears that somehow you wound up in a mount namespace where the
> mount of netns_one did not propagate too. Which is weird. I expect
> we are missing an error message somewhere.
>
> So far nothing allows network namespaces added like:
> ip netns exec ns1 ip netns add ns2
> to propogate up to the initial mount namespace and that will definitely
> cause problems, but not the problem you are seeing.
>
> Shrug. I will be happy to review patches to make this better but I
> don't care enough to investigate. If you aren't up to writing patches
> to make ip netns work inside of ip netns exec I recommend you don't do
> that then.
>
> Eric
Fair enough. I really wanted to get a feel if this seemed like an actual
bug, or rather it's behaving like we'd expect. I don't mind writing
code, but I want to know if I'm hunting a bug, or adding a feature.
Thanks for the quick reply,
--chris j arges
next prev parent reply other threads:[~2013-11-08 22:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-08 18:03 iproute2: potential upgrade regression with 58a3e827 Chris J Arges
2013-11-08 21:36 ` Eric W. Biederman
2013-11-08 22:30 ` Chris J Arges [this message]
2013-11-08 22:42 ` Eric W. Biederman
2013-11-09 17:00 ` Brian Haley
2013-11-11 21:26 ` Chris J Arges
2013-11-11 21:38 ` Dilip Daya
2013-11-11 22:40 ` Eric W. Biederman
2013-11-12 0:36 ` Dilip Daya
2013-12-13 18:46 ` [PATCH] " Chris J Arges
2013-12-13 18:55 ` Stephen Hemminger
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