Message-ID: <54535B00.5090708@6wind.com>
Date: Fri, 31 Oct 2014 10:48:48 +0100
From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reply-To: nicolas.dichtel@6wind.com
Organization: 6WIND
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0
MIME-Version: 1.0
To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: netdev@vger.kernel.org, containers@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        davem@davemloft.net, stephen@networkplumber.org,
        akpm@linux-foundation.org, luto@amacapital.net, cwang@twopensource.com
Subject: Re: [PATCH net-next v4 0/4] netns: allow to identify peer netns
References: <1412257690-31253-1-git-send-email-nicolas.dichtel@6wind.com>	<1414682728-4532-1-git-send-email-nicolas.dichtel@6wind.com> <871tpph03k.fsf@x220.int.ebiederm.org>
In-Reply-To: <871tpph03k.fsf@x220.int.ebiederm.org>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org

Le 30/10/2014 19:41, Eric W. Biederman a écrit :
> Nicolas Dichtel <nicolas.dichtel@6wind.com> writes:
>
>> The goal of this serie is to be able to multicast netlink messages with an
>> attribute that identify a peer netns.
>> This is needed by the userland to interpret some informations contained in
>> netlink messages (like IFLA_LINK value, but also some other attributes in case
>> of x-netns netdevice (see also
>> http://thread.gmane.org/gmane.linux.network/315933/focus=316064 and
>> http://thread.gmane.org/gmane.linux.kernel.containers/28301/focus=4239)).
>>
>> Ids of peer netns are set by userland via a new genl messages. These ids are
>> stored per netns and are local (ie only valid in the netns where they are set).
>> To avoid allocating an int for each peer netns, I use idr_for_each() to retrieve
>> the id of a peer netns. Note that it will be possible to add a table (struct net
>> -> id) later to optimize this lookup if needed.
>>
>> Patch 1/4 introduces the netlink API mechanism to set and get these ids.
>> Patch 2/4 and 3/4 implements an example of how to use these ids in rtnetlink
>> messages. And patch 4/4 shows that the netlink messages can be symetric between
>> a GET and a SET.
>>
>> iproute2 patches are available, I can send them on demand.
>
> A quick reply.  I think this patchset is in the right general direction.
> There are some oddball details that seem odd/awkward to me such as using
> genetlink instead of rtnetlink to get and set the ids, and not having
> ids if they are not set (that feels like a maintenance/usability challenge).
No problem to use rtnetlink, in fact, I hesitated.

For the second point, I'm not sure to follow you: how to have an id, which will
not break migration, without asking the user to set it?
Note that if the user does not provide an id, you still have a magic value to
say "it's a peer netns but we don't know which one".

>
> I would like to give your patches a deep review, but I won't be able to
> do that for a couple of weeks.  I am deep in the process of moving,
> and will be mostly offline until about the Nov 11th.

No problem, I will wait.
I would be great to get a final version for the 3.19 ;-)


Thank you,
Nicolas
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/