From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752801Ab3AUJ1a (ORCPT ); Mon, 21 Jan 2013 04:27:30 -0500 Received: from hotel311.server4you.de ([85.25.146.15]:43929 "EHLO hotel311.server4you.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752558Ab3AUJ12 (ORCPT ); Mon, 21 Jan 2013 04:27:28 -0500 Message-ID: <50FD09FD.4010804@monom.org> Date: Mon, 21 Jan 2013 10:27:25 +0100 From: Daniel Wagner User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Li Zefan CC: John Fastabend , Neil Horman , Daniel Wagner , LKML , netdev@vger.kernel.org, Cgroups Subject: Re: [BUG] Bug in netprio_cgroup and netcls_cgroup ? References: <50FCDB5C.4050608@huawei.com> <50FD0144.1000401@monom.org> <50FD0402.6060400@huawei.com> In-Reply-To: <50FD0402.6060400@huawei.com> Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21.01.2013 10:01, Li Zefan wrote: > On 2013/1/21 16:50, Daniel Wagner wrote: >> Hi Li, >> >> On 21.01.2013 07:08, Li Zefan wrote: >>> I'm not a network developer, so correct me if I'm wrong. >>> >>> Since commit 7955490f732c2b8 >>> ("net: netprio_cgroup: rework update socket logic"), sock->sk->sk_cgrp_prioidx >>> is set when the socket is created, and won't be updated unless the task is >>> moved to another cgroup. >>> >>> Now the problem is, a socket can be _shared_ by multiple processes (fork, SCM_RIGHT). >>> If we place those processes in different cgroups, and each cgroup has >>> different configs, but all of the processes will send data via this socket >>> with the same network priority. >> >> Wouldn't that be addressed by 48a87cc26c13b68f6cce4e9d769fcb17a6b3e4b8 >> >> net: netprio: fd passed in SCM_RIGHTS datagram not set correctly >> >> A socket fd passed in a SCM_RIGHTS datagram was not getting >> updated with the new tasks cgrp prioidx. This leaves IO on >> the socket tagged with the old tasks priority. >> >> To fix this add a check in the scm recvmsg path to update the >> sock cgrp prioidx with the new tasks value. >> >> As I read this this should work for net_prio. >> > > But after process A passed the socket fd to B, both A and B can use the > same socket to send data, right? Then if A and B were placed in different > cgroups with differnt configs, A's config won't take effect anymore. > > Am I missing something? I don't know. I guess at one point the socket resources are shared and then one configuration is taking preference. As you can see I am far away of being an expert in this field. Hopefully someone who understands this bits can chip in. BTW, isn't this a similar to what should happen with the block io cgroup? What is the behavior with a fd writing to a file in the scenario you describe above?