netdev - Re: [BUG] Bug in netprio_cgroup and netcls

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Date:	Mon, 21 Jan 2013 09:50:12 +0100
From:	Daniel Wagner <wagi@...om.org>
To:	Li Zefan <lizefan@...wei.com>
CC:	John Fastabend <john.r.fastabend@...el.com>,
	Neil Horman <nhorman@...driver.com>,
	Daniel Wagner <daniel.wagner@...-carit.de>,
	LKML <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org,
	Cgroups <cgroups@...r.kernel.org>
Subject: Re: [BUG] Bug in netprio_cgroup and netcls_cgroup ?

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.

> Similar with cls cgroup.

but not for cls_cgroup because I forgot to apply that fix as well. Just
a sec, about to
send a patch for this.

Thanks for looking into this!

cheers,
daniel



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