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From: Stephen Hemminger <shemminger@vyatta.com>
To: "Bruno Prémont" <bonbons@linux-vserver.org>
Cc: netdev@vger.kernel.org, Greg Rose <gregory.v.rose@intel.com>
Subject: Re: netlink: 12 bytes leftover after parsing attributes - triggered by iproute2 libnetlink's rtnl_dump_request()
Date: Tue, 20 Mar 2012 08:09:17 -0700	[thread overview]
Message-ID: <20120320080917.77765344@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <20120320160023.621e948a@pluto.restena.lu>

On Tue, 20 Mar 2012 16:00:23 +0100
Bruno Prémont <bonbons@linux-vserver.org> wrote:

> On Tue, 20 Mar 2012 07:41:40 Stephen Hemminger wrote:
> > > Should this get fixed at kernel level, iproute2 libnetlink level or
> > > at end-user level (e.g. collectd)?
> > > Three lines every 10 seconds is a damn lot!
> > > 
> > > Thanks,
> > > Bruno
> > 
> > Netlink is supposed to be encoded as Type-Length-Value and correctly written
> > programs ignore types they don't understand. So either the library is getting
> > confused by the type or the attribute is not encoded correctly.
> > 
> > 
> > The issue could be in libnetlink library. What version of collectd and libnetlink
> > are you using?
> 
> I've used collectd-5.0.x and collectd-4.10.3 with 3.3 kernels.
> The stub code I listed is what collectd's netlink plugin does with
> libnetlink (processing of netlink reply factored out for short-ness)
> 
> In all cases, linked against libnetlink from iproute2-2.6.38 (on
> Gentoo)
> 
> 
> From looking at git history of both collectd and iproute2, on both
> sides there has not been any changes that would affect the result.
> 
> Collectd:
>   http://git.verplant.org/?p=collectd.git;a=history;f=src/netlink.c;hb=HEAD

It is most likely in the libnetlink code, I'll look there.  Since libnetlink
is not really an exported API, I wish applications would use a real
library like libmnl instead rather than copying it out of iproute2.

  reply	other threads:[~2012-03-20 15:09 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-03-20 12:41 netlink: 12 bytes leftover after parsing attributes - triggered by iproute2 libnetlink's rtnl_dump_request() Bruno Prémont
2012-03-20 14:41 ` Stephen Hemminger
2012-03-20 15:00   ` Bruno Prémont
2012-03-20 15:09     ` Stephen Hemminger [this message]
2012-03-20 15:00   ` Ben Hutchings
2012-03-21  0:02     ` Stephen Hemminger
2012-04-03 10:01       ` Thomas Graf
2012-04-03 10:17         ` Bruno Prémont

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