netdev - Re: [net-next PATCH 0/3] qdisc and tx_queue_len cleanups for IFF_NO

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Date:   Mon, 7 Nov 2016 21:11:17 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, phil@....cc, robert@...julf.se,
        jhs@...atatu.com, brouer@...hat.com
Subject: Re: [net-next PATCH 0/3] qdisc and tx_queue_len cleanups for
 IFF_NO_QUEUE devices

On Mon, 07 Nov 2016 13:13:44 -0500 (EST)
David Miller <davem@...emloft.net> wrote:

> From: Jesper Dangaard Brouer <brouer@...hat.com>
> Date: Thu, 03 Nov 2016 14:55:56 +0100
> 
> > This patchset is a cleanup for IFF_NO_QUEUE devices.  It will
> > hopefully help userspace get a more consistent behavior when attaching
> > qdisc to such virtual devices.  
> 
> I'm still thinking about this.
> 
> My reservation about this is basically since the one known offender in
> userspace acknowledged that what it was doing wrong, and fixed it
> quickly already, I see no reason to explicitly accomodate this.

The situation I worry about is that a sysadm cannot manually apply a tc
qdisc on a Docker container's veth without getting bitten.  Docker will
forever run a "loophole-script" to accommodate older kernels, and yes
the shiny management scripts will get fixed, but how should a mortal
sysadm know (to change tx_queue_len before applying a qdisc).

Besides the it was only fixed in OpenShift, which inherited the "bug"
from Docker.  Thus, it is per-say not fixed in Docker or other projects
that (like OpenShift) uses components from Docker.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer