From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Sutter Subject: Re: [net-next PATCH 3/3] qdisc: catch misconfig of attaching qdisc to tx_queue_len zero device Date: Fri, 4 Nov 2016 10:35:26 +0100 Message-ID: <20161104093526.GM5640@orbyte.nwl.cc> References: <20161103135534.28737.37657.stgit@firesoul> <20161103135611.28737.39840.stgit@firesoul> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, Robert Olsson , Jamal Hadi Salim To: Jesper Dangaard Brouer Return-path: Received: from orbyte.nwl.cc ([151.80.46.58]:53423 "EHLO mail.nwl.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752736AbcKDJf2 (ORCPT ); Fri, 4 Nov 2016 05:35:28 -0400 Content-Disposition: inline In-Reply-To: <20161103135611.28737.39840.stgit@firesoul> Sender: netdev-owner@vger.kernel.org List-ID: Hi, On Thu, Nov 03, 2016 at 02:56:11PM +0100, Jesper Dangaard Brouer wrote: [...] > diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c > index 206dc24add3a..f337f1bdd1d4 100644 > --- a/net/sched/sch_api.c > +++ b/net/sched/sch_api.c > @@ -960,6 +960,17 @@ static struct Qdisc *qdisc_create(struct net_device *dev, > > sch->handle = handle; > > + /* This exist to keep backward compatible with a userspace > + * loophole, what allowed userspace to get IFF_NO_QUEUE > + * facility on older kernels by setting tx_queue_len=0 (prior > + * to qdisc init), and then forgot to reinit tx_queue_len > + * before again attaching a qdisc. > + */ > + if ((dev->priv_flags & IFF_NO_QUEUE) && (dev->tx_queue_len == 0)) { > + dev->tx_queue_len = DEFAULT_TX_QUEUE_LEN; > + netdev_info(dev, "Caught tx_queue_len zero misconfig\n"); > + } I wonder why this is limited to IFF_NO_QUEUE devices. Do you think there is a valid use case for physical ones? Also, if we sanitize here, couldn't we then just get rid of the sanitization you're fixing in patch 2? Apart from that, ACK to all the patches. Thanks for cleaning up my mess! :) Cheers, Phil