From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yanko Kaneti Subject: Re: PPPOE lockdep report in dev_queue_xmit+0x8b8/0x900 Date: Tue, 19 Feb 2013 13:10:21 +0200 Message-ID: <1361272221.2282.5.camel@d2> References: <1361209421.9147.12.camel@d2> <1361217052.19353.101.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from indigo.declera.com ([212.116.131.21]:40204 "HELO indigo.declera.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932354Ab3BSLKi (ORCPT ); Tue, 19 Feb 2013 06:10:38 -0500 In-Reply-To: <1361217052.19353.101.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2013-02-18 at 11:50 -0800, Eric Dumazet wrote: > From: Eric Dumazet > > On Mon, 2013-02-18 at 19:43 +0200, Yanko Kaneti wrote: > > Hello, > > > > I've had the following lockdep report for the last couple of years of > > kernels. I don't think I've had a lockup during that time related to > > pppoe. > > > > The pppoe entry in the MAINTAINERS file lists Michal Ostrowski > > which unfortunately bounces. > > > > Thanks for the report. > > Could you please test following patch ? It looks like it has done the job. I am running a kernel with the patch and workload that otherwise inevitably triggers the splat and so far it has been quiet. Thanks > > [PATCH] ppp: set qdisc_tx_busylock to avoid LOCKDEP splat > > If a qdisc is installed on a ppp device, its possible to get > a lockdep splat under stress, because nested dev_queue_xmit() can > lock busylock a second time (on a different device, so its a false > positive) > > Avoid this problem using a distinct lock_class_key for team > devices. > > Reported-by: Yanko Kaneti > Signed-off-by: Eric Dumazet > --- > drivers/net/ppp/ppp_generic.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c > index 4fd754e..3db9131 100644 > --- a/drivers/net/ppp/ppp_generic.c > +++ b/drivers/net/ppp/ppp_generic.c > @@ -1058,7 +1058,15 @@ ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64) > return stats64; > } > > +static struct lock_class_key ppp_tx_busylock; > +static int ppp_dev_init(struct net_device *dev) > +{ > + dev->qdisc_tx_busylock = &ppp_tx_busylock; > + return 0; > +} > + > static const struct net_device_ops ppp_netdev_ops = { > + .ndo_init = ppp_dev_init, > .ndo_start_xmit = ppp_start_xmit, > .ndo_do_ioctl = ppp_net_ioctl, > .ndo_get_stats64 = ppp_get_stats64, > > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html