From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [patch net-next-2.6 1/2] net: allow to change carrier via sysfs Date: Wed, 31 Aug 2011 21:44:40 +0100 Message-ID: <1314823481.3274.26.camel@bwh-desktop> References: <1314715608-978-1-git-send-email-jpirko@redhat.com> <1314715608-978-2-git-send-email-jpirko@redhat.com> <20110831082655.GB2010@minipsycho.brq.redhat.com> <20110831084511.GD2010@minipsycho.brq.redhat.com> <4E5E939C.5000009@gmail.com> <1314821537.3274.24.camel@bwh-desktop> <4E5E9A30.1040105@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jiri Pirko , =?UTF-8?Q?Micha=C5=82_Miros=C5=82aw?= , netdev@vger.kernel.org, davem@davemloft.net, eric.dumazet@gmail.com, shemminger@vyatta.com To: Nicolas de =?ISO-8859-1?Q?Peslo=FCan?= Return-path: Received: from exchange.solarflare.com ([216.237.3.220]:3926 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752077Ab1HaUoo convert rfc822-to-8bit (ORCPT ); Wed, 31 Aug 2011 16:44:44 -0400 In-Reply-To: <4E5E9A30.1040105@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2011-08-31 at 22:31 +0200, Nicolas de Peslo=C3=BCan wrote: > Le 31/08/2011 22:12, Ben Hutchings a =C3=A9crit : > > On Wed, 2011-08-31 at 22:03 +0200, Nicolas de Peslo=C3=BCan wrote: > >> Le 31/08/2011 10:45, Jiri Pirko a =C3=A9crit : > >> > >>>>>> Do you expect drivers using implementation different than just= calling > >>>>>> netif_carrier_on/off? Or is it supposed to also e.g. power dow= n PHYs? > >>>>> Yes, generally it can be used also for en/disable phy, for test= ing > >>>>> purposes if hw and driver would support it. > >>>> > >>>> I'd like to see this working for GRE tunnel devices (for keepali= ve > >>>> daemon to be able to indicate to routing daemons whether tunnel = is > >>>> really working) - implementation would be identical to dummy's c= ase. > >>>> Should I prepare a patch or can I leave it to you? > >>> > >>> Ok, I can include it to this patchset (I'm going to repost first = patch > >>> anyway) > >> > >> Can't we assume that the dummy's case is the default behavior and > >> register this default > >> ndo_change_carrier callback for every device ? > > > > You have got to be joking. No device driver that has real link > > monitoring should use this implementation. >=20 > Well, why not? Arguably, this is probably not the feature one would > use every day, but... >=20 > Testing a cluster reaction to a link down event would be easier if on= e > doesn't need to unplug the=20 > cable for the test. I understand that one can turn off the switch por= t > (physical or virtual), but=20 > echo 0 > /sys/class/net/eth0/carrier would be nice too. >=20 > Of course, I assume that netif_carrier_on and netif_carrier_off are > only called on real link status=20 > change. So the value written into /sys/class/net/eth0/carrier would > stay until the link revert it,=20 > due to a double status change (up-down-up or down-up-down). But I may > miss totally this point. Think what happens if the user sets carrier on, when the link is actually down. Ben. --=20 Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.