From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yuval Shaia Subject: Re: [PATCH] Add support for netconsole driver used on bridge device with VIF attached Date: Mon, 29 Apr 2013 13:42:25 +0300 Message-ID: <1367232145.26060.1.camel@yuval-pc> References: <5757e54b-902b-4338-8ac9-43857cd1906c@default> <50FD8243.6000501@oracle.com> <1358846612.3279.282.camel@zakaz.uk.xensource.com> <201301291054.46405.yuval.shaia@oracle.com> <1359455385.12252.85.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "xen-devel@lists.xensource.com" , "netdev@vger.kernel.org" , bridge@lists.linux-foundation.org, Stephen Hemminger To: Ian Campbell Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:43992 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751946Ab3D2Kmh (ORCPT ); Mon, 29 Apr 2013 06:42:37 -0400 In-Reply-To: <1359455385.12252.85.camel@zakaz.uk.xensource.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2013-01-29 at 10:29 +0000, Ian Campbell wrote: > On Tue, 2013-01-29 at 08:54 +0000, Yuval Shaia wrote: > > > Please can you explain the exact code path which results in this new > > > hook being called. > > > > > init_netconsole() in netconsole.c -> alloc_param_target() -> netpoll_setup() > > in netpoll.c -> __netpoll_setup() which check if ndo_poll_controller() > > operation is supported. > > Are you sure this is being called for the VIF interface? In your > configuration I'd expect it to be called on the bridge not the vif, or > at least for calling on the VIF to not impact whether netpool was > enabled for the bridge or not. > > I think the underlying issue which you are seeing is that > br_netpoll_setup() requires that all members of the bridge support > netpoll before allowing netpoll to be enabled on the bridge itself. > > This seems like an odd restriction in the bridge driver since in > principal only the port over which the netpoll traffic will be going > will need netpoll, but perhaps the bridge can't tell which port that is > or is going to be? I think it is worth discussing this with the bridge > maintainers (who I have CC'd, threads starts at > http://marc.info/?l=linux-netdev&m=135878868112700&w=2) > > Hopefully the bridge isn't flooding/broadcasting netpoll to all ports, > at least in the case where DST IP and MAC have been specified. That > would be rather inefficient, especially when most ports go to virtual > machines. > > So before I ack this patch I'd like to hear back from the bridge > maintainers about whether the current behaviour in the bridge is > intended and whether it could be fixed in some better way than adding > netpoll to netback. Ian, Can you suggest how to continue from here? as i don't see any comment on that issue up to now. Yuval > > AFAICT the only reason to actually support netpoll in netback would be > if you wanted host logs to go to a listener running in a domain on the > same host, which sounds like a mad idea to me! If someone actually has a > real need for that use case and can test that it works I'd be happy to > reconsider this patch on that basis (assuming the necessary #ifdefs are > added as mentioned before). > > > > BTW looking at the patch as it is any use of this hook should be wrapped > > > in CONFIG_NET_POLL_CONTROLLER. > > > > > > Ian. > > > > > > > > >