From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vitaly Kuznetsov Subject: Re: [PATCH net-next 0/1] netvsc: another VF datapath fix Date: Tue, 08 Aug 2017 17:24:03 +0200 Message-ID: <87shh29j70.fsf@vitty.brq.redhat.com> References: <20170807183000.10827-1-sthemmin@microsoft.com> <87ziba9mwj.fsf@vitty.brq.redhat.com> <20170808081506.38bea86c@xeon-e3> Mime-Version: 1.0 Content-Type: text/plain Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, devel@linuxdriverproject.org, netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58226 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752017AbdHHPYG (ORCPT ); Tue, 8 Aug 2017 11:24:06 -0400 In-Reply-To: <20170808081506.38bea86c@xeon-e3> (Stephen Hemminger's message of "Tue, 8 Aug 2017 08:15:06 -0700") Sender: netdev-owner@vger.kernel.org List-ID: Stephen Hemminger writes: > On Tue, 08 Aug 2017 16:03:56 +0200 > Vitaly Kuznetsov wrote: > >> Stephen Hemminger writes: >> >> > Previous fix was incomplete. >> > >> >> Not really related to this patch series (which btw fixes my issue, >> thanks!), but I found one addition issue. Systemd fails to rename VF >> interface: >> >> kernel: mlx4_core 0002:00:02.0 eth2: joined to eth1 >> kernel: hv_netvsc 33b7a6f9-6736-451f-8fce-b382eaa50bee eth1: VF registering: eth2 >> kernel: hv_netvsc 33b7a6f9-6736-451f-8fce-b382eaa50bee eth1: Data path switched to VF: eth2 >> kernel: mlx4_en: eth2: Link Up >> NetworkManager[750]: [1502200557.0821] device (eth2): link connected >> NetworkManager[750]: [1502200557.1004] manager: (eth2): new Ethernet device (/org/freedesktop/NetworkManager/Devices/6) >> systemd-udevd[6942]: Error changing net interface name 'eth2' to 'enP2p0s2': Device or resource busy >> systemd-udevd[6942]: could not rename interface '6' from 'eth2' to 'enP2p0s2': Device or resource busy >> >> With some debug added I figured out what's wrong: __netvsc_vf_setup() >> does dev_open() which sets IFF_UP flag on the interface. When systemd >> tries to rename the interface we get into dev_change_name() and this >> fails with -EBUSY when (dev->flags & IFF_UP). >> >> The issue is of less importance as we're not supposed to configure VF >> interface now. However, we may still want to get a stable name for it. >> >> Any idea how this can be fixed? > > The problem is Network Manager should ignore the VF device. I don't run NM on these > interfaces because it causes more issues than it helps (dueling userspace). > > The driver needs to have slave track the master interface. Relying on userspace > to bring interface up leads to all the issues the bonding script had. > > One option would be to delay the work of bringing up the slave device to allow > small window for renaming to run. Actually, I tried removing 'if (dev->flags & IFF_UP)' check from dev_change_name() and everything seems to work fine. The history of this code predates git so I have no idea why it's forbiden to change names of IFF_UP interfaces... I can send an RFC removing the check to figure out the truth :-) -- Vitaly