From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F28AC43381 for ; Wed, 27 Mar 2019 13:25:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3707921738 for ; Wed, 27 Mar 2019 13:25:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729808AbfC0NZn (ORCPT ); Wed, 27 Mar 2019 09:25:43 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:37656 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725797AbfC0NZn (ORCPT ); Wed, 27 Mar 2019 09:25:43 -0400 Received: by mail-qk1-f195.google.com with SMTP id c1so9848738qkk.4 for ; Wed, 27 Mar 2019 06:25:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=JadBfZKBm3e9Mygp+PZqyYjMXkZxEZrMEJvF9oBgpnI=; b=tMl8nWVoLaU9BBw2F7b/uLaxJbQ3VbChhU7UW49y7vKiswj+Yx2F8aVVvDEdyuIfHD CAf0rkuesxprh3e03t0XB1d9v5MGQUGrsruY3H1zE0zHNZSh4t7veiUSkeK9+5YzG834 4SCBBfMDI/mFWPek4rS8VV935jf9oC9pV6prP/MN+yb2ZdaGia9BawXB+f85YNGqswpR twPQrxswYcyGyz4/cOA1XR+cB2UQU5jQhXj4vyx7h9Zut1il+UNXbaLMqjGqfXsbDPMD DPT550JCNqcr46BL7cPa47VUNVv9i0g8o9YS9lBdqmuepfPe5KvAH+9UUTBzNY8LOmc9 w2/Q== X-Gm-Message-State: APjAAAUS3JC3qddZaBXZWQjTSi8PWJhcJKxEhGrXfXniUNhiMT0KGeP3 JCZHai+NYYfMpiEExaoiGw3DnA== X-Google-Smtp-Source: APXvYqymhgoVMw3si4dUjfIC+i1XHhU0eTXT9W6KHQr6j5UEY6l+3ok+XN8EUf7YUMcKY7fog2jJ4g== X-Received: by 2002:a05:620a:11:: with SMTP id j17mr29926155qki.111.1553693142734; Wed, 27 Mar 2019 06:25:42 -0700 (PDT) Received: from redhat.com (pool-173-76-246-42.bstnma.fios.verizon.net. [173.76.246.42]) by smtp.gmail.com with ESMTPSA id r53sm3014733qtr.80.2019.03.27.06.25.40 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 27 Mar 2019 06:25:41 -0700 (PDT) Date: Wed, 27 Mar 2019 09:25:39 -0400 From: "Michael S. Tsirkin" To: Stephen Hemminger Cc: Si-Wei Liu , sridhar.samudrala@intel.com, davem@davemloft.net, kubakici@wp.pl, alexander.duyck@gmail.com, jiri@resnulli.us, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, liran.alon@oracle.com, boris.ostrovsky@oracle.com, vijay.balakrishna@oracle.com Subject: Re: [PATCH net v3] failover: allow name change on IFF_UP slave interfaces Message-ID: <20190327092424-mutt-send-email-mst@kernel.org> References: <1553644093-10917-1-git-send-email-si-wei.liu@oracle.com> <20190326191342.11f0cb55@shemminger-XPS-13-9360> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190326191342.11f0cb55@shemminger-XPS-13-9360> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Mar 26, 2019 at 07:13:42PM -0700, Stephen Hemminger wrote: > On Tue, 26 Mar 2019 19:48:13 -0400 > Si-Wei Liu wrote: > > > When a netdev appears through hot plug then gets enslaved by a failover > > master that is already up and running, the slave will be opened > > right away after getting enslaved. Today there's a race that userspace > > (udev) may fail to rename the slave if the kernel (net_failover) > > opens the slave earlier than when the userspace rename happens. > > Unlike bond or team, the primary slave of failover can't be renamed by > > userspace ahead of time, since the kernel initiated auto-enslavement is > > unable to, or rather, is never meant to be synchronized with the rename > > request from userspace. > > > > As the failover slave interfaces are not designed to be operated > > directly by userspace apps: IP configuration, filter rules with > > regard to network traffic passing and etc., should all be done on master > > interface. In general, userspace apps only care about the > > name of master interface, while slave names are less important as long > > as admin users can see reliable names that may carry > > other information describing the netdev. For e.g., they can infer that > > "ens3nsby" is a standby slave of "ens3", while for a > > name like "eth0" they can't tell which master it belongs to. > > > > Historically the name of IFF_UP interface can't be changed because > > there might be admin script or management software that is already > > relying on such behavior and assumes that the slave name can't be > > changed once UP. But failover is special: with the in-kernel > > auto-enslavement mechanism, the userspace expectation for device > > enumeration and bring-up order is already broken. Previously initramfs > > and various userspace config tools were modified to bypass failover > > slaves because of auto-enslavement and duplicate MAC address. Similarly, > > in case that users care about seeing reliable slave name, the new type > > of failover slaves needs to be taken care of specifically in userspace > > anyway. > > > > It's less risky to lift up the rename restriction on failover slave > > which is already UP. Although it's possible this change may potentially > > break userspace component (most likely configuration scripts or > > management software) that assumes slave name can't be changed while > > UP, it's relatively a limited and controllable set among all userspace > > components, which can be fixed specifically to listen for the rename > > and/or link down/up events on failover slaves. Userspace component > > interacting with slaves is expected to be changed to operate on failover > > master interface instead, as the failover slave is dynamic in nature > > which may come and go at any point. The goal is to make the role of > > failover slaves less relevant, and userspace components should only > > deal with failover master in the long run. > > > > Fixes: 30c8bd5aa8b2 ("net: Introduce generic failover module") > > Signed-off-by: Si-Wei Liu > > Reviewed-by: Liran Alon > > > Why do you need to do dev_close/dev_open which will bounce > the link? What we need is notify userspace that link went up/down. close/open will do that but just sending notifications would do that as well without playing with link states. -- MST