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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, 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 D5982C43381 for ; Thu, 28 Mar 2019 20:15:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 930DF2173C for ; Thu, 28 Mar 2019 20:15:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="kOj8twPW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726318AbfC1UPl (ORCPT ); Thu, 28 Mar 2019 16:15:41 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:45380 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726165AbfC1UPl (ORCPT ); Thu, 28 Mar 2019 16:15:41 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2SK8qix170844; Thu, 28 Mar 2019 20:15:25 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : references : cc : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=/O34zCm4aFZhOnGrMOwAcb/ltkZtCf5dwNTUmWZY9Mw=; b=kOj8twPWwq2lsDa5wpgQNK2LTqIvB3/0AYEacfNgWcamxdGE2s01zEG62+PL91U59Iz+ 0f2nN/lEDrUSkqlxy3bF/PETB+Eq8Xc7D2fWKAqFrclVOO4JaYaORjUziZXGmBoOi8Xd RlpIld3913AWBEo1reVrxmQMjsC6ZpZ160evEI1hJ4W/Xg9OTUwEJSDF3dvEJBrU3oUW Nl0unWCOkdqrxvlyl1f8vQZD7HUnhCpxiBSUkZSRxuUg1GiEnJHiJu7iuHAbdxC0CAYi KdjP6760H54TSBm8wgpQ71jidMT/HmvaX0idncPNgjDxsZQjWwjAIZRaL22qrvbzKzeQ yg== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2120.oracle.com with ESMTP id 2re6djrxwu-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 20:15:24 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x2SKFN4h001043 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 20:15:24 GMT Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x2SKFMpZ001714; Thu, 28 Mar 2019 20:15:22 GMT Received: from [10.159.139.204] (/10.159.139.204) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 28 Mar 2019 13:15:22 -0700 Subject: Re: [PATCH net v3] failover: allow name change on IFF_UP slave interfaces To: Stephen Hemminger References: <1553644093-10917-1-git-send-email-si-wei.liu@oracle.com> <20190327111132.GI6979@nanopsycho> <06fa1aec-d9a6-3ca7-8849-a1656349ab83@oracle.com> <20190328101426.25bf5316@shemminger-XPS-13-9360> Cc: Jiri Pirko , mst@redhat.com, sridhar.samudrala@intel.com, davem@davemloft.net, kubakici@wp.pl, alexander.duyck@gmail.com, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, liran.alon@oracle.com, boris.ostrovsky@oracle.com, vijay.balakrishna@oracle.com From: si-wei liu Organization: Oracle Corporation Message-ID: <8048eec5-4573-f8e4-1bc8-1c78b330f330@oracle.com> Date: Thu, 28 Mar 2019 13:15:15 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20190328101426.25bf5316@shemminger-XPS-13-9360> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9209 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903280131 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 3/28/2019 10:14 AM, Stephen Hemminger wrote: > On Wed, 27 Mar 2019 16:44:19 -0700 > si-wei liu wrote: > >> On 3/27/2019 4:11 AM, Jiri Pirko wrote: >>> Wed, Mar 27, 2019 at 12:48:13AM CET, si-wei.liu@oracle.com 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 >>>> >>>> -- >>>> v1 -> v2: >>>> - Drop configurable module parameter (Sridhar) >>>> >>>> v2 -> v3: >>>> - Drop additional IFF_SLAVE_RENAME_OK flag (Sridhar) >>>> - Send down and up events around rename (Michael S. Tsirkin) >>>> --- >>>> net/core/dev.c | 37 ++++++++++++++++++++++++++++++++++--- >>>> 1 file changed, 34 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/net/core/dev.c b/net/core/dev.c >>>> index 722d50d..3e0cd80 100644 >>>> --- a/net/core/dev.c >>>> +++ b/net/core/dev.c >>>> @@ -1171,6 +1171,7 @@ int dev_get_valid_name(struct net *net, struct net_device *dev, >>>> int dev_change_name(struct net_device *dev, const char *newname) >>>> { >>>> unsigned char old_assign_type; >>>> + bool reopen_needed = false; >>>> char oldname[IFNAMSIZ]; >>>> int err = 0; >>>> int ret; >>>> @@ -1180,8 +1181,24 @@ int dev_change_name(struct net_device *dev, const char *newname) >>>> BUG_ON(!dev_net(dev)); >>>> >>>> net = dev_net(dev); >>>> - if (dev->flags & IFF_UP) >>>> - return -EBUSY; >>>> + >>>> + /* Allow failover slave to rename even when >>>> + * it is up and running. >>>> + * >>>> + * Failover slaves are special, since userspace >>>> + * might rename the slave after the interface >>>> + * has been brought up and running due to >>>> + * auto-enslavement. >>>> + * >>>> + * Failover users don't actually care about slave >>>> + * name change, as they are only expected to operate >>>> + * on master interface directly. >>>> + */ >>>> + if (dev->flags & IFF_UP) { >>>> + if (likely(!(dev->priv_flags & IFF_FAILOVER_SLAVE))) >>>> + return -EBUSY; >>>> + reopen_needed = true; >>>> + } >>>> >>>> write_seqcount_begin(&devnet_rename_seq); >>>> >>>> @@ -1198,6 +1215,9 @@ int dev_change_name(struct net_device *dev, const char *newname) >>>> return err; >>>> } >>>> >>>> + if (reopen_needed) >>>> + dev_close(dev); >>> Ugh. Don't dev_close/dev_open on name change. >> See my response to Michael and Stephen. What's your suggestion then? > To a DEV_CHANGE notification instead? Thanks. That is what I was thinking. Will post a v4 to simplify the notification. Not worth the effort to fine tune for cases in hypothesis. -Siwei > > > My opinion is that allowing name change is not worth the doing. > Also, the kernel should never do the name change, it is up to userspace. >