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 A0E69C43381 for ; Fri, 29 Mar 2019 19:50:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E3C1218A5 for ; Fri, 29 Mar 2019 19:50:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="cX2MYLBl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729982AbfC2Tuw (ORCPT ); Fri, 29 Mar 2019 15:50:52 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:56046 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729906AbfC2Tuv (ORCPT ); Fri, 29 Mar 2019 15:50:51 -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 x2TJnJQM109595; Fri, 29 Mar 2019 19:50:37 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=2OPKktzUa9RM4dIxAEuIZRoqS4WRR1XsEXEpy62Ah6o=; b=cX2MYLBlHby6n2bgS+VkCzAifeup8KHWN2EKMS90KDLXFmqhNJrFb9DjtT4440Ir3gf0 6fbHbb7UlG/XIRsP0QWL0UGK28fnx98Z1nymClp3JjIE9P6doouNA1/T5VVjotdO5nCf tcftkjiHJuuKSpqOmMD73TY7pBZIt0YJE/IgTTmXXBfsJyzg/0X8fGBKCP0kQ7oEoeG6 RqRQCYPH09zrR72To9fqespD9Ve8Hhs95cy5ZAdaIJxOQNKnLWu85cb05h/2KYM1+NGp JBfRsMMqQuw7B5dUtmP71HLeny//WbAoaX+5iMCBryqbNVzFulV+fVKoyeKA4JcSjTGT YQ== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2120.oracle.com with ESMTP id 2re6djxg51-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 29 Mar 2019 19:50:37 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x2TJoa2L010898 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 29 Mar 2019 19:50:36 GMT Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x2TJoWhh006058; Fri, 29 Mar 2019 19:50:32 GMT Received: from [10.159.154.152] (/10.159.154.152) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 29 Mar 2019 12:50:32 -0700 Subject: Re: [PATCH net v4] failover: allow name change on IFF_UP slave interfaces To: "Samudrala, Sridhar" , mst@redhat.com, stephen@networkplumber.org, davem@davemloft.net, kubakici@wp.pl, alexander.duyck@gmail.com, jiri@resnulli.us, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org References: <1553816847-28121-1-git-send-email-si-wei.liu@oracle.com> <983b8634-b39a-7942-70a5-8f3dc5720997@intel.com> Cc: liran.alon@oracle.com, boris.ostrovsky@oracle.com, vijay.balakrishna@oracle.com From: si-wei liu Organization: Oracle Corporation Message-ID: Date: Fri, 29 Mar 2019 12:50:25 -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: <983b8634-b39a-7942-70a5-8f3dc5720997@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9211 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=4 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-1903290136 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 3/28/2019 10:55 PM, Samudrala, Sridhar wrote: > > > On 3/28/2019 4:47 PM, 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 >> >> -- >> 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) >> >> v3 -> v4: >> - Simplify notification to be sent (Stephen Hemminger) >> --- >> net/core/dev.c | 24 +++++++++++++++++++++++- >> 1 file changed, 23 insertions(+), 1 deletion(-) >> >> diff --git a/net/core/dev.c b/net/core/dev.c >> index 722d50d..6ae5874 100644 >> --- a/net/core/dev.c >> +++ b/net/core/dev.c >> @@ -1180,7 +1180,21 @@ 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) >> + >> + /* 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 && >> + likely(!(dev->priv_flags & IFF_FAILOVER_SLAVE))) >> return -EBUSY; >> write_seqcount_begin(&devnet_rename_seq); >> @@ -1227,6 +1241,14 @@ int dev_change_name(struct net_device *dev, >> const char *newname) >> hlist_add_head_rcu(&dev->name_hlist, dev_name_hash(net, >> dev->name)); >> write_unlock_bh(&dev_base_lock); >> + if (unlikely(dev->flags & IFF_UP)) { >> + struct netdev_notifier_change_info change_info; >> + >> + change_info.flags_changed = 0; >> + call_netdevice_notifiers_info(NETDEV_CHANGE, dev, >> + &change_info.info); > > This function no longer takes the dev parameter in the net-next kernel. OK. Will get my patch updated with the latest net-next tree. > > Did you consider calling netdev_state_change() although it does send a > RTM_NEWLINK message too. May be just fixing the notifier call should > be fine. I did look at it and the extra RTM_NEWLINK message was indeed the reason I got it rewritten. You see, how the way of initialization is inherited. Thanks, -Siwei > >> + } >> + >> ret = call_netdevice_notifiers(NETDEV_CHANGENAME, dev); >> ret = notifier_to_errno(ret); >>