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=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 BADA3C43381 for ; Wed, 27 Mar 2019 23:44:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8226E2075E for ; Wed, 27 Mar 2019 23:44:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="rxXLkz3l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732867AbfC0Xop (ORCPT ); Wed, 27 Mar 2019 19:44:45 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:57554 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731676AbfC0Xoo (ORCPT ); Wed, 27 Mar 2019 19:44:44 -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 x2RNi88D155586; Wed, 27 Mar 2019 23:44:29 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=CDqjtWirWijraiRpIO+dZkY7lbikRHMf7pn/qblHzX8=; b=rxXLkz3lVYPeBK1AWjbAVYvPJVxPjTh+gt4GVZMsHEJjQN0OBJA853bsFPhknV4Kt0Yr gnM/0VoMG/0M14jG1vMfanQNVhVceae5oulYO5M70gXRN2mTK+YPWM1gWp9gj7Xry8D5 APrn9KHmSC2qsicCbiYnGv4gR7TbbOJz0GZAnZ+PNCb3tAvLcbDgInM3geytR1Fun1zH n8VcW46ra6Mu8vd5/uvPzfwM2q4UqVnsDnVxU12eAGYOwzsnzCj3jd/7fWFd4LiEhoq7 WRW/rW+5qm70wUIPtZ23PBFReKm7hA+4VnHwReBS6DIMovcuFWG7rByfgHEQUiM9E8dZ 1A== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2120.oracle.com with ESMTP id 2re6djkmk1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Mar 2019 23:44:28 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x2RNiRix018649 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 27 Mar 2019 23:44:27 GMT Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x2RNiQri029634; Wed, 27 Mar 2019 23:44:26 GMT Received: from [10.159.236.24] (/10.159.236.24) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 27 Mar 2019 16:44:26 -0700 Subject: Re: [PATCH net v3] failover: allow name change on IFF_UP slave interfaces To: Jiri Pirko References: <1553644093-10917-1-git-send-email-si-wei.liu@oracle.com> <20190327111132.GI6979@nanopsycho> Cc: mst@redhat.com, sridhar.samudrala@intel.com, stephen@networkplumber.org, 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: <06fa1aec-d9a6-3ca7-8849-a1656349ab83@oracle.com> Date: Wed, 27 Mar 2019 16:44:19 -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: <20190327111132.GI6979@nanopsycho> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9208 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-1903270163 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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? > >> + >> if (oldname[0] && !strchr(oldname, '%')) >> netdev_info(dev, "renamed from %s\n", oldname); >> >> @@ -1210,7 +1230,9 @@ int dev_change_name(struct net_device *dev, const char *newname) >> memcpy(dev->name, oldname, IFNAMSIZ); >> dev->name_assign_type = old_assign_type; >> write_seqcount_end(&devnet_rename_seq); >> - return ret; >> + if (err >= 0) >> + err = ret; >> + goto reopen; >> } >> >> write_seqcount_end(&devnet_rename_seq); >> @@ -1246,6 +1268,15 @@ int dev_change_name(struct net_device *dev, const char *newname) >> } >> } >> >> +reopen: >> + if (reopen_needed) { >> + ret = dev_open(dev); >> + if (ret) { >> + pr_err("%s: reopen device failed: %d\n", >> + dev->name, ret); >> + } >> + } >> + >> return err; >> } >> >> -- >> 1.8.3.1 >>