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=-6.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,T_DKIM_INVALID,URIBL_BLOCKED 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 DD662C433F4 for ; Mon, 24 Sep 2018 07:06:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6169221486 for ; Mon, 24 Sep 2018 07:06:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="kLhQZO/7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6169221486 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727603AbeIXNGh (ORCPT ); Mon, 24 Sep 2018 09:06:37 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:40496 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725858AbeIXNGh (ORCPT ); Mon, 24 Sep 2018 09:06:37 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w8O6wR3X145098; Mon, 24 Sep 2018 07:05:51 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=mime-version : message-id : date : from : sender : to : cc : subject : references : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=hu/tLYo0LMOkNLgYxXaGWbvGt42mbnJRXKKG4yTehuQ=; b=kLhQZO/74bz95yP12ZmwPPHx/Pr+DntOcgIdjJoUW3nmbsqsqxjnK+8sOAiN/ICVQbDK +I099bMaWRk/Du53bkDmJBx50Ufa6gGpSvTlqn9vlsRMrb8Jp44Xa+qrIXl9DEl2vE7L cRVZMcVeUE2DpmeIs6T8TclcHnKU4sI7pFMBYzR72OTnZKK7pN3gAdz+VR0kJ2DNhHb6 s4GJy/PhMe9D4b1O+Pb9ZA3c2FPI6BIOG420+Td5wC8mcMUdAJM8lU69RuqgeKgWq+AT 2V/z5WadLCS4Lf3L2ECsy+Hsm2lhCI1yCmtROGct+nkIS0ZrXObUurl2OG8L2kU1bU42 ag== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp2120.oracle.com with ESMTP id 2mndpp3wk1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 24 Sep 2018 07:05:51 +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 w8O75j69030337 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 24 Sep 2018 07:05:45 GMT Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w8O75i6M031677; Mon, 24 Sep 2018 07:05:44 GMT MIME-Version: 1.0 Message-ID: Date: Mon, 24 Sep 2018 00:05:42 -0700 (PDT) From: Manish Kumar Singh To: Eric Dumazet , netdev@vger.kernel.org Cc: Jay Vosburgh , Veaceslav Falico , Andy Gospodarek , "David S. Miller" , linux-kernel@vger.kernel.org Subject: RE: [PATCH] bonding: avoid repeated display of same link status change References: <20180917072059.32657-1-mk.singh@oracle.com> <33a66a80-22ed-d6b3-f6b2-4463357c5ffa@gmail.com> <78bf3185-fbd1-4a6c-ae32-70da0af2cbb4@default> <05f57c08-3ebb-7ee5-7ab2-519cb5a70bd8@gmail.com> In-Reply-To: <05f57c08-3ebb-7ee5-7ab2-519cb5a70bd8@gmail.com> X-Priority: 3 X-Mailer: Oracle Beehive Extensions for Outlook 2.0.1.9.1 (1003210) [OL 14.0.7212.0 (x86)] Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9025 signatures=668707 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809240076 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Eric Dumazet [mailto:eric.dumazet@gmail.com] > Sent: 18 =E0=A4=B8=E0=A4=BF=E0=A4=A4=E0=A4=AE=E0=A5=8D=E0=A4=AC=E0=A4=B0 = 2018 19:30 > To: Manish Kumar Singh; Eric Dumazet; netdev@vger.kernel.org > Cc: Jay Vosburgh; Veaceslav Falico; Andy Gospodarek; David S. Miller; lin= ux- > kernel@vger.kernel.org > Subject: Re: [PATCH] bonding: avoid repeated display of same link status > change >=20 >=20 >=20 > On 09/17/2018 10:05 PM, Manish Kumar Singh wrote: > > > > > >> -----Original Message----- > >> From: Eric Dumazet [mailto:eric.dumazet@gmail.com] > >> Sent: 17 =E0=A4=B8=E0=A4=BF=E0=A4=A4=E0=A4=AE=E0=A5=8D=E0=A4=AC=E0=A4= =B0 2018 20:08 > >> To: Manish Kumar Singh; netdev@vger.kernel.org > >> Cc: Jay Vosburgh; Veaceslav Falico; Andy Gospodarek; David S. Miller; > linux- > >> kernel@vger.kernel.org > >> Subject: Re: [PATCH] bonding: avoid repeated display of same link stat= us > >> change > >> > >> > >> > >> On 09/17/2018 12:20 AM, mk.singh@oracle.com wrote: > >>> From: Manish Kumar Singh > >>> > >>> When link status change needs to be committed and rtnl lock couldn't = be > >>> taken, avoid redisplay of same link status change message. > >>> > >>> Signed-off-by: Manish Kumar Singh > >>> --- > >>> drivers/net/bonding/bond_main.c | 6 ++++-- > >>> include/net/bonding.h | 1 + > >>> 2 files changed, 5 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/drivers/net/bonding/bond_main.c > >> b/drivers/net/bonding/bond_main.c > >>> index 217b790d22ed..fb4e3aff1677 100644 > >>> --- a/drivers/net/bonding/bond_main.c > >>> +++ b/drivers/net/bonding/bond_main.c > >>> @@ -2087,7 +2087,7 @@ static int bond_miimon_inspect(struct bonding > >> *bond) > >>> =09=09=09bond_propose_link_state(slave, BOND_LINK_FAIL); > >>> =09=09=09commit++; > >>> =09=09=09slave->delay =3D bond->params.downdelay; > >>> -=09=09=09if (slave->delay) { > >>> +=09=09=09if (slave->delay && !bond->rtnl_needed) { > >>> =09=09=09=09netdev_info(bond->dev, "link status down > for > >> %sinterface %s, disabling it in %d ms\n", > >>> =09=09=09=09=09 (BOND_MODE(bond) =3D=3D > >>> =09=09=09=09=09 BOND_MODE_ACTIVEBACKUP) ? > >>> @@ -2127,7 +2127,7 @@ static int bond_miimon_inspect(struct bonding > >> *bond) > >>> =09=09=09commit++; > >>> =09=09=09slave->delay =3D bond->params.updelay; > >>> > >>> -=09=09=09if (slave->delay) { > >>> +=09=09=09if (slave->delay && !bond->rtnl_needed) { > >>> =09=09=09=09netdev_info(bond->dev, "link status up for > >> interface %s, enabling it in %d ms\n", > >>> =09=09=09=09=09 slave->dev->name, > >>> =09=09=09=09=09 ignore_updelay ? 0 : > >>> @@ -2301,9 +2301,11 @@ static void bond_mii_monitor(struct > >> work_struct *work) > >>> =09=09if (!rtnl_trylock()) { > >>> =09=09=09delay =3D 1; > >>> =09=09=09should_notify_peers =3D false; > >>> +=09=09=09bond->rtnl_needed =3D true; > >> > >> How can you set a shared variable with no synchronization ? > > Thanks Eric for reviewing the patch. rtnl_needed is not a shared variab= le, it > is part of bonding structure, that is one per bonding driver instance. Th= ere > can't be two parallel instances of bond_miimon_inspect for a single =C2= =A0bonding > driver instance at any given point of time. and only bond_miimon_inspect > updates it. That=E2=80=99s why I think there is no need of any synchroniz= ation here. > > > > >=20 > If rtnl_trylock() can not grab RTNL, > there is no way the current thread can set the variable without a race, = if the > word including rtnl_needed is shared by other fields in the structure. >=20 > Your patch adds a subtle possibility of future bugs, even if it runs fine= today. >=20 > Do not pave the way for future bugs, make your code robust, please. Thankyou Eric, we are making the changes and will repost the patch after te= sting it. -Manish >=20 >=20 >=20 >=20 >=20 >=20 >=20