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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 2EF60C2D0DB for ; Mon, 27 Jan 2020 11:31:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CB6C214AF for ; Mon, 27 Jan 2020 11:31:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730154AbgA0Lbd (ORCPT ); Mon, 27 Jan 2020 06:31:33 -0500 Received: from esa6.microchip.iphmx.com ([216.71.154.253]:22091 "EHLO esa6.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726428AbgA0Lbc (ORCPT ); Mon, 27 Jan 2020 06:31:32 -0500 Received-SPF: Pass (esa6.microchip.iphmx.com: domain of Allan.Nielsen@microchip.com designates 198.175.253.82 as permitted sender) identity=mailfrom; client-ip=198.175.253.82; receiver=esa6.microchip.iphmx.com; envelope-from="Allan.Nielsen@microchip.com"; x-sender="Allan.Nielsen@microchip.com"; x-conformance=spf_only; x-record-type="v=spf1"; x-record-text="v=spf1 mx a:ushub1.microchip.com a:smtpout.microchip.com -exists:%{i}.spf.microchip.iphmx.com include:servers.mcsv.net include:mktomail.com include:spf.protection.outlook.com ~all" Received-SPF: None (esa6.microchip.iphmx.com: no sender authenticity information available from domain of postmaster@email.microchip.com) identity=helo; client-ip=198.175.253.82; receiver=esa6.microchip.iphmx.com; envelope-from="Allan.Nielsen@microchip.com"; x-sender="postmaster@email.microchip.com"; x-conformance=spf_only Authentication-Results: esa6.microchip.iphmx.com; dkim=none (message not signed) header.i=none; spf=Pass smtp.mailfrom=Allan.Nielsen@microchip.com; spf=None smtp.helo=postmaster@email.microchip.com; dmarc=pass (p=none dis=none) d=microchip.com IronPort-SDR: CHJf1jjbC+hNXjcALXRPG34+geA7/A0vihzr4yW4wdZ4shNAyUBnNGMpFS+3gJUo1GmhjrEcN5 1ayIJgz/ZWq+Y6giZQradd5Kb3HdZ0Wj1az65D7HU91WJu5HvixdXl3+aTU5S2k6cQuY8QYZcm q+yUeb4C+SZGu0zXaR+aYe5NKT1vfPTv8UfKnlDmWEG7CHA9/rDBx/Kma8JmhAgTgCSxufVU77 YFpSAo6/7kw6EIr68WpHCd2V9lmKu9HKGAroxpZsXiNTh7yzohuh5mV6U4G5FRKRhGzjEhzuIy IgY= X-IronPort-AV: E=Sophos;i="5.70,369,1574146800"; d="scan'208";a="189991" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa6.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 27 Jan 2020 04:04:24 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.87.72) by chn-vm-ex02.mchp-main.com (10.10.87.72) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Mon, 27 Jan 2020 04:04:19 -0700 Received: from localhost (10.10.85.251) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server id 15.1.1713.5 via Frontend Transport; Mon, 27 Jan 2020 04:04:19 -0700 Date: Mon, 27 Jan 2020 12:04:18 +0100 From: "Allan W. Nielsen" To: Andrew Lunn CC: Horatiu Vultur , , , , , , , , , , , , Subject: Re: [RFC net-next v3 06/10] net: bridge: mrp: switchdev: Extend switchdev API to offload MRP Message-ID: <20200127110418.f7443ecls6ih2fwt@lx-anielsen.microsemi.net> References: <20200124161828.12206-1-horatiu.vultur@microchip.com> <20200124161828.12206-7-horatiu.vultur@microchip.com> <20200125163504.GF18311@lunn.ch> <20200126132213.fmxl5mgol5qauwym@soft-dev3.microsemi.net> <20200126155911.GJ18311@lunn.ch> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Disposition: inline In-Reply-To: <20200126155911.GJ18311@lunn.ch> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26.01.2020 16:59, Andrew Lunn wrote: >EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > >On Sun, Jan 26, 2020 at 02:22:13PM +0100, Horatiu Vultur wrote: >> The 01/25/2020 17:35, Andrew Lunn wrote: >> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe >> > >> > > SWITCHDEV_OBJ_ID_RING_TEST_MRP: This is used when to start/stop sending >> > > MRP_Test frames on the mrp ring ports. This is called only on nodes that have >> > > the role Media Redundancy Manager. >> > >> > How do you handle the 'headless chicken' scenario? User space tells >> > the port to start sending MRP_Test frames. It then dies. The hardware >> > continues sending these messages, and the neighbours thinks everything >> > is O.K, but in reality the state machine is dead, and when the ring >> > breaks, the daemon is not there to fix it? I agree, we need to find a solution to this issue. >> > And it is not just the daemon that could die. The kernel could opps or >> > deadlock, etc. >> > >> > For a robust design, it seems like SWITCHDEV_OBJ_ID_RING_TEST_MRP >> > should mean: start sending MRP_Test frames for the next X seconds, and >> > then stop. And the request is repeated every X-1 seconds. Sounds like a good idea to me. >> I totally missed this case, I will update this as you suggest. > >What does your hardware actually provide? > >Given the design of the protocol, if the hardware decides the OS etc >is dead, it should stop sending MRP_TEST frames and unblock the ports. >If then becomes a 'dumb switch', and for a short time there will be a >broadcast storm. Hopefully one of the other nodes will then take over >the role and block a port. As far as I know, the only feature HW has to prevent this is a watch-dog timer. Which will reset the entire system (not a bad idea if the kernel has dead-locked). /Allan