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=-5.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 32528C433E7 for ; Wed, 2 Sep 2020 14:07:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B50C207D3 for ; Wed, 2 Sep 2020 14:07:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727931AbgIBOHo (ORCPT ); Wed, 2 Sep 2020 10:07:44 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:21160 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727919AbgIBNvM (ORCPT ); Wed, 2 Sep 2020 09:51:12 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4BhPgP6btKz9txSj; Wed, 2 Sep 2020 15:20:01 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id 13JB8Zw2mRHx; Wed, 2 Sep 2020 15:20:01 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4BhPgP5Fxbz9txSG; Wed, 2 Sep 2020 15:20:01 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 224D08B7EA; Wed, 2 Sep 2020 15:20:03 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id LzA1l6PiP3U8; Wed, 2 Sep 2020 15:20:03 +0200 (CEST) Received: from [10.25.210.31] (po15451.idsi0.si.c-s.fr [10.25.210.31]) by messagerie.si.c-s.fr (Postfix) with ESMTP id E8F728B7E9; Wed, 2 Sep 2020 15:20:02 +0200 (CEST) Subject: Re: watchdog start on restart To: Ivan Mikhaylov Cc: Wim Van Sebroeck , Guenter Roeck , linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Christophe Leroy Message-ID: Date: Wed, 2 Sep 2020 15:19:56 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 02/09/2020 à 15:02, Ivan Mikhaylov a écrit : > Hello everyone. Currently, the watchdog interface only has "stop watchdog on > restart" but lacks a "start watchdog on restart" one. Is there a way to achieve > such functionality? > > I'd like to know why "stop watchdog on restart" wasn't implemented via ioctl > interface? It would be more convenient from user perspective and you can > control that behavior whenever you want from application layer. > > I have some thoughts on this problem that solve the aforementioned > issue with "start watchdog on restart" but I don't think that my solution is > correct. > I don't understand why a "start watchdog on restart" would be needed. Isn't it the default expected behaviour for a watchdog ? "stop watchdog on restart" is there to keep things under control during a wanted machine reboot/restart, while still having the watchdog do its job on an unexpected restart. What would be the advantage of an ioctl() compared to the existing way ? Christophe