From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760819AbdEVSIq (ORCPT ); Mon, 22 May 2017 14:08:46 -0400 Received: from www.llwyncelyn.cymru ([82.70.14.225]:49896 "EHLO fuzix.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758110AbdEVSIp (ORCPT ); Mon, 22 May 2017 14:08:45 -0400 Date: Mon, 22 May 2017 19:07:51 +0100 From: Alan Cox To: Rasmus Villemoes Cc: , , , Sebastian Reichel , , Guenter Roeck Subject: Re: [PATCH v5 0/3] watchdog: allow setting deadline for opening /dev/watchdogN Message-ID: <20170522190751.5bf5e813@alans-desktop> In-Reply-To: <1495462000-28979-1-git-send-email-rasmus.villemoes@prevas.dk> References: <1495462000-28979-1-git-send-email-rasmus.villemoes@prevas.dk> Organization: Intel Corporation X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 22 May 2017 16:06:36 +0200 Rasmus Villemoes wrote: > If a watchdog driver tells the framework that the device is running, > the framework takes care of feeding the watchdog until userspace opens > the device. If the userspace application which is supposed to do that > never comes up properly, the watchdog is fed indefinitely by the > kernel. This can be especially problematic for embedded devices. > > These patches allow one to set a maximum time for which the kernel > will feed the watchdog, thus ensuring that either userspace has come > up, or the board gets reset. This allows fallback logic in the > bootloader to attempt some recovery (for example, if an automatic > update is in progress, it could roll back to the previous version). This makes sense except for being a CONFIG_ option not a boot parameter. If it's a boot parameter then the same kernel works for multiple systems and is general. If it's compile time then you have to build a custom kernel. For some embedded stuff that might not matter (although I bet they'd prefer it command line/device tree too) but for something like an x86 platform where you are deploying a standard vendor supplied kernel it's bad to do it that way IMHO. In other words I think you should drop patch 3 but the rest is good. Alan