From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from bh-25.webhostbox.net ([208.91.199.152]:39082 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754031AbbLVQPo (ORCPT ); Tue, 22 Dec 2015 11:15:44 -0500 Subject: Re: [PATCH 1/5] watchdog: Create watchdog device in watchdog_dev.c To: Damien Riegel , linux-watchdog@vger.kernel.org, Wim Van Sebroeck , Pratyush Anand , Hans de Goede , linux-kernel@vger.kernel.org References: <1450645503-16661-1-git-send-email-linux@roeck-us.net> <1450645503-16661-2-git-send-email-linux@roeck-us.net> <20151221173123.GD12696@localhost> <56788B27.20706@roeck-us.net> <20151222153337.GB6164@localhost> From: Guenter Roeck Message-ID: <5679772D.8030806@roeck-us.net> Date: Tue, 22 Dec 2015 08:15:41 -0800 MIME-Version: 1.0 In-Reply-To: <20151222153337.GB6164@localhost> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org On 12/22/2015 07:33 AM, Damien Riegel wrote: > On Mon, Dec 21, 2015 at 03:28:39PM -0800, Guenter Roeck wrote: >> On 12/21/2015 09:31 AM, Damien Riegel wrote: >>> On Sun, Dec 20, 2015 at 01:04:59PM -0800, Guenter Roeck wrote: >>>> The watchdog character device is currently created in watchdog_dev.c, >>>> and the watchdog device in watchdog_core.c. This results in >>>> cross-dependencies, since device creation needs to know the watchdog >>>> character device number as well as the watchdog class, both of which >>>> reside in watchdog_dev.c. >>>> >>>> Create the watchdog device in watchdog_dev.c to simplify the code. >>>> >>>> Inspired by earlier patch set from Damien Riegel. >>> >>> Hi Guenter, >>> >>> The main purpose of my patch was to inverse the device creation and the >>> cdev registration to avoid a racy situation, bu you have dropped that in >>> this version. Is there a reason for that? >>> >> Every other driver I looked at does it in the same order (cdev first, device >> second). I don't really know if doing it differently has any undesired >> side effect, so I wanted to play safe. >> >> It would help a lot if someone listening to this exchange can confirm >> that it is ok to create the device first, followed by the character device. > > The issue is that some drivers use watchdog_device->dev in their > watchdog_ops functions. With a quick grep, I could spot 3 examples: > > - bcm2835_wdt_stop in bcm2835_wdt.c > - gpio_wdt_hwping in gpio_wdt.c > - a21_wdt_set_timeout in mena21_wdt.c > > Maybe we should simply fix these drivers and keep watchdog_device->dev > for core internal usage? > Yes, I have been thinking about that - essentially move the ->dev pointer to the internal data structure and either use pr_ functions in those drivers, or save a pointer to the platform device (if available) and use it. I think I'll start working on a follow-up patch set to do just that. Guenter