Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934584Ab3DHH4k (ORCPT ); Mon, 8 Apr 2013 03:56:40 -0400 Received: from mail1.bemta12.messagelabs.com ([216.82.251.2]:41654 "EHLO mail1.bemta12.messagelabs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934313Ab3DHH4g (ORCPT ); Mon, 8 Apr 2013 03:56:36 -0400 X-Greylist: delayed 395 seconds by postgrey-1.27 at vger.kernel.org; Mon, 08 Apr 2013 03:56:36 EDT X-Env-Sender: Hector.Palacios@digi.com X-Msg-Ref: server-12.tower-29.messagelabs.com!1365407398!23986163!1 X-Originating-IP: [66.77.174.14] X-StarScan-Received: X-StarScan-Version: 6.8.6.1; banners=-,-,- X-VirusChecked: Checked Message-ID: <51627669.1070900@digi.com> Date: Mon, 8 Apr 2013 09:48:57 +0200 From: Hector Palacios Organization: Digi International User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: Guenter Roeck CC: "linux-watchdog@vger.kernel.org" , "wim@iguana.be" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH RFC] watchdog: core: don't try to stop device if not running References: <515EF748.6060504@digi.com> <20130405183450.GA29835@roeck-us.net> In-Reply-To: <20130405183450.GA29835@roeck-us.net> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3195 Lines: 81 On 04/05/2013 08:34 PM, Guenter Roeck wrote: > On Fri, Apr 05, 2013 at 06:09:44PM +0200, Hector Palacios wrote: >> A watchdog device may be stopped from userspace using WDIOC_SETOPTIONS >> ioctl and flag WDIOS_DISABLECARD. If the device is closed after this >> operation, watchdog_release() is called and status bits checked for >> stopping it. Besides, if the device has not been unregistered a critical >> message "watchdog did not stop!" is printed, although the ioctl may have >> successfully stopped it already. >> >> Without the patch a user application sample code like this will successfully >> stop the watchdog, but the kernel will output the message >> "watchdog did not stop!": >> >> wd_fd = open("/dev/watchdog", O_RDWR); >> >> flags = WDIOS_DISABLECARD; >> ioctl(wd_fd, WDIOC_SETOPTIONS, &flags); >> >> close(wd_fd); >> >> Signed-off-by: Hector Palacios > > How about the following patch instead ? > > diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c > index 08b48bb..9775e8d 100644 > --- a/drivers/watchdog/watchdog_dev.c > +++ b/drivers/watchdog/watchdog_dev.c > @@ -469,7 +469,9 @@ static int watchdog_release(struct inode *inode, struct file *file) > * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then > * watchdog_stop will fail. > */ > - if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) || > + if (!test_bit(WDOG_ACTIVE, &wdd->status)) > + err = 0; > + else if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) || > !(wdd->info->options & WDIOF_MAGICCLOSE)) > err = watchdog_stop(wdd); > > Much less invasive and the result is the same. I like the simplicity but it is kind of inverted logic to initially define err = -EBUSY only to turn it to zero later, so I'm rebuilding your approach like this: diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index ef8edec..a4163cd 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -463,16 +463,19 @@ out: static int watchdog_release(struct inode *inode, struct file *file) { struct watchdog_device *wdd = file->private_data; - int err = -EBUSY; + int err = 0; /* * We only stop the watchdog if we received the magic character * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then * watchdog_stop will fail. */ - if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) || - !(wdd->info->options & WDIOF_MAGICCLOSE)) + if (test_bit(WDOG_ACTIVE, &wdd->status)) + err = -EBUSY; + else if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) || + !(wdd->info->options & WDIOF_MAGICCLOSE)) { err = watchdog_stop(wdd); + } /* If the watchdog was not stopped, send a keepalive ping */ which makes the code more readable. Thanks, -- H?ctor Palacios -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/