linux-kernel - Re: [PATCH 1/1] Watchdog: Fixed the watchdog close/stop logic - only close the watchdog if the magic character was received and the magic close is supported.

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Message-ID: <20141209081934.GN8811@spo001.leaseweb.nl>
Date:	Tue, 9 Dec 2014 09:19:34 +0100
From:	Wim Van Sebroeck <wim@...ana.be>
To:	Robert Yang <hachyang@...il.com>
Cc:	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
	ryang <ryang@...h.com>
Subject: Re: [PATCH 1/1] Watchdog: Fixed the watchdog close/stop logic - only close the watchdog if the magic character was received and the magic close is supported.

Hi Ryang,

> From: ryang <ryang@...h.com>
> 
> Signed-off-by: ryang <ryang@...h.com>
> ---
>  drivers/watchdog/watchdog_dev.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 6aaefba..73793d8 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -471,8 +471,8 @@ static int watchdog_release(struct inode *inode, struct file *file)
>  	 */
>  	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))
> +	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 */
> -- 

There is no reason for this change; you either have:
1) WDIOF_MAGICCLOSE is not supported and thus watchog may be stopped.
2) If a watchdog daemon crashes and thus closes the watchdog device (and thus it did not sent a Magic Char) then the watchdog should not be stopped but needs to reboot the system.

Kind regards,
Wim.

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