linux-kernel - Re: [BUG?] false positive in soft lockup detector while unlzma initramfs on slow cpu

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Message-ID: <1359561552.1641.218.camel@anish-Inspiron-N5050>
Date:	Wed, 30 Jan 2013 21:29:12 +0530
From:	anish kumar <anish198519851985@...il.com>
To:	Don Zickus <dzickus@...hat.com>
Cc:	Mike Lykov <combr@...dex.ru>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org,
	kirill@...temov.name
Subject: Re: [BUG?] false positive in soft lockup detector while unlzma
 initramfs on slow cpu

On Wed, 2013-01-30 at 10:51 -0500, Don Zickus wrote:
> On Tue, Jan 29, 2013 at 10:48:27PM +0530, anish kumar wrote:
> > Sorry for digressing from the topic but I think there is something wrong
> > with my understanding or something wrong with the code.So I guess Don
> > can clarify this.
> > If I pass this below parameter during boot i.e. setting watchdog_enabled
> > to zero.
> > __setup("nowatchdog", nowatchdog_setup);
> > 
> > Now I use sysctl to enable the watchdog then wouldn't the below code
> > will hinder enabling the watchdog?
> > 
> > static void watchdog_enable_all_cpus(void)
> > {//snip
> >         if (watchdog_disabled) {  /* this is zero ?? */
> >                 watchdog_disabled = 0;
> > //snip
> > }
> > 
> > Should watchdog_disabled be set to 1?Or is it that we always disable the
> > watchdog and then enable it?
> 
> It seems like a bug, so does something like this fix it?  There is
> probably a better way to handle the internal representation of the
> watchdog state (watchdog_disable) and the procfs version
> (watchdog_enable), but I just can't think of something right now. :-(
> 
> Cheers,
> Don
> 
> 
> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
> index 75a2ab3..d287726 100644
> --- a/kernel/watchdog.c
> +++ b/kernel/watchdog.c
> @@ -82,6 +82,7 @@ __setup("softlockup_panic=", softlockup_panic_setup);
>  static int __init nowatchdog_setup(char *str)
>  {
>  	watchdog_enabled = 0;
> +	watchdog_disabled =1;
I don't know if this will work or not but while going through the code I
spotted this.I will think of something better if I couldn't think of
anything better than anyway we have this patch.
>  	return 1;
>  }
>  __setup("nowatchdog", nowatchdog_setup);


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