linux-kernel - Re: [PATCH] watchdog: touch_nmi_watchdog should only touch local cpu not every one

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Message-ID: <20101108133745.GJ4823@redhat.com>
Date:	Mon, 8 Nov 2010 08:37:45 -0500
From:	Don Zickus <dzickus@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	fweisbec@...il.com, Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] watchdog:  touch_nmi_watchdog should only touch local
 cpu not every one

On Fri, Nov 05, 2010 at 12:58:55PM -0700, Andrew Morton wrote:
> On Fri, 5 Nov 2010 15:51:18 +0200
> Sergey Senozhatsky <sergey.senozhatsky@...il.com> wrote:
> 
> > On (11/04/10 21:18), Don Zickus wrote:
> > >  void touch_nmi_watchdog(void)
> > >  {
> > > +	/*
> > > +	 * Using __raw here because some code paths have
> > > +	 * preemption enabled.  If preemption is enabled
> > > +	 * then interrupts should be enabled too, in which
> > > +	 * case we shouldn't have to worry about the watchdog
> > > +	 * going off.
> > > +	 */
> > > +	__raw_get_cpu_var(watchdog_nmi_touch) = true;
> > > +
> > > +	touch_softlockup_watchdog();
> > > +}
> > > +EXPORT_SYMBOL(touch_nmi_watchdog);
> > > +
> > > +void touch_all_nmi_watchdogs(void)
> > > +{
> > >  	if (watchdog_enabled) {
> > >  		unsigned cpu;
> > >  
> > > @@ -151,7 +166,7 @@ void touch_nmi_watchdog(void)
> > >  	}
> > >  	touch_softlockup_watchdog();
> > >  }
> > > -EXPORT_SYMBOL(touch_nmi_watchdog);
> > > +EXPORT_SYMBOL(touch_all_nmi_watchdogs);
> > >  
> > 
> > Hello,
> > Seems like no one is actually calling touch_all_nmi_watchdogs, as for now. 
> > Right?
> 
> Yes, there doesn't seem a lot of point in adding the interface unless
> we have callers.

Yeah I wasn't sure how to deal with that.  It didn't seem like any of the
callers was relying on the fact that touch_nmi_watchdog() touched
everyone.  I just provided it as an option in case I misread someone's use
of the touch_nmi_watchdog.

I'll repost and remove it then.

Thanks for the feedback.

Cheers,
Don
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