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Date: Wed, 25 Nov 2009 23:07:20 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Andrew Morton <akpm@linux-foundation.org>
cc: =?ISO-8859-15?Q?Uwe_Kleine-K=F6nig?= 
	<u.kleine-koenig@pengutronix.de>,
       linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Luming Yu <luming.yu@gmail.com>
Subject: Re: [PATCH 1/2] hrtimer: correct a few numbers in comments and printk
 outputs
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On Wed, 25 Nov 2009, Andrew Morton wrote:
> On Wed, 25 Nov 2009 21:18:39 +0100 (CET)
> Thomas Gleixner <tglx@linutronix.de> wrote:
> > > > > @@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_
> > > > >  				dev->min_delta_ns += dev->min_delta_ns >> 1;
> > > > >  
> > > > >  			printk(KERN_WARNING
> > > > > -			       "CE: %s increasing min_delta_ns to %lu nsec\n",
> > > > > +			       "CE: %s increasing min_delta_ns to %llu nsec\n",
> > > > >  			       dev->name ? dev->name : "?",
> > > > > -			       dev->min_delta_ns << 1);
> > > > > +			       (unsigned long long) dev->min_delta_ns << 1);
> > > > '<< 1' is wrong here, too.
> > > > 
> > > 
> > > What's wrong with it?  That leftshift appears to be to compensate for
> > > the rightshift a few lines above.
> > > 
> > > That change was unobvious and unchangelogged, so here we are again.
> > 
> > That's actually my fault. In commit 61c22c34 I removed the WARN_ON
> > which we put there to gather data on kerneloops.org for a while and
> > did not fix the printk format string.
> > 
> 
> The issue is not the format string.  I'm wondering why Uwe removed that
> left-shift of dev->min_delta_ns.

Sorry, I'm confused: I did not fix the argument. The printk was
actually before the code which adjusted the min_delta_ns in the old
WARN_ON case. When I removed the WARN_ON I moved the printk down and
kept the << 1 which is crap. We want to print the new value not the
double of it.

Thanks,

	tglx