Date: Thu, 19 Nov 2009 11:05:17 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Ingo Molnar <mingo@elte.hu>
cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org,
       akpm@linux-foundation.org, heiko.carstens@de.ibm.com,
       feng.tang@intel.com, Fr??d??ric Weisbecker <fweisbec@gmail.com>,
       Steven Rostedt <rostedt@goodmis.org>, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:timers/urgent] hrtimer: Fix /proc/timer_list regression
In-Reply-To: <20091119072040.GA23579@elte.hu>
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References: <alpine.LFD.2.00.0911181933540.24119@localhost.localdomain> <tip-887a29f59b93cf54e21814869a4ab6e80b6fa623@git.kernel.org> <20091119072040.GA23579@elte.hu>
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On Thu, 19 Nov 2009, Ingo Molnar wrote:
> i've bisected back to it:
> 
> | 887a29f59b93cf54e21814869a4ab6e80b6fa623 is the first bad commit
> | commit 887a29f59b93cf54e21814869a4ab6e80b6fa623
> | Author: Feng Tang <feng.tang@intel.com>
> | Date:   Thu Sep 3 16:32:53 2009 +0800
> |
> |    hrtimer: Fix /proc/timer_list regression
> 
> Config attached.
> 
> I've removed it from timers/urgent for now.

Come on, this is a patently wrong conclusion.

We call timer_stats_update_stats() which returns on top of the
function due to:

	if (likely(!timer_stats_active))
		return;

timer_stats_active is 0 during boot and you can only activate it by
writing to /proc/timer_stats which you certainly did not at this
point.

Can you please explain how a call to a function which returns right
away can cause that problem ? 

That patch unearthed some other bug and your revert is just papering
over that fact.

Thanks,

	tglx
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