linux-kernel - Re: [PATCH RESEND] fix WARNING: at kernel/cpu/idle.c:96

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Message-ID: <alpine.DEB.2.02.1306142245050.24522@ionos.tec.linutronix.de>
Date:	Fri, 14 Jun 2013 22:49:06 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	James Bottomley <James.Bottomley@...senPartnership.com>
cc:	Parisc List <linux-parisc@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH RESEND] fix WARNING: at kernel/cpu/idle.c:96

On Fri, 14 Jun 2013, Thomas Gleixner wrote:
> On Fri, 14 Jun 2013, James Bottomley wrote:
> 
> > >From 48bbf44a96676ce6f520a408378730c976e9a11e Mon Sep 17 00:00:00 2001
> > From: James Bottomley <JBottomley@...allels.com>
> > Date: Wed, 8 May 2013 14:05:34 -0700
> > Subject: [PATCH] [PARISC] fix WARNING: at kernel/cpu/idle.c:96
> > 
> > On PA-RISC (and presumably any other arch that doesn't implement its own
> > arch_cpu_idle), we get this spurious boot warning.  The problem is that the
> > way the idle task is selected initially using the weak arch_cpu_idle() in
> > idle.c causes us to enter this place once with interrupts enabled.  Fix this
> > by disabling interrupts in the weak arch_cpu_idle() code.
> > 
> > Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
> > Cc: stable@...r.kernel.org
> 
> What's the stable tag for? This code got merged in 3,10, so stable is
> totally irrelevant.
> 
> > Signed-off-by: James Bottomley <JBottomley@...allels.com>
> > 
> > ---
> > 
> > Thomas, I'm getting a bit impatient: this is a clear bug in the cpu idle
> > code and we keep getting reports of this as a boot crash on parisc.  If
> > you don't push it through your tree, I'll take it through the parisc
> > one.
> 
> Hold your breath. I was not even CC'ed on the original patch and I
> admit that I ignored the patch which starts with [PARISC].
> 
> If the subject line would have started with [idle], [core/idle] I
> definitely would have paid attention.
> 
> Aside of that the rest of the subject line is just annoyingly
> sloppy. We do not fix a WARNING. That's not what this patch is
> about. The patch fixes a problem which got introduced with the idle
> rework, period.
> 
> I'll pick it up and fix the changelog.

And it needs fixing. It says:

"... way the idle task is selected initially using the weak
 arch_cpu_idle() in idle.c causes us to enter this place once with
 interrupts enabled.  Fix this by disabling interrupts in the weak
 arch_cpu_idle() code."

And the patch does:

 void __weak arch_cpu_idle(void)
 {
        cpu_idle_force_poll = 1;
+       local_irq_enable();
 }

Instead of bullying around you might consider to read
Documentation/SubmittingPatches.

Thanks,

	tglx
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