linux-kernel - Re: 2.6.27-rc1: critical thermal shutdown on thinkpad x60 (bisected)

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Message-ID: <48A1B0CB.9050908@redhat.com>
Date:	Tue, 12 Aug 2008 17:48:27 +0200
From:	Milan Broz <mbroz@...hat.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Pavel Machek <pavel@...e.cz>, Andi Kleen <andi@...stfloor.org>,
	kernel list <linux-kernel@...r.kernel.org>,
	ACPI mailing list <linux-acpi@...r.kernel.org>,
	Alexey Starikovskiy <astarikovskiy@...e.de>,
	Thomas Renninger <trenn@...e.de>
Subject: Re: 2.6.27-rc1: critical thermal shutdown on thinkpad x60 (bisected)


>>>> yes. maybe some userspace tool controlling frequency is involved, no idea yet.
>>>> But it is 2.6.26 tree for sure.
>>>>         
>>> So it definitely is in 2.6.26.2, and it definitely is in 2.6.26?
>>>       
>
>
> The bug is _not_ in 2.6.26, it was introduced in 2.6.26.1.
>
> The problem is, that now the CPU frequency doesn't decrease at some
> temperature level and fan is unable to cool it properly.
>
> bisect on 2.6.26.y tree finished in this patch:
> (I expect similar patch in 2.6.27-rc)
>
> commit 04f496871e8af87a1e40c504371a206fd7389193
> Author: Thomas Renninger <trenn@...e.de>
> Date:   Wed Jul 30 18:20:10 2008 +0000
>
>   
and this seems to fix it for me:
--

Do not use unsigned int if there is test for negative number...

See drivers/acpi/processor_perflib.c
  static unsigned int ignore_ppc = -1;
...
  if (event == CPUFREQ_START && ignore_ppc <= 0) {
       ignore_ppc = 0;
...

Signed-off-by: Milan Broz <mbroz@...hat.com>
---
 drivers/acpi/processor_perflib.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.26.y/drivers/acpi/processor_perflib.c
===================================================================
--- linux-2.6.26.y.orig/drivers/acpi/processor_perflib.c	2008-08-12 17:20:07.000000000 +0200
+++ linux-2.6.26.y/drivers/acpi/processor_perflib.c	2008-08-12 17:35:53.000000000 +0200
@@ -70,7 +70,7 @@ static DEFINE_MUTEX(performance_mutex);
  *  0 -> cpufreq low level drivers initialized -> consider _PPC values
  *  1 -> ignore _PPC totally -> forced by user through boot param
  */
-static unsigned int ignore_ppc = -1;
+static int ignore_ppc = -1;
 module_param(ignore_ppc, uint, 0644);
 MODULE_PARM_DESC(ignore_ppc, "If the frequency of your machine gets wrongly" \
 		 "limited by BIOS, this should help");


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