[PATCH 12/13] powernow-k8 crash workaround

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
------------------

From: Andrew Morton <akpm@xxxxxxxx>

Work around the oops reported in
http://bugzilla.kernel.org/show_bug.cgi?id=6478.

Thanks to Ralf Hildebrandt <ralf.hildebrandt@xxxxxxxxxx> for testing and
reporting.

Acked-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Cc: "Len Brown" <len.brown@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---

 drivers/acpi/processor_perflib.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- linux-2.6.16.21.orig/drivers/acpi/processor_perflib.c
+++ linux-2.6.16.21/drivers/acpi/processor_perflib.c
@@ -577,6 +577,8 @@ acpi_processor_register_performance(stru
 		return_VALUE(-EBUSY);
 	}
 
+	WARN_ON(!performance);
+
 	pr->performance = performance;
 
 	if (acpi_processor_get_performance_info(pr)) {
@@ -609,7 +611,8 @@ acpi_processor_unregister_performance(st
 		return_VOID;
 	}
 
-	kfree(pr->performance->states);
+	if (pr->performance)
+		kfree(pr->performance->states);
 	pr->performance = NULL;
 
 	acpi_cpufreq_remove_file(pr);

--
-
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