From: Andrew Morton <akpm@osdl.org>

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

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

Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

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

diff -puN drivers/acpi/processor_perflib.c~powernow-k8-crash-workaround drivers/acpi/processor_perflib.c
--- devel/drivers/acpi/processor_perflib.c~powernow-k8-crash-workaround	2006-05-11 15:17:48.000000000 -0700
+++ devel-akpm/drivers/acpi/processor_perflib.c	2006-05-11 15:17:48.000000000 -0700
@@ -773,6 +773,8 @@ acpi_processor_register_performance(stru
 		return -EBUSY;
 	}
 
+	WARN_ON(!performance);
+
 	pr->performance = performance;
 
 	if (acpi_processor_get_performance_info(pr)) {
@@ -803,7 +805,8 @@ acpi_processor_unregister_performance(st
 		return;
 	}
 
-	kfree(pr->performance->states);
+	if (pr->performance)
+		kfree(pr->performance->states);
 	pr->performance = NULL;
 
 	acpi_cpufreq_remove_file(pr);
_