[CPUFREQ] Bug fix for acpi-cpufreq and cpufreq_stats oops on frequency change notification

Fixes the oops in cpufreq_stats with acpi_cpufreq driver.  The issue was
that the frequency was reported as 0 in acpi-cpufreq.c.  The bug is due to
different indicies for freq_table and ACPI perf table.

Also adds a check in cpufreq_stats to check for error return from
freq_table_get_index() and avoid using the error return value.

Patch fixes the issue reported at
http://www.ussg.iu.edu/hypermail/linux/kernel/0611.2/0629.html
and also other similar issue here
http://bugme.osdl.org/show_bug.cgi?id=7383 comment 53

Signed-off-by: Dhaval Giani <dhaval.giani@gmail.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 6742b1adf2c8..91ad342a6051 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -285,6 +285,7 @@ cpufreq_stat_notifier_trans (struct notifier_block *nb, unsigned long val,
         stat = cpufreq_stats_table[freq->cpu];
         if (!stat)
                 return 0;
+
         old_index = freq_table_get_index(stat, freq->old);
         new_index = freq_table_get_index(stat, freq->new);
 
@@ -292,6 +293,9 @@ cpufreq_stat_notifier_trans (struct notifier_block *nb, unsigned long val,
         if (old_index == new_index)
                 return 0;
 
+        if (old_index == -1 || new_index == -1)
+                return 0;
+
         spin_lock(&cpufreq_stats_lock);
         stat->last_index = new_index;
 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS