1 files changed, 25 insertions, 8 deletions

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 00d73fc8e4e2..faf7c5217848 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -165,17 +165,27 @@ static int freq_table_get_index(struct cpufreq_stats *stat, unsigned int freq)
 	return -1;
 }
 
+/* should be called late in the CPU removal sequence so that the stats
+ * memory is still available in case someone tries to use it.
+ */
 static void cpufreq_stats_free_table(unsigned int cpu)
 {
 	struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, cpu);
-	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
-	if (policy && policy->cpu == cpu)
-		sysfs_remove_group(&policy->kobj, &stats_attr_group);
 	if (stat) {
 		kfree(stat->time_in_state);
 		kfree(stat);
 	}
 	per_cpu(cpufreq_stats_table, cpu) = NULL;
+}
+
+/* must be called early in the CPU removal sequence (before
+ * cpufreq_remove_dev) so that policy is still valid.
+ */
+static void cpufreq_stats_free_sysfs(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	if (policy && policy->cpu == cpu)
+		sysfs_remove_group(&policy->kobj, &stats_attr_group);
 	if (policy)
 		cpufreq_cpu_put(policy);
 }
@@ -288,11 +298,13 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
 	old_index = stat->last_index;
 	new_index = freq_table_get_index(stat, freq->new);
 
-	cpufreq_stats_update(freq->cpu);
-	if (old_index == new_index)
+	/* We can't do stat->time_in_state[-1]= .. */
+	if (old_index == -1 || new_index == -1)
 		return 0;
 
-	if (old_index == -1 || new_index == -1)
+	cpufreq_stats_update(freq->cpu);
+
+	if (old_index == new_index)
 		return 0;
 
 	spin_lock(&cpufreq_stats_lock);
@@ -316,6 +328,9 @@ static int __cpuinit cpufreq_stat_cpu_callback(struct notifier_block *nfb,
 	case CPU_ONLINE_FROZEN:
 		cpufreq_update_policy(cpu);
 		break;
+	case CPU_DOWN_PREPARE:
+		cpufreq_stats_free_sysfs(cpu);
+		break;
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
 		cpufreq_stats_free_table(cpu);
@@ -324,9 +339,10 @@ static int __cpuinit cpufreq_stat_cpu_callback(struct notifier_block *nfb,
 	return NOTIFY_OK;
 }
 
-static struct notifier_block cpufreq_stat_cpu_notifier __refdata =
-{
+/* priority=1 so this will get called before cpufreq_remove_dev */
+static struct notifier_block cpufreq_stat_cpu_notifier __refdata = {
 	.notifier_call = cpufreq_stat_cpu_callback,
+	.priority = 1,
 };
 
 static struct notifier_block notifier_policy_block = {
@@ -373,6 +389,7 @@ static void __exit cpufreq_stats_exit(void)
 	unregister_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
 	for_each_online_cpu(cpu) {
 		cpufreq_stats_free_table(cpu);
+		cpufreq_stats_free_sysfs(cpu);
 	}
 }