From 490285c65e2398a533035dd9d75cb606a61ea39a Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Tue, 6 Jan 2015 21:09:15 +0530 Subject: [PATCH] cpufreq: stats: drop unnecessary locking There is no possibility of any race on updating last_index, trans_table or total_trans as these are updated only by cpufreq_stat_notifier_trans() which will be called sequentially. The only place where locking is still relevant is: cpufreq_stats_update(), which updates time_in_state and last_time. This can be called by two thread in parallel, that may result in races. The two threads being: - sysfs read of time_in_state - and frequency transition that calls cpufreq_stat_notifier_trans(). Remove locking from the first case mentioned above. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq_stats.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c index c948086a332bae..5e370a30a964f5 100644 --- a/drivers/cpufreq/cpufreq_stats.c +++ b/drivers/cpufreq/cpufreq_stats.c @@ -207,12 +207,10 @@ static int __cpufreq_stats_create_table(struct cpufreq_policy *policy) cpufreq_for_each_valid_entry(pos, table) if (freq_table_get_index(stats, pos->frequency) == -1) stats->freq_table[i++] = pos->frequency; - stats->state_num = i; - spin_lock(&cpufreq_stats_lock); + stats->state_num = i; stats->last_time = get_jiffies_64(); stats->last_index = freq_table_get_index(stats, policy->cur); - spin_unlock(&cpufreq_stats_lock); policy->stats = stats; ret = sysfs_create_group(&policy->kobj, &stats_attr_group); @@ -294,13 +292,11 @@ static int cpufreq_stat_notifier_trans(struct notifier_block *nb, cpufreq_stats_update(stats); - spin_lock(&cpufreq_stats_lock); stats->last_index = new_index; #ifdef CONFIG_CPU_FREQ_STAT_DETAILS stats->trans_table[old_index * stats->max_state + new_index]++; #endif stats->total_trans++; - spin_unlock(&cpufreq_stats_lock); put_policy: cpufreq_cpu_put(policy);