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 <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index c948086..5e370a3 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -207,12 +207,10 @@
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 @@
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);