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authorViresh Kumar <viresh.kumar@linaro.org>2015-01-06 21:09:15 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-01-23 23:06:45 +0100
commit490285c65e2398a533035dd9d75cb606a61ea39a (patch)
treee18fa0f20423f9838e3bafe5e7f036fc4b75ae33 /drivers/cpufreq/cpufreq_stats.c
parente73476949c6d1e2edd04bbf7b5bae30afa370e33 (diff)
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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>
Diffstat (limited to 'drivers/cpufreq/cpufreq_stats.c')
-rw-r--r--drivers/cpufreq/cpufreq_stats.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index c948086a332b..5e370a30a964 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);