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cpufreq: stats: Fix concurrency issues while resetting stats

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It is possible for cpufreq_stats_clear_table() and
cpufreq_stats_record_transition() to get called concurrently and they
will try to update same variables simultaneously and may lead to
corruption of data.

Prevent that with the help of existing spinlock.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Viresh Kumar 2019-02-01 11:45:45 +05:30 committed by Rafael J. Wysocki
parent 10b818211d
commit 9795607dc4
1 changed files with 7 additions and 2 deletions
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9
drivers/cpufreq/cpufreq_stats.c
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@ -31,20 +31,20 @@ static void cpufreq_stats_update(struct cpufreq_stats *stats)
{
unsigned long long cur_time = get_jiffies_64();
spin_lock(&cpufreq_stats_lock);
stats->time_in_state[stats->last_index] += cur_time - stats->last_time;
stats->last_time = cur_time;
spin_unlock(&cpufreq_stats_lock);
}
static void cpufreq_stats_clear_table(struct cpufreq_stats *stats)
{
unsigned int count = stats->max_state;
spin_lock(&cpufreq_stats_lock);
memset(stats->time_in_state, 0, count * sizeof(u64));
memset(stats->trans_table, 0, count * count * sizeof(int));
stats->last_time = get_jiffies_64();
stats->total_trans = 0;
spin_unlock(&cpufreq_stats_lock);
}
static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
@ -62,7 +62,10 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
if (policy->fast_switch_enabled)
return 0;
spin_lock(&cpufreq_stats_lock);
cpufreq_stats_update(stats);
spin_unlock(&cpufreq_stats_lock);
for (i = 0; i < stats->state_num; i++) {
len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
(unsigned long long)
@ -239,9 +242,11 @@ void cpufreq_stats_record_transition(struct cpufreq_policy *policy,
if (old_index == -1 || new_index == -1 || old_index == new_index)
return;
spin_lock(&cpufreq_stats_lock);
cpufreq_stats_update(stats);
stats->last_index = new_index;
stats->trans_table[old_index * stats->max_state + new_index]++;
stats->total_trans++;
spin_unlock(&cpufreq_stats_lock);
}