On Fri, Feb 01, 2019 at 11:45:45AM +0530, Viresh Kumar wrote: > 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 <[email protected]> > --- > drivers/cpufreq/cpufreq_stats.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c > index 941e63e3e652..e2db5581489a 100644 > --- a/drivers/cpufreq/cpufreq_stats.c > +++ b/drivers/cpufreq/cpufreq_stats.c > @@ -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); > }
Reviewed-by: Matthias Kaehlcke <[email protected]>
