cpufreq: governor: Move rate_mult to struct policy_dbs

The rate_mult field in struct od_cpu_dbs_info_s is used by the code
shared with the conservative governor and to access it that code
has to do an ugly governor type check.  However, first of all it
is ever only used for policy->cpu, so it is per-policy rather than
per-CPU and second, it is initialized to 1 by cpufreq_governor_start(),
so if the conservative governor never modifies it, it will have no
effect on the results of any computations.

For these reasons, move rate_mult to struct policy_dbs_info (as a
common field).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 15 insertions, 8 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 707c017f4e67..812d9949a0c4 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -164,7 +164,7 @@ static void od_update(struct cpufreq_policy *policy)
 	if (load > dbs_data->up_threshold) {
 		/* If switching to max speed, apply sampling_down_factor */
 		if (policy->cur < policy->max)
-			dbs_info->rate_mult = dbs_data->sampling_down_factor;
+			policy_dbs->rate_mult = dbs_data->sampling_down_factor;
 		dbs_freq_increase(policy, policy->max);
 	} else {
 		/* Calculate the next frequency proportional to load */
@@ -175,7 +175,7 @@ static void od_update(struct cpufreq_policy *policy)
 		freq_next = min_f + load * (max_f - min_f) / 100;
 
 		/* No longer fully busy, reset rate_mult */
-		dbs_info->rate_mult = 1;
+		policy_dbs->rate_mult = 1;
 
 		if (!od_tuners->powersave_bias) {
 			__cpufreq_driver_target(policy, freq_next,
@@ -214,7 +214,7 @@ static unsigned int od_dbs_timer(struct cpufreq_policy *policy)
 			delay = dbs_info->freq_hi_jiffies;
 		} else {
 			delay = delay_for_sampling_rate(dbs_data->sampling_rate
-							* dbs_info->rate_mult);
+							* policy_dbs->rate_mult);
 		}
 	}
 
@@ -266,20 +266,27 @@ static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 		const char *buf, size_t count)
 {
-	unsigned int input, j;
+	struct policy_dbs_info *policy_dbs;
+	unsigned int input;
 	int ret;
 	ret = sscanf(buf, "%u", &input);
 
 	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 		return -EINVAL;
+
 	dbs_data->sampling_down_factor = input;
 
 	/* Reset down sampling multiplier in case it was active */
-	for_each_online_cpu(j) {
-		struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
-				j);
-		dbs_info->rate_mult = 1;
+	list_for_each_entry(policy_dbs, &dbs_data->policy_dbs_list, list) {
+		/*
+		 * Doing this without locking might lead to using different
+		 * rate_mult values in od_update() and od_dbs_timer().
+		 */
+		mutex_lock(&policy_dbs->timer_mutex);
+		policy_dbs->rate_mult = 1;
+		mutex_unlock(&policy_dbs->timer_mutex);
 	}
+
 	return count;
 }