[patch 2/2] CPUFREQ ondemand/conservative: Clean up mutex usage

[trenn@xxxxxxx]

There is no need to take a lock when nothing is done.
Lock after checking whether userspace provides sane data.


Signed-off-by: Thomas Renninger <trenn@xxxxxxx>

---
 drivers/cpufreq/cpufreq_conservative.c |   19 +++++++------------
 drivers/cpufreq/cpufreq_ondemand.c     |   18 ++++++++----------
 2 files changed, 15 insertions(+), 22 deletions(-)

Index: linux-2.6.29-master/drivers/cpufreq/cpufreq_conservative.c
===================================================================
--- linux-2.6.29-master.orig/drivers/cpufreq/cpufreq_conservative.c
+++ linux-2.6.29-master/drivers/cpufreq/cpufreq_conservative.c
@@ -264,13 +264,11 @@ static ssize_t store_up_threshold(struct
 	int ret;
 	ret = sscanf(buf, "%u", &input);
 
-	mutex_lock(&dbs_mutex);
 	if (ret != 1 || input > 100 ||
-			input <= dbs_tuners_ins.down_threshold) {
-		mutex_unlock(&dbs_mutex);
+			input <= dbs_tuners_ins.down_threshold)
 		return -EINVAL;
-	}
 
+	mutex_lock(&dbs_mutex);
 	dbs_tuners_ins.up_threshold = input;
 	mutex_unlock(&dbs_mutex);
 
@@ -284,14 +282,12 @@ static ssize_t store_down_threshold(stru
 	int ret;
 	ret = sscanf(buf, "%u", &input);
 
-	mutex_lock(&dbs_mutex);
 	/* cannot be lower than 11 otherwise freq will not fall */
 	if (ret != 1 || input < 11 || input > 100 ||
-			input >= dbs_tuners_ins.up_threshold) {
-		mutex_unlock(&dbs_mutex);
+			input >= dbs_tuners_ins.up_threshold)
 		return -EINVAL;
-	}
 
+	mutex_lock(&dbs_mutex);
 	dbs_tuners_ins.down_threshold = input;
 	mutex_unlock(&dbs_mutex);
 
@@ -313,11 +309,10 @@ static ssize_t store_ignore_nice_load(st
 	if (input > 1)
 		input = 1;
 
-	mutex_lock(&dbs_mutex);
-	if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
-		mutex_unlock(&dbs_mutex);
+	if (input == dbs_tuners_ins.ignore_nice) /* nothing to do */
 		return count;
-	}
+
+	mutex_lock(&dbs_mutex);
 	dbs_tuners_ins.ignore_nice = input;
 
 	/* we need to re-evaluate prev_cpu_idle */
Index: linux-2.6.29-master/drivers/cpufreq/cpufreq_ondemand.c
===================================================================
--- linux-2.6.29-master.orig/drivers/cpufreq/cpufreq_ondemand.c
+++ linux-2.6.29-master/drivers/cpufreq/cpufreq_ondemand.c
@@ -266,11 +266,10 @@ static ssize_t store_sampling_rate(struc
 	int ret;
 	ret = sscanf(buf, "%u", &input);
 
-	mutex_lock(&dbs_mutex);
-	if (ret != 1) {
-		mutex_unlock(&dbs_mutex);
+	if (ret != 1)
 		return -EINVAL;
-	}
+
+	mutex_lock(&dbs_mutex);
 	dbs_tuners_ins.sampling_rate = max(input, minimum_sampling_rate());
 	mutex_unlock(&dbs_mutex);
 
@@ -284,13 +283,12 @@ static ssize_t store_up_threshold(struct
 	int ret;
 	ret = sscanf(buf, "%u", &input);
 
-	mutex_lock(&dbs_mutex);
+
 	if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
-			input < MIN_FREQUENCY_UP_THRESHOLD) {
-		mutex_unlock(&dbs_mutex);
+			input < MIN_FREQUENCY_UP_THRESHOLD)
 		return -EINVAL;
-	}
 
+	mutex_lock(&dbs_mutex);
 	dbs_tuners_ins.up_threshold = input;
 	mutex_unlock(&dbs_mutex);
 
@@ -312,11 +310,11 @@ static ssize_t store_ignore_nice_load(st
 	if (input > 1)
 		input = 1;
 
-	mutex_lock(&dbs_mutex);
 	if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
-		mutex_unlock(&dbs_mutex);
 		return count;
 	}
+
+	mutex_lock(&dbs_mutex);
 	dbs_tuners_ins.ignore_nice = input;
 
 	/* we need to re-evaluate prev_cpu_idle */

--
To unsubscribe from this list: send the line "unsubscribe cpufreq" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html