PM / devfreq: Clean up the devfreq instance name in sysfs attr

The sysfs attr interface used eithere 'df' or 'devfreq' for devfreq instance
name. In order to keep the consistency and to improve the readabilty,
unify the instance name as 'df'. Add add the missing conditional statement
to prevent the fault.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

drivers/devfreq/devfreq.c

@@ -1280,18 +1280,20 @@ EXPORT_SYMBOL(devfreq_remove_governor);
 static ssize_t name_show(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
-	struct devfreq *devfreq = to_devfreq(dev);
+	struct devfreq *df = to_devfreq(dev);
-	return sprintf(buf, "%s\n", dev_name(devfreq->dev.parent));
+	return sprintf(buf, "%s\n", dev_name(df->dev.parent));
 }
 static DEVICE_ATTR_RO(name);
 
 static ssize_t governor_show(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
-	if (!to_devfreq(dev)->governor)
+	struct devfreq *df = to_devfreq(dev);
+
+	if (!df->governor)
 		return -EINVAL;
 
-	return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
+	return sprintf(buf, "%s\n", df->governor->name);
 }
 
 static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
@@ -1302,6 +1304,9 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 	char str_governor[DEVFREQ_NAME_LEN + 1];
 	const struct devfreq_governor *governor, *prev_governor;
 
+	if (!df->governor)
+		return -EINVAL;
+
 	ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
 	if (ret != 1)
 		return -EINVAL;
@@ -1315,20 +1320,18 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 	if (df->governor == governor) {
 		ret = 0;
 		goto out;
-	} else if ((df->governor && df->governor->immutable) ||
+	} else if (df->governor->immutable || governor->immutable) {
-					governor->immutable) {
 		ret = -EINVAL;
 		goto out;
 	}
 
-	if (df->governor) {
+	ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
-		ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
+	if (ret) {
-		if (ret) {
+		dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
-			dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
+			 __func__, df->governor->name, ret);
-				 __func__, df->governor->name, ret);
+		goto out;
-			goto out;
-		}
 	}
+
 	prev_governor = df->governor;
 	df->governor = governor;
 	strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
@@ -1363,13 +1366,16 @@ static ssize_t available_governors_show(struct device *d,
 	struct devfreq *df = to_devfreq(d);
 	ssize_t count = 0;
 
+	if (!df->governor)
+		return -EINVAL;
+
 	mutex_lock(&devfreq_list_lock);
 
 	/*
 	 * The devfreq with immutable governor (e.g., passive) shows
 	 * only own governor.
 	 */
-	if (df->governor && df->governor->immutable) {
+	if (df->governor->immutable) {
 		count = scnprintf(&buf[count], DEVFREQ_NAME_LEN,
 				  "%s ", df->governor_name);
 	/*
@@ -1403,27 +1409,37 @@ static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
 	unsigned long freq;
-	struct devfreq *devfreq = to_devfreq(dev);
+	struct devfreq *df = to_devfreq(dev);
 
-	if (devfreq->profile->get_cur_freq &&
+	if (!df->profile)
-		!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
+		return -EINVAL;
+
+	if (df->profile->get_cur_freq &&
+		!df->profile->get_cur_freq(df->dev.parent, &freq))
 		return sprintf(buf, "%lu\n", freq);
 
-	return sprintf(buf, "%lu\n", devfreq->previous_freq);
+	return sprintf(buf, "%lu\n", df->previous_freq);
 }
 static DEVICE_ATTR_RO(cur_freq);
 
 static ssize_t target_freq_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
+	struct devfreq *df = to_devfreq(dev);
+
+	return sprintf(buf, "%lu\n", df->previous_freq);
 }
 static DEVICE_ATTR_RO(target_freq);
 
 static ssize_t polling_interval_show(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
+	struct devfreq *df = to_devfreq(dev);
+
+	if (!df->profile)
+		return -EINVAL;
+
+	return sprintf(buf, "%d\n", df->profile->polling_ms);
 }
 
 static ssize_t polling_interval_store(struct device *dev,
@@ -1551,6 +1567,9 @@ static ssize_t available_frequencies_show(struct device *d,
 	ssize_t count = 0;
 	int i;
 
+	if (!df->profile)
+		return -EINVAL;
+
 	mutex_lock(&df->lock);
 
 	for (i = 0; i < df->profile->max_state; i++)
@@ -1571,49 +1590,53 @@ static DEVICE_ATTR_RO(available_frequencies);
 static ssize_t trans_stat_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
-	struct devfreq *devfreq = to_devfreq(dev);
+	struct devfreq *df = to_devfreq(dev);
 	ssize_t len;
 	int i, j;
-	unsigned int max_state = devfreq->profile->max_state;
+	unsigned int max_state;
+
+	if (!df->profile)
+		return -EINVAL;
+	max_state = df->profile->max_state;
 
 	if (max_state == 0)
 		return sprintf(buf, "Not Supported.\n");
 
-	mutex_lock(&devfreq->lock);
+	mutex_lock(&df->lock);
-	if (!devfreq->stop_polling &&
+	if (!df->stop_polling &&
-			devfreq_update_status(devfreq, devfreq->previous_freq)) {
+			devfreq_update_status(df, df->previous_freq)) {
-		mutex_unlock(&devfreq->lock);
+		mutex_unlock(&df->lock);
 		return 0;
 	}
-	mutex_unlock(&devfreq->lock);
+	mutex_unlock(&df->lock);
 
 	len = sprintf(buf, "     From  :   To\n");
 	len += sprintf(buf + len, "           :");
 	for (i = 0; i < max_state; i++)
 		len += sprintf(buf + len, "%10lu",
-				devfreq->profile->freq_table[i]);
+				df->profile->freq_table[i]);
 
 	len += sprintf(buf + len, "   time(ms)\n");
 
 	for (i = 0; i < max_state; i++) {
-		if (devfreq->profile->freq_table[i]
+		if (df->profile->freq_table[i]
-					== devfreq->previous_freq) {
+					== df->previous_freq) {
 			len += sprintf(buf + len, "*");
 		} else {
 			len += sprintf(buf + len, " ");
 		}
 		len += sprintf(buf + len, "%10lu:",
-				devfreq->profile->freq_table[i]);
+				df->profile->freq_table[i]);
 		for (j = 0; j < max_state; j++)
 			len += sprintf(buf + len, "%10u",
-				devfreq->stats.trans_table[(i * max_state) + j]);
+				df->stats.trans_table[(i * max_state) + j]);
 
 		len += sprintf(buf + len, "%10llu\n", (u64)
-			jiffies64_to_msecs(devfreq->stats.time_in_state[i]));
+			jiffies64_to_msecs(df->stats.time_in_state[i]));
 	}
 
 	len += sprintf(buf + len, "Total transition : %u\n",
-					devfreq->stats.total_trans);
+					df->stats.total_trans);
 	return len;
 }
 
@@ -1624,6 +1647,9 @@ static ssize_t trans_stat_store(struct device *dev,
 	struct devfreq *df = to_devfreq(dev);
 	int err, value;
 
+	if (!df->profile)
+		return -EINVAL;
+
 	if (df->profile->max_state == 0)
 		return count;