hwmon: (adt7411) Improve locking

Add proper locking for the cached variables. Also get rid of
ref_is_vdd, which became obsolete.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/hwmon/adt7411.c

@@ -48,9 +48,9 @@ static const unsigned short normal_i2c[] = { 0x48, 0x4a, 0x4b, I2C_CLIENT_END };
 
 struct adt7411_data {
 	struct mutex device_lock;	/* for "atomic" device accesses */
+	struct mutex update_lock;
 	unsigned long next_update;
 	int vref_cached;
-	bool ref_is_vdd;
 	struct device *hwmon_dev;
 };
 
@@ -142,18 +142,18 @@ static ssize_t adt7411_show_input(struct device *dev,
 	int val;
 	u8 lsb_reg, lsb_shift;
 
+	mutex_lock(&data->update_lock);
 	if (time_after_eq(jiffies, data->next_update)) {
 		val = i2c_smbus_read_byte_data(client, ADT7411_REG_CFG3);
 		if (val < 0)
-			return val;
-		data->ref_is_vdd = val & ADT7411_CFG3_REF_VDD;
+			goto exit_unlock;
 
-		if (data->ref_is_vdd) {
+		if (val & ADT7411_CFG3_REF_VDD) {
 			val = adt7411_read_10_bit(client,
 					ADT7411_REG_INT_TEMP_VDD_LSB,
 					ADT7411_REG_VDD_MSB, 2);
 			if (val < 0)
-				return val;
+				goto exit_unlock;
 
 			data->vref_cached = val * 7000 / 1024;
 		} else {
@@ -167,9 +167,13 @@ static ssize_t adt7411_show_input(struct device *dev,
 	lsb_shift = 2 * (nr & 0x03);
 	val = adt7411_read_10_bit(client, lsb_reg,
 			ADT7411_REG_EXT_TEMP_AIN1_MSB + nr, lsb_shift);
+	if (val < 0)
+		goto exit_unlock;
 
-	return val < 0 ? val :
-			sprintf(buf, "%u\n", val * data->vref_cached / 1024);
+	val = sprintf(buf, "%u\n", val * data->vref_cached / 1024);
+ exit_unlock:
+	mutex_unlock(&data->update_lock);
+	return val;
 }
 
 static ssize_t adt7411_show_bit(struct device *dev,
@@ -199,7 +203,9 @@ static ssize_t adt7411_set_bit(struct device *dev,
 	ret = adt7411_modify_bit(client, s_attr2->index, s_attr2->nr, flag);
 
 	/* force update */
+	mutex_lock(&data->update_lock);
 	data->next_update = jiffies;
+	mutex_unlock(&data->update_lock);
 
 	return ret < 0 ? ret : count;
 }
@@ -282,6 +288,7 @@ static int __devinit adt7411_probe(struct i2c_client *client,
 
 	i2c_set_clientdata(client, data);
 	mutex_init(&data->device_lock);
+	mutex_init(&data->update_lock);
 
 	ret = adt7411_modify_bit(client, ADT7411_REG_CFG1,
 				 ADT7411_CFG1_START_MONITOR, 1);