[PATCH v2 2/5] iio: light: tcs3472: convert remaining locking to guard(mutex)

[Aldo Conte <aldocontelk@gmail.com>]

Convert the locking in tcs3472_read_event(), tcs3472_write_event(),
tcs3472_read_event_config(), tcs3472_write_event_config(),
tcs3472_powerdown() and tcs3472_resume() to use guard(mutex)
instead of explicit mutex_lock()/mutex_unlock() pairs.

This avoids manual unlock calls on each return path, drops the goto
in tcs3472_write_event(), and removes 'ret' variables only needed to
return after the unlock.

No functional change.

Suggested-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Aldo Conte <aldocontelk@gmail.com>
---
v2:
(Suggested by Andy)
- Moved earlier in the series to avoid introducing manual locking in the devm
  patch that would then be converted here.
- Dropped "found by code inspection" (this is a cleanup, not a bug)
- Test details moved to cover letter

 drivers/iio/light/tcs3472.c | 59 +++++++++++++------------------------
 1 file changed, 21 insertions(+), 38 deletions(-)

diff --git a/drivers/iio/light/tcs3472.c b/drivers/iio/light/tcs3472.c
index 9b0f64cd9c50..4fd4fd74d0d6 100644
--- a/drivers/iio/light/tcs3472.c
+++ b/drivers/iio/light/tcs3472.c
@@ -13,6 +13,7 @@
  * TODO: wait time
  */
 
+#include <linux/cleanup.h>
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
@@ -220,32 +221,24 @@ static int tcs3472_read_event(struct iio_dev *indio_dev,
 	int *val2)
 {
 	struct tcs3472_data *data = iio_priv(indio_dev);
-	int ret;
 	unsigned int period;
 
-	mutex_lock(&data->lock);
+	guard(mutex)(&data->lock);
 
 	switch (info) {
 	case IIO_EV_INFO_VALUE:
 		*val = (dir == IIO_EV_DIR_RISING) ?
 			data->high_thresh : data->low_thresh;
-		ret = IIO_VAL_INT;
-		break;
+		return IIO_VAL_INT;
 	case IIO_EV_INFO_PERIOD:
 		period = (256 - data->atime) * 2400 *
 			tcs3472_intr_pers[data->apers];
 		*val = period / USEC_PER_SEC;
 		*val2 = period % USEC_PER_SEC;
-		ret = IIO_VAL_INT_PLUS_MICRO;
-		break;
+		return IIO_VAL_INT_PLUS_MICRO;
 	default:
-		ret = -EINVAL;
-		break;
+		return -EINVAL;
 	}
-
-	mutex_unlock(&data->lock);
-
-	return ret;
 }
 
 static int tcs3472_write_event(struct iio_dev *indio_dev,
@@ -259,7 +252,8 @@ static int tcs3472_write_event(struct iio_dev *indio_dev,
 	int period;
 	int i;
 
-	mutex_lock(&data->lock);
+	guard(mutex)(&data->lock);
+
 	switch (info) {
 	case IIO_EV_INFO_VALUE:
 		switch (dir) {
@@ -270,18 +264,18 @@ static int tcs3472_write_event(struct iio_dev *indio_dev,
 			command = TCS3472_AILT;
 			break;
 		default:
-			ret = -EINVAL;
-			goto error;
+			return -EINVAL;
 		}
 		ret = i2c_smbus_write_word_data(data->client, command, val);
 		if (ret)
-			goto error;
+			return ret;
 
 		if (dir == IIO_EV_DIR_RISING)
 			data->high_thresh = val;
 		else
 			data->low_thresh = val;
-		break;
+
+		return 0;
 	case IIO_EV_INFO_PERIOD:
 		period = val * USEC_PER_SEC + val2;
 		for (i = 1; i < ARRAY_SIZE(tcs3472_intr_pers) - 1; i++) {
@@ -291,18 +285,14 @@ static int tcs3472_write_event(struct iio_dev *indio_dev,
 		}
 		ret = i2c_smbus_write_byte_data(data->client, TCS3472_PERS, i);
 		if (ret)
-			goto error;
+			return ret;
 
 		data->apers = i;
-		break;
+
+		return 0;
 	default:
-		ret = -EINVAL;
-		break;
+		return -EINVAL;
 	}
-error:
-	mutex_unlock(&data->lock);
-
-	return ret;
 }
 
 static int tcs3472_read_event_config(struct iio_dev *indio_dev,
@@ -310,13 +300,10 @@ static int tcs3472_read_event_config(struct iio_dev *indio_dev,
 	enum iio_event_direction dir)
 {
 	struct tcs3472_data *data = iio_priv(indio_dev);
-	int ret;
 
-	mutex_lock(&data->lock);
-	ret = !!(data->enable & TCS3472_ENABLE_AIEN);
-	mutex_unlock(&data->lock);
+	guard(mutex)(&data->lock);
 
-	return ret;
+	return !!(data->enable & TCS3472_ENABLE_AIEN);
 }
 
 static int tcs3472_write_event_config(struct iio_dev *indio_dev,
@@ -327,7 +314,7 @@ static int tcs3472_write_event_config(struct iio_dev *indio_dev,
 	int ret = 0;
 	u8 enable_old;
 
-	mutex_lock(&data->lock);
+	guard(mutex)(&data->lock);
 
 	enable_old = data->enable;
 
@@ -342,7 +329,6 @@ static int tcs3472_write_event_config(struct iio_dev *indio_dev,
 		if (ret)
 			data->enable = enable_old;
 	}
-	mutex_unlock(&data->lock);
 
 	return ret;
 }
@@ -379,6 +365,7 @@ static irqreturn_t tcs3472_trigger_handler(int irq, void *p)
 	} scan = { };
 
 	int ret = tcs3472_req_data(data);
+
 	if (ret < 0)
 		goto done;
 
@@ -544,15 +531,13 @@ static int tcs3472_powerdown(struct tcs3472_data *data)
 	int ret;
 	u8 enable_mask = TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON;
 
-	mutex_lock(&data->lock);
+	guard(mutex)(&data->lock);
 
 	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
 		data->enable & ~enable_mask);
 	if (!ret)
 		data->enable &= ~enable_mask;
 
-	mutex_unlock(&data->lock);
-
 	return ret;
 }
 
@@ -581,15 +566,13 @@ static int tcs3472_resume(struct device *dev)
 	int ret;
 	u8 enable_mask = TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON;
 
-	mutex_lock(&data->lock);
+	guard(mutex)(&data->lock);
 
 	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
 		data->enable | enable_mask);
 	if (!ret)
 		data->enable |= enable_mask;
 
-	mutex_unlock(&data->lock);
-
 	return ret;
 }
 
-- 
2.54.0