[PATCH v3] iio: accel: bmc150: use guard(mutex) for mutex handling

[Gabriel Rondon]

Replace manual mutex_lock()/mutex_unlock() pairs with guard(mutex)
and scoped_guard() from cleanup.h. This simplifies error paths by
removing the need for explicit unlock calls before returning.

Most converted functions hold the lock for their entire body, so
guard(mutex) applies directly. bmc150_accel_trigger_handler() only
holds the lock around a single register read, so scoped_guard() is
used there to keep the lock scope unchanged.

Signed-off-by: Gabriel Rondon <grondon@xxxxxxxxx>
Reviewed-by: Stepan Ionichev <sozdayvek@xxxxxxxxx>
---
Changes since v2:
 - bmc150_accel_get_fifo_state(): normalize fifo_mode to 0/1 in the
   sysfs output (data->fifo_mode ? 1 : 0). v2 dropped the bool
   intermediate and printed the raw mode value, which would emit the
   FIFO mode bit (0x40) as 64 instead of 0/1. The original 0/1 output
   is preserved. Reported by Jonathan Cameron.
 - Collected Reviewed-by from Stepan Ionichev.

Changes since v1:
 - Drop the verbose list of converted functions from the commit message.
 - bmc150_accel_get_temp(): keep the original declaration order; no
   unrelated line movement.
 - bmc150_accel_get_axis(): convert to guard(mutex) as well, the only
   code outside the old lock scope was a trivial error check.
 - bmc150_accel_trigger_handler(): use scoped_guard() so that no manual
   mutex_lock()/mutex_unlock() pairs are left behind.
 - bmc150_accel_get_fifo_watermark() / bmc150_accel_get_fifo_state():
   drop the intermediate variable and return directly.

 drivers/iio/accel/bmc150-accel-core.c | 68 ++++++++-------------------
 1 file changed, 20 insertions(+), 48 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c
index 2398eb7e12cd..e8c40aa0375d 100644
--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -7,6 +7,7 @@
 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
+#include <linux/cleanup.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
@@ -600,18 +601,15 @@ static int bmc150_accel_get_temp(struct bmc150_accel_data *data, int *val)
 	int ret;
 	unsigned int value;
 
-	mutex_lock(&data->mutex);
+	guard(mutex)(&data->mutex);
 
 	ret = regmap_read(data->regmap, BMC150_ACCEL_REG_TEMP, &value);
 	if (ret < 0) {
 		dev_err(dev, "Error reading reg_temp\n");
-		mutex_unlock(&data->mutex);
 		return ret;
 	}
 	*val = sign_extend32(value, 7);
 
-	mutex_unlock(&data->mutex);
-
 	return IIO_VAL_INT;
 }
 
@@ -624,25 +622,21 @@ static int bmc150_accel_get_axis(struct bmc150_accel_data *data,
 	int axis = chan->scan_index;
 	__le16 raw_val;
 
-	mutex_lock(&data->mutex);
+	guard(mutex)(&data->mutex);
 	ret = bmc150_accel_set_power_state(data, true);
-	if (ret < 0) {
-		mutex_unlock(&data->mutex);
+	if (ret < 0)
 		return ret;
-	}
 
 	ret = regmap_bulk_read(data->regmap, BMC150_ACCEL_AXIS_TO_REG(axis),
 			       &raw_val, sizeof(raw_val));
 	if (ret < 0) {
 		dev_err(dev, "Error reading axis %d\n", axis);
 		bmc150_accel_set_power_state(data, false);
-		mutex_unlock(&data->mutex);
 		return ret;
 	}
 	*val = sign_extend32(le16_to_cpu(raw_val) >> chan->scan_type.shift,
 			     chan->scan_type.realbits - 1);
 	ret = bmc150_accel_set_power_state(data, false);
-	mutex_unlock(&data->mutex);
 	if (ret < 0)
 		return ret;
 
@@ -810,17 +804,14 @@ static int bmc150_accel_write_event_config(struct iio_dev *indio_dev,
 	if (state == data->ev_enable_state)
 		return 0;
 
-	mutex_lock(&data->mutex);
+	guard(mutex)(&data->mutex);
 
 	ret = bmc150_accel_set_interrupt(data, BMC150_ACCEL_INT_ANY_MOTION,
 					 state);
-	if (ret < 0) {
-		mutex_unlock(&data->mutex);
+	if (ret < 0)
 		return ret;
-	}
 
 	data->ev_enable_state = state;
-	mutex_unlock(&data->mutex);
 
 	return 0;
 }
@@ -845,13 +836,10 @@ static ssize_t bmc150_accel_get_fifo_watermark(struct device *dev,
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct bmc150_accel_data *data = iio_priv(indio_dev);
-	int wm;
 
-	mutex_lock(&data->mutex);
-	wm = data->watermark;
-	mutex_unlock(&data->mutex);
+	guard(mutex)(&data->mutex);
 
-	return sysfs_emit(buf, "%d\n", wm);
+	return sysfs_emit(buf, "%d\n", data->watermark);
 }
 
 static ssize_t bmc150_accel_get_fifo_state(struct device *dev,
@@ -860,13 +848,10 @@ static ssize_t bmc150_accel_get_fifo_state(struct device *dev,
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct bmc150_accel_data *data = iio_priv(indio_dev);
-	bool state;
 
-	mutex_lock(&data->mutex);
-	state = data->fifo_mode;
-	mutex_unlock(&data->mutex);
+	guard(mutex)(&data->mutex);
 
-	return sysfs_emit(buf, "%d\n", state);
+	return sysfs_emit(buf, "%d\n", data->fifo_mode ? 1 : 0);
 }
 
 static const struct iio_mount_matrix *
@@ -906,9 +891,8 @@ static int bmc150_accel_set_watermark(struct iio_dev *indio_dev, unsigned val)
 	if (val > BMC150_ACCEL_FIFO_LENGTH)
 		val = BMC150_ACCEL_FIFO_LENGTH;
 
-	mutex_lock(&data->mutex);
+	guard(mutex)(&data->mutex);
 	data->watermark = val;
-	mutex_unlock(&data->mutex);
 
 	return 0;
 }
@@ -1021,13 +1005,10 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev,
 static int bmc150_accel_fifo_flush(struct iio_dev *indio_dev, unsigned samples)
 {
 	struct bmc150_accel_data *data = iio_priv(indio_dev);
-	int ret;
 
-	mutex_lock(&data->mutex);
-	ret = __bmc150_accel_fifo_flush(indio_dev, samples, false);
-	mutex_unlock(&data->mutex);
+	guard(mutex)(&data->mutex);
 
-	return ret;
+	return __bmc150_accel_fifo_flush(indio_dev, samples, false);
 }
 
 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
@@ -1187,10 +1168,9 @@ static irqreturn_t bmc150_accel_trigger_handler(int irq, void *p)
 	struct bmc150_accel_data *data = iio_priv(indio_dev);
 	int ret;
 
-	mutex_lock(&data->mutex);
-	ret = regmap_bulk_read(data->regmap, BMC150_ACCEL_REG_XOUT_L,
-			       data->buffer, AXIS_MAX * 2);
-	mutex_unlock(&data->mutex);
+	scoped_guard(mutex, &data->mutex)
+		ret = regmap_bulk_read(data->regmap, BMC150_ACCEL_REG_XOUT_L,
+				       data->buffer, AXIS_MAX * 2);
 	if (ret < 0)
 		goto err_read;
 
@@ -1230,31 +1210,23 @@ static int bmc150_accel_trigger_set_state(struct iio_trigger *trig,
 	struct bmc150_accel_data *data = t->data;
 	int ret;
 
-	mutex_lock(&data->mutex);
+	guard(mutex)(&data->mutex);
 
-	if (t->enabled == state) {
-		mutex_unlock(&data->mutex);
+	if (t->enabled == state)
 		return 0;
-	}
 
 	if (t->setup) {
 		ret = t->setup(t, state);
-		if (ret < 0) {
-			mutex_unlock(&data->mutex);
+		if (ret < 0)
 			return ret;
-		}
 	}
 
 	ret = bmc150_accel_set_interrupt(data, t->intr, state);
-	if (ret < 0) {
-		mutex_unlock(&data->mutex);
+	if (ret < 0)
 		return ret;
-	}
 
 	t->enabled = state;
 
-	mutex_unlock(&data->mutex);
-
 	return ret;
 }
 
-- 
2.33.0