[PATCH v4] iio: adc: mcp3911: simplify code with guard macro

[Marcus Folkesson <marcus.folkesson@gmail.com>]

Use the guard(mutex) macro for handle mutex lock/unlocks.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---
Changes in v4:
- Remove unreachable breaks
- Link to v3: https://lore.kernel.org/r/20231205-mcp3911-guard-v3-1-df83e956d1e9@gmail.com

Changes in v3:
- Return early in good paths as well
- Rebase against master
- Link to v2: https://lore.kernel.org/r/20231127-mcp3911-guard-v2-1-9462630dca1e@gmail.com

Changes in v2:
- Return directly instead of goto label
- Link to v1: https://lore.kernel.org/r/20231125-mcp3911-guard-v1-1-2748d16a3f3f@gmail.com
---
 drivers/iio/adc/mcp3911.c | 55 +++++++++++++----------------------------------
 1 file changed, 15 insertions(+), 40 deletions(-)

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index d864558bc087..dfcb6cb7570f 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -7,6 +7,7 @@
  */
 #include <linux/bitfield.h>
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>
@@ -318,44 +319,28 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
 	struct mcp3911 *adc = iio_priv(indio_dev);
 	int ret = -EINVAL;
 
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		ret = mcp3911_read(adc,
 				   MCP3911_CHANNEL(channel->channel), val, 3);
 		if (ret)
-			goto out;
+			return ret;
 
 		*val = sign_extend32(*val, 23);
-
-		ret = IIO_VAL_INT;
-		break;
-
+		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_OFFSET:
-
 		ret = adc->chip->get_offset(adc, channel->channel, val);
-		if (ret)
-			goto out;
-
-		ret = IIO_VAL_INT;
-		break;
+		return (ret) ? ret : IIO_VAL_INT;
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		ret = adc->chip->get_osr(adc, val);
-		if (ret)
-			goto out;
-
-		ret = IIO_VAL_INT;
-		break;
-
+		return (ret) ? ret : IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];
 		*val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];
-		ret = IIO_VAL_INT_PLUS_NANO;
-		break;
+		return IIO_VAL_INT_PLUS_NANO;
 	}
 
-out:
-	mutex_unlock(&adc->lock);
 	return ret;
 }
 
@@ -364,9 +349,8 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
 			     int val2, long mask)
 {
 	struct mcp3911 *adc = iio_priv(indio_dev);
-	int ret = -EINVAL;
 
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
 		for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
@@ -374,32 +358,24 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
 			    val2 == mcp3911_scale_table[i][1]) {
 
 				adc->gain[channel->channel] = BIT(i);
-				ret = adc->chip->set_scale(adc, channel->channel, i);
+				return adc->chip->set_scale(adc, channel->channel, i);
 			}
 		}
 		break;
 	case IIO_CHAN_INFO_OFFSET:
-		if (val2 != 0) {
-			ret = -EINVAL;
-			goto out;
-		}
-
-		ret = adc->chip->set_offset(adc, channel->channel, val);
-		break;
+		if (val2 != 0)
+			return -EINVAL;
 
+		return adc->chip->set_offset(adc, channel->channel, val);
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		for (int i = 0; i < ARRAY_SIZE(mcp3911_osr_table); i++) {
 			if (val == mcp3911_osr_table[i]) {
-				ret = adc->chip->set_osr(adc, i);
-				break;
+				return adc->chip->set_osr(adc, i);
 			}
 		}
 		break;
 	}
-
-out:
-	mutex_unlock(&adc->lock);
-	return ret;
+	return -EINVAL;
 }
 
 static int mcp3911_calc_scale_table(struct mcp3911 *adc)
@@ -532,7 +508,7 @@ static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
 	int i = 0;
 	int ret;
 
-	mutex_lock(&adc->lock);
+	guard(mutex)(&adc->lock);
 	adc->tx_buf = MCP3911_REG_READ(MCP3911_CHANNEL(0), adc->dev_addr);
 	ret = spi_sync_transfer(adc->spi, xfer, ARRAY_SIZE(xfer));
 	if (ret < 0) {
@@ -549,7 +525,6 @@ static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
 	iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
 					   iio_get_time_ns(indio_dev));
 out:
-	mutex_unlock(&adc->lock);
 	iio_trigger_notify_done(indio_dev->trig);
 
 	return IRQ_HANDLED;

---
base-commit: 33cc938e65a98f1d29d0a18403dbbee050dcad9a
change-id: 20231125-mcp3911-guard-866591e2c947

Best regards,
-- 
Marcus Folkesson <marcus.folkesson@gmail.com>