[PATCH v3] staging: iio: meter: add check on return variables

[Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>]

Adds checks on variables that are used to return values. If
the value is less than zero, this indicates that an error
occured and hence a message is printed through dev_err. Labels
have been added too, since the check is done more than once.

Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>
---
v1: added checks on last calls only.
v2: added checks on all calls that return values along with labels.
v3: added changelog that was missed in v2.

 drivers/staging/iio/meter/ade7758_core.c | 35 ++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/iio/meter/ade7758_core.c b/drivers/staging/iio/meter/ade7758_core.c
index 70e96b2..cab392f 100644
--- a/drivers/staging/iio/meter/ade7758_core.c
+++ b/drivers/staging/iio/meter/ade7758_core.c
@@ -303,14 +303,18 @@ static int ade7758_reset(struct device *dev)
 	int ret;
 	u8 val;
 
-	ade7758_spi_read_reg_8(dev,
-			ADE7758_OPMODE,
-			&val);
+	ret = ade7758_spi_read_reg_8(dev, ADE7758_OPMODE, &val);
+	if (ret < 0) {
+		dev_err(dev, "failed to read from device");
+		goto error_ret;
+	}
 	val |= 1 << 6; /* Software Chip Reset */
-	ret = ade7758_spi_write_reg_8(dev,
-			ADE7758_OPMODE,
-			val);
-
+	ret = ade7758_spi_write_reg_8(dev, ADE7758_OPMODE, val);
+	if (ret < 0) {
+		dev_err(dev, "failed to reset device");
+		goto error_ret;
+	}
+error_ret:
 	return ret;
 }
 
@@ -444,14 +448,19 @@ static int ade7758_stop_device(struct device *dev)
 	int ret;
 	u8 val;
 
-	ade7758_spi_read_reg_8(dev,
-			ADE7758_OPMODE,
-			&val);
+	ret = ade7758_spi_read_reg_8(dev, ADE7758_OPMODE, &val);
+	if (ret < 0) {
+		dev_err(dev, "failed to read from device");
+		goto error_ret;
+	}
 	val |= 7 << 3;  /* ADE7758 powered down */
-	ret = ade7758_spi_write_reg_8(dev,
-			ADE7758_OPMODE,
-			val);
+	ret = ade7758_spi_write_reg_8(dev, ADE7758_OPMODE, val);
+	if (ret < 0) {
+		dev_err(dev, "failed to stop device");
+		goto error_ret;
+	}
 
+error_ret:
 	return ret;
 }
 
-- 
1.9.3


-- 
Kind Regards,
Aya Saif El-yazal Mahfouz