iio: ade7753: avoid uninitialized data

Message ID 1453737174-1959778-1-git-send-email-arnd@arndb.de
State New
Headers show

Commit Message

Arnd Bergmann Jan. 25, 2016, 3:52 p.m.
The ade7753_spi_read_reg_16() will either successfully read a value
from SPI, or return a failure code without delivering data. However,
the ade7753_stop_device() and ade7753_reset() functions use the returned
data without checking for an error condition first. Gcc detects this
as a possible bug and warns about it:

drivers/staging/iio/meter/ade7753.c: In function 'ade7753_remove':
drivers/staging/iio/meter/ade7753.c:348:6: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  val |= BIT(4);  /* AD converters can be turned off */
      ^
drivers/staging/iio/meter/ade7753.c:345:6: note: 'val' was declared here
  u16 val;
      ^
drivers/staging/iio/meter/ade7753.c: In function 'ade7753_probe':
drivers/staging/iio/meter/ade7753.c:222:6: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]

In both cases, we can avoids the warning by checking the return code
before using the data.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/staging/iio/meter/ade7753.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

-- 
2.7.0

Comments

Jonathan Cameron Jan. 30, 2016, 2:22 p.m. | #1
On 25/01/16 15:52, Arnd Bergmann wrote:
> The ade7753_spi_read_reg_16() will either successfully read a value

> from SPI, or return a failure code without delivering data. However,

> the ade7753_stop_device() and ade7753_reset() functions use the returned

> data without checking for an error condition first. Gcc detects this

> as a possible bug and warns about it:

> 

> drivers/staging/iio/meter/ade7753.c: In function 'ade7753_remove':

> drivers/staging/iio/meter/ade7753.c:348:6: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]

>   val |= BIT(4);  /* AD converters can be turned off */

>       ^

> drivers/staging/iio/meter/ade7753.c:345:6: note: 'val' was declared here

>   u16 val;

>       ^

> drivers/staging/iio/meter/ade7753.c: In function 'ade7753_probe':

> drivers/staging/iio/meter/ade7753.c:222:6: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized]

> 

> In both cases, we can avoids the warning by checking the return code

> before using the data.

> 

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks.

Applied to the togreg branch of iio.git - initially pushed out as testing for
the autobuilders to play with it.

Thanks,

Jonathan
> ---

>  drivers/staging/iio/meter/ade7753.c | 12 ++++++++++--

>  1 file changed, 10 insertions(+), 2 deletions(-)

> 

> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c

> index f129039bece3..69287108f793 100644

> --- a/drivers/staging/iio/meter/ade7753.c

> +++ b/drivers/staging/iio/meter/ade7753.c

> @@ -217,8 +217,12 @@ error_ret:

>  static int ade7753_reset(struct device *dev)

>  {

>  	u16 val;

> +	int ret;

> +

> +	ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);

> +	if (ret)

> +		return ret;

>  

> -	ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);

>  	val |= BIT(6); /* Software Chip Reset */

>  

>  	return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);

> @@ -343,8 +347,12 @@ error_ret:

>  static int ade7753_stop_device(struct device *dev)

>  {

>  	u16 val;

> +	int ret;

> +

> +	ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);

> +	if (ret)

> +		return ret;

>  

> -	ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);

>  	val |= BIT(4);  /* AD converters can be turned off */

>  

>  	return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);

>

Patch

diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c
index f129039bece3..69287108f793 100644
--- a/drivers/staging/iio/meter/ade7753.c
+++ b/drivers/staging/iio/meter/ade7753.c
@@ -217,8 +217,12 @@  error_ret:
 static int ade7753_reset(struct device *dev)
 {
 	u16 val;
+	int ret;
+
+	ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
+	if (ret)
+		return ret;
 
-	ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
 	val |= BIT(6); /* Software Chip Reset */
 
 	return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);
@@ -343,8 +347,12 @@  error_ret:
 static int ade7753_stop_device(struct device *dev)
 {
 	u16 val;
+	int ret;
+
+	ret = ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
+	if (ret)
+		return ret;
 
-	ade7753_spi_read_reg_16(dev, ADE7753_MODE, &val);
 	val |= BIT(4);  /* AD converters can be turned off */
 
 	return ade7753_spi_write_reg_16(dev, ADE7753_MODE, val);