hwmon: sht3x: initialize variable 'ret' in update_interval_write().

[PATCH] hwmon: sht3x: initialize variable 'ret' in update_interval_write().

Posted by Ranganath V N 3 months, 4 weeks ago

fix for the smatch errors:
drivers/hwmon/sht3x.c:606 update_interval_write() error: uninitialized symbol 'ret'.

The warning can occur when both the data->mode and mode which is
derived from get_mode_from_update_interval() are zero.
In this case, no i2c command is sent and ret remains undefined
before reaching the coman return path.

When both data->mode and mode are zero, the device remains in
single shot mode and no configuration change is required.
In such cases, it is correct to treat the operation as successful
without issuing any i2c transfer.

To address this, initialize 'ret' to 'SHT3X_CMD_LENGTH'. this makes
the no-operation path return success while keeping the existing error
to all other paths.

This change removes the smatch errors. Tested by compiling.

Signed-off-by: Ranganath V N <vnranganath.20@gmail.com>
---
 drivers/hwmon/sht3x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c
index 557ad3e7752a..4b52d57eaad8 100644
--- a/drivers/hwmon/sht3x.c
+++ b/drivers/hwmon/sht3x.c
@@ -553,7 +553,7 @@ static int update_interval_read(struct device *dev)
 static int update_interval_write(struct device *dev, int val)
 {
 	u8 mode;
-	int ret;
+	int ret = SHT3X_CMD_LENGTH;
 	const char *command;
 	struct sht3x_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;

---
base-commit: e5f0a698b34ed76002dc5cff3804a61c80233a7a
change-id: 20251012-my_driver_work-77b22c239e99

Best regards,
-- 
Ranganath V N <vnranganath.20@gmail.com>

Re: [PATCH] hwmon: sht3x: initialize variable 'ret' in update_interval_write().

Posted by Guenter Roeck 3 months, 4 weeks ago

On Sun, Oct 12, 2025 at 05:13:27PM +0530, Ranganath V N wrote:
> fix for the smatch errors:
> drivers/hwmon/sht3x.c:606 update_interval_write() error: uninitialized symbol 'ret'.
> 
> The warning can occur when both the data->mode and mode which is
> derived from get_mode_from_update_interval() are zero.
> In this case, no i2c command is sent and ret remains undefined
> before reaching the coman return path.
> 
> When both data->mode and mode are zero, the device remains in
> single shot mode and no configuration change is required.
> In such cases, it is correct to treat the operation as successful
> without issuing any i2c transfer.

Actually, in this case, the code enters

       if (mode == data->mode) {
                mutex_unlock(&data->data_lock);
                return 0;
        }

meaning the problem does not actually exist because 'ret' will be
initialized if either 'mode' or 'data->mode' is != 0. That means
the smatch report is a false positive, and this patch is not required.

Guenter

Re: [PATCH] hwmon: sht3x: initialize variable 'ret' in update_interval_write().

Posted by Guenter Roeck 3 months, 4 weeks ago

On Sun, Oct 12, 2025 at 05:13:27PM +0530, Ranganath V N wrote:
> fix for the smatch errors:
> drivers/hwmon/sht3x.c:606 update_interval_write() error: uninitialized symbol 'ret'.
> 
> The warning can occur when both the data->mode and mode which is
> derived from get_mode_from_update_interval() are zero.
> In this case, no i2c command is sent and ret remains undefined
> before reaching the coman return path.
> 
> When both data->mode and mode are zero, the device remains in
> single shot mode and no configuration change is required.
> In such cases, it is correct to treat the operation as successful
> without issuing any i2c transfer.
> 
> To address this, initialize 'ret' to 'SHT3X_CMD_LENGTH'. this makes
> the no-operation path return success while keeping the existing error
> to all other paths.
> 
> This change removes the smatch errors. Tested by compiling.
> 
> Signed-off-by: Ranganath V N <vnranganath.20@gmail.com>

Applied.

Guenter

> ---
>  drivers/hwmon/sht3x.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> 
> ---
> base-commit: e5f0a698b34ed76002dc5cff3804a61c80233a7a
> change-id: 20251012-my_driver_work-77b22c239e99
> 
> Best regards,
> 
> diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c
> index 557ad3e7752a..4b52d57eaad8 100644
> --- a/drivers/hwmon/sht3x.c
> +++ b/drivers/hwmon/sht3x.c
> @@ -553,7 +553,7 @@ static int update_interval_read(struct device *dev)
>  static int update_interval_write(struct device *dev, int val)
>  {
>  	u8 mode;
> -	int ret;
> +	int ret = SHT3X_CMD_LENGTH;
>  	const char *command;
>  	struct sht3x_data *data = dev_get_drvdata(dev);
>  	struct i2c_client *client = data->client;

Re: [PATCH] hwmon: sht3x: initialize variable 'ret' in update_interval_write().

Posted by Markus Elfring 3 months, 4 weeks ago

…
> To address this, initialize 'ret' to 'SHT3X_CMD_LENGTH'. this makes

                                                           Make?


> the no-operation path return success while keeping the existing error
> to all other paths.
…

See also:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.17#n94

Regards,
Markus