[PATCH] hwmon: nct7904: fix error check on register read

[PATCH] hwmon: nct7904: fix error check on register read

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently the return from the call to nct7904_read is being masked
and so and negative error returns are being stripped off and the
error check is always false.  Fix this by checking on err first and
then masking the return value in ret.

Addresses-Coverity: ("Logically dead code")
Fixes: af55ab0b0792 ("hwmon: (nct7904) Add extra sysfs support for fan, voltage and temperature.")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/hwmon/nct7904.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/nct7904.c b/drivers/hwmon/nct7904.c
index dd450dd29ac7..5fa69898674c 100644
--- a/drivers/hwmon/nct7904.c
+++ b/drivers/hwmon/nct7904.c
@@ -928,10 +928,10 @@ static int nct7904_probe(struct i2c_client *client,
 
 	/* Check DTS enable status */
 	if (data->enable_dts) {
-		ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL0_REG) & 0xF;
+		ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL0_REG);
 		if (ret < 0)
 			return ret;
-		data->has_dts = ret;
+		data->has_dts = ret & 0xF;
 		if (data->enable_dts & ENABLE_TSI) {
 			ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL1_REG);
 			if (ret < 0)
-- 
2.20.1

Re: [PATCH] hwmon: nct7904: fix error check on register read

[Guenter Roeck]

Hi Colin,

On 6/6/19 5:27 AM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Currently the return from the call to nct7904_read is being masked
> and so and negative error returns are being stripped off and the
> error check is always false.  Fix this by checking on err first and
> then masking the return value in ret.
> 
> Addresses-Coverity: ("Logically dead code")
> Fixes: af55ab0b0792 ("hwmon: (nct7904) Add extra sysfs support for fan, voltage and temperature.")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Thanks a lot for the patch. The offending patch had several additional
problems (shame on me for sloppy review), so I pulled it from the branch
and asked the author to fix all problems and resubmit.

Guenter

> ---
>   drivers/hwmon/nct7904.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/nct7904.c b/drivers/hwmon/nct7904.c
> index dd450dd29ac7..5fa69898674c 100644
> --- a/drivers/hwmon/nct7904.c
> +++ b/drivers/hwmon/nct7904.c
> @@ -928,10 +928,10 @@ static int nct7904_probe(struct i2c_client *client,
>   
>   	/* Check DTS enable status */
>   	if (data->enable_dts) {
> -		ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL0_REG) & 0xF;
> +		ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL0_REG);
>   		if (ret < 0)
>   			return ret;
> -		data->has_dts = ret;
> +		data->has_dts = ret & 0xF;
>   		if (data->enable_dts & ENABLE_TSI) {
>   			ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL1_REG);
>   			if (ret < 0)
> 

Re: [PATCH] hwmon: nct7904: fix error check on register read

[Colin Ian King]

On 06/06/2019 14:02, Guenter Roeck wrote:
> Hi Colin,
> 
> On 6/6/19 5:27 AM, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Currently the return from the call to nct7904_read is being masked
>> and so and negative error returns are being stripped off and the
>> error check is always false.  Fix this by checking on err first and
>> then masking the return value in ret.
>>
>> Addresses-Coverity: ("Logically dead code")
>> Fixes: af55ab0b0792 ("hwmon: (nct7904) Add extra sysfs support for
>> fan, voltage and temperature.")
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> 
> Thanks a lot for the patch. The offending patch had several additional
> problems (shame on me for sloppy review), so I pulled it from the branch
> and asked the author to fix all problems and resubmit.

Ah, good. I was going to address some other issues too. That saves some
work.

Colin

> 
> Guenter
> 
>> ---
>>   drivers/hwmon/nct7904.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hwmon/nct7904.c b/drivers/hwmon/nct7904.c
>> index dd450dd29ac7..5fa69898674c 100644
>> --- a/drivers/hwmon/nct7904.c
>> +++ b/drivers/hwmon/nct7904.c
>> @@ -928,10 +928,10 @@ static int nct7904_probe(struct i2c_client *client,
>>         /* Check DTS enable status */
>>       if (data->enable_dts) {
>> -        ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL0_REG) & 0xF;
>> +        ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL0_REG);
>>           if (ret < 0)
>>               return ret;
>> -        data->has_dts = ret;
>> +        data->has_dts = ret & 0xF;
>>           if (data->enable_dts & ENABLE_TSI) {
>>               ret = nct7904_read_reg(data, BANK_0, DTS_T_CTRL1_REG);
>>               if (ret < 0)
>>
>