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

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Date:   Thu, 6 Jun 2019 06:02:07 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Colin King <colin.king@...onical.com>,
        "amy . shih" <amy.shih@...antech.com.tw>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: nct7904: fix error check on register read

Hi Colin,

On 6/6/19 5:27 AM, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.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@...onical.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)
>