Subject: Re: [net-next PATCH v3 2/4] net: phy: at803x: refactor qca808x cable test get status function

From: Simon Horman <[email-masked]>
Date: Thu, 4 Jan 2024 13:03:37 +0000

On Wed, Jan 03, 2024 at 01:46:33PM +0100, Christian Marangi wrote:
> Refactor qca808x cable test get status function to remove code
> duplication and clean things up.
> 
> The same logic is applied to each pair hence it can be generalized and
> moved to a common function.
> 
> Signed-off-by: Christian Marangi <[email-masked]>
> ---
>  drivers/net/phy/at803x.c | 65 +++++++++++++++++++++-------------------
>  1 file changed, 34 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
> index acf483fa0887..b87293ee736c 100644
> --- a/drivers/net/phy/at803x.c
> +++ b/drivers/net/phy/at803x.c
> @@ -2037,10 +2037,39 @@ static int qca808x_cable_test_start(struct phy_device *phydev)
>  	return 0;
>  }
>  
> +static void qca808x_cable_test_get_pair_status(struct phy_device *phydev, u8 pair,
> +					       u16 status)
> +{
> +	u16 pair_code;
> +	int length;
> +
> +	switch (pair) {
> +	case ETHTOOL_A_CABLE_PAIR_A:
> +		pair_code = FIELD_GET(QCA808X_CDT_CODE_PAIR_A, status);
> +		break;
> +	case ETHTOOL_A_CABLE_PAIR_B:
> +		pair_code = FIELD_GET(QCA808X_CDT_CODE_PAIR_B, status);
> +		break;
> +	case ETHTOOL_A_CABLE_PAIR_C:
> +		pair_code = FIELD_GET(QCA808X_CDT_CODE_PAIR_C, status);
> +		break;
> +	case ETHTOOL_A_CABLE_PAIR_D:
> +		pair_code = FIELD_GET(QCA808X_CDT_CODE_PAIR_D, status);
> +		break;
> +	}

Hi Christian,

I don't think this can actually happen given current usage,
but if pair doesn't match one of the cases above,
then pair_code is used uninitialised below.

Flagged by Smatch.

> +
> +	ethnl_cable_test_result(phydev, pair,
> +				qca808x_cable_test_result_trans(pair_code));
> +
> +	if (qca808x_cdt_fault_length_valid(pair_code)) {
> +		length = qca808x_cdt_fault_length(phydev, pair);
> +		ethnl_cable_test_fault_length(phydev, pair, length);
> +	}
> +}
> +
>  static int qca808x_cable_test_get_status(struct phy_device *phydev, bool *finished)
>  {
>  	int ret, val;
> -	int pair_a, pair_b, pair_c, pair_d;
>  
>  	*finished = false;
>  

...