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

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Date: Thu, 4 Jan 2024 14:15:59 +0100
From: Christian Marangi <ansuelsmth@...il.com>
To: Simon Horman <horms@...nel.org>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [net-next PATCH v3 2/4] net: phy: at803x: refactor qca808x cable
 test get status function

On Thu, Jan 04, 2024 at 01:03:37PM +0000, Simon Horman wrote:
> 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 <ansuelsmth@...il.com>
> > ---
> >  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.
>

In theory it would trigger a warning for the switch case not handled?

But yes I will add a default case.

> > +
> > +	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;
> >  
> 
> ...

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