netdev - Re: [PATCH] net: ethernet: mtk_eth_soc: fix error checking in mtk_mac

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Date:   Mon, 10 Jan 2022 05:43:00 -0800
From:   Tom Rix <trix@...hat.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     nbd@....name, john@...ozen.org, sean.wang@...iatek.com,
        Mark-MC.Lee@...iatek.com, davem@...emloft.net,
        matthias.bgg@...il.com, linux@...linux.org.uk, nathan@...nel.org,
        ndesaulniers@...gle.com, opensource@...rst.com,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: Re: [PATCH] net: ethernet: mtk_eth_soc: fix error checking in
 mtk_mac_config()


On 1/9/22 4:43 PM, Jakub Kicinski wrote:
> On Sat,  8 Jan 2022 07:50:03 -0800 trix@...hat.com wrote:
>> From: Tom Rix <trix@...hat.com>
>>
>> Clang static analysis reports this problem
>> mtk_eth_soc.c:394:7: warning: Branch condition evaluates
>>    to a garbage value
>>                  if (err)
>>                      ^~~
>>
>> err is not initialized and only conditionally set.
>> Check err consistently with the rest of mtk_mac_config(),
>> after even possible setting.
>>
>> Fixes: 7e538372694b ("net: ethernet: mediatek: Re-add support SGMII")
>> Signed-off-by: Tom Rix <trix@...hat.com>
>> ---
>>   drivers/net/ethernet/mediatek/mtk_eth_soc.c | 12 +++++++-----
>>   1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> index b67b4323cff08..a27e548488584 100644
>> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>> @@ -385,14 +385,16 @@ static void mtk_mac_config(struct phylink_config *config, unsigned int mode,
>>   		       0 : mac->id;
>>   
>>   		/* Setup SGMIISYS with the determined property */
>> -		if (state->interface != PHY_INTERFACE_MODE_SGMII)
>> +		if (state->interface != PHY_INTERFACE_MODE_SGMII) {
>>   			err = mtk_sgmii_setup_mode_force(eth->sgmii, sid,
>>   							 state);
>> -		else if (phylink_autoneg_inband(mode))
>> +			if (err)
>> +				goto init_err;
>> +		} else if (phylink_autoneg_inband(mode)) {
>>   			err = mtk_sgmii_setup_mode_an(eth->sgmii, sid);
>> -
>> -		if (err)
>> -			goto init_err;
>> +			if (err)
>> +				goto init_err;
>> +		}
>>   
>>   		regmap_update_bits(eth->ethsys, ETHSYS_SYSCFG0,
>>   				   SYSCFG0_SGMII_MASK, val);
> Why not init err to 0 before the if or add an else err = 0; branch?

This is the way I would have preferred to do it but the function's 
existing error handling does it this way.

I'll respin the patch.

Tom


>