netdev - Re: [PATCH v1] drivers/net/ethernet: check return value of e1e

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Date:   Tue, 23 Aug 2022 08:19:39 -0700
From:   Jesse Brandeburg <jesse.brandeburg@...el.com>
To:     lily <floridsleeves@...il.com>, <intel-wired-lan@...ts.osuosl.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <anthony.l.nguyen@...el.com>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>
Subject: Re: [PATCH v1] drivers/net/ethernet: check return value of e1e_rphy()

On 8/22/2022 11:02 PM, lily wrote:
> e1e_rphy() could return error value, which need to be checked.

Thanks for having a look at the e1000e driver. Was there some bug you 
found or is this just a fix based on a tool or observation?

If a tool was used, what tool?

For networking patches please follow the guidance at 
https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html


> Signed-off-by: Li Zhong <floridsleeves@...il.com>
> ---
>   drivers/net/ethernet/intel/e1000e/phy.c | 14 +++++++++++---
>   1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000e/phy.c b/drivers/net/ethernet/intel/e1000e/phy.c
> index fd07c3679bb1..15ac302fdee0 100644
> --- a/drivers/net/ethernet/intel/e1000e/phy.c
> +++ b/drivers/net/ethernet/intel/e1000e/phy.c
> @@ -2697,9 +2697,12 @@ static s32 e1000_access_phy_wakeup_reg_bm(struct e1000_hw *hw, u32 offset,
>   void e1000_power_up_phy_copper(struct e1000_hw *hw)
>   {
>   	u16 mii_reg = 0;
> +	int ret;
>   
>   	/* The PHY will retain its settings across a power down/up cycle */
> -	e1e_rphy(hw, MII_BMCR, &mii_reg);
> +	ret = e1e_rphy(hw, MII_BMCR, &mii_reg);
> +	if (ret)
> +		return ret;

Can't return value to a void declared function, did you even compile 
test this?

Maybe it should be like:
     if (ret) {
	// this is psuedo code
         dev_warn(..., "PHY read failed during power up\n");
         return;
     }

>   	mii_reg &= ~BMCR_PDOWN;
>   	e1e_wphy(hw, MII_BMCR, mii_reg);
>   }
> @@ -2715,9 +2718,12 @@ void e1000_power_up_phy_copper(struct e1000_hw *hw)
>   void e1000_power_down_phy_copper(struct e1000_hw *hw)
>   {
>   	u16 mii_reg = 0;
> +	int ret;
>   
>   	/* The PHY will retain its settings across a power down/up cycle */
> -	e1e_rphy(hw, MII_BMCR, &mii_reg);
> +	ret = e1e_rphy(hw, MII_BMCR, &mii_reg);
> +	if (ret)
> +		return ret;

same here.

>   	mii_reg |= BMCR_PDOWN;
>   	e1e_wphy(hw, MII_BMCR, mii_reg);
>   	usleep_range(1000, 2000);
> @@ -3037,7 +3043,9 @@ s32 e1000_link_stall_workaround_hv(struct e1000_hw *hw)
>   		return 0;
>   
>   	/* Do not apply workaround if in PHY loopback bit 14 set */
> -	e1e_rphy(hw, MII_BMCR, &data);
> +	ret_val = e1e_rphy(hw, MII_BMCR, &data);
> +	if (ret_val)
> +		return ret_val;
>   	if (data & BMCR_LOOPBACK)
>   		return 0;
>   

Did any of the callers of the above function care about the return code 
being an error value? This has been like this for a long time...