linux-kernel - Re: [PATCH] net: phy: initialize ge and fe variables

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Message-ID: <20210531222246.47508d84@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
Date:   Mon, 31 May 2021 22:22:46 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     trix@...hat.com
Cc:     pgwipeout@...il.com, andrew@...n.ch, hkallweit1@...il.com,
        linux@...linux.org.uk, davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: initialize ge and fe variables

On Sun, 30 May 2021 12:29:43 -0700 trix@...hat.com wrote:
> From: Tom Rix <trix@...hat.com>
> 
> Static analysis reports this issue
> /motorcomm.c:83:2: warning: variable 'ge' is used uninitialized
>   whenever switch default is taken [-Wsometimes-uninitialized]
>         default: /* leave everything alone in other modes */
>         ^~~~~~~
> drivers/net/phy/motorcomm.c:87:85: note: uninitialized use
>   occurs here
>         ret = __phy_modify(phydev, YT8511_PAGE,
> 	  (YT8511_DELAY_RX | YT8511_DELAY_GE_TX_EN), ge);
>                                                      ^~
> 
> __phy_modify() calls __mdiobus_modify_changed(.., mask, set)
> 
> 	new = (ret & ~mask) | set;
> 	if (new == ret)
> 		return 0;
> 
> 	ret = __mdiobus_write(bus, addr, regnum, new);
> 
> Since 'ge/set' is or-ed in, it is safe to initialize it to 0
> 
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  drivers/net/phy/motorcomm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
> index 796b68f4b499..53b2906c54ef 100644
> --- a/drivers/net/phy/motorcomm.c
> +++ b/drivers/net/phy/motorcomm.c
> @@ -50,7 +50,7 @@ static int yt8511_write_page(struct phy_device *phydev, int page)
>  
>  static int yt8511_config_init(struct phy_device *phydev)
>  {
> -	unsigned int ge, fe;
> +	unsigned int ge = 0, fe = 0;
>  	int ret, oldpage;
>  
>  	/* set clock mode to 125mhz */

I believe this was fixed by just-applied commit 0cc8bddb5b06 ("net: phy:
abort loading yt8511 driver in unsupported modes").