linux-kernel - Re: [PATCH] usb: dwc3: meson-g12a: Don't use ret uninitialized in dwc3_meson_g12a_otg

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Date:   Wed, 19 Feb 2020 15:14:06 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        Felipe Balbi <balbi@...nel.org>
Cc:     Hanjie Lin <hanjie.lin@...ogic.com>,
        kbuild test robot <lkp@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yue Wang <yue.wang@...ogic.com>,
        clang-built-linux@...glegroups.com,
        Kevin Hilman <khilman@...libre.com>,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] usb: dwc3: meson-g12a: Don't use ret uninitialized in
 dwc3_meson_g12a_otg_init

On 10/02/2020 23:58, Nathan Chancellor wrote:
> Clang warns:
> 
> ../drivers/usb/dwc3/dwc3-meson-g12a.c:421:6: warning: variable 'ret' is
> used uninitialized whenever 'if' condition is false
> [-Wsometimes-uninitialized]
>         if (priv->otg_mode == USB_DR_MODE_OTG) {
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/usb/dwc3/dwc3-meson-g12a.c:455:9: note: uninitialized use
> occurs here
>         return ret;
>                ^~~
> ../drivers/usb/dwc3/dwc3-meson-g12a.c:421:2: note: remove the 'if' if
> its condition is always true
>         if (priv->otg_mode == USB_DR_MODE_OTG) {
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/usb/dwc3/dwc3-meson-g12a.c:415:9: note: initialize the
> variable 'ret' to silence this warning
>         int ret, irq;
>                ^
>                 = 0
> 1 warning generated.
> 
> It is not wrong, ret is only used when that if statement is true. Just
> directly return 0 at the end to avoid this.
> 
> Fixes: 729149c53f04 ("usb: dwc3: Add Amlogic A1 DWC3 glue")
> Reported-by: kbuild test robot <lkp@...el.com>
> Link: https://groups.google.com/d/msg/clang-built-linux/w5iBENco_m4/PPuXreAxBQAJ
> Link: https://github.com/ClangBuiltLinux/linux/issues/869
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
> 
> Note: This patch is against Felipe's testing/next branch.
> 
>  drivers/usb/dwc3/dwc3-meson-g12a.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-meson-g12a.c b/drivers/usb/dwc3/dwc3-meson-g12a.c
> index 70d24b98fcad..902553f39889 100644
> --- a/drivers/usb/dwc3/dwc3-meson-g12a.c
> +++ b/drivers/usb/dwc3/dwc3-meson-g12a.c
> @@ -452,7 +452,7 @@ static int dwc3_meson_g12a_otg_init(struct platform_device *pdev,
>  	if (IS_ERR(priv->role_switch))
>  		dev_warn(dev, "Unable to register Role Switch\n");
>  
> -	return ret;
> +	return 0;
>  }
>  
>  static int dwc3_meson_g12a_probe(struct platform_device *pdev)
> 

Acked-by: Neil Armstrong <narmstrong@...libre.com>