linux-kernel - Re: [PATCH] usb: gadget: udc: bdc: Remove unnecessary NULL checks in bdc_req

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Message-ID: <20200221045740.GA43417@ubuntu-m2-xlarge-x86>
Date:   Thu, 20 Feb 2020 21:57:40 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Ashwini Pahuja <ashwini.linux@...il.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] usb: gadget: udc: bdc: Remove unnecessary NULL checks in
 bdc_req_complete

I know it has been a while but ping?

On Tue, Oct 22, 2019 at 05:20:15PM -0700, Nathan Chancellor wrote:
> When building with Clang + -Wtautological-pointer-compare:
> 
> drivers/usb/gadget/udc/bdc/bdc_ep.c:543:28: warning: comparison of
> address of 'req->queue' equal to a null pointer is always false
> [-Wtautological-pointer-compare]
>         if (req == NULL  || &req->queue == NULL || &req->usb_req == NULL)
>                              ~~~~~^~~~~    ~~~~
> drivers/usb/gadget/udc/bdc/bdc_ep.c:543:51: warning: comparison of
> address of 'req->usb_req' equal to a null pointer is always false
> [-Wtautological-pointer-compare]
>         if (req == NULL  || &req->queue == NULL || &req->usb_req == NULL)
>                                                     ~~~~~^~~~~~~    ~~~~
> 2 warnings generated.
> 
> As it notes, these statements will always evaluate to false so remove
> them.
> 
> Fixes: efed421a94e6 ("usb: gadget: Add UDC driver for Broadcom USB3.0 device controller IP BDC")
> Link: https://github.com/ClangBuiltLinux/linux/issues/749
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
> 
> Note: I am not sure if these checks were intended to check if the
> contents of these arrays were NULL or if there should be some other
> checks in lieu of these; I am not familiar with the USB subsystem to
> answer this but I will happily respin the patch if this is not correct.
> 
>  drivers/usb/gadget/udc/bdc/bdc_ep.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/udc/bdc/bdc_ep.c b/drivers/usb/gadget/udc/bdc/bdc_ep.c
> index a4d9b5e1e50e..d49c6dc1082d 100644
> --- a/drivers/usb/gadget/udc/bdc/bdc_ep.c
> +++ b/drivers/usb/gadget/udc/bdc/bdc_ep.c
> @@ -540,7 +540,7 @@ static void bdc_req_complete(struct bdc_ep *ep, struct bdc_req *req,
>  {
>  	struct bdc *bdc = ep->bdc;
>  
> -	if (req == NULL  || &req->queue == NULL || &req->usb_req == NULL)
> +	if (req == NULL)
>  		return;
>  
>  	dev_dbg(bdc->dev, "%s ep:%s status:%d\n", __func__, ep->name, status);
> -- 
> 2.23.0
>