linux-kernel - Re: [PATCH] staging: atomisp: Fix fallthrough keyword warning

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Message-ID: <20200831134021.GV8299@kadam>
Date:   Mon, 31 Aug 2020 16:40:21 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Cengiz Can <cengiz@...nel.wtf>
Cc:     "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org
Subject: Re: [PATCH] staging: atomisp: Fix fallthrough keyword warning

On Mon, Aug 31, 2020 at 04:30:12PM +0300, Cengiz Can wrote:
> commit df561f6688fe ("treewide: Use fallthrough pseudo-keyword") from
> Gustavo A. R. Silva replaced and standardized /* fallthrough */ comments
> with 'fallthrough' pseudo-keyword.
> 
> However, in one of the switch-case statements, Coverity Static Analyzer
> throws a warning that 'fallthrough' is unreachable due to the adjacent
> 'return false' statement.
> 
> Since 'fallthrough' is actually an empty "do {} while(0)" this might be
> due to compiler optimizations. But that needs further investigation.
> 
> In order to fix the unreachable code warning, make adjacent 'return
> false' a part of the previous if statement's else clause.
> 
> Reported-by: Coverity Static Analyzer CID 1466511
> Signed-off-by: Cengiz Can <cengiz@...nel.wtf>
> ---
>  drivers/staging/media/atomisp/pci/atomisp_compat_css20.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c b/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c
> index 1b2b2c68025b..aaa2d0e0851b 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp_compat_css20.c
> @@ -709,8 +709,8 @@ static bool is_pipe_valid_to_current_run_mode(struct atomisp_sub_device *asd,
>  		if (pipe_id == IA_CSS_PIPE_ID_CAPTURE ||
>  		    pipe_id == IA_CSS_PIPE_ID_PREVIEW)
>  			return true;
> -
> -		return false;
> +		else
> +			return false;
>  		fallthrough;

Heh...  Still unreachable, but now it has a checkpatch.pl warning as
well.  Just get rid of the bogus fallthrough annotation.

>  	case ATOMISP_RUN_MODE_VIDEO:
>  		if (!asd->continuous_mode->val) {

regards,
dan carpenter