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List:       linux-omap
Subject:    Re: [PATCH] ARM: OMAP: dma: Mark expected switch fall-throughs
From:       Kees Cook <keescook () chromium ! org>
Date:       2019-07-29 16:34:40
Message-ID: 201907290934.B2053972E3 () keescook
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On Sun, Jul 28, 2019 at 06:22:40PM -0500, Gustavo A. R. Silva wrote:
> Mark switch cases where we are expecting to fall through.
> 
> This patch fixes the following warnings:
> 
> arch/arm/plat-omap/dma.c: In function 'omap_set_dma_src_burst_mode':
> arch/arm/plat-omap/dma.c:384:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (dma_omap2plus()) {
>       ^
> arch/arm/plat-omap/dma.c:393:2: note: here
>   case OMAP_DMA_DATA_BURST_16:
>   ^~~~
> arch/arm/plat-omap/dma.c:394:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (dma_omap2plus()) {
>       ^
> arch/arm/plat-omap/dma.c:402:2: note: here
>   default:
>   ^~~~~~~
> arch/arm/plat-omap/dma.c: In function 'omap_set_dma_dest_burst_mode':
> arch/arm/plat-omap/dma.c:473:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>    if (dma_omap2plus()) {
>       ^
> arch/arm/plat-omap/dma.c:481:2: note: here
>   default:
>   ^~~~~~~
> 
> Notice that, in this particular case, the code comment is
> modified in accordance with what GCC is expecting to find.
> 
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  arch/arm/plat-omap/dma.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
> index 79f43acf9acb..08c99413d02c 100644
> --- a/arch/arm/plat-omap/dma.c
> +++ b/arch/arm/plat-omap/dma.c
> @@ -388,17 +388,15 @@ void omap_set_dma_src_burst_mode(int lch, enum omap_dma_burst_mode burst_mode)
>  		/*
>  		 * not supported by current hardware on OMAP1
>  		 * w |= (0x03 << 7);
> -		 * fall through
>  		 */
> +		/* fall through */
>  	case OMAP_DMA_DATA_BURST_16:
>  		if (dma_omap2plus()) {
>  			burst = 0x3;
>  			break;
>  		}
> -		/*
> -		 * OMAP1 don't support burst 16
> -		 * fall through
> -		 */
> +		/* OMAP1 don't support burst 16 */
> +		/* fall through */
>  	default:
>  		BUG();
>  	}
> @@ -474,10 +472,8 @@ void omap_set_dma_dest_burst_mode(int lch, enum omap_dma_burst_mode burst_mode)
>  			burst = 0x3;
>  			break;
>  		}
> -		/*
> -		 * OMAP1 don't support burst 16
> -		 * fall through
> -		 */
> +		/* OMAP1 don't support burst 16 */
> +		/* fall through */
>  	default:
>  		printk(KERN_ERR "Invalid DMA burst mode\n");
>  		BUG();
> -- 
> 2.22.0
> 

-- 
Kees Cook
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