linux-kernel - Re: [PATCH] arm64: hw_breakpoint: mark expected switch fall-through

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Message-ID: <763dd408-7ac0-436c-d952-1decff5c696e@embeddedor.com>
Date:   Sun, 28 Jul 2019 18:34:02 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Matteo Croce <mcroce@...hat.com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: hw_breakpoint: mark expected switch fall-through

Hi Matteo,

I sent a patch for this some minutes ago:

https://lore.kernel.org/patchwork/patch/1106585/

It seems there are more warnings in that file than the ones you are
addressing.

Thanks
--
Gustavo

On 7/28/19 6:27 PM, Matteo Croce wrote:
> Mark switch cases where we are expecting to fall through,
> fixes the following warning:
> 
>   CC      arch/arm64/kernel/hw_breakpoint.o
> arch/arm64/kernel/hw_breakpoint.c: In function ‘hw_breakpoint_arch_parse’:
> arch/arm64/kernel/hw_breakpoint.c:540:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>     if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
>        ^
> arch/arm64/kernel/hw_breakpoint.c:542:3: note: here
>    case 2:
>    ^~~~
> arch/arm64/kernel/hw_breakpoint.c:544:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
>     if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
>        ^
> arch/arm64/kernel/hw_breakpoint.c:546:3: note: here
>    default:
>    ^~~~~~~
> 
> Signed-off-by: Matteo Croce <mcroce@...hat.com>
> ---
>  arch/arm64/kernel/hw_breakpoint.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
> index dceb84520948..7d846985b133 100644
> --- a/arch/arm64/kernel/hw_breakpoint.c
> +++ b/arch/arm64/kernel/hw_breakpoint.c
> @@ -539,10 +539,12 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
>  			/* Allow single byte watchpoint. */
>  			if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
>  				break;
> +			/* fallthrough */
>  		case 2:
>  			/* Allow halfword watchpoints and breakpoints. */
>  			if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
>  				break;
> +			/* fallthrough */
>  		default:
>  			return -EINVAL;
>  		}
>