linux-kernel - Re: [PATCH v3] bus: arm-cci: remove unnecessary unreachable()

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Date:   Mon, 14 May 2018 01:23:03 -0700
From:   Olof Johansson <olof@...om.net>
To:     Stefan Agner <stefan@...er.ch>
Cc:     arm@...nel.org, arnd@...db.de, linux@...linux.org.uk,
        ard.biesheuvel@...aro.org, robin.murphy@....com,
        nicolas.pitre@...aro.org, marc.zyngier@....com,
        behanw@...verseincode.com, keescook@...omium.org,
        Bernhard.Rosenkranzer@...aro.org, mka@...omium.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] bus: arm-cci: remove unnecessary unreachable()

On Tue, May 08, 2018 at 04:27:26PM +0200, Stefan Agner wrote:
> Mixing asm and C code is not recommended in a naked function by
> gcc and leads to an error when using clang:
>   drivers/bus/arm-cci.c:2107:2: error: non-ASM statement in naked
>   function is not supported
>         unreachable();
>         ^
> 
> While the function is marked __naked it actually properly return
> in asm. There is no need for the unreachable() call.
> 
> GCC 7.2 generates identical object files before and after, other
> than (for obvious reasons) the line numbers generated by
> WANT_WARN_ON_SLOWPATH for all the WARN()s appearing later in the
> file.
> 
> Suggested-by: Russell King <linux@....linux.org.uk>
> Signed-off-by: Stefan Agner <stefan@...er.ch>
> Acked-by: Nicolas Pitre <nico@...aro.org>
> Reviewed-by: Robin Murphy <robin.murphy@....com>
> ---
> Changes in v3:
> - Fix subject and enhance commit message
> Changes in v2:
> - Don't add assembly ASM_UNREACHABLE, just drop unreachable()

Applied to next/drivers for v4.18 merge window now. Thanks!


-Olof