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Subject: Re: linux-next: build warning after merge of the kspp-gustavo tree
To:     Stephen Rothwell <sfr@canb.auug.org.au>
Cc:     Kees Cook <keescook@chromium.org>,
        Jonathan Marek <jonathan@marek.ca>,
        Rob Clark <robdclark@chromium.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>
References: <20210713102230.728b4899@canb.auug.org.au>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Message-ID: <26f2ec3c-35ae-4361-62a4-ad0a84fc2399@embeddedor.com>
Date:   Mon, 12 Jul 2021 20:10:40 -0500
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Hi Stephen,

On 7/12/21 19:22, Stephen Rothwell wrote:
> Hi all,
> 
> After merging the kspp-gustavo tree, today's linux-next build (arm
> multi_v7_defconfig) produced this warning:
> 
> /home/sfr/next/next/drivers/gpu/drm/msm/msm_gem.c: In function 'msm_gem_new_impl':
> /home/sfr/next/next/drivers/gpu/drm/msm/msm_gem.c:1170:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>  1170 |   if (priv->has_cached_coherent)
>       |      ^
> /home/sfr/next/next/drivers/gpu/drm/msm/msm_gem.c:1173:2: note: here
>  1173 |  default:
>       |  ^~~~~~~
> 
> Introduced by commit
> 
>   d12e339044a0 ("drm/msm: add MSM_BO_CACHED_COHERENT")
> 
> Presumably exposed by commit
> 
>   73ffc61f4a8b ("Makefile: Enable -Wimplicit-fallthrough for Clang")
> 
> though I am not sure why since I am building with gcc.  The first
> commit above introduces a new use of /* fallthrough */

We have previously adopted the new pseudo-keyword macro fallthrough; So,
we want to avoid having more /* fallthrough */ comments being introduced.
This is also being enforced by commit

	73ffc61f4a8b ("Makefile: Enable -Wimplicit-fallthrough for Clang")

for both GCC and Clang.

So, the fix for this issue is merely to replace the /* fallthrough */ comment
with fallthrough;

Thanks
--
Gustavo