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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Tue, 18 Sep 2018 08:52:00 -0700
Message-ID: <CAKv+Gu8xkeKb1-ce_hNCcXLrdj+qdi2DsXWPUuAiZQY1Rz+rmw@mail.gmail.com>
Subject: Re: [PATCH 2/2] crypto: arm/crc32 - avoid warning when compiling with Clang
To:     Stefan Agner <stefan@agner.ch>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Russell King <linux@armlinux.org.uk>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On 15 September 2018 at 21:38, Stefan Agner <stefan@agner.ch> wrote:
> The table id (second) argument to MODULE_DEVICE_TABLE is often
> referenced otherwise. This is not the case for CPU features. This
> leads to a warning when building the kernel with Clang:
>   arch/arm/crypto/crc32-ce-glue.c:239:33: warning: variable
>     'crc32_cpu_feature' is not needed and will not be emitted
>     [-Wunneeded-internal-declaration]
>   static const struct cpu_feature crc32_cpu_feature[] = {
>                                   ^
>
> Avoid warnings by using __maybe_unused, similar to commit 1f318a8bafcf
> ("modules: mark __inittest/__exittest as __maybe_unused").
>
> Fixes: 2a9faf8b7e43 ("crypto: arm/crc32 - enable module autoloading based on CPU feature bits")
> Signed-off-by: Stefan Agner <stefan@agner.ch>

Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

> ---
>  arch/arm/crypto/crc32-ce-glue.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/crypto/crc32-ce-glue.c b/arch/arm/crypto/crc32-ce-glue.c
> index 96e62ec105d0..cd9e93b46c2d 100644
> --- a/arch/arm/crypto/crc32-ce-glue.c
> +++ b/arch/arm/crypto/crc32-ce-glue.c
> @@ -236,7 +236,7 @@ static void __exit crc32_pmull_mod_exit(void)
>                                   ARRAY_SIZE(crc32_pmull_algs));
>  }
>
> -static const struct cpu_feature crc32_cpu_feature[] = {
> +static const struct cpu_feature __maybe_unused crc32_cpu_feature[] = {
>         { cpu_feature(CRC32) }, { cpu_feature(PMULL) }, { }
>  };
>  MODULE_DEVICE_TABLE(cpu, crc32_cpu_feature);
> --
> 2.19.0
>