linux-kernel - Re: [PATCH v3 01/19] powerpc/powermac: Mark variable x as unused

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Date:   Tue, 24 Apr 2018 16:12:35 +0200
From:   Christophe LEROY <christophe.leroy@....fr>
To:     Mathieu Malaterre <malat@...ian.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 01/19] powerpc/powermac: Mark variable x as unused



Le 04/04/2018 à 22:07, Mathieu Malaterre a écrit :
> Since the value of x is never intended to be read, declare it with gcc
> attribute as unused. Fix warning treated as error with W=1:
> 
>    arch/powerpc/platforms/powermac/bootx_init.c:471:21: error: variable ‘x’ set but not used [-Werror=unused-but-set-variable]
> 
> Suggested-by: Christophe Leroy <christophe.leroy@....fr>
> Signed-off-by: Mathieu Malaterre <malat@...ian.org>
> ---
> v3: style: add missing empty line after declaration
> v2: move x variable within its local scope
> 
>   arch/powerpc/platforms/powermac/bootx_init.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/platforms/powermac/bootx_init.c b/arch/powerpc/platforms/powermac/bootx_init.c
> index c3c9bbb3573a..ba0964c17620 100644
> --- a/arch/powerpc/platforms/powermac/bootx_init.c
> +++ b/arch/powerpc/platforms/powermac/bootx_init.c
> @@ -468,7 +468,7 @@ void __init bootx_init(unsigned long r3, unsigned long r4)
>   	boot_infos_t *bi = (boot_infos_t *) r4;
>   	unsigned long hdr;
>   	unsigned long space;
> -	unsigned long ptr, x;
> +	unsigned long ptr;
>   	char *model;
>   	unsigned long offset = reloc_offset();
>   
> @@ -562,6 +562,8 @@ void __init bootx_init(unsigned long r3, unsigned long r4)
>   	 * MMU switched OFF, so this should not be useful anymore.
>   	 */
>   	if (bi->version < 4) {
> +		unsigned long x __maybe_unused;
> +

That's detail, but shouldn't it be marked __always_unused instead ?

Christophe

>   		bootx_printf("Touching pages...\n");
>   
>   		/*
>