linux-kernel - Re: [PATCH] mips: asm: fix warning when disabling MIPS_FP

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Message-ID: <ZyIVeSZpqG1co4z6@alpha.franken.de>
Date: Wed, 30 Oct 2024 12:16:09 +0100
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Jonas Gorski <jonas.gorski@...il.com>
Cc: Paul Burton <paulburton@...nel.org>, linux-mips@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mips: asm: fix warning when disabling MIPS_FP_SUPPORT

On Sat, Oct 12, 2024 at 12:12:14PM +0200, Jonas Gorski wrote:
> When MIPS_FP_SUPPORT is disabled, __sanitize_fcr31() is defined as
> nothing, which triggers a gcc warning:
> 
>     In file included from kernel/sched/core.c:79:
>     kernel/sched/core.c: In function 'context_switch':
>     ./arch/mips/include/asm/switch_to.h:114:39: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
>       114 |                 __sanitize_fcr31(next);                                 \
>           |                                       ^
>     kernel/sched/core.c:5316:9: note: in expansion of macro 'switch_to'
>      5316 |         switch_to(prev, next, prev);
>           |         ^~~~~~~~~
> 
> Fix this by providing an empty body for __sanitize_fcr31() like one is
> defined for __mips_mt_fpaff_switch_to().
> 
> Fixes: 36a498035bd2 ("MIPS: Avoid FCSR sanitization when CONFIG_MIPS_FP_SUPPORT=n")
> Signed-off-by: Jonas Gorski <jonas.gorski@...il.com>
> ---
>  arch/mips/include/asm/switch_to.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/include/asm/switch_to.h b/arch/mips/include/asm/switch_to.h
> index a4374b4cb88fd830f8b83caab52d6e3c133fd0c4..d6ccd53440213315ec75a54caf683c32c69dcdbe 100644
> --- a/arch/mips/include/asm/switch_to.h
> +++ b/arch/mips/include/asm/switch_to.h
> @@ -97,7 +97,7 @@ do {									\
>  	}								\
>  } while (0)
>  #else
> -# define __sanitize_fcr31(next)
> +# define __sanitize_fcr31(next) do { (void) (next); } while (0)
>  #endif
>  
>  /*
> 
> ---
> base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc
> change-id: 20241012-mips-fcr31-warning-d4eebcfc91c5

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]