linux-kernel - Re: [PATCH 6/9] ARM: uaccess: avoid warning for NOMMU in access

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Message-ID: <alpine.LFD.2.20.1602181115040.13632@knanqh.ubzr>
Date:	Thu, 18 Feb 2016 11:15:32 -0500 (EST)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Arnd Bergmann <arnd@...db.de>
cc:	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Jon Medhurst <tixy@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Will Deacon <will.deacon@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/9] ARM: uaccess: avoid warning for NOMMU in access_ok

On Thu, 18 Feb 2016, Arnd Bergmann wrote:

> When CONFIG_MMU is disabled, the access_ok() and __range_ok()
> macros always return success, and there is a cast to void
> to ensure the compiler does not warn about an unused address
> variable. However, at least one driver has a variable for
> the size argument as well and does warn about that one:
> 
> drivers/vhost/vhost.c: In function 'vq_access_ok':
> drivers/vhost/vhost.c:633:9: warning: unused variable 's' [-Wunused-variable]
> 
> This changes the macro to also ignore the size argument
> explicitly to shut up that warning.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Acked-by: Nicolas Pitre <nico@...aro.org>

> ---
>  arch/arm/include/asm/uaccess.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
> index 35c9db857ebe..9c74c84a10d2 100644
> --- a/arch/arm/include/asm/uaccess.h
> +++ b/arch/arm/include/asm/uaccess.h
> @@ -290,7 +290,7 @@ extern int __put_user_8(void *, unsigned long long);
>  
>  #define segment_eq(a, b)		(1)
>  #define __addr_ok(addr)		((void)(addr), 1)
> -#define __range_ok(addr, size)	((void)(addr), 0)
> +#define __range_ok(addr, size)	((void)(addr), (void)(size), 0)
>  #define get_fs()		(KERNEL_DS)
>  
>  static inline void set_fs(mm_segment_t fs)
> -- 
> 2.7.0
> 
>