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Date:   Tue, 11 Feb 2020 14:12:08 +0100
From:   Vasily Gorbik <gor@linux.ibm.com>
To:     Nathan Chancellor <natechancellor@gmail.com>
Cc:     Heiko Carstens <heiko.carstens@de.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com
Subject: Re: [PATCH] s390/time: Fix clk type in get_tod_clock
References: <20200208140858.47970-1-natechancellor@gmail.com>
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On Sat, Feb 08, 2020 at 07:08:59AM -0700, Nathan Chancellor wrote:
> Clang warns:
> 
> In file included from ../arch/s390/boot/startup.c:3:
> In file included from ../include/linux/elf.h:5:
> In file included from ../arch/s390/include/asm/elf.h:132:
> In file included from ../include/linux/compat.h:10:
> In file included from ../include/linux/time.h:74:
> In file included from ../include/linux/time32.h:13:
> In file included from ../include/linux/timex.h:65:
> ../arch/s390/include/asm/timex.h:160:20: warning: passing 'unsigned char
> [16]' to parameter of type 'char *' converts between pointers to integer
> types with different sign [-Wpointer-sign]
>         get_tod_clock_ext(clk);
>                           ^~~
> ../arch/s390/include/asm/timex.h:149:44: note: passing argument to
> parameter 'clk' here
> static inline void get_tod_clock_ext(char *clk)
>                                            ^
> 
> Change clk's type to just be char so that it matches what happens in
> get_tod_clock_ext.
> 
> Fixes: 57b28f66316d ("[S390] s390_hypfs: Add new attributes")
> Link: https://github.com/ClangBuiltLinux/linux/issues/861
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> 
> Alternatively, changing the clk type in get_tod_clock_ext to unsigned
> which is what it was in the early 2000s.
> 
>  arch/s390/include/asm/timex.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
> index 670f14a228e5..6bf3a45ccfec 100644
> --- a/arch/s390/include/asm/timex.h
> +++ b/arch/s390/include/asm/timex.h
> @@ -155,7 +155,7 @@ static inline void get_tod_clock_ext(char *clk)
>  
>  static inline unsigned long long get_tod_clock(void)
>  {
> -	unsigned char clk[STORE_CLOCK_EXT_SIZE];
> +	char clk[STORE_CLOCK_EXT_SIZE];
>  
>  	get_tod_clock_ext(clk);
>  	return *((unsigned long long *)&clk[1]);
> -- 
> 2.25.0
> 
Applied, thanks.
I wonder though if Fixes: tag is really required for such changes. It
triggers stable backports (for all stable branches since v2.6.35) and
hence a lot of noise.