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From: SeongJae Park <sj@kernel.org>
To: Rong Tao <rtoax@foxmail.com>
Cc: sj@kernel.org,
	damon@lists.linux.dev,
	linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	linux-mm@kvack.org,
	rongtao@cestc.cn,
	shuah@kernel.org,
	yuanchu@google.com
Subject: Re: Re: [PATCH] selftests/damon: Fix unnecessary compilation warnings
Date: Sat, 12 Nov 2022 18:30:50 +0000
Message-Id: <20221112183050.85200-1-sj@kernel.org>
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Hi Rong,

On Sat, 12 Nov 2022 13:01:04 +0800 Rong Tao <rtoax@foxmail.com> wrote:

> Hi, Park, I just search on GCC source code, found GCC support
> "-Wstringop-overread" at least gcc-11.1.0, commit d14c547abd48("Add
> -Wstringop-overread for reading past the end by string functions.").
> 
> AND found a testsuite gcc/gcc/testsuite/gcc.dg/pragma-diag-10.c
> 
>  10 #pragma GCC diagnostic push
>  11 #pragma GCC diagnostic ignored "-Wstringop-overflow"
>  12 #pragma GCC diagnostic ignored "-Wstringop-overread"
>  13   if (c != 0)
>  14     return __builtin_memchr (s, c, (unsigned long)-1);
>  15 #pragma GCC diagnostic pop
> 
> it's totally same as this PATCH.
> 
> I think the motivation for this patch is to eliminate the compilation
> warning, maybe one day we will compile the kernel with "-Werror -Wall",
> at which point this compilation warning will turn into a compilation
> error, and in case we already know it, we should fix this error in
> advance.
> 
> For old gcc, we can add this?
> 
>  #pragma GCC diagnostic push
> +#if __GNUC__ >= 11 && __GNUC_MINOR__ >= 1
>  /* Ignore read(2) overflow and write(2) overread compile warnings */
>  #pragma GCC diagnostic ignored "-Wstringop-overread"
>  #pragma GCC diagnostic ignored "-Wstringop-overflow"
> +#endif
> 
> What do you think?

I think it looks great!  Looking forward to your v3 patch!


Thanks,
SJ

> 
> Good day!
> Rong Tao