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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: [PATCH v3] selftests/damon: Fix unnecessary compilation warnings
Date:   Sun, 13 Nov 2022 19:49:07 +0000
Message-Id: <20221113194908.18554-1-sj@kernel.org>
In-Reply-To: <tencent_51C4ACA8CB3895C2D7F35178440283602107@qq.com>
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On Sun, 13 Nov 2022 08:38:45 +0800 Rong Tao <rtoax@foxmail.com> wrote:

> From: Rong Tao <rongtao@cestc.cn>
> 
> When testing overflow and overread, there is no need to keep unnecessary
> compilation warnings, we should simply ignore them.
> 
> 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, we
> should fix this error in advance.
> 
> How to reproduce the problem (with gcc-11.3.1):
> 
>     $ make -C tools/testing/selftests/
>     ...
>     warning: ‘write’ reading 4294967295 bytes from a region of size 1
>     [-Wstringop-overread]
>     warning: ‘read’ writing 4294967295 bytes into a region of size 25
>     overflows the destination [-Wstringop-overflow=]
> 
> "-Wno-stringop-overread" is supported at least in gcc-11.1.0.
> 
> Link: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=d14c547abd484d3540b692bb8048c4a6efe92c8b
> Signed-off-by: Rong Tao <rongtao@cestc.cn>

Reviewed-by: SeongJae Park <sj@kernel.org>

Thank you for fixing this old problem!


Thanks,
SJ

> ---
>  tools/testing/selftests/damon/huge_count_read_write.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
> index ad7a6b4cf338..a6fe0689f88d 100644
> --- a/tools/testing/selftests/damon/huge_count_read_write.c
> +++ b/tools/testing/selftests/damon/huge_count_read_write.c
> @@ -8,6 +8,13 @@
>  #include <unistd.h>
>  #include <stdio.h>
>  
> +#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
> +
>  void write_read_with_huge_count(char *file)
>  {
>  	int filedesc = open(file, O_RDWR);
> @@ -27,6 +34,8 @@ void write_read_with_huge_count(char *file)
>  	close(filedesc);
>  }
>  
> +#pragma GCC diagnostic pop
> +
>  int main(int argc, char *argv[])
>  {
>  	if (argc != 2) {
> -- 
> 2.31.1
> 
>