Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
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>
In-Reply-To: <tencent_5695C257F3D13F4417034BA1FBAC95CB3B07@qq.com>
References: 
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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