linux-kernel - Re: [PATCH v3] mm:kasan: fix sparse warnings: Should it be static?

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Message-ID: <CA+fCnZd2yG9-bC=3nvDHLvkvz86x-4p0ewBoi4V5T40+BhQJWQ@mail.gmail.com>
Date: Sun, 13 Oct 2024 00:49:33 +0200
From: Andrey Konovalov <andreyknvl@...il.com>
To: Nihar Chaithanya <niharchaithanya@...il.com>
Cc: ryabinin.a.a@...il.com, kasan-dev@...glegroups.com, 
	linux-kernel@...r.kernel.org, skhan@...uxfoundation.org, 
	kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v3] mm:kasan: fix sparse warnings: Should it be static?

On Fri, Oct 11, 2024 at 1:46 PM Nihar Chaithanya
<niharchaithanya@...il.com> wrote:
>
> Yes, when making the global variables kasan_ptr_result and
> kasan_int_result as static volatile, the warnings are removed and
> the variable and assignments are retained, but when just static is
> used I understand that it might be optimized.

For future reference: please write commit messages in a way that is
readable standalone. I.e. without obscured references to the
discussions on the previous versions of the patch. It's fine to give
such references in itself, but you need to give enough context in the
commit message to make it understandable without looking up those
discussions.

>
> Add a fix making the global varaibles - static volatile, removing the
> warnings:
> mm/kasan/kasan_test.c:36:6: warning: symbol 'kasan_ptr_result' was not declared. Should it be static?
> mm/kasan/kasan_test.c:37:5: warning: symbol 'kasan_int_result' was not declared. Should it be static?
>
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202312261010.o0lRiI9b-lkp@intel.com/
> Signed-off-by: Nihar Chaithanya <niharchaithanya@...il.com>
> ---
> v1 -> v2: Used the aproach of making global variables static to resolve the
> warnings instead of local declarations.
>
> v2 -> v3: Making the global variables static volatile to resolve the
> warnings.
>
> Link to v1: https://lore.kernel.org/all/20241011033604.266084-1-niharchaithanya@gmail.com/
> Link to v2: https://lore.kernel.org/all/20241011095259.17345-1-niharchaithanya@gmail.com/
>
>  mm/kasan/kasan_test_c.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c
> index a181e4780d9d..7884b46a1e71 100644
> --- a/mm/kasan/kasan_test_c.c
> +++ b/mm/kasan/kasan_test_c.c
> @@ -45,8 +45,8 @@ static struct {
>   * Some tests use these global variables to store return values from function
>   * calls that could otherwise be eliminated by the compiler as dead code.
>   */
> -void *kasan_ptr_result;
> -int kasan_int_result;
> +static volatile void *kasan_ptr_result;
> +static volatile int kasan_int_result;
>
>  /* Probe for console output: obtains test_status lines of interest. */
>  static void probe_console(void *ignore, const char *buf, size_t len)
> --
> 2.34.1
>

Reviewed-by: Andrey Konovalov <andreyknvl@...il.com>

Thank you for fixing this!