Re: [PATCH RFC] selftests/pidfd: Fix duplicate-symbol warnings for SCHED_ CPP symbols

[Shuah Khan]

On 7/14/25 17:01, Paul E. McKenney wrote:
> The pidfd selftests run in userspace and include both userspace and kernel
> header files.  On some distros (for example, CentOS), this results in
> duplicate-symbol warnings in allmodconfig builds, while on other distros
> (for example, Ubuntu) it does not.  (This happens in recent -next trees,
> including next-20250714.)
>
> Therefore, use #undef to get rid of the userspace definitions in favor
> of the kernel definitions.
>
> Other ways of handling this include splitting up the selftest code so
> that the userspace definitions go into one translation unit and the
> kernel definitions into another (which might or might not be feasible)
> or to adjust compiler command-line options to suppress the warnings
> (which might or might not be desirable).
>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Cc: Christian Brauner <brauner@xxxxxxxxxx>
> Cc: Shuah Khan <shuah@xxxxxxxxxx>
> Cc: <linux-kselftest@xxxxxxxxxxxxxxx>
>
> ---
>   pidfd.h |    4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h
> index efd74063126eb..6ff495398e872 100644
> --- a/tools/testing/selftests/pidfd/pidfd.h
> +++ b/tools/testing/selftests/pidfd/pidfd.h
> @@ -16,6 +16,10 @@
>   #include <sys/types.h>
>   #include <sys/wait.h>
>   

Please add comments here about why we are adding this so there
won't be any confusion later.

> +#undef SCHED_NORMAL
> +#undef SCHED_FLAG_KEEP_ALL
> +#undef SCHED_FLAG_UTIL_CLAMP
> +
>   #include "../kselftest.h"
>   #include "../clone3/clone3_selftests.h"
>   

With that change:

Reviewed-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>

I am assuming this will go through Christian's tree. If not I can
take it through mine.

thanks,
-- Shuah