linux-kernel - Re: [PATCH 1/7] selftests: vDSO: chacha: Correctly skip test if necessary

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Message-ID: <c01d8c7e-bac7-4d4d-872d-14f0ac0c6ec2@collabora.com>
Date: Fri, 2 May 2025 18:42:55 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>,
 Andy Lutomirski <luto@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 Vincenzo Frascino <vincenzo.frascino@....com>, Shuah Khan
 <shuah@...nel.org>, "Jason A. Donenfeld" <Jason@...c4.com>
Cc: usama.anjum@...labora.com, Shuah Khan <skhan@...uxfoundation.org>,
 linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 1/7] selftests: vDSO: chacha: Correctly skip test if
 necessary

On 5/2/25 5:40 PM, Thomas Weißschuh wrote:
> According to kselftest.h ksft_exit_skip() is not meant to be called when
> a plan has already been printed.
Agreed

> 
> Use the recommended function ksft_test_result_skip().
> 
> This fixes a bug, where the TAP output would be invalid when skipping:
> 
> 	TAP version 13
> 	1..1
> 	ok 2 # SKIP Not implemented on architecture
> 
> The SKIP line should start with "ok 1" as the plan only contains one test.
> 
> Fixes: 3b5992eaf730 ("selftests: vDSO: unconditionally build chacha test")
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@...labora.com>

> 
> ---
> I'm not sure if this is not a general bug in ksft_exit_skip().
> First ksft_xskip is incremented then read back through ksft_test_num() and
> then that result is incremented again.
> 
> In any case, using the correct function is better.
> ---
>  tools/testing/selftests/vDSO/vdso_test_chacha.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/vDSO/vdso_test_chacha.c b/tools/testing/selftests/vDSO/vdso_test_chacha.c
> index 8757f738b0b1a76a48c83c5e5df79925a30c1bc7..0aad682b12c8836efabb49a65a47cf87466891a3 100644
> --- a/tools/testing/selftests/vDSO/vdso_test_chacha.c
> +++ b/tools/testing/selftests/vDSO/vdso_test_chacha.c
> @@ -76,7 +76,8 @@ static void reference_chacha20_blocks(uint8_t *dst_bytes, const uint32_t *key, u
>  
>  void __weak __arch_chacha20_blocks_nostack(uint8_t *dst_bytes, const uint32_t *key, uint32_t *counter, size_t nblocks)
>  {
> -	ksft_exit_skip("Not implemented on architecture\n");
> +	ksft_test_result_skip("Not implemented on architecture\n");
> +	ksft_finished();
>  }
>  
>  int main(int argc, char *argv[])
> 


-- 
Regards,
Usama