Re: [PATCH] selftests: kselftest: fix wrong test number in ksft_exit_skip

[Sarthak Sharma <sarthak.sharma@arm.com>]

Hi Shuah!

On 4/27/26 11:14 PM, Shuah Khan wrote:
> On 4/27/26 05:24, Sarthak Sharma wrote:
>> ksft_exit_skip() increments ksft_xskip before printing the KTAP
>> result. As a result, ksft_test_num() already includes the skipped
>> test.
>>
>> Adding 1 to ksft_test_num() increments the printed test number
>> again, producing an incorrect test number and wrong KTAP output.
>>
>> Drop the extra increment and print ksft_test_num() directly.
> 
> I applied this patch to linux-kselftest fixes branch.
> 
> I ran a few tests and couldn't really see the problem this patch
> fixes with and without the patch.
> 
> Can you send me before and after for mm or timers test runs?

Sure, this will affect the output whenever a ksft_exit_skip() is called
after a ksft plan has been printed.

Let us look at acct_syscall test. When I run the test without root, I
get the following output before applying the patch:

TAP version 13
1..1
ok 2 # SKIP This test needs root to run!
# 1 skipped test(s) detected. Consider enabling relevant config options
to improve coverage.
# Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0

where we should have observed ok 1 instead of ok 2.

When I run the test without root, after applying the patch, I get the
corrected output:

TAP version 13
1..1
ok 1 # SKIP This test needs root to run!
# 1 skipped test(s) detected. Consider enabling relevant config options
to improve coverage.
# Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0

Since a lot of selftests are being formatted to give KTAP output right
now, this patch is expected to fix a larger number of tests once that
gets merged.

> 
>>
>> Fixes: b85d387c9b09 ("kselftest: fix TAP output for skipped tests")
>> Signed-off-by: Sarthak Sharma <sarthak.sharma@arm.com>
>> ---
>>   tools/testing/selftests/kselftest.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/
>> selftests/kselftest.h
>> index afbcf8412ae5..827b47cf4df8 100644
>> --- a/tools/testing/selftests/kselftest.h
>> +++ b/tools/testing/selftests/kselftest.h
>> @@ -449,7 +449,7 @@ static inline __noreturn __printf(1, 2) void
>> ksft_exit_skip(const char *msg, ...
>>        */
>>       if (ksft_plan || ksft_test_num()) {
>>           ksft_cnt.ksft_xskip++;
>> -        printf("ok %u # SKIP ", 1 + ksft_test_num());
>> +        printf("ok %u # SKIP ", ksft_test_num());
>>       } else {
>>           printf("1..0 # SKIP ");
>>       }
> 
> thanks,
> -- Shuah