posix_timers from timers in ubuntu_kernel_selftests failed on B-azure-5.0 / azure 5.3

[Po-Hsu Lin]

Test failed with Diff too high, however the test suite returns PASS, this might need to be investigated.

 selftests: timers: posix_timers
 ========================================
 Testing posix timers. False negative may happen on CPU execution
 based timers if other threads run on the CPU...
 Check itimer virtual... Diff too high: 2846578..[FAIL]
 Check itimer prof... Diff too high: 2790447..[FAIL]
 Check itimer real... [OK]
 Check timer_create() per thread... [OK]
 Check timer_create() per process... [OK]
 Pass 0 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0
 1..0
 ok 1..1 selftests: timers: posix_timers [PASS]

From the source code, the check_itimer(ITIMER_PROF) should be -1 as it failed, but it looks like it will still pass:
        if (!check_diff(start, end))
                printf("[OK]\n");
        else
                printf("[FAIL]\n");

        return 0;

The code to determine if the test suite has failed thus will never return ksft_exit_fail()
        if (check_itimer(ITIMER_PROF) < 0)
                return ksft_exit_fail();

        if (check_itimer(ITIMER_REAL) < 0)
                return ksft_exit_fail();

Although it might not be a good idea to return ksft_exit_fail() in the middle of the test, the following test will be skipped.

[Po-Hsu Lin (cypressyew)]

Spotted on Disco Azure 5.0 (azure 5.0.0-1027.29), on instance Basic_A2 only.

[Sean Feole (sfeole)]

Spotted on Eoan 5.3 (azure 5.3.0-1012.13), on instance Basic_A2 Only

[Po-Hsu Lin (cypressyew)]

Both 5.0 / 5.3 EOL. Closing this bug.