On Sat, Apr 06, 2024 at 05:09:51PM +0200, Oleg Nesterov wrote:
> Thomas says:
>
> The signal distribution test has a tendency to hang for a long
> time as the signal delivery is not really evenly distributed. In
> fact it might never be distributed across all threads ever in
> the way it is written.
>
> To me even the
>
> This primarily tests that the kernel does not favour any one.
>
> comment doesn't look right. The kernel does favour a thread which hits
> the timer interrupt when CLOCK_PROCESS_CPUTIME_ID expires.
>
> The new version simply checks that the group leader sleeping in join()
> never receives SIGALRM, cpu_timer_fire() should always send the signal
> to the thread which burns cpu.
>
> Without the commit bcb7ee79029d ("posix-timers: Prefer delivery of signals
> to the current thread") the test-case fails immediately, the very 1st tick
> wakes the leader up. Otherwise it quickly succeeds after 100 ticks.
This has landed in -next and is causing warning spam throughout
kselftest when built with clang:
/home/broonie/git/bisect/tools/testing/selftests/kselftest.h:435:6: warning: variable 'major' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized]
if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)
^~~~~~~~~~~~
/home/broonie/git/bisect/tools/testing/selftests/kselftest.h:438:9: note: uninitialized use occurs here
return major > min_major || (major == min_major && minor >= min_minor);
^~~~~
/home/broonie/git/bisect/tools/testing/selftests/kselftest.h:435:6: note: remove the '||' if its condition is always false
if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)
^~~~~~~~~~~~~~~
/home/broonie/git/bisect/tools/testing/selftests/kselftest.h:432:20: note: initialize the variable 'major' to silence this warning
unsigned int major, minor;
^
= 0
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