[LTP] [PATCH 1/2] POSIX: Allow pthread_barrier_destroy() to block

[Cyril Hrubis]

Hi!
> >> -	/* Cleanup (cancel thread in case it is still blocking */
> >> +	printf("Test PASSED\n");
> >
> > What about we fail the test in a case that we do not get either of
> > success or EBUSY? I doubt that there is any harm in making this kind of
> > check here with the watchdog thread in place.
> >
> 
> I suppose it would be misleading if it returned EINVAL, but it would
> only be an error if it returned EINTR because that is specifically
> prohibited by the spec.
> 
> Thinking about it, it is all undefined behaviour, but the test is to see
> if it complies with the recommended behviour. So maybe we should fail
> the test if it does not return EBUSY. If someone doesn't agree with the
> recommended behaviour they can ignore the test.

The open posix testsuite has PTS_UNSUPPORTED status that is used when
optional part of the POSIX standard is not implemented, that makes much
more sense than fail in this case.

> I don't have a strong opinion on whether the test should pass or
> fail. However I would like to have some clear rules to follow for the
> POSIX tests. Like "If it is undefined behaviour then anything except a
> null pointer derefernce or buffer overflow is acceptable". So basically
> any behaviour that isn't obviously a security/integrity concern is OK. Or
> something like "If it is undefined behaviour then we check if it follows
> the recommended behaviour", and make it clear in the test description
> that this test may fail on a compliant implementation.

My intent with these testcases was always to make them first class
citizen on Linux but at the same time keep them working on any other
Unix. The fact that Linux does not implement most of the optional
features makes it a bit more complicated though.

So in this case I would go for passing the test only if the optional
EBUSY error is implemented and return UNSUPPORTED otherwise. I would
still keep the code with watchdog there so that the case that the call
blocks until the barrier is in use blocks is handled gracefully though.

Does that sound reasonable?

And yes I think that keeping the test just to see if we cannot get
SegFault or something in this case is valuable even though POSIX
technically allows such behavior.

-- 
Cyril Hrubis
chrubis@suse.cz