[LTP] rt_sigtimedwait01 failed in armv7l

[Cyril Hrubis]

Hi!
> Hi, These is a fail about rt_sigtimedwait01(armv7l GNU/Linux and linux 3.10):
> root@arma9el:/tmp# ./rt_sigtimedwait01
> rt_sigtimedwait01    0  TINFO  :  0x9fd0, 10
> rt_sigtimedwait01    1  TPASS  :  Test passed
> rt_sigtimedwait01    0  TINFO  :  0x9fd0, 10
> rt_sigtimedwait01    2  TPASS  :  Test passed
> ...
> rt_sigtimedwait01    0  TINFO  :  0x9fd0, 12
> rt_sigtimedwait01   11  TPASS  :  Test passed
> rt_sigtimedwait01    0  TINFO  :  0x9fd0, 15
> rt_sigtimedwait01   12  TPASS  :  Test passed
> rt_sigtimedwait01   12  TPASS  :  sigwaitinfo restored the original mask
> rt_sigtimedwait01    0  TINFO  :  0x9fd0, -1
> 
> rt_sigtimedwait01   13  TFAIL  :  /home/cuibixuan/ltp/testcases/kernel/syscalls/rt_sigtimedwait/../sigwaitinfo/sigwaitinfo01.c:56:
> test_masked_matching_rt (/home/cuibixuan/ltp/testcases/kernel/syscalls/rt_sigtimedwait/../sigwaitinfo/sigwaitinfo01.c: 274): Unexpected return value; expected 35, got 36
> rt_sigtimedwait01   13  TFAIL  :  /home/cuibixuan/ltp/testcases/kernel/syscalls/rt_sigtimedwait/../sigwaitinfo/sigwaitinfo01.c:56:
> test_masked_matching_rt (/home/cuibixuan/ltp/testcases/kernel/syscalls/rt_sigtimedwait/../sigwaitinfo/sigwaitinfo01.c: 282): Unexpected return value; expected 36, got 35
> rt_sigtimedwait01   13  TPASS  :  sigwaitinfo restored the original mask
> 
> 
> I add 'sleep(1)' into test_masked_matching_rt() of ltp/testcases/kernel/syscalls/sigwaitinfo/sigwaitinfo01.c:268
> 
> void test_masked_matching_rt(swi_func sigwaitinfo, int signo)
> ...
> /* Run a child that will wake us up */
>         child[0] = create_sig_proc(0, signo, 1);
> +       sleep(1);
>         child[1] = create_sig_proc(0, signo + 1, 1);
> 
> Then the case pass:
> rt_sigtimedwait01   13  TPASS  :  Test passed
> rt_sigtimedwait01   13  TPASS  :  Test passed
> rt_sigtimedwait01   13  TPASS  :  sigwaitinfo restored the original mask
> 
> Or run it by 'chrt 10 ./rt_sigtimedwait01' then pass.
> 
> Why? Can someone give me a hand.

I guess that the problem here is that the order in which the test
children and parent are executed is undefined.

The signals should be delivered starting from lowest numbered but that
applies only when both signals are pending at the point we call
sigwaitinfo(). If, by a chance, the first child haven't had chance to
finish until we get to the sigwaitinfo() call we will get the signo+1
signal first, since that is the only one pending at that point.

So the fix here would be making sure that both children are finished
before we call the sigwaitinfo(). Quite possibly doing waitpid() for
both of them will suffice.

-- 
Cyril Hrubis
chrubis@suse.cz