[PATCH glibc 3/3] rseq registration tests (v10)

[Florian Weimer]

* Mathieu Desnoyers:

>>>>> +  retpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0));
>>>>> +  if (retpid != pid)
>>>>> +    {
>>>>> +      FAIL_EXIT1 ("waitpid returned %ld, expected %ld",
>>>>> +                  (long int) retpid, (long int) pid);
>>>>> +    }
>>>> 
>>>> Hmm.  Is the TEMP_FAILURE_RETRY really needed?  Our xwaitpid does not
>>>> have this.
>>>
>>> Then how does it deal with a signal interrupting the system call performing
>>> the waitpid (EINTR) ? I do not see WNOHANG being used.
>> 
>> It obscures spurious signals.  In most test cases, if an unexpected
>> signal is delivered, something is quite wrong indeed.  This is why we
>> don't generally hide EINTR errors.
>
> So it means you may have trouble using tools like strace and gdb on those
> tests ? AFAIU those are heavy users of SIGSTOP and SIGCONT. Similarly for
> profilers, those usually rely on a timer-driven signal.

I have never seen any problems with strace due to this.  ptrace has
become a bit more transparent to the tracee since the early days, I
think.

I haven't seen problems under GDB, either, but then tests that fork can
be rather annoying to debug anyway.

Thanks,
Florian