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

[Mathieu Desnoyers]

----- On May 27, 2020, at 11:12 AM, Florian Weimer fweimer@redhat.com wrote:

> * 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.

OK so I'll use the xwaitpid wrapper and let this be someone else's problem.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com