From: Florian Weimer <fweimer@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: libc-alpha <libc-alpha@sourceware.org>,
Joseph Myers <joseph@codesourcery.com>
Subject: Re: [PATCH glibc 3/3] rseq registration tests (v10)
Date: Wed, 27 May 2020 17:21:02 +0200 [thread overview]
Message-ID: <87367lh09t.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <1218946966.36797.1590592662832.JavaMail.zimbra@efficios.com> (Mathieu Desnoyers's message of "Wed, 27 May 2020 11:17:42 -0400 (EDT)")
* 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.
Yes please. Or support_isolate_in_subprocess.
Thanks,
Florian
next prev parent reply other threads:[~2020-05-27 15:21 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 2:14 [PATCH glibc 0/3] Restartable Sequences enablement Mathieu Desnoyers
2020-05-01 2:14 ` [PATCH glibc 1/3] glibc: Perform rseq registration at C startup and thread creation (v19) Mathieu Desnoyers
2020-05-20 11:40 ` Florian Weimer
2020-05-25 14:51 ` Mathieu Desnoyers
2020-05-25 15:20 ` Florian Weimer
2020-05-25 17:36 ` Mathieu Desnoyers
2020-05-26 12:41 ` Florian Weimer
2020-05-26 14:32 ` Mathieu Desnoyers
2020-05-26 14:38 ` Florian Weimer
2020-05-26 14:53 ` Mathieu Desnoyers
2020-05-26 14:57 ` Florian Weimer
2020-05-26 15:22 ` Mathieu Desnoyers
2020-05-01 2:14 ` [PATCH glibc 2/3] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux (v7) Mathieu Desnoyers
2020-05-20 10:14 ` Florian Weimer
2020-05-01 2:14 ` [PATCH glibc 3/3] rseq registration tests (v10) Mathieu Desnoyers
2020-05-20 10:52 ` Florian Weimer
2020-05-25 17:07 ` Mathieu Desnoyers
2020-05-26 12:47 ` Florian Weimer
2020-05-26 14:43 ` Mathieu Desnoyers
2020-05-27 15:05 ` Mathieu Desnoyers
2020-05-27 15:12 ` Florian Weimer
2020-05-27 15:17 ` Mathieu Desnoyers
2020-05-27 15:21 ` Florian Weimer [this message]
2020-05-27 15:30 ` Mathieu Desnoyers
2020-05-20 11:44 ` [PATCH glibc 0/3] Restartable Sequences enablement Florian Weimer
2020-05-25 13:52 ` Mathieu Desnoyers
2020-05-25 14:28 ` Florian Weimer
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