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 17:12:30 +0200 [thread overview]
Message-ID: <87blm9h0o1.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <1647263261.34186.1590504195448.JavaMail.zimbra@efficios.com> (Mathieu Desnoyers's message of "Tue, 26 May 2020 10:43:15 -0400 (EDT)")
* 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
next prev parent reply other threads:[~2020-05-27 15:12 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 [this message]
2020-05-27 15:17 ` Mathieu Desnoyers
2020-05-27 15:21 ` Florian Weimer
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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