Re: [PATCH v2 1/2] perf record: Propagate exit status of a command line workload

From: Stephane Eranian
Date: Wed Apr 23 2014 - 10:40:32 EST


On Wed, Apr 23, 2014 at 4:38 PM, Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
> Hi Stephane,
>
> 2014-04-23 (ì), 14:11 +0200, Stephane Eranian:
>> On Wed, Apr 23, 2014 at 8:40 AM, Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>> > +out_child:
>> > + if (forks) {
>> > + int exit_status;
>> >
>> > - return 0;
>> > + if (!child_finished)
>> > + kill(rec->evlist->workload.pid, SIGTERM);
>> > +
>> > + wait(&exit_status);
>> > +
>> > + if (err < 0)
>> Not quite this. Although this works with my test case with 'false'.
>> It fails when I tried the opposite test case:
>>
>> $ perf record true && echo yes || echo no
>> [ perf record: Woken up 1 times to write data ]
>> [ perf record: Captured and wrote 0.013 MB perf.data (~589 samples) ]
>> no
>>
>> The return code in this case is 255. I tracked it down to err being last set
>> by poll() which got interrupted by SIGCHLD. So I think the err value must
>> be overridden somehow in this case. Maybe something like:
>>
>> err = poll(evsel_list->pollfd, evsel_list->nr_fds, -1);
>> if (err < 0 && errno == EINTR && forks && done)
>> err = 0;
>
> Hmm.. just checking "err < 0 && errno == EINTR" isn't enough?
>
> And I guess the same problem can be occurred during record__mmap_read()
> as it calls record__write() which eventually calls ion() and it seems
> not to handle the above case.. I'll cook a patch for it too.
>
That's true.
Now, do we care about the return value of poll()?

> Thanks,
> Namhyung
>
>
>
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