[gst 1.2.2] remove a request pad from videomixer cause SEGFAULT

[Lautaro Woites]

2014/1/23 Sebastian Dröge <sebastian at centricular.com>

> On Mi, 2014-01-22 at 17:51 -0200, Lautaro Woites wrote:
> > Hi again folks,
> >
> > I have this pipe: videotestsrc ! capsfilter ! videomixer ! xvimagesink.
> > Then on PLAYING STATE I do:
> >
> > while (TRUE){
> >     sleep(2);
> >     add_mixer_input(); //adds an input on the videomixer
> >     sleep(2);
> >     remove_mixer_input(); //removes the previously added input to the
> mixer.
> > }
> >
> > The inputs are bins with videotestsrc and a capsfilter. The example runs
> > for a time (sometimes 5 minutes, sometimes 30 min, others 10 seconds) and
> > then produces a segmentation fault on the videomixer (at
> > gst_collect_pads_check_collected:1031).
> >
> > This is what I do to remove the input:
> >      a) I  block the videotestsrc's src pad.
> >      b) I send an EOS event to the capsfilter's sink pad and I wait for
> the
> > event on the bin's src pad ( with an event probe).
> >      c) On the  event probe's callback I drop the EOS and I unlink the
> bin
> > with the mixer.
> >      d) I set the bin to STATE_NULL and I remove it from the pipe.
> >      e) I call release_request_pad on the mixer.
> >      f) I remove the block pad on the videotestsrc.
> > Also I've tried: to send EOS to the videtestsrc - set the bin to
> STATE_NULL
> > and remove it - and finally call release_request_pad on the mixer.
> > The program  crashed in the same line .
> >
> > NOTE:   If I remove the call to gst_release_request_pad the program seems
> > to work OK. But the mixer's will still having unused sink pads :(.
>
> The sequence of actions sounds correct
>
> > I have some question about this:
> >    1) I don't know if I am missing something or if there is a bug.
> >    2) If I'm doing something wrong, What's the correct/safest  protocol
> to
> > remove an input from the mixer?.
> >    3) is it related with this ticket:
> > https://bugzilla.gnome.org/show_bug.cgi?id=701110 ?
>
> It might indeed be this bug, but then it wouldn't happen always. Could
> you attach a testcase to that bug that reproduces the crash? What you're
> doing is supposed to work and definitely should not crash.
>
>
OK I've attached an example to the ticket.

Hope it helps. If you need more info just tell me.


> --
> Sebastian Dröge, Centricular Ltd - http://www.centricular.com
> Expertise, Straight from the Source
>
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