[gstreamer-bugs] [Bug 547835] New: tee release_request_pad while buffer_alloc racyness

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gstreamer (core) | Ver: HEAD CVS
           Summary: tee release_request_pad while buffer_alloc racyness
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gstreamer (core)
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: ole.andre.ravnas at tandberg.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


Releasing a request pad on a tee while a buffer_alloc is in progress on that
same pad is racy.

This goes wrong when gst_tee_find_buffer_alloc is iterating over the pads,
picks a pad that's about to be released in the application's thread, unlocks
tee's object lock to call gst_pad_alloc_buffer() on the pad, and while this is
in progress (gst_pad_buffer_alloc_unchecked()), the application releases the
pad. This unlinks and unparents the pad, and when
gst_pad_buffer_alloc_unchecked() returns back to gst_pad_alloc_buffer_full() it
detects that there's been a caps change because the caps have been cleared as a
consequence of what the release request pad function did, so it tries to do
gst_pad_configure_src() which fails with a g_warning() in
gst_pad_get_caps_unlocked() because the pad no longer has any parent
(obviously).


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