[libcamera-devel] [PATCH v1] test: gstreamer: Fix the destructor of GstreamerTest base class

[Vedant Paranjape]

Hi Kieran,

On Wed, 8 Sep, 2021, 18:57 Kieran Bingham, <kieran.bingham at ideasonboard.com>
wrote:

> On 08/09/2021 14:20, Vedant Paranjape wrote:
> > Hi Kieran,
> >
> > On Wed, Sep 8, 2021 at 6:36 PM Kieran Bingham
> > <kieran.bingham at ideasonboard.com
> > <mailto:kieran.bingham at ideasonboard.com>> wrote:
> >
> >     On 08/09/2021 13:04, Vedant Paranjape wrote:
> >     > The destructor tried to check if pipeline_ is a parent of
> >     libcameraSrc_.
> >     > This was needed to be checked as if it is, cleanup of libcameraSrc_
> >     > would be handled by pipeline itself.
> >     >
> >     > Since, the destructor can be called anytime, even when pipeline_
> >     hasn't
> >     > been created, the use of pipeline_ to check if libcameraSrc_ has an
> >     > ancestor as pipeline_ caused a segmentation fault.
> >
> >     I presume the refcounting is what actually deals with the cleanup
> >     accordingly now?
> >
> >
> > Right !
> >
> >     Will the gst_object_unref(pipeline_); have any effect such as making
> >     libcameraSrc_ invalid? (because you said that the pipeline handler
> would
> >
> >
> > Yes, it will unref the libcameraSrc_, and I think gst_deinit will free
> > it. Pinging @Nicolas Dufresne <mailto:nicolas at ndufresne.ca> for
> clearity.
>
> The question is - have you made sure that the refcounting is correctly
> balanced, such that this final gst_object_unref(libcameraSrc_);  will be
> the one that does the release?
>
> I.e. to make sure it doesn't take the refcount below zero.
>

It can't go below zero, and this is the only place where I do a unref, so
Yes !


> >
> >     It looks reasonable otherwise:
> >
> >     Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com
> >     <mailto:kieran.bingham at ideasonboard.com>>
> >
> >     >
> >     > Fixes: f58768092277 ("test: gstreamer: Fix the destructor of
> >     GstreamerTest base class")
> >     > Signed-off-by: Vedant Paranjape <vedantparanjape160201 at gmail.com
> >     <mailto:vedantparanjape160201 at gmail.com>>
> >     > ---
> >     >  test/gstreamer/gstreamer_test.cpp | 6 ++----
> >     >  1 file changed, 2 insertions(+), 4 deletions(-)
> >     >
> >     > diff --git a/test/gstreamer/gstreamer_test.cpp
> >     b/test/gstreamer/gstreamer_test.cpp
> >     > index dbdcaec0b111..46fa5abaea75 100644
> >     > --- a/test/gstreamer/gstreamer_test.cpp
> >     > +++ b/test/gstreamer/gstreamer_test.cpp
> >     > @@ -69,12 +69,10 @@ GstreamerTest::GstreamerTest()
> >     >
> >     >  GstreamerTest::~GstreamerTest()
> >     >  {
> >     > -     if (libcameraSrc_ &&
> >     > -         !gst_object_has_as_ancestor(GST_OBJECT(libcameraSrc_),
> >     > -                                     GST_OBJECT(pipeline_)))
> >     > -             gst_object_unref(libcameraSrc_);
> >     >       if (pipeline_)
> >     >               gst_object_unref(pipeline_);
> >     > +     if (libcameraSrc_)
> >     > +             gst_object_unref(libcameraSrc_);
> >     >
> >     >       gst_deinit();
> >     >  }
> >     >
> >
> >
> > Regards,
> > /*Vedant Paranjape*/
>

Regards,
Vedant Paranjape

>
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