[Bug 794773] New: buffer: gst_buffer_copy_into should not copy parent buffer metas when doing a deep copy

[GStreamer (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=794773

            Bug ID: 794773
           Summary: buffer: gst_buffer_copy_into should not copy parent
                    buffer metas when doing a deep copy
    Classification: Platform
           Product: GStreamer
           Version: git master
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: gstreamer (core)
          Assignee: gstreamer-bugs at lists.freedesktop.org
          Reporter: p.zabel at pengutronix.de
        QA Contact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---

Created attachment 370250
  --> https://bugzilla.gnome.org/attachment.cgi?id=370250&action=edit
buffer: drop parent meta in deep copy

The purpose of a deep buffer copy is to be able to release the source
buffer and all its dependencies. Attaching the parent buffer meta to
the newly created deep copy needlessly keeps holding a reference to the
parent buffer.

Without the attached patch, a v4l2h264dec ! glimagesink pipeline fails to
decode h.264 streams that change format mid-stream because the glimagesink
fails to release all DMABuf buffers to the v4l2videodec when asked to,
even though it tries by making a deep copy of its last buffer and then
releasing it:

 LOG               GST_BUFFER gstbuffer.c:799:gst_buffer_new: new 0x73b19408
 LOG               GST_BUFFER gstbuffer.c:515:gst_buffer_copy_into: copy
0x73b18d28 to 0x73b19408, offset 0-114688/114688
 LOG            glbasetexture gstglmemory.c:159:_calculate_unpack_length: Found
alignment of 8 based on width (with plane width:224, plane stride:896 and pixel
stride:4. RU8(224*4) = 896)
 DEBUG           glbasememory gstglbasememory.c:178:gst_gl_base_memory_init:
new GL buffer memory:0x7250bc40 size:114688
 DEBUG          glbasetexture gstglmemory.c:340:gst_gl_memory_init: new GL
texture context:<glcontextegl0> memory:0x7250bc40 target:2D format:6408
dimensions:224x128 stride:896 size:114688
 LOG             glbasememory gstglbasememory.c:259:_map_data_gl: mapping mem
0x7250bc40 flags 20002
 LOG             glbasememory gstglbasememory.c:259:_map_data_gl: mapping mem
0x728e3e78 flags 20001
 LOG            glbasetexture gstglmemory.c:676:gst_gl_memory_copy_teximage:
copying memory 0x728e3e78, tex 2 into texture 146
 LOG             glbasememory gstglbasememory.c:338:_unmap_data_gl: unmapping
mem 0x728e3e78 flags 20001
 LOG             glbasememory gstglbasememory.c:338:_unmap_data_gl: unmapping
mem 0x7250bc40 flags 20002
 LOG               GST_BUFFER gstbuffer.c:414:_memory_add: buffer 0x73b19408,
idx -1, mem 0x7250bc40
 DEBUG             GST_BUFFER gstbuffer.c:2201:gst_buffer_add_meta: alloc
metadata 0x73b1747c (GstParentBufferMeta) of size 12
 DEBUG             GST_BUFFER gstbuffer.c:2201:gst_buffer_add_meta: alloc
metadata 0x73b1b044 (GstGLSyncMeta) of size 52
 LOG               glsyncmeta gstglsyncmeta.c:300:_gst_gl_sync_meta_transform:
copying sync meta 0x72506484 into 0x73b1b044
 LOG               glsyncmeta gstglsyncmeta.c:108:_default_copy: copy sync
object (nil) from meta 0x72506484 to 0x73b1b044
 LOG               glsyncmeta gstglsyncmeta.c:188:_set_sync_point: setting sync
point 0x72506484
 DEBUG             GST_BUFFER gstbuffer.c:2201:gst_buffer_add_meta: alloc
metadata 0x73b1b084 (GstGLSyncMeta) of size 52
 LOG               glsyncmeta gstglsyncmeta.c:300:_gst_gl_sync_meta_transform:
copying sync meta 0x73b16d4c into 0x73b1b084
 LOG               glsyncmeta gstglsyncmeta.c:108:_default_copy: copy sync
object (nil) from meta 0x73b16d4c to 0x73b1b084
 LOG               glsyncmeta gstglsyncmeta.c:188:_set_sync_point: setting sync
point 0x73b16d4c
 DEBUG             GST_BUFFER gstbuffer.c:2201:gst_buffer_add_meta: alloc
metadata 0x73b0190c (GstVideoMeta) of size 76
 LOG               GST_BUFFER gstbuffer.c:710:_gst_buffer_dispose: release
0x73b18d28 to pool 0x73b230e0
 DEBUG             GST_BUFFER gstbuffer.c:2383:gst_buffer_foreach_meta: remove
metadata 0x73206484 (GstParentBufferMeta)
 DEBUG             GST_BUFFER gstbuffer.c:2383:gst_buffer_foreach_meta: remove
metadata 0x72506484 (GstGLSyncMeta)
 LOG               glsyncmeta gstglsyncmeta.c:316:_free_gl_sync_meta: free sync
meta 0x72506484
 LOG               bufferpool
gstbufferpool.c:1284:default_release_buffer:<glbufferpool0> released buffer
0x73b18d28 0

Note that the GL buffer is released, but not the parent DMABuf, which
is added to the new copy via GstParentBufferMeta. It is outstanding from
the v4l2videodec src bufferpool and keeps it from stopping properly:

 DEBUG             GST_BUFFER
gstbuffer.c:1375:gst_buffer_is_memory_range_writable: idx 0, length -1
 ERROR           v4l2videodec
gstv4l2videodec.c:271:gst_v4l2_video_dec_set_format:<v4l2h264dec0> Stop capture

 DEBUG                   v4l2
gstv4l2object.c:4326:gst_v4l2_object_stop:<v4l2h264dec0:src> stopping
 DEBUG                   v4l2
gstv4l2object.c:4334:gst_v4l2_object_stop:<v4l2h264dec0:src> deactivating pool
 LOG               bufferpool
gstbufferpool.c:506:gst_buffer_pool_set_active:<v4l2h264dec0:pool:src> active 0
 LOG               bufferpool
gstbufferpool.c:538:gst_buffer_pool_set_active:<v4l2h264dec0:pool:src>
outstanding buffers 1

After this, the format change and stream restart fails in the
v4l2videodec.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.