v4l2bufferpool: Remove duplicate check

We were calling gst_v4l2_is_buffer_valid() before and inside
gst_v4l2_buffer_pool_qbuf() as we needed to access the group. The second
check failed since the writability of the buffer get inherited from the
GstMemory, which lead to pipeline failure. As we cannot avoid the extra
ref, it would be racy otherwise, just pass the group to _dbuf() so it
does not have to call gst_v4l2_is_buffer_valid() again.

https://bugzilla.gnome.org/show_bug.cgi?id=796692

diff --git a/sys/v4l2/gstv4l2bufferpool.c b/sys/v4l2/gstv4l2bufferpool.c
index a572293..aecdfdf 100644 (file)
--- a/sys/v4l2/gstv4l2bufferpool.c
+++ b/sys/v4l2/gstv4l2bufferpool.c
@@ -1057,18 +1057,13 @@ no_buffers:
 }
 
 static GstFlowReturn
-gst_v4l2_buffer_pool_qbuf (GstV4l2BufferPool * pool, GstBuffer * buf)
+gst_v4l2_buffer_pool_qbuf (GstV4l2BufferPool * pool, GstBuffer * buf,
+    GstV4l2MemoryGroup * group)
 {
-  GstV4l2MemoryGroup *group = NULL;
   const GstV4l2Object *obj = pool->obj;
   GstClockTime timestamp;
   gint index;
 
-  if (!gst_v4l2_is_buffer_valid (buf, &group)) {
-    GST_ERROR_OBJECT (pool, "invalid buffer %p", buf);
-    return GST_FLOW_ERROR;
-  }
-
   index = group->buffer.index;
 
   if (pool->buffers[index] != NULL)
@@ -1415,7 +1410,7 @@ gst_v4l2_buffer_pool_release_buffer (GstBufferPool * bpool, GstBuffer * buffer)
             /* queue back in the device */
             if (pool->other_pool)
               gst_v4l2_buffer_pool_prepare_buffer (pool, buffer, NULL);
-            if (gst_v4l2_buffer_pool_qbuf (pool, buffer) != GST_FLOW_OK)
+            if (gst_v4l2_buffer_pool_qbuf (pool, buffer, group) != GST_FLOW_OK)
               pclass->release_buffer (bpool, buffer);
           } else {
             /* Simply release invalide/modified buffer, the allocator will
@@ -1915,9 +1910,13 @@ gst_v4l2_buffer_pool_process (GstV4l2BufferPool * pool, GstBuffer ** buf)
               gst_buffer_unref (to_queue);
               goto prepare_failed;
             }
+
+            /* retreive the group */
+            gst_v4l2_is_buffer_valid (to_queue, &group);
           }
 
-          if ((ret = gst_v4l2_buffer_pool_qbuf (pool, to_queue)) != GST_FLOW_OK)
+          if ((ret = gst_v4l2_buffer_pool_qbuf (pool, to_queue, group))
+              != GST_FLOW_OK)
             goto queue_failed;
 
           /* if we are not streaming yet (this is the first buffer, start