pad: don't accept flush-stop on inactive pads

Inactive pads should at all times have the flushing flag set. This means
that when we get a flush-stop on an inactive pad we must ignore it.

On sinkpads, make this more explicit. We used to not clear the flush
flag but remove the events and then return an error because the flushing
flag was set. Now just simply refuse the event without doing anything.

On srcpads, check that we are trying to push a flush-stop event and
refuse it. We would allow this and mark the srcpad as non-flushing
anymore.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=735357

1 files changed, 29 insertions, 5 deletions

diff --git a/gst/gstpad.c b/gst/gstpad.c
index bae09814e4..adb44ffca0 100644
--- a/gst/gstpad.c
+++ b/gst/gstpad.c
@@ -4774,6 +4774,9 @@ gst_pad_push_event_unchecked (GstPad * pad, GstEvent * event,
       type |= GST_PAD_PROBE_TYPE_EVENT_FLUSH;
       break;
     case GST_EVENT_FLUSH_STOP:
+      if (G_UNLIKELY (!GST_PAD_IS_ACTIVE (pad)))
+        goto inactive;
+
       GST_PAD_UNSET_FLUSHING (pad);
 
       /* Remove sticky EOS events */
@@ -4862,6 +4865,12 @@ flushed:
     gst_event_unref (event);
     return GST_FLOW_FLUSHING;
   }
+inactive:
+  {
+    GST_DEBUG_OBJECT (pad, "flush-stop on inactive pad");
+    gst_event_unref (event);
+    return GST_FLOW_FLUSHING;
+  }
 probe_stopped:
   {
     GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_PENDING_EVENTS);
@@ -5064,17 +5073,22 @@ gst_pad_send_event_unchecked (GstPad * pad, GstEvent * event,
           "have event type %d (FLUSH_START)", GST_EVENT_TYPE (event));
 
       /* can't even accept a flush begin event when flushing */
-      if (GST_PAD_IS_FLUSHING (pad))
+      if (G_UNLIKELY (GST_PAD_IS_FLUSHING (pad)))
         goto flushing;
 
       GST_PAD_SET_FLUSHING (pad);
       GST_CAT_DEBUG_OBJECT (GST_CAT_EVENT, pad, "set flush flag");
       break;
     case GST_EVENT_FLUSH_STOP:
-      if (G_LIKELY (GST_PAD_MODE (pad) != GST_PAD_MODE_NONE)) {
-        GST_PAD_UNSET_FLUSHING (pad);
-        GST_CAT_DEBUG_OBJECT (GST_CAT_EVENT, pad, "cleared flush flag");
-      }
+      /* we can't accept flush-stop on inactive pads else the flushing flag
+       * would be cleared and it would look like the pad can accept data.
+       * Also, some elements restart a streaming thread in flush-stop which we
+       * can't allow on inactive pads */
+      if (G_UNLIKELY (!GST_PAD_IS_ACTIVE (pad)))
+        goto inactive;
+
+      GST_PAD_UNSET_FLUSHING (pad);
+      GST_CAT_DEBUG_OBJECT (GST_CAT_EVENT, pad, "cleared flush flag");
       /* Remove pending EOS events */
       GST_LOG_OBJECT (pad, "Removing pending EOS and SEGMENT events");
       remove_event_by_type (pad, GST_EVENT_EOS);
@@ -5189,6 +5203,16 @@ flushing:
     gst_event_unref (event);
     return GST_FLOW_FLUSHING;
   }
+inactive:
+  {
+    GST_OBJECT_UNLOCK (pad);
+    if (need_unlock)
+      GST_PAD_STREAM_UNLOCK (pad);
+    GST_CAT_INFO_OBJECT (GST_CAT_EVENT, pad,
+        "Received flush-stop on inactive pad. Discarding");
+    gst_event_unref (event);
+    return GST_FLOW_FLUSHING;
+  }
 eos:
   {
     GST_OBJECT_UNLOCK (pad);