From: Edward Hervey <edward@centricular.com>
Date: Tue, 14 Nov 2017 12:34:48 +0000 (+0100)
Subject: decodebin2: Don't take locks when deactivating pads
X-Git-Tag: 1.16.2~1002
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=77e5a71a1538e747b30c40b8b83cb2be42b02161;p=platform%2Fupstream%2Fgst-plugins-base.git

decodebin2: Don't take locks when deactivating pads

When deactivating pads, we need to ensure that the streaming threads
going through the pads we wish to deactivate can cleanly return.
Failure to do that would result in the streaming locks of those
pads never being released. The end result would be a deadlock
when stopping decodebin2.

In order to avoid that situation, release the "dyn" lock around
the deactivation code. And refactor the code to cope with the
list of blocked pads having potentially changed when re-acquiring
the lock.
---

diff --git a/gst/playback/gstdecodebin2.c b/gst/playback/gstdecodebin2.c
index 6e4a167..2ac51f8 100644
--- a/gst/playback/gstdecodebin2.c
+++ b/gst/playback/gstdecodebin2.c
@@ -5211,14 +5211,14 @@ find_sink_pad (GstElement * element)
 static void
 unblock_pads (GstDecodeBin * dbin)
 {
-  GList *tmp;
-
   GST_LOG_OBJECT (dbin, "unblocking pads");
 
-  for (tmp = dbin->blocked_pads; tmp; tmp = tmp->next) {
+  while (dbin->blocked_pads) {
+    GList *tmp = dbin->blocked_pads;
     GstDecodePad *dpad = (GstDecodePad *) tmp->data;
     GstPad *opad;
 
+    dbin->blocked_pads = g_list_delete_link (dbin->blocked_pads, tmp);
     opad = gst_ghost_pad_get_target (GST_GHOST_PAD_CAST (dpad));
     if (opad) {
 
@@ -5231,15 +5231,17 @@ unblock_pads (GstDecodeBin * dbin)
     }
 
     dpad->blocked = FALSE;
+
+    /* We release the dyn lock since we want to allow the streaming threads
+     * to properly stop and not be blocked in our various probes */
+    DYN_UNLOCK (dbin);
     /* make flushing, prevent NOT_LINKED */
     gst_pad_set_active (GST_PAD_CAST (dpad), FALSE);
-    gst_object_unref (dpad);
+    DYN_LOCK (dbin);
+
     GST_DEBUG_OBJECT (dpad, "unblocked");
+    gst_object_unref (dpad);
   }
-
-  /* clear, no more blocked pads */
-  g_list_free (dbin->blocked_pads);
-  dbin->blocked_pads = NULL;
 }
 
 static void