diff --git a/validate/gst/qa/gst-qa-pad-monitor.c b/validate/gst/qa/gst-qa-pad-monitor.c
index 3f4bccc731..18b029e078 100644
--- a/validate/gst/qa/gst-qa-pad-monitor.c
+++ b/validate/gst/qa/gst-qa-pad-monitor.c
@@ -44,6 +44,43 @@ G_DEFINE_TYPE_WITH_CODE (GstQaPadMonitor, gst_qa_pad_monitor,
 #define PAD_IS_IN_PUSH_MODE(p) ((p)->mode == GST_ACTIVATE_PUSH)
 #define PENDING_FIELDS "pending-fields"
 
+/*
+ * Locking the parent should always be done before locking the
+ * pad-monitor to prevent deadlocks in case another monitor from
+ * another pad on the same element starts an operation that also
+ * requires locking itself and some other monitors from internally
+ * linked pads.
+ *
+ * An example:
+ * An element has a sink and a src pad. Some test starts running at sinkpad
+ * and it locks the parent, and then it locks itself. In case it needs to get
+ * some information from the srcpad, it is able to lock the srcpad and get it
+ * because the srcpad should never lock itself before locking the parent (which
+ * it won't be able as sinkpad already locked it).
+ *
+ * As a side one, it is possible that srcpad locks itself without locking the
+ * parent in case it wants to do a check that won't need to use other internally
+ * linked pads (sinkpad). But in this case it might lock and unlock freely without
+ * causing deadlocks.
+ */
+#define GST_QA_PAD_MONITOR_PARENT_LOCK(m)                  \
+G_STMT_START {                                             \
+  if (G_LIKELY (GST_QA_MONITOR_GET_PARENT (m))) {          \
+    GST_QA_MONITOR_LOCK (GST_QA_MONITOR_GET_PARENT (m));   \
+  } else {                                                 \
+    GST_WARNING_OBJECT (m, "No parent found, can't lock"); \
+  }                                                        \
+} G_STMT_END
+
+#define GST_QA_PAD_MONITOR_PARENT_UNLOCK(m)                  \
+G_STMT_START {                                               \
+  if (G_LIKELY (GST_QA_MONITOR_GET_PARENT (m))) {            \
+    GST_QA_MONITOR_UNLOCK (GST_QA_MONITOR_GET_PARENT (m));   \
+  } else {                                                   \
+    GST_WARNING_OBJECT (m, "No parent found, can't unlock"); \
+  }                                                          \
+} G_STMT_END
+
 typedef struct
 {
   GstClockTime timestamp;
@@ -269,7 +306,7 @@ static gboolean
 gst_qa_pad_monitor_pad_should_proxy_othercaps (GstQaPadMonitor * monitor)
 {
   GstQaMonitor *parent = GST_QA_MONITOR_GET_PARENT (monitor);
-  /* We only know how to handle othercaps checks for decoders so far */
+  /* We only know how to handle othercaps checks for codecs so far */
   return GST_QA_ELEMENT_MONITOR_ELEMENT_IS_DECODER (parent) ||
       GST_QA_ELEMENT_MONITOR_ELEMENT_IS_ENCODER (parent);
 }
@@ -449,7 +486,6 @@ _parent_set_cb (GstObject * object, GstObject * parent, GstQaMonitor * monitor)
           GST_DEBUG_PAD_NAME (object)));
 }
 
-
 static void
 gst_qa_pad_monitor_dispose (GObject * object)
 {
@@ -572,12 +608,14 @@ gst_qa_pad_monitor_check_buffer_timestamp_in_received_range (GstQaPadMonitor *
         GST_DEBUG_OBJECT (monitor, "Checking pad %s:%s input timestamps",
             GST_DEBUG_PAD_NAME (otherpad));
         othermonitor = g_object_get_data ((GObject *) otherpad, "qa-monitor");
+        GST_QA_MONITOR_LOCK (othermonitor);
         if (gst_qa_pad_monitor_timestamp_is_in_received_range (othermonitor, ts)
             && gst_qa_pad_monitor_timestamp_is_in_received_range (othermonitor,
                 ts_end)) {
           done = TRUE;
           found = TRUE;
         }
+        GST_QA_MONITOR_UNLOCK (othermonitor);
         gst_object_unref (otherpad);
         has_one = TRUE;
         break;
@@ -702,9 +740,12 @@ gst_qa_pad_monitor_check_aggregated_return (GstQaPadMonitor * monitor,
           othermonitor = g_object_get_data ((GObject *) peerpad, "qa-monitor");
           if (othermonitor) {
             found_a_pad = TRUE;
+            GST_QA_MONITOR_LOCK (othermonitor);
             aggregated =
                 _combine_flows (aggregated, othermonitor->last_flow_return);
+            GST_QA_MONITOR_UNLOCK (othermonitor);
           }
+
           gst_object_unref (peerpad);
         }
         gst_object_unref (otherpad);
@@ -761,7 +802,9 @@ gst_qa_pad_monitor_otherpad_add_pending_serialized_event (GstQaPadMonitor *
           SerializedEventData *data = g_slice_new0 (SerializedEventData);
           data->timestamp = last_ts;
           data->event = gst_event_ref (event);
+          GST_QA_MONITOR_LOCK (othermonitor);
           g_ptr_array_add (othermonitor->serialized_events, data);
+          GST_QA_MONITOR_UNLOCK (othermonitor);
         }
         break;
       case GST_ITERATOR_RESYNC:
@@ -803,9 +846,11 @@ gst_qa_pad_monitor_otherpad_add_pending_field (GstQaPadMonitor * monitor,
       case GST_ITERATOR_OK:
         othermonitor = g_object_get_data ((GObject *) otherpad, "qa-monitor");
         if (othermonitor) {
+          GST_QA_MONITOR_LOCK (othermonitor);
           g_assert (othermonitor->pending_setcaps_fields != NULL);
           gst_structure_set_value (othermonitor->pending_setcaps_fields,
               field, v);
+          GST_QA_MONITOR_UNLOCK (othermonitor);
         }
         break;
       case GST_ITERATOR_RESYNC:
@@ -838,10 +883,12 @@ gst_qa_pad_monitor_otherpad_clear_pending_fields (GstQaPadMonitor * monitor)
       case GST_ITERATOR_OK:
         othermonitor = g_object_get_data ((GObject *) otherpad, "qa-monitor");
         if (othermonitor) {
+          GST_QA_MONITOR_LOCK (othermonitor);
           g_assert (othermonitor->pending_setcaps_fields != NULL);
           gst_structure_free (othermonitor->pending_setcaps_fields);
           othermonitor->pending_setcaps_fields =
               gst_structure_empty_new (PENDING_FIELDS);
+          GST_QA_MONITOR_UNLOCK (othermonitor);
         }
         break;
       case GST_ITERATOR_RESYNC:
@@ -874,12 +921,14 @@ gst_qa_pad_monitor_add_expected_newsegment (GstQaPadMonitor * monitor,
     switch (gst_iterator_next (iter, (gpointer *) & otherpad)) {
       case GST_ITERATOR_OK:
         othermonitor = g_object_get_data ((GObject *) otherpad, "qa-monitor");
+        GST_QA_MONITOR_LOCK (othermonitor);
         if (othermonitor->expected_segment) {
           GST_QA_MONITOR_REPORT_WARNING (othermonitor, FALSE, EVENT, EXPECTED,
               "expected newsegment event never pushed");
           gst_event_unref (othermonitor->expected_segment);
         }
         othermonitor->expected_segment = gst_event_ref (event);
+        GST_QA_MONITOR_UNLOCK (othermonitor);
         gst_object_unref (otherpad);
         break;
       case GST_ITERATOR_RESYNC:
@@ -1031,8 +1080,12 @@ gst_qa_pad_monitor_sink_event_check (GstQaPadMonitor * pad_monitor,
   }
 
   if (handler) {
+    GST_QA_MONITOR_UNLOCK (pad_monitor);
+    GST_QA_PAD_MONITOR_PARENT_UNLOCK (pad_monitor);
     gst_event_ref (event);
     ret = pad_monitor->event_func (pad, event);
+    GST_QA_PAD_MONITOR_PARENT_LOCK (pad_monitor);
+    GST_QA_MONITOR_LOCK (pad_monitor);
   }
 
   /* post checks */
@@ -1107,8 +1160,10 @@ gst_qa_pad_monitor_src_event_check (GstQaPadMonitor * pad_monitor,
   }
 
   if (handler) {
+    GST_QA_MONITOR_UNLOCK (pad_monitor);
     gst_event_ref (event);
     ret = pad_monitor->event_func (pad, event);
+    GST_QA_MONITOR_LOCK (pad_monitor);
   }
 
   /* post checks */
@@ -1136,15 +1191,24 @@ gst_qa_pad_monitor_chain_func (GstPad * pad, GstBuffer * buffer)
       g_object_get_data ((GObject *) pad, "qa-monitor");
   GstFlowReturn ret;
 
-  gst_qa_pad_monitor_check_first_buffer (pad_monitor, buffer);
+  GST_QA_MONITOR_LOCK (pad_monitor);
 
+  gst_qa_pad_monitor_check_first_buffer (pad_monitor, buffer);
   gst_qa_pad_monitor_update_buffer_data (pad_monitor, buffer);
 
+  GST_QA_MONITOR_UNLOCK (pad_monitor);
+
   ret = pad_monitor->chain_func (pad, buffer);
 
+  GST_QA_PAD_MONITOR_PARENT_LOCK (pad_monitor);
+  GST_QA_MONITOR_LOCK (pad_monitor);
+
   pad_monitor->last_flow_return = ret;
   gst_qa_pad_monitor_check_aggregated_return (pad_monitor, ret);
 
+  GST_QA_MONITOR_UNLOCK (pad_monitor);
+  GST_QA_PAD_MONITOR_PARENT_UNLOCK (pad_monitor);
+
   return ret;
 }
 
@@ -1153,6 +1217,10 @@ gst_qa_pad_monitor_sink_event_func (GstPad * pad, GstEvent * event)
 {
   GstQaPadMonitor *pad_monitor =
       g_object_get_data ((GObject *) pad, "qa-monitor");
+  gboolean ret;
+
+  GST_QA_PAD_MONITOR_PARENT_LOCK (pad_monitor);
+  GST_QA_MONITOR_LOCK (pad_monitor);
 
   if (GST_EVENT_IS_SERIALIZED (event)) {
     GstClockTime last_ts;
@@ -1168,8 +1236,12 @@ gst_qa_pad_monitor_sink_event_func (GstPad * pad, GstEvent * event)
         event, last_ts);
   }
 
-  return gst_qa_pad_monitor_sink_event_check (pad_monitor, event,
+  ret = gst_qa_pad_monitor_sink_event_check (pad_monitor, event,
       pad_monitor->event_func);
+
+  GST_QA_MONITOR_UNLOCK (pad_monitor);
+  GST_QA_PAD_MONITOR_PARENT_UNLOCK (pad_monitor);
+  return ret;
 }
 
 static gboolean
@@ -1177,9 +1249,13 @@ gst_qa_pad_monitor_src_event_func (GstPad * pad, GstEvent * event)
 {
   GstQaPadMonitor *pad_monitor =
       g_object_get_data ((GObject *) pad, "qa-monitor");
+  gboolean ret;
 
-  return gst_qa_pad_monitor_src_event_check (pad_monitor, event,
+  GST_QA_MONITOR_LOCK (pad_monitor);
+  ret = gst_qa_pad_monitor_src_event_check (pad_monitor, event,
       pad_monitor->event_func);
+  GST_QA_MONITOR_UNLOCK (pad_monitor);
+  return ret;
 }
 
 static gboolean
@@ -1220,6 +1296,9 @@ gst_qa_pad_monitor_buffer_probe (GstPad * pad, GstBuffer * buffer,
 {
   GstQaPadMonitor *monitor = udata;
 
+  GST_QA_PAD_MONITOR_PARENT_LOCK (monitor);
+  GST_QA_MONITOR_LOCK (monitor);
+
   gst_qa_pad_monitor_check_first_buffer (monitor, buffer);
   gst_qa_pad_monitor_update_buffer_data (monitor, buffer);
 
@@ -1249,6 +1328,8 @@ gst_qa_pad_monitor_buffer_probe (GstPad * pad, GstBuffer * buffer,
       }
     }
   }
+  GST_QA_MONITOR_UNLOCK (monitor);
+  GST_QA_PAD_MONITOR_PARENT_UNLOCK (monitor);
   return TRUE;
 }
 
@@ -1256,6 +1337,10 @@ static gboolean
 gst_qa_pad_monitor_event_probe (GstPad * pad, GstEvent * event, gpointer udata)
 {
   GstQaPadMonitor *monitor = GST_QA_PAD_MONITOR_CAST (udata);
+  gboolean ret;
+
+  GST_QA_PAD_MONITOR_PARENT_LOCK (monitor);
+  GST_QA_MONITOR_LOCK (monitor);
 
   if (GST_EVENT_IS_SERIALIZED (event)) {
     gint i;
@@ -1286,7 +1371,11 @@ gst_qa_pad_monitor_event_probe (GstPad * pad, GstEvent * event, gpointer udata)
 
   /* This so far is just like an event that is flowing downstream,
    * so we do the same checks as a sinkpad event handler */
-  return gst_qa_pad_monitor_sink_event_check (monitor, event, NULL);
+  ret = gst_qa_pad_monitor_sink_event_check (monitor, event, NULL);
+  GST_QA_MONITOR_UNLOCK (monitor);
+  GST_QA_PAD_MONITOR_PARENT_UNLOCK (monitor);
+
+  return ret;
 }
 
 static GstCaps *
@@ -1303,11 +1392,15 @@ gst_qa_pad_monitor_getcaps_func (GstPad * pad)
   }
 
   if (ret) {
+    /* We shouldn't need to lock the parent as this doesn't modify
+     * other monitors, just does some peer_pad_caps */
+    GST_QA_MONITOR_LOCK (pad_monitor);
     gst_qa_pad_monitor_check_caps_complete (pad_monitor, ret);
 
     if (GST_PAD_DIRECTION (pad) == GST_PAD_SINK) {
       gst_qa_pad_monitor_check_caps_fields_proxied (pad_monitor, ret);
     }
+    GST_QA_MONITOR_UNLOCK (pad_monitor);
   }
 
   return ret;
@@ -1321,6 +1414,9 @@ gst_qa_pad_monitor_setcaps_func (GstPad * pad, GstCaps * caps)
   gboolean ret = TRUE;
   GstStructure *structure;
 
+  GST_QA_PAD_MONITOR_PARENT_LOCK (pad_monitor);
+  GST_QA_MONITOR_LOCK (pad_monitor);
+
   if (caps) {
     structure = gst_caps_get_structure (caps, 0);
     if (gst_structure_n_fields (pad_monitor->pending_setcaps_fields)) {
@@ -1373,12 +1469,17 @@ gst_qa_pad_monitor_setcaps_func (GstPad * pad, GstCaps * caps)
   pad_monitor->pending_setcaps_fields =
       gst_structure_empty_new (PENDING_FIELDS);
 
+  GST_QA_MONITOR_UNLOCK (pad_monitor);
+  GST_QA_PAD_MONITOR_PARENT_UNLOCK (pad_monitor);
+
   if (pad_monitor->setcaps_func) {
     ret = pad_monitor->setcaps_func (pad, caps);
   }
 
+  GST_QA_PAD_MONITOR_PARENT_LOCK (pad_monitor);
   if (!ret)
     gst_qa_pad_monitor_otherpad_clear_pending_fields (pad_monitor);
+  GST_QA_PAD_MONITOR_PARENT_UNLOCK (pad_monitor);
 
   return ret;
 }