From ff9a78196c032588d75b99f6dfb74817bde196c2 Mon Sep 17 00:00:00 2001
From: Stian Selnes <stian@pexip.com>
Date: Wed, 5 Aug 2015 10:07:50 +0200
Subject: [PATCH] harness: Fix race for gst_harness_element_ref

In order for gst_harness_new_full to be MT-safe the increase and
decrease of HARNESS_REF must be MT-safe. This allows for creating
multiple harnesses from different threads wrapping the same element.

https://bugzilla.gnome.org/show_bug.cgi?id=754661
---
 libs/gst/check/gstharness.c   | 17 ++++++++++++++---
 tests/check/libs/gstharness.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/libs/gst/check/gstharness.c b/libs/gst/check/gstharness.c
index cfaa5861a0..6a8cde3c84 100644
--- a/libs/gst/check/gstharness.c
+++ b/libs/gst/check/gstharness.c
@@ -433,7 +433,10 @@ gst_harness_src_query (GstPad * pad, GstObject * parent, GstQuery * query)
 static void
 gst_harness_element_ref (GstHarness * h)
 {
-  guint *data = g_object_get_data (G_OBJECT (h->element), HARNESS_REF);
+  guint *data;
+
+  GST_OBJECT_LOCK (h->element);
+  data = g_object_get_data (G_OBJECT (h->element), HARNESS_REF);
   if (data == NULL) {
     data = g_new0 (guint, 1);
     *data = 1;
@@ -441,15 +444,23 @@ gst_harness_element_ref (GstHarness * h)
   } else {
     (*data)++;
   }
+  GST_OBJECT_UNLOCK (h->element);
 }
 
 static guint
 gst_harness_element_unref (GstHarness * h)
 {
-  guint *data = g_object_get_data (G_OBJECT (h->element), HARNESS_REF);
+  guint *data;
+  guint ret;
+
+  GST_OBJECT_LOCK (h->element);
+  data = g_object_get_data (G_OBJECT (h->element), HARNESS_REF);
   g_assert (data != NULL);
   (*data)--;
-  return *data;
+  ret = *data;
+  GST_OBJECT_UNLOCK (h->element);
+
+  return ret;
 }
 
 static void
diff --git a/tests/check/libs/gstharness.c b/tests/check/libs/gstharness.c
index 67abab2aa2..ef55afc6e2 100644
--- a/tests/check/libs/gstharness.c
+++ b/tests/check/libs/gstharness.c
@@ -22,6 +22,33 @@
 #include <gst/check/gstcheck.h>
 #include <gst/check/gstharness.h>
 
+static void
+create_destroy_element_harness (gpointer data, gpointer user_data)
+{
+  GstElement * element = user_data;
+  GstHarness * h = gst_harness_new_with_element (element, NULL, NULL);
+  gst_harness_teardown (h);
+}
+
+GST_START_TEST(test_harness_element_ref)
+{
+  GstHarness * h = gst_harness_new ("identity");
+  GstHarnessThread * threads[100];
+  gint i;
+
+  for (i = 0; i < G_N_ELEMENTS (threads); i++)
+    threads[i] = gst_harness_stress_custom_start (h, NULL,
+        create_destroy_element_harness, h->element, 0);
+  for (i = 0; i < G_N_ELEMENTS (threads); i++)
+    gst_harness_stress_thread_stop (threads[i]);
+
+  fail_unless_equals_int (G_OBJECT (h->element)->ref_count, 1);
+
+  gst_harness_teardown (h);
+}
+GST_END_TEST;
+
+
 GST_START_TEST(test_src_harness)
 {
   GstHarness * h = gst_harness_new ("identity");
@@ -88,6 +115,7 @@ gst_harness_suite (void)
 
   suite_add_tcase (s, tc_chain);
 
+  tcase_add_test (tc_chain, test_harness_element_ref);
   tcase_add_test (tc_chain, test_src_harness);
   tcase_add_test (tc_chain, test_src_harness_no_forwarding);