splitmuxsrc: Fix some deadlock conditions and a crash

When switching the splitmuxsrc state back to NULL quickly, it
can encounter deadlocks shutting down the part readers that
are still starting up, or encounter a crash if the splitmuxsrc
cleaned up the parts before the async callback could run.

Taking the state lock to post async-start / async-done messages can
deadlock if the state change function is trying to shut down the
element, so use some finer grained locks for that.

4 files changed, 38 insertions, 12 deletions

diff --git a/gst/multifile/gstsplitmuxpartreader.c b/gst/multifile/gstsplitmuxpartreader.c
index 51a8635bd..77a1745c7 100644
--- a/gst/multifile/gstsplitmuxpartreader.c
+++ b/gst/multifile/gstsplitmuxpartreader.c
@@ -37,6 +37,9 @@ GST_DEBUG_CATEGORY_STATIC (splitmux_part_debug);
 #define SPLITMUX_PART_TYPE_LOCK(p) g_mutex_lock(&(p)->type_lock)
 #define SPLITMUX_PART_TYPE_UNLOCK(p) g_mutex_unlock(&(p)->type_lock)
 
+#define SPLITMUX_PART_MSG_LOCK(p) g_mutex_lock(&(p)->msg_lock)
+#define SPLITMUX_PART_MSG_UNLOCK(p) g_mutex_unlock(&(p)->msg_lock)
+
 typedef struct _GstSplitMuxPartPad
 {
   GstPad parent;
@@ -636,6 +639,7 @@ gst_splitmux_part_reader_init (GstSplitMuxPartReader * reader)
   g_cond_init (&reader->inactive_cond);
   g_mutex_init (&reader->lock);
   g_mutex_init (&reader->type_lock);
+  g_mutex_init (&reader->msg_lock);
 
   /* FIXME: Create elements on a state change */
   reader->src = gst_element_factory_make ("filesrc", NULL);
@@ -683,6 +687,7 @@ splitmux_part_reader_finalize (GObject * object)
   g_cond_clear (&reader->inactive_cond);
   g_mutex_clear (&reader->lock);
   g_mutex_clear (&reader->type_lock);
+  g_mutex_clear (&reader->msg_lock);
 
   g_free (reader->path);
 
@@ -694,12 +699,12 @@ do_async_start (GstSplitMuxPartReader * reader)
 {
   GstMessage *message;
 
-  GST_STATE_LOCK (reader);
+  SPLITMUX_PART_MSG_LOCK (reader);
   reader->async_pending = TRUE;
 
   message = gst_message_new_async_start (GST_OBJECT_CAST (reader));
   GST_BIN_CLASS (parent_class)->handle_message (GST_BIN_CAST (reader), message);
-  GST_STATE_UNLOCK (reader);
+  SPLITMUX_PART_MSG_UNLOCK (reader);
 }
 
 static void
@@ -707,7 +712,7 @@ do_async_done (GstSplitMuxPartReader * reader)
 {
   GstMessage *message;
 
-  GST_STATE_LOCK (reader);
+  SPLITMUX_PART_MSG_LOCK (reader);
   if (reader->async_pending) {
     message =
         gst_message_new_async_done (GST_OBJECT_CAST (reader),
@@ -717,7 +722,7 @@ do_async_done (GstSplitMuxPartReader * reader)
 
     reader->async_pending = FALSE;
   }
-  GST_STATE_UNLOCK (reader);
+  SPLITMUX_PART_MSG_UNLOCK (reader);
 }
 
 static void
diff --git a/gst/multifile/gstsplitmuxpartreader.h b/gst/multifile/gstsplitmuxpartreader.h
index 1659b6e92..78ecc6eb5 100644
--- a/gst/multifile/gstsplitmuxpartreader.h
+++ b/gst/multifile/gstsplitmuxpartreader.h
@@ -80,6 +80,7 @@ struct _GstSplitMuxPartReader
   GCond inactive_cond;
   GMutex lock;
   GMutex type_lock;
+  GMutex msg_lock;
 
   GstSplitMuxPartReaderPadCb get_pad_cb;
   gpointer cb_data;
diff --git a/gst/multifile/gstsplitmuxsrc.c b/gst/multifile/gstsplitmuxsrc.c
index 757f3bd7f..f8c27fb47 100644
--- a/gst/multifile/gstsplitmuxsrc.c
+++ b/gst/multifile/gstsplitmuxsrc.c
@@ -331,13 +331,13 @@ do_async_start (GstSplitMuxSrc * splitmux)
 {
   GstMessage *message;
 
-  GST_STATE_LOCK (splitmux);
+  SPLITMUX_SRC_MSG_LOCK (splitmux);
   splitmux->async_pending = TRUE;
 
   message = gst_message_new_async_start (GST_OBJECT_CAST (splitmux));
   GST_BIN_CLASS (parent_class)->handle_message (GST_BIN_CAST (splitmux),
       message);
-  GST_STATE_UNLOCK (splitmux);
+  SPLITMUX_SRC_MSG_UNLOCK (splitmux);
 }
 
 static void
@@ -345,7 +345,7 @@ do_async_done (GstSplitMuxSrc * splitmux)
 {
   GstMessage *message;
 
-  GST_STATE_LOCK (splitmux);
+  SPLITMUX_SRC_MSG_LOCK (splitmux);
   if (splitmux->async_pending) {
     message =
         gst_message_new_async_done (GST_OBJECT_CAST (splitmux),
@@ -355,7 +355,7 @@ do_async_done (GstSplitMuxSrc * splitmux)
 
     splitmux->async_pending = FALSE;
   }
-  GST_STATE_UNLOCK (splitmux);
+  SPLITMUX_SRC_MSG_UNLOCK (splitmux);
 }
 
 static GstStateChangeReturn
@@ -408,10 +408,14 @@ gst_splitmux_src_change_state (GstElement * element, GstStateChange transition)
 static void
 gst_splitmux_src_activate_first_part (GstSplitMuxSrc * splitmux)
 {
-  if (!gst_splitmux_src_activate_part (splitmux, 0, GST_SEEK_FLAG_NONE)) {
-    GST_ELEMENT_ERROR (splitmux, RESOURCE, OPEN_READ, (NULL),
-        ("Failed to activate first part for playback"));
+  SPLITMUX_SRC_LOCK (splitmux);
+  if (splitmux->running) {
+    if (!gst_splitmux_src_activate_part (splitmux, 0, GST_SEEK_FLAG_NONE)) {
+      GST_ELEMENT_ERROR (splitmux, RESOURCE, OPEN_READ, (NULL),
+          ("Failed to activate first part for playback"));
+    }
   }
+  SPLITMUX_SRC_UNLOCK (splitmux);
 }
 
 static GstBusSyncReply
@@ -887,6 +891,14 @@ gst_splitmux_src_start (GstSplitMuxSrc * splitmux)
   gchar **files;
   guint i;
 
+  SPLITMUX_SRC_LOCK (splitmux);
+  if (splitmux->running) {
+    /* splitmux is still running / stopping. We can't start again yet */
+    SPLITMUX_SRC_UNLOCK (splitmux);
+    return FALSE;
+  }
+  SPLITMUX_SRC_UNLOCK (splitmux);
+
   GST_DEBUG_OBJECT (splitmux, "Starting");
 
   g_signal_emit (splitmux, signals[SIGNAL_FORMAT_LOCATION], 0, &files);
@@ -980,7 +992,10 @@ gst_splitmux_src_stop (GstSplitMuxSrc * splitmux)
 
   GST_DEBUG_OBJECT (splitmux, "Stopping");
 
-  /* Stop and destroy all parts  */
+  SPLITMUX_SRC_UNLOCK (splitmux);
+
+  /* Stop and destroy all parts. We don't need the lock here,
+   * because all parts were created in _start()  */
   for (i = 0; i < splitmux->num_created_parts; i++) {
     if (splitmux->parts[i] == NULL)
       continue;
@@ -988,6 +1003,7 @@ gst_splitmux_src_stop (GstSplitMuxSrc * splitmux)
     g_object_unref (splitmux->parts[i]);
     splitmux->parts[i] = NULL;
   }
+  SPLITMUX_SRC_LOCK (splitmux);
 
   SPLITMUX_SRC_PADS_WLOCK (splitmux);
   pads_list = splitmux->pads;
diff --git a/gst/multifile/gstsplitmuxsrc.h b/gst/multifile/gstsplitmuxsrc.h
index 4c8f95cc0..8bb84a7a4 100644
--- a/gst/multifile/gstsplitmuxsrc.h
+++ b/gst/multifile/gstsplitmuxsrc.h
@@ -44,6 +44,7 @@ struct _GstSplitMuxSrc
   GstBin parent;
 
   GMutex lock;
+  GMutex msg_lock;
   gboolean     running;
 
   gchar       *location;  /* OBJECT_LOCK */
@@ -108,6 +109,9 @@ gboolean register_splitmuxsrc (GstPlugin * plugin);
 #define SPLITMUX_SRC_LOCK(s) g_mutex_lock(&(s)->lock)
 #define SPLITMUX_SRC_UNLOCK(s) g_mutex_unlock(&(s)->lock)
 
+#define SPLITMUX_SRC_MSG_LOCK(s) g_mutex_lock(&(s)->msg_lock)
+#define SPLITMUX_SRC_MSG_UNLOCK(s) g_mutex_unlock(&(s)->msg_lock)
+
 #define SPLITMUX_SRC_PADS_WLOCK(s) g_rw_lock_writer_lock(&(s)->pads_rwlock)
 #define SPLITMUX_SRC_PADS_WUNLOCK(s) g_rw_lock_writer_unlock(&(s)->pads_rwlock)
 #define SPLITMUX_SRC_PADS_RLOCK(s) g_rw_lock_reader_lock(&(s)->pads_rwlock)