fix deadlock caused by VCA=>VCA slaving and set_state()

1 files changed, 12 insertions, 7 deletions

diff --git a/libs/ardour/vca_manager.cc b/libs/ardour/vca_manager.cc
index c8e3a009e4..9a96dc8a38 100644
--- a/libs/ardour/vca_manager.cc
+++ b/libs/ardour/vca_manager.cc
@@ -140,13 +140,18 @@ VCAManager::set_state (XMLNode const& node, int version)
 	XMLNodeList const & children = node.children();
 	VCAList vcal;
 
-	{
-
-		Mutex::Lock lm (lock);
-
-		for (XMLNodeList::const_iterator i = children.begin(); i != children.end(); ++i) {
-			if ((*i)->name() == VCA::xml_node_name) {
-				boost::shared_ptr<VCA> vca = boost::shared_ptr<VCA> (new VCA (_session, **i, version));
+	for (XMLNodeList::const_iterator i = children.begin(); i != children.end(); ++i) {
+		if ((*i)->name() == VCA::xml_node_name) {
+			boost::shared_ptr<VCA> vca = boost::shared_ptr<VCA> (new VCA (_session, **i, version));
+
+			/* can't hold the lock for the entire loop,
+			 * because the new VCA maybe slaved and needs
+			 * to call back into us to set up its own
+			 * slave/master relationship
+			 */
+
+			{
+				Mutex::Lock lm (lock);
 				_vcas.push_back (vca);
 				vcal.push_back (vca);
 			}