Fix race-condition/deadlock, plugin-copy while rolling

[ardour.git] / libs / ardour / session.cc

diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 228c52ef08d59c2c3d00d471d5a62507d7b0a6d9..da4421d4a2d92b9f9a428b8d72d2d3a7f1d24334 100644 (file)
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -6944,6 +6944,17 @@ Session::update_latency_compensation (bool force_whole_graph)
        if (_state_of_the_state & (InitialConnecting|Deletion)) {
                return;
        }
+       /* this lock is not usually contended, but under certain conditions,
+        * update_latency_compensation may be called concurrently.
+        * e.g. drag/drop copy a latent plugin while rolling.
+        * GUI thread (via route_processors_changed) and
+        * auto_connect_thread_run may race.
+        */
+       Glib::Threads::Mutex::Lock lx (_update_latency_lock, Glib::Threads::TRY_LOCK);
+       if (!lx.locked()) {
+               /* no need to do this twice */
+               return;
+       }
 
        bool some_track_latency_changed = update_route_latency (false, false);