Index: include/tbb/internal/_flow_graph_impl.h
===================================================================
--- include/tbb/internal/_flow_graph_impl.h	(revision 10741)
+++ include/tbb/internal/_flow_graph_impl.h	(working copy)
@@ -518,8 +518,8 @@
         // as above, but call try_put_task instead, and return the last task we received (if any)
         /*override*/ task * try_put_task( const T &t ) {
             task * last_task = NULL;
-            bool upgraded = false;
-            typename my_mutex_type::scoped_lock l(this->my_mutex, false);
+            bool upgraded = true;
+            typename my_mutex_type::scoped_lock l(this->my_mutex, upgraded);
             typename my_successors_type::iterator i = this->my_successors.begin();
             while ( i != this->my_successors.end() ) {
                 task *new_task = (*i)->try_put_task(t);
@@ -560,8 +560,8 @@
         }
         
         /*override*/task *try_put_task( const T &t ) {
-            bool upgraded = false;
-            typename my_mutex_type::scoped_lock l(this->my_mutex, false);
+            bool upgraded = true;
+            typename my_mutex_type::scoped_lock l(this->my_mutex, upgraded);
             typename my_successors_type::iterator i = this->my_successors.begin();
             while ( i != this->my_successors.end() ) {
                 task *new_task = (*i)->try_put_task(t);
Index: include/tbb/flow_graph.h
===================================================================
--- include/tbb/flow_graph.h	(revision 10741)
+++ include/tbb/flow_graph.h	(working copy)
@@ -1828,10 +1828,12 @@
     }
 
     task *forward_task() {
-        spin_mutex::scoped_lock lock(my_mutex);
-        if ( my_count >= my_threshold )
-            return NULL;
-        ++my_count;
+        {
+            spin_mutex::scoped_lock lock(my_mutex);
+            if ( my_count >= my_threshold )
+                return NULL;
+            ++my_count;
+        }
         task * rtask = decrement_counter();
         return rtask;
     }