Correct CancellationTokenSource locking. Fix #3756.

diff --git a/mcs/class/corlib/System.Threading/CancellationTokenSource.cs b/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
index a6dfda4438841c93b353aad9fa9e6b9de71d99ee..76503e7dc5f3abd780145e24c13c6dff7cc0ecb0 100644 (file)
--- a/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
+++ b/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
@@ -126,7 +126,7 @@ namespace System.Threading
                        
                        List<Exception> exceptions = null;
                        
-                       lock (callbacks) {
+                       lock (syncRoot) {
                                try {
                                        foreach (var item in callbacks) {
                                                if (throwOnFirstException) {