From 75222a62c5924e0953a8f966b07a44a463af4718 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Laval?= <jeremie.laval@gmail.com>
Date: Mon, 23 Jul 2012 12:48:40 +0100
Subject: [PATCH] [corlib] Linked token callback to the proxy
 CancellationTokenSource shouldn't throw ODE in concurrent situations.

---
 .../CancellationTokenSource.cs                | 13 ++++++++-
 .../CancellationTokenSourceTest.cs            | 27 +++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/mcs/class/corlib/System.Threading/CancellationTokenSource.cs b/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
index b6668313257..ac1461110ea 100644
--- a/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
+++ b/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
@@ -158,6 +158,17 @@ namespace System.Threading
 				throw new AggregateException (exceptions);
 		}
 
+		/* This is the callback registered on linked tokens
+		 * so that they don't throw an ODE if the callback
+		 * is called concurrently with a Dispose
+		 */
+		void SafeLinkedCancel ()
+		{
+			try {
+				Cancel ();
+			} catch (ObjectDisposedException) {}
+		}
+
 #if NET_4_5
 		public void CancelAfter (TimeSpan delay)
 		{
@@ -199,7 +210,7 @@ namespace System.Threading
 				throw new ArgumentException ("Empty tokens array");
 
 			CancellationTokenSource src = new CancellationTokenSource ();
-			Action action = src.Cancel;
+			Action action = src.SafeLinkedCancel;
 			var registrations = new List<CancellationTokenRegistration> (tokens.Length);
 
 			foreach (CancellationToken token in tokens) {
diff --git a/mcs/class/corlib/Test/System.Threading/CancellationTokenSourceTest.cs b/mcs/class/corlib/Test/System.Threading/CancellationTokenSourceTest.cs
index e8a6e3a15d5..e33802c431a 100644
--- a/mcs/class/corlib/Test/System.Threading/CancellationTokenSourceTest.cs
+++ b/mcs/class/corlib/Test/System.Threading/CancellationTokenSourceTest.cs
@@ -33,6 +33,7 @@ using System;
 using System.Threading;
 using NUnit.Framework;
 using System.Threading.Tasks;
+using MonoTests.System.Threading.Tasks;
 
 namespace MonoTests.System.Threading
 {
@@ -413,6 +414,32 @@ namespace MonoTests.System.Threading
 
 			Assert.IsTrue (canceled, "#3");
 		}
+
+		[Test]
+		public void ConcurrentCancelLinkedTokenSourceWhileDisposing ()
+		{
+			ParallelTestHelper.Repeat (delegate {
+				var src = new CancellationTokenSource ();
+				var linked = CancellationTokenSource.CreateLinkedTokenSource (src.Token);
+				var cntd = new CountdownEvent (2);
+
+				var t1 = new Thread (() => {
+					if (!cntd.Signal ())
+						cntd.Wait ();
+					src.Cancel ();
+				});
+				var t2 = new Thread (() => {
+					if (!cntd.Signal ())
+						cntd.Wait ();
+					linked.Dispose ();
+				});
+
+				t1.Start ();
+				t2.Start ();
+				t1.Join (500);
+				t2.Join (500);
+				}, 500);
+		}
 	}
 }
 
-- 
2.25.1