1 files changed, 18 insertions, 0 deletions
diff --git a/libgo/go/sync/mutex_test.go b/libgo/go/sync/mutex_test.go
index 98c1bf2..cca0986 100644
--- a/libgo/go/sync/mutex_test.go
+++ b/libgo/go/sync/mutex_test.go
@@ -60,6 +60,12 @@ func BenchmarkContendedSemaphore(b *testing.B) {
 
 func HammerMutex(m *Mutex, loops int, cdone chan bool) {
 	for i := 0; i < loops; i++ {
+		if i%3 == 0 {
+			if m.TryLock() {
+				m.Unlock()
+			}
+			continue
+		}
 		m.Lock()
 		m.Unlock()
 	}
@@ -71,7 +77,19 @@ func TestMutex(t *testing.T) {
 		t.Logf("got mutexrate %d expected 0", n)
 	}
 	defer runtime.SetMutexProfileFraction(0)
+
 	m := new(Mutex)
+
+	m.Lock()
+	if m.TryLock() {
+		t.Fatalf("TryLock succeeded with mutex locked")
+	}
+	m.Unlock()
+	if !m.TryLock() {
+		t.Fatalf("TryLock failed with mutex unlocked")
+	}
+	m.Unlock()
+
 	c := make(chan bool)
 	for i := 0; i < 10; i++ {
 		go HammerMutex(m, 1000, c)