// Make sure panic during callback unwinds properly.
	if lockedOSThread() {
		t.Fatal("locked OS thread on entry to TestCallbackPanic")
	}
	defer func() {
		s := recover()
		if s == nil {
			t.Fatal("did not panic")
		}
		if s.(string) != "callback panic" {
			t.Fatal("wrong panic:", s)
		}
		if lockedOSThread() {
			t.Fatal("locked OS thread on exit from TestCallbackPanic")
		}
	}()

		for {
			select {
			case <-stop:
				return
			case <-time.After(time.Millisecond * 100):
			}
		}
	}()
	defer close(stop)

	for i := 0; i < 1000; i++ {
		if !C.Ctid() {
			t.Fatalf("cgo has not locked OS thread")
		}
	}