// to the original namespace; otherwise leave the thread locked which
				// will force the runtime to scrap the current thread, that is maybe
				// not as optimal but at least always safe to do.
				runtime.UnlockOSThread()
			}
		}()

		return toRun()
	}

	var wg sync.WaitGroup
	wg.Add(1)

	// Start the callback in a new green thread so that if we later fail

	// Make sure we don't blow out m->g0 stack.
	for i := 0; i < 100000; i++ {
		testCallbackPanic(t)
	}
}

func testCallbackPanicLocked(t *testing.T) {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	if !lockedOSThread() {
		t.Fatal("runtime.LockOSThread didn't")
	}
	defer func() {
		s := recover()
		if s == nil {
			t.Fatal("did not panic")
		}
		if s.(string) != "callback panic" {

pkg runtime, func SetFinalizer(interface{}, interface{})
pkg runtime, func Stack([]uint8, bool) int
pkg runtime, func ThreadCreateProfile([]StackRecord) (int, bool)
pkg runtime, func UnlockOSThread()
pkg runtime, func Version() string
pkg runtime, method (*Func) Entry() uintptr
pkg runtime, method (*Func) FileLine(uintptr) (string, int)
pkg runtime, method (*Func) Name() string