try_to_take_rt_mutex
int ret = try_to_take_rt_mutex(lock, current, NULL);
if (try_to_take_rt_mutex(lock, current, waiter)) {
if (try_to_take_rt_mutex(lock, current, NULL)) {
if (try_to_take_rt_mutex(lock, current, NULL)) {
if (try_to_take_rt_mutex(lock, current, &waiter)) {
if (try_to_take_rt_mutex(lock, task, NULL))
try_to_take_rt_mutex(lock, current, waiter);