__down_write_trylock
LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock,
int ret = __down_write_trylock(sem);
LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
LOCK_CONTENDED(sem, __down_write_trylock, __down_write);
if (LOCK_CONTENDED_RETURN(sem, __down_write_trylock,