rt_write_lock
#define write_lock_nested(lock, subclass) rt_write_lock(((void)(subclass), (lock)))
rt_write_lock(rwlock);
rt_write_lock(rwlock);
rt_write_lock(lock); \
extern void rt_write_lock(rwlock_t *rwlock) __acquires(rwlock);
rt_write_lock(rwlock);
EXPORT_SYMBOL(rt_write_lock);