if ((undo_list != NULL) && (atomic_read(&undo_list->refcnt) != 1))
if (undo_list)
static inline void unlock_semundo(void){	struct sem_undo_list *undo_list;	undo_list = current->sysvsem.undo_list;	if ((undo_list != NULL) && (atomic_read(&undo_list->refcnt) != 1))		spin_unlock(&undo_list->lock);}