//Since you have pointers, you have to use double pointers to change pointer where it points to (maybe sounds confusing)
//Declaration in kernel.c
void getLists(struct list** l1, struct list** l2, ........) {
    *l1 = Readylist1;
    *l2 = Readylist2
}

//Usage in main.
struct list* l1, *l2;

//Get pointers
getLists(&l1, &l2);