SQL & PL/SQL

I have this stored procedure...

create or replace PROCEDURE USERINACTIVE_PROC (p_user_id IN number)
AS
--
--
v_mess varchar2(256);
v_code number;
BEGIN
update user_master
set status = 'I'
where user_id = p_user_id;

commit;

EXCEPTION
when others then
v_code := SQLCODE;
v_mess := SQLERRM;
--for debug
--dbms_output.PUT_LINE(v_mess);
rollback;
END;



Right now I can execute with 1 user_id, I want to be able to enter unlimited user id's like '55555','66666','77777'
Do I just change this..
where user_id = p_user_id;
to this..
where user_id IN ('p_user_id');

??
thanks for any help