Locks, more complicated than I orginally thought

Hello all,
I am working on that SHOW locks todo item, that lists all
current locks. This seems a bit tricky as there is no central
place where one could reference a lock, appears they are just
called.
Now my question is that, would it be "ok" to have a locks
linked list that held all the locks, and their information
in the function calls that make the lock? Or is there some
other method that would be more suitable for this. Seeking
the advice of experience with this sorta thing (if there is
anyone, heh).
If there was this one master linked list, holding all the
lock information, then making a SHOW locks like command would
be a snap!
Also do you think this sort of action would slow the database
down too much to even warrent doing it this way? Of course i
personally havent tested yet, so have no figures, but you
guys know more about database programming and postgresql.

Thanks,
Chris