Basic critical sections question

[usenet@scriptoriumdesigns.com]

Suppose I have a multi-tasking system where different tasks may
execute a sequence like

  P1(A,B);
  P2(C,D);
  P3(E,F);

and I want to make this sequence a critical section.  What is the
typical Ada way to do this?  Would I wrap P1, P2 and P3 in a protected
object and call as follows (perhaps creating a record to hold A..F to
make things a bit cleaner)?

  PO.P(A,B,C,D,E,F);

Or if not that, what?  Thanks.