hp procurves in ring topology

Hey guys

This might seem a bit trivial but for whatever reason i'm a bit unsure if this will just work out the box.

I have a set of ~10 2920's installed at a customer site. We have been working on creating a ring topology for a while and now the last fiber has been put in place.. So I want to connect the ends to create the ring.

How do I make sure that the traffic is blocked in the right place? - I would want it to be blocked at the place I now connect the new fiber to. So my ring is completed physically, but use STP to keep the looping out.