[ofa-general] [RFC/PATCH 2.6.24] ib/multicast: report errors on multicast groups if pkeys change

[Roland Dreier]

 > Pkey changes can invalidate multicast groups.  Report errors on any
 > multicast group affected by a pkey change.

I'm missing some context here.  What is the issue that's being fixed
here?  What's the impact of not having this patch?  (ie does this need
to go into 2.6.24?  Also 2.6.23.x?  Or is 2.6.25 OK?)

 - R.