[openib-general] [RFC] [PATCH 2/7] ib_multicast 2.6.20: add ib_multicast module to track join requests from the same port

[Roland Dreier]

    Eitan> User level code can be run by root. It can access QP1 and
    Eitan> bypass your nice API.  Also you ignore current kernel
    Eitan> implementations that exist and already perform QP1 access
    Eitan> via the SA client code in the kernel.

root can already do anything at all so I don't think that's an issue.
We want a way for unprivileged userspace to be able to use multicast.
Usually I say "just use a privileged daemon in userspace" but I think
in this case we actually need coordination between the kernel and
userspace to track _all_ multicast joins, so it does make sense for
this to be in the kernel.

kernel code can always be ported as part of the merge, and in fact
that's exactly what Sean did for the only user of multicast stuff,
namely IPoIB.

 - R.