[openib-general] possible oops when callingipoib_neigh_destructor while ipoib mod ule is down.

[Roland Dreier]

    Fab> Don't the neighbour structures get cleaned up when an
    Fab> interface goes down?  Can't the interface go down while the
    Fab> module has outstanding references?

The original issue was that neighbour structures can hang around after
an interface is unregistered.

An interface can be downed even if the module has a non-zero reference
count, of course.  But under 2.6, for a normal network interface, one
can rmmod the corresponding module at any time -- the interface is
brought down and the module is unloaded.  I'd prefer to preserve that,
rather than forcing the user to down all IPoIB interfaces and then
wait an arbitrarily long time for all neighbours to be freed before
unloading the IPoIB module.

 - Roland