[openib-general] RFC fix for userspace rdma cm crashes

[Sean Hefty]

> Does this affect kernel rdma cm users too in some way?  If not, then
> perhaps the place to fix it is in userspace.

This doesn't affect the kernel rdma_cm.  The fix can either go into the rdma_ucm 
(not rdma_cm), or librdmacm, either of which limit the impact to userspace 
clients only.

Here's one issue with putting the fix in the librdmacm: there's no guarantee 
that a multi-threaded client will process the event for a new connection before 
the reject.  This makes me lean toward implementing the fix in the kernel, where 
the events are serialized.

- Sean