Re: Problem with RDMA device removal architecture

Roland Dreier
2010-03-26T17:08:10Z

> In other words, I think we want the ucma context to stay around until
> the application destroys it (via explicit means or via exit). But
> the rdma_cm_id gets destroyed immediately upon receiving a
> DEVICE_REMOVE event.

Yes. The RDMA CM is somewhat easier, but I think the basic idea should
be that ucma internally detaches the userspace context from anything
that is holding a device reference, and marks the context as "dead"
(only valid operation is destroying it).

uverbs is trickier, because a userspace process will typically have some
hardware resources directly mmap'ed. We need a way to "revoke" that
mmap and have it point at a dummy page until userspace releases it --
and last I looked I wasn't sure how to do that.

- R.
--
Roland Dreier <rolandd-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
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