[openib-general] Re: RDMA Generic Connection Management

[Roland Dreier]

    James> When scsi_remove_host() returns are you guaranteed that
    James> there are no SCSI calls into your code in progress (e.g. in
    James> srp_queuecommand)?

I think so.

    Roland> Yes, but what is the generic way?

    James> The generic way would be to handle this in a common
    James> layer. For the IB verbs + RDMA connection API to be as easy
    James> to use as the sockets API, then it needs to make this issue
    James> transparent.

I don't think the kernel design philosophy is to hide these sorts of
object lifetime issues from consumers.  And my real question is how
it's even possible to handle this efficiently in a generic layer.

If you want consumers to be able to ignore hotplug, then the generic
layer needs to handle device removal even in the middle of fast path
work request posting operations.  And I don't see how to do that
without changing to reference counted handles (from the current scheme
of directly using pointers).  And that's going to have a serious
performance impact that I don't think is worth it.

 - R.