[openib-general] RFC: detecting duplicate MAD requests

[Sean Hefty]

>There's still a window here depending on when free MAD is called versus
>when the response gets back to the original requester.

There are no issues in this case.  We just need to avoid having two responses
being sent at the same time.

>>  but I'm not sure if this would happen in practice.  A
>> second drawback is that the receive MAD would need to be kept around until
>the
>> send completed (as opposed to the send started).
>
>Is this to handle the case where free MAD is called prior to the send
>completing ? Is this on the response side only ?

The basic idea is that when a MAD with the response bit set is sent, a check is
made against a list received MADs that have been reported to the user.  If a
received MAD is found, it is removed from the list, and the response is sent.
If no request is found (e.g. the MAD had already been freed), then the send
fails.

- Sean