[openib-general] [PATCH] RDMA / IB CM: support immediately sending replies to received messages

[Or Gerlitz]

Sean Hefty wrote:
> Or Gerlitz wrote:
> Note that since the QP is in the RTS state, the IB COMM_EST event will 
> _not_ be generated.  This is the key difference between these 
> approaches.  The user would need to call rdma_establish when polling a 
> RX from the CQ.  Failure to do so would result in a connection failure 
> if the RTU were not received.  Calling rdma_establish would result in an 
> RDMA CM ESTABLISH event.

OK, thanks for further clarifying it.

>> OK, fair enough. Personally i preferred the patch set that implemented 
>> everything within the ib stack and just had this little requirement on 
>> the ULP to hold on with doing TX before getting the ESTABLISHED event, 
>> but this one makes sense as well.

> My preference is to provide whichever solution makes it easier on the 
> majority of the ULPs (ignoring spec changes at the moment).  I don't 
> know which fix ULPs will find easier to work with.  Maybe we can come up 
> with a compromise where we expose rdma_establish, but transitioning to 
> RTS before the REP is sent requires that the ULP do the transition...?

Indeed, lets see if we can get some input from the ULP people working on 
passive side / targets (eg NFS/Lustre/iSER/SDP).

If indeed there's a spec violation here, i think it makes much sense to 
have the ULP and not the CMA violate the spec, so as you suggest, this 
can be done by CMA consumers doing the QP transitions themselves.

Or.