[openib-general] [PATCH] [RFC] RDMA generic CMA updates

[Sean Hefty]

James Lentini wrote:
>>>I expect that the IB_CM_REQ_RECEIVED callback will be confusing to 
>>>ULPs. The ULP will receive a new cma_id with an old context value. 
>>>If the ULP wanted to make an adjustments to the cma_id that 
>>>received the request, it would need to store a reference to it in 
>>>the old cma_id's context value. I suggest you make the new cma_id 
>>>part of the event data (see patch below).
>>
>>The new cma_id must be used after the REQ is received, so I wanted to make
>>that clear.  There's not much that a user can do with the listening cma_id
>>from within the callback; since it cannot be destroyed from the callback
>>itself. This is a fairly minor issue that we can discuss more.
> 
> Fair enough. A comment that says the callback context is not strictly 
> tied to the cma_id would help here.

The IB CM does this a little differently that your proposal.  It returns the new 
cm_id in the callback, with a reference to the listen_id in the event.  For 
consistency, we may want to match this model.

With the CMA, I took out the listen_id, assuming that the user could get to it 
using the returned context.  I see your point about the context being confusing. 
  Another approach is to return the context directly in the callback.

Note that nothing prevents the user from changing the context stored with a 
cma_id.  It's only by default that a new cma_id is created with a context value 
equal to that of the listening request.

- Sean