[openib-general] Re: [PATCH] [uCM] user specified context in CM events + new test program

[Steve Wooding]

Hi Sean,

I've just starting looking into IB connection establishment and I was 
wondering what the ib_cm_init_qp_attr() function actually does. Studying 
the MindShare IB book, it talks about exchanging the QPNs, pSNs etc., 
via the REQ and REP messages. However, looking at your cmpost.c example, 
I see, for exmaple, that in the req handler the event containing the REQ 
message is never actually used when modyfing the QP to RTR. The 
ib_cm_init_qp_attr() function is used instead. Does the info in the REQ 
message get read in kernel space?

May you could expand a bit on the description of ib_cm_init_qp_attr() 
function.

Thanks a lot.

Steve.



Sean Hefty wrote:

The following patch:

* Adds user specified context to all uCM events.  Users will not retrieve
  any events associated with the context after destroying the corresponding
  cm_id.
* Provides the ib_cm_init_qp_attr() call to userspace clients of the CM.
  This call may be used to set QP attributes properly before modifying 
the QP.
* Fixes some error handling synchronization and cleanup issues.
* Performs some minor code cleanup.
* Replaces the ucm_simple test program with a userspace version of cmpost.
  The userspace version of cmpost uses the uAT interface to retrieve path
  records based on a remote host name, establishes a connection over a QP,
  and performs some simple message passing between the nodes.