[openib-general] APM: QP migration state change when failover triggered by hw

[Venkatesh Babu]

>Babu, regarding the migration event that you are seeing, are you sure that it 
>is from the migration transition that does not occur?  Possibly, the 
>problematic transition is the second one, which occurs after specifying a new 
>alternate path and rearming APM?
>  
>
   I am sure that it is when the cable is disconnected for the first 
time, and not by the second transition. I will reload the alternate path 
with LAP messages only when the port's state changes to IB_PORT_ACTIVE. 
If the remote passive node's port has disconnected then I am expecting 
for the notice event saying that remote port transitioned to 
IB_PORT_ACTIVE. In gen1 I was using  tsIbSetInServiceNoticeHandler() for 
this. In OFED we don't have these interfaces yet.

>It seems more likely to me that the first transition does occur, since you 
>receive a MIG event on both sides, and since the alt path data is loaded by 
>you during the initial bringup of the RC QP pair(either at init->rtr, or at 
>rtr->rts). If you are receiving the MIGRATED event, the qp is already in the 
>migrated state.
>
>However, after the first migration occurs, you need to do the following:
>1.  send a LAP packet to the remote node, containing the new alt path info.
>2.  load NEW alt path information (ib_modify_qp, rts->rts), including remote 
>LID received in LAP packet.
>3.  Rearm path migration (ib_modify_qp, rts->rts)
>
>Are you certain that the above 3 steps have taken place?
>  
>
  Yes I am doing all these steps only when I get the event 
IB_PORT_ACTIVE or InServiceNotice event is received for the remote port.

>Note that 1. and 2. above are a separate phase from 3., since the IB Spec 
>allows changing the alternate path while the QP is still armed, not just when 
>it has migrated.
>
>- Jack
>  
>