[PATCH 1/3] iw_cm: free cm_id resources on the last deref

[swise@opengridcomputing.com (Steve Wise)]

> While I'm rambling, there is still a condition that probably needs to be
> addressed:  if the application event handler function disconnects the
> cm_id that is handling the event, the iw_cm workq thread gets stuck
> posting a IW_CM_EVENT_CLOSE to rdma_cm.  So the iw_cm workq thread is
> stuck in cm_close_handler() calling cm_id_priv->id.cm_handler() which is
> cma_iw_handler() which is blocked in cma_disable_callback() because the
> application is currently running its event handler for this cm_id.  This
> block is released when the application returns from its event handler
> function.
> 
> But maybe cma_iw_handler() should queue the event if it cannot deliver it,
> vs blocking the iw_cm workq thread?
> 

Answering myself:  queueing the event seems to be a no-go because the rdma_cm
can return non-zero to the iw_cm to indicate it should destroy the iw_cm_id.
This cannot be done correctly if the event is queued/deferred.