[openib-general] CMA: port 2 loopback problems

[Sean Hefty]

Michael S. Tsirkin wrote:
> Sean, I am seeing the following problem: I have a dual-port HCA
> with IPoIB interfaces ib0 on port 1  and ib1 on port 2.
> port 1 is down and port 2 is up,
> and I try creating a connection to the loopback address 127.0.0.1.
> 
> The problem I am seeing is that I am getting RDMA_CM_EVENT_ROUTE_ERROR.
> Apparently CMA attempts address resolution through port 1, which fails.

To be clear, loopback addresses are handled separately and do not perform 
address resolution.  But they do use port 1 of the first local device in the 
CMA's device list.

The problem is that path record lookup fails.

Checking for a port that's active in cma_bind_loopback() seems like a reasonable 
  approach for now.  Is it possible to communicate between QPs on the same 
device if that device is disconnected from the fabric?

- Sean