Add migrate_send_rp_message to send a message from destination to source along the return path.
(It uses a mutex to let it be called from multiple threads)
Add migrate_send_rp_shut to send a 'shut' message to indicate
the destination is finished with the RP.
Add migrate_send_rp_ack to send a 'PONG' message in response to a PING
Use it in the MSG_RP_PING handler
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
6decec9311