RDMA/cma: Queue IB CM MRAs to avoid unnecessary remote retries

Automatically queue MRA message to decrease the number of retries sent
by the remote side during connection establishment.  This also has the
effect of increasing the overall connection timeout without using a
longer retry time in the case of dropped packets.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/cma.c

@@ -52,6 +52,7 @@ MODULE_LICENSE("Dual BSD/GPL");
 
 #define CMA_CM_RESPONSE_TIMEOUT 20
 #define CMA_MAX_CM_RETRIES 15
+#define CMA_CM_MRA_SETTING (IB_CM_MRA_FLAG_DELAY | 24)
 
 static void cma_add_one(struct ib_device *device);
 static void cma_remove_one(struct ib_device *device);
@@ -1090,6 +1091,7 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event)
 		event.param.ud.private_data_len =
 				IB_CM_SIDR_REQ_PRIVATE_DATA_SIZE - offset;
 	} else {
+		ib_send_cm_mra(cm_id, CMA_CM_MRA_SETTING, NULL, 0);
 		conn_id = cma_new_conn_id(&listen_id->id, ib_event);
 		cma_set_req_event_data(&event, &ib_event->param.req_rcvd,
 				       ib_event->private_data, offset);