IB/mlx4: Don't register IB device for adapters with no IB ports

If the mlx4_ib driver finds an adapter that has only ethernet ports, the
current code will register an IB device with 0 ports.  Nothing useful or
sensible can be done with such a device, so just skip registering it.
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mlx4/main.c

@@ -543,14 +543,21 @@ static void *mlx4_ib_add(struct mlx4_dev *dev)
 {
 	static int mlx4_ib_version_printed;
 	struct mlx4_ib_dev *ibdev;
+	int num_ports = 0;
 	int i;
 
-
 	if (!mlx4_ib_version_printed) {
 		printk(KERN_INFO "%s", mlx4_ib_version);
 		++mlx4_ib_version_printed;
 	}
 
+	mlx4_foreach_port(i, dev, MLX4_PORT_TYPE_IB)
+		num_ports++;
+
+	/* No point in registering a device with no ports... */
+	if (num_ports == 0)
+		return NULL;
+
 	ibdev = (struct mlx4_ib_dev *) ib_alloc_device(sizeof *ibdev);
 	if (!ibdev) {
 		dev_err(&dev->pdev->dev, "Device struct alloc failed\n");
@@ -574,9 +581,7 @@ static void *mlx4_ib_add(struct mlx4_dev *dev)
 	ibdev->ib_dev.owner		= THIS_MODULE;
 	ibdev->ib_dev.node_type		= RDMA_NODE_IB_CA;
 	ibdev->ib_dev.local_dma_lkey	= dev->caps.reserved_lkey;
-	ibdev->num_ports = 0;
-	mlx4_foreach_port(i, dev, MLX4_PORT_TYPE_IB)
-		ibdev->num_ports++;
+	ibdev->num_ports		= num_ports;
 	ibdev->ib_dev.phys_port_cnt     = ibdev->num_ports;
 	ibdev->ib_dev.num_comp_vectors	= dev->caps.num_comp_vectors;
 	ibdev->ib_dev.dma_device	= &dev->pdev->dev;