IB/mlx5: Support IB device's callback for getting its netdev

For Eth ports only:
Maintain a net device pointer in mlx5_ib_device and update it
upon NETDEV_REGISTER and NETDEV_UNREGISTER events if the
net-device and IB device have the same PCI parent device.
Implement the get_netdev callback to return this net device.

Signed-off-by: Achiad Shochat <achiad@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 6333472..1eaa611 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -407,9 +407,19 @@
 	struct ib_srq	*s1;
 };
 
+struct mlx5_roce {
+	/* Protect mlx5_ib_get_netdev from invoking dev_hold() with a NULL
+	 * netdev pointer
+	 */
+	rwlock_t		netdev_lock;
+	struct net_device	*netdev;
+	struct notifier_block	nb;
+};
+
 struct mlx5_ib_dev {
 	struct ib_device		ib_dev;
 	struct mlx5_core_dev		*mdev;
+	struct mlx5_roce		roce;
 	MLX5_DECLARE_DOORBELL_LOCK(uar_lock);
 	int				num_ports;
 	/* serialize update of capability mask