RDMA/ipoib: Print a message if only child interface is UP

When "enhanced IPoIB" is enabled for CX-5 devices it requires the parent
device to be UP, otherwise the child devices won't work.

Thus add a debug message to give admin a hint when only the child
interface is UP but parent interface is not.

Link: https://lore.kernel.org/r/20210408093215.24023-1-jinpu.wang@ionos.com
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/ulp/ipoib/ipoib_main.c

@@ -164,8 +164,13 @@ int ipoib_open(struct net_device *dev)
 			dev_change_flags(cpriv->dev, flags | IFF_UP, NULL);
 		}
 		up_read(&priv->vlan_rwsem);
-	}
+	} else if (priv->parent) {
+		struct ipoib_dev_priv *ppriv = ipoib_priv(priv->parent);
 
+		if (!test_bit(IPOIB_FLAG_ADMIN_UP, &ppriv->flags))
+			ipoib_dbg(priv, "parent device %s is not up, so child device may be not functioning.\n",
+				  ppriv->dev->name);
+	}
 	netif_start_queue(dev);
 
 	return 0;