dpcreconciler/linuxitems/adapter.go: set MAC and interface rename whi…

…le interface is DOWN

On attempt to set MAC address or rename interface which is UP
host returns `Device or resource busy`. Patch fixes the error
by changing the order: first set MAC and rename interface,
then bring interface UP.

Patch fixes inability to use host interface, the problem was
reproduced on RPI4 board. Presumably any device should be
affected.

Signed-off-by: Roman Penyaev <[email protected]>
Fixes: 7a6981b ("Add support for switch network instance with multiple ports")

pkg/pillar/dpcreconciler/linuxitems/adapter.go

@@ -131,14 +131,14 @@ func (c *AdapterConfigurator) Create(ctx context.Context, item depgraph.Item) er
 		// Managed by the wwan microservice, nothing to do here.
 		return nil
 	}
-	// Make sure that the interface is UP.
-	if err := netlink.LinkSetUp(link); err != nil {
-		err = fmt.Errorf("netlink.LinkSetUp(%s) failed: %v",
-			adapter.IfName, err)
-		c.Log.Error(err)
-		return err
-	}
 	if !c.isAdapterBridgedByNIM(adapter) {
+		// Make sure that the interface is UP.
+		if err := netlink.LinkSetUp(link); err != nil {
+			err = fmt.Errorf("netlink.LinkSetUp(%s) failed: %v",
+				adapter.IfName, err)
+			c.Log.Error(err)
+			return err
+		}
 		// Do not proceed with bridging the adapter, just set the MTU.
 		return c.setAdapterMTU(adapter, link)
 	}
@@ -195,12 +195,21 @@ func (c *AdapterConfigurator) Create(ctx context.Context, item depgraph.Item) er
 		c.Log.Error(err)
 		return err
 	}
+	// Make sure that corresponding bridge and interface are UP right
+	// after MAC address assignment and interface rename. Order matters,
+	// otherwise host returns `Device or resource busy`.
 	if err := netlink.LinkSetUp(bridge); err != nil {
 		err = fmt.Errorf("netlink.LinkSetUp(%s) failed: %v",
 			adapter.IfName, err)
 		c.Log.Error(err)
 		return err
 	}
+	if err := netlink.LinkSetUp(kernLink); err != nil {
+		err = fmt.Errorf("netlink.LinkSetUp(%s) failed: %v",
+			adapter.IfName, err)
+		c.Log.Error(err)
+		return err
+	}
 	return nil
 }