ipoib_warn(priv, "enabling connected mode "
                           "will cause multicast packet drops\n");
 
+               rtnl_lock();
                dev->features &= ~(NETIF_F_IP_CSUM | NETIF_F_SG | NETIF_F_TSO);
+               rtnl_unlock();
                priv->tx_wr.send_flags &= ~IB_SEND_IP_CSUM;
 
                ipoib_flush_paths(dev);
 
        if (!strcmp(buf, "datagram\n")) {
                clear_bit(IPOIB_FLAG_ADMIN_CM, &priv->flags);
-               dev->mtu = min(priv->mcast_mtu, dev->mtu);
-               ipoib_flush_paths(dev);
 
+               rtnl_lock();
                if (test_bit(IPOIB_FLAG_CSUM, &priv->flags)) {
                        dev->features |= NETIF_F_IP_CSUM | NETIF_F_SG;
                        if (priv->hca_caps & IB_DEVICE_UD_TSO)
                                dev->features |= NETIF_F_TSO;
                }
+               dev->mtu = min(priv->mcast_mtu, dev->mtu);
+               rtnl_unlock();
+               ipoib_flush_paths(dev);
 
                return count;
        }
 
 
        priv->mcast_mtu = IPOIB_UD_MTU(ib_mtu_enum_to_int(priv->broadcast->mcmember.mtu));
 
-       if (!ipoib_cm_admin_enabled(dev))
+       if (!ipoib_cm_admin_enabled(dev)) {
+               rtnl_lock();
                dev->mtu = min(priv->mcast_mtu, priv->admin_mtu);
+               rtnl_unlock();
+       }
 
        ipoib_dbg_mcast(priv, "successfully joined all multicast groups\n");