IPoIB: Use dev_set_mtu() to change mtu

When the driver sets the MTU of the net device outside of its
change_mtu method, it should make use of dev_set_mtu() instead of
directly setting the mtu field of struct netdevice.  Otherwise
functions registered to be called upon MTU change will not get called
(this is done through call_netdevice_notifiers() in dev_set_mtu()).
Signed-off-by: NEli Cohen <eli@mellanox.co.il>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

drivers/infiniband/ulp/ipoib/ipoib_cm.c

@@ -1458,7 +1458,7 @@ static ssize_t set_mode(struct device *d, struct device_attribute *attr,
 			if (priv->hca_caps & IB_DEVICE_UD_TSO)
 				dev->features |= NETIF_F_TSO;
 		}
-		dev->mtu = min(priv->mcast_mtu, dev->mtu);
+		dev_set_mtu(dev, min(priv->mcast_mtu, dev->mtu));
 		rtnl_unlock();
 		ipoib_flush_paths(dev);
 

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

@@ -577,7 +577,7 @@ void ipoib_mcast_join_task(struct work_struct *work)
 
 	if (!ipoib_cm_admin_enabled(dev)) {
 		rtnl_lock();
-		dev->mtu = min(priv->mcast_mtu, priv->admin_mtu);
+		dev_set_mtu(dev, min(priv->mcast_mtu, priv->admin_mtu));
 		rtnl_unlock();
 	}