IB/ipoib: Grab rtnl lock on heavy flush when calling ndo_open/stop

When ndo_open and ndo_stop are called RTNL lock should be held.
In this specific case ipoib_ib_dev_open calls the offloaded ndo_open
which re-sets the number of TX queue assuming RTNL lock is held.
Since RTNL lock is not held, RTNL assert will fail.
Signed-off-by: Alex Vesker <valex@mellanox.com>

drivers/infiniband/ulp/ipoib/ipoib_ib.c

@@ -1203,10 +1203,15 @@ static void __ipoib_ib_dev_flush(struct ipoib_dev_priv *priv,
 		ipoib_ib_dev_down(dev);
 
 	if (level == IPOIB_FLUSH_HEAVY) {
+		rtnl_lock();
 		if (test_bit(IPOIB_FLAG_INITIALIZED, &priv->flags))
 			ipoib_ib_dev_stop(dev);
-		if (ipoib_ib_dev_open(dev) != 0)
+
+		result = ipoib_ib_dev_open(dev);
+		rtnl_unlock();
+		if (result)
 			return;
+
 		if (netif_queue_stopped(dev))
 			netif_start_queue(dev);
 	}