<<<snip>>>

+ *	l3mdev_master_ifindex - get index of L3 master device
+ *	@dev: targeted interface
+ */
+
+int l3mdev_master_ifindex_rcu(struct net_device *dev)
+{
+	int ifindex = 0;
+
+	if (!dev)
+		return 0;
+
+	if (netif_is_l3_master(dev)) {
+		ifindex = dev->ifindex;
+

^^
Extra empty line.

+	} else if (dev->flags & IFF_SLAVE) {
+		struct net_device *master;
+
+		master = netdev_master_upper_dev_get_rcu(dev);
+		if (netif_is_l3_master(master))

^^
maybe check if master is non-null, otherwise this imposes a new
restriction on the ordering of iff_slave / master_upper setting,
also a very old driver that uses iff_slave/master doesn't set the
master_upper, but only the flag (eql).
Actually, is this bisectable ? I see netif_is_l3_master() being
introduced in the next patch, so I don't think you can compile
this one.

+			ifindex = master->ifindex;
+	}
+
+	return ifindex;
+}
+
+/**
+ *	l3mdev_fib_table - get FIB table id associated with an L3
+ *                             master interface
+ *	@dev: targeted interface
+ */
+
+u32 l3mdev_fib_table_rcu(const struct net_device *dev)
+{
+	u32 tb_id = 0;
+
+	if (!dev)
+		return 0;
+
+	if (netif_is_l3_master(dev)) {
+		if (dev->l3mdev_ops->l3mdev_fib_table)
+			tb_id = dev->l3mdev_ops->l3mdev_fib_table(dev);
+

^^
Extra empty line.

+	} else if (dev->flags & IFF_SLAVE) {
+		/* TO-DO: remove the need for typecast.
+		 * Users of netdev_master_upper_dev_get_rcu need non-const,
+		 * but current inet_*type functions take a const
+		 */
+		struct net_device *_dev = (struct net_device *) dev;
+		const struct net_device *master;
+
+		master = netdev_master_upper_dev_get_rcu(_dev);
+		if (!master)
+			return 0;
+
+		if (netif_is_l3_master(master) &&
+		    master->l3mdev_ops->l3mdev_fib_table)
+			tb_id = master->l3mdev_ops->l3mdev_fib_table(master);
+	}
+
+	return tb_id;
+}
+
+u32 l3mdev_fib_table_by_index(struct net *net, int ifindex)
+{
+	struct net_device *dev;
+	u32 tb_id = 0;
+
+	if (!ifindex)
+		return 0;
+
+	rcu_read_lock();
+
+	dev = dev_get_by_index_rcu(net, ifindex);
+	if (dev)
+		tb_id = l3mdev_fib_table_rcu(dev);
+
+	rcu_read_unlock();
+
+	return tb_id;
+}