RDMA/ocrdma: Don't call vlan_dev_real_dev() for non-VLAN netdevs

If CONFIG_VLAN_8021Q is not set, then vlan_dev_real_dev() just goes BUG(),
so we shouldn't call it unless we're actually dealing with a VLAN netdev.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/ocrdma/ocrdma_main.c

@@ -161,7 +161,7 @@ static void ocrdma_add_default_sgid(struct ocrdma_dev *dev)
 	ocrdma_get_guid(dev, &sgid->raw[8]);
 }
 
-#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
+#if IS_ENABLED(CONFIG_VLAN_8021Q)
 static void ocrdma_add_vlan_sgids(struct ocrdma_dev *dev)
 {
 	struct net_device *netdev, *tmp;
@@ -202,14 +202,13 @@ static int ocrdma_build_sgid_tbl(struct ocrdma_dev *dev)
 	return 0;
 }
 
-#if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_VLAN_8021Q)
+#if IS_ENABLED(CONFIG_IPV6)
 
 static int ocrdma_inet6addr_event(struct notifier_block *notifier,
 				  unsigned long event, void *ptr)
 {
 	struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
-	struct net_device *event_netdev = ifa->idev->dev;
-	struct net_device *netdev = NULL;
+	struct net_device *netdev = ifa->idev->dev;
 	struct ib_event gid_event;
 	struct ocrdma_dev *dev;
 	bool found = false;
@@ -217,11 +216,12 @@ static int ocrdma_inet6addr_event(struct notifier_block *notifier,
 	bool is_vlan = false;
 	u16 vid = 0;
 
-	netdev = vlan_dev_real_dev(event_netdev);
-	if (netdev != event_netdev) {
-		is_vlan = true;
-		vid = vlan_dev_vlan_id(event_netdev);
+	is_vlan = netdev->priv_flags & IFF_802_1Q_VLAN;
+	if (is_vlan) {
+		vid = vlan_dev_vlan_id(netdev);
+		netdev = vlan_dev_real_dev(netdev);
 	}
+
 	rcu_read_lock();
 	list_for_each_entry_rcu(dev, &ocrdma_dev_list, entry) {
 		if (dev->nic_info.netdev == netdev) {