vlan: fix bond/team enslave of vlan challenged slave/port

In vlan_uses_dev() check for number of vlan devs rather than existence
of vlan_info. The reason is that vlan id 0 is there without appropriate
vlan dev on it by default which prevented from enslaving vlan challenged
dev.

Reported-by: Jon Stanley <jstanley@rmrf.net>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 9 insertions, 2 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index b721902bb6b4..b2530b002125 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1519,7 +1519,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
         /* no need to lock since we're protected by rtnl_lock */
         if (slave_dev->features & NETIF_F_VLAN_CHALLENGED) {
                 pr_debug("%s: NETIF_F_VLAN_CHALLENGED\n", slave_dev->name);
-                if (bond_vlan_used(bond)) {
+                if (vlan_uses_dev(bond_dev)) {
                         pr_err("%s: Error: cannot enslave VLAN challenged slave %s on VLAN enabled bond %s\n",
                                bond_dev->name, slave_dev->name, bond_dev->name);
                         return -EPERM;
diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index fbbf1fa00940..65e06abe023f 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -366,6 +366,13 @@ EXPORT_SYMBOL(vlan_vids_del_by_dev);
 
 bool vlan_uses_dev(const struct net_device *dev)
 {
-        return rtnl_dereference(dev->vlan_info) ? true : false;
+        struct vlan_info *vlan_info;
+
+        ASSERT_RTNL();
+
+        vlan_info = rtnl_dereference(dev->vlan_info);
+        if (!vlan_info)
+                return false;
+        return vlan_info->grp.nr_vlan_devs ? true : false;
 }
 EXPORT_SYMBOL(vlan_uses_dev);