2 files changed, 24 insertions, 14 deletions

diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index 79504b22a932..edd55af7ebd6 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -93,7 +93,7 @@ static inline struct net_device *vlan_group_get_device(struct vlan_group *vg,
 {
         struct net_device **array;
         array = vg->vlan_devices_arrays[vlan_id / VLAN_GROUP_ARRAY_PART_LEN];
-        return array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN];
+        return array ? array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN] : NULL;
 }
 
 static inline void vlan_group_set_device(struct vlan_group *vg,
diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index c35dc230365c..694be86e4490 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -106,29 +106,35 @@ static void vlan_group_free(struct vlan_group *grp)
 static struct vlan_group *vlan_group_alloc(int ifindex)
 {
         struct vlan_group *grp;
-        unsigned int size;
-        unsigned int i;
 
         grp = kzalloc(sizeof(struct vlan_group), GFP_KERNEL);
         if (!grp)
                 return NULL;
 
-        size = sizeof(struct net_device *) * VLAN_GROUP_ARRAY_PART_LEN;
-
-        for (i = 0; i < VLAN_GROUP_ARRAY_SPLIT_PARTS; i++) {
-                grp->vlan_devices_arrays[i] = kzalloc(size, GFP_KERNEL);
-                if (!grp->vlan_devices_arrays[i])
-                        goto err;
-        }
-
         grp->real_dev_ifindex = ifindex;
         hlist_add_head_rcu(&grp->hlist,
                            &vlan_group_hash[vlan_grp_hashfn(ifindex)]);
         return grp;
+}
 
-err:
-        vlan_group_free(grp);
-        return NULL;
+static int vlan_group_prealloc_vid(struct vlan_group *vg, int vid)
+{
+        struct net_device **array;
+        unsigned int size;
+
+        ASSERT_RTNL();
+
+        array = vg->vlan_devices_arrays[vid / VLAN_GROUP_ARRAY_PART_LEN];
+        if (array != NULL)
+                return 0;
+
+        size = sizeof(struct net_device *) * VLAN_GROUP_ARRAY_PART_LEN;
+        array = kzalloc(size, GFP_KERNEL);
+        if (array == NULL)
+                return -ENOBUFS;
+
+        vg->vlan_devices_arrays[vid / VLAN_GROUP_ARRAY_PART_LEN] = array;
+        return 0;
 }
 
 static void vlan_rcu_free(struct rcu_head *rcu)
@@ -247,6 +253,10 @@ int register_vlan_dev(struct net_device *dev)
                         return -ENOBUFS;
         }
 
+        err = vlan_group_prealloc_vid(grp, vlan_id);
+        if (err < 0)
+                goto out_free_group;
+
         err = register_netdevice(dev);
         if (err < 0)
                 goto out_free_group;