+
+static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
+{
+ if (skb_cow(skb, skb_headroom(skb)) < 0) {
+ kfree_skb(skb);
+ return NULL;
+ }
+
+ memmove(skb->data - ETH_HLEN, skb->data - VLAN_ETH_HLEN, 2 * ETH_ALEN);
+ skb->mac_header += VLAN_HLEN;
+ return skb;
+}
+
+struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
+{
+ struct vlan_hdr *vhdr;
+ u16 vlan_tci;
+
+ if (unlikely(vlan_tx_tag_present(skb))) {
+ /* vlan_tci is already set-up so leave this for another time */
+ return skb;
+ }
+
+ skb = skb_share_check(skb, GFP_ATOMIC);
+ if (unlikely(!skb))
+ goto err_free;
+
+ if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
+ goto err_free;
+
+ vhdr = (struct vlan_hdr *)skb->data;
+ vlan_tci = ntohs(vhdr->h_vlan_TCI);
+ __vlan_hwaccel_put_tag(skb, skb->protocol, vlan_tci);
+
+ skb_pull_rcsum(skb, VLAN_HLEN);
+ vlan_set_encap_proto(skb, vhdr);
+
+ skb = skb_reorder_vlan_header(skb);
+ if (unlikely(!skb))
+ goto err_free;
+
+ skb_reset_network_header(skb);
+ skb_reset_transport_header(skb);
+ skb_reset_mac_len(skb);
+
+ return skb;
+
+err_free:
+ kfree_skb(skb);
+ return NULL;
+}
+EXPORT_SYMBOL(skb_vlan_untag);