net: vlan: introduce skb_vlan_eth_hdr()

Similar to skb_eth_hdr() introduced in commit 96cc4b69581d ("macvlan: do
not assume mac_header is set in macvlan_broadcast()"), let's introduce a
skb_vlan_eth_hdr() helper which can be used in TX-only code paths to get
to the VLAN header based on skb->data rather than based on the
skb_mac_header(skb).

We also consolidate the drivers that dereference skb->data to go through
this helper.

Signed-off-by: Vladimir Oltean <[e-mail]>
Reviewed-by: Eric Dumazet <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c

···
 
 		/* Skip VLAN tag if present */
 		if (ether_type == ETH_P_8021Q) {
-			struct vlan_ethhdr *vhdr =
-				(struct vlan_ethhdr *)skb->data;
+			struct vlan_ethhdr *vhdr = skb_vlan_eth_hdr(skb);
 
 			ether_type = ntohs(vhdr->h_vlan_encapsulated_proto);
 		}

drivers/net/ethernet/emulex/benet/be_main.c

···
 						  struct be_wrb_params
 						  *wrb_params)
 {
-	struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
+	struct vlan_ethhdr *veh = skb_vlan_eth_hdr(skb);
 	unsigned int eth_hdr_len;
 	struct iphdr *ip;
 

drivers/net/ethernet/hisilicon/hns3/hns3_enet.c

···
 	if (unlikely(rc < 0))
 		return rc;
 
-	vhdr = (struct vlan_ethhdr *)skb->data;
+	vhdr = skb_vlan_eth_hdr(skb);
 	vhdr->h_vlan_TCI |= cpu_to_be16((skb->priority << VLAN_PRIO_SHIFT)
 					 & VLAN_PRIO_MASK);
 

drivers/net/ethernet/intel/i40e/i40e_txrx.c

···
 			rc = skb_cow_head(skb, 0);
 			if (rc < 0)
 				return rc;
-			vhdr = (struct vlan_ethhdr *)skb->data;
+			vhdr = skb_vlan_eth_hdr(skb);
 			vhdr->h_vlan_TCI = htons(tx_flags >>
 						 I40E_TX_FLAGS_VLAN_SHIFT);
 		} else {

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

···
 
 			if (skb_cow_head(skb, 0))
 				goto out_drop;
-			vhdr = (struct vlan_ethhdr *)skb->data;
+			vhdr = skb_vlan_eth_hdr(skb);
 			vhdr->h_vlan_TCI = htons(tx_flags >>
 						 IXGBE_TX_FLAGS_VLAN_SHIFT);
 		} else {

drivers/net/ethernet/qlogic/netxen/netxen_nic_main.c

···
 
 	if (protocol == cpu_to_be16(ETH_P_8021Q)) {
 
-		vh = (struct vlan_ethhdr *)skb->data;
+		vh = skb_vlan_eth_hdr(skb);
 		protocol = vh->h_vlan_encapsulated_proto;
 		flags = FLAGS_VLAN_TAGGED;
 

drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c

···
 
 	if (adapter->flags & QLCNIC_VLAN_FILTERING) {
 		if (protocol == ETH_P_8021Q) {
-			vh = (struct vlan_ethhdr *)skb->data;
+			vh = skb_vlan_eth_hdr(skb);
 			vlan_id = ntohs(vh->h_vlan_TCI);
 		} else if (skb_vlan_tag_present(skb)) {
 			vlan_id = skb_vlan_tag_get(skb);
···
 	u32 producer = tx_ring->producer;
 
 	if (protocol == ETH_P_8021Q) {
-		vh = (struct vlan_ethhdr *)skb->data;
+		vh = skb_vlan_eth_hdr(skb);
 		flags = QLCNIC_FLAGS_VLAN_TAGGED;
 		vlan_tci = ntohs(vh->h_vlan_TCI);
 		protocol = ntohs(vh->h_vlan_encapsulated_proto);

drivers/net/ethernet/sfc/tx_tso.c

···
 	EFX_WARN_ON_ONCE_PARANOID(((struct ethhdr *)skb->data)->h_proto !=
 				  protocol);
 	if (protocol == htons(ETH_P_8021Q)) {
-		struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
+		struct vlan_ethhdr *veh = skb_vlan_eth_hdr(skb);
 
 		protocol = veh->h_vlan_encapsulated_proto;
 	}

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

···
 
 static void stmmac_rx_vlan(struct net_device *dev, struct sk_buff *skb)
 {
-	struct vlan_ethhdr *veth;
-	__be16 vlan_proto;
+	struct vlan_ethhdr *veth = skb_vlan_eth_hdr(skb);
+	__be16 vlan_proto = veth->h_vlan_proto;
 	u16 vlanid;
-
-	veth = (struct vlan_ethhdr *)skb->data;
-	vlan_proto = veth->h_vlan_proto;
 
 	if ((vlan_proto == htons(ETH_P_8021Q) &&
 	     dev->features & NETIF_F_HW_VLAN_CTAG_RX) ||

drivers/staging/gdm724x/gdm_lte.c

···
 	/* Get ethernet protocol */
 	eth = (struct ethhdr *)skb->data;
 	if (ntohs(eth->h_proto) == ETH_P_8021Q) {
-		vlan_eth = (struct vlan_ethhdr *)skb->data;
+		vlan_eth = skb_vlan_eth_hdr(skb);
 		mac_proto = ntohs(vlan_eth->h_vlan_encapsulated_proto);
 		network_data = skb->data + VLAN_ETH_HLEN;
 		nic_type |= NIC_TYPE_F_VLAN;
···
 	 * driver based on the NIC mac
 	 */
 	if (nic_type & NIC_TYPE_F_VLAN) {
-		struct vlan_ethhdr *vlan_eth = (struct vlan_ethhdr *)skb->data;
+		struct vlan_ethhdr *vlan_eth = skb_vlan_eth_hdr(skb);
 
 		nic->vlan_id = ntohs(vlan_eth->h_vlan_TCI) & VLAN_VID_MASK;
 		data_buf = skb->data + (VLAN_ETH_HLEN - ETH_HLEN);

include/linux/if_vlan.h

···
 	return (struct vlan_ethhdr *)skb_mac_header(skb);
 }
 
+/* Prefer this version in TX path, instead of
+ * skb_reset_mac_header() + vlan_eth_hdr()
+ */
+static inline struct vlan_ethhdr *skb_vlan_eth_hdr(const struct sk_buff *skb)
+{
+	return (struct vlan_ethhdr *)skb->data;
+}
+
 #define VLAN_PRIO_MASK		0xe000 /* Priority Code Point */
 #define VLAN_PRIO_SHIFT		13
 #define VLAN_CFI_MASK		0x1000 /* Canonical Format Indicator / Drop Eligible Indicator */
···
  */
 static inline int __vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
 {
-	struct vlan_ethhdr *veth = (struct vlan_ethhdr *)skb->data;
+	struct vlan_ethhdr *veth = skb_vlan_eth_hdr(skb);
 
 	if (!eth_type_vlan(veth->h_vlan_proto))
 		return -EINVAL;
···
 		if (unlikely(!pskb_may_pull(skb, VLAN_ETH_HLEN)))
 			return false;
 
-		veh = (struct vlan_ethhdr *)skb->data;
+		veh = skb_vlan_eth_hdr(skb);
 		protocol = veh->h_vlan_encapsulated_proto;
 	}
 

net/batman-adv/soft-interface.c

···
 		if (!pskb_may_pull(skb, VLAN_ETH_HLEN))
 			goto dropped;
 
-		vhdr = (struct vlan_ethhdr *)skb->data;
+		vhdr = skb_vlan_eth_hdr(skb);
 
 		/* drop batman-in-batman packets to prevent loops */
 		if (vhdr->h_vlan_encapsulated_proto != htons(ETH_P_BATMAN))