[B.A.T.M.A.N.] [PATCHv6 1/2] batman-adv: use vlan_/eth_hdr() instead of skb->data in interface_tx path

["Linus Lüssing" <linus.luessing@web.de>]

Our .ndo_start_xmit handler (batadv_interface_tx()) can rely on having
the skb mac header pointer set correctly since the following commit
present in kernels >= 3.9:

"net: reset mac header in dev_start_xmit()" (6d1ccff627)

Therefore we can safely use eth_hdr() and vlan_eth_hdr() instead of
skb->data now, which spares us some ugly type casts.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
 bridge_loop_avoidance.c |    2 +-
 compat.h                |   11 +++++++++++
 gateway_client.c        |    6 +++---
 send.c                  |    2 +-
 soft-interface.c        |    8 ++++----
 5 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/bridge_loop_avoidance.c b/bridge_loop_avoidance.c
index 5c0eda4..407299a 100644
--- a/bridge_loop_avoidance.c
+++ b/bridge_loop_avoidance.c
@@ -872,7 +872,7 @@ static int batadv_bla_process_claim(struct batadv_priv *bat_priv,
 	proto = ethhdr->h_proto;
 	headlen = ETH_HLEN;
 	if (vid & BATADV_VLAN_HAS_TAG) {
-		vhdr = (struct vlan_ethhdr *)ethhdr;
+		vhdr = vlan_eth_hdr(skb);
 		proto = vhdr->h_vlan_encapsulated_proto;
 		headlen += VLAN_HLEN;
 	}
diff --git a/compat.h b/compat.h
index 57c9d96..9692ed2 100644
--- a/compat.h
+++ b/compat.h
@@ -302,6 +302,17 @@ static int batadv_interface_set_mac_addr(struct net_device *dev, void *p) \
 }\
 static int __batadv_interface_set_mac_addr(x, y)
 
+#define batadv_interface_tx(x, y) \
+__batadv_interface_tx(struct sk_buff *skb, struct net_device *soft_iface); \
+static int batadv_interface_tx(struct sk_buff *skb, \
+			       struct net_device *soft_iface) \
+{ \
+	skb_reset_mac_header(skb); \
+	return __batadv_interface_tx(skb, soft_iface); \
+} \
+static int __batadv_interface_tx(struct sk_buff *skb, \
+				 struct net_device *soft_iface)
+
 #define netdev_master_upper_dev_link netdev_set_master
 #define netdev_upper_dev_unlink(slave, master) netdev_set_master(slave, NULL)
 #define netdev_master_upper_dev_get(dev) \
diff --git a/gateway_client.c b/gateway_client.c
index 55cf226..ab0c97e 100644
--- a/gateway_client.c
+++ b/gateway_client.c
@@ -680,7 +680,7 @@ batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
 	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 		return BATADV_DHCP_NO;
 
-	ethhdr = (struct ethhdr *)skb->data;
+	ethhdr = eth_hdr(skb);
 	proto = ethhdr->h_proto;
 	*header_len += ETH_HLEN;
 
@@ -689,7 +689,7 @@ batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
 		if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 			return BATADV_DHCP_NO;
 
-		vhdr = (struct vlan_ethhdr *)skb->data;
+		vhdr = vlan_eth_hdr(skb);
 		proto = vhdr->h_vlan_encapsulated_proto;
 		*header_len += VLAN_HLEN;
 	}
@@ -728,7 +728,7 @@ batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
 		return BATADV_DHCP_NO;
 
 	/* skb->data might have been reallocated by pskb_may_pull() */
-	ethhdr = (struct ethhdr *)skb->data;
+	ethhdr = eth_hdr(skb);
 	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
 		ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
 
diff --git a/send.c b/send.c
index 579f5f0..3299b0e 100644
--- a/send.c
+++ b/send.c
@@ -254,7 +254,7 @@ static int batadv_send_skb_unicast(struct batadv_priv *bat_priv,
 				   struct batadv_orig_node *orig_node,
 				   unsigned short vid)
 {
-	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
+	struct ethhdr *ethhdr = eth_hdr(skb);
 	struct batadv_unicast_packet *unicast_packet;
 	int ret = NET_XMIT_DROP;
 
diff --git a/soft-interface.c b/soft-interface.c
index f82c267..c4392fc 100644
--- a/soft-interface.c
+++ b/soft-interface.c
@@ -176,11 +176,11 @@ static int batadv_interface_tx(struct sk_buff *skb,
 
 	soft_iface->trans_start = jiffies;
 	vid = batadv_get_vid(skb, 0);
-	ethhdr = (struct ethhdr *)skb->data;
+	ethhdr = eth_hdr(skb);
 
 	switch (ntohs(ethhdr->h_proto)) {
 	case ETH_P_8021Q:
-		vhdr = (struct vlan_ethhdr *)skb->data;
+		vhdr = vlan_eth_hdr(skb);
 
 		if (vhdr->h_vlan_encapsulated_proto != ethertype)
 			break;
@@ -194,7 +194,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
 		goto dropped;
 
 	/* skb->data might have been reallocated by batadv_bla_tx() */
-	ethhdr = (struct ethhdr *)skb->data;
+	ethhdr = eth_hdr(skb);
 
 	/* Register the client MAC in the transtable */
 	if (!is_multicast_ether_addr(ethhdr->h_source)) {
@@ -230,7 +230,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
 		/* skb->data may have been modified by
 		 * batadv_gw_dhcp_recipient_get()
 		 */
-		ethhdr = (struct ethhdr *)skb->data;
+		ethhdr = eth_hdr(skb);
 		/* if gw_mode is on, broadcast any non-DHCP message.
 		 * All the DHCP packets are going to be sent as unicast
 		 */
-- 
1.7.10.4