netdev - [PATCH net-next 09/15] s390/qeth: robustify qeth_get_ip

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Date:   Wed, 20 Dec 2017 20:11:03 +0100
From:   Julian Wiedmann <jwi@...ux.vnet.ibm.com>
To:     David Miller <davem@...emloft.net>
Cc:     <netdev@...r.kernel.org>, <linux-s390@...r.kernel.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Stefan Raspl <raspl@...ux.vnet.ibm.com>,
        Ursula Braun <ubraun@...ux.vnet.ibm.com>,
        Julian Wiedmann <jwi@...ux.vnet.ibm.com>
Subject: [PATCH net-next 09/15] s390/qeth: robustify qeth_get_ip_version()

Instead of assuming that skb->data points to the Ethernet header, use
the right helper and struct to access the Ethertype field.

Signed-off-by: Julian Wiedmann <jwi@...ux.vnet.ibm.com>
---
 drivers/s390/net/qeth_core.h | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h
index f5ee62c98011..af9d1efd2e78 100644
--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -847,14 +847,16 @@ static inline int qeth_get_micros(void)
 
 static inline int qeth_get_ip_version(struct sk_buff *skb)
 {
-	__be16 *p = &((struct ethhdr *)skb->data)->h_proto;
+	struct vlan_ethhdr *veth = vlan_eth_hdr(skb);
+	__be16 prot = veth->h_vlan_proto;
 
-	if (be16_to_cpu(*p) == ETH_P_8021Q)
-		p += 2;
-	switch (be16_to_cpu(*p)) {
-	case ETH_P_IPV6:
+	if (prot == htons(ETH_P_8021Q))
+		prot = veth->h_vlan_encapsulated_proto;
+
+	switch (prot) {
+	case htons(ETH_P_IPV6):
 		return 6;
-	case ETH_P_IP:
+	case htons(ETH_P_IP):
 		return 4;
 	default:
 		return 0;
-- 
2.13.5