From: Julian Wiedmann <jwi@linux.ibm.com>
Subject: s390/qeth: robustify qeth_get_ip_version()
Patch-mainline: v4.16-rc1
Git-commit: 19e36da61a90fe95116634f66196cc9b2e61b368
References: FATE#326350, LTC#169511, bsc#1113509

Summary:     qeth: performance improvements
Description: This adds recent functional and performance improvements for the
             qeth network driver.
             Primarily this brings Scatter-Gather support for HiperSockets,
             reduced CPU consumption in the L3 IPv4 transmit path for OSA,
             improved Promiscuous Mode performance due to IFF_UNICAST_FLT,
             support for Scatter-Gather on z/VM virtual NICs, and
             support for delayed GRO flushing.

             For sanity & stability reasons, this effectively constitutes a
             backport of the qeth device driver from 4.19 mainline.
             

Upstream-Description:

             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@linux.vnet.ibm.com>
             Signed-off-by: David S. Miller <davem@davemloft.net>

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

--- a/drivers/s390/net/qeth_core.h
+++ b/drivers/s390/net/qeth_core.h
@@ -861,14 +861,16 @@ 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;