net: mvpp2: Extract the correct ethtype from the skb for tx csum offload

When offloading the L3 and L4 csum computation on TX, we need to extract
the l3_proto from the ethtype, independently of the presence of a vlan
tag.

The actual driver uses skb->protocol as-is, resulting in packets with
the wrong L4 checksum being sent when there's a vlan tag in the packet
header and checksum offloading is enabled.

This commit makes use of vlan_protocol_get() to get the correct ethtype
regardless the presence of a vlan tag.

Fixes: 3f518509dedc ("ethernet: Add new driver for Marvell Armada 375 network unit")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index 38cc01beea79..a74002b43b51 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -1725,7 +1725,7 @@ static void mvpp2_txq_desc_put(struct mvpp2_tx_queue *txq)
 }
 
 /* Set Tx descriptors fields relevant for CSUM calculation */
-static u32 mvpp2_txq_desc_csum(int l3_offs, int l3_proto,
+static u32 mvpp2_txq_desc_csum(int l3_offs, __be16 l3_proto,
                                int ip_hdr_len, int l4_proto)
 {
         u32 command;
@@ -2600,14 +2600,15 @@ static u32 mvpp2_skb_tx_csum(struct mvpp2_port *port, struct sk_buff *skb)
         if (skb->ip_summed == CHECKSUM_PARTIAL) {
                 int ip_hdr_len = 0;
                 u8 l4_proto;
+                __be16 l3_proto = vlan_get_protocol(skb);
 
-                if (skb->protocol == htons(ETH_P_IP)) {
+                if (l3_proto == htons(ETH_P_IP)) {
                         struct iphdr *ip4h = ip_hdr(skb);
 
                         /* Calculate IPv4 checksum and L4 checksum */
                         ip_hdr_len = ip4h->ihl;
                         l4_proto = ip4h->protocol;
-                } else if (skb->protocol == htons(ETH_P_IPV6)) {
+                } else if (l3_proto == htons(ETH_P_IPV6)) {
                         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 
                         /* Read l4_protocol from one of IPv6 extra headers */
@@ -2619,7 +2620,7 @@ static u32 mvpp2_skb_tx_csum(struct mvpp2_port *port, struct sk_buff *skb)
                 }
 
                 return mvpp2_txq_desc_csum(skb_network_offset(skb),
-                                skb->protocol, ip_hdr_len, l4_proto);
+                                           l3_proto, ip_hdr_len, l4_proto);
         }
 
         return MVPP2_TXD_L4_CSUM_NOT | MVPP2_TXD_IP_CSUM_DISABLE;