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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Maxime Chevallier <maxime.chevallier@bootlin.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.18 013/135] net: mvpp2: Extract the correct ethtype from the skb for tx csum offload
Date:   Tue, 16 Oct 2018 19:04:03 +0200
Message-Id: <20181016170516.328437839@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Maxime Chevallier <maxime.chevallier@bootlin.com>

[ Upstream commit 35f3625c21852ad839f20c91c7d81c4c1101e207 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- 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 mv
 }
 
 /* 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 mvpp
 	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 mvpp
 		}
 
 		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;