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From:   Yan Markman <ymarkman@marvell.com>
To:     Maxime Chevallier <maxime.chevallier@bootlin.com>,
        "davem@davemloft.net" <davem@davemloft.net>
CC:     "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Antoine Tenart <antoine.tenart@bootlin.com>,
        "thomas.petazzoni@bootlin.com" <thomas.petazzoni@bootlin.com>,
        "gregory.clement@bootlin.com" <gregory.clement@bootlin.com>,
        "miquel.raynal@bootlin.com" <miquel.raynal@bootlin.com>,
        Nadav Haklai <nadavh@marvell.com>,
        "Stefan Chulski" <stefanc@marvell.com>,
        "mw@semihalf.com" <mw@semihalf.com>
Subject: RE: [EXT] [PATCH net] net: mvpp2: Extract the correct ethtype from
 the skb for tx csum offload
Thread-Topic: [EXT] [PATCH net] net: mvpp2: Extract the correct ethtype from
 the skb for tx csum offload
Thread-Index: AQHUW7i7bKe3wJSXT06HrXe4bVthZaUOumRg
Date:   Thu, 4 Oct 2018 08:08:24 +0000
Message-ID: <763e186250f44f9ab7208478442ce1a4@IL-EXCH02.marvell.com>
References: <20181004080308.7687-1-maxime.chevallier@bootlin.com>
In-Reply-To: <20181004080308.7687-1-maxime.chevallier@bootlin.com>
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I'm not sure that kind of ntohs() using is good for the Performance.=20
htons(ETH_P_IP) is CONSTANT swapped Big/LittleEndian by COMPILER whilst the=
=20
ntohs(vlan_get_protocol(skb)) is run-time short/byte-swap for every packet.

Yan Markman

-----Original Message-----
From: Maxime Chevallier [mailto:maxime.chevallier@bootlin.com]=20
Sent: Thursday, October 04, 2018 11:03 AM
To: davem@davemloft.net
Cc: Maxime Chevallier <maxime.chevallier@bootlin.com>; netdev@vger.kernel.o=
rg; linux-kernel@vger.kernel.org; Antoine Tenart <antoine.tenart@bootlin.co=
m>; thomas.petazzoni@bootlin.com; gregory.clement@bootlin.com; miquel.rayna=
l@bootlin.com; Nadav Haklai <nadavh@marvell.com>; Stefan Chulski <stefanc@m=
arvell.com>; Yan Markman <ymarkman@marvell.com>; mw@semihalf.com
Subject: [EXT] [PATCH net] net: mvpp2: Extract the correct ethtype from the=
 skb for tx csum offload

External Email

----------------------------------------------------------------------
When offloading the L3 and L4 csum computation on TX, we need to extract th=
e 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 w=
rong L4 checksum being sent when there's a vlan tag in the packet header an=
d checksum offloading is enabled.

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

Fixes: 3f51850 ("ethernet: Add new driver for Marvell Armada 375 network un=
it")
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 9 +++++----
 1 file 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..4bd5b251e3c7 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -1737,7 +1737,7 @@ static u32 mvpp2_txq_desc_csum(int l3_offs, int l3_pr=
oto,
 	command |=3D (ip_hdr_len << MVPP2_TXD_IP_HLEN_SHIFT);
 	command |=3D MVPP2_TXD_IP_CSUM_DISABLE;
=20
-	if (l3_proto =3D=3D htons(ETH_P_IP)) {
+	if (l3_proto =3D=3D ETH_P_IP) {
 		command &=3D ~MVPP2_TXD_IP_CSUM_DISABLE;	/* enable IPv4 csum */
 		command &=3D ~MVPP2_TXD_L3_IP6;		/* enable IPv4 */
 	} else {
@@ -2600,14 +2600,15 @@ static u32 mvpp2_skb_tx_csum(struct mvpp2_port *por=
t, struct sk_buff *skb)
 	if (skb->ip_summed =3D=3D CHECKSUM_PARTIAL) {
 		int ip_hdr_len =3D 0;
 		u8 l4_proto;
+		int l3_proto =3D ntohs(vlan_get_protocol(skb));
=20
-		if (skb->protocol =3D=3D htons(ETH_P_IP)) {
+		if (l3_proto =3D=3D ETH_P_IP) {
 			struct iphdr *ip4h =3D ip_hdr(skb);
=20
 			/* Calculate IPv4 checksum and L4 checksum */
 			ip_hdr_len =3D ip4h->ihl;
 			l4_proto =3D ip4h->protocol;
-		} else if (skb->protocol =3D=3D htons(ETH_P_IPV6)) {
+		} else if (l3_proto =3D=3D ETH_P_IPV6) {
 			struct ipv6hdr *ip6h =3D ipv6_hdr(skb);
=20
 			/* 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)
 		}
=20
 		return mvpp2_txq_desc_csum(skb_network_offset(skb),
-				skb->protocol, ip_hdr_len, l4_proto);
+					   l3_proto, ip_hdr_len, l4_proto);
 	}
=20
 	return MVPP2_TXD_L4_CSUM_NOT | MVPP2_TXD_IP_CSUM_DISABLE;
--
2.11.0