[PATCH 3.2 146/152] enic: fix rx skb checksum

[Ben Hutchings]

3.2.67-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Govindarajulu Varadarajan <_govind@xxxxxxx>

[ Upstream commit 17e96834fd35997ca7cdfbf15413bcd5a36ad448 ]

Hardware always provides compliment of IP pseudo checksum. Stack expects
whole packet checksum without pseudo checksum if CHECKSUM_COMPLETE is set.

This causes checksum error in nf & ovs.

kernel: qg-19546f09-f2: hw csum failure
kernel: CPU: 9 PID: 0 Comm: swapper/9 Tainted: GF          O--------------   3.10.0-123.8.1.el7.x86_64 #1
kernel: Hardware name: Cisco Systems Inc UCSB-B200-M3/UCSB-B200-M3, BIOS B200M3.2.2.3.0.080820141339 08/08/2014
kernel: ffff881218f40000 df68243feb35e3a8 ffff881237a43ab8 ffffffff815e237b
kernel: ffff881237a43ad0 ffffffff814cd4ca ffff8829ec71eb00 ffff881237a43af0
kernel: ffffffff814c6232 0000000000000286 ffff8829ec71eb00 ffff881237a43b00
kernel: Call Trace:
kernel: <IRQ>  [<ffffffff815e237b>] dump_stack+0x19/0x1b
kernel: [<ffffffff814cd4ca>] netdev_rx_csum_fault+0x3a/0x40
kernel: [<ffffffff814c6232>] __skb_checksum_complete_head+0x62/0x70
kernel: [<ffffffff814c6251>] __skb_checksum_complete+0x11/0x20
kernel: [<ffffffff8155a20c>] nf_ip_checksum+0xcc/0x100
kernel: [<ffffffffa049edc7>] icmp_error+0x1f7/0x35c [nf_conntrack_ipv4]
kernel: [<ffffffff814cf419>] ? netif_rx+0xb9/0x1d0
kernel: [<ffffffffa040eb7b>] ? internal_dev_recv+0xdb/0x130 [openvswitch]
kernel: [<ffffffffa04c8330>] nf_conntrack_in+0xf0/0xa80 [nf_conntrack]
kernel: [<ffffffff81509380>] ? inet_del_offload+0x40/0x40
kernel: [<ffffffffa049e302>] ipv4_conntrack_in+0x22/0x30 [nf_conntrack_ipv4]
kernel: [<ffffffff815005ca>] nf_iterate+0xaa/0xc0
kernel: [<ffffffff81509380>] ? inet_del_offload+0x40/0x40
kernel: [<ffffffff81500664>] nf_hook_slow+0x84/0x140
kernel: [<ffffffff81509380>] ? inet_del_offload+0x40/0x40
kernel: [<ffffffff81509dd4>] ip_rcv+0x344/0x380

Hardware verifies IP & tcp/udp header checksum but does not provide payload
checksum, use CHECKSUM_UNNECESSARY. Set it only if its valid IP tcp/udp packet.

Cc: Jiri Benc <jbenc@xxxxxxxxxx>
Cc: Stefan Assmann <sassmann@xxxxxxxxxx>
Reported-by: Sunil Choudhary <schoudha@xxxxxxxxxx>
Signed-off-by: Govindarajulu Varadarajan <_govind@xxxxxxx>
Reviewed-by: Jiri Benc <jbenc@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/cisco/enic/enic_main.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/net/ethernet/cisco/enic/enic_main.c
+++ b/drivers/net/ethernet/cisco/enic/enic_main.c
@@ -1272,10 +1272,14 @@ static void enic_rq_indicate_buf(struct
 		skb_put(skb, bytes_written);
 		skb->protocol = eth_type_trans(skb, netdev);
 
-		if ((netdev->features & NETIF_F_RXCSUM) && !csum_not_calc) {
-			skb->csum = htons(checksum);
-			skb->ip_summed = CHECKSUM_COMPLETE;
-		}
+		/* Hardware does not provide whole packet checksum. It only
+		 * provides pseudo checksum. Since hw validates the packet
+		 * checksum but not provide us the checksum value. use
+		 * CHECSUM_UNNECESSARY.
+		 */
+		if ((netdev->features & NETIF_F_RXCSUM) && tcp_udp_csum_ok &&
+		    ipv4_csum_ok)
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
 
 		skb->dev = netdev;
 

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