[PATCH AUTOSEL for 4.9 092/219] vxlan: vxlan dev should inherit lowerdev's gso_max_size

[Sasha Levin]

From: Felix Manlunas <felix.manlunas@xxxxxxxxxx>

[ Upstream commit d6acfeb17d030bb3907e77c048b0e7783ad8e5a9 ]

vxlan dev currently ignores lowerdev's gso_max_size, which adversely
affects TSO performance of liquidio if it's the lowerdev.  Egress TCP
packets' skb->len often exceed liquidio's advertised gso_max_size.  This
may happen on other NIC drivers.

Fix it by assigning lowerdev's gso_max_size to that of vxlan dev.  Might as
well do likewise for gso_max_segs.

Single flow TSO throughput of liquidio as lowerdev (using iperf3):

    Before the patch:    139 Mbps
    After the patch :   8.68 Gbps
    Percent increase:  6,144 %

Signed-off-by: Felix Manlunas <felix.manlunas@xxxxxxxxxx>
Signed-off-by: Satanand Burla <satananda.burla@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/net/vxlan.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 983e941bdf29..50570d779b01 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2912,6 +2912,11 @@ static int vxlan_dev_configure(struct net *src_net, struct net_device *dev,
 		return -EINVAL;
 	}
 
+	if (lowerdev) {
+		dev->gso_max_size = lowerdev->gso_max_size;
+		dev->gso_max_segs = lowerdev->gso_max_segs;
+	}
+
 	if (conf->mtu) {
 		err = __vxlan_change_mtu(dev, lowerdev, dst, conf->mtu, false);
 		if (err)
-- 
2.14.1