[PATCH 3.10 084/268] netvsc: reduce maximum GSO size

Willy Tarreau
2017-06-19T19:22:57Z

From: stephen hemminger <stephen@networkplumber.org>

commit a50af86dd49ee1851d1ccf06dd0019c05b95e297 upstream.

Hyper-V (and Azure) support using NVGRE which requires some extra space
for encapsulation headers. Because of this the largest allowed TSO
packet is reduced.

For older releases, hard code a fixed reduced value. For next release,
there is a better solution which uses result of host offload
negotiation.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
drivers/net/hyperv/netvsc_drv.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 59e9c56..4934604 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -48,6 +48,9 @@ struct net_device_context {
struct work_struct work;
};

+/* Restrict GSO size to account for NVGRE */
+#define NETVSC_GSO_MAX_SIZE 62768
+
#define RING_SIZE_MIN 64
static int ring_size = 128;
module_param(ring_size, int, S_IRUGO);
@@ -436,6 +439,7 @@ static int netvsc_probe(struct hv_device *dev,

SET_ETHTOOL_OPS(net, &ethtool_ops);
SET_NETDEV_DEV(net, &dev->device);
+ netif_set_gso_max_size(net, NETVSC_GSO_MAX_SIZE);

ret = register_netdev(net);
if (ret != 0) {
--
2.8.0.rc2.1.gbe9624a