Merge branch 'veth-and-GSO-maximums'

Stephen Hemminger says:

====================
veth and GSO maximums

This is the more general way to solving the issue of GSO limits
not being set correctly for containers on Azure. If a GSO packet
is sent to host that exceeds the limit (reported by NDIS), then
the host is forced to do segmentation in software which has noticeable
performance impact.

The core rtnetlink infrastructure already has the messages and
infrastructure to allow changing gso limits. With an updated iproute2
the following already works:
  # ip li set dev dummy0 gso_max_size 30000

These patches are about making it easier with veth.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/veth.c

@@ -410,6 +410,9 @@ static int veth_newlink(struct net *src_net, struct net_device *dev,
 	if (ifmp && (dev->ifindex != 0))
 		peer->ifindex = ifmp->ifi_index;
 
+	peer->gso_max_size = dev->gso_max_size;
+	peer->gso_max_segs = dev->gso_max_segs;
+
 	err = register_netdevice(peer);
 	put_net(net);
 	net = NULL;

net/core/rtnetlink.c

@@ -1637,6 +1637,8 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
 	[IFLA_PROMISCUITY]	= { .type = NLA_U32 },
 	[IFLA_NUM_TX_QUEUES]	= { .type = NLA_U32 },
 	[IFLA_NUM_RX_QUEUES]	= { .type = NLA_U32 },
+	[IFLA_GSO_MAX_SEGS]	= { .type = NLA_U32 },
+	[IFLA_GSO_MAX_SIZE]	= { .type = NLA_U32 },
 	[IFLA_PHYS_PORT_ID]	= { .type = NLA_BINARY, .len = MAX_PHYS_ITEM_ID_LEN },
 	[IFLA_CARRIER_CHANGES]	= { .type = NLA_U32 },  /* ignored */
 	[IFLA_PHYS_SWITCH_ID]	= { .type = NLA_BINARY, .len = MAX_PHYS_ITEM_ID_LEN },
@@ -2287,6 +2289,34 @@ static int do_setlink(const struct sk_buff *skb,
 		}
 	}
 
+	if (tb[IFLA_GSO_MAX_SIZE]) {
+		u32 max_size = nla_get_u32(tb[IFLA_GSO_MAX_SIZE]);
+
+		if (max_size > GSO_MAX_SIZE) {
+			err = -EINVAL;
+			goto errout;
+		}
+
+		if (dev->gso_max_size ^ max_size) {
+			netif_set_gso_max_size(dev, max_size);
+			status |= DO_SETLINK_MODIFIED;
+		}
+	}
+
+	if (tb[IFLA_GSO_MAX_SEGS]) {
+		u32 max_segs = nla_get_u32(tb[IFLA_GSO_MAX_SEGS]);
+
+		if (max_segs > GSO_MAX_SEGS) {
+			err = -EINVAL;
+			goto errout;
+		}
+
+		if (dev->gso_max_segs ^ max_segs) {
+			dev->gso_max_segs = max_segs;
+			status |= DO_SETLINK_MODIFIED;
+		}
+	}
+
 	if (tb[IFLA_OPERSTATE])
 		set_operstate(dev, nla_get_u8(tb[IFLA_OPERSTATE]));
 
@@ -2651,6 +2681,10 @@ struct net_device *rtnl_create_link(struct net *net,
 		dev->link_mode = nla_get_u8(tb[IFLA_LINKMODE]);
 	if (tb[IFLA_GROUP])
 		dev_set_group(dev, nla_get_u32(tb[IFLA_GROUP]));
+	if (tb[IFLA_GSO_MAX_SIZE])
+		netif_set_gso_max_size(dev, nla_get_u32(tb[IFLA_GSO_MAX_SIZE]));
+	if (tb[IFLA_GSO_MAX_SEGS])
+		dev->gso_max_size = nla_get_u32(tb[IFLA_GSO_MAX_SEGS]);
 
 	return dev;
 }