[net-next PATCH 0/5] Add support for offloads with IPv6 GRE tunnels

[net-next PATCH 0/5] Add support for offloads with IPv6 GRE tunnels

[Alexander Duyck]

This patch series enables the use of segmentation and checksum offloads
with IPv6 based GRE tunnels.

In order to enable this series I had to make a change to
iptunnel_handle_offloads so that it would no longer free the skb.  This was
necessary as there were multiple paths in the IPv6 GRE code that required
the skb to still be present so it could be freed.  As it turned out I
believe this actually fixes a bug that was present in FOU/GUE based tunnels
anyway.

Below is a quick breakdown of the performance gains seen with a simple
netperf test passing traffic through a ip6gretap tunnel and then an i40e
interface:

Throughput Throughput  Local Local   Result 
           Units       CPU   Service Tag    
                       Util  Demand         
                       %  
3544.93    10^6bits/s  6.30  4.656   "before"
13081.75   10^6bits/s  3.75  0.752   "after"

---

Alexander Duyck (5):
      ip_tunnel_core: iptunnel_handle_offloads returns int and doesn't free skb
      ip6gretap: Fix MTU to allow for Ethernet header
      ip6gre: Add support for basic offloads offloads excluding GSO
      GRE: Add support for GRO/GSO of IPv6 GRE traffic
      ip6gre: Add support for GSO


 drivers/net/geneve.c            |   32 ++++++---------
 drivers/net/vxlan.c             |    6 +--
 include/net/ip_tunnels.h        |    2 -
 include/net/udp_tunnel.h        |    3 -
 net/ipv4/fou.c                  |   16 ++++----
 net/ipv4/gre_offload.c          |   14 ++++++-
 net/ipv4/ip_gre.c               |   20 +++-------
 net/ipv4/ip_tunnel_core.c       |   13 ++----
 net/ipv4/ipip.c                 |    7 +--
 net/ipv6/ip6_gre.c              |   81 +++++++++++++++++++++++++++------------
 net/ipv6/sit.c                  |   14 +++----
 net/netfilter/ipvs/ip_vs_xmit.c |    6 +--
 12 files changed, 116 insertions(+), 98 deletions(-)

[net-next PATCH 1/5] ip_tunnel_core: iptunnel_handle_offloads returns int and doesn't free skb

[Alexander Duyck]

This patch updates the IP tunnel core function iptunnel_handle_offloads so
that we return an int and do not free the skb inside the function.  This
actually allows us to clean up several paths in several tunnels so that we
can free the skb at one point in the path without having to have a
secondary path if we are supporting tunnel offloads.

In addition it should resolve some double-free issues I have found in the
tunnels paths as I believe it is possible for us to end up triggering such
an event in the case of fou or gue.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
---
 drivers/net/geneve.c            |   32 ++++++++++++--------------------
 drivers/net/vxlan.c             |    6 +++---
 include/net/ip_tunnels.h        |    2 +-
 include/net/udp_tunnel.h        |    3 +--
 net/ipv4/fou.c                  |   16 ++++++++--------
 net/ipv4/ip_gre.c               |   20 ++++++--------------
 net/ipv4/ip_tunnel_core.c       |   13 +++++--------
 net/ipv4/ipip.c                 |    7 +++----
 net/ipv6/sit.c                  |   14 ++++++--------
 net/netfilter/ipvs/ip_vs_xmit.c |    6 ++----
 10 files changed, 47 insertions(+), 72 deletions(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index a9fbf17eb256..efbc7ceedc3a 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -696,16 +696,12 @@ static int geneve_build_skb(struct rtable *rt, struct sk_buff *skb,
 	min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
 			+ GENEVE_BASE_HLEN + opt_len + sizeof(struct iphdr);
 	err = skb_cow_head(skb, min_headroom);
-	if (unlikely(err)) {
-		kfree_skb(skb);
+	if (unlikely(err))
 		goto free_rt;
-	}
 
-	skb = udp_tunnel_handle_offloads(skb, udp_sum);
-	if (IS_ERR(skb)) {
-		err = PTR_ERR(skb);
+	err = udp_tunnel_handle_offloads(skb, udp_sum);
+	if (err)
 		goto free_rt;
-	}
 
 	gnvh = (struct genevehdr *)__skb_push(skb, sizeof(*gnvh) + opt_len);
 	geneve_build_header(gnvh, tun_flags, vni, opt_len, opt);
@@ -733,16 +729,12 @@ static int geneve6_build_skb(struct dst_entry *dst, struct sk_buff *skb,
 	min_headroom = LL_RESERVED_SPACE(dst->dev) + dst->header_len
 			+ GENEVE_BASE_HLEN + opt_len + sizeof(struct ipv6hdr);
 	err = skb_cow_head(skb, min_headroom);
-	if (unlikely(err)) {
-		kfree_skb(skb);
+	if (unlikely(err))
 		goto free_dst;
-	}
 
-	skb = udp_tunnel_handle_offloads(skb, udp_sum);
-	if (IS_ERR(skb)) {
-		err = PTR_ERR(skb);
+	err = udp_tunnel_handle_offloads(skb, udp_sum);
+	if (IS_ERR(skb))
 		goto free_dst;
-	}
 
 	gnvh = (struct genevehdr *)__skb_push(skb, sizeof(*gnvh) + opt_len);
 	geneve_build_header(gnvh, tun_flags, vni, opt_len, opt);
@@ -937,7 +929,7 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 		err = geneve_build_skb(rt, skb, key->tun_flags, vni,
 				       info->options_len, opts, flags, xnet);
 		if (unlikely(err))
-			goto err;
+			goto tx_error;
 
 		tos = ip_tunnel_ecn_encap(key->tos, iip, skb);
 		ttl = key->ttl;
@@ -946,7 +938,7 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 		err = geneve_build_skb(rt, skb, 0, geneve->vni,
 				       0, NULL, flags, xnet);
 		if (unlikely(err))
-			goto err;
+			goto tx_error;
 
 		tos = ip_tunnel_ecn_encap(fl4.flowi4_tos, iip, skb);
 		ttl = geneve->ttl;
@@ -964,7 +956,7 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 
 tx_error:
 	dev_kfree_skb(skb);
-err:
+
 	if (err == -ELOOP)
 		dev->stats.collisions++;
 	else if (err == -ENETUNREACH)
@@ -1026,7 +1018,7 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 					info->options_len, opts,
 					flags, xnet);
 		if (unlikely(err))
-			goto err;
+			goto tx_error;
 
 		prio = ip_tunnel_ecn_encap(key->tos, iip, skb);
 		ttl = key->ttl;
@@ -1035,7 +1027,7 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 		err = geneve6_build_skb(dst, skb, 0, geneve->vni,
 					0, NULL, flags, xnet);
 		if (unlikely(err))
-			goto err;
+			goto tx_error;
 
 		prio = ip_tunnel_ecn_encap(ip6_tclass(fl6.flowlabel),
 					   iip, skb);
@@ -1054,7 +1046,7 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 
 tx_error:
 	dev_kfree_skb(skb);
-err:
+
 	if (err == -ELOOP)
 		dev->stats.collisions++;
 	else if (err == -ENETUNREACH)
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 7f697a3f00a4..a3bd67dce0ce 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1784,9 +1784,9 @@ static int vxlan_build_skb(struct sk_buff *skb, struct dst_entry *dst,
 	if (WARN_ON(!skb))
 		return -ENOMEM;
 
-	skb = iptunnel_handle_offloads(skb, type);
-	if (IS_ERR(skb))
-		return PTR_ERR(skb);
+	err = iptunnel_handle_offloads(skb, type);
+	if (err)
+		goto out_free;
 
 	vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
 	vxh->vx_flags = VXLAN_HF_VNI;
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 9ae9fbbccd67..6d790910ebdf 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -309,7 +309,7 @@ void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
 struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md,
 					     gfp_t flags);
 
-struct sk_buff *iptunnel_handle_offloads(struct sk_buff *skb, int gso_type_mask);
+int iptunnel_handle_offloads(struct sk_buff *skb, int gso_type_mask);
 
 static inline int iptunnel_pull_offloads(struct sk_buff *skb)
 {
diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 2dcf1de948ac..4f543262dd81 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h
@@ -105,8 +105,7 @@ struct metadata_dst *udp_tun_rx_dst(struct sk_buff *skb, unsigned short family,
 				    __be16 flags, __be64 tunnel_id,
 				    int md_size);
 
-static inline struct sk_buff *udp_tunnel_handle_offloads(struct sk_buff *skb,
-							 bool udp_csum)
+static inline int udp_tunnel_handle_offloads(struct sk_buff *skb, bool udp_csum)
 {
 	int type = udp_csum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
 
diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
index d039f8fff57f..7ac5ec87b004 100644
--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -802,11 +802,11 @@ int fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
 	int type = e->flags & TUNNEL_ENCAP_FLAG_CSUM ? SKB_GSO_UDP_TUNNEL_CSUM :
 						       SKB_GSO_UDP_TUNNEL;
 	__be16 sport;
+	int err;
 
-	skb = iptunnel_handle_offloads(skb, type);
-
-	if (IS_ERR(skb))
-		return PTR_ERR(skb);
+	err = iptunnel_handle_offloads(skb, type);
+	if (err)
+		return err;
 
 	sport = e->sport ? : udp_flow_src_port(dev_net(skb->dev),
 					       skb, 0, 0, false);
@@ -826,6 +826,7 @@ int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
 	__be16 sport;
 	void *data;
 	bool need_priv = false;
+	int err;
 
 	if ((e->flags & TUNNEL_ENCAP_FLAG_REMCSUM) &&
 	    skb->ip_summed == CHECKSUM_PARTIAL) {
@@ -836,10 +837,9 @@ int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
 
 	optlen += need_priv ? GUE_LEN_PRIV : 0;
 
-	skb = iptunnel_handle_offloads(skb, type);
-
-	if (IS_ERR(skb))
-		return PTR_ERR(skb);
+	err = iptunnel_handle_offloads(skb, type);
+	if (err)
+		return err;
 
 	/* Get source port (based on flow hash) before skb_push */
 	sport = e->sport ? : udp_flow_src_port(dev_net(skb->dev),
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index af5d1f38217f..eedd829a2f87 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -500,8 +500,7 @@ static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
 	ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol);
 }
 
-static struct sk_buff *gre_handle_offloads(struct sk_buff *skb,
-					   bool csum)
+static int gre_handle_offloads(struct sk_buff *skb, bool csum)
 {
 	return iptunnel_handle_offloads(skb, csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
 }
@@ -568,11 +567,8 @@ static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	/* Push Tunnel header. */
-	skb = gre_handle_offloads(skb, !!(tun_info->key.tun_flags & TUNNEL_CSUM));
-	if (IS_ERR(skb)) {
-		skb = NULL;
+	if (gre_handle_offloads(skb, !!(tun_info->key.tun_flags & TUNNEL_CSUM)))
 		goto err_free_rt;
-	}
 
 	flags = tun_info->key.tun_flags & (TUNNEL_CSUM | TUNNEL_KEY);
 	build_header(skb, tunnel_hlen, flags, htons(ETH_P_TEB),
@@ -640,16 +636,14 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
 		tnl_params = &tunnel->parms.iph;
 	}
 
-	skb = gre_handle_offloads(skb, !!(tunnel->parms.o_flags&TUNNEL_CSUM));
-	if (IS_ERR(skb))
-		goto out;
+	if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
+		goto free_skb;
 
 	__gre_xmit(skb, dev, tnl_params, skb->protocol);
 	return NETDEV_TX_OK;
 
 free_skb:
 	kfree_skb(skb);
-out:
 	dev->stats.tx_dropped++;
 	return NETDEV_TX_OK;
 }
@@ -664,9 +658,8 @@ static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
 		return NETDEV_TX_OK;
 	}
 
-	skb = gre_handle_offloads(skb, !!(tunnel->parms.o_flags&TUNNEL_CSUM));
-	if (IS_ERR(skb))
-		goto out;
+	if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
+		goto free_skb;
 
 	if (skb_cow_head(skb, dev->needed_headroom))
 		goto free_skb;
@@ -676,7 +669,6 @@ static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
 
 free_skb:
 	kfree_skb(skb);
-out:
 	dev->stats.tx_dropped++;
 	return NETDEV_TX_OK;
 }
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index 43445df61efd..f46c5c873831 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -146,8 +146,8 @@ struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md,
 }
 EXPORT_SYMBOL_GPL(iptunnel_metadata_reply);
 
-struct sk_buff *iptunnel_handle_offloads(struct sk_buff *skb,
-					 int gso_type_mask)
+int iptunnel_handle_offloads(struct sk_buff *skb,
+			     int gso_type_mask)
 {
 	int err;
 
@@ -159,9 +159,9 @@ struct sk_buff *iptunnel_handle_offloads(struct sk_buff *skb,
 	if (skb_is_gso(skb)) {
 		err = skb_unclone(skb, GFP_ATOMIC);
 		if (unlikely(err))
-			goto error;
+			return err;
 		skb_shinfo(skb)->gso_type |= gso_type_mask;
-		return skb;
+		return 0;
 	}
 
 	if (skb->ip_summed != CHECKSUM_PARTIAL) {
@@ -174,10 +174,7 @@ struct sk_buff *iptunnel_handle_offloads(struct sk_buff *skb,
 		skb->encapsulation = 0;
 	}
 
-	return skb;
-error:
-	kfree_skb(skb);
-	return ERR_PTR(err);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(iptunnel_handle_offloads);
 
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index ec51d02166de..92827483ee3d 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -219,9 +219,8 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (unlikely(skb->protocol != htons(ETH_P_IP)))
 		goto tx_error;
 
-	skb = iptunnel_handle_offloads(skb, SKB_GSO_IPIP);
-	if (IS_ERR(skb))
-		goto out;
+	if (iptunnel_handle_offloads(skb, SKB_GSO_IPIP))
+		goto tx_error;
 
 	skb_set_inner_ipproto(skb, IPPROTO_IPIP);
 
@@ -230,7 +229,7 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 
 tx_error:
 	kfree_skb(skb);
-out:
+
 	dev->stats.tx_errors++;
 	return NETDEV_TX_OK;
 }
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 83384308d032..a13d8c114ccb 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -913,10 +913,9 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 		goto tx_error;
 	}
 
-	skb = iptunnel_handle_offloads(skb, SKB_GSO_SIT);
-	if (IS_ERR(skb)) {
+	if (iptunnel_handle_offloads(skb, SKB_GSO_SIT)) {
 		ip_rt_put(rt);
-		goto out;
+		goto tx_error;
 	}
 
 	if (df) {
@@ -992,7 +991,6 @@ tx_error_icmp:
 	dst_link_failure(skb);
 tx_error:
 	kfree_skb(skb);
-out:
 	dev->stats.tx_errors++;
 	return NETDEV_TX_OK;
 }
@@ -1002,15 +1000,15 @@ static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	const struct iphdr  *tiph = &tunnel->parms.iph;
 
-	skb = iptunnel_handle_offloads(skb, SKB_GSO_IPIP);
-	if (IS_ERR(skb))
-		goto out;
+	if (iptunnel_handle_offloads(skb, SKB_GSO_IPIP))
+		goto tx_error;
 
 	skb_set_inner_ipproto(skb, IPPROTO_IPIP);
 
 	ip_tunnel_xmit(skb, dev, tiph, IPPROTO_IPIP);
 	return NETDEV_TX_OK;
-out:
+tx_error:
+	kfree_skb(skb);
 	dev->stats.tx_errors++;
 	return NETDEV_TX_OK;
 }
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index dc196a0f501d..6d19d2eeaa60 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -1013,8 +1013,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 	if (IS_ERR(skb))
 		goto tx_error;
 
-	skb = iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET, cp->af));
-	if (IS_ERR(skb))
+	if (iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET, cp->af)))
 		goto tx_error;
 
 	skb->transport_header = skb->network_header;
@@ -1105,8 +1104,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
 	if (IS_ERR(skb))
 		goto tx_error;
 
-	skb = iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET6, cp->af));
-	if (IS_ERR(skb))
+	if (iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET6, cp->af)))
 		goto tx_error;
 
 	skb->transport_header = skb->network_header;

[net-next PATCH 2/5] ip6gretap: Fix MTU to allow for Ethernet header

[Alexander Duyck]

When we were creating an ip6gretap interface the MTU was about 6 bytes
short of what was needed.  It turns out we were not taking the Ethernet
header into account and as a result we were eating into the 8 bytes
reserved for the encap limit.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
---
 net/ipv6/ip6_gre.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 4e636e60a360..2be66e7b4a78 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -987,6 +987,8 @@ static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu)
 				dev->mtu = rt->dst.dev->mtu - addend;
 				if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
 					dev->mtu -= 8;
+				if (dev->type == ARPHRD_ETHER)
+					dev->mtu -= ETH_HLEN;
 
 				if (dev->mtu < IPV6_MIN_MTU)
 					dev->mtu = IPV6_MIN_MTU;

[net-next PATCH 3/5] ip6gre: Add support for basic offloads offloads excluding GSO

[Alexander Duyck]

This patch adds support for the basic offloads we support on most devices.
Specifically with this patch set we can support checksum offload, basic
scatter-gather, and highdma.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
---
 net/ipv6/ip6_gre.c |   23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 2be66e7b4a78..1a5ad143be40 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -598,6 +598,18 @@ static void init_tel_txopt(struct ipv6_tel_txoption *opt, __u8 encap_limit)
 	opt->ops.opt_nflen = 8;
 }
 
+static __sum16 gre6_checksum(struct sk_buff *skb)
+{
+	__wsum csum;
+
+	if (skb->ip_summed == CHECKSUM_PARTIAL)
+		csum = lco_csum(skb);
+	else
+		csum = skb_checksum(skb, sizeof(struct ipv6hdr),
+				    skb->len - sizeof(struct ipv6hdr), 0);
+	return csum_fold(csum);
+}
+
 static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 			 struct net_device *dev,
 			 __u8 dsfield,
@@ -750,8 +762,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 		}
 		if (tunnel->parms.o_flags&GRE_CSUM) {
 			*ptr = 0;
-			*(__sum16 *)ptr = ip_compute_csum((void *)(ipv6h+1),
-				skb->len - sizeof(struct ipv6hdr));
+			*(__sum16 *)ptr = gre6_checksum(skb);
 		}
 	}
 
@@ -1507,6 +1518,11 @@ static const struct net_device_ops ip6gre_tap_netdev_ops = {
 	.ndo_get_iflink = ip6_tnl_get_iflink,
 };
 
+#define GRE6_FEATURES (NETIF_F_SG |		\
+		       NETIF_F_FRAGLIST |	\
+		       NETIF_F_HIGHDMA |		\
+		       NETIF_F_HW_CSUM)
+
 static void ip6gre_tap_setup(struct net_device *dev)
 {
 
@@ -1540,6 +1556,9 @@ static int ip6gre_newlink(struct net *src_net, struct net_device *dev,
 	nt->net = dev_net(dev);
 	ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);
 
+	dev->features		|= GRE6_FEATURES;
+	dev->hw_features	|= GRE6_FEATURES;
+
 	/* Can use a lockless transmit, unless we generate output sequences */
 	if (!(nt->parms.o_flags & GRE_SEQ))
 		dev->features |= NETIF_F_LLTX;

[net-next PATCH 4/5] GRE: Add support for GRO/GSO of IPv6 GRE traffic

[Alexander Duyck]

Since GRE doesn't really care about L3 protocol we can support IPv4 and
IPv6 using the same offloads.  With that being the case we can add a call
to register the offloads for IPv6 as a part of our GRE offload
initialization.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
---
 net/ipv4/gre_offload.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index 20557f211408..e88190a8699a 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -292,6 +292,18 @@ static const struct net_offload gre_offload = {
 
 static int __init gre_offload_init(void)
 {
-	return inet_add_offload(&gre_offload, IPPROTO_GRE);
+	int err;
+
+	err = inet_add_offload(&gre_offload, IPPROTO_GRE);
+#if IS_ENABLED(CONFIG_IPV6)
+	if (err)
+		return err;
+
+	err = inet6_add_offload(&gre_offload, IPPROTO_GRE);
+	if (err)
+		inet_del_offload(&gre_offload, IPPROTO_GRE);
+#endif
+
+	return err;
 }
 device_initcall(gre_offload_init);

[net-next PATCH 5/5] ip6gre: Add support for GSO

[Alexander Duyck]

This patch adds code borrowed from bits and pieces of other protocols to
the IPv6 GRE path so that we can support GSO over IPv6 based GRE tunnels.
By adding this support we are able to significantly improve the throughput
for GRE tunnels as we are able to make use of GSO.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
---
 net/ipv6/ip6_gre.c |   56 +++++++++++++++++++++++++++++++---------------------
 1 file changed, 33 insertions(+), 23 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 1a5ad143be40..ca5a2c5675c5 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -621,7 +621,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 	struct net *net = tunnel->net;
 	struct net_device *tdev;    /* Device to other host */
 	struct ipv6hdr  *ipv6h;     /* Our new IP header */
-	unsigned int max_headroom = 0; /* The extra header space needed */
+	unsigned int min_headroom = 0; /* The extra header space needed */
 	int    gre_hlen;
 	struct ipv6_tel_txoption opt;
 	int    mtu;
@@ -629,7 +629,6 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 	struct net_device_stats *stats = &tunnel->dev->stats;
 	int err = -1;
 	u8 proto;
-	struct sk_buff *new_skb;
 	__be16 protocol;
 
 	if (dev->type == ARPHRD_ETHER)
@@ -672,14 +671,14 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 
 	mtu = dst_mtu(dst) - sizeof(*ipv6h);
 	if (encap_limit >= 0) {
-		max_headroom += 8;
+		min_headroom += 8;
 		mtu -= 8;
 	}
 	if (mtu < IPV6_MIN_MTU)
 		mtu = IPV6_MIN_MTU;
 	if (skb_dst(skb))
 		skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
-	if (skb->len > mtu) {
+	if (skb->len > mtu && !skb_is_gso(skb)) {
 		*pmtu = mtu;
 		err = -EMSGSIZE;
 		goto tx_err_dst_release;
@@ -697,20 +696,19 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 
 	skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(dev)));
 
-	max_headroom += LL_RESERVED_SPACE(tdev) + gre_hlen + dst->header_len;
+	min_headroom += LL_RESERVED_SPACE(tdev) + gre_hlen + dst->header_len;
 
-	if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
-	    (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {
-		new_skb = skb_realloc_headroom(skb, max_headroom);
-		if (max_headroom > dev->needed_headroom)
-			dev->needed_headroom = max_headroom;
-		if (!new_skb)
-			goto tx_err_dst_release;
+	if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
+		int head_delta = SKB_DATA_ALIGN(min_headroom -
+						skb_headroom(skb) +
+						16);
 
-		if (skb->sk)
-			skb_set_owner_w(new_skb, skb->sk);
-		consume_skb(skb);
-		skb = new_skb;
+		err = pskb_expand_head(skb, max_t(int, head_delta, 0),
+				       0, GFP_ATOMIC);
+		if (min_headroom > dev->needed_headroom)
+			dev->needed_headroom = min_headroom;
+		if (unlikely(err))
+			goto tx_err_dst_release;
 	}
 
 	if (!fl6->flowi6_mark && ndst)
@@ -723,10 +721,11 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 		ipv6_push_nfrag_opts(skb, &opt.ops, &proto, NULL);
 	}
 
-	if (likely(!skb->encapsulation)) {
-		skb_reset_inner_headers(skb);
-		skb->encapsulation = 1;
-	}
+	err = iptunnel_handle_offloads(skb,
+				       (tunnel->parms.o_flags & GRE_CSUM) ?
+				       SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
+	if (err)
+		goto tx_err_dst_release;
 
 	skb_push(skb, gre_hlen);
 	skb_reset_network_header(skb);
@@ -760,7 +759,9 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 			*ptr = tunnel->parms.o_key;
 			ptr--;
 		}
-		if (tunnel->parms.o_flags&GRE_CSUM) {
+		if ((tunnel->parms.o_flags & GRE_CSUM) &&
+		    !(skb_shinfo(skb)->gso_type &
+		      (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
 			*ptr = 0;
 			*(__sum16 *)ptr = gre6_checksum(skb);
 		}
@@ -1559,9 +1560,18 @@ static int ip6gre_newlink(struct net *src_net, struct net_device *dev,
 	dev->features		|= GRE6_FEATURES;
 	dev->hw_features	|= GRE6_FEATURES;
 
-	/* Can use a lockless transmit, unless we generate output sequences */
-	if (!(nt->parms.o_flags & GRE_SEQ))
+	if (!(nt->parms.o_flags & GRE_SEQ)) {
+		/* TCP segmentation offload is not supported when we
+		 * generate output sequences.
+		 */
+		dev->features    |= NETIF_F_GSO_SOFTWARE;
+		dev->hw_features |= NETIF_F_GSO_SOFTWARE;
+
+		/* Can use a lockless transmit, unless we generate
+		 * output sequences
+		 */
 		dev->features |= NETIF_F_LLTX;
+	}
 
 	err = register_netdevice(dev);
 	if (err)

Re: [net-next PATCH 0/5] Add support for offloads with IPv6 GRE tunnels

[David Miller]

From: Alexander Duyck <aduyck@mirantis.com>
Date: Thu, 14 Apr 2016 15:33:30 -0400

> This patch series enables the use of segmentation and checksum
> offloads with IPv6 based GRE tunnels.

Series applied, nice work Alex.