openvswitch: Use regular GRE net_device instead of vport

This change “openvswitch: Use regular GRE net_device instead of vport” in Linux kernel is authored by Pravin B Shelar <pshelar [at] nicira.com> on Fri Aug 7 23:51:47 2015 -0700.

openvswitch: Use regular GRE net_device instead of vport

Using GRE tunnel meta data collection feature, we can implement
OVS GRE vport. This patch removes all of the OVS
specific GRE code and make OVS use a ip_gre net_device.
Minimal GRE vport is kept to handle compatibility with
current userspace application.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit b2acd1d.

There are 321 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 include/net/gre.h           |  12 +--
 net/ipv4/gre_demux.c        |  34 -------
 net/ipv4/ip_gre.c           |  36 +++++++
 net/openvswitch/Kconfig     |   2 +-
 net/openvswitch/vport-gre.c | 237 ++++----------------------------------------
 5 files changed, 61 insertions(+), 260 deletions(-)

diff --git a/include/net/gre.h b/include/net/gre.h
index b531820..e3e0845 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -33,16 +33,8 @@ struct gre_cisco_protocol {
 int gre_cisco_register(struct gre_cisco_protocol *proto);
 int gre_cisco_unregister(struct gre_cisco_protocol *proto);
 
-void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
-		      int hdr_len);
-
-static inline struct sk_buff *gre_handle_offloads(struct sk_buff *skb,
-						  bool csum)
-{
-	return iptunnel_handle_offloads(skb, csum,
-					csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
-}
-
+struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
+				       u8 name_assign_type);
 
 static inline int ip_gre_calc_hlen(__be16 o_flags)
 {
diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index 4a7b5b2..77562e0 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -61,40 +61,6 @@ int gre_del_protocol(const struct gre_protocol *proto, u8 version)
 }
 EXPORT_SYMBOL_GPL(gre_del_protocol);
 
-void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
-		      int hdr_len)
-{
-	struct gre_base_hdr *greh;
-
-	skb_push(skb, hdr_len);
-
-	skb_reset_transport_header(skb);
-	greh = (struct gre_base_hdr *)skb->data;
-	greh->flags = tnl_flags_to_gre_flags(tpi->flags);
-	greh->protocol = tpi->proto;
-
-	if (tpi->flags&(TUNNEL_KEY|TUNNEL_CSUM|TUNNEL_SEQ)) {
-		__be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
-
-		if (tpi->flags&TUNNEL_SEQ) {
-			*ptr = tpi->seq;
-			ptr--;
-		}
-		if (tpi->flags&TUNNEL_KEY) {
-			*ptr = tpi->key;
-			ptr--;
-		}
-		if (tpi->flags&TUNNEL_CSUM &&
-		    !(skb_shinfo(skb)->gso_type &
-		      (SKB_GSO_GRE|SKB_GSO_GRE_CSUM))) {
-			*ptr = 0;
-			*(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0,
-								 skb->len, 0));
-		}
-	}
-}
-EXPORT_SYMBOL_GPL(gre_build_header);
-
 static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
 			    bool *csum_err)
 {
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 554a760..49d1402 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -318,6 +318,13 @@ 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)
+{
+	return iptunnel_handle_offloads(skb, csum,
+					csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
+}
+
 static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct ip_tunnel_info *tun_info;
@@ -1012,6 +1019,35 @@ static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	.get_link_net	= ip_tunnel_get_link_net,
 };
 
+struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
+					u8 name_assign_type)
+{
+	struct nlattr *tb[IFLA_MAX + 1];
+	struct net_device *dev;
+	struct ip_tunnel *t;
+	int err;
+
+	memset(&tb, 0, sizeof(tb));
+
+	dev = rtnl_create_link(net, name, name_assign_type,
+			       &ipgre_tap_ops, tb);
+	if (IS_ERR(dev))
+		return dev;
+
+	/* Configure flow based GRE device. */
+	t = netdev_priv(dev);
+	t->collect_md = true;
+
+	err = ipgre_newlink(net, dev, tb, NULL);
+	if (err < 0)
+		goto out;
+	return dev;
+out:
+	free_netdev(dev);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(gretap_fb_dev_create);
+
 static int __net_init ipgre_tap_init_net(struct net *net)
 {
 	return ip_tunnel_init_net(net, gre_tap_net_id, &ipgre_tap_ops, "gretap0");
diff --git a/net/openvswitch/Kconfig b/net/openvswitch/Kconfig
index 1584040..422dc05 100644
--- a/net/openvswitch/Kconfig
+++ b/net/openvswitch/Kconfig
@@ -34,7 +34,7 @@ config OPENVSWITCH
 config OPENVSWITCH_GRE
 	tristate "Open vSwitch GRE tunneling support"
 	depends on OPENVSWITCH
-	depends on NET_IPGRE_DEMUX
+	depends on NET_IPGRE
 	default OPENVSWITCH
 	---help---
 	  If you say Y here, then the Open vSwitch will be able create GRE
diff --git a/net/openvswitch/vport-gre.c b/net/openvswitch/vport-gre.c
index b87656c..871801d 100644
--- a/net/openvswitch/vport-gre.c
+++ b/net/openvswitch/vport-gre.c
@@ -45,235 +45,43 @@
 
 #include "datapath.h"
 #include "vport.h"
+#include "vport-netdev.h"
 
 static struct vport_ops ovs_gre_vport_ops;
 
-/* Returns the least-significant 32 bits of a __be64. */
-static __be32 be64_get_low32(__be64 x)
+static struct vport *gre_tnl_create(const struct vport_parms *parms)
 {
-#ifdef __BIG_ENDIAN
-	return (__force __be32)x;
-#else
-	return (__force __be32)((__force u64)x >> 32);
-#endif
-}
-
-static __be16 filter_tnl_flags(__be16 flags)
-{
-	return flags & (TUNNEL_CSUM | TUNNEL_KEY);
-}
-
-static struct sk_buff *__build_header(struct sk_buff *skb,
-				      int tunnel_hlen)
-{
-	struct tnl_ptk_info tpi;
-	const struct ip_tunnel_key *tun_key;
-
-	tun_key = &OVS_CB(skb)->egress_tun_info->key;
-
-	skb = gre_handle_offloads(skb, !!(tun_key->tun_flags & TUNNEL_CSUM));
-	if (IS_ERR(skb))
-		return skb;
-
-	tpi.flags = filter_tnl_flags(tun_key->tun_flags);
-	tpi.proto = htons(ETH_P_TEB);
-	tpi.key = be64_get_low32(tun_key->tun_id);
-	tpi.seq = 0;
-	gre_build_header(skb, &tpi, tunnel_hlen);
-
-	return skb;
-}
-
-static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
-{
-#ifdef __BIG_ENDIAN
-	return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
-#else
-	return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
-#endif
-}
-
-/* Called with rcu_read_lock and BH disabled. */
-static int gre_rcv(struct sk_buff *skb,
-		   const struct tnl_ptk_info *tpi)
-{
-	struct ip_tunnel_info tun_info;
-	struct ovs_net *ovs_net;
-	struct vport *vport;
-	__be64 key;
-
-	ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
-	vport = rcu_dereference(ovs_net->vport_net.gre_vport);
-	if (unlikely(!vport))
-		return PACKET_REJECT;
-
-	key = key_to_tunnel_id(tpi->key, tpi->seq);
-	ip_tunnel_info_init(&tun_info, ip_hdr(skb), 0, 0, key,
-			    filter_tnl_flags(tpi->flags), NULL, 0);
-
-	ovs_vport_receive(vport, skb, &tun_info);
-	return PACKET_RCVD;
-}
-
-/* Called with rcu_read_lock and BH disabled. */
-static int gre_err(struct sk_buff *skb, u32 info,
-		   const struct tnl_ptk_info *tpi)
-{
-	struct ovs_net *ovs_net;
+	struct net *net = ovs_dp_get_net(parms->dp);
+	struct net_device *dev;
 	struct vport *vport;
 
-	ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
-	vport = rcu_dereference(ovs_net->vport_net.gre_vport);
-
-	if (unlikely(!vport))
-		return PACKET_REJECT;
-	else
-		return PACKET_RCVD;
-}
-
-static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
-{
-	struct net *net = ovs_dp_get_net(vport->dp);
-	const struct ip_tunnel_key *tun_key;
-	struct flowi4 fl;
-	struct rtable *rt;
-	int min_headroom;
-	int tunnel_hlen;
-	__be16 df;
-	int err;
-
-	if (unlikely(!OVS_CB(skb)->egress_tun_info)) {
-		err = -EINVAL;
-		goto err_free_skb;
-	}
-
-	tun_key = &OVS_CB(skb)->egress_tun_info->key;
-	rt = ovs_tunnel_route_lookup(net, tun_key, skb->mark, &fl, IPPROTO_GRE);
-	if (IS_ERR(rt)) {
-		err = PTR_ERR(rt);
-		goto err_free_skb;
-	}
-
-	tunnel_hlen = ip_gre_calc_hlen(tun_key->tun_flags);
-
-	min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
-			+ tunnel_hlen + sizeof(struct iphdr)
-			+ (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0);
-	if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
-		int head_delta = SKB_DATA_ALIGN(min_headroom -
-						skb_headroom(skb) +
-						16);
-		err = pskb_expand_head(skb, max_t(int, head_delta, 0),
-					0, GFP_ATOMIC);
-		if (unlikely(err))
-			goto err_free_rt;
-	}
-
-	skb = vlan_hwaccel_push_inside(skb);
-	if (unlikely(!skb)) {
-		err = -ENOMEM;
-		goto err_free_rt;
-	}
-
-	/* Push Tunnel header. */
-	skb = __build_header(skb, tunnel_hlen);
-	if (IS_ERR(skb)) {
-		err = PTR_ERR(skb);
-		skb = NULL;
-		goto err_free_rt;
+	vport = ovs_vport_alloc(0, &ovs_gre_vport_ops, parms);
+	if (IS_ERR(vport))
+		return vport;
+
+	rtnl_lock();
+	dev = gretap_fb_dev_create(net, parms->name, NET_NAME_USER);
+	if (IS_ERR(dev)) {
+		rtnl_unlock();
+		ovs_vport_free(vport);
+		return ERR_CAST(dev);
 	}
 
-	df = tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
-		htons(IP_DF) : 0;
-
-	skb->ignore_df = 1;
-
-	return iptunnel_xmit(skb->sk, rt, skb, fl.saddr,
-			     tun_key->ipv4_dst, IPPROTO_GRE,
-			     tun_key->ipv4_tos, tun_key->ipv4_ttl, df, false);
-err_free_rt:
-	ip_rt_put(rt);
-err_free_skb:
-	kfree_skb(skb);
-	return err;
-}
-
-static struct gre_cisco_protocol gre_protocol = {
-	.handler        = gre_rcv,
-	.err_handler    = gre_err,
-	.priority       = 1,
-};
-
-static int gre_ports;
-static int gre_init(void)
-{
-	int err;
-
-	gre_ports++;
-	if (gre_ports > 1)
-		return 0;
-
-	err = gre_cisco_register(&gre_protocol);
-	if (err)
-		pr_warn("cannot register gre protocol handlern");
-
-	return err;
-}
-
-static void gre_exit(void)
-{
-	gre_ports--;
-	if (gre_ports > 0)
-		return;
-
-	gre_cisco_unregister(&gre_protocol);
-}
+	dev_change_flags(dev, dev->flags | IFF_UP);
+	rtnl_unlock();
 
-static const char *gre_get_name(const struct vport *vport)
-{
-	return vport_priv(vport);
+	return vport;
 }
 
 static struct vport *gre_create(const struct vport_parms *parms)
 {
-	struct net *net = ovs_dp_get_net(parms->dp);
-	struct ovs_net *ovs_net;
 	struct vport *vport;
-	int err;
-
-	err = gre_init();
-	if (err)
-		return ERR_PTR(err);
-
-	ovs_net = net_generic(net, ovs_net_id);
-	if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
-		vport = ERR_PTR(-EEXIST);
-		goto error;
-	}
 
-	vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
+	vport = gre_tnl_create(parms);
 	if (IS_ERR(vport))
-		goto error;
-
-	strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
-	rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
-	return vport;
-
-error:
-	gre_exit();
-	return vport;
-}
-
-static void gre_tnl_destroy(struct vport *vport)
-{
-	struct net *net = ovs_dp_get_net(vport->dp);
-	struct ovs_net *ovs_net;
-
-	ovs_net = net_generic(net, ovs_net_id);
+		return vport;
 
-	RCU_INIT_POINTER(ovs_net->vport_net.gre_vport, NULL);
-	ovs_vport_deferred_free(vport);
-	gre_exit();
+	return ovs_netdev_link(vport, parms->name);
 }
 
 static int gre_get_egress_tun_info(struct vport *vport, struct sk_buff *skb,
@@ -288,10 +96,9 @@ static int gre_get_egress_tun_info(struct vport *vport, struct sk_buff *skb,
 static struct vport_ops ovs_gre_vport_ops = {
 	.type		= OVS_VPORT_TYPE_GRE,
 	.create		= gre_create,
-	.destroy	= gre_tnl_destroy,
-	.get_name	= gre_get_name,
-	.send		= gre_tnl_send,
+	.send		= ovs_netdev_send,
 	.get_egress_tun_info	= gre_get_egress_tun_info,
+	.destroy	= ovs_netdev_tunnel_destroy,
 	.owner		= THIS_MODULE,
 };
 

The commit for this change in Linux stable tree is b2acd1d (patch).

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