gre: export gre_build_header() function.

This is required for ovs gre module.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 35 insertions, 39 deletions

diff --git a/include/net/gre.h b/include/net/gre.h
index c6ea0c72c605..cbb9d51d82c1 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -32,6 +32,8 @@ 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 int ip_gre_calc_hlen(__be16 o_flags)
 {
diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c
index 8b9a373890ab..1cbc46536d1f 100644
--- a/net/ipv4/gre.c
+++ b/net/ipv4/gre.c
@@ -61,6 +61,38 @@ 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);
+
+        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)) {
+                        *ptr = 0;
+                        *(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0,
+                                                                 skb->len, 0));
+                }
+        }
+}
+EXPORT_SYMBOL_GPL(gre_build_header);
+
 static __sum16 check_checksum(struct sk_buff *skb)
 {
         __sum16 csum = 0;
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 19863a81cea1..362c7c4c13ca 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -248,40 +248,6 @@ error:
         return ERR_PTR(err);
 }
 
-static struct sk_buff *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);
-
-        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)) {
-                        *(__sum16 *)ptr = 0;
-                        *(__sum16 *)ptr = csum_fold(skb_checksum(skb, 0,
-                                                                 skb->len, 0));
-                }
-        }
-
-        return skb;
-}
-
 static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
                        const struct iphdr *tnl_params,
                        __be16 proto)
@@ -302,11 +268,7 @@ static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
         tpi.seq = htonl(tunnel->o_seqno);
 
         /* Push GRE header. */
-        skb = gre_build_header(skb, &tpi, tunnel->hlen);
-        if (unlikely(!skb)) {
-                dev->stats.tx_dropped++;
-                return;
-        }
+        gre_build_header(skb, &tpi, tunnel->hlen);
 
         ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol);
 }