Extract the dst lookup logic from ipip6_tunnel_xmit() into new helper
ipip6_tunnel_dst_find() to reduce code duplication and enhance readability.

No functional change intended.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
---
 net/ipv6/sit.c | 93 +++++++++++++++++++++++---------------------------
 1 file changed, 43 insertions(+), 50 deletions(-)

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 12496ba1b7d4..bcd261ff985b 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -848,6 +848,47 @@ static inline __be32 try_6rd(struct ip_tunnel *tunnel,
 	return dst;
 }
 
+static bool ipip6_tunnel_dst_find(struct sk_buff *skb, __be32 *dst,
+				  bool is_isatap)
+{
+	const struct ipv6hdr *iph6 = ipv6_hdr(skb);
+	struct neighbour *neigh = NULL;
+	const struct in6_addr *addr6;
+	bool found = false;
+	int addr_type;
+
+	if (skb_dst(skb))
+		neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
+
+	if (!neigh) {
+		net_dbg_ratelimited("nexthop == NULL\n");
+		return found;
+	}
+
+	addr6 = (const struct in6_addr *)&neigh->primary_key;
+	addr_type = ipv6_addr_type(addr6);
+
+	if (is_isatap) {
+		if ((addr_type & IPV6_ADDR_UNICAST) &&
+		    ipv6_addr_is_isatap(addr6)) {
+			*dst = addr6->s6_addr32[3];
+			found = true;
+		}
+	} else {
+		if (addr_type == IPV6_ADDR_ANY) {
+			addr6 = &ipv6_hdr(skb)->daddr;
+			addr_type = ipv6_addr_type(addr6);
+		}
+
+		if ((addr_type & IPV6_ADDR_COMPATv4) != 0) {
+			*dst = addr6->s6_addr32[3];
+			found = true;
+		}
+	}
+	neigh_release(neigh);
+	return found;
+}
+
 /*
  *	This function assumes it is being called from dev_queue_xmit()
  *	and that skb is filled properly by that function.
@@ -867,8 +908,6 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 	__be32 dst = tiph->daddr;
 	struct flowi4 fl4;
 	int    mtu;
-	const struct in6_addr *addr6;
-	int addr_type;
 	u8 ttl;
 	u8 protocol = IPPROTO_IPV6;
 	int t_hlen = tunnel->hlen + sizeof(struct iphdr);
@@ -878,28 +917,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 
 	/* ISATAP (RFC4214) - must come before 6to4 */
 	if (dev->priv_flags & IFF_ISATAP) {
-		struct neighbour *neigh = NULL;
-		bool do_tx_error = false;
-
-		if (skb_dst(skb))
-			neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
-
-		if (!neigh) {
-			net_dbg_ratelimited("nexthop == NULL\n");
-			goto tx_error;
-		}
-
-		addr6 = (const struct in6_addr *)&neigh->primary_key;
-		addr_type = ipv6_addr_type(addr6);
-
-		if ((addr_type & IPV6_ADDR_UNICAST) &&
-		     ipv6_addr_is_isatap(addr6))
-			dst = addr6->s6_addr32[3];
-		else
-			do_tx_error = true;
-
-		neigh_release(neigh);
-		if (do_tx_error)
+		if (!ipip6_tunnel_dst_find(skb, &dst, true))
 			goto tx_error;
 	}
 
@@ -907,32 +925,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
 		dst = try_6rd(tunnel, &iph6->daddr);
 
 	if (!dst) {
-		struct neighbour *neigh = NULL;
-		bool do_tx_error = false;
-
-		if (skb_dst(skb))
-			neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
-
-		if (!neigh) {
-			net_dbg_ratelimited("nexthop == NULL\n");
-			goto tx_error;
-		}
-
-		addr6 = (const struct in6_addr *)&neigh->primary_key;
-		addr_type = ipv6_addr_type(addr6);
-
-		if (addr_type == IPV6_ADDR_ANY) {
-			addr6 = &ipv6_hdr(skb)->daddr;
-			addr_type = ipv6_addr_type(addr6);
-		}
-
-		if ((addr_type & IPV6_ADDR_COMPATv4) != 0)
-			dst = addr6->s6_addr32[3];
-		else
-			do_tx_error = true;
-
-		neigh_release(neigh);
-		if (do_tx_error)
+		if (!ipip6_tunnel_dst_find(skb, &dst, false))
 			goto tx_error;
 	}
 
-- 
2.34.1