ipv6: separate ndisc_ns_create() from ndisc_send_ns()

This patch separate NS message allocation steps from ndisc_send_ns(),
so it could be used in other places, like bonding, to allocate and
send IPv6 NS message.

Also export ndisc_send_skb() and ndisc_ns_create() for later bonding usage.
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ndisc.h

@@ -447,10 +447,15 @@ void ndisc_cleanup(void);
 
 int ndisc_rcv(struct sk_buff *skb);
 
+struct sk_buff *ndisc_ns_create(struct net_device *dev, const struct in6_addr *solicit,
+				const struct in6_addr *saddr, u64 nonce);
 void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,
 		   const struct in6_addr *daddr, const struct in6_addr *saddr,
 		   u64 nonce);
 
+void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr,
+		    const struct in6_addr *saddr);
+
 void ndisc_send_rs(struct net_device *dev,
 		   const struct in6_addr *saddr, const struct in6_addr *daddr);
 void ndisc_send_na(struct net_device *dev, const struct in6_addr *daddr,

net/ipv6/ndisc.c

@@ -466,8 +466,7 @@ static void ip6_nd_hdr(struct sk_buff *skb,
 	hdr->daddr = *daddr;
 }
 
-static void ndisc_send_skb(struct sk_buff *skb,
-			   const struct in6_addr *daddr,
+void ndisc_send_skb(struct sk_buff *skb, const struct in6_addr *daddr,
 		    const struct in6_addr *saddr)
 {
 	struct dst_entry *dst = skb_dst(skb);
@@ -515,6 +514,7 @@ static void ndisc_send_skb(struct sk_buff *skb,
 
 	rcu_read_unlock();
 }
+EXPORT_SYMBOL(ndisc_send_skb);
 
 void ndisc_send_na(struct net_device *dev, const struct in6_addr *daddr,
 		   const struct in6_addr *solicited_addr,
@@ -598,22 +598,16 @@ static void ndisc_send_unsol_na(struct net_device *dev)
 	in6_dev_put(idev);
 }
 
-void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,
-		   const struct in6_addr *daddr, const struct in6_addr *saddr,
-		   u64 nonce)
+struct sk_buff *ndisc_ns_create(struct net_device *dev, const struct in6_addr *solicit,
+				const struct in6_addr *saddr, u64 nonce)
 {
-	struct sk_buff *skb;
-	struct in6_addr addr_buf;
 	int inc_opt = dev->addr_len;
-	int optlen = 0;
+	struct sk_buff *skb;
 	struct nd_msg *msg;
+	int optlen = 0;
 
-	if (!saddr) {
-		if (ipv6_get_lladdr(dev, &addr_buf,
-				   (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)))
-			return;
-		saddr = &addr_buf;
-	}
+	if (!saddr)
+		return NULL;
 
 	if (ipv6_addr_any(saddr))
 		inc_opt = false;
@@ -625,7 +619,7 @@ void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,
 
 	skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);
 	if (!skb)
-		return;
+		return NULL;
 
 	msg = skb_put(skb, sizeof(*msg));
 	*msg = (struct nd_msg) {
@@ -647,6 +641,27 @@ void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,
 		memcpy(opt + 2, &nonce, 6);
 	}
 
+	return skb;
+}
+EXPORT_SYMBOL(ndisc_ns_create);
+
+void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,
+		   const struct in6_addr *daddr, const struct in6_addr *saddr,
+		   u64 nonce)
+{
+	struct in6_addr addr_buf;
+	struct sk_buff *skb;
+
+	if (!saddr) {
+		if (ipv6_get_lladdr(dev, &addr_buf,
+				    (IFA_F_TENTATIVE | IFA_F_OPTIMISTIC)))
+			return;
+		saddr = &addr_buf;
+	}
+
+	skb = ndisc_ns_create(dev, solicit, saddr, nonce);
+
+	if (skb)
 		ndisc_send_skb(skb, daddr, saddr);
 }