sctp: extract sctp_v6_err_handle function from sctp_v6_err

This patch is to extract sctp_v6_err_handle() from sctp_v6_err() to
only handle the icmp err after the sock lookup, and it also makes
the code clearer.

sctp_v6_err_handle() will be used in sctp over udp's err handling
in the following patch.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/ipv6.c

@@ -122,50 +122,28 @@ static struct notifier_block sctp_inet6addr_notifier = {
 	.notifier_call = sctp_inet6addr_event,
 };
 
-/* ICMP error handler. */
-static int sctp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
-			u8 type, u8 code, int offset, __be32 info)
+static void sctp_v6_err_handle(struct sctp_transport *t, struct sk_buff *skb,
+			       __u8 type, __u8 code, __u32 info)
 {
-	struct sock *sk;
-	struct sctp_association *asoc;
-	struct sctp_transport *transport;
+	struct sctp_association *asoc = t->asoc;
+	struct sock *sk = asoc->base.sk;
 	struct ipv6_pinfo *np;
-	__u16 saveip, savesctp;
-	int err, ret = 0;
-	struct net *net = dev_net(skb->dev);
-
-	/* Fix up skb to look at the embedded net header. */
-	saveip	 = skb->network_header;
-	savesctp = skb->transport_header;
-	skb_reset_network_header(skb);
-	skb_set_transport_header(skb, offset);
-	sk = sctp_err_lookup(net, AF_INET6, skb, sctp_hdr(skb), &asoc, &transport);
-	/* Put back, the original pointers. */
-	skb->network_header   = saveip;
-	skb->transport_header = savesctp;
-	if (!sk) {
-		__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
-		return -ENOENT;
-	}
-
-	/* Warning:  The sock lock is held.  Remember to call
-	 * sctp_err_finish!
-	 */
+	int err = 0;
 
 	switch (type) {
 	case ICMPV6_PKT_TOOBIG:
 		if (ip6_sk_accept_pmtu(sk))
-			sctp_icmp_frag_needed(sk, asoc, transport, ntohl(info));
-		goto out_unlock;
+			sctp_icmp_frag_needed(sk, asoc, t, info);
+		return;
 	case ICMPV6_PARAMPROB:
 		if (ICMPV6_UNK_NEXTHDR == code) {
-			sctp_icmp_proto_unreachable(sk, asoc, transport);
-			goto out_unlock;
+			sctp_icmp_proto_unreachable(sk, asoc, t);
+			return;
 		}
 		break;
 	case NDISC_REDIRECT:
-		sctp_icmp_redirect(sk, transport, skb);
-		goto out_unlock;
+		sctp_icmp_redirect(sk, t, skb);
+		return;
 	default:
 		break;
 	}
@@ -175,13 +153,39 @@ static int sctp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	if (!sock_owned_by_user(sk) && np->recverr) {
 		sk->sk_err = err;
 		sk->sk_error_report(sk);
-	} else {  /* Only an error on timeout */
+	} else {
 		sk->sk_err_soft = err;
 	}
+}
+
+/* ICMP error handler. */
+static int sctp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+		       u8 type, u8 code, int offset, __be32 info)
+{
+	struct net *net = dev_net(skb->dev);
+	struct sctp_transport *transport;
+	struct sctp_association *asoc;
+	__u16 saveip, savesctp;
+	struct sock *sk;
+
+	/* Fix up skb to look at the embedded net header. */
+	saveip	 = skb->network_header;
+	savesctp = skb->transport_header;
+	skb_reset_network_header(skb);
+	skb_set_transport_header(skb, offset);
+	sk = sctp_err_lookup(net, AF_INET6, skb, sctp_hdr(skb), &asoc, &transport);
+	/* Put back, the original pointers. */
+	skb->network_header   = saveip;
+	skb->transport_header = savesctp;
+	if (!sk) {
+		__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
+		return -ENOENT;
+	}
 
-out_unlock:
+	sctp_v6_err_handle(transport, skb, type, code, ntohl(info));
 	sctp_err_finish(sk, transport);
-	return ret;
+
+	return 0;
 }
 
 static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *t)