ipv4: Prepare for change of rt->rt_iif encoding.

Use inet_iif() consistently, and for TCP record the input interface of
cached RX dst in inet sock.

rt->rt_iif is going to be encoded differently, so that we can
legitimately cache input routes in the FIB info more aggressively.

When the input interface is "use SKB device index" the rt->rt_iif will
be set to zero.

This forces us to move the TCP RX dst cache installation into the ipv4
specific code, and as well it should since doing the route caching for
ipv6 is pointless at the moment since it is not inspected in the ipv6
input paths yet.

Also, remove the unlikely on dst->obsolete, all ipv4 dsts have
obsolete set to a non-zero value to force invocation of the check
callback.

Signed-off-by: David S. Miller <davem@davemloft.net>

9 files changed, 26 insertions, 27 deletions

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 25428d0c50c..176ecdba4a2 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -481,7 +481,7 @@ static struct dst_entry* dccp_v4_route_skb(struct net *net, struct sock *sk,
 	struct rtable *rt;
 	const struct iphdr *iph = ip_hdr(skb);
 	struct flowi4 fl4 = {
-		.flowi4_oif = skb_rtable(skb)->rt_iif,
+		.flowi4_oif = inet_iif(skb),
 		.daddr = iph->saddr,
 		.saddr = iph->daddr,
 		.flowi4_tos = RT_CONN_FLAGS(sk),
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index f2a06beffbd..f2eccd53174 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -571,7 +571,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 		rcu_read_lock();
 		if (rt_is_input_route(rt) &&
 		    net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
-			dev = dev_get_by_index_rcu(net, rt->rt_iif);
+			dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 
 		if (dev)
 			saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index de29f46f68b..5eea4a81104 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1027,10 +1027,9 @@ e_inval:
 void ipv4_pktinfo_prepare(struct sk_buff *skb)
 {
 	struct in_pktinfo *pktinfo = PKTINFO_SKB_CB(skb);
-	const struct rtable *rt = skb_rtable(skb);
 
-	if (rt) {
-		pktinfo->ipi_ifindex = rt->rt_iif;
+	if (skb_rtable(skb)) {
+		pktinfo->ipi_ifindex = inet_iif(skb);
 		pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);
 	} else {
 		pktinfo->ipi_ifindex = 0;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 34017be87c8..f6be7811939 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -848,7 +848,7 @@ void ip_rt_send_redirect(struct sk_buff *skb)
 		if (log_martians &&
 		    peer->rate_tokens == ip_rt_redirect_number)
 			net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
-					     &ip_hdr(skb)->saddr, rt->rt_iif,
+					     &ip_hdr(skb)->saddr, inet_iif(skb),
 					     &ip_hdr(skb)->daddr, &rt->rt_gateway);
 #endif
 	}
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 21d7f8f3a7a..3e07a64ca44 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5391,18 +5391,6 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
-	if (sk->sk_rx_dst) {
-		struct dst_entry *dst = sk->sk_rx_dst;
-		if (unlikely(dst->obsolete)) {
-			if (dst->ops->check(dst, 0) == NULL) {
-				dst_release(dst);
-				sk->sk_rx_dst = NULL;
-			}
-		}
-	}
-	if (unlikely(sk->sk_rx_dst == NULL))
-		sk->sk_rx_dst = dst_clone(skb_dst(skb));
-
 	/*
 	 *	Header prediction.
 	 *	The code loosely follows the one in the famous
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index bc5432e3c77..3e30548ac32 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1618,6 +1618,20 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 
 	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
 		sock_rps_save_rxhash(sk, skb);
+		if (sk->sk_rx_dst) {
+			struct dst_entry *dst = sk->sk_rx_dst;
+			if (dst->ops->check(dst, 0) == NULL) {
+				dst_release(dst);
+				sk->sk_rx_dst = NULL;
+			}
+		}
+		if (unlikely(sk->sk_rx_dst == NULL)) {
+			struct inet_sock *icsk = inet_sk(sk);
+			struct rtable *rt = skb_rtable(skb);
+
+			sk->sk_rx_dst = dst_clone(&rt->dst);
+			icsk->rx_dst_ifindex = inet_iif(skb);
+		}
 		if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) {
 			rsk = sk;
 			goto reset;
@@ -1700,14 +1714,12 @@ void tcp_v4_early_demux(struct sk_buff *skb)
 		skb->destructor = sock_edemux;
 		if (sk->sk_state != TCP_TIME_WAIT) {
 			struct dst_entry *dst = sk->sk_rx_dst;
+			struct inet_sock *icsk = inet_sk(sk);
 			if (dst)
 				dst = dst_check(dst, 0);
-			if (dst) {
-				struct rtable *rt = (struct rtable *) dst;
-
-				if (rt->rt_iif == dev->ifindex)
-					skb_dst_set_noref(skb, dst);
-			}
+			if (dst &&
+			    icsk->rx_dst_ifindex == dev->ifindex)
+				skb_dst_set_noref(skb, dst);
 		}
 	}
 }
diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index 36fec422740..44f405cb9aa 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -143,7 +143,7 @@ static int route4_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 	if (head == NULL)
 		goto old_method;
 
-	iif = ((struct rtable *)dst)->rt_iif;
+	iif = inet_iif(skb);
 
 	h = route4_fastmap_hash(id, iif);
 	if (id == head->fastmap[h].id &&
diff --git a/net/sched/em_meta.c b/net/sched/em_meta.c
index 4790c696cbc..4ab6e332557 100644
--- a/net/sched/em_meta.c
+++ b/net/sched/em_meta.c
@@ -264,7 +264,7 @@ META_COLLECTOR(int_rtiif)
 	if (unlikely(skb_rtable(skb) == NULL))
 		*err = -1;
 	else
-		dst->value = skb_rtable(skb)->rt_iif;
+		dst->value = inet_iif(skb);
 }
 
 /**************************************************************************
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 9c90811d113..1f89c4e6964 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -568,7 +568,7 @@ static void sctp_v4_get_saddr(struct sctp_sock *sk,
 /* What interface did this skb arrive on? */
 static int sctp_v4_skb_iif(const struct sk_buff *skb)
 {
-	return skb_rtable(skb)->rt_iif;
+	return inet_iif(skb);
 }
 
 /* Was this packet marked by Explicit Congestion Notification? */