tcp: replace dst_confirm with sk_dst_confirm

BugLink: https://bugs.launchpad.net/bugs/1715812

When same struct dst_entry can be used for many different
neighbours we can not use it for pending confirmations.
Use the new sk_dst_confirm() helper to propagate the
indication from received packets to sock_confirm_neigh().
Reported-by: YueHaibing <yuehaibing@huawei.com>
Fixes: 5110effe ("net: Do delayed neigh confirmation.")
Fixes: f2bb4bed ("ipv4: Cache output routes in fib_info nexthops.")
Tested-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(backported from commit c3a2e837)
Signed-off-by: Daniel Axtens <daniel.axtens@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

net/ipv4/tcp_input.c

@@ -3637,11 +3637,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	if (tcp_may_raise_cwnd(sk, flag))
 		tcp_cong_avoid(sk, ack, acked);
 
-	if ((flag & FLAG_FORWARD_PROGRESS) || !(flag & FLAG_NOT_DUP)) {
-		struct dst_entry *dst = __sk_dst_get(sk);
-		if (dst)
-			dst_confirm(dst);
-	}
+	if ((flag & FLAG_FORWARD_PROGRESS) || !(flag & FLAG_NOT_DUP))
+		sk_dst_confirm(sk);
 
 	if (icsk->icsk_pending == ICSK_TIME_RETRANS)
 		tcp_schedule_loss_probe(sk);
@@ -5897,7 +5894,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		break;
 
 	case TCP_FIN_WAIT1: {
-		struct dst_entry *dst;
 		int tmo;
 
 		/* If we enter the TCP_FIN_WAIT1 state and we are a
@@ -5924,9 +5920,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 		tcp_set_state(sk, TCP_FIN_WAIT2);
 		sk->sk_shutdown |= SEND_SHUTDOWN;
 
-		dst = __sk_dst_get(sk);
-		if (dst)
-			dst_confirm(dst);
+		sk_dst_confirm(sk);
 
 		if (!sock_flag(sk, SOCK_DEAD)) {
 			/* Wake up lingering close() */

net/ipv4/tcp_metrics.c

@@ -374,12 +374,10 @@ void tcp_update_metrics(struct sock *sk)
 	u32 val;
 	int m;
 
+	sk_dst_confirm(sk);
 	if (sysctl_tcp_nometrics_save || !dst)
 		return;
 
-	if (dst->flags & DST_HOST)
-		dst_confirm(dst);
-
 	rcu_read_lock();
 	if (icsk->icsk_backoff || !tp->srtt_us) {
 		/* This session failed to estimate rtt. Why?
@@ -492,11 +490,10 @@ void tcp_init_metrics(struct sock *sk)
 	struct tcp_metrics_block *tm;
 	u32 val, crtt = 0; /* cached RTT scaled by 8 */
 
+	sk_dst_confirm(sk);
 	if (!dst)
 		goto reset;
 
-	dst_confirm(dst);
-
 	rcu_read_lock();
 	tm = tcp_get_metrics(sk, dst, true);
 	if (!tm) {

net/ipv4/tcp_output.c

@@ -957,6 +957,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	skb_set_hash_from_sk(skb, sk);
 	atomic_add(skb->truesize, &sk->sk_wmem_alloc);
 
+	skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm);
+
 	/* Build TCP header and checksum it. */
 	th = tcp_hdr(skb);
 	th->source		= inet->inet_sport;