soreuseport: Resolve merge conflict for v4/v6 ordering fix

d894ba18 ("soreuseport: fix ordering for mixed v4/v6 sockets")
was merged as a bug fix to the net tree.  Two conflicting changes
were committed to net-next before the above fix was merged back to
net-next:
ca065d0c ("udp: no longer use SLAB_DESTROY_BY_RCU")
3b24d854 ("tcp/dccp: do not touch listener sk_refcnt under synflood")

These changes switched the datastructure used for TCP and UDP sockets
from hlist_nulls to hlist.  This patch applies the necessary parts
of the net tree fix to net-next which were not automatic as part of the
merge.

Fixes: 1602f49b ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net")
Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -630,7 +630,11 @@ static inline void sk_add_node(struct sock *sk, struct hlist_head *list)
 static inline void sk_add_node_rcu(struct sock *sk, struct hlist_head *list)
 {
 	sock_hold(sk);
-	hlist_add_head_rcu(&sk->sk_node, list);
+	if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
+	    sk->sk_family == AF_INET6)
+		hlist_add_tail_rcu(&sk->sk_node, list);
+	else
+		hlist_add_head_rcu(&sk->sk_node, list);
 }
 
 static inline void __sk_nulls_add_node_rcu(struct sock *sk, struct hlist_nulls_head *list)

net/ipv4/inet_hashtables.c

@@ -479,7 +479,11 @@ int __inet_hash(struct sock *sk, struct sock *osk,
 		if (err)
 			goto unlock;
 	}
-	hlist_add_head_rcu(&sk->sk_node, &ilb->head);
+	if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
+		sk->sk_family == AF_INET6)
+		hlist_add_tail_rcu(&sk->sk_node, &ilb->head);
+	else
+		hlist_add_head_rcu(&sk->sk_node, &ilb->head);
 	sock_set_flag(sk, SOCK_RCU_FREE);
 	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 unlock: