[PATCH net-next] tcp: Fix build break when CONFIG_IPV6=n

[Saeed Mahameed <saeed@kernel.org>]

From: Saeed Mahameed <saeedm@nvidia.com>

The cited commit caused the following build break when CONFIG_IPV6 was
disabled

net/ipv4/tcp_input.c: In function ‘tcp_syn_flood_action’:
include/net/sock.h:387:37: error: ‘const struct sock_common’ has no member named ‘skc_v6_rcv_saddr’; did you mean ‘skc_rcv_saddr’?

Fix by using inet6_rcv_saddr() macro which handles this situation
nicely.

Fixes: d9282e48c608 ("tcp: Add listening address to SYN flood message")
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
CC: Matthieu Baerts <matthieu.baerts@tessares.net>
CC: Jamie Bainbridge <jamie.bainbridge@gmail.com>
---
 net/ipv4/tcp_input.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0ae291e53eab..f8548a57a17a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6843,9 +6843,9 @@ static bool tcp_syn_flood_action(const struct sock *sk, const char *proto)
 
 	if (!READ_ONCE(queue->synflood_warned) && syncookies != 2 &&
 	    xchg(&queue->synflood_warned, 1) == 0) {
-		if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6) {
+		if (sk->sk_family == AF_INET6) {
 			net_info_ratelimited("%s: Possible SYN flooding on port [%pI6c]:%u. %s.\n",
-					proto, &sk->sk_v6_rcv_saddr,
+					proto, inet6_rcv_saddr(sk),
 					sk->sk_num, msg);
 		} else {
 			net_info_ratelimited("%s: Possible SYN flooding on port %pI4:%u. %s.\n",
-- 
2.38.1