tcp: tcp_syn_flood_action() can be static

After commit 1fb6f159 ("tcp: add tcp_conn_request"),
tcp_syn_flood_action() is no longer used from IPv6.

We can make it static, by moving it above tcp_conn_request()
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reviewed-by: NOctavian Purdila <octavian.purdila@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -529,8 +529,6 @@ int tcp_write_wakeup(struct sock *);
 void tcp_send_fin(struct sock *sk);
 void tcp_send_active_reset(struct sock *sk, gfp_t priority);
 int tcp_send_synack(struct sock *);
-bool tcp_syn_flood_action(struct sock *sk, const struct sk_buff *skb,
-			  const char *proto);
 void tcp_push_one(struct sock *, unsigned int mss_now);
 void tcp_send_ack(struct sock *sk);
 void tcp_send_delayed_ack(struct sock *sk);

net/ipv4/tcp_input.c

@@ -5987,6 +5987,35 @@ struct request_sock *inet_reqsk_alloc(const struct request_sock_ops *ops,
 }
 EXPORT_SYMBOL(inet_reqsk_alloc);
 
+/*
+ * Return true if a syncookie should be sent
+ */
+static bool tcp_syn_flood_action(struct sock *sk,
+				 const struct sk_buff *skb,
+				 const char *proto)
+{
+	const char *msg = "Dropping request";
+	bool want_cookie = false;
+	struct listen_sock *lopt;
+
+#ifdef CONFIG_SYN_COOKIES
+	if (sysctl_tcp_syncookies) {
+		msg = "Sending cookies";
+		want_cookie = true;
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDOCOOKIES);
+	} else
+#endif
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
+
+	lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;
+	if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) {
+		lopt->synflood_warned = 1;
+		pr_info("%s: Possible SYN flooding on port %d. %s.  Check SNMP counters.\n",
+			proto, ntohs(tcp_hdr(skb)->dest), msg);
+	}
+	return want_cookie;
+}
+
 int tcp_conn_request(struct request_sock_ops *rsk_ops,
 		     const struct tcp_request_sock_ops *af_ops,
 		     struct sock *sk, struct sk_buff *skb)

net/ipv4/tcp_ipv4.c

@@ -856,35 +856,6 @@ static void tcp_v4_reqsk_destructor(struct request_sock *req)
 	kfree(inet_rsk(req)->opt);
 }
 
-/*
- * Return true if a syncookie should be sent
- */
-bool tcp_syn_flood_action(struct sock *sk,
-			 const struct sk_buff *skb,
-			 const char *proto)
-{
-	const char *msg = "Dropping request";
-	bool want_cookie = false;
-	struct listen_sock *lopt;
-
-#ifdef CONFIG_SYN_COOKIES
-	if (sysctl_tcp_syncookies) {
-		msg = "Sending cookies";
-		want_cookie = true;
-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDOCOOKIES);
-	} else
-#endif
-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPREQQFULLDROP);
-
-	lopt = inet_csk(sk)->icsk_accept_queue.listen_opt;
-	if (!lopt->synflood_warned && sysctl_tcp_syncookies != 2) {
-		lopt->synflood_warned = 1;
-		pr_info("%s: Possible SYN flooding on port %d. %s.  Check SNMP counters.\n",
-			proto, ntohs(tcp_hdr(skb)->dest), msg);
-	}
-	return want_cookie;
-}
-EXPORT_SYMBOL(tcp_syn_flood_action);
 
 #ifdef CONFIG_TCP_MD5SIG
 /*