4 files changed, 13 insertions, 2 deletions

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 98ca797001a2..5478356ea8c5 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -389,6 +389,7 @@ extern void tcp_enter_loss(struct sock *sk, int how);
 extern void tcp_clear_retrans(struct tcp_sock *tp);
 extern void tcp_update_metrics(struct sock *sk);
 extern void tcp_init_metrics(struct sock *sk);
+extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
 extern void tcp_disable_fack(struct tcp_sock *tp);
 extern void tcp_close(struct sock *sk, long timeout);
 extern void tcp_init_sock(struct sock *sk);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 64568fa21d05..e9312a8f33a1 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1405,7 +1405,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
                          (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
                           (sysctl_max_syn_backlog >> 2)) &&
                          (!peer || !peer->tcp_ts_stamp) &&
-                         (!dst || !dst_metric(dst, RTAX_RTT))) {
+                         !tcp_peer_is_proven(req, dst)) {
                         /* Without syncookies last quarter of
                          * backlog is filled with destinations,
                          * proven to be alive.
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index 2793ecf928d3..9afe703c85cc 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -1,7 +1,9 @@
+#include <linux/module.h>
 #include <linux/cache.h>
 #include <linux/tcp.h>
 
 #include <net/inet_connection_sock.h>
+#include <net/request_sock.h>
 #include <net/sock.h>
 #include <net/dst.h>
 #include <net/tcp.h>
@@ -190,3 +192,11 @@ reset:
                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
         tp->snd_cwnd_stamp = tcp_time_stamp;
 }
+
+bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst)
+{
+        if (!dst)
+                return false;
+        return dst_metric(dst, RTAX_RTT) ? true : false;
+}
+EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 6cc67ed6c2e6..75d179555c28 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1177,7 +1177,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
                          (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
                           (sysctl_max_syn_backlog >> 2)) &&
                          (!peer || !peer->tcp_ts_stamp) &&
-                         (!dst || !dst_metric(dst, RTAX_RTT))) {
+                         !tcp_peer_is_proven(req, dst)) {
                         /* Without syncookies last quarter of
                          * backlog is filled with destinations,
                          * proven to be alive.