ipv4: tcp: dont cache output dst for syncookies

Don't cache output dst for syncookies, as this adds pressure on IP route
cache and rcu subsystem for no gain.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Hans Schillstrom <hans.schillstrom@ericsson.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 07f5579..3eb76b5 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -504,7 +504,7 @@
 	struct dst_entry *dst;
 	struct flowi4 fl4;
 
-	dst = inet_csk_route_req(sk, &fl4, req);
+	dst = inet_csk_route_req(sk, &fl4, req, false);
 	if (dst == NULL)
 		goto out;