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>

1 files changed, 7 insertions, 5 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 21e22a00481a..b52934f5334e 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -825,7 +825,8 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
                               struct request_sock *req,
                               struct request_values *rvp,
-                              u16 queue_mapping)
+                              u16 queue_mapping,
+                              bool nocache)
 {
         const struct inet_request_sock *ireq = inet_rsk(req);
         struct flowi4 fl4;
@@ -833,7 +834,7 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
         struct sk_buff * skb;
 
         /* First, grab a route. */
-        if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
+        if (!dst && (dst = inet_csk_route_req(sk, &fl4, req, nocache)) == NULL)
                 return -1;
 
         skb = tcp_make_synack(sk, dst, req, rvp);
@@ -855,7 +856,7 @@ static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req,
                               struct request_values *rvp)
 {
         TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
-        return tcp_v4_send_synack(sk, NULL, req, rvp, 0);
+        return tcp_v4_send_synack(sk, NULL, req, rvp, 0, false);
 }
 
 /*
@@ -1388,7 +1389,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
                  */
                 if (tmp_opt.saw_tstamp &&
                     tcp_death_row.sysctl_tw_recycle &&
-                    (dst = inet_csk_route_req(sk, &fl4, req)) != NULL &&
+                    (dst = inet_csk_route_req(sk, &fl4, req, want_cookie)) != NULL &&
                     fl4.daddr == saddr &&
                     (peer = rt_get_peer((struct rtable *)dst, fl4.daddr)) != NULL) {
                         inet_peer_refcheck(peer);
@@ -1424,7 +1425,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 
         if (tcp_v4_send_synack(sk, dst, req,
                                (struct request_values *)&tmp_ext,
-                               skb_get_queue_mapping(skb)) ||
+                               skb_get_queue_mapping(skb),
+                               want_cookie) ||
             want_cookie)
                 goto drop_and_free;