[TCP]: TCP_DEFER_ACCEPT updates - dont retxmt synack

a socket in LISTEN that had completed its 3 way handshake, but not notified
userspace because of SO_DEFER_ACCEPT, would retransmit the already
acked syn-ack during the time it was waiting for the first data byte
from the peer.

Signed-off-by: Patrick McManus <mcmanus@ducksong.com>
Acked-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index f24c7d534081..8a45be988709 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -461,8 +461,9 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
                 reqp=&lopt->syn_table[i];
                 while ((req = *reqp) != NULL) {
                         if (time_after_eq(now, req->expires)) {
-                                if ((req->retrans < (inet_rsk(req)->acked ? max_retries : thresh))
-                                    && !req->rsk_ops->rtx_syn_ack(parent, req)) {
+                                if ((req->retrans < (inet_rsk(req)->acked ? max_retries : thresh)) &&
+                                    (inet_rsk(req)->acked ||
+                                     !req->rsk_ops->rtx_syn_ack(parent, req))) {
                                         unsigned long timeo;
 
                                         if (req->retrans++ == 0)