[TCP]: TCP_DEFER_ACCEPT updates - process as established

Change TCP_DEFER_ACCEPT implementation so that it transitions a
connection to ESTABLISHED after handshake is complete instead of
leaving it in SYN-RECV until some data arrvies. Place connection in
accept queue when first data packet arrives from slow path.

Benefits:
  - established connection is now reset if it never makes it
   to the accept queue

 - diagnostic state of established matches with the packet traces
   showing completed handshake

 - TCP_DEFER_ACCEPT timeouts are expressed in seconds and can now be
   enforced with reasonable accuracy instead of rounding up to next
   exponential back-off of syn-ack retry.

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

1 files changed, 3 insertions, 8 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 8a45be988709..cc1a1859a61b 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -414,8 +414,7 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
         struct inet_connection_sock *icsk = inet_csk(parent);
         struct request_sock_queue *queue = &icsk->icsk_accept_queue;
         struct listen_sock *lopt = queue->listen_opt;
-        int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
-        int thresh = max_retries;
+        int thresh = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
         unsigned long now = jiffies;
         struct request_sock **reqp, *req;
         int i, budget;
@@ -451,9 +450,6 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
                 }
         }
 
-        if (queue->rskq_defer_accept)
-                max_retries = queue->rskq_defer_accept;
-
         budget = 2 * (lopt->nr_table_entries / (timeout / interval));
         i = lopt->clock_hand;
 
@@ -461,9 +457,8 @@ 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)) &&
-                                    (inet_rsk(req)->acked ||
-                                     !req->rsk_ops->rtx_syn_ack(parent, req))) {
+                                if (req->retrans < thresh &&
+                                    !req->rsk_ops->rtx_syn_ack(parent, req)) {
                                         unsigned long timeo;
 
                                         if (req->retrans++ == 0)