tcp: reduce SYN-ACK retrans for TCP_DEFER_ACCEPT

[mv-sheeva.git] / net / ipv4 / inet_connection_sock.c

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 4351ca2cf0b8554eadd258295d44a93455f3e506..537731b3bcb3e5717769588e2f0768bc02ed8570 100644 (file)
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -446,6 +446,28 @@ extern int sysctl_tcp_synack_retries;
 
 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
 
+/* Decide when to expire the request and when to resend SYN-ACK */
+static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
+                                 const int max_retries,
+                                 const u8 rskq_defer_accept,
+                                 int *expire, int *resend)
+{
+       if (!rskq_defer_accept) {
+               *expire = req->retrans >= thresh;
+               *resend = 1;
+               return;
+       }
+       *expire = req->retrans >= thresh &&
+                 (!inet_rsk(req)->acked || req->retrans >= max_retries);
+       /*
+        * Do not resend while waiting for data after ACK,
+        * start to resend on end of deferring period to give
+        * last chance for data or ACK to create established socket.
+        */
+       *resend = !inet_rsk(req)->acked ||
+                 req->retrans >= rskq_defer_accept - 1;
+}
+
 void inet_csk_reqsk_queue_prune(struct sock *parent,
                                const unsigned long interval,
                                const unsigned long timeout,
@@ -501,9 +523,15 @@ 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 < thresh ||
-                                    (inet_rsk(req)->acked && req->retrans < max_retries))
-                                   && !req->rsk_ops->rtx_syn_ack(parent, req)) {
+                               int expire = 0, resend = 0;
+
+                               syn_ack_recalc(req, thresh, max_retries,
+                                              queue->rskq_defer_accept,
+                                              &expire, &resend);
+                               if (!expire &&
+                                   (!resend ||
+                                    !req->rsk_ops->rtx_syn_ack(parent, req) ||
+                                    inet_rsk(req)->acked)) {
                                        unsigned long timeo;
 
                                        if (req->retrans++ == 0)