tcp: req app deq notification on fifo full

If fifo full, default to requesting an app deq notification and forcing
an ack (window update) if zero rcv window sent is still active.

Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Iade7e1722503da149c62c465c472edbb0a5599f7

1 files changed, 22 insertions, 0 deletions

diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index e447fac00b5..a6c1e216c20 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -1272,6 +1272,27 @@ tcp_session_flush_data (transport_connection_t * tconn)
   tc->psh_seq = tc->snd_una + transport_max_tx_dequeue (tconn) - 1;
 }
 
+static int
+tcp_session_app_rx_evt (transport_connection_t *conn)
+{
+  tcp_connection_t *tc = (tcp_connection_t *) conn;
+  u32 min_free, lo = 4 << 10, hi = 128 << 10;
+
+  if (!(tc->flags & TCP_CONN_ZERO_RWND_SENT))
+    return 0;
+
+  min_free = clib_clamp (transport_rx_fifo_size (conn) >> 3, lo, hi);
+  if (transport_max_rx_enqueue (conn) < min_free)
+    {
+      transport_rx_fifo_req_deq_ntf (conn);
+      return 0;
+    }
+
+  tcp_send_ack (tc);
+
+  return 0;
+}
+
 /* *INDENT-OFF* */
 const static transport_proto_vft_t tcp_proto = {
   .enable = vnet_tcp_enable_disable,
@@ -1291,6 +1312,7 @@ const static transport_proto_vft_t tcp_proto = {
   .update_time = tcp_update_time,
   .flush_data = tcp_session_flush_data,
   .custom_tx = tcp_session_custom_tx,
+  .app_rx_evt = tcp_session_app_rx_evt,
   .format_connection = format_tcp_session,
   .format_listener = format_tcp_listener_session,
   .format_half_open = format_tcp_half_open_session,