net/tcp: Same change to tcp_send_buffered.c probably also applies to tcp_send_unbuffered.c.

configs/pizero/README.txt

@@ -13,10 +13,21 @@ STATUS
     will not build to completion.  Missing logic includes:
 
     - GPIO support,
-    - Peripheral clocking support,
     - System timer initialization, and
     - Serial driver.
 
+  2017-10-19:  Much of that logic is in place but there are a few things
+    still missing.
+
+    - Mini-UART Baud divisor calculation,
+    - Start-up logic.  My understand from what I have read on the internet
+      is the PiZero OS starts up in hypervisor mode with the MMU and I- and
+      D-Caches enabled.  This probaby means that the standard, classic ARM
+      startup logic at at arch/arm/src/arm/up_head.S will need to be replaced
+      with some custom logic.
+
+    No testing has yet been performed.
+
 Basic Setup
 ===========
 

net/tcp/tcp_send_unbuffered.c

@@ -398,9 +398,18 @@ static uint16_t tcpsend_eventhandler(FAR struct net_driver_s *dev,
     {
       ninfo("Lost connection\n");
 
-      /* Report not connected */
+      /* We could get here recursively through the callback actions of
+       * tcp_lost_connection().  So don't repeat that action if we have
+       * already been disconnected.
+       */
+
+      if (_SS_ISCONNECTED(psock->s_flags))
+         {
+           /* Report not connected */
+
+           tcp_lost_connection(pstate->snd_sock, pstate->snd_cb, flags);
+         }
 
-      tcp_lost_connection(pstate->snd_sock, pstate->snd_cb, flags);
       pstate->snd_sent = -ENOTCONN;
       goto end_wait;
     }