IP forwarding: A few fixes from early testing; In TUN driver, do all polling on worker thread. Otherwise, the stack gets very deep.

configs/sim/ipforward/defconfig

@@ -303,7 +303,7 @@ CONFIG_SCHED_LPWORK=y
 CONFIG_SCHED_LPNTHREADS=1
 CONFIG_SCHED_LPWORKPRIORITY=140
 CONFIG_SCHED_LPWORKPERIOD=50000
-CONFIG_SCHED_LPWORKSTACKSIZE=2048
+CONFIG_SCHED_LPWORKSTACKSIZE=8192
 
 #
 # Stack and heap information
@@ -376,9 +376,26 @@ CONFIG_DEV_LOOP=y
 # CONFIG_MODEM is not set
 # CONFIG_MTD is not set
 # CONFIG_EEPROM is not set
-# CONFIG_NETDEVICES is not set
+CONFIG_NETDEVICES=y
+
+#
+# General Ethernet MAC Driver Options
+#
+# CONFIG_NETDEV_LOOPBACK is not set
+# CONFIG_NETDEV_TELNET is not set
+CONFIG_NETDEV_MULTINIC=y
 CONFIG_ARCH_HAVE_NETDEV_STATISTICS=y
+# CONFIG_NETDEV_LATEINIT is not set
+# CONFIG_NET_DUMPPACKET is not set
+
+#
+# External Ethernet MAC Device Support
+#
+# CONFIG_NET_DM90x0 is not set
+# CONFIG_ENC28J60 is not set
+# CONFIG_ENCX24J600 is not set
 # CONFIG_NET_SLIP is not set
+# CONFIG_NET_FTMAC100 is not set
 # CONFIG_PIPES is not set
 # CONFIG_PM is not set
 # CONFIG_POWER is not set
@@ -480,6 +497,8 @@ CONFIG_TUN_LPWORK=y
 CONFIG_NET_IPv6=y
 CONFIG_NET_IPv6_NCONF_ENTRIES=4
 CONFIG_NET_IPFORWARD=y
+# CONFIG_NET_IPFORWARD_BROADCAST is not set
+CONFIG_NET_IPFORWARD_NSTRUCT=4
 
 #
 # Socket Support
@@ -790,7 +809,7 @@ CONFIG_BUILTIN_PROXY_STACKSIZE=1024
 # CONFIG_EXAMPLES_IGMP is not set
 CONFIG_EXAMPLES_IPFORWARD=y
 CONFIG_EXAMPLES_IPFORWARD_PRIORITY=100
-CONFIG_EXAMPLES_IPFORWARD_STACKSIZE=2048
+CONFIG_EXAMPLES_IPFORWARD_STACKSIZE=8192
 # CONFIG_EXAMPLES_JSON is not set
 # CONFIG_EXAMPLES_MEDIA is not set
 # CONFIG_EXAMPLES_MM is not set

drivers/net/tun.c

@@ -684,7 +684,7 @@ static int tun_ifdown(struct net_driver_s *dev)
 }
 
 /****************************************************************************
- * Name: tun_txavail
+ * Name: tun_txavail_work
  *
  * Description:
  *   Driver callback invoked when new TX data is available.  This is a
@@ -702,9 +702,9 @@ static int tun_ifdown(struct net_driver_s *dev)
  *
  ****************************************************************************/
 
-static int tun_txavail(struct net_driver_s *dev)
+static void tun_txavail_work(FAR void *arg)
 {
-  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)arg;
 
   tun_lock(priv);
 
@@ -713,11 +713,10 @@ static int tun_txavail(struct net_driver_s *dev)
   if (priv->read_d_len != 0 || priv->write_d_len != 0)
     {
       tun_unlock(priv);
-      return OK;
+      return;
     }
 
   net_lock();
-
   if (priv->bifup)
     {
       /* Poll the network for new XMIT data */
@@ -728,6 +727,37 @@ static int tun_txavail(struct net_driver_s *dev)
 
   net_unlock();
   tun_unlock(priv);
+}
+
+/****************************************************************************
+ * Name: tun_txavail
+ *
+ * Description:
+ *   Driver callback invoked when new TX data is available.  This is a
+ *   stimulus perform an out-of-cycle poll and, thereby, reduce the TX
+ *   latency.
+ *
+ * Parameters:
+ *   dev - Reference to the NuttX driver state structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   Called from the network stack with the network locked.
+ *
+ ****************************************************************************/
+
+static int tun_txavail(struct net_driver_s *dev)
+{
+  FAR struct tun_device_s *priv = (FAR struct tun_device_s *)dev->d_private;
+
+  /* Schedule to perform the TX poll on the worker thread. */
+
+  if (work_available(&priv->work))
+    {
+      work_queue(TUNWORK, &priv->work, tun_txavail_work, priv, 0);
+    }
 
   return OK;
 }

net/devif/ipv4_forward.c

@@ -91,7 +91,7 @@ static int ipv4_hdrsize(FAR struct ipv4_hdr_s *ipv4)
     case IP_PROTO_TCP:
       {
         FAR struct tcp_hdr_s *tcp =
-          (FAR struct tcp_hdr_s *)((FAR uintptr_t *)ipv4 + IPv4_HDRLEN);
+          (FAR struct tcp_hdr_s *)((FAR uint8_t *)ipv4 + IPv4_HDRLEN);
         unsigned int tcpsize;
 
         /* The TCP header length is encoded in the top 4 bits of the

net/devif/ipv6_forward.c

@@ -97,7 +97,7 @@ static int ipv6_hdrsize(FAR struct ipv6_hdr_s *ipv6)
     case IP_PROTO_TCP:
       {
         FAR struct tcp_hdr_s *tcp =
-          (FAR struct tcp_hdr_s *)((FAR uintptr_t *)ipv6 + IPv6_HDRLEN);
+          (FAR struct tcp_hdr_s *)((FAR uint8_t *)ipv6 + IPv6_HDRLEN);
         unsigned int tcpsize;
 
         /* The TCP header length is encoded in the top 4 bits of the
@@ -337,7 +337,7 @@ static int ipv6_packet_conversion(FAR struct net_driver_s *dev,
   return ret;
 }
 #else
-#  define ipv6_packet_conversion(dev, ipv6) (PACKET_NOT_FORWARDED)
+#  define ipv6_packet_conversion(dev, fwddev, ipv6) (PACKET_NOT_FORWARDED)
 #endif /* CONFIG_NET_6LOWPAN */
 
 /****************************************************************************

net/netdev/netdev_txnotify.c

@@ -167,7 +167,7 @@ void netdev_ipv6_txnotify(FAR const net_ipv6addr_t ripaddr)
 
 void netdev_txnotify_dev(FAR struct net_driver_s *dev)
 {
-  if (dev && dev->d_txavail)
+  if (dev != NULL && dev->d_txavail != NULL)
     {
       /* Notify the device driver that new TX data is available. */