netdev/upper: Delay replied packets to prevent TX quota become negated

When our netstack is replying packets when processing RX, the replied
packets will be sent without considering of TX quota because we don't
want to drop them. Now we may delay them by pushing them to a queue and
send them later, which can always keep quota working.

Signed-off-by: Zhe Weng <[email protected]>

drivers/net/netdev_upperhalf.c

@@ -73,6 +73,12 @@ struct netdev_upperhalf_s
 #else
   struct work_s work;
 #endif
+
+  /* TX queue for re-queueing replies */
+
+#if CONFIG_IOB_NCHAINS > 0
+  struct iob_queue_s txq;
+#endif
 };
 
 /****************************************************************************
@@ -279,7 +285,7 @@ static inline bool netdev_upper_can_tx(FAR struct netdev_upperhalf_s *upper)
  *
  * Returned Value:
  *   Negated errno value - Error number that occurs.
- *   OK                  - Driver can send more, continue the poll.
+ *   NETDEV_TX_CONTINUE  - Driver can send more, continue the poll.
  *
  * Assumptions:
  *   Called with the network locked.
@@ -329,6 +335,44 @@ static int netdev_upper_txpoll(FAR struct net_driver_s *dev)
   return NETDEV_TX_CONTINUE;
 }
 
+/****************************************************************************
+ * Name: netdev_upper_tx
+ *
+ * Description:
+ *   Do the actual transmission of packets, including pre-queued packets and
+ *   packets from the network stack.
+ *
+ * Input Parameters:
+ *   dev - Reference to the NuttX driver state structure
+ *
+ * Returned Value:
+ *   Negated errno value - Error number that occurs.
+ *   NETDEV_TX_CONTINUE  - Driver can send more, continue the poll.
+ *
+ * Assumptions:
+ *   Called with the network locked.
+ *
+ ****************************************************************************/
+
+static int netdev_upper_tx(FAR struct net_driver_s *dev)
+{
+#if CONFIG_IOB_NCHAINS > 0
+  FAR struct netdev_upperhalf_s *upper = dev->d_private;
+
+  if (!IOB_QEMPTY(&upper->txq))
+    {
+      /* Put the packet back to the device */
+
+      netdev_iob_replace(dev, iob_remove_queue(&upper->txq));
+      return netdev_upper_txpoll(dev);
+    }
+#endif
+
+  /* No more TX packets in queue, poll the net stack to get more packets */
+
+  return devif_poll(dev, netdev_upper_txpoll);
+}
+
 /****************************************************************************
  * Name: netdev_upper_txavail_work
  *
@@ -353,10 +397,62 @@ static void netdev_upper_txavail_work(FAR struct netdev_upperhalf_s *upper)
     {
       DEBUGASSERT(dev->d_buf == NULL); /* Make sure: IOB only. */
       while (netdev_upper_can_tx(upper) &&
-             devif_poll(dev, netdev_upper_txpoll) == NETDEV_TX_CONTINUE);
+             netdev_upper_tx(dev) == NETDEV_TX_CONTINUE);
     }
 }
 
+/****************************************************************************
+ * Name: netdev_upper_queue_tx
+ *
+ * Description:
+ *   Queue a TX packet to the upper half for sending later.
+ *
+ * Input Parameters:
+ *   dev - Reference to the NuttX driver state structure
+ *
+ * Assumptions:
+ *   Called with the network locked.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_NET_LOOPBACK) || defined(CONFIG_NET_ETHERNET) || \
+    defined(CONFIG_DRIVERS_IEEE80211) || defined(CONFIG_NET_MBIM)
+static void netdev_upper_queue_tx(FAR struct net_driver_s *dev)
+{
+#if CONFIG_IOB_NCHAINS > 0
+  FAR struct netdev_upperhalf_s *upper = dev->d_private;
+  int ret;
+
+  if ((ret = iob_tryadd_queue(dev->d_iob, &upper->txq)) >= 0)
+    {
+      netdev_iob_clear(dev);
+    }
+  else
+    {
+      nwarn("WARNING: Failed to queue TX packet, dropping: %d\n", ret);
+    }
+#else
+  /* Fall back to send the packet directly if we don't have IOB queue. */
+
+  netdev_upper_txpoll(dev);
+#endif
+}
+#endif
+
+/****************************************************************************
+ * Name: eth_input
+ *
+ * Description:
+ *   Handle L2 packet input.
+ *
+ * Input Parameters:
+ *   dev - Reference to the NuttX network driver state structure
+ *
+ * Assumptions:
+ *   Called with the network locked.
+ *
+ ****************************************************************************/
+
 #if defined(CONFIG_NET_LOOPBACK) || defined(CONFIG_NET_ETHERNET) || \
     defined(CONFIG_DRIVERS_IEEE80211)
 static void eth_input(FAR struct net_driver_s *dev)
@@ -432,9 +528,11 @@ static void eth_input(FAR struct net_driver_s *dev)
 
   if (dev->d_len > 0)
     {
-      /* And send the packet */
+      /* And queue the packet for sending later.
+       * Note: RX is tried before TX, so we don't need to call txavail here.
+       */
 
-      netdev_upper_txpoll(dev);
+      netdev_upper_queue_tx(dev);
     }
 }
 #endif
@@ -495,9 +593,11 @@ static void ip_input(FAR struct net_driver_s *dev)
 
   if (dev->d_len > 0)
     {
-      /* And send the packet */
+      /* And queue the packet for sending later.
+       * Note: RX is tried before TX, so we don't need to call txavail here.
+       */
 
-      netdev_upper_txpoll(dev);
+      netdev_upper_queue_tx(dev);
     }
 }
 #endif
@@ -1149,6 +1249,10 @@ int netdev_lower_unregister(FAR struct netdev_lowerhalf_s *dev)
   nxsem_destroy(&upper->sem_exit);
 #endif
 
+#if CONFIG_IOB_NCHAINS > 0
+  iob_free_queue(&upper->txq);
+#endif
+
   kmm_free(upper);
   dev->netdev.d_private = NULL;