[GitHub] [incubator-nuttx] yamt commented on a change in pull request #4069: net/socket: add SO_RCVBUF support

[GitBox <gi...@apache.org>]

yamt commented on a change in pull request #4069:
URL: https://github.com/apache/incubator-nuttx/pull/4069#discussion_r663800441



##########
File path: net/udp/udp_callback.c
##########
@@ -83,6 +83,14 @@ static uint16_t udp_datahandler(FAR struct net_driver_s *dev,
   FAR void  *src_addr;
   uint8_t src_addr_size;
 
+#if CONFIG_NET_RECV_BUFSIZE > 0
+  while (iob_get_queue_size(&conn->readahead) > conn->rcvbufs)
+    {
+      iob = iob_remove_queue(&conn->readahead);
+      iob_free_chain(iob, IOBUSER_NET_UDP_READAHEAD);
+    }
+#endif

Review comment:
       does this mean to drop older packets first? why?

##########
File path: net/tcp/tcp_recvwindow.c
##########
@@ -181,6 +181,29 @@ uint16_t tcp_get_recvwindow(FAR struct net_driver_s *dev,
       recvwndo = tailroom;
     }
 
+#if CONFIG_NET_RECV_BUFSIZE > 0
+  /* Finally, check the receive buffer size further to avoid receive
+   * window out of desire.
+   */

Review comment:
       i guess than conn->readahead == NULL case should be treated as io_pktlen == 0.
   
   that is,
   ```
   queued_bytes = FIONREAD equivalent;
   sbleft = max(conn->rcv_bufs - queued_bytes, 0);
   recvwndo = min(recvwndo, sbleft);
   ```




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