Networking: A placeholder for some missing logic in the previous change related to monitoring network status for dup'ed sockets. If one of the dup'ed socket's is closed, then network monitor resources associated with that one socket must be recovered. Also, in the event that socket is being used on one thread, but then closed on another, any threads waiting for events from the socket should be informed of the closure. That latter requirement is not implemented because current data structures do not support it.

net/inet/inet_close.c

@@ -506,7 +506,7 @@ int inet_close(FAR struct socket *psock)
                   return ret;
                 }
 
-              /* Stop the network monitor */
+              /* Stop the network monitor for all sockets */
 
               tcp_stop_monitor(conn, TCP_CLOSE);
             }
@@ -515,6 +515,10 @@ int inet_close(FAR struct socket *psock)
               /* No.. Just decrement the reference count */
 
               conn->crefs--;
+
+              /* Stop monitor for this socket only */
+
+              tcp_close_monitor(psock);
             }
 #else
         nwarn("WARNING: SOCK_STREAM support is not available in this configuration\n");

net/tcp/tcp.h

@@ -575,6 +575,29 @@ int tcp_start_monitor(FAR struct socket *psock);
 
 void tcp_stop_monitor(FAR struct tcp_conn_s *conn, uint16_t flags);
 
+/****************************************************************************
+ * Name: tcp_close_monitor
+ *
+ * Description:
+ *   One socket in a group of dup'ed sockets has been closed.  We need to
+ *   selectively terminate just those things that are waiting of events
+ *   from this specific socket.  And also recover any resources that are
+ *   committed to monitoring this socket.
+ *
+ * Input Parameters:
+ *   psock - The TCP socket structure that is closed
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   The caller holds the network lock (if not, it will be locked momentarily
+ *   by this function).
+ *
+ ****************************************************************************/
+
+void tcp_close_monitor(FAR struct socket *psock);
+
 /****************************************************************************
  * Name: tcp_lost_connection
  *

net/tcp/tcp_monitor.c

@@ -327,6 +327,75 @@ void tcp_stop_monitor(FAR struct tcp_conn_s *conn, uint16_t flags)
   tcp_shutdown_monitor(conn, flags);
 }
 
+/****************************************************************************
+ * Name: tcp_close_monitor
+ *
+ * Description:
+ *   One socket in a group of dup'ed sockets has been closed.  We need to
+ *   selectively terminate just those things that are waiting of events
+ *   from this specific socket.  And also recover any resources that are
+ *   committed to monitoring this socket.
+ *
+ * Input Parameters:
+ *   psock - The TCP socket structure that is closed
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   The caller holds the network lock (if not, it will be locked momentarily
+ *   by this function).
+ *
+ ****************************************************************************/
+
+void tcp_close_monitor(FAR struct socket *psock)
+{
+  FAR struct tcp_conn_s *conn;
+  FAR struct devif_callback_s *cb;
+
+  DEBUGASSERT(psock != NULL && psock->s_conn != NULL);
+  conn = (FAR struct tcp_conn_s *)psock->s_conn;
+
+  /* Find and free the the connection event callback */
+
+  net_lock();
+  for (cb = conn->connevents;
+       cb != NULL && cb->priv != (FAR void *)psock;
+       cb = cb->nxtconn)
+    {
+    }
+
+  if (cb != NULL)
+    {
+      devif_conn_callback_free(conn->dev, cb, &conn->connevents);
+    }
+
+  /* Make sure that this socket is explicitly marked as closed */
+
+  tcp_close_connection(psock, TCP_CLOSE);
+
+  /* Now notify any sockets waiting for events from this particular sockets.
+   * Other dup'ed sockets sharing the same connection must not be effected.
+   */
+
+  /* REVISIT:  The following logic won't work:  There is no way to compare
+   * psocks to check for a match.  This could only be an issue if the same
+   * socket were being used on one thread, but then closed on another.
+   * Some redesign would be required to find only those event handlers that 
+   * re waiting specifically for this socket (vs. a dup of this this socket)
+   */
+
+#if 0
+  for (cb = conn->list; cb != NULL; cb = cb->nxtconn)
+    {
+      if (cb->event != NULL && (cb->flags & TCP_CLOSE) != 0)
+        {
+          (void)cb->event(conn->dev, conn, cb->priv, TCP_CLOSE);
+        }
+    }
+#endif
+}
+
 /****************************************************************************
  * Name: tcp_lost_connection
  *
@@ -337,7 +406,7 @@ void tcp_stop_monitor(FAR struct tcp_conn_s *conn, uint16_t flags)
  *   the "interrupt handler".
  *
  * Parameters:
- *   psock - The TCP socket structure associated.
+ *   psock - The TCP socket structure whose connection was lost.
  *   cb    - devif callback structure
  *   flags - Set of connection events events
  *
@@ -363,13 +432,13 @@ void tcp_lost_connection(FAR struct socket *psock,
   cb->priv  = NULL;
   cb->event = NULL;
 
-  /* Make sure that this socket is explicitly marked.  It may not bet a
+  /* Make sure that this socket is explicitly marked.  It may not get a
    * callback due to the above nullification.
    */
 
   tcp_close_connection(psock, flags);
 
-  /* Then stop the network monitor */
+  /* Then stop the network monitor for all sockets. */
 
   tcp_shutdown_monitor((FAR struct tcp_conn_s *)psock->s_conn, flags);
 }