Fix race condition bug in poll() for backlogged connections

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2032 42af7a65-404d-4744-a932-0658087f49c3

2 files changed, 25 insertions, 0 deletions

diff --git a/nuttx/net/net_poll.c b/nuttx/net/net_poll.c
index fac6186c4..0c5e5c75d 100644
--- a/nuttx/net/net_poll.c
+++ b/nuttx/net/net_poll.c
@@ -201,9 +201,15 @@ static inline int net_pollsetup(FAR struct socket *psock, struct pollfd *fds)
 
   fds->priv    = (FAR void *)cb;
 
+#ifdef CONFIG_NET_TCPBACKLOG
+  /* Check for read data or backlogged connection availability now */
+
+  if (!sq_empty(&conn->readahead) || uip_backlogavailable(conn))
+#else
   /* Check for read data availability now */
 
   if (!sq_empty(&conn->readahead))
+#endif
     {
       fds->revents = fds->events & POLLIN;
       if (fds->revents != 0)
diff --git a/nuttx/net/uip/uip_tcpbacklog.c b/nuttx/net/uip/uip_tcpbacklog.c
index 8e6d1fb90..d97acde9c 100644
--- a/nuttx/net/uip/uip_tcpbacklog.c
+++ b/nuttx/net/uip/uip_tcpbacklog.c
@@ -265,6 +265,25 @@ int uip_backlogadd(FAR struct uip_conn *conn, FAR struct uip_conn *blconn)
  * Function: uip_backlogremove
  *
  * Description:
+ *  Called from poll().  Before waiting for a new connection, poll will
+ *  call this API to see if there are pending connections in the backlog.
+ *
+ * Assumptions:
+ *   Called from normal user code, but with interrupts disabled,
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_POLL
+boolean uip_backlogavailable(FAR struct uip_conn *conn)
+{
+  return (conn && conn->backlog && !sq_empty(&conn->backlog->bl_pending));
+}
+#endif
+
+/****************************************************************************
+ * Function: uip_backlogremove
+ *
+ * Description:
  *  Called from accept().  Before waiting for a new connection, accept will
  *  call this API to see if there are pending connections in the backlog.
  *