From 8688bd0593d656d75acc56ab2418a6fc8eb8e6bf Mon Sep 17 00:00:00 2001
From: xueyunfei <xueyunfei@espressif.com>
Date: Thu, 14 May 2020 15:18:39 +0800
Subject: [PATCH 1/2] add LINGER to menuconfig

---
 components/lwip/Kconfig                       | 11 +++++++++++
 components/lwip/port/esp32/include/lwipopts.h |  5 +++++
 2 files changed, 16 insertions(+)

diff --git a/components/lwip/Kconfig b/components/lwip/Kconfig
index e2f289b643..d6f2aa13fe 100644
--- a/components/lwip/Kconfig
+++ b/components/lwip/Kconfig
@@ -63,6 +63,17 @@ menu "LWIP"
             will be redirected to lwip_select(), therefore, select can be used
             for sockets only.
 
+    config LWIP_SO_LINGER
+        bool "Enable SO_LINGER processing"
+        default n
+        help
+            Enabling this option allows SO_LINGER processing.
+            When close socket, the TCP connection will be immediately disconnected.
+            The unsent data in the send buffer will be discarded and an RST message
+            will be sent to the other party. It is worth noting that because of this way,
+            the abnormal handshake in 4 ends the TCP connection, the TCP connection will
+            not enter the 'TIME_WAIT' state.
+
     config LWIP_SO_REUSE
         bool "Enable SO_REUSEADDR option"
         default y
diff --git a/components/lwip/port/esp32/include/lwipopts.h b/components/lwip/port/esp32/include/lwipopts.h
index 3e10020e0e..30f19ad679 100644
--- a/components/lwip/port/esp32/include/lwipopts.h
+++ b/components/lwip/port/esp32/include/lwipopts.h
@@ -538,6 +538,11 @@
  */
 #define LWIP_TCP_KEEPALIVE              1
 
+/**
+ * LWIP_SO_LINGER==1: Enable SO_LINGER processing.
+ */
+#define LWIP_SO_LINGER                  CONFIG_LWIP_SO_LINGER
+
 /**
  * LWIP_SO_RCVBUF==1: Enable SO_RCVBUF processing.
  */

From 15916dfbec8b1342157de41f59c810c2da63c9f3 Mon Sep 17 00:00:00 2001
From: xueyunfei <xueyunfei@espressif.com>
Date: Thu, 14 May 2020 15:18:39 +0800
Subject: [PATCH 2/2] add LINGER to menuconfig

---
 components/lwip/Kconfig | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/components/lwip/Kconfig b/components/lwip/Kconfig
index d6f2aa13fe..b78790a1d8 100644
--- a/components/lwip/Kconfig
+++ b/components/lwip/Kconfig
@@ -68,11 +68,14 @@ menu "LWIP"
         default n
         help
             Enabling this option allows SO_LINGER processing.
-            When close socket, the TCP connection will be immediately disconnected.
-            The unsent data in the send buffer will be discarded and an RST message
-            will be sent to the other party. It is worth noting that because of this way,
-            the abnormal handshake in 4 ends the TCP connection, the TCP connection will
-            not enter the 'TIME_WAIT' state.
+            l_onoff = 1,l_linger can set the timeout.
+
+            If l_linger=0, When a connection is closed, TCP will terminate the connection.
+            This means that TCP will discard any data packets stored in the socket send buffer
+            and send an RST to the peer.
+
+            If l_linger!=0,Then closesocket() calls to block the process until
+            the remaining data packets has been sent or timed out.
 
     config LWIP_SO_REUSE
         bool "Enable SO_REUSEADDR option"