Merge branch 'feature/config_to_disable_solink_at_socket_mt' into 'master'

Add configuration to enable/disable setting SO_LINGER default

See merge request sdk/ESP8266_RTOS_SDK!693

Author: donghengqaz

components/lwip/Kconfig

@@ -63,6 +63,17 @@ config LWIP_SOCKET_MULTITHREAD
         Enable the option can enable LWIP socket multithread and all
         function will be thread safe.
 
+config SET_SOLINGER_DEFAULT
+    bool "set socket SO_LINGER default"
+    default y
+    depends on LWIP_SOCKET_MULTITHREAD
+    help
+        The function is only used by socket multi-thread.
+
+        Enable this option can set the target socket to enable the "SO_LINGER" and config timeout to be "0" when it is created.
+        It means that if close the socket, all send queue will be dropped, so heap memory can be collected immediately,
+        but some packets which are waiting to be sent will lost.
+
 config ESP_UDP_SYNC_SEND
     bool "LWIP socket UDP sync send"
     default y

components/lwip/apps/multi-threads/sockets_mt.c

@@ -522,6 +522,7 @@ static void lwip_sync_mt(int s, int how)
     }  while (lock < SOCK_MT_LOCK_MAX);
 }
 
+#if SET_SOLINGER_DEFAULT
 #if LWIP_SO_LINGER
 static void lwip_socket_set_so_link(int s, int linger)
 {
@@ -538,8 +539,8 @@ static void lwip_socket_set_so_link(int s, int linger)
 }
 #else
 #error "LWIP_SO_LINGER must be enable"
-#endif
-
+#endif /* LWIP_SO_LINGER */
+#endif /* SET_SOLINGER_DEFAULT */
 
 int lwip_socket(int domain, int type, int protocol)
 {

components/lwip/port/esp8266/include/lwipopts.h

@@ -1452,6 +1452,8 @@ size_t memp_malloc_get_size(size_t type);
  */
 #define LWIP_SO_LINGER                  1
 
+#define SET_SOLINGER_DEFAULT            CONFIG_SET_SOLINGER_DEFAULT
+
 /**
  * If LWIP_SO_RCVBUF is used, this is the default value for recv_bufsize.
  */