From 4deb4936d52da88752da93f9cdc49541c10ef413 Mon Sep 17 00:00:00 2001
From: Paul Sokolovsky <pfalcon@users.sourceforge.net>
Date: Sat, 31 Oct 2015 19:48:54 +0300
Subject: [PATCH] extmod/modlwip: socket->incoming changed by async callbacks,
 must be volatile.

Otherwise for code like:

while (socket->incoming == NULL) {
    LWIP_DELAY(100);
}

a compiler may cache it in a register and it will be an infinite loop.
---
 extmod/modlwip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/extmod/modlwip.c b/extmod/modlwip.c
index ced9c06a1b..0f3ab7c155 100644
--- a/extmod/modlwip.c
+++ b/extmod/modlwip.c
@@ -184,7 +184,7 @@ typedef struct _lwip_socket_obj_t {
     mp_obj_base_t base;
 
     void *pcb;
-    void *incoming;
+    void *volatile incoming;
     byte peer[4];
     mp_uint_t peer_port;
     mp_uint_t timeout;