extmod/modlwip: socket->incoming changed by async callbacks, must be volatile.

Paul Sokolovsky · Paul Sokolovsky · commit 4deb4936d52d · 2015-10-31T19:51:23.000+03:00
Otherwise for code like:

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

a compiler may cache it in a register and it will be an infinite loop.
diff --git 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;
