extmod/modlwip: Don't require a port to define concurrency macros.
#define ip_reset_option(pcb, opt) ((pcb)->so_options &= ~(opt))
#endif
+// A port can define these hooks to provide concurrency protection
+#ifndef MICROPY_PY_LWIP_ENTER
+#define MICROPY_PY_LWIP_ENTER
+#define MICROPY_PY_LWIP_REENTER
+#define MICROPY_PY_LWIP_EXIT
+#endif
+
#ifdef MICROPY_PY_LWIP_SLIP
#include "netif/slipif.h"
#include "lwip/sio.h"
