From 98d50159165194bf3ee374aa681c5957c86e2f97 Mon Sep 17 00:00:00 2001
From: Marcel Holtmann <marcel@holtmann.org>
Date: Tue, 10 Feb 2026 16:53:59 +0100
Subject: [PATCH] tools: Fix build issue with missing _GNU_SOURCE
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  CC       tools/probe-req.o
tools/probe-req.c: In function ‘get_interface_callback’:
tools/probe-req.c:122:22: error: storage size of ‘ifr’ isn’t known
  122 |         struct ifreq ifr;
      |                      ^~~
tools/probe-req.c:155:42: error: ‘IFF_UP’ undeclared (first use in this function)
  155 |         if (r == -1 || !(ifr.ifr_flags & IFF_UP))
      |                                          ^~~~~~
tools/probe-req.c:155:42: note: each undeclared identifier is reported only once for each function it appears in
tools/probe-req.c:122:22: error: unused variable ‘ifr’ [-Werror=unused-variable]
  122 |         struct ifreq ifr;
      |                      ^~~
---
 tools/probe-req.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/probe-req.c b/tools/probe-req.c
index 7ec8e3af..86fe48ee 100644
--- a/tools/probe-req.c
+++ b/tools/probe-req.c
@@ -24,6 +24,7 @@
 #include <config.h>
 #endif
 
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>