1 files changed, 13 insertions, 2 deletions
diff --git a/src/xt.c b/src/xt.c
index d774e073..bb87e86e 100644
--- a/src/xt.c
+++ b/src/xt.c
@@ -361,7 +361,18 @@ static struct xtables_globals xt_nft_globals = {
 
 void xt_init(void)
 {
-	/* Default to IPv4, but this changes in runtime */
-	xtables_init_all(&xt_nft_globals, NFPROTO_IPV4);
+	static bool init_once;
+
+	if (!init_once) {
+		/* libxtables is full of global variables and cannot be used
+		 * concurrently by multiple threads. Hence, it's fine that the
+		 * "init_once" guard is not thread-safe either.
+		 * Don't link against xtables if you want thread safety.
+		 */
+		init_once = true;
+
+		/* Default to IPv4, but this changes in runtime */
+		xtables_init_all(&xt_nft_globals, NFPROTO_IPV4);
+	}
 }
 #endif