From: Alessio Podda <alessio@isc.org>
Date: Mon, 13 Jul 2026 15:44:48 +0000 (+0200)
Subject: Atomic rpz shutdown
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c94e199f0440e7ad1e3a2e7c957a8e6fdd1d626d;p=thirdparty%2Fbind9.git

Atomic rpz shutdown

The shutdown flag is monotonic (it always starts false, eventually
becomes true and stays that way), so it does not need mutex protection.
---

diff --git a/lib/dns/rpz.c b/lib/dns/rpz.c
index 54c88de550d..3eaaddfaee0 100644
--- a/lib/dns/rpz.c
+++ b/lib/dns/rpz.c
@@ -2181,11 +2181,14 @@ dns_rpz_zones_shutdown(dns_rpz_zones_t *rpzs) {
 	REQUIRE(DNS_RPZ_ZONES_VALID(rpzs));
 	/*
 	 * Forget the last of the view's rpz machinery when shutting down.
+	 *
+	 * shuttingdown is monotonic: it changes from false to true and is never
+	 * cleared.  Publish it without taking update_lock or data_lock so
+	 * workers can observe shutdown immediately.  atomic_exchange() also
+	 * preserves idempotency: only the caller that changes the flag performs
+	 * the per-zone shutdown work.
 	 */
-
-	if (!atomic_compare_exchange_strong(&rpzs->shuttingdown,
-					    &(bool){ false }, true))
-	{
+	if (atomic_exchange(&rpzs->shuttingdown, true)) {
 		return;
 	}