Add shutdown signaling for catalog zones

This change should make sure that catalog zone update processing
doesn't happen when the catalog zone is being shut down. This
should help avoid races when offloading the catalog zone updates
in the follow-up commit.

lib/dns/catz.c

@@ -69,6 +69,7 @@ struct dns_catz_entry {
  */
 struct dns_catz_zone {
 	unsigned int magic;
+	isc_loop_t *loop;
 	dns_name_t name;
 	dns_catz_zones_t *catzs;
 	dns_rdata_t soa;
@@ -101,6 +102,8 @@ struct dns_catz_zone {
 
 static void
 dns__catz_timer_start(dns_catz_zone_t *catz);
+static void
+dns__catz_timer_stop(void *arg);
 
 static isc_result_t
 catz_process_zones_entry(dns_catz_zone_t *catz, dns_rdataset_t *value,
@@ -126,6 +129,7 @@ struct dns_catz_zones {
 	dns_catz_zonemodmethods_t *zmm;
 	isc_loopmgr_t *loopmgr;
 	dns_view_t *view;
+	atomic_bool shuttingdown;
 };
 
 void
@@ -820,11 +824,26 @@ dns__catz_timer_start(dns_catz_zone_t *catz) {
 		isc_interval_set(&interval, 0, 0);
 	}
 
-	isc_timer_create(isc_loop_current(catz->catzs->loopmgr),
-			 dns_catz_update_action, catz, &catz->updatetimer);
+	catz->loop = isc_loop_current(catz->catzs->loopmgr);
+
+	isc_timer_create(catz->loop, dns_catz_update_action, catz,
+			 &catz->updatetimer);
 	isc_timer_start(catz->updatetimer, isc_timertype_once, &interval);
 }
 
+static void
+dns__catz_timer_stop(void *arg) {
+	dns_catz_zone_t *catz = arg;
+	REQUIRE(DNS_CATZ_ZONE_VALID(catz));
+
+	isc_timer_stop(catz->updatetimer);
+	isc_timer_destroy(&catz->updatetimer);
+	catz->loop = NULL;
+
+	dns_catz_unref_catzs(catz->catzs);
+	dns_catz_detach_catz(&catz);
+}
+
 isc_result_t
 dns_catz_add_zone(dns_catz_zones_t *catzs, const dns_name_t *name,
 		  dns_catz_zone_t **catzp) {
@@ -888,6 +907,20 @@ dns_catz_get_zone(dns_catz_zones_t *catzs, const dns_name_t *name) {
 	return (found);
 }
 
+static void
+dns__catz_shutdown(dns_catz_zone_t *catz) {
+	/* lock must be locked */
+	if (catz->updatetimer != NULL) {
+		/* Don't wait for timer to trigger for shutdown */
+		INSIST(catz->loop != NULL);
+
+		dns_catz_ref_catzs(catz->catzs);
+		isc_async_run(catz->loop, dns__catz_timer_stop, catz);
+	} else {
+		dns_catz_detach_catz(&catz);
+	}
+}
+
 static void
 dns__catz_zone_destroy(dns_catz_zone_t *catz) {
 	isc_mem_t *mctx = catz->catzs->mctx;
@@ -959,27 +992,44 @@ dns__catz_zone_destroy(dns_catz_zone_t *catz) {
 
 static void
 dns__catz_zones_destroy(dns_catz_zones_t *catzs) {
+	REQUIRE(atomic_load(&catzs->shuttingdown));
+	REQUIRE(catzs->zones == NULL);
+
+	catzs->magic = 0;
+	isc_mutex_destroy(&catzs->lock);
+	isc_refcount_destroy(&catzs->references);
+
+	isc_mem_putanddetach(&catzs->mctx, catzs, sizeof(*catzs));
+}
+
+void
+dns_catz_shutdown_catzs(dns_catz_zones_t *catzs) {
+	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
+
+	if (!atomic_compare_exchange_strong(&catzs->shuttingdown,
+					    &(bool){ false }, true))
+	{
+		return;
+	}
+
+	LOCK(&catzs->lock);
 	if (catzs->zones != NULL) {
 		isc_ht_iter_t *iter = NULL;
 		isc_result_t result;
 		isc_ht_iter_create(catzs->zones, &iter);
 		for (result = isc_ht_iter_first(iter); result == ISC_R_SUCCESS;)
 		{
-			dns_catz_zone_t *zone = NULL;
-			isc_ht_iter_current(iter, (void **)&zone);
+			dns_catz_zone_t *catz = NULL;
+			isc_ht_iter_current(iter, (void **)&catz);
 			result = isc_ht_iter_delcurrent_next(iter);
-			dns_catz_detach_catz(&zone);
+			dns__catz_shutdown(catz);
 		}
 		INSIST(result == ISC_R_NOMORE);
 		isc_ht_iter_destroy(&iter);
 		INSIST(isc_ht_count(catzs->zones) == 0);
 		isc_ht_destroy(&catzs->zones);
 	}
-	catzs->magic = 0;
-	isc_mutex_destroy(&catzs->lock);
-	isc_refcount_destroy(&catzs->references);
-
-	isc_mem_putanddetach(&catzs->mctx, catzs, sizeof(*catzs));
+	UNLOCK(&catzs->lock);
 }
 
 #ifdef DNS_CATZ_TRACE
@@ -1991,6 +2041,7 @@ dns_catz_update_action(void *arg) {
 	dns_catz_update_from_db(catz->db, catz->catzs);
 	isc_timer_stop(catz->updatetimer);
 	isc_timer_destroy(&catz->updatetimer);
+	catz->loop = NULL;
 	result = isc_time_now(&catz->lastupdated);
 	RUNTIME_CHECK(result == ISC_R_SUCCESS);
 	UNLOCK(&catz->catzs->lock);
@@ -2083,6 +2134,10 @@ dns_catz_update_from_db(dns_db_t *db, dns_catz_zones_t *catzs) {
 	REQUIRE(DNS_DB_VALID(db));
 	REQUIRE(DNS_CATZ_ZONES_VALID(catzs));
 
+	if (atomic_load(&catzs->shuttingdown)) {
+		return;
+	}
+
 	dns_name_format(&db->origin, bname, DNS_NAME_FORMATSIZE);
 
 	/*

lib/dns/include/dns/catz.h

@@ -438,6 +438,16 @@ dns_catz_get_iterator(dns_catz_zone_t *catz, isc_ht_iter_t **itp);
  *
  */
 
+void
+dns_catz_shutdown_catzs(dns_catz_zones_t *catzs);
+/*%<
+ * Shut down the catalog zones.
+ *
+ * Requires:
+ * \li	'catzs' is a valid dns_catz_zones_t.
+ *
+ */
+
 #ifdef DNS_CATZ_TRACE
 /* Compatibility macros */
 #define dns_catz_attach_catz(catz, catzp) \

lib/dns/view.c

@@ -300,6 +300,7 @@ destroy(dns_view_t *view) {
 		dns_rpz_detach_rpzs(&view->rpzs);
 	}
 	if (view->catzs != NULL) {
+		dns_catz_shutdown_catzs(view->catzs);
 		dns_catz_detach_catzs(&view->catzs);
 	}
 	for (dlzdb = ISC_LIST_HEAD(view->dlz_searched); dlzdb != NULL;
@@ -548,6 +549,7 @@ dns_view_detach(dns_view_t **viewp) {
 			}
 		}
 		if (view->catzs != NULL) {
+			dns_catz_shutdown_catzs(view->catzs);
 			dns_catz_detach_catzs(&view->catzs);
 		}
 		if (view->ntatable_priv != NULL) {