3334. [bug] Hold a zone table reference while performing a

                        asyncronous load of a zone. [RT #28326]

diff --git a/CHANGES b/CHANGES
index f0469c6d8382e0ab75c34537e2e42cb6aa8e52a9..c1b50975fd0c8d487f3c3cb68a0887c861c63e6c 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+3334.  [bug]           Hold a zone table reference while performing a
+                       asyncronous load of a zone. [RT #28326]
+
 3333.  [bug]           Setting resolver-query-timeout too low can cause
                        named to not recover if it looses connectivity.
                        [RT #29623]

diff --git a/lib/dns/zt.c b/lib/dns/zt.c
index 5bb4cb8b5beadc94a5afdea730f590da516b900f..eb1e42472475fc3105b263283f2f67435c3ef855 100644 (file)
--- a/lib/dns/zt.c
+++ b/lib/dns/zt.c
@@ -46,6 +46,7 @@ struct dns_zt {
        dns_zt_allloaded_t      loaddone;
        void *                  loaddone_arg;
        /* Locked by lock. */
+       isc_boolean_t           flush;
        isc_uint32_t            references;
        unsigned int            loads_pending;
        dns_rbt_t               *table;
@@ -93,8 +94,10 @@ dns_zt_create(isc_mem_t *mctx, dns_rdataclass_t rdclass, dns_zt_t **ztp)
        if (result != ISC_R_SUCCESS)
                goto cleanup_rbt;
 
-       zt->mctx = mctx;
+       zt->mctx = NULL;
+       isc_mem_attach(mctx, &zt->mctx);
        zt->references = 1;
+       zt->flush = ISC_FALSE;
        zt->rdclass = rdclass;
        zt->magic = ZTMAGIC;
        zt->loaddone = NULL;
@@ -200,6 +203,16 @@ flush(dns_zone_t *zone, void *uap) {
        return (dns_zone_flush(zone));
 }
 
+static void
+zt_destroy(dns_zt_t *zt) {
+       if (zt->flush)
+               (void)dns_zt_apply(zt, ISC_FALSE, flush, NULL);
+       dns_rbt_destroy(&zt->table);
+       isc_rwlock_destroy(&zt->rwlock);
+       zt->magic = 0;
+       isc_mem_putanddetach(&zt->mctx, zt, sizeof(*zt));
+}
+
 static void
 zt_flushanddetach(dns_zt_t **ztp, isc_boolean_t need_flush) {
        isc_boolean_t destroy = ISC_FALSE;
@@ -215,17 +228,13 @@ zt_flushanddetach(dns_zt_t **ztp, isc_boolean_t need_flush) {
        zt->references--;
        if (zt->references == 0)
                destroy = ISC_TRUE;
+       if (need_flush)
+               zt->flush = ISC_TRUE;
 
        RWUNLOCK(&zt->rwlock, isc_rwlocktype_write);
 
-       if (destroy) {
-               if (need_flush)
-                       (void)dns_zt_apply(zt, ISC_FALSE, flush, NULL);
-               dns_rbt_destroy(&zt->table);
-               isc_rwlock_destroy(&zt->rwlock);
-               zt->magic = 0;
-               isc_mem_put(zt->mctx, zt, sizeof(*zt));
-       }
+       if (destroy)
+               zt_destroy(zt);
 
        *ztp = NULL;
 }
@@ -272,10 +281,9 @@ dns_zt_asyncload(dns_zt_t *zt, dns_zt_allloaded_t alldone, void *arg) {
 
        REQUIRE(VALID_ZT(zt));
 
-       RWLOCK(&zt->rwlock, isc_rwlocktype_read);
+       RWLOCK(&zt->rwlock, isc_rwlocktype_write);
 
        INSIST(zt->loads_pending == 0);
-
        result = dns_zt_apply2(zt, ISC_FALSE, NULL, asyncload, &dl);
 
        pending = zt->loads_pending;
@@ -284,7 +292,7 @@ dns_zt_asyncload(dns_zt_t *zt, dns_zt_allloaded_t alldone, void *arg) {
                zt->loaddone_arg = arg;
        }
 
-       RWUNLOCK(&zt->rwlock, isc_rwlocktype_read);
+       RWUNLOCK(&zt->rwlock, isc_rwlocktype_write);
 
        if (pending == 0)
                alldone(arg);
@@ -305,10 +313,15 @@ asyncload(dns_zone_t *zone, void *callback) {
 
        REQUIRE(zone != NULL);
        zt = dns_zone_getview(zone)->zonetable;
+       INSIST(VALID_ZT(zt));
 
        result = dns_zone_asyncload(zone, *loaded, zt);
-       if (result == ISC_R_SUCCESS)
+       if (result == ISC_R_SUCCESS) {
+               INSIST(zt->references > 0);
+               zt->references++;
+               INSIST(zt->references != 0);
                zt->loads_pending++;
+       }
        return (ISC_R_SUCCESS);
 }
 
@@ -479,6 +492,7 @@ dns_zt_apply2(dns_zt_t *zt, isc_boolean_t stop, isc_result_t *sub,
  */
 static isc_result_t
 doneloading(dns_zt_t *zt, dns_zone_t *zone, isc_task_t *task) {
+       isc_boolean_t destroy = ISC_FALSE;
        dns_zt_allloaded_t alldone = NULL;
        void *arg = NULL;
 
@@ -489,6 +503,10 @@ doneloading(dns_zt_t *zt, dns_zone_t *zone, isc_task_t *task) {
 
        RWLOCK(&zt->rwlock, isc_rwlocktype_write);
        INSIST(zt->loads_pending != 0);
+       INSIST(zt->references != 0);
+       zt->references--;
+       if (zt->references == 0)
+               destroy = ISC_TRUE;
        zt->loads_pending--;
        if (zt->loads_pending == 0) {
                alldone = zt->loaddone;
@@ -501,6 +519,9 @@ doneloading(dns_zt_t *zt, dns_zone_t *zone, isc_task_t *task) {
        if (alldone != NULL)
                alldone(arg);
 
+       if (destroy)
+               zt_destroy(zt);
+
        return (ISC_R_SUCCESS);
 }