[rt36341]

3905.   [bug]           Address deadlock between view.c and adb.c. [RT #36341]

diff --git a/CHANGES b/CHANGES
index 059f61e453e1696cceeb36dca7557ee2cab70321..c3ac17412b5f5a03583d3fb533554eb4bf1ab514 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+3905.  [bug]           Address deadlock between view.c and adb.c. [RT #36341]
+
 3904.  [func]          Add the RPZ SOA to the additional section. [RT36507]
 
 3903.  [bug]           Improve the accuracy of DiG's reported round trip

diff --git a/lib/dns/adb.c b/lib/dns/adb.c
index 2563d4a4757bc9c251f8bde5fc8f8c0e23cf260f..8dd7d222f4ce3ce4cedd0038e3af88ed291096a7 100644 (file)
--- a/lib/dns/adb.c
+++ b/lib/dns/adb.c
@@ -15,8 +15,6 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id$ */
-
 /*! \file
  *
  * \note
@@ -157,7 +155,7 @@ struct dns_adb {
        unsigned int                    *entry_refcnt;
 
        isc_event_t                     cevent;
-       isc_boolean_t                   cevent_sent;
+       isc_boolean_t                   cevent_out;
        isc_boolean_t                   shutting_down;
        isc_eventlist_t                 whenshutdown;
        isc_event_t                     growentries;
@@ -324,6 +322,7 @@ static void water(void *, int);
 static void dump_entry(FILE *, dns_adbentry_t *, isc_boolean_t, isc_stdtime_t);
 static void adjustsrtt(dns_adbaddrinfo_t *addr, unsigned int rtt,
                       unsigned int factor, isc_stdtime_t now);
+static void shutdown_task(isc_task_t *task, isc_event_t *ev);
 
 /*
  * MUST NOT overlap DNS_ADBFIND_* flags!
@@ -1501,10 +1500,13 @@ check_exit(dns_adb_t *adb) {
                 * If there aren't any external references either, we're
                 * done.  Send the control event to initiate shutdown.
                 */
-               INSIST(!adb->cevent_sent);      /* Sanity check. */
+               INSIST(!adb->cevent_out);      /* Sanity check. */
+               ISC_EVENT_INIT(&adb->cevent, sizeof(adb->cevent), 0, NULL,
+                              DNS_EVENT_ADBCONTROL, shutdown_task, adb,
+                              adb, NULL, NULL);
                event = &adb->cevent;
                isc_task_send(adb->task, &event);
-               adb->cevent_sent = ISC_TRUE;
+               adb->cevent_out = ISC_TRUE;
        }
 }
 
@@ -2434,10 +2436,9 @@ dns_adb_create(isc_mem_t *mem, dns_view_t *view, isc_timermgr_t *timermgr,
        adb->view = view;
        adb->taskmgr = taskmgr;
        adb->next_cleanbucket = 0;
-       ISC_EVENT_INIT(&adb->cevent, sizeof(adb->cevent), 0, NULL,
-                      DNS_EVENT_ADBCONTROL, shutdown_task, adb,
-                      adb, NULL, NULL);
-       adb->cevent_sent = ISC_FALSE;
+       ISC_EVENT_INIT(&adb->cevent, sizeof(adb->cevent),
+                      0, NULL, 0, NULL, NULL, NULL, NULL, NULL);
+       adb->cevent_out = ISC_FALSE;
        adb->shutting_down = ISC_FALSE;
        ISC_LIST_INIT(adb->whenshutdown);
 
@@ -2471,7 +2472,7 @@ dns_adb_create(isc_mem_t *mem, dns_view_t *view, isc_timermgr_t *timermgr,
                                 "intializing table sizes to %u\n",
                                 nbuckets[11]);
                adb->nentries = nbuckets[11];
-               adb->nnames= nbuckets[11];
+               adb->nnames = nbuckets[11];
 
        }
 
@@ -2744,9 +2745,28 @@ dns_adb_whenshutdown(dns_adb_t *adb, isc_task_t *task, isc_event_t **eventp) {
        UNLOCK(&adb->lock);
 }
 
+static void
+shutdown_stage2(isc_task_t *task, isc_event_t *event) {
+       dns_adb_t *adb;
+
+       UNUSED(task);
+
+       adb = event->ev_arg;
+       INSIST(DNS_ADB_VALID(adb));
+
+       LOCK(&adb->lock);
+       INSIST(adb->shutting_down);
+       adb->cevent_out = ISC_FALSE;
+       (void)shutdown_names(adb);
+       (void)shutdown_entries(adb);
+       if (dec_adb_irefcnt(adb))
+               check_exit(adb);
+       UNLOCK(&adb->lock);
+}
+
 void
 dns_adb_shutdown(dns_adb_t *adb) {
-       isc_boolean_t need_check_exit;
+       isc_event_t *event;
 
        /*
         * Shutdown 'adb'.
@@ -2757,11 +2777,16 @@ dns_adb_shutdown(dns_adb_t *adb) {
        if (!adb->shutting_down) {
                adb->shutting_down = ISC_TRUE;
                isc_mem_setwater(adb->mctx, water, adb, 0, 0);
-               need_check_exit = shutdown_names(adb);
-               if (!need_check_exit)
-                       need_check_exit = shutdown_entries(adb);
-               if (need_check_exit)
-                       check_exit(adb);
+               /*
+                * Isolate shutdown_names and shutdown_entries calls.
+                */
+               inc_adb_irefcnt(adb);
+               ISC_EVENT_INIT(&adb->cevent, sizeof(adb->cevent), 0, NULL,
+                              DNS_EVENT_ADBCONTROL, shutdown_stage2, adb,
+                              adb, NULL, NULL);
+               adb->cevent_out = ISC_TRUE;
+               event = &adb->cevent;
+               isc_task_send(adb->task, &event);
        }
 
        UNLOCK(&adb->lock);