Fix deadlock handling subscribe req during res_parking reload

Split destroy_hint method to separate hint removal and extension hint
state changed callback, the latter now called via stasis.
This avoids deadlock between res_parking reload that is removing the
parking lot and the related hint and subscribe requests coming for the
same parking lot.

ASTERISK-28173

Change-Id: I5b03c3455b3b12b6f83cea4cc34f4b4b20444f7e

diff --git a/main/pbx.c b/main/pbx.c
index 9e19f353c0a0edccfbc60344e00ef3f08c5440ae..ee5ed7ea9fce24bc0093ad033a45a508e654a6ac 100644 (file)
--- a/main/pbx.c
+++ b/main/pbx.c
@@ -346,6 +346,7 @@ struct ast_hint {
 };
 
 STASIS_MESSAGE_TYPE_DEFN_LOCAL(hint_change_message_type);
+STASIS_MESSAGE_TYPE_DEFN_LOCAL(hint_remove_message_type);
 
 #define HINTDEVICE_DATA_LENGTH 16
 AST_THREADSTORAGE(hintdevice_data);
@@ -3570,6 +3571,30 @@ static void device_state_cb(void *unused, struct stasis_subscription *sub, struc
                return;
        }
 
+       if (hint_remove_message_type() == stasis_message_type(msg)) {
+               /* The extension has already been destroyed */
+               struct ast_state_cb *state_cb;
+               struct ao2_iterator cb_iter;
+               struct ast_hint *hint = stasis_message_data(msg);
+
+               ao2_lock(hint);
+               hint->laststate = AST_EXTENSION_DEACTIVATED;
+               ao2_unlock(hint);
+
+               cb_iter = ao2_iterator_init(hint->callbacks, 0);
+               for (; (state_cb = ao2_iterator_next(&cb_iter)); ao2_ref(state_cb, -1)) {
+                       execute_state_callback(state_cb->change_cb,
+                               hint->context_name,
+                               hint->exten_name,
+                               state_cb->data,
+                               AST_HINT_UPDATE_DEVICE,
+                               hint,
+                               NULL);
+               }
+               ao2_iterator_destroy(&cb_iter);
+               return;
+       }
+
        if (ast_device_state_message_type() != stasis_message_type(msg)) {
                return;
        }
@@ -3855,34 +3880,7 @@ static void destroy_hint(void *obj)
        struct ast_hint *hint = obj;
        int i;
 
-       if (hint->callbacks) {
-               struct ast_state_cb *state_cb;
-               const char *context_name;
-               const char *exten_name;
-
-               if (hint->exten) {
-                       context_name = ast_get_context_name(ast_get_extension_context(hint->exten));
-                       exten_name = ast_get_extension_name(hint->exten);
-                       hint->exten = NULL;
-               } else {
-                       /* The extension has already been destroyed */
-                       context_name = hint->context_name;
-                       exten_name = hint->exten_name;
-               }
-               hint->laststate = AST_EXTENSION_DEACTIVATED;
-               while ((state_cb = ao2_callback(hint->callbacks, OBJ_UNLINK, NULL, NULL))) {
-                       /* Notify with -1 and remove all callbacks */
-                       execute_state_callback(state_cb->change_cb,
-                               context_name,
-                               exten_name,
-                               state_cb->data,
-                               AST_HINT_UPDATE_DEVICE,
-                               hint,
-                               NULL);
-                       ao2_ref(state_cb, -1);
-               }
-               ao2_ref(hint->callbacks, -1);
-       }
+       ao2_cleanup(hint->callbacks);
 
        for (i = 0; i < AST_VECTOR_SIZE(&hint->devices); i++) {
                char *device = AST_VECTOR_GET(&hint->devices, i);
@@ -3893,6 +3891,27 @@ static void destroy_hint(void *obj)
        ast_free(hint->last_presence_message);
 }
 
+/*! \brief Publish a hint removed event  */
+static int publish_hint_remove(struct ast_hint *hint)
+{
+       struct stasis_message *message;
+
+       if (!hint_remove_message_type()) {
+               return -1;
+       }
+
+       if (!(message = stasis_message_create(hint_remove_message_type(), hint))) {
+               ao2_ref(hint, -1);
+               return -1;
+       }
+
+       stasis_publish(ast_device_state_topic_all(), message);
+
+       ao2_ref(message, -1);
+
+       return 0;
+}
+
 /*! \brief Remove hint from extension */
 static int ast_remove_hint(struct ast_exten *e)
 {
@@ -3923,6 +3942,8 @@ static int ast_remove_hint(struct ast_exten *e)
        hint->exten = NULL;
        ao2_unlock(hint);
 
+       publish_hint_remove(hint);
+
        ao2_ref(hint, -1);
 
        return 0;
@@ -4029,8 +4050,7 @@ static int publish_hint_change(struct ast_hint *hint, struct ast_exten *ne)
                return -1;
        }
 
-       /* The message is going to be published to two topics so the hint needs two refs */
-       if (!(message = stasis_message_create(hint_change_message_type(), ao2_bump(hint)))) {
+       if (!(message = stasis_message_create(hint_change_message_type(), hint))) {
                ao2_ref(hint, -1);
                return -1;
        }
@@ -8418,6 +8438,7 @@ int load_pbx(void)
        }
        stasis_subscription_accept_message_type(device_state_sub, ast_device_state_message_type());
        stasis_subscription_accept_message_type(device_state_sub, hint_change_message_type());
+       stasis_subscription_accept_message_type(device_state_sub, hint_remove_message_type());
        stasis_subscription_set_filter(device_state_sub, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);
 
        if (!(presence_state_sub = stasis_subscribe(ast_presence_state_topic_all(), presence_state_cb, NULL))) {
@@ -8841,6 +8862,7 @@ static int statecbs_cmp(void *obj, void *arg, int flags)
 static void pbx_shutdown(void)
 {
        STASIS_MESSAGE_TYPE_CLEANUP(hint_change_message_type);
+       STASIS_MESSAGE_TYPE_CLEANUP(hint_remove_message_type);
 
        if (hints) {
                ao2_container_unregister("hints");
@@ -8938,6 +8960,9 @@ int ast_pbx_init(void)
        if (STASIS_MESSAGE_TYPE_INIT(hint_change_message_type) != 0) {
                return -1;
        }
+       if (STASIS_MESSAGE_TYPE_INIT(hint_remove_message_type) != 0) {
+               return -1;
+       }
 
        return (hints && hintdevices && autohints && statecbs) ? 0 : -1;
 }