res_pjsip_outbound_registration: Fix reload race condition.

Performing a CLI "module reload" command when there are new pjsip.conf
registration objects defined frequently failed to load them correctly.

What happens is a race condition between res_pjsip pushing its reload into
an asynchronous task processor task and the thread that does the rest of
the reloads when it gets to reloading the res_pjsip_outbound_registration
module.  A similar race condition happens between a reload and the CLI/AMI
show registrations commands.  The reload updates the current_states
container and the CLI/AMI commands call get_registrations() which builds a
new current_states container.

* Made res_pjsip.c reload_module() use ast_sip_push_task_synchronous()
instead of ast_sip_push_task() to eliminate two threads processing config
reloads at the same time.

* Made get_registrations() not replace the global current_states container
so the CLI/AMI show registrations command cannot interfere with reloading.
You could never add/remove objects in the container without the
possibility of the container being replaced out from under you by
get_registrations().

* Added a registration loaded sorcery instance observer to purge any dead
registration objects since get_registrations() cannot do this job anymore.
The struct ast_sorcery_instance_observer callbacks must be used because
the callback happens inline with the load process.  The struct
ast_sorcery_observer callbacks are pushed to a different thread.

* Added some global current_states NULL pointer checks in case the
container disappears because of unload_module().

* Made sorcery's struct ast_sorcery_instance_observer.object_type_loaded
callbacks guaranteed to be called before any struct
ast_sorcery_observer.loaded callbacks will be called.

* Moved the check for non-reloadable objects to before the sorcery
instance loading callbacks happen to short circuit unnecessary work.
Previously with non-reloadable objects, the sorcery instance
loading/loaded callbacks would always happen, the individual wizard
loading/loaded would be prevented, and the non-reloadable type logging
message would be logged for each associated wizard.

ASTERISK-24729 #close
Review: https://reviewboard.asterisk.org/r/4381/
........

Merged revisions 431243 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@431251 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 14 insertions, 11 deletions

diff --git a/main/sorcery.c b/main/sorcery.c
index bd919a40b..50e5e4756 100644
--- a/main/sorcery.c
+++ b/main/sorcery.c
@@ -1176,12 +1176,6 @@ static int sorcery_wizard_load(void *obj, void *arg, int flags)
 	struct sorcery_load_details *details = arg;
 	void (*load)(void *data, const struct ast_sorcery *sorcery, const char *type);
 
-	if (details->reload && !sorcery_reloadable(details->sorcery, details->type)) {
-		ast_log(LOG_NOTICE, "Type '%s' is not reloadable, "
-			"maintaining previous values\n", details->type);
-		return 0;
-	}
-
 	load = !details->reload ? wizard->wizard->callbacks.load : wizard->wizard->callbacks.reload;
 
 	if (load) {
@@ -1256,22 +1250,31 @@ static int sorcery_object_load(void *obj, void *arg, int flags)
 
 	details->type = type->name;
 
+	if (details->reload && !sorcery_reloadable(details->sorcery, details->type)) {
+		ast_log(LOG_NOTICE, "Type '%s' is not reloadable, maintaining previous values\n",
+			details->type);
+		return 0;
+	}
+
 	NOTIFY_INSTANCE_OBSERVERS(details->sorcery->observers, object_type_loading,
 		details->sorcery->module_name, details->sorcery, type->name, details->reload);
 
 	ao2_callback(type->wizards, OBJ_NODATA, sorcery_wizard_load, details);
 
+	NOTIFY_INSTANCE_OBSERVERS(details->sorcery->observers, object_type_loaded,
+		details->sorcery->module_name, details->sorcery, type->name, details->reload);
+
 	if (ao2_container_count(type->observers)) {
-		struct sorcery_observer_invocation *invocation = sorcery_observer_invocation_alloc(type, NULL);
+		struct sorcery_observer_invocation *invocation;
 
-		if (invocation && ast_taskprocessor_push(type->serializer, sorcery_observers_notify_loaded, invocation)) {
+		invocation = sorcery_observer_invocation_alloc(type, NULL);
+		if (invocation
+			&& ast_taskprocessor_push(type->serializer, sorcery_observers_notify_loaded,
+				invocation)) {
 			ao2_cleanup(invocation);
 		}
 	}
 
-	NOTIFY_INSTANCE_OBSERVERS(details->sorcery->observers, object_type_loaded,
-		details->sorcery->module_name, details->sorcery, type->name, details->reload);
-
 	return 0;
 }