res_pjsip: make it unloadable (take 2)

Due to the original patch causing memory corruptions it was removed until the
problem could be resolved. This patch is the original patch plus some added
locking around stasis router subcription that was needed to avoid the memory
corruption.

Description of the original problem and patch (still applicable):

The res_pjsip module was previously unloadable. With this patch it can now
be unloaded.

This patch is based off the original patch on the issue (listed below) by Corey
Farrell with a few modifications. Namely, removed a few changes not required to
make the module unloadable and also fixed a bug that would cause asterisk to
crash on unloading.

This patch is the first step (should hopefully be followed by another/others at
some point) in allowing res_pjsip and the modules that depend on it to be
unloadable. At this time, res_pjsip and some of the modules that depend on
res_pjsip cannot be unloaded without causing problems of some sort.

The goal of this patch is to get res_pjsip and only res_pjsip to be able to
unload successfully and/or shutdown without incident (crashes, leaks, etc...).
Other dependent modules may still cause problems on unload.

Basically made sure, with the patch applied, that res_pjsip (with no other
dependent modules loaded) could be succesfully unloaded and Asterisk could
shutdown without any leaks or crashes that pertained directly to res_pjsip.

ASTERISK-24485 #close
Reported by: Corey Farrell
Review: https://reviewboard.asterisk.org/r/4363/
patches:
  pjsip_unload-broken-r1.patch submitted by Corey Farrell (license 5909)
........

Merged revisions 431179 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@431180 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 87 insertions, 13 deletions

diff --git a/res/res_pjsip.c b/res/res_pjsip.c
index 5a809097e..b2b7d6358 100644
--- a/res/res_pjsip.c
+++ b/res/res_pjsip.c
@@ -40,6 +40,8 @@
 /*** MODULEINFO
 	<depend>pjproject</depend>
 	<depend>res_sorcery_config</depend>
+	<depend>res_sorcery_memory</depend>
+	<depend>res_sorcery_astdb</depend>
 	<support_level>core</support_level>
  ***/
 
@@ -1811,7 +1813,7 @@ static pjsip_endpoint *ast_pjsip_endpoint;
 
 static struct ast_threadpool *sip_threadpool;
 
-static int register_service(void *data)
+static int register_service_noref(void *data)
 {
 	pjsip_module **module = data;
 	if (!ast_pjsip_endpoint) {
@@ -1823,19 +1825,33 @@ static int register_service(void *data)
 		return -1;
 	}
 	ast_debug(1, "Registered SIP service %.*s (%p)\n", (int) pj_strlen(&(*module)->name), pj_strbuf(&(*module)->name), *module);
-	ast_module_ref(ast_module_info->self);
 	return 0;
 }
 
+static int register_service(void *data)
+{
+	int res;
+
+	if (!(res = register_service_noref(data))) {
+		ast_module_ref(ast_module_info->self);
+	}
+
+	return res;
+}
+
+int internal_sip_register_service(pjsip_module *module)
+{
+	return ast_sip_push_task_synchronous(NULL, register_service_noref, &module);
+}
+
 int ast_sip_register_service(pjsip_module *module)
 {
 	return ast_sip_push_task_synchronous(NULL, register_service, &module);
 }
 
-static int unregister_service(void *data)
+static int unregister_service_noref(void *data)
 {
 	pjsip_module **module = data;
-	ast_module_unref(ast_module_info->self);
 	if (!ast_pjsip_endpoint) {
 		return -1;
 	}
@@ -1844,6 +1860,22 @@ static int unregister_service(void *data)
 	return 0;
 }
 
+static int unregister_service(void *data)
+{
+	int res;
+
+	if (!(res = unregister_service_noref(data))) {
+		ast_module_unref(ast_module_info->self);
+	}
+
+	return res;
+}
+
+int internal_sip_unregister_service(pjsip_module *module)
+{
+	return ast_sip_push_task_synchronous(NULL, unregister_service_noref, &module);
+}
+
 void ast_sip_unregister_service(pjsip_module *module)
 {
 	ast_sip_push_task_synchronous(NULL, unregister_service, &module);
@@ -1990,26 +2022,38 @@ struct ast_sip_endpoint *ast_sip_identify_endpoint(pjsip_rx_data *rdata)
 
 AST_RWLIST_HEAD_STATIC(endpoint_formatters, ast_sip_endpoint_formatter);
 
-int ast_sip_register_endpoint_formatter(struct ast_sip_endpoint_formatter *obj)
+void internal_sip_register_endpoint_formatter(struct ast_sip_endpoint_formatter *obj)
 {
 	SCOPED_LOCK(lock, &endpoint_formatters, AST_RWLIST_WRLOCK, AST_RWLIST_UNLOCK);
 	AST_RWLIST_INSERT_TAIL(&endpoint_formatters, obj, next);
+}
+
+int ast_sip_register_endpoint_formatter(struct ast_sip_endpoint_formatter *obj)
+{
+	internal_sip_register_endpoint_formatter(obj);
 	ast_module_ref(ast_module_info->self);
 	return 0;
 }
 
-void ast_sip_unregister_endpoint_formatter(struct ast_sip_endpoint_formatter *obj)
+int internal_sip_unregister_endpoint_formatter(struct ast_sip_endpoint_formatter *obj)
 {
 	struct ast_sip_endpoint_formatter *i;
 	SCOPED_LOCK(lock, &endpoint_formatters, AST_RWLIST_WRLOCK, AST_RWLIST_UNLOCK);
 	AST_RWLIST_TRAVERSE_SAFE_BEGIN(&endpoint_formatters, i, next) {
 		if (i == obj) {
 			AST_RWLIST_REMOVE_CURRENT(next);
-			ast_module_unref(ast_module_info->self);
 			break;
 		}
 	}
 	AST_RWLIST_TRAVERSE_SAFE_END;
+	return i == obj ? 0 : -1;
+}
+
+void ast_sip_unregister_endpoint_formatter(struct ast_sip_endpoint_formatter *obj)
+{
+	if (!internal_sip_unregister_endpoint_formatter(obj)) {
+		ast_module_unref(ast_module_info->self);
+	}
 }
 
 int ast_sip_format_endpoint_ami(struct ast_sip_endpoint *endpoint,
@@ -3234,7 +3278,7 @@ static int load_module(void)
 		return AST_MODULE_LOAD_DECLINE;
 	}
 
-	if (ast_sip_register_service(&supplement_module)) {
+	if (internal_sip_register_service(&supplement_module)) {
 		ast_log(LOG_ERROR, "Failed to initialize supplement hooks. Aborting load\n");
 		ast_sip_destroy_distributor();
 		ast_res_pjsip_destroy_configuration();
@@ -3249,9 +3293,9 @@ static int load_module(void)
 		return AST_MODULE_LOAD_DECLINE;
 	}
 
-	if (ast_sip_initialize_outbound_authentication()) {
+	if (internal_sip_initialize_outbound_authentication()) {
 		ast_log(LOG_ERROR, "Failed to initialize outbound authentication. Aborting load\n");
-		ast_sip_unregister_service(&supplement_module);
+		internal_sip_unregister_service(&supplement_module);
 		ast_sip_destroy_distributor();
 		ast_res_pjsip_destroy_configuration();
 		ast_sip_destroy_global_headers();
@@ -3267,8 +3311,6 @@ static int load_module(void)
 
 	ast_res_pjsip_init_options_handling(0);
 
-	ast_module_ref(ast_module_info->self);
-
 	return AST_MODULE_LOAD_SUCCESS;
 }
 
@@ -3282,9 +3324,41 @@ static int reload_module(void)
 	return 0;
 }
 
+static int unload_pjsip(void *data)
+{
+	if (memory_pool) {
+		pj_pool_release(memory_pool);
+		memory_pool = NULL;
+	}
+	if (ast_pjsip_endpoint) {
+		pjsip_endpt_destroy(ast_pjsip_endpoint);
+		ast_pjsip_endpoint = NULL;
+	}
+	pj_caching_pool_destroy(&caching_pool);
+	pj_shutdown();
+	return 0;
+}
+
 static int unload_module(void)
 {
-	/* This will never get called as this module can't be unloaded */
+	ast_res_pjsip_cleanup_options_handling();
+	internal_sip_destroy_outbound_authentication();
+	ast_sip_destroy_distributor();
+	ast_res_pjsip_destroy_configuration();
+	ast_sip_destroy_system();
+	ast_sip_destroy_global_headers();
+	internal_sip_unregister_service(&supplement_module);
+	if (monitor_thread) {
+		stop_monitor_thread();
+	}
+	/* The thread this is called from cannot call PJSIP/PJLIB functions,
+	 * so we have to push the work to the threadpool to handle
+	 */
+	ast_sip_push_task_synchronous(NULL, unload_pjsip, NULL);
+
+	ast_threadpool_shutdown(sip_threadpool);
+
+	ast_sip_destroy_cli();
 	return 0;
 }