From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Thu, 6 Dec 2018 16:09:32 +0000 (-0500)
Subject: Stop the application registration thread before orphaned threads
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=bd9addf713e7dc8fc47499f62312966a3a5f4d46

Stop the application registration thread before orphaned threads

The application registration thread receives new connections from
applications, provides them to the dispatch thread. The dispatch
thread, in turn, forwards the command and notification sockets of
applications (liblttng-ust) to the application management and
application notification threads.

Not shutting down the application registration thread is problematic
since application connections will be accepted but not associated
to an "ust_app" structure as the following threads are no longer
present.

The remaining threads can then be safely torn down as part of the
orphaned threads.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 5f7600c0c..a96dc5195 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -1354,6 +1354,7 @@ int main(int argc, char **argv)
 	struct rotation_thread_timer_queue *rotation_timer_queue = NULL;
 	struct lttng_thread *client_thread = NULL;
 	struct lttng_thread *notification_thread = NULL;
+	struct lttng_thread *register_apps_thread = NULL;
 
 	init_kernel_workarounds();
 
@@ -1747,7 +1748,9 @@ int main(int argc, char **argv)
 	}
 
 	/* Create thread to manage application registration. */
-	if (!launch_application_registration_thread(&ust_cmd_queue)) {
+	register_apps_thread = launch_application_registration_thread(
+			&ust_cmd_queue);
+	if (!register_apps_thread) {
 		retval = -1;
 		goto exit_reg_apps;
 	}
@@ -1815,6 +1818,10 @@ exit_kernel:
 exit_agent_reg:
 exit_apps_notify:
 exit_apps:
+	if (register_apps_thread) {
+		lttng_thread_shutdown(register_apps_thread);
+		lttng_thread_put(register_apps_thread);
+	}
 exit_reg_apps:
 exit_dispatch:
 exit_client:
diff --git a/src/bin/lttng-sessiond/register.c b/src/bin/lttng-sessiond/register.c
index b75db4ed9..6776019c6 100644
--- a/src/bin/lttng-sessiond/register.c
+++ b/src/bin/lttng-sessiond/register.c
@@ -361,7 +361,7 @@ static bool shutdown_application_registration_thread(void *data)
 	return notify_thread_pipe(write_fd) == 1;
 }
 
-bool launch_application_registration_thread(
+struct lttng_thread *launch_application_registration_thread(
 		struct ust_cmd_queue *cmd_queue)
 {
 	struct lttng_pipe *quit_pipe;
@@ -388,9 +388,8 @@ bool launch_application_registration_thread(
 	if (!thread) {
 		goto error;
 	}
-	lttng_thread_put(thread);
-	return true;
+	return thread;
 error:
 	cleanup_application_registration_thread(notifiers);
-	return false;
+	return NULL;
 }
diff --git a/src/bin/lttng-sessiond/register.h b/src/bin/lttng-sessiond/register.h
index 71bb4de1e..d9bd05155 100644
--- a/src/bin/lttng-sessiond/register.h
+++ b/src/bin/lttng-sessiond/register.h
@@ -23,6 +23,7 @@
 #include <stdbool.h>
 #include "lttng-sessiond.h"
 
-bool launch_application_registration_thread(struct ust_cmd_queue *cmd_queue);
+struct lttng_thread *launch_application_registration_thread(
+		struct ust_cmd_queue *cmd_queue);
 
 #endif /* SESSIOND_APPLICATION_REGISTRATION_THREAD_H */