[lttng-dev] [RFC PATCH v2 10/13] Teardown apps_notify_thread before thread_manage_apps
Jonathan Rajotte
jonathan.rajotte-julien at efficios.com
Mon Sep 18 22:52:03 UTC 2017
RFC:
This is necessary since we use the ust_app_ht_by_notify_sock to
perform the cleanup operation. Since both ust_app_unregister and
ust_app_ust_app_notify_unregister perform a remove of the app on the
ust_ust_app_by_notify_sock but only ust_app_notify_unregister actually
end up performing a close(call_rcu) on the socket.
Other way to do fix this problem?
Could we simply not remove it on a ust_app_unregister? And always defer
to the apps_notify_thread for cleanup?
Update the value in the hash table to -1 and emit a close and remove
from the hash table if the value is -1?
We could also keep a local list of fd in apps_notify_thread and use it for
cleanup instead of relying on ust_ust_app_by_notify_sock.
I'm not sure what is the best/elegant solution here. I am not a fan of
the current solution but it working.
Obviously this commit will be reworded and modified accordingly.
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
---
src/bin/lttng-sessiond/main.c | 55 ++++++++++++++++++++++++-------------------
1 file changed, 31 insertions(+), 24 deletions(-)
diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 4a2a661f..216d0da6 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -6209,16 +6209,6 @@ int main(int argc, char **argv)
}
notification_thread_running = true;
- /* Create thread to manage application notify socket */
- ret = pthread_create(&apps_notify_thread, default_pthread_attr(),
- ust_thread_manage_notify, (void *) NULL);
- if (ret) {
- errno = ret;
- PERROR("pthread_create notify");
- retval = -1;
- stop_threads();
- goto exit_apps_notify;
- }
/* Create thread to manage application socket */
ret = pthread_create(&apps_thread, default_pthread_attr(),
@@ -6231,6 +6221,17 @@ int main(int argc, char **argv)
goto exit_apps;
}
+ /* Create thread to manage application notify socket */
+ ret = pthread_create(&apps_notify_thread, default_pthread_attr(),
+ ust_thread_manage_notify, (void *) NULL);
+ if (ret) {
+ errno = ret;
+ PERROR("pthread_create notify");
+ retval = -1;
+ stop_threads();
+ goto exit_apps_notify;
+ }
+
/* Create thread to dispatch registration */
ret = pthread_create(&dispatch_thread, default_pthread_attr(),
thread_dispatch_ust_registration, (void *) NULL);
@@ -6358,20 +6359,6 @@ exit_reg_apps:
}
exit_dispatch:
- /* Instruct the apps thread to quit */
- ret = notify_thread_pipe(thread_apps_teardown_trigger_pipe[1]);
- if (ret < 0) {
- ERR("write error on thread quit pipe");
- }
-
- ret = pthread_join(apps_thread, &status);
- if (ret) {
- errno = ret;
- PERROR("pthread_join apps");
- retval = -1;
- }
-
-exit_apps:
/* Instruct the apps_notify thread to quit */
ret = notify_thread_pipe(thread_apps_notify_teardown_trigger_pipe[1]);
if (ret < 0) {
@@ -6386,6 +6373,26 @@ exit_apps:
}
exit_apps_notify:
+ /*
+ * The barrier ensure that all previous resources, notify sockets in
+ * particular, are freed/closed.
+ */
+ rcu_barrier();
+
+ /* Instruct the apps thread to quit */
+ ret = notify_thread_pipe(thread_apps_teardown_trigger_pipe[1]);
+ if (ret < 0) {
+ ERR("write error on thread quit pipe");
+ }
+
+ ret = pthread_join(apps_thread, &status);
+ if (ret) {
+ errno = ret;
+ PERROR("pthread_join apps");
+ retval = -1;
+ }
+
+exit_apps:
exit_notification:
exit_health:
exit_init_data:
--
2.11.0
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