Fix: skip start trace for app that are already started.

When using trackers, call to ust_app_global_update
results in a call to ust_app_start_trace even if the ust app
trace was already enabled.

This resulted in error message from the app (-1024) complaining that the
tracing was already active on the app side.

  Error: Error starting tracing for app pid: 329376 (ret: -1024)
  ok 211 - Track command with opts: 0 -u --vpid 329376

A solution to this is to keep the enabled state inside the ua_sess and
skip the start trace if already enabled.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Change-Id: Ie4198245627e9f0426948489bc9ce24d8c813b08
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 823de94785c1a6d6964ed9b165f47d4690d59741..63bf4648b5b6f1ade155fdaaa92917515d6814cd 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -4347,6 +4347,11 @@ int ust_app_start_trace(struct ltt_ust_session *usess, struct ust_app *app)
                goto end;
        }
 
+       if (ua_sess->enabled) {
+               pthread_mutex_unlock(&ua_sess->lock);
+               goto end;
+       }
+
        /* Upon restart, we skip the setup, already done */
        if (ua_sess->started) {
                goto skip_setup;
@@ -4387,6 +4392,7 @@ skip_setup:
 
        /* Indicate that the session has been started once */
        ua_sess->started = 1;
+       ua_sess->enabled = 1;
 
        pthread_mutex_unlock(&ua_sess->lock);
 
@@ -4476,6 +4482,7 @@ int ust_app_stop_trace(struct ltt_ust_session *usess, struct ust_app *app)
        }
 
        health_code_update();
+       ua_sess->enabled = 0;
 
        /* Quiescent wait after stopping trace */
        pthread_mutex_lock(&app->sock_lock);