Fix crash at exit when tracing

The crash is caused by the cleanup sending trace messages when the
plugin has already been destroyed. Add shutdown callback to the plugin
to indicate this has happened. We can't use signals since that also
generetes trace event.

Pick-to: 6.5
Change-Id: I2e490fc51c2aaa97c240c1496a528a6ff6077bd0
Reviewed-by: Hatem ElKharashy <hatem.elkharashy@qt.io>
Reviewed-by: Janne Koskinen <janne.p.koskinen@qt.io>

1 files changed, 3 insertions, 7 deletions

diff --git a/src/corelib/tracing/qctf.cpp b/src/corelib/tracing/qctf.cpp
index 1dafa582d9..00a196c926 100644
--- a/src/corelib/tracing/qctf.cpp
+++ b/src/corelib/tracing/qctf.cpp
@@ -15,6 +15,7 @@ QT_BEGIN_NAMESPACE
 static bool s_initialized = false;
 static bool s_triedLoading = false;
 static bool s_prevent_recursion = false;
+static bool s_shutdown = false;
 static QCtfLib* s_plugin = nullptr;
 
 #if defined(Q_OS_ANDROID)
@@ -59,18 +60,13 @@ static bool loadPlugin(bool &retry)
     s_plugin = qobject_cast<QCtfLib *>(loader.instance());
     if (!s_plugin)
         return false;
-    QObject *obj = loader.instance();
-    if (obj) {
-        QObject::connect(obj, &QObject::destroyed, []() {
-            s_plugin = nullptr;
-        });
-    }
+    s_plugin->shutdown(&s_shutdown);
     return true;
 }
 
 static bool initialize()
 {
-    if (s_prevent_recursion)
+    if (s_shutdown || s_prevent_recursion)
         return false;
     if (s_initialized || s_triedLoading)
         return s_initialized;