3 files changed, 55 insertions, 13 deletions

diff --git a/src/dbus/qdbusabstractinterface.cpp b/src/dbus/qdbusabstractinterface.cpp
index 0f097517b7..d63a317612 100644
--- a/src/dbus/qdbusabstractinterface.cpp
+++ b/src/dbus/qdbusabstractinterface.cpp
@@ -35,6 +35,7 @@
 #include "qdbusabstractinterface.h"
 #include "qdbusabstractinterface_p.h"
 
+#include <qcoreapplication.h>
 #include <qthread.h>
 
 #include "qdbusargument.h"
@@ -51,6 +52,29 @@
 
 QT_BEGIN_NAMESPACE
 
+namespace {
+// ### Qt6: change to a regular QEvent (customEvent)
+// We need to use a QMetaCallEvent here because we can't override customEvent() in
+// Qt 5. Since QDBusAbstractInterface is meant to be derived from, the vtables of
+// classes in generated code will have a pointer to QObject::customEvent instead
+// of to QDBusAbstractInterface::customEvent.
+// See solution in Patch Set 1 of this change in the Qt Gerrit servers.
+// (https://codereview.qt-project.org/#/c/126384/1)
+class DisconnectRelayEvent : public QMetaCallEvent
+{
+public:
+    DisconnectRelayEvent(QObject *sender, const QMetaMethod &m)
+        : QMetaCallEvent(0, 0, Q_NULLPTR, sender, m.methodIndex())
+    {}
+
+    void placeMetaCall(QObject *object) Q_DECL_OVERRIDE
+    {
+        QDBusAbstractInterface *iface = static_cast<QDBusAbstractInterface *>(object);
+        QDBusAbstractInterfacePrivate::finishDisconnectNotify(iface, signalId());
+    }
+};
+}
+
 static QDBusError checkIfValid(const QString &service, const QString &path,
                                const QString &interface, bool isDynamic, bool isPeer)
 {
@@ -604,22 +628,38 @@ void QDBusAbstractInterface::disconnectNotify(const QMetaMethod &signal)
     if (!d->isValid)
         return;
 
+    // disconnection is just resource freeing, so it can be delayed;
+    // let's do that later, after all the QObject mutexes have been unlocked.
+    QCoreApplication::postEvent(this, new DisconnectRelayEvent(this, signal));
+}
+
+/*!
+    \internal
+    Continues the disconnect notification from above.
+*/
+void QDBusAbstractInterfacePrivate::finishDisconnectNotify(QDBusAbstractInterface *ptr, int signalId)
+{
+    QDBusAbstractInterfacePrivate *d = ptr->d_func();
     QDBusConnectionPrivate *conn = d->connectionPrivate();
-    if (conn && signal.isValid() && !isSignalConnected(signal))
-        return conn->disconnectRelay(d->service, d->path, d->interface,
-                                     this, signal);
     if (!conn)
         return;
 
-    // wildcard disconnecting, we need to figure out which of our signals are
-    // no longer connected to anything
-    const QMetaObject *mo = metaObject();
-    int midx = QObject::staticMetaObject.methodCount();
-    const int end = mo->methodCount();
-    for ( ; midx < end; ++midx) {
-        QMetaMethod mm = mo->method(midx);
-        if (mm.methodType() == QMetaMethod::Signal && !isSignalConnected(mm))
-            conn->disconnectRelay(d->service, d->path, d->interface, this, mm);
+    const QMetaObject *mo = ptr->metaObject();
+    QMetaMethod signal = signalId >= 0 ? mo->method(signalId) : QMetaMethod();
+    if (signal.isValid()) {
+        if (!ptr->isSignalConnected(signal))
+            return conn->disconnectRelay(d->service, d->path, d->interface,
+                                         ptr, signal);
+    } else {
+        // wildcard disconnecting, we need to figure out which of our signals are
+        // no longer connected to anything
+        int midx = QObject::staticMetaObject.methodCount();
+        const int end = mo->methodCount();
+        for ( ; midx < end; ++midx) {
+            QMetaMethod mm = mo->method(midx);
+            if (mm.methodType() == QMetaMethod::Signal && !ptr->isSignalConnected(mm))
+                conn->disconnectRelay(d->service, d->path, d->interface, ptr, mm);
+        }
     }
 }
 
diff --git a/src/dbus/qdbusabstractinterface_p.h b/src/dbus/qdbusabstractinterface_p.h
index 1ce457d94b..1d9290b746 100644
--- a/src/dbus/qdbusabstractinterface_p.h
+++ b/src/dbus/qdbusabstractinterface_p.h
@@ -91,6 +91,8 @@ public:
     { return QDBusConnectionPrivate::d(connection); }
 
     void _q_serviceOwnerChanged(const QString &name, const QString &oldOwner, const QString &newOwner);
+
+    static void finishDisconnectNotify(QDBusAbstractInterface *iface, int signalId);
 };
 
 QT_END_NAMESPACE
diff --git a/src/dbus/qdbusintegrator.cpp b/src/dbus/qdbusintegrator.cpp
index 7203f05a9b..c465706913 100644
--- a/src/dbus/qdbusintegrator.cpp
+++ b/src/dbus/qdbusintegrator.cpp
@@ -2278,7 +2278,7 @@ void QDBusConnectionPrivate::disconnectRelay(const QString &service,
     sig.append(signal.methodSignature());
     if (!prepareHook(hook, key, service, path, interface, QString(), QStringList(), receiver, sig,
                      QDBusAbstractInterface::staticMetaObject.methodCount(), true))
-        return;                 // don't connect
+        return;                 // don't disconnect
 
     Q_ASSERT(thread() != QThread::currentThread());
     emit signalNeedsDisconnecting(key, hook);