wayland: Move ownership of the libinput thread to InputRedirection

When libinput tears down, it may access the Session object. This change
re-jitters the shut down logic so the Session object is guaranteed to be
valid when libinput stuff gets destroyed.

BUG: 442104

src/input.cpp

@@ -55,6 +55,7 @@
 #include <KScreenLocker/KsldApp>
 // Qt
 #include <QKeyEvent>
+#include <QThread>
 #include <qpa/qwindowsysteminterface.h>
 
 #include <xkbcommon/xkbcommon.h>
@@ -2134,6 +2135,14 @@ InputRedirection::InputRedirection(QObject *parent)
 
 InputRedirection::~InputRedirection()
 {
+    if (m_libInput) {
+        m_libInput->deleteLater();
+
+        m_libInputThread->quit();
+        m_libInputThread->wait();
+        delete m_libInputThread;
+    }
+
     s_self = nullptr;
     qDeleteAll(m_filters);
     qDeleteAll(m_spies);
@@ -2374,8 +2383,15 @@ void InputRedirection::setupLibInput()
     if (m_libInput) {
         return;
     }
+
+    m_libInputThread = new QThread();
+    m_libInputThread->setObjectName(QStringLiteral("libinput-connection"));
+    m_libInputThread->start();
+
     LibInput::Connection *conn = LibInput::Connection::create(this);
     m_libInput = conn;
+    m_libInput->moveToThread(m_libInputThread);
+
     if (conn) {
 
         if (waylandServer()) {

src/input.h

@@ -326,6 +326,7 @@ private:
     GlobalShortcutsManager *m_shortcuts;
 
     LibInput::Connection *m_libInput = nullptr;
+    QThread *m_libInputThread = nullptr;
 
     WindowSelectorFilter *m_windowSelector = nullptr;
 

src/libinput/connection.cpp

@@ -31,7 +31,6 @@
 #include <QDBusPendingCall>
 #include <QMutexLocker>
 #include <QSocketNotifier>
-#include <QThread>
 
 #include <libinput.h>
 #include <cmath>
@@ -81,7 +80,6 @@ Q_SIGNALS:
 };
 
 Connection *Connection::s_self = nullptr;
-QPointer<QThread> Connection::s_thread;
 
 static ConnectionAdaptor *s_adaptor = nullptr;
 static Context *s_context = nullptr;
@@ -107,16 +105,6 @@ Connection::Connection(QObject *parent)
     // only here to fix build, using will crash, BUG 343529
 }
 
-void Connection::createThread()
-{
-    if (s_thread) {
-        return;
-    }
-    s_thread = new QThread();
-    s_thread->setObjectName(QStringLiteral("libinput-connection"));
-    s_thread->start();
-}
-
 Connection *Connection::create(QObject *parent)
 {
     Q_ASSERT(!s_self);
@@ -141,12 +129,7 @@ Connection *Connection::create(QObject *parent)
             return nullptr;
         }
     }
-    Connection::createThread();
     s_self = new Connection(s_context);
-    s_self->moveToThread(s_thread);
-    QObject::connect(s_thread, &QThread::finished, s_self, &QObject::deleteLater);
-    QObject::connect(s_thread, &QThread::finished, s_thread, &QObject::deleteLater);
-    QObject::connect(parent, &QObject::destroyed, s_thread, &QThread::quit);
     if (!s_adaptor) {
         s_adaptor = new ConnectionAdaptor(s_self);
     }
@@ -333,7 +316,7 @@ void Connection::processEvents()
         switch (event->type()) {
             case LIBINPUT_EVENT_DEVICE_ADDED: {
                 auto device = new Device(event->nativeDevice());
-                device->moveToThread(s_thread);
+                device->moveToThread(thread());
                 m_devices << device;
                 if (device->isKeyboard()) {
                     m_keyboard++;

src/libinput/connection.h

@@ -87,8 +87,6 @@ public:
 
     void updateLEDs(KWin::Xkb::LEDs leds);
 
-    static void createThread();
-
 Q_SIGNALS:
     void keyChanged(quint32 key, KWin::InputRedirection::KeyboardKeyState, quint32 time, KWin::LibInput::Device *device);
     void pointerButtonChanged(quint32 button, KWin::InputRedirection::PointerButtonState state, quint32 time, KWin::LibInput::Device *device);
@@ -163,7 +161,6 @@ private:
     Xkb::LEDs m_leds;
 
     KWIN_SINGLETON(Connection)
-    static QPointer<QThread> s_thread;
 };
 
 }