From 0033212b2f0facf676458cd9a217401bb203a4cf Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Tue, 21 Apr 2026 21:46:52 +1000
Subject: [PATCH] Qt: Don't read g_main_window on core thread

---
 src/core/system.cpp                      | 2 +-
 src/core/system_private.h                | 2 +-
 src/duckstation-qt/mainwindow.cpp        | 6 ++++--
 src/duckstation-qt/mainwindow.h          | 2 +-
 src/duckstation-qt/qthost.cpp            | 6 ++----
 src/duckstation-qt/qthost.h              | 1 +
 src/duckstation-regtest/regtest_host.cpp | 2 +-
 7 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/core/system.cpp b/src/core/system.cpp
index 11922bfb3..adde23c29 100644
--- a/src/core/system.cpp
+++ b/src/core/system.cpp
@@ -1496,7 +1496,7 @@ void System::ApplySettings(bool display_osd_messages)
   }
 
   CheckForSettingsChanges(old_settings);
-  Host::CheckForSettingsChanges(old_settings);
+  Host::OnSettingsReloaded();
 }
 
 void System::ReloadGameSettings(bool display_osd_messages)
diff --git a/src/core/system_private.h b/src/core/system_private.h
index d73c1c520..320026cc5 100644
--- a/src/core/system_private.h
+++ b/src/core/system_private.h
@@ -94,7 +94,7 @@ namespace Host {
 void LoadSettings(const SettingsInterface& si, std::unique_lock<std::mutex>& lock);
 
 /// Called after settings are updated.
-void CheckForSettingsChanges(const Settings& old_settings);
+void OnSettingsReloaded();
 
 /// Called when the VM is starting initialization, but has not been completed yet.
 void OnSystemStarting();
diff --git a/src/duckstation-qt/mainwindow.cpp b/src/duckstation-qt/mainwindow.cpp
index 714df84fd..4b86062a1 100644
--- a/src/duckstation-qt/mainwindow.cpp
+++ b/src/duckstation-qt/mainwindow.cpp
@@ -2606,6 +2606,7 @@ void MainWindow::connectSignals()
   connect(g_core_thread, &CoreThread::onReleaseRenderWindowRequested, this, &MainWindow::releaseRenderWindow);
   connect(g_core_thread, &CoreThread::onResizeRenderWindowRequested, this, &MainWindow::displayResizeRequested,
           Qt::BlockingQueuedConnection);
+  connect(g_core_thread, &CoreThread::settingsReloaded, this, &MainWindow::onSettingsReloaded);
   connect(g_core_thread, &CoreThread::systemStarting, this, &MainWindow::onSystemStarting);
   connect(g_core_thread, &CoreThread::systemStarted, this, &MainWindow::onSystemStarted);
   connect(g_core_thread, &CoreThread::systemStopping, this, &MainWindow::onSystemStopping);
@@ -2787,7 +2788,8 @@ SettingsWindow* MainWindow::getSettingsWindow()
   if (!m_settings_window)
   {
     m_settings_window = new SettingsWindow();
-    connect(m_settings_window, &SettingsWindow::debugOptionsVisibiltyChanged, this, &MainWindow::updateDebugMenuVisibility);
+    connect(m_settings_window, &SettingsWindow::debugOptionsVisibiltyChanged, this,
+            &MainWindow::updateDebugMenuVisibility);
   }
 
   return m_settings_window;
@@ -3132,7 +3134,7 @@ void MainWindow::requestExit(bool allow_confirm /* = true */)
   requestShutdown(allow_confirm, true, g_settings.save_state_on_exit, true, true, true, true);
 }
 
-void MainWindow::checkForSettingChanges()
+void MainWindow::onSettingsReloaded()
 {
 #ifdef _WIN32
   if (const bool disable_window_rounded_corners =
diff --git a/src/duckstation-qt/mainwindow.h b/src/duckstation-qt/mainwindow.h
index 3c5b4d888..d66e691f9 100644
--- a/src/duckstation-qt/mainwindow.h
+++ b/src/duckstation-qt/mainwindow.h
@@ -131,7 +131,6 @@ public:
   void requestShutdown(bool allow_confirm, bool allow_save_to_state, bool save_state, bool check_safety,
                        bool check_pause, bool exit_fullscreen_ui, bool quit_afterwards);
   void requestExit(bool allow_confirm = true);
-  void checkForSettingChanges();
   std::optional<WindowInfo> getWindowInfo();
 
   void recreate();
@@ -236,6 +235,7 @@ private:
   void onSettingsResetToDefault(bool system, bool controller);
   void updateDebugMenuVisibility();
 
+  void onSettingsReloaded();
   void onSystemStarting();
   void onSystemStarted();
   void onSystemStopping();
diff --git a/src/duckstation-qt/qthost.cpp b/src/duckstation-qt/qthost.cpp
index 97686d4ab..8a2eb018f 100644
--- a/src/duckstation-qt/qthost.cpp
+++ b/src/duckstation-qt/qthost.cpp
@@ -865,11 +865,9 @@ void Host::LoadSettings(const SettingsInterface& si, std::unique_lock<std::mutex
 {
 }
 
-void Host::CheckForSettingsChanges(const Settings& old_settings)
+void Host::OnSettingsReloaded()
 {
-  // NOTE: emu thread, push to UI thread
-  if (g_main_window)
-    QMetaObject::invokeMethod(g_main_window, &MainWindow::checkForSettingChanges, Qt::QueuedConnection);
+  emit g_core_thread->settingsReloaded();
 }
 
 void CoreThread::setDefaultSettings(bool host, bool system, bool controller)
diff --git a/src/duckstation-qt/qthost.h b/src/duckstation-qt/qthost.h
index 837c0002e..2c56739cb 100644
--- a/src/duckstation-qt/qthost.h
+++ b/src/duckstation-qt/qthost.h
@@ -104,6 +104,7 @@ Q_SIGNALS:
   void errorReported(const QString& title, const QString& message);
   void statusMessage(const QString& message);
   void settingsResetToDefault(bool host, bool system, bool controller);
+  void settingsReloaded();
   void systemStarting();
   void systemStarted();
   void systemStopping();
diff --git a/src/duckstation-regtest/regtest_host.cpp b/src/duckstation-regtest/regtest_host.cpp
index a506b41ba..89ec8881a 100644
--- a/src/duckstation-regtest/regtest_host.cpp
+++ b/src/duckstation-regtest/regtest_host.cpp
@@ -205,7 +205,7 @@ void Host::LoadSettings(const SettingsInterface& si, std::unique_lock<std::mutex
 {
 }
 
-void Host::CheckForSettingsChanges(const Settings& old_settings)
+void Host::OnSettingsReloaded()
 {
 }