From 275b7ee0f456328de870dcdc297871d4eb8cfff2 Mon Sep 17 00:00:00 2001
From: David Edmundson <kde@davidedmundson.co.uk>
Date: Wed, 20 Jun 2018 09:37:55 +0100
Subject: [PATCH] Workaround crash in Aurorae destruction

Summary:
Workaround QtBug-68997

Deleting of a RenderControl/render controlled window triggers deletion
of other queued deleted items, putting KWin in a corrupt state. See Qt
bug report.

Deleting this queued means we know we don't have anything else going on
in the stack which should make this somewhat safe.

BUG: 395346

Test Plan:
Couldn't reproduce original crash. Based purely on the incomplete backtrace and code reading

Set an Aurorae theme. Closed some windows. Things still worked as before

Reviewers: #kwin, #plasma, mart

Reviewed By: #kwin, #plasma, mart

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D13614
---
 plugins/kdecorations/aurorae/src/aurorae.cpp | 10 ++++------
 plugins/kdecorations/aurorae/src/aurorae.h   |  6 +++++-
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/plugins/kdecorations/aurorae/src/aurorae.cpp b/plugins/kdecorations/aurorae/src/aurorae.cpp
index 4c5879be2e..15266b7987 100644
--- a/plugins/kdecorations/aurorae/src/aurorae.cpp
+++ b/plugins/kdecorations/aurorae/src/aurorae.cpp
@@ -270,8 +270,6 @@ Decoration::~Decoration()
     if (m_context) {
         m_context->makeCurrent(m_offscreenSurface.data());
 
-        delete m_renderControl;
-        delete m_view.data();
         m_fbo.reset();
         delete m_item;
 
@@ -324,8 +322,8 @@ void Decoration::init()
         m_item->setParentItem(visualParent.value<QQuickItem*>());
         visualParent.value<QQuickItem*>()->setProperty("drawBackground", false);
     } else {
-        m_renderControl = new QQuickRenderControl(this);
-        m_view = new QQuickWindow(m_renderControl);
+        m_renderControl.reset(new QQuickRenderControl);
+        m_view = new QQuickWindow(m_renderControl.data());
         bool usingGL = m_view->rendererInterface()->graphicsApi() == QSGRendererInterface::OpenGL;
         m_view->setColor(Qt::transparent);
         m_view->setFlags(Qt::FramelessWindowHint);
@@ -392,8 +390,8 @@ void Decoration::init()
             }
             m_updateTimer->start();
         };
-        connect(m_renderControl, &QQuickRenderControl::renderRequested, this, requestUpdate);
-        connect(m_renderControl, &QQuickRenderControl::sceneChanged, this, requestUpdate);
+        connect(m_renderControl.data(), &QQuickRenderControl::renderRequested, this, requestUpdate);
+        connect(m_renderControl.data(), &QQuickRenderControl::sceneChanged, this, requestUpdate);
 
         m_item->setParentItem(m_view->contentItem());
 
diff --git a/plugins/kdecorations/aurorae/src/aurorae.h b/plugins/kdecorations/aurorae/src/aurorae.h
index 3b280990e6..80e477ba04 100644
--- a/plugins/kdecorations/aurorae/src/aurorae.h
+++ b/plugins/kdecorations/aurorae/src/aurorae.h
@@ -87,7 +87,11 @@ private:
     KWin::Borders *m_extendedBorders;
     KWin::Borders *m_padding;
     QString m_themeName;
-    QQuickRenderControl *m_renderControl = nullptr;
+
+    //workaround QtBug-68997
+    //deleting of a RenderControl/controlled window triggers deletion of other queued deleted items
+    //deleting this queued means we know we're not processing anything else at the same time and should minimise the damage
+    QScopedPointer<QQuickRenderControl, QScopedPointerDeleteLater> m_renderControl;
     QScopedPointer<QTimer> m_updateTimer;
     QScopedPointer<QOpenGLContext> m_context;
     QScopedPointer<QOffscreenSurface> m_offscreenSurface;