From ddf9883f8d00dcdfd908b38c60114a06ce8af185 Mon Sep 17 00:00:00 2001 From: Kent Hansen Date: Wed, 16 Nov 2011 11:24:18 +0100 Subject: [PATCH] Change destruction order to avoid accessing deleted GL resources MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This commit fixes a crash when a QQuickCanvas containing a Text item is destroyed. 202127f860208c21145e05685bc54219e1655dbd in qtbase fixed a resource leak with QOpenGLMultiGroupSharedResource; resources were not cleaned up correctly when the associated GL context (group) was destroyed. This exposed a bug where QSGDefaultDistanceFieldGlyphCache (used for Text items) relied on that leakage. In particular, the glyph cache stores a pointer to a GL resource that it doesn't own (m_textureData). If the GL context is deleted and there are no other contexts in the group, the group and its resources will be deleted. Subsequently, if the glyph cache accesses the resource pointer when the Text node is destroyed (via QSGDefaultDistanceFieldGlyphCache::releaseGlyphs()), we crash. The GL context is deleted when QQuickCanvasPlainRenderLoop is destroyed. By moving the deletion of the render loop object to the end of QQuickCanvas destructor, the canvas nodes get a chance to clean up the resources they use _before_ the resources are deleted. Task-number: QTBUG-22754 Change-Id: Ie8de19a139b4631a16203e63e731feed3d8d64cf Reviewed-by: Aaron Kennedy Reviewed-by: Samuel Rødal --- src/declarative/items/qquickcanvas.cpp | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/src/declarative/items/qquickcanvas.cpp b/src/declarative/items/qquickcanvas.cpp index b433e02..383b552 100644 --- a/src/declarative/items/qquickcanvas.cpp +++ b/src/declarative/items/qquickcanvas.cpp @@ -863,11 +863,8 @@ QQuickCanvas::~QQuickCanvas() updatePaintNode(), so disconnect them before starting the shutdown */ disconnect(d->context->renderer(), SIGNAL(sceneGraphChanged()), this, SLOT(maybeUpdate())); - if (d->thread->isRunning()) { + if (d->thread->isRunning()) d->thread->stopRendering(); - delete d->thread; - d->thread = 0; - } // ### should we change ~QQuickItem to handle this better? // manually cleanup for the root item (item destructor only handles these when an item is parented) @@ -878,6 +875,8 @@ QQuickCanvas::~QQuickCanvas() delete d->rootItem; d->rootItem = 0; d->cleanupNodes(); + + delete d->thread; d->thread = 0; } /*! -- 2.7.4