From ca4d93d85ee446c5e30ec8e7814651e45cbf1218 Mon Sep 17 00:00:00 2001 From: Thiago Macieira Date: Thu, 12 Nov 2015 10:14:51 -0800 Subject: Stop unloading plugins in QPluginLoader and QFactoryLoader QPluginLoader hasn't unloaded in its destructor since Qt 5.0, but we missed the equivalent code in QFactoryLoader (which bypasses QPluginLoader). Besides, QPluginLoader::unload() was still doing unloading, which it won't anymore. Not unloading plugins is Qt's policy, as decided during the 5.0 development process and reaffirmed now in 5.6. This is due to static data in plugins leaking out and remaining in use past the unloading of the plugin, causing crashes. This does not affect QLibrary and QLibrary::unload(). Those are meant for non-Qt loadable modules, so unloading them may be safe. Task-number: QTBUG-49061 Discussed-on: http://lists.qt-project.org/pipermail/development/2015-November/023681.html Change-Id: I461e9fc7199748faa187ffff1416070f138df8db (cherry picked from commit 494376f980e96339b6f1eff7c41336ca4d853065) Discussed-again-on: http://lists.qt-project.org/pipermail/development/2016-October/027476.html Reviewed-by: Lars Knoll --- src/corelib/plugin/qfactoryloader.cpp | 6 ++++-- src/corelib/plugin/qpluginloader.cpp | 5 +++-- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/src/corelib/plugin/qfactoryloader.cpp b/src/corelib/plugin/qfactoryloader.cpp index dcf1b1a..b6558f5 100644 --- a/src/corelib/plugin/qfactoryloader.cpp +++ b/src/corelib/plugin/qfactoryloader.cpp @@ -208,10 +208,12 @@ void QFactoryLoader::update() ++keyUsageCount; } } - if (keyUsageCount || keys.isEmpty()) + if (keyUsageCount || keys.isEmpty()) { + library->setLoadHints(QLibrary::PreventUnloadHint); // once loaded, don't unload d->libraryList += library; - else + } else { library->release(); + } } } #else diff --git a/src/corelib/plugin/qpluginloader.cpp b/src/corelib/plugin/qpluginloader.cpp index 37f2368..0ea8280 100644 --- a/src/corelib/plugin/qpluginloader.cpp +++ b/src/corelib/plugin/qpluginloader.cpp @@ -148,6 +148,7 @@ QPluginLoader::QPluginLoader(const QString &fileName, QObject *parent) : QObject(parent), d(0), did_load(false) { setFileName(fileName); + setLoadHints(QLibrary::PreventUnloadHint); } /*! @@ -342,7 +343,7 @@ static QString locatePlugin(const QString& fileName) void QPluginLoader::setFileName(const QString &fileName) { #if defined(QT_SHARED) - QLibrary::LoadHints lh; + QLibrary::LoadHints lh = QLibrary::PreventUnloadHint; if (d) { lh = d->loadHints(); d->release(); @@ -391,7 +392,7 @@ Q_GLOBAL_STATIC(StaticPluginList, staticPluginList) \brief Give the load() function some hints on how it should behave. You can give hints on how the symbols in the plugin are - resolved. By default, none of the hints are set. + resolved. By default since Qt 5.7, QLibrary::PreventUnloadHint is set. See the documentation of QLibrary::loadHints for a complete description of how this property works. -- cgit v1.0-4-g1e03