From 276fa8383a7535765be7182883ef4aade17ce013 Mon Sep 17 00:00:00 2001 From: Thiago Macieira Date: Thu, 2 Apr 2020 12:08:41 -0300 Subject: QLibrary: fix deadlock caused by fix to QTBUG-39642 Commit ae6f73e8566fa76470937aca737141183929a5ec inserted a mutex around the entire load_sys(). We had reasoed that deadlocks would only occur if the object creation in instance() recursed into its own instance(), which was already a bug. But we had forgotten that dlopen()/ LoadLibrary() executes initialization code from the module being loaded, which could cause a recursion back into the same QPluginLoader or QLibrary object. This recursion is benign because the module *is* loaded and dlopen()/LoadLibrary() returns the same handle. [ChangeLog][QtCore][QLibrary and QPluginLoader] Fixed a deadlock that would happen if the plugin or library being loaded has load-time initialization code (C++ global variables) that recursed back into the same QLibrary or QPluginLoader object. PS: QLibraryPrivate::loadPlugin() updates pluginState outside a mutex lock, so pluginState should be made an atomic variable. Once that is done, we'll only need locking the mutex to update errorString (no locking before loading). Fixes: QTBUG-83207 Task-number: QTBUG-39642 Change-Id: Ibdc95e9af7bd456a94ecfffd160209304e5ab2eb Reviewed-by: Volker Hilsheimer Reviewed-by: David Faure --- src/corelib/plugin/qlibrary.cpp | 2 -- 1 file changed, 2 deletions(-) (limited to 'src/corelib/plugin/qlibrary.cpp') diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp index ddb053c26f..be9d92b204 100644 --- a/src/corelib/plugin/qlibrary.cpp +++ b/src/corelib/plugin/qlibrary.cpp @@ -576,9 +576,7 @@ bool QLibraryPrivate::load() Q_TRACE(QLibraryPrivate_load_entry, fileName); - mutex.lock(); bool ret = load_sys(); - mutex.unlock(); if (qt_debug_component()) { if (ret) { qDebug() << "loaded library" << fileName; -- cgit v1.2.3