111 lines
3.6 KiB
Diff
111 lines
3.6 KiB
Diff
Fix a deadlock in Krita:
|
|
|
|
https://bugreports.qt.io/browse/QTBUG-83207
|
|
|
|
Patch copied from Qt bug tracker:
|
|
|
|
https://codereview.qt-project.org/c/qt/qtbase/+/296034
|
|
|
|
From 276fa8383a7535765be7182883ef4aade17ce013 Mon Sep 17 00:00:00 2001
|
|
From: Thiago Macieira <thiago.macieira@intel.com>
|
|
Date: Thu, 02 Apr 2020 12:08:41 -0300
|
|
Subject: [PATCH] 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 <volker.hilsheimer@qt.io>
|
|
Reviewed-by: David Faure <david.faure@kdab.com>
|
|
---
|
|
|
|
diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
|
|
index ddb053c..be9d92b 100644
|
|
--- a/src/corelib/plugin/qlibrary.cpp
|
|
+++ b/src/corelib/plugin/qlibrary.cpp
|
|
@@ -576,9 +576,7 @@
|
|
|
|
Q_TRACE(QLibraryPrivate_load_entry, fileName);
|
|
|
|
- mutex.lock();
|
|
bool ret = load_sys();
|
|
- mutex.unlock();
|
|
if (qt_debug_component()) {
|
|
if (ret) {
|
|
qDebug() << "loaded library" << fileName;
|
|
diff --git a/src/corelib/plugin/qlibrary_unix.cpp b/src/corelib/plugin/qlibrary_unix.cpp
|
|
index 017aa97..a5c72f8 100644
|
|
--- a/src/corelib/plugin/qlibrary_unix.cpp
|
|
+++ b/src/corelib/plugin/qlibrary_unix.cpp
|
|
@@ -123,6 +123,7 @@
|
|
|
|
bool QLibraryPrivate::load_sys()
|
|
{
|
|
+ QMutexLocker locker(&mutex);
|
|
QString attempt;
|
|
QFileSystemEntry fsEntry(fileName);
|
|
|
|
@@ -213,6 +214,7 @@
|
|
}
|
|
#endif
|
|
|
|
+ locker.unlock();
|
|
bool retry = true;
|
|
Handle hnd = nullptr;
|
|
for (int prefix = 0; retry && !hnd && prefix < prefixes.size(); prefix++) {
|
|
@@ -273,6 +275,8 @@
|
|
}
|
|
}
|
|
#endif
|
|
+
|
|
+ locker.relock();
|
|
if (!hnd) {
|
|
errorString = QLibrary::tr("Cannot load library %1: %2").arg(fileName, qdlerror());
|
|
}
|
|
diff --git a/src/corelib/plugin/qlibrary_win.cpp b/src/corelib/plugin/qlibrary_win.cpp
|
|
index 000bf76..ef58724 100644
|
|
--- a/src/corelib/plugin/qlibrary_win.cpp
|
|
+++ b/src/corelib/plugin/qlibrary_win.cpp
|
|
@@ -78,6 +78,7 @@
|
|
// fileName
|
|
//
|
|
// NB If it's a plugin we do not ever try the ".dll" extension
|
|
+ QMutexLocker locker(&mutex);
|
|
QStringList attempts;
|
|
|
|
if (pluginState != IsAPlugin)
|
|
@@ -95,6 +96,7 @@
|
|
attempts.prepend(QDir::rootPath() + fileName);
|
|
#endif
|
|
|
|
+ locker.unlock();
|
|
Handle hnd = nullptr;
|
|
for (const QString &attempt : qAsConst(attempts)) {
|
|
#ifndef Q_OS_WINRT
|
|
@@ -115,6 +117,7 @@
|
|
#ifndef Q_OS_WINRT
|
|
SetErrorMode(oldmode);
|
|
#endif
|
|
+ locker.relock();
|
|
if (!hnd) {
|
|
errorString = QLibrary::tr("Cannot load library %1: %2").arg(
|
|
QDir::toNativeSeparators(fileName), qt_error_string());
|