diff options
| author | Thiago Macieira <thiago.macieira@intel.com> | 2016-12-26 14:23:39 -0200 |
|---|---|---|
| committer | Thiago Macieira <thiago.macieira@intel.com> | 2017-01-03 13:28:24 +0000 |
| commit | 9449325f2b234981a2ecc1b0a0bd6ec74f30ff6c (patch) | |
| tree | efa24eb387517e777cca85430f17f4f217aeb1ae | |
| parent | e2ab9322769856fb03ca1f0f24408a3abb8bd38a (diff) | |
Partially revert "Windows: stop using _beginthreadex on regular builds"
This pertially reverts commit 3ec57107cedb154f256e3ad001ea5475cc64fa94
and brings back the hack to prevent the DLL from being unloaded. It
should have been enough, but we've got reports that it's still causing
trouble. Since it causes not much harm to keep the DLL loaded (worst
case scenario is that QtDBus and QtCore remain loaded after a plugin
gets unloaded), we'll keep it.
Note: Microsoft is aware that their way of killing threads on process
exit is a flaw. See https://blogs.msdn.microsoft.com/oldnewthing/20070502-00/?p=27023/
Task-number: QTBUG-53031
Change-Id: I2962773739e34633b033fffd1493dce695b008c0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@qt.io>
| -rw-r--r-- | src/dbus/qdbusconnection.cpp | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/src/dbus/qdbusconnection.cpp b/src/dbus/qdbusconnection.cpp index f95cc3a15d..da7557d7e8 100644 --- a/src/dbus/qdbusconnection.cpp +++ b/src/dbus/qdbusconnection.cpp @@ -69,6 +69,10 @@ QT_BEGIN_NAMESPACE +#ifdef Q_OS_WIN +static void preventDllUnload(); +#endif + Q_GLOBAL_STATIC(QDBusConnectionManager, _q_manager) struct QDBusConnectionManager::ConnectionRequestData @@ -139,6 +143,10 @@ QDBusConnectionManager::QDBusConnectionManager() this, &QDBusConnectionManager::createServer, Qt::BlockingQueuedConnection); moveToThread(this); // ugly, don't do this in other projects +#ifdef Q_OS_WIN + // prevent the library from being unloaded on Windows. See comments in the function. + preventDllUnload(); +#endif defaultBuses[0] = defaultBuses[1] = Q_NULLPTR; start(); } @@ -1262,4 +1270,31 @@ QByteArray QDBusConnection::localMachineId() QT_END_NAMESPACE +#ifdef Q_OS_WIN +# include <qt_windows.h> + +QT_BEGIN_NAMESPACE +static void preventDllUnload() +{ + // Thread termination is really wacky on Windows. For some reason we don't + // understand, exiting from the thread may try to unload the DLL. Since the + // QDBusConnectionManager thread runs until the DLL is unloaded, we've got + // a deadlock: the main thread is waiting for the manager thread to exit, + // but the manager thread is attempting to acquire a lock to unload the DLL. + // + // We work around the issue by preventing the unload from happening in the + // first place. + // + // For this trick, see + // https://blogs.msdn.microsoft.com/oldnewthing/20131105-00/?p=2733 + + static HMODULE self; + GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | + GET_MODULE_HANDLE_EX_FLAG_PIN, + reinterpret_cast<const wchar_t *>(&self), // any address in this DLL + &self); +} +QT_END_NAMESPACE +#endif + #endif // QT_NO_DBUS |