PYSIDE-164: Fix possible deadlock on signal connect/emitps-4.8-head

Signal connect/emit acquire a lock on the QObject, and can
happen from python code (which has acquired the GIL) or
internal QtCode (without acquiring the GIL).
So we always need to release the GIL to prevent out-of-order
acquisition of the locks causing deadlock.

Change-Id: I1cf47a73c2b60627e322d8ef3fa4c3efdebd4c02
Reviewed-by: John Ehresman <jpe@wingware.com>

1 files changed, 16 insertions, 3 deletions

diff --git a/PySide/QtCore/glue/qobject_connect.cpp b/PySide/QtCore/glue/qobject_connect.cpp
index 96bcfb227..f7bb5faaf 100644
--- a/PySide/QtCore/glue/qobject_connect.cpp
+++ b/PySide/QtCore/glue/qobject_connect.cpp
@@ -61,7 +61,11 @@ static bool qobjectConnect(QObject* source, const char* signal, QObject* receive
     bool isSignal = PySide::Signal::isQtSignal(slot);
     slot++;
     PySide::SignalManager::registerMetaMethod(receiver, slot, isSignal ? QMetaMethod::Signal : QMetaMethod::Slot);
-    return QObject::connect(source, signal - 1, receiver, slot - 1, type);
+    bool connected;
+    Py_BEGIN_ALLOW_THREADS
+    connected = QObject::connect(source, signal - 1, receiver, slot - 1, type);
+    Py_END_ALLOW_THREADS
+    return connected;
 }
 
 static bool qobjectConnectCallback(QObject* source, const char* signal, PyObject* callback, Qt::ConnectionType type)
@@ -109,7 +113,11 @@ static bool qobjectConnectCallback(QObject* source, const char* signal, PyObject
             return false;
         }
     }
-    if (QMetaObject::connect(source, signalIndex, receiver, slotIndex, type)) {
+    bool connected;
+    Py_BEGIN_ALLOW_THREADS
+    connected = QMetaObject::connect(source, signalIndex, receiver, slotIndex, type);
+    Py_END_ALLOW_THREADS
+    if (connected) {
         if (usingGlobalReceiver)
             signalManager.notifyGlobalReceiver(receiver);
         #ifndef AVOID_PROTECTED_HACK
@@ -151,7 +159,12 @@ static bool qobjectDisconnectCallback(QObject* source, const char* signal, PyObj
 
     slotIndex = metaObject->indexOfSlot(callbackSig);
 
-    if (QMetaObject::disconnectOne(source, signalIndex, receiver, slotIndex)) {
+    bool disconnected;
+    Py_BEGIN_ALLOW_THREADS
+    disconnected = QMetaObject::disconnectOne(source, signalIndex, receiver, slotIndex);
+    Py_END_ALLOW_THREADS
+
+    if (disconnected) {
         if (usingGlobalReceiver)
             signalManager.releaseGlobalReceiver(source, receiver);