From 0c64d1b2c6e5e0951675ad9b22294db4a10741c7 Mon Sep 17 00:00:00 2001
From: Pankaj Pandey <pankaj86@gmail.com>
Date: Thu, 1 May 2014 19:58:03 +0530
Subject: PYSIDE-164: Fix possible deadlock on signal connect/emit

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>
---
 PySide/QtCore/glue/qobject_connect.cpp | 19 ++++++++++++++---
 libpyside/pysidemetafunction.cpp       |  2 ++
 tests/QtCore/CMakeLists.txt            |  1 +
 tests/QtCore/bug_PYSIDE-164.py         | 39 ++++++++++++++++++++++++++++++++++
 4 files changed, 58 insertions(+), 3 deletions(-)
 create mode 100644 tests/QtCore/bug_PYSIDE-164.py

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);
 
diff --git a/libpyside/pysidemetafunction.cpp b/libpyside/pysidemetafunction.cpp
index 3a7d86ba7..98ce9366c 100644
--- a/libpyside/pysidemetafunction.cpp
+++ b/libpyside/pysidemetafunction.cpp
@@ -198,7 +198,9 @@ bool call(QObject* self, int methodIndex, PyObject* args, PyObject** retVal)
 
     bool ok = i == numArgs;
     if (ok) {
+        Py_BEGIN_ALLOW_THREADS
         QMetaObject::metacall(self, QMetaObject::InvokeMetaMethod, method.methodIndex(), methArgs);
+        Py_END_ALLOW_THREADS
 
         if (retVal) {
             if (methArgs[0]) {
diff --git a/tests/QtCore/CMakeLists.txt b/tests/QtCore/CMakeLists.txt
index a8609de50..13567b351 100644
--- a/tests/QtCore/CMakeLists.txt
+++ b/tests/QtCore/CMakeLists.txt
@@ -28,6 +28,7 @@ PYSIDE_TEST(bug_1031.py)
 PYSIDE_TEST(bug_1063.py)
 PYSIDE_TEST(bug_1069.py)
 PYSIDE_TEST(bug_PYSIDE-42.py)
+PYSIDE_TEST(bug_PYSIDE-164.py)
 PYSIDE_TEST(blocking_signals_test.py)
 PYSIDE_TEST(classinfo_test.py)
 PYSIDE_TEST(child_event_test.py)
diff --git a/tests/QtCore/bug_PYSIDE-164.py b/tests/QtCore/bug_PYSIDE-164.py
new file mode 100644
index 000000000..53a1bd6c2
--- /dev/null
+++ b/tests/QtCore/bug_PYSIDE-164.py
@@ -0,0 +1,39 @@
+from PySide.QtCore import QCoreApplication, QEventLoop, QObject, Qt, QThread, QTimer, SIGNAL
+import unittest
+
+
+class Emitter(QThread):
+    def __init__(self):
+        QThread.__init__(self)
+
+    def run(self):
+        print "Before emit."
+        self.emit(SIGNAL("signal(int)"), 0)
+        print "After emit."
+
+class Receiver(QObject):
+    def __init__(self, eventloop):
+        QObject.__init__(self)
+        self.eventloop = eventloop
+
+    def receive(self, number):
+        print "Received number: %d" % number
+        self.eventloop.exit(0)
+
+
+class TestBugPYSIDE164(unittest.TestCase):
+
+    def testBlockingSignal(self):
+        app = QCoreApplication.instance() or QCoreApplication([])
+        eventloop = QEventLoop()
+        emitter = Emitter()
+        receiver = Receiver(eventloop)
+        emitter.connect(emitter, SIGNAL("signal(int)"),
+                        receiver.receive, Qt.BlockingQueuedConnection)
+        emitter.start()
+        retval = eventloop.exec_()
+        emitter.wait()
+        self.assertEqual(retval, 0)
+
+if __name__ == '__main__':
+    unittest.main()
-- 
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