From 52f29458d7d6cb379d28d84021819516723d9169 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@qt.io>
Date: Thu, 18 Jun 2020 09:53:06 +0200
Subject: pthreads: Try to abandon the GIL in case a thread was terminated

 When terminating a thread using QThread::terminate() via
(pthread_cancel(), QThread::run() is aborted and the lock is released,
but ~GilState() is still executed for some reason.

Add a cancel handler to the thread which tells GilState to abandon
the lock.

Fixes: PYSIDE-1282
Change-Id: I70abd42b5a2afd49aaa8cc5e8be0a92ed63f49d3
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>
---
 .../PySide2/QtCore/typesystem_core_common.xml      |  8 ++++++-
 sources/pyside2/PySide2/glue/qtcore.cpp            | 28 ++++++++++++++++++++++
 sources/shiboken2/libshiboken/gilstate.cpp         |  7 ++++++
 sources/shiboken2/libshiboken/gilstate.h           |  1 +
 4 files changed, 43 insertions(+), 1 deletion(-)

(limited to 'sources')

diff --git a/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml b/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml
index 26193a0aa..8294947ed 100644
--- a/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml
+++ b/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml
@@ -1460,9 +1460,15 @@
     <enum-type name="IteratorFlag" flags="IteratorFlags"/>
   </object-type>
   <object-type name="QThread">
+    <inject-code file="../glue/qtcore.cpp" class="native" position="beginning" snippet="qthread_pthread_cleanup"/>
     <enum-type name="Priority"/>
     <modify-function signature="currentThreadId()" remove="all"/>
-    <modify-function signature="run()" allow-thread="yes"/>
+    <modify-function signature="run()" allow-thread="yes">
+        <inject-code file="../glue/qtcore.cpp" class="native" position="beginning"
+                     snippet="qthread_pthread_cleanup_install"/>
+        <inject-code file="../glue/qtcore.cpp" class="native" position="end"
+                     snippet="qthread_pthread_cleanup_uninstall"/>
+    </modify-function>
     <modify-function signature="exec()" rename="exec_" allow-thread="yes"/>
     <modify-function signature="msleep(unsigned long)" allow-thread="yes"/>
     <modify-function signature="sleep(unsigned long)" allow-thread="yes"/>
diff --git a/sources/pyside2/PySide2/glue/qtcore.cpp b/sources/pyside2/PySide2/glue/qtcore.cpp
index 111e324b9..41ee743e7 100644
--- a/sources/pyside2/PySide2/glue/qtcore.cpp
+++ b/sources/pyside2/PySide2/glue/qtcore.cpp
@@ -1960,3 +1960,31 @@ PyTuple_SET_ITEM(%out, 0, %CONVERTTOPYTHON[%INTYPE_0](%in.first));
 PyTuple_SET_ITEM(%out, 1, %CONVERTTOPYTHON[%INTYPE_1](%in.second));
 return %out;
 // @snippet return-qpair
+
+// @snippet qthread_pthread_cleanup
+#ifdef Q_OS_UNIX
+#  include <stdio.h>
+#  include <pthread.h>
+static void qthread_pthread_cleanup(void *arg)
+{
+    // PYSIDE 1282: When terminating a thread using QThread::terminate()
+    // (pthread_cancel()), QThread::run() is aborted and the lock is released,
+    // but ~GilState() is still executed for some reason. Prevent it from
+    // releasing.
+    auto gil = reinterpret_cast<Shiboken::GilState *>(arg);
+    gil->abandon();
+}
+#endif // Q_OS_UNIX
+// @snippet qthread_pthread_cleanup
+
+// @snippet qthread_pthread_cleanup_install
+#ifdef Q_OS_UNIX
+pthread_cleanup_push(qthread_pthread_cleanup, &gil);
+#endif
+// @snippet qthread_pthread_cleanup_install
+
+// @snippet qthread_pthread_cleanup_uninstall
+#ifdef Q_OS_UNIX
+pthread_cleanup_pop(0);
+#endif
+// @snippet qthread_pthread_cleanup_uninstall
diff --git a/sources/shiboken2/libshiboken/gilstate.cpp b/sources/shiboken2/libshiboken/gilstate.cpp
index a59c6f01e..76a4d0e61 100644
--- a/sources/shiboken2/libshiboken/gilstate.cpp
+++ b/sources/shiboken2/libshiboken/gilstate.cpp
@@ -63,5 +63,12 @@ void GilState::release()
     }
 }
 
+// Abandon the lock: Only for special situations, like termination of a
+// POSIX thread (PYSIDE 1282).
+void GilState::abandon()
+{
+    m_locked = false;
+}
+
 } // namespace Shiboken
 
diff --git a/sources/shiboken2/libshiboken/gilstate.h b/sources/shiboken2/libshiboken/gilstate.h
index d22f688ba..fbf39ead0 100644
--- a/sources/shiboken2/libshiboken/gilstate.h
+++ b/sources/shiboken2/libshiboken/gilstate.h
@@ -57,6 +57,7 @@ public:
     GilState();
     ~GilState();
     void release();
+    void abandon();
 private:
     PyGILState_STATE m_gstate;
     bool m_locked = false;
-- 
cgit v1.2.3