path: root/tests
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authorMÃ¥rten Nordheim <>2021-03-05 14:33:01 +0100
committerQt Cherry-pick Bot <>2021-03-25 10:04:55 +0000
commit955ce882f7c94f6085e26ef3f987fbfa72a1a8d7 (patch)
tree7dc45bc147bebe618e1d21fc201d734a6cb7fb49 /tests
parent4dc30edb4becdc3c26f21aa145cafeed131ad131 (diff)
QEventDispatcher(Win): Always honor interrupted status to avoid races
There may be a race where e.g. thread 'B' is woken up by a queued invoke. At the same time thread 'A' asks 'B' to quit, which will set various atomics (some important ones are 'interrupt' in the dispatcher and 'exit' in the event loop), but it does _not_ try to send another wake since there is already an unhandled wake triggered by 'B' itself. Sadly 'B' reads the 'exit' atomic before 'A' updates it. Then, slightly before, 'B' sets 'interrupt' back to 0, 'A' write 1 to it, meaning 'A's interrupt is ignored. Then, since there is no interrupt, 'B' goes back to waiting for events, leaving the thread alive and running instead of quitting. Maybe this has unforeseen consequences (one consequence is that it will return and re-enter the event dispatcher once more, possible unnecessarily) Fixes: QTBUG-91539 Change-Id: Ie6f861f42ffddf4817d5c8af2d764abe9d9103c2 Reviewed-by: Alex Trotsenko <> Reviewed-by: Volker Hilsheimer <> Reviewed-by: Thiago Macieira <> (cherry picked from commit f274f91cebb0a4fd2ebe37bb3a605c47d6acd404) Reviewed-by: Qt Cherry-pick Bot <>
Diffstat (limited to 'tests')
1 files changed, 27 insertions, 0 deletions
diff --git a/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp b/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp
index fa5c78bceb..ac71e6b08c 100644
--- a/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp
+++ b/tests/auto/corelib/kernel/qeventdispatcher/tst_qeventdispatcher.cpp
@@ -69,6 +69,7 @@ private slots:
void processEventsOnlySendsQueuedEvents();
void postedEventsPingPong();
void eventLoopExit();
+ void interruptTrampling();
bool tst_QEventDispatcher::event(QEvent *e)
@@ -419,5 +420,31 @@ void tst_QEventDispatcher::eventLoopExit()
+// Based on QTBUG-91539: In the event dispatcher on Windows we overwrite the
+// interrupt once we start processing events (this pattern is also in the 'unix' dispatcher)
+// which would lead the dispatcher to accidentally ignore certain interrupts and,
+// as in the bug report, would not quit, leaving the thread alive and running.
+void tst_QEventDispatcher::interruptTrampling()
+ class WorkerThread : public QThread
+ {
+ void run() override {
+ auto dispatcher = eventDispatcher();
+ QVERIFY(dispatcher);
+ dispatcher->processEvents(QEventLoop::AllEvents);
+ QTimer::singleShot(0, [dispatcher]() {
+ dispatcher->wakeUp();
+ });
+ dispatcher->processEvents(QEventLoop::WaitForMoreEvents);
+ dispatcher->interrupt();
+ dispatcher->processEvents(QEventLoop::WaitForMoreEvents);
+ }
+ };
+ WorkerThread thread;
+ thread.start();
+ QVERIFY(thread.wait(1000));
+ QVERIFY(thread.isFinished());
#include "tst_qeventdispatcher.moc"