QThread::requestInterruption(): move qWarning() out of critical section

We do not touch anything mutex-protected in the path towards the qWarning(), so
the mutex lock is not needed. It may actually be harmful, since a message handler
may check isInterruptionRequested(), which would then deadlock.

Otherwise, we're just decreasing the size of the critical section — always a
worthwhile goal.

Change-Id: I26aa7e3dc087ff7efaccff1d4dc788ba00ba183f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/corelib/thread/qthread.cpp b/src/corelib/thread/qthread.cpp
index cad7a14017..20b1f01173 100644
--- a/src/corelib/thread/qthread.cpp
+++ b/src/corelib/thread/qthread.cpp
@@ -844,14 +844,14 @@ bool QThread::event(QEvent *event)
 
 void QThread::requestInterruption()
 {
-    Q_D(QThread);
-    QMutexLocker locker(&d->mutex);
-    if (!d->running || d->finished || d->isInFinish)
-        return;
     if (this == QCoreApplicationPrivate::theMainThread) {
         qWarning("QThread::requestInterruption has no effect on the main thread");
         return;
     }
+    Q_D(QThread);
+    QMutexLocker locker(&d->mutex);
+    if (!d->running || d->finished || d->isInFinish)
+        return;
     d->interruptionRequested = true;
 }