1 files changed, 20 insertions, 8 deletions
diff --git a/src/corelib/time/qtimezoneprivate_tz.cpp b/src/corelib/time/qtimezoneprivate_tz.cpp
index b1611d7ddb..55914cc7da 100644
--- a/src/corelib/time/qtimezoneprivate_tz.cpp
+++ b/src/corelib/time/qtimezoneprivate_tz.cpp
@@ -42,6 +42,7 @@
 #include "qtimezone.h"
 #include "qtimezoneprivate_p.h"
 #include "private/qlocale_tools_p.h"
+#include "private/qlocking_p.h"
 
 #include <QtCore/QDataStream>
 #include <QtCore/QDateTime>
@@ -62,6 +63,10 @@
 
 QT_BEGIN_NAMESPACE
 
+#if QT_CONFIG(icu)
+static QBasicMutex s_icu_mutex;
+#endif
+
 /*
     Private
 
@@ -654,14 +659,8 @@ static QVector<QTimeZonePrivate::Data> calculatePosixTransitions(const QByteArra
 
 // Create the system default time zone
 QTzTimeZonePrivate::QTzTimeZonePrivate()
+    : QTzTimeZonePrivate(staticSystemTimeZoneId())
 {
-    init(systemTimeZoneId());
-}
-
-// Create a named time zone
-QTzTimeZonePrivate::QTzTimeZonePrivate(const QByteArray &ianaId)
-{
-    init(ianaId);
 }
 
 QTzTimeZonePrivate::~QTzTimeZonePrivate()
@@ -670,6 +669,9 @@ QTzTimeZonePrivate::~QTzTimeZonePrivate()
 
 QTzTimeZonePrivate *QTzTimeZonePrivate::clone() const
 {
+#if QT_CONFIG(icu)
+    const auto lock = qt_scoped_lock(s_icu_mutex);
+#endif
     return new QTzTimeZonePrivate(*this);
 }
 
@@ -872,7 +874,8 @@ QTzTimeZoneCacheEntry QTzTimeZoneCache::fetchEntry(const QByteArray &ianaId)
     return ret;
 }
 
-void QTzTimeZonePrivate::init(const QByteArray &ianaId)
+// Create a named time zone
+QTzTimeZonePrivate::QTzTimeZonePrivate(const QByteArray &ianaId)
 {
     static QTzTimeZoneCache tzCache;
     auto entry = tzCache.fetchEntry(ianaId);
@@ -913,12 +916,14 @@ QString QTzTimeZonePrivate::displayName(qint64 atMSecsSinceEpoch,
                                         const QLocale &locale) const
 {
 #if QT_CONFIG(icu)
+    auto lock = qt_unique_lock(s_icu_mutex);
     if (!m_icu)
         m_icu = new QIcuTimeZonePrivate(m_id);
     // TODO small risk may not match if tran times differ due to outdated files
     // TODO Some valid TZ names are not valid ICU names, use translation table?
     if (m_icu->isValid())
         return m_icu->displayName(atMSecsSinceEpoch, nameType, locale);
+    lock.unlock();
 #else
     Q_UNUSED(nameType)
     Q_UNUSED(locale)
@@ -932,12 +937,14 @@ QString QTzTimeZonePrivate::displayName(QTimeZone::TimeType timeType,
                                         const QLocale &locale) const
 {
 #if QT_CONFIG(icu)
+    auto lock = qt_unique_lock(s_icu_mutex);
     if (!m_icu)
         m_icu = new QIcuTimeZonePrivate(m_id);
     // TODO small risk may not match if tran times differ due to outdated files
     // TODO Some valid TZ names are not valid ICU names, use translation table?
     if (m_icu->isValid())
         return m_icu->displayName(timeType, nameType, locale);
+    lock.unlock();
 #else
     Q_UNUSED(timeType)
     Q_UNUSED(nameType)
@@ -1285,6 +1292,11 @@ private:
 
 QByteArray QTzTimeZonePrivate::systemTimeZoneId() const
 {
+    return staticSystemTimeZoneId();
+}
+
+QByteArray QTzTimeZonePrivate::staticSystemTimeZoneId()
+{
     // Check TZ env var first, if not populated try find it
     QByteArray ianaId = qgetenv("TZ");