From e7665fd8e41176db517465b7732d53e3e29be876 Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Date: Sun, 13 Jul 2014 16:22:49 +0200
Subject: [PATCH] Revert "QRegularExpression: lock a mutex only if there's
 actual work to do"

Blunder -- two threads may step into this method together,
both see not studied, and both study (with one leaking its study data).

This reverts commit 5fbd787cf9a72621d66604a4898f06ea4365226e.

Change-Id: Ia746925abcad1e43adf4f6f1d495b018de022b07
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
---
 src/corelib/tools/qregularexpression.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/corelib/tools/qregularexpression.cpp b/src/corelib/tools/qregularexpression.cpp
index 4babfe1e19..259cfaba7e 100644
--- a/src/corelib/tools/qregularexpression.cpp
+++ b/src/corelib/tools/qregularexpression.cpp
@@ -1149,11 +1149,11 @@ void QRegularExpressionPrivate::optimizePattern(OptimizePatternOption option)
 {
     Q_ASSERT(compiledPattern);
 
+    QMutexLocker lock(&mutex);
+
     if (studyData.load()) // already optimized
         return;
 
-    QMutexLocker lock(&mutex);
-
     if ((option == LazyOptimizeOption) && (++usedCount != qt_qregularexpression_optimize_after_use_count))
         return;