Fix two data races in QThread/QThreadData

* theMainThread is written by the main thread and read by
   QThreadData::~QThreadData() (any managed thread)

* QThreadData::thread is written by QThread::~QThread (in the parent thread)
  and read+written by QThreadData::~QThreadData (in the managed thread).
  This can happen because QThreadData is refcounted so the managed
  thread (which derefs it) races with the parent thread (which sets it to 0).

Change-Id: I72de793716391a0937254cda6b4328fcad5060c7
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/corelib/thread/qthreadstorage.cpp b/src/corelib/thread/qthreadstorage.cpp
index 05ab01cc54..37892233f3 100644
--- a/src/corelib/thread/qthreadstorage.cpp
+++ b/src/corelib/thread/qthreadstorage.cpp
@@ -121,7 +121,7 @@ void **QThreadStorageData::get() const
     DEBUG_MSG("QThreadStorageData: Returning storage %d, data %p, for thread %p",
           id,
           *v,
-          data->thread);
+          data->thread.load());
 
     return *v ? v : 0;
 }
@@ -143,7 +143,7 @@ void **QThreadStorageData::set(void *p)
         DEBUG_MSG("QThreadStorageData: Deleting previous storage %d, data %p, for thread %p",
                 id,
                 value,
-                data->thread);
+                data->thread.load());
 
         QMutexLocker locker(&destructorsMutex);
         DestructorMap *destr = destructors();
@@ -159,7 +159,7 @@ void **QThreadStorageData::set(void *p)
 
     // store new data
     value = p;
-    DEBUG_MSG("QThreadStorageData: Set storage %d for thread %p to %p", id, data->thread, p);
+    DEBUG_MSG("QThreadStorageData: Set storage %d for thread %p to %p", id, data->thread.load(), p);
     return &value;
 }