winrt: Proper guarding by readMutex

Commented its purpose and the guarded members for
readMutex.

Fixed places where guarded members were accessed without
using the mutex.

Use QMutexLocker instead of manually (un-)locking the
mutex.

Task-number: QTBUG-44357
Change-Id: I0d46f9592d5a9d1b52e73df961785a6f6c9e80be
Reviewed-by: David Faure <david.faure@kdab.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/network/socket/qnativesocketengine_winrt_p.h b/src/network/socket/qnativesocketengine_winrt_p.h
index 79530d57f1..c9a67ca5f4 100644
--- a/src/network/socket/qnativesocketengine_winrt_p.h
+++ b/src/network/socket/qnativesocketengine_winrt_p.h
@@ -215,12 +215,23 @@ private:
     Microsoft::WRL::ComPtr<ABI::Windows::Networking::Sockets::IStreamSocketListener> tcpListener;
     Microsoft::WRL::ComPtr<ABI::Windows::Foundation::IAsyncAction> connectOp;
     QVector<Microsoft::WRL::ComPtr<ABI::Windows::Foundation::IAsyncOperationWithProgress<ABI::Windows::Storage::Streams::IBuffer *, UINT32>>> pendingReadOps;
+
+    // Protected by readMutex. Written in handleReadyRead (native callback)
     QBuffer readBytes;
-    QMutex readMutex;
+
+    // In case of TCP readMutex protects readBytes and bytesAvailable. In case of UDP it is
+    // pendingDatagrams. They are written inside native callbacks (handleReadyRead and
+    // handleNewDatagrams/putIntoPendingDatagramsList)
+    mutable QMutex readMutex;
+
     bool emitOnNewDatagram;
+
+    // Protected by readMutex. Written in handleReadyRead (native callback)
     QAtomicInteger<int> bytesAvailable;
 
+    // Protected by readMutex. Written in handleNewDatagrams/putIntoPendingDatagramsList
     QList<WinRtDatagram> pendingDatagrams;
+
     QList<ABI::Windows::Networking::Sockets::IStreamSocket *> pendingConnections;
     QList<ABI::Windows::Networking::Sockets::IStreamSocket *> currentConnections;
     QEventLoop eventLoop;