[partition] Lock the bootloader model during reset

- Try to avoid races between resetting the model and getting
   data from it for the UI.

src/modules/partition/core/BootLoaderModel.cpp

@@ -69,6 +69,16 @@ BootLoaderModel::update()
 {
     beginResetModel();
     blockSignals( true );
+    updateInternal();
+    blockSignals( false );
+    endResetModel();
+}
+
+
+void
+BootLoaderModel::updateInternal()
+{
+    QMutexLocker lock(&m_lock);
     clear();
     createMbrItems();
 
@@ -113,14 +123,13 @@ BootLoaderModel::update()
             createBootLoaderItem( tr( "Do not install a boot loader" ), QString(), false )
         );
     }
-    blockSignals( false );
-    endResetModel();
 }
 
 
 QVariant
 BootLoaderModel::data( const QModelIndex& index, int role ) const
 {
+    QMutexLocker lock(&m_lock);
     if ( role == Qt::DisplayRole )
     {
         QString displayRole = QStandardItemModel::data( index, Qt::DisplayRole ).toString();

src/modules/partition/core/BootLoaderModel.h

@@ -19,8 +19,9 @@
 #ifndef BOOTLOADERMODEL_H
 #define BOOTLOADERMODEL_H
 
-#include <QStandardItemModel>
 #include <QList>
+#include <QMutex>
+#include <QStandardItemModel>
 
 class Device;
 
@@ -51,10 +52,14 @@ public:
 
     QVariant data( const QModelIndex& index, int role = Qt::DisplayRole ) const override;
 
+    using DeviceList = QList< Device* >;
+
 private:
-    QList< Device* > m_devices;
+    DeviceList m_devices;
+    mutable QMutex m_lock;
 
     void createMbrItems();
+    void updateInternal();
 };
 
 #endif /* BOOTLOADERMODEL_H */