wined3d: Lock wined3d mutex in wined3d_swapchain_decref().

dlls/d3d8/swapchain.c

@@ -74,9 +74,7 @@ static ULONG WINAPI d3d8_swapchain_Release(IDirect3DSwapChain8 *iface)
     {
         IDirect3DDevice8 *parent_device = swapchain->parent_device;
 
-        wined3d_mutex_lock();
         wined3d_swapchain_decref(swapchain->wined3d_swapchain);
-        wined3d_mutex_unlock();
 
         if (parent_device)
             IDirect3DDevice8_Release(parent_device);

dlls/d3d9/swapchain.c

@@ -124,9 +124,7 @@ static ULONG WINAPI d3d9_swapchain_Release(IDirect3DSwapChain9Ex *iface)
     {
         IDirect3DDevice9Ex *parent_device = swapchain->parent_device;
 
-        wined3d_mutex_lock();
         wined3d_swapchain_decref(swapchain->wined3d_swapchain);
-        wined3d_mutex_unlock();
 
         /* Release the device last, as it may cause the device to be destroyed. */
         if (parent_device)

dlls/dxgi/swapchain.c

@@ -168,9 +168,7 @@ static ULONG STDMETHODCALLTYPE d3d11_swapchain_Release(IDXGISwapChain1 *iface)
         }
         if (swapchain->factory)
             IDXGIFactory_Release(swapchain->factory);
-        wined3d_mutex_lock();
         wined3d_swapchain_decref(swapchain->wined3d_swapchain);
-        wined3d_mutex_unlock();
         if (device)
             IWineDXGIDevice_Release(device);
     }

dlls/wined3d/swapchain.c

@@ -109,17 +109,22 @@ ULONG CDECL wined3d_swapchain_incref(struct wined3d_swapchain *swapchain)
 ULONG CDECL wined3d_swapchain_decref(struct wined3d_swapchain *swapchain)
 {
     ULONG refcount = InterlockedDecrement(&swapchain->ref);
+    struct wined3d_device *device;
 
     TRACE("%p decreasing refcount to %u.\n", swapchain, refcount);
 
     if (!refcount)
     {
-        struct wined3d_device *device = swapchain->device;
+        wined3d_mutex_lock();
 
+        device = swapchain->device;
         device->cs->ops->finish(device->cs, WINED3D_CS_QUEUE_DEFAULT);
 
         swapchain_cleanup(swapchain);
         swapchain->parent_ops->wined3d_object_destroyed(swapchain->parent);
+
+        wined3d_mutex_unlock();
+
         heap_free(swapchain);
     }