Re: [PATCH 1/3] wined3d: Handle discarded buffers in buffer_resource_sub_resource_map().

[Henri Verbeet]

On Tue, 25 Jan 2022 at 03:21, Zebediah Figura  wrote:
> @@ -927,10 +928,13 @@ static HRESULT buffer_resource_sub_resource_map(struct wined3d_resource *resourc
>  count = ++resource->map_count;
>
> - if (buffer->buffer_object)
> - context = context_acquire(device, NULL, 0);
> -
> - wined3d_buffer_get_memory(buffer, context, &addr);
> -
> - if (addr.buffer_object)
> {

I think that potentially changes the location we map in some cases.
(In particular, when buffer->buffer_object is non-NULL, but
WINED3D_LOCATION_BUFFER is not current.) I don't know for sure whether
that would cause issues for applications, but this code is sensitive
enough that I'd prefer avoiding wined3d_buffer_get_memory() here
unless we have a good reason not to.

What is the issue exactly? Is it that buffer->buffer_object may not
have been created yet for discarded resources?