Re: [PATCH 0/1] MR9180: win32u: Fix deadlock caused by nested locking.

[Zhao Yi (＠Zhaoyi)]

On Fri Oct 17 08:35:05 2025 +0000, Zhao Yi wrote:
> Just wrote a test program as follows: 
> Test1:
> HDC hdc = GetDC(hWndA); 
> BOOL ret = UpdateLayeredWindow(hWndA, NULL, NULL, &si, hdc, &pi, 0, &bf,
> ULW_ALPHA); 
> ReleaseDC(hWndA, hdc);
>
> Test2:
> HDC hdc = CreateCompatibleDC(NULL); 
> BOOL ret = UpdateLayeredWindow(hWndA, NULL, NULL, &si, hdc, &pi, 0, &bf,
> ULW_ALPHA); 
> ReleaseDC(NULL, hdc);
>
> The test results confirm what you said: 
> The window DC created in Test1 doesn't unnecessary to lock the surface,
> and calling window_surface_lock would cause a deadlock.
>
> The compatible DC created in Test2 requires locking.

After applying the changes according to the patch file, the call to the UpdateLayeredWindow function failed. I will continue to analyze the cause.
[fix-deadlock.patch](/uploads/51708682a6c0d42328d07e5a05bb6468/fix-deadlock.patch)