[PATCH 0/1] MR10324: win32u: Fix deadlock when setting hdc_src to the window's self DC.

[Zhao Yi (＠Zhaoyi)]

Supersed !9180 and !9177

When hdc_src is the window's self DC, there is no need to call AlphaBlend. same as when hdc_src is NULL.

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10324

[PATCH 1/1] win32u: Fix deadlock when setting hdc_src to the window's self DC.

[Zhao Yi]

From: Zhao Yi <[e-mail]>

Signed-off-by: Zhao Yi <[e-mail]>
---
 dlls/win32u/window.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/win32u/window.c b/dlls/win32u/window.c
index fc129df0785..350c9092de8 100644
--- a/dlls/win32u/window.c
+++ b/dlls/win32u/window.c
@@ -2678,7 +2678,7 @@ BOOL WINAPI NtUserUpdateLayeredWindow( HWND hwnd, HDC hdc_dst, const POINT *pts_
     apply_window_pos( hwnd, 0, swp_flags, surface, &new_rects, NULL );
     if (!surface) return FALSE;
 
-    if (!hdc_src || surface == &dummy_surface)
+    if (!hdc_src || surface == &dummy_surface || (NtUserWindowFromDC( hdc_src ) == hwnd))
     {
         user_driver->pUpdateLayeredWindow( hwnd, source_alpha, flags );
         ret = TRUE;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10324

[Zhao Yi (＠Zhaoyi)]

There is a test program used to test the deadlock issue caused by setting **hdc_src** to the **window's self DC** when calling the **UpdateLayeredWindow** function.

demo: [test-UpdateLayeredWindow.exe](/uploads/96eeece57b90c76daf22c8293f4cb718/test-UpdateLayeredWindow.exe) [test-UpdateLayeredWindow.cpp](/uploads/ebdf27dc9a9fea676fc10b11c8e14a12/test-UpdateLayeredWindow.cpp)

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10324#note_132163

[Zhao Yi (＠Zhaoyi)]

Add some debug logs to the **UpdateLayeredWindow** function as follows:

![hdc1](/uploads/d8b526304cf9c5fd6a0ae36a620316c0/hdc1.png){width=900 height=148}

Then running test program test-UpdateLayeredWindow.exe, and deadlock,run result as follows:

![hdc2](/uploads/40a5892913b8b0d72590e59d4557356b/hdc2.png){width=900 height=183}

After applying my MR, run the test program again, and the window displays normally, run result as follows:

![hdc3](/uploads/085153accaac09d6c640a754cfdc284d/hdc3.png){width=900 height=372}

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10324#note_132165

[PATCH 0/1] MR10324: Draft: win32u: Fix deadlock when setting hdc_src to the window's self DC.

[Zhao Yi (＠Zhaoyi)]

Sorry, There are some incorrect behaviors here, and I need to continue analyzing them, so I'm marking this MR as a draft for now.

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10324#note_132342