[PATCH 0/1] MR8694: win32u: Clear DC opengl drawable when releasing cached dce.

[Rémi Bernon (＠rbernon)]

We won't be able to do it later on otherwise as get_dc_ptr will fail
with a disabled DC, and release_dce will then not clear the drawable.

This will delay the drawable release until the dce is later reused, for
instance for a different window, which may cause a complicated deadlock.

[PATCH 1/1] win32u: Clear DC opengl drawable when releasing cached dce.

[Rémi Bernon]

From: Rémi Bernon

We won't be able to do it later on otherwise as get_dc_ptr will fail
with a disabled DC, and release_dce will then not clear the drawable.

This will delay the drawable release until the dce is later reused, for
instance for a different window, which may cause a complicated deadlock.
---
 dlls/win32u/dce.c            | 1 +
 dlls/win32u/win32u_private.h | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/dlls/win32u/dce.c b/dlls/win32u/dce.c
index 29f11e18256..d1cf5c78bab 100644
--- a/dlls/win32u/dce.c
+++ b/dlls/win32u/dce.c
@@ -1224,6 +1224,7 @@ static INT release_dc( HWND hwnd, HDC hdc, BOOL end_paint )
         if (end_paint || (dce->flags & DCX_CACHE)) delete_clip_rgn( dce );
         if (dce->flags & DCX_CACHE)
         {
+            set_dc_opengl_drawable( dce->hdc, NULL );
             dce->count = 0;
             set_dce_flags( dce->hdc, DCHF_DISABLEDC );
         }
diff --git a/dlls/win32u/win32u_private.h b/dlls/win32u/win32u_private.h
index 780e8cd26cc..e683f7cd824 100644
--- a/dlls/win32u/win32u_private.h
+++ b/dlls/win32u/win32u_private.h
@@ -193,7 +193,7 @@ extern void user_check_not_lock(void);
 /* opengl.c */

struct opengl_drawable;
-void set_dc_opengl_drawable( HDC hdc, struct opengl_drawable *new_drawable );
+extern void set_dc_opengl_drawable( HDC hdc, struct opengl_drawable *new_drawable );

/* d3dkmtc. */

[Rémi Bernon (＠rbernon)]

@huw I'm not sure this is the best way to fix this. Another option is to use `get_dc_obj` instead of `get_dc_ptr` to access the DC object in `get_dc_opengl_drawable`/`set_dc_opengl_drawable`, but the function is static and I felt that exporting it would make things more confusing. I could also move the `dc_opengl` functions to dc.c, though I would prefer to keep GL stuff together.

Note that I'm also a bit lost in the DC/dce logic, their lifetime, and how they get reused. Using them to hold the GL surfaces was a convenient way to replace the drivers DC/surface tracking but it's maybe not the best way.