From 5a18461fb84087b2d9b062733f7f833a5ab4cbd6 Mon Sep 17 00:00:00 2001
From: wangshaohui <97082645@qq.com>
Date: Wed, 1 Jan 2025 09:07:27 +0800
Subject: [PATCH] UI: Fix wrong order for requesting mutex

Below callstack is from graphic thread where gs_enter has been gotten.
As this, the order of requesting mutex is as gs->sources_mutex. That
is conflicting with basic logic in libobs. About basic request order,
sources_mutex should be requested before gs.

[callstask]
render_displays
(1)request gs enter
DrawSpacingHelpers()
CreateLabel
obs_source_create_private
(2)request obs->data.sources_mutex
---
 UI/window-basic-preview.cpp | 17 ++++++++++++++---
 UI/window-basic-preview.hpp |  1 +
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/UI/window-basic-preview.cpp b/UI/window-basic-preview.cpp
index 361e318c2f360c..c5ee42966c0a0c 100644
--- a/UI/window-basic-preview.cpp
+++ b/UI/window-basic-preview.cpp
@@ -2488,9 +2488,20 @@ void OBSBasicPreview::DrawSpacingHelpers()
 	vec3 start, end;
 
 	float pixelRatio = main->GetDevicePixelRatio();
-	for (int i = 0; i < 4; i++) {
-		if (!spacerLabel[i])
-			spacerLabel[i] = CreateLabel(pixelRatio, i);
+	if (!labelCreated) {
+		QMetaObject::invokeMethod(this, [this, pixelRatio]() {
+			if (labelCreated)
+				return;
+
+			for (int i = 0; i < 4; i++) {
+				if (!spacerLabel[i])
+					spacerLabel[i] = CreateLabel(pixelRatio, i);
+			}
+
+			labelCreated = true;
+		});
+
+		return; // wait label source to be created
 	}
 
 	vec3_set(&start, top.x, 0.0f, 1.0f);
diff --git a/UI/window-basic-preview.hpp b/UI/window-basic-preview.hpp
index e880a8dac9713a..6121cf755f64a7 100644
--- a/UI/window-basic-preview.hpp
+++ b/UI/window-basic-preview.hpp
@@ -188,6 +188,7 @@ private slots:
 	static inline void operator delete(void *ptr) { bfree(ptr); }
 
 	OBSSourceAutoRelease spacerLabel[4];
+	bool labelCreated = false;
 	int spacerPx[4] = {0};
 
 	void DrawSpacingHelpers();