From 972fc6a18ba9b7e76629d921b0d0d06b83998e7e Mon Sep 17 00:00:00 2001
From: Sour <mesenemu@gmail.com>
Date: Fri, 21 Jan 2022 19:49:51 -0500
Subject: [PATCH] Fixed deadlock when switching game while paused

---
 Core/Shared/Emulator.cpp | 12 +++++++-----
 Core/Shared/Emulator.h   |  1 -
 Utilities/SimpleLock.cpp |  7 ++++++-
 Utilities/SimpleLock.h   |  1 +
 4 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/Core/Shared/Emulator.cpp b/Core/Shared/Emulator.cpp
index 6ce67d06..ab5d66ce 100644
--- a/Core/Shared/Emulator.cpp
+++ b/Core/Shared/Emulator.cpp
@@ -102,8 +102,7 @@ void Emulator::Run()
 		return;
 	}
 
-	auto lock = _runLock.AcquireSafe();
-	auto emulationLock = _emulationLock.AcquireSafe();
+	_runLock.Acquire();
 
 	_stopFlag = false;
 	_isRunAheadFrame = false;
@@ -151,6 +150,11 @@ void Emulator::Run()
 
 	_emulationThreadId = thread::id();
 
+	if(_runLock.IsLockedByCurrentThread()) {
+		//Lock might not be held by current frame is _stopFlag was set to interrupt the thread
+		_runLock.Release();
+	}
+
 	PlatformUtilities::RestoreTimerResolution();
 }
 
@@ -288,8 +292,6 @@ void Emulator::Stop(bool sendNotification)
 		debugger->Run();
 	}
 
-	_emulationLock.WaitForRelease();
-
 	if(_emuThread) {
 		_emuThread->join();
 		_emuThread.release();
@@ -686,8 +688,8 @@ void Emulator::WaitForPauseEnd()
 	PlatformUtilities::DisableScreensaver();
 	PlatformUtilities::EnableHighResolutionTimer();
 
-	_runLock.Acquire();
 	if(!_stopFlag) {
+		_runLock.Acquire();
 		_notificationManager->SendNotification(ConsoleNotificationType::GameResumed);
 	}
 }
diff --git a/Core/Shared/Emulator.h b/Core/Shared/Emulator.h
index 63f2b2c7..746b0a1f 100644
--- a/Core/Shared/Emulator.h
+++ b/Core/Shared/Emulator.h
@@ -78,7 +78,6 @@ private:
 
 	atomic<uint32_t> _lockCounter;
 	SimpleLock _runLock;
-	SimpleLock _emulationLock;
 	SimpleLock _loadLock;
 
 	SimpleLock _debuggerLock;
diff --git a/Utilities/SimpleLock.cpp b/Utilities/SimpleLock.cpp
index b3f6946e..790a6058 100644
--- a/Utilities/SimpleLock.cpp
+++ b/Utilities/SimpleLock.cpp
@@ -37,6 +37,11 @@ bool SimpleLock::IsFree()
 	return _lockCount == 0;
 }
 
+bool SimpleLock::IsLockedByCurrentThread()
+{
+	return _lockCount > 0 && _holderThreadID == _threadID;
+}
+
 void SimpleLock::WaitForRelease()
 {
 	//Wait until we are able to grab a lock, and then release it again
@@ -46,7 +51,7 @@ void SimpleLock::WaitForRelease()
 
 void SimpleLock::Release()
 {
-	if(_lockCount > 0 && _holderThreadID == _threadID) {
+	if(IsLockedByCurrentThread()) {
 		_lockCount--;
 		if(_lockCount == 0) {
 			_holderThreadID = std::thread::id();
diff --git a/Utilities/SimpleLock.h b/Utilities/SimpleLock.h
index 630a3ab6..da7cb77f 100644
--- a/Utilities/SimpleLock.h
+++ b/Utilities/SimpleLock.h
@@ -30,6 +30,7 @@ public:
 
 	void Acquire();
 	bool IsFree();
+	bool IsLockedByCurrentThread();
 	void WaitForRelease();
 	void Release();
 };