From db80ff5477ed71286d2945b507adccf2030638b5 Mon Sep 17 00:00:00 2001
From: Gauvain 'GovanifY' Roussel-Tarbouriech <gauvain@govanify.com>
Date: Sat, 19 Jun 2021 09:46:34 +0200
Subject: [PATCH] mtgs: fix threading woes

---
 pcsx2/MTGS.cpp               | 10 +++++-----
 pcsx2/gui/GlobalCommands.cpp |  2 ++
 pcsx2/gui/SysState.cpp       |  2 ++
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/pcsx2/MTGS.cpp b/pcsx2/MTGS.cpp
index ece921aaa6..992c1fd5a7 100644
--- a/pcsx2/MTGS.cpp
+++ b/pcsx2/MTGS.cpp
@@ -595,14 +595,13 @@ void SysMtgsThread::CloseGS()
 	if (!m_Opened || GSDump::isRunning)
 		return;
 	m_Opened = false;
-	Suspend();
+	GSclose();
 	sApp.CloseGsPanel();
 }
 
 void SysMtgsThread::OnSuspendInThread()
 {
-	GSclose();
-	GetSysExecutorThread().PostEvent(new SysExecEvent_InvokeMtgsThreadMethod(&SysMtgsThread::CloseGS));
+	CloseGS();
 	_parent::OnSuspendInThread();
 }
 
@@ -616,7 +615,7 @@ void SysMtgsThread::OnResumeInThread(bool isSuspended)
 
 void SysMtgsThread::OnCleanupInThread()
 {
-	GetSysExecutorThread().PostEvent(new SysExecEvent_InvokeMtgsThreadMethod(&SysMtgsThread::CloseGS));
+	CloseGS();
 	_parent::OnCleanupInThread();
 }
 
@@ -925,8 +924,9 @@ void SysMtgsThread::WaitForOpen()
 
 void SysMtgsThread::Freeze(int mode, MTGS_FreezeData& data)
 {
-	Resume();
+	pxAssertDev(!IsSelf(), "This method is only allowed from threads *not* named MTGS.");
 	SendPointerPacket(GS_RINGTYPE_FREEZE, mode, &data);
+	// make sure MTGS is processing the packet we send it
 	Resume();
 	// we are forced to wait for the semaphore to be released, otherwise
 	// we'll end up in a state where the main thread is stuck on WaitGS
diff --git a/pcsx2/gui/GlobalCommands.cpp b/pcsx2/gui/GlobalCommands.cpp
index e23dbac952..fdff630a13 100644
--- a/pcsx2/gui/GlobalCommands.cpp
+++ b/pcsx2/gui/GlobalCommands.cpp
@@ -400,6 +400,7 @@ namespace Implementations
 			return;
 		if (renderswitch_delay == 0)
 		{
+			ScopedCoreThreadPause paused_core;
 			freezeData fP = {0, nullptr};
 			MTGS_FreezeData sstate = {&fP, 0};
 			GetMTGS().Freeze(FREEZE_SIZE, sstate);
@@ -410,6 +411,7 @@ namespace Implementations
 			GetMTGS().Freeze(FREEZE_LOAD, sstate);
 			delete[] fP.data;
 			renderswitch_delay = -1;
+			paused_core.AllowResume();
 		}
 	}
 
diff --git a/pcsx2/gui/SysState.cpp b/pcsx2/gui/SysState.cpp
index 6a86d0932f..debaebbf40 100644
--- a/pcsx2/gui/SysState.cpp
+++ b/pcsx2/gui/SysState.cpp
@@ -53,8 +53,10 @@ struct SysState_Component
 
 int SysState_MTGSFreeze(int mode, freezeData* fP)
 {
+	ScopedCoreThreadPause paused_core;
 	MTGS_FreezeData sstate = {fP, 0};
 	GetMTGS().Freeze(mode, sstate);
+	paused_core.AllowResume();
 	return sstate.retval;
 }