From feb39db90c5e9d7c8db472d726195462a03f5902 Mon Sep 17 00:00:00 2001
From: aglab2 <aglab3@gmail.com>
Date: Thu, 7 Nov 2024 21:46:05 +0800
Subject: [PATCH] Core: Fixed race condition deadlock in Enhancements

---
 Source/Common/CriticalSection.h               | 39 ++++++++++++++++
 .../N64System/Enhancement/Enhancements.cpp    | 45 ++++++++++---------
 .../N64System/Enhancement/Enhancements.h      |  6 ++-
 3 files changed, 67 insertions(+), 23 deletions(-)

diff --git a/Source/Common/CriticalSection.h b/Source/Common/CriticalSection.h
index 0ca1fbbb4..3c2f1f63f 100644
--- a/Source/Common/CriticalSection.h
+++ b/Source/Common/CriticalSection.h
@@ -34,3 +34,42 @@ private:
     CGuard(const CGuard & copy);
     CGuard & operator=(const CGuard & rhs);
 };
+
+class CUniqueLock
+{
+public:
+    CUniqueLock(CriticalSection & sectionName) :
+        m_cs(sectionName), m_locked(true)
+    {
+        m_cs.enter();
+    }
+    ~CUniqueLock()
+    {
+        if (m_locked)
+            m_cs.leave();
+    }
+
+    inline void lock()
+    {
+        if (!m_locked)
+        {
+            m_cs.enter();
+            m_locked = true;
+        }
+    }
+
+    inline void unlock()
+    {
+        if (m_locked)
+        {
+            m_cs.leave();
+            m_locked = false;
+        }
+    }
+
+private:
+    CriticalSection & m_cs;
+    bool m_locked;
+    CUniqueLock(const CUniqueLock & copy);
+    CUniqueLock & operator=(const CUniqueLock & rhs);
+};
diff --git a/Source/Project64-core/N64System/Enhancement/Enhancements.cpp b/Source/Project64-core/N64System/Enhancement/Enhancements.cpp
index ad015b839..1e3f36723 100644
--- a/Source/Project64-core/N64System/Enhancement/Enhancements.cpp
+++ b/Source/Project64-core/N64System/Enhancement/Enhancements.cpp
@@ -32,7 +32,7 @@ CEnhancements::GAMESHARK_CODE::GAMESHARK_CODE(uint32_t Command, uint16_t Value,
 CEnhancements::CEnhancements() :
     m_ScanFileThread((CThread::CTHREAD_START_ROUTINE)stScanFileThread),
     m_Scan(true),
-    m_Scanned(false),
+    m_Scanned(true /*manual reset*/),
     m_UpdateCheats(false),
     m_OverClock(false),
     m_OverClockModifier(1)
@@ -48,11 +48,11 @@ CEnhancements::~CEnhancements()
 
 void CEnhancements::ApplyActive(CMipsMemoryVM & MMU, CPlugins * Plugins, bool UpdateChanges)
 {
-    CGuard Guard(m_CS);
+    CUniqueLock Guard(m_CS);
     if (m_UpdateCheats && UpdateChanges)
     {
         m_UpdateCheats = false;
-        LoadActive(&MMU, Plugins);
+        LoadActiveImpl(Guard, &MMU, Plugins);
     }
     for (size_t i = 0, n = m_ActiveCodes.size(); i < n; i++)
     {
@@ -263,20 +263,20 @@ void CEnhancements::LoadEnhancements(const char * Ident, SectionFiles & Files, s
     }
 }
 
-void CEnhancements::Load(void)
+void CEnhancements::LoadImpl(CUniqueLock & guard)
 {
+    guard.unlock();
     WaitScanDone();
-    CGuard Guard(m_CS);
+    guard.lock();
 
     LoadEnhancements(CEnhancement::CheatIdent, m_CheatFiles, m_CheatFile, m_Cheats);
     LoadEnhancements(CEnhancement::EnhancementIdent, m_EnhancementFiles, m_EnhancementFile, m_Enhancements);
 }
 
-void CEnhancements::LoadActive(CMipsMemoryVM * MMU, CPlugins * Plugins)
+void CEnhancements::LoadActiveImpl(CUniqueLock & guard, CMipsMemoryVM * MMU, CPlugins * Plugins)
 {
-    Load();
+    LoadImpl(guard);
 
-    CGuard Guard(m_CS);
     m_OverClock = false;
     m_OverClockModifier = 1;
 
@@ -703,25 +703,14 @@ void CEnhancements::ScanFileThread(void)
         CGuard Guard(m_CS);
         m_CheatFiles = CheatFiles;
         m_EnhancementFiles = EnhancementFiles;
-        m_Scanned = true;
     }
+
+    m_Scanned.Trigger();
 }
 
 void CEnhancements::WaitScanDone()
 {
-    for (uint32_t i = 0; i < 500; i++)
-    {
-        bool Scanned = false;
-        {
-            CGuard Guard(m_CS);
-            Scanned = m_Scanned;
-        }
-        if (Scanned)
-        {
-            break;
-        }
-        pjutil::Sleep(100);
-    }
+    m_Scanned.IsTriggered(50 * 1000 /*ms*/);
 }
 
 uint32_t CEnhancements::ConvertXP64Address(uint32_t Address)
@@ -739,3 +728,15 @@ uint16_t CEnhancements::ConvertXP64Value(uint16_t Value)
     tmpValue += ((Value + 0x002B) ^ 0x0085) & 0x00FF;
     return tmpValue;
 }
+
+void CEnhancements::Load(void)
+{
+    CUniqueLock Guard(m_CS);
+    return LoadImpl(Guard);
+}
+
+void CEnhancements::LoadActive(CMipsMemoryVM * MMU, CPlugins * Plugins)
+{
+    CUniqueLock Guard(m_CS);
+    return LoadActiveImpl(Guard, MMU, Plugins);
+}
diff --git a/Source/Project64-core/N64System/Enhancement/Enhancements.h b/Source/Project64-core/N64System/Enhancement/Enhancements.h
index f1e61f59f..b7a96f68e 100644
--- a/Source/Project64-core/N64System/Enhancement/Enhancements.h
+++ b/Source/Project64-core/N64System/Enhancement/Enhancements.h
@@ -1,5 +1,6 @@
 #pragma once
 #include <Common/CriticalSection.h>
+#include <Common/SyncEvent.h>
 #include <Common/Thread.h>
 #include <Project64-core/N64System/Enhancement/EnhancementFile.h>
 #include <Project64-core/N64System/Enhancement/EnhancementList.h>
@@ -33,6 +34,9 @@ public:
     CEnhancementList Enhancements(void);
 
 private:
+    void LoadImpl(CUniqueLock &);
+    void LoadActiveImpl(CUniqueLock &, CMipsMemoryVM * MMU, CPlugins * Plugins);
+
     class GAMESHARK_CODE
     {
     public:
@@ -115,7 +119,7 @@ private:
     ORIGINAL_VALUES8 m_OriginalValues8;
     CThread m_ScanFileThread;
     bool m_Scan;
-    bool m_Scanned;
+    SyncEvent m_Scanned;
     bool m_UpdateCheats;
     bool m_OverClock;
     uint32_t m_OverClockModifier;