Revert suspension related changes for now, as we need stable master.

It will be re-introduced later (revised).

The now-reverted changes were prompted by exposing GTA streaming race conditions, but since what exposed them was also reverted for stability reasons, it's not urgent.
Everything (and related) will be re-pushed when fully tested.

Author: Dutchman101

Client/game_sa/CModelInfoSA.cpp

@@ -488,15 +488,6 @@ bool CModelInfoSA::DoIsLoaded()
     return bLoaded;
 }
 
-bool CModelInfoSA::IsCollisionLoaded()
-{
-    m_pInterface = ppModelInfo[m_dwModelID];
-    if (!m_pInterface || !m_pInterface->pColModel)
-        return false;
-
-    return m_pInterface->pColModel->m_data != nullptr;
-}
-
 unsigned short CModelInfoSA::GetFlags()
 {
     return ppModelInfo[m_dwModelID]->usFlags;

Client/game_sa/CModelInfoSA.h

@@ -389,7 +389,6 @@ class CModelInfoSA : public CModelInfo
     void           Remove();
     bool           UnloadUnused();
     bool           IsLoaded();
-    bool           IsCollisionLoaded() override;
     bool           DoIsLoaded();
     unsigned short GetFlags();
     unsigned short GetOriginalFlags();

Client/game_sa/CVehicleSA.cpp

@@ -1360,8 +1360,11 @@ void CVehicleSA::SetHandlingData(CHandlingEntry* pHandling)
     // Store the handling and recalculate it
     m_pHandlingData = static_cast<CHandlingEntrySA*>(pHandling);
     pVehicleInterface->pHandlingData = m_pHandlingData->GetInterface();
-
-    RecalculateHandling();
+    
+    // Only recalculate if collision model is loaded (needed for suspension lines)
+    CModelInfo* pModelInfo = pGame->GetModelInfo(GetModelIndex());
+    if (pModelInfo && pModelInfo->GetInterface()->pColModel && pModelInfo->GetInterface()->pColModel->m_data)
+        RecalculateHandling();
 }
 
 void CVehicleSA::SetFlyingHandlingData(CFlyingHandlingEntry* pFlyingHandling)
@@ -1382,18 +1385,16 @@ void CVehicleSA::RecalculateHandling()
     if (!pInt)
         return;
 
+    // Ensure collision model is loaded before recalculating (needed for suspension lines)
     CModelInfo* pModelInfo = pGame->GetModelInfo(GetModelIndex());
-    auto* pModelInterface = pModelInfo ? pModelInfo->GetInterface() : nullptr;
-    auto* pColModelInterface = pModelInterface ? pModelInterface->pColModel : nullptr;
-    bool  bSuspensionDataReady = pColModelInterface && pColModelInterface->m_data;
-    bool  bHasSuspension = pModelInfo &&
-                      (pModelInfo->IsCar() || pModelInfo->IsMonsterTruck() || pModelInfo->IsTrailer() || pModelInfo->IsBike());
+    if (!pModelInfo || !pModelInfo->GetInterface()->pColModel || !pModelInfo->GetInterface()->pColModel->m_data)
+        return;
 
     m_pHandlingData->Recalculate();
 
     // Recalculate the suspension lines (only for vehicles that have suspension)
-    // Skip until collision data streams in to avoid accessing null suspension lines
-    if (bSuspensionDataReady && bHasSuspension)
+    // Already validated that pColModel and m_data exist above
+    if (pModelInfo->IsCar() || pModelInfo->IsMonsterTruck() || pModelInfo->IsTrailer() || pModelInfo->IsBike())
         RecalculateSuspensionLines();
 
     // Put it in our interface
@@ -1838,37 +1839,20 @@ void CVehicleSA::RecalculateSuspensionLines()
 
     DWORD       dwModel = GetModelIndex();
     CModelInfo* pModelInfo = pGame->GetModelInfo(dwModel);
-    if (pModelInfo && (pModelInfo->IsCar() || pModelInfo->IsMonsterTruck() || pModelInfo->IsTrailer()))
+    if (pModelInfo && pModelInfo->IsMonsterTruck() || pModelInfo->IsCar())
     {
         // Trains (Their trailers do as well!)
         if (pModelInfo->IsTrain() || dwModel == 571 || dwModel == 570 || dwModel == 569 || dwModel == 590)
             return;
 
         // Ensure collision model is loaded before setting up suspension
-        auto* pColModelInterface = pModelInfo->GetInterface()->pColModel;
-        if (!pColModelInterface || !pColModelInterface->m_data)
+        if (!pModelInfo->GetInterface()->pColModel || !pModelInfo->GetInterface()->pColModel->m_data)
             return;
 
-        struct ScopedModelRef
-        {
-            explicit ScopedModelRef(CModelInfo* model)
-                : m_Model(model)
-            {
-                if (m_Model)
-                    m_Model->ModelAddRef(EModelRequestType::BLOCKING, "CVehicleSA::RecalculateSuspensionLines");
-            }
-
-            ~ScopedModelRef()
-            {
-                if (m_Model)
-                    m_Model->RemoveRef();
-            }
-
-            CModelInfo* m_Model;
-        } modelRef(pModelInfo);
-
-        GetVehicleInterface()->SetupSuspensionLines();
-
+        // Note: We skip calling SetupSuspensionLines() because it's GTA SA's native code that can
+        // access pColModel->m_data without validation. If collision model is unloaded during execution
+        // (race condition), it causes crashes. CopyGlobalSuspensionLinesToPrivate() is safer as it
+        // validates collision model before accessing.
         CopyGlobalSuspensionLinesToPrivate();
     }
 }

Client/mods/deathmatch/logic/CClientVehicle.cpp

@@ -4300,15 +4300,6 @@ void CClientVehicle::ApplyHandling()
     if (!m_pVehicle)
         return;
 
-    // Ensure model is loaded before recalculating handling
-    CModelInfo* pModelInfo = g_pGame->GetModelInfo(GetModel());
-    if (!pModelInfo || !pModelInfo->IsLoaded())
-        return;
-
-    // Ensure collision model is loaded before recalculating (needed for suspension lines)
-    if (!pModelInfo->IsCollisionLoaded())
-        return;
-
     m_pVehicle->RecalculateHandling();
 
     if (m_eVehicleType == CLIENTVEHICLE_BMX || m_eVehicleType == CLIENTVEHICLE_BIKE)

Client/mods/deathmatch/logic/CStaticFunctionDefinitions.cpp

@@ -9015,10 +9015,6 @@ bool CStaticFunctionDefinitions::SetVehicleHandling(CClientVehicle* pVehicle, Ha
     {
         if (SetEntryHandling(pEntry, eProperty, ucValue))
         {
-            CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-            if (!pModelInfo || !pModelInfo->IsLoaded())
-                return false;
-
             pVehicle->ApplyHandling();
             return true;
         }
@@ -9036,10 +9032,6 @@ bool CStaticFunctionDefinitions::SetVehicleHandling(CClientVehicle* pVehicle, Ha
     {
         if (SetEntryHandling(pEntry, eProperty, uiValue))
         {
-            CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-            if (!pModelInfo || !pModelInfo->IsLoaded())
-                return false;
-
             pVehicle->ApplyHandling();
             return true;
         }
@@ -9057,10 +9049,6 @@ bool CStaticFunctionDefinitions::SetVehicleHandling(CClientVehicle* pVehicle, Ha
     {
         if (SetEntryHandling(pEntry, eProperty, fValue))
         {
-            CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-            if (!pModelInfo || !pModelInfo->IsLoaded())
-                return false;
-
             pVehicle->ApplyHandling();
             return true;
         }
@@ -9078,10 +9066,6 @@ bool CStaticFunctionDefinitions::SetVehicleHandling(CClientVehicle* pVehicle, Ha
     {
         if (SetEntryHandling(pEntry, eProperty, strValue))
         {
-            CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-            if (!pModelInfo || !pModelInfo->IsLoaded())
-                return false;
-
             pVehicle->ApplyHandling();
             return true;
         }
@@ -9099,10 +9083,6 @@ bool CStaticFunctionDefinitions::SetVehicleHandling(CClientVehicle* pVehicle, Ha
     {
         if (SetEntryHandling(pEntry, eProperty, vecValue))
         {
-            CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-            if (!pModelInfo || !pModelInfo->IsLoaded())
-                return false;
-
             pVehicle->ApplyHandling();
             return true;
         }
@@ -9161,10 +9141,6 @@ bool CStaticFunctionDefinitions::ResetVehicleHandling(CClientVehicle* pVehicle)
             pEntry->SetSuspensionUpperLimit(pEntry->GetSuspensionLowerLimit() - 0.1f);
     }
 
-    CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-    if (!pModelInfo || !pModelInfo->IsLoaded())
-        return false;
-
     pVehicle->ApplyHandling();
 
     return true;
@@ -9214,10 +9190,6 @@ bool CStaticFunctionDefinitions::ResetVehicleHandlingProperty(CClientVehicle* pV
             return false;
         }
 
-        CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-        if (!pModelInfo || !pModelInfo->IsLoaded())
-            return false;
-
         pVehicle->ApplyHandling();
 
         return true;

Client/mods/deathmatch/logic/luadefs/CLuaVehicleDefs.cpp

@@ -2518,15 +2518,6 @@ int CLuaVehicleDefs::SetVehicleHandling(lua_State* luaVM)
 
     if (!argStream.HasErrors())
     {
-        // Check if the vehicle model is loaded
-        CModelInfo* pModelInfo = g_pGame->GetModelInfo(pVehicle->GetModel());
-        if (!pModelInfo || !pModelInfo->IsLoaded())
-        {
-            m_pScriptDebugging->LogWarning(luaVM, "setVehicleHandling failed: vehicle model not loaded");
-            lua_pushboolean(luaVM, false);
-            return 1;
-        }
-
         if (argStream.NextIsString())
         {
             SString strProperty;

Client/sdk/game/CModelInfo.h

@@ -162,7 +162,6 @@ class CModelInfo
     virtual BYTE           GetVehicleType() const noexcept = 0;
     virtual void           Request(EModelRequestType requestType, const char* szTag /* = NULL*/) = 0;
     virtual bool           IsLoaded() = 0;
-    virtual bool           IsCollisionLoaded() = 0;
     virtual unsigned short GetFlags() = 0;
     virtual unsigned short GetOriginalFlags() = 0;
     virtual void           SetFlags(unsigned short usFlags) = 0;