Fix a specific core migration bug on the scheduler (#2271)

Ryujinx.HLE/HOS/Kernel/Threading/KScheduler.cs

@@ -22,8 +22,8 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
         private struct SchedulingState
         {
-            public bool NeedsScheduling;
-            public KThread SelectedThread;
+            public volatile bool NeedsScheduling;
+            public volatile KThread SelectedThread;
         }
 
         private SchedulingState _state;
@@ -349,31 +349,29 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
             nextThread ??= _idleThread;
 
-            if (currentThread == nextThread)
+            if (currentThread != nextThread)
             {
-                return;
-            }
+                long previousTicks = LastContextSwitchTime;
+                long currentTicks = PerformanceCounter.ElapsedTicks;
+                long ticksDelta = currentTicks - previousTicks;
 
-            long previousTicks = LastContextSwitchTime;
-            long currentTicks = PerformanceCounter.ElapsedTicks;
-            long ticksDelta = currentTicks - previousTicks;
+                currentThread.AddCpuTime(ticksDelta);
 
-            currentThread.AddCpuTime(ticksDelta);
-
-            if (currentProcess != null)
-            {
-                currentProcess.AddCpuTime(ticksDelta);
-            }
+                if (currentProcess != null)
+                {
+                    currentProcess.AddCpuTime(ticksDelta);
+                }
 
-            LastContextSwitchTime = currentTicks;
+                LastContextSwitchTime = currentTicks;
 
-            if (currentProcess != null)
-            {
-                _previousThread = !currentThread.TerminationRequested && currentThread.ActiveCore == _coreId ? currentThread : null;
-            }
-            else if (currentThread == _idleThread)
-            {
-                _previousThread = null;
+                if (currentProcess != null)
+                {
+                    _previousThread = !currentThread.TerminationRequested && currentThread.ActiveCore == _coreId ? currentThread : null;
+                }
+                else if (currentThread == _idleThread)
+                {
+                    _previousThread = null;
+                }
             }
 
             if (nextThread.CurrentCore != _coreId)
@@ -469,6 +467,11 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
         {
             KThread currentThread = KernelStatic.GetCurrentThread();
 
+            if (!currentThread.IsSchedulable)
+            {
+                return;
+            }
+
             context.CriticalSection.Enter();
 
             if (currentThread.SchedFlags != ThreadSchedState.Running)
@@ -491,6 +494,11 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
         {
             KThread currentThread = KernelStatic.GetCurrentThread();
 
+            if (!currentThread.IsSchedulable)
+            {
+                return;
+            }
+
             context.CriticalSection.Enter();
 
             if (currentThread.SchedFlags != ThreadSchedState.Running)
@@ -550,6 +558,11 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
         {
             KThread currentThread = KernelStatic.GetCurrentThread();
 
+            if (!currentThread.IsSchedulable)
+            {
+                return;
+            }
+
             context.CriticalSection.Enter();
 
             if (currentThread.SchedFlags != ThreadSchedState.Running)