From 1daa56c61b00f166bd1dc235b5782c6a68de0a37 Mon Sep 17 00:00:00 2001
From: Koundinya Veluri <kouvel@microsoft.com>
Date: Thu, 16 Nov 2023 12:15:06 -0800
Subject: [PATCH] Fix Lock's usage of NativeRuntimeEventSource.Log to account
 for recursive accesses during its own class construction

- `NativeRuntimeEventSource.Log` can be null if it's being constructed in the same thread earlier in the stack, added null checks

Fixes https://github.com/dotnet/runtime/issues/94728
---
 .../src/System/Threading/Lock.NativeAot.cs                | 2 +-
 .../System.Private.CoreLib/src/System/Threading/Lock.cs   | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Lock.NativeAot.cs b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Lock.NativeAot.cs
index 492e186b95bfc..318a8cc768024 100644
--- a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Lock.NativeAot.cs
+++ b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Lock.NativeAot.cs
@@ -173,7 +173,7 @@ private static bool TryInitializeStatics()
                 s_minSpinCount = DetermineMinSpinCount();
 
                 // Also initialize some types that are used later to prevent potential class construction cycles
-                NativeRuntimeEventSource.Log.IsEnabled();
+                _ = NativeRuntimeEventSource.Log;
             }
             catch
             {
diff --git a/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs b/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs
index fe794fdf9426e..056ff96d41b1e 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Threading/Lock.cs
@@ -444,9 +444,9 @@ private ThreadId TryEnterSlow(int timeoutMs, ThreadId currentThreadId)
 
         Wait:
             bool areContentionEventsEnabled =
-                NativeRuntimeEventSource.Log.IsEnabled(
+                NativeRuntimeEventSource.Log?.IsEnabled(
                     EventLevel.Informational,
-                    NativeRuntimeEventSource.Keywords.ContentionKeyword);
+                    NativeRuntimeEventSource.Keywords.ContentionKeyword) ?? false;
             AutoResetEvent waitEvent = _waitEvent ?? CreateWaitEvent(areContentionEventsEnabled);
             if (State.TryLockBeforeWait(this))
             {
@@ -463,7 +463,7 @@ private ThreadId TryEnterSlow(int timeoutMs, ThreadId currentThreadId)
                 long waitStartTimeTicks = 0;
                 if (areContentionEventsEnabled)
                 {
-                    NativeRuntimeEventSource.Log.ContentionStart(this);
+                    NativeRuntimeEventSource.Log!.ContentionStart(this);
                     waitStartTimeTicks = Stopwatch.GetTimestamp();
                 }
 
@@ -535,7 +535,7 @@ private ThreadId TryEnterSlow(int timeoutMs, ThreadId currentThreadId)
                     {
                         double waitDurationNs =
                             (Stopwatch.GetTimestamp() - waitStartTimeTicks) * 1_000_000_000.0 / Stopwatch.Frequency;
-                        NativeRuntimeEventSource.Log.ContentionStop(waitDurationNs);
+                        NativeRuntimeEventSource.Log!.ContentionStop(waitDurationNs);
                     }
 
                     return currentThreadId;