System.Threading.RegisteredWaitHandleSafe.Unregister C# (CSharp) Method

        internal bool Unregister(
             WaitHandle     waitObject          // object to be notified when all callbacks to delegates have completed
             )
        {
            bool result = false;
            // needed for DangerousRelease
            RuntimeHelpers.PrepareConstrainedRegions();
            try
            {
            }
            finally
            {
                // lock(this) cannot be used reliably in Cer since thin lock could be
                // promoted to syncblock and that is not a guaranteed operation
                bool bLockTaken = false;
                do 
                {
                    if (Interlocked.CompareExchange(ref m_lock, 1, 0) == 0)
                    {
                        bLockTaken = true;
                        try
                        {
                            if (ValidHandle())
                            {
                                result = UnregisterWaitNative(GetHandle(), waitObject == null ? null : waitObject.SafeWaitHandle);
                                if (result == true)
                                {
                                    if (bReleaseNeeded)
                                    {
                                        m_internalWaitObject.SafeWaitHandle.DangerousRelease();
                                        bReleaseNeeded = false;
                                    }
                                    // if result not true don't release/suppress here so finalizer can make another attempt
                                    SetHandle(InvalidHandle);
                                    m_internalWaitObject = null;
                                    GC.SuppressFinalize(this);
                                }
                            }
                        }
                        finally
                        {
                            m_lock = 0;
                        }
                    }
                    Thread.SpinWait(1);     // yield to processor
                }
                while (!bLockTaken);
            }
            return result;
        }

 public bool Unregister(
     WaitHandle?waitObject            // object to be notified when all callbacks to delegates have completed
     )
 {
     return(internalRegisteredWait.Unregister(waitObject));
 }