KiTryToAcquireThreadLock

char __fastcall KiTryToAcquireThreadLock(__int64 a1, _BYTE *a2){
  if( _interlockedbittestandset64((volatile signed __int32 *)(a1 + 64), 0i64) )
    return 0;
  if( a2 )
    *a2 = 1;
  return 1;
}

Referenced by:

KeTryToInsertQueueApc
KiDeferredReadySingleThread
KiMonitorCacheErrata
KiQueueReadyThread
KiTryToUpdateVPBackingThreadPriority
KiUpdateGlobalCpuSetConfiguration