ntoskrnl.exe: Implement KeAcquireSpinLockAtDpcLevel().

dlls/ntoskrnl.exe/ntoskrnl.exe.spec

@@ -510,7 +510,7 @@
 @ stub Ke386QueryIoAccessMap
 @ stdcall Ke386SetIoAccessMap(long ptr)
 @ stub KeAcquireInterruptSpinLock
-@ stub KeAcquireSpinLockAtDpcLevel
+@ stdcall KeAcquireSpinLockAtDpcLevel(ptr)
 @ stdcall -arch=arm,arm64,x86_64 KeAcquireSpinLockRaiseToDpc(ptr)
 @ stub KeAddSystemServiceTable
 @ stub KeAreApcsDisabled

dlls/ntoskrnl.exe/sync.c

@@ -396,6 +396,16 @@ static inline void small_pause(void)
 }
 
 /***********************************************************************
+ *           KeAcquireSpinLockAtDpcLevel (NTOSKRNL.EXE.@)
+ */
+void WINAPI KeAcquireSpinLockAtDpcLevel( KSPIN_LOCK *lock )
+{
+    TRACE("lock %p.\n", lock);
+    while (!InterlockedCompareExchangePointer( (void **)lock, (void *)1, (void *)0 ))
+        small_pause();
+}
+
+/***********************************************************************
  *           KeReleaseSpinLockFromDpcLevel (NTOSKRNL.EXE.@)
  */
 void WINAPI KeReleaseSpinLockFromDpcLevel( KSPIN_LOCK *lock )

include/ddk/wdm.h

@@ -1427,6 +1427,7 @@ void      WINAPI KeAcquireSpinLock(KSPIN_LOCK*,KIRQL*);
 #define KeAcquireSpinLock( lock, irql ) *(irql) = KeAcquireSpinLockRaiseToDpc( lock )
 KIRQL     WINAPI KeAcquireSpinLockRaiseToDpc(KSPIN_LOCK*);
 #endif
+void      WINAPI KeAcquireSpinLockAtDpcLevel(KSPIN_LOCK*);
 BOOLEAN   WINAPI KeCancelTimer(KTIMER*);
 void      WINAPI KeClearEvent(PRKEVENT);
 NTSTATUS  WINAPI KeDelayExecutionThread(KPROCESSOR_MODE,BOOLEAN,LARGE_INTEGER*);