[PATCH 2/4] ntoskrnl.exe: Implement KeAcquireSpinLockAtDpcLevel().

[Zebediah Figura]

Signed-off-by: Zebediah Figura <z.figura12 at gmail.com>
---
 dlls/ntoskrnl.exe/ntoskrnl.exe.spec |  2 +-
 dlls/ntoskrnl.exe/sync.c            | 10 ++++++++++
 include/ddk/wdm.h                   |  1 +
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
index e861000f26..33aa108cd7 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
+++ b/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
diff --git a/dlls/ntoskrnl.exe/sync.c b/dlls/ntoskrnl.exe/sync.c
index b439695fd7..31a3ad7209 100644
--- a/dlls/ntoskrnl.exe/sync.c
+++ b/dlls/ntoskrnl.exe/sync.c
@@ -395,6 +395,16 @@ static inline void small_pause(void)
 #endif
 }
 
+/***********************************************************************
+ *           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.@)
  */
diff --git a/include/ddk/wdm.h b/include/ddk/wdm.h
index 908e71c72d..81f41f5a97 100644
--- a/include/ddk/wdm.h
+++ b/include/ddk/wdm.h
@@ -1454,6 +1454,7 @@ 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*);
-- 
2.20.1