[PATCH 6/6] ntoskrnl.exe: Implement KeAcquireSpinLockRaiseToDpc().

[Zebediah Figura]

Signed-off-by: Zebediah Figura 
---
 dlls/ntoskrnl.exe/ntoskrnl.c        |  9 ---------
 dlls/ntoskrnl.exe/ntoskrnl.exe.spec |  2 +-
 dlls/ntoskrnl.exe/sync.c            | 20 ++++++++++++++++++++
 include/ddk/wdm.h                   |  3 +++
 4 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/dlls/ntoskrnl.exe/ntoskrnl.c b/dlls/ntoskrnl.exe/ntoskrnl.c
index 26668408a6..e6bb5930bd 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.c
+++ b/dlls/ntoskrnl.exe/ntoskrnl.c
@@ -3859,15 +3859,6 @@ void WINAPI KeReleaseInStackQueuedSpinLock( KLOCK_QUEUE_HANDLE *handle )
     FIXME( "stub: %p\n", handle );
 }

-/***********************************************************************
- *           KeAcquireSpinLockRaiseToDpc (NTOSKRNL.EXE.@)
- */
-KIRQL WINAPI KeAcquireSpinLockRaiseToDpc(KSPIN_LOCK *spinlock)
-{
-    FIXME( "stub: %p\n", spinlock );
-    return 0;
-}
-
 /***********************************************************************
  *           IoCreateNotificationEvent (NTOSKRNL.EXE.@)
  */
diff --git a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
index c4a4213287..3de7c1cac7 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
+++ b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
@@ -511,7 +511,7 @@
 @ stdcall Ke386SetIoAccessMap(long ptr)
 @ stub KeAcquireInterruptSpinLock
 @ stub KeAcquireSpinLockAtDpcLevel
-@ stdcall -arch=x86_64 KeAcquireSpinLockRaiseToDpc(ptr)
+@ stdcall -arch=arm,arm64,x86_64 KeAcquireSpinLockRaiseToDpc(ptr)
 @ stub KeAddSystemServiceTable
 @ stub KeAreApcsDisabled
 @ stub KeAttachProcess
diff --git a/dlls/ntoskrnl.exe/sync.c b/dlls/ntoskrnl.exe/sync.c
index 832b0480b9..74e84a6505 100644
--- a/dlls/ntoskrnl.exe/sync.c
+++ b/dlls/ntoskrnl.exe/sync.c
@@ -384,6 +384,15 @@ void WINAPI KeInitializeSpinLock( KSPIN_LOCK *lock )
 }

#ifndef __i386__
+static inline void small_pause(void)
+{
+#ifdef __x86_64__
+    __asm__ __volatile__( "rep;nop" : : : "memory" );
+#else
+    __asm__ __volatile__( "" : : : "memory" );
+#endif
+}
+
 /***********************************************************************
  *           KeReleaseSpinLock (NTOSKRNL.EXE.@)
  */
@@ -392,4 +401,15 @@ void WINAPI KeReleaseSpinLock( KSPIN_LOCK *lock, KIRQL irql )
     TRACE("lock %p, irql %u.\n", lock, irql);
     InterlockedExchangePointer( (void **)lock, 0 );
 }
+
+/***********************************************************************
+ *           KeAcquireSpinLockRaiseToDpc (NTOSKRNL.EXE.@)
+ */
+KIRQL WINAPI KeAcquireSpinLockRaiseToDpc( KSPIN_LOCK *lock )
+{
+    TRACE("lock %p.\n", lock);
+    while (!InterlockedCompareExchangePointer( (void **)lock, (void *)1, (void *)0 ))
+        small_pause();
+    return 0;
+}
 #endif
diff --git a/include/ddk/wdm.h b/include/ddk/wdm.h
index 6b62811a67..258fdb3893 100644
--- a/include/ddk/wdm.h
+++ b/include/ddk/wdm.h
@@ -1448,6 +1448,9 @@ NTSTATUS  WINAPI IoWMIRegistrationControl(PDEVICE_OBJECT,ULONG);

#ifdef __i386__
 void      WINAPI KeAcquireSpinLock(KSPIN_LOCK*,KIRQL*);
+#else
+#define KeAcquireSpinLock( lock, irql ) *(irql) = KeAcquireSpinLockRaiseToDpc( lock )
+KIRQL     WINAPI KeAcquireSpinLockRaiseToDpc(KSPIN_LOCK*);
 #endif
 BOOLEAN   WINAPI KeCancelTimer(KTIMER*);
 void      WINAPI KeClearEvent(PRKEVENT);