mirror of
https://github.com/reactos/reactos.git
synced 2024-12-28 10:04:49 +00:00
hopefully a better implementation of rundown protections, thanks also to Alex.
svn path=/trunk/; revision=11395
This commit is contained in:
Thomas Bluemel
parent
1270089c9f
commit
75009fd35f
2 changed files with 129 additions and 49 deletions
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@ -1,4 +1,4 @@
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/* $Id: extypes.h,v 1.24 2004/10/03 03:03:53 ion Exp $ */
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/* $Id: extypes.h,v 1.25 2004/10/22 22:49:00 weiden Exp $ */
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#ifndef __INCLUDE_DDK_EXTYPES_H
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#define __INCLUDE_DDK_EXTYPES_H
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@ -39,16 +39,18 @@ typedef struct _ERESOURCE
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} ERESOURCE, *PERESOURCE;
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#define EX_RUNDOWN_ACTIVE 0x1
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#define EX_RUNDOWN_COUNT_SHIFT 0x1
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#define EX_RUNDOWN_COUNT_INC (0x1 << EX_RUNDOWN_COUNT_SHIFT)
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typedef struct _RUNDOWN_DESCRIPTOR {
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ULONG References;
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PKEVENT RundownEvent;
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ULONG_PTR References;
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KEVENT RundownEvent;
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} RUNDOWN_DESCRIPTOR, *PRUNDOWN_DESCRIPTOR;
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typedef struct _EX_RUNDOWN_REF {
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union {
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ULONG_PTR Count;
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PRUNDOWN_DESCRIPTOR Pointer;
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PRUNDOWN_DESCRIPTOR Ptr;
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};
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} EX_RUNDOWN_REF, *PEX_RUNDOWN_REF;
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@ -1,6 +1,6 @@
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/*
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* ReactOS kernel
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* Copyright (C) 1998, 1999, 2000, 2001 ReactOS Team
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* Copyright (C) 1998 - 2004 ReactOS Team
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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@ -54,11 +54,27 @@ ExAcquireRundownProtectionEx (
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IN ULONG Count
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)
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{
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/* Make sure a Rundown is not in progress */
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if (RunRef->Count & EX_RUNDOWN_ACTIVE) return FALSE;
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ULONG_PTR PrevCount, Current;
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Count <<= EX_RUNDOWN_COUNT_SHIFT;
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/* Loop until successfully incremented the counter */
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do
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{
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Current = RunRef->Count;
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/* Make sure a rundown is not active */
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if (Current & EX_RUNDOWN_ACTIVE)
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{
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return FALSE;
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}
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/* Increment Reference Count */
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RunRef->Count += Count * 2;
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#ifdef _WIN64
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PrevCount = (ULONG_PTR)InterlockedExchangeAdd64((LONGLONG*)&RunRef->Count, (LONGLONG)Count);
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#else
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PrevCount = (ULONG_PTR)InterlockedExchangeAdd((LONG*)&RunRef->Count, (LONG)Count);
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#endif
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} while (PrevCount != Current);
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/* Return Success */
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return TRUE;
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@ -87,7 +103,11 @@ ExReInitializeRundownProtection (
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)
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{
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/* Reset the count */
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RunRef->Count = 0;
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#ifdef _WIN64
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InterlockedExchangeAdd64((LONGLONG*)&RunRef->Count, 0LL);
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#else
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InterlockedExchangeAdd((LONG*)&RunRef->Count, 0);
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#endif
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}
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@ -101,26 +121,67 @@ ExReleaseRundownProtectionEx (
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IN ULONG Count
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)
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{
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PRUNDOWN_DESCRIPTOR RundownDescriptor;
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Count <<= EX_RUNDOWN_COUNT_SHIFT;
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for (;;)
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{
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ULONG_PTR Current = RunRef->Count;
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/* Check if Rundown is active */
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if (Current & EX_RUNDOWN_ACTIVE)
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{
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/* Get Pointer */
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PRUNDOWN_DESCRIPTOR RundownDescriptor = (PRUNDOWN_DESCRIPTOR)((ULONG_PTR)RunRef->Ptr & ~EX_RUNDOWN_ACTIVE);
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/* Check if Rundown is in progress */
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if (RunRef->Count & EX_RUNDOWN_ACTIVE) {
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/* Decrease Reference Count by RundownDescriptor->References */
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for (;;)
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{
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ULONG_PTR PrevCount, NewCount;
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/* Get Pointer */
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RundownDescriptor = RunRef->Pointer;
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if ((Current >> EX_RUNDOWN_COUNT_SHIFT) == RundownDescriptor->References)
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{
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NewCount = 0;
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}
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else
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{
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NewCount = (((Current >> EX_RUNDOWN_COUNT_SHIFT) - RundownDescriptor->References) << EX_RUNDOWN_COUNT_SHIFT) | EX_RUNDOWN_ACTIVE;
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}
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#ifdef _WIN64
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PrevCount = (ULONG_PTR)InterlockedCompareExchange64((LONGLONG*)&RunRef->Count, (LONGLONG)NewCount, (LONGLONG)Current);
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#else
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PrevCount = (ULONG_PTR)InterlockedCompareExchange((LONG*)&RunRef->Count, (LONG)NewCount, (LONG)Current);
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#endif
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if (PrevCount == Current)
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{
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if (NewCount == 0)
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{
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/* Signal the event so anyone waiting on it can now kill it */
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KeSetEvent(&RundownDescriptor->RundownEvent, 0, FALSE);
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}
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/* Decrease Reference Count */
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RundownDescriptor->References -= Count;
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/* If anyone else is still referencing, don't signal the event */
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if (RundownDescriptor->References) return;
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/* Signal the event so anyone waiting on it can now kill it */
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KeSetEvent(RundownDescriptor->RundownEvent, 0, FALSE);
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} else {
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/* Decrease Count */
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RunRef->Count -= Count * 2;
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/* Successfully decremented the counter, so bail! */
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break;
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}
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Current = PrevCount;
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}
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break;
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}
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else
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{
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ULONG_PTR PrevCount, NewCount = Current - (ULONG_PTR)Count;
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#ifdef _WIN64
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PrevCount = (ULONG_PTR)InterlockedCompareExchange64((LONGLONG*)&RunRef->Count, (LONGLONG)NewCount, (LONGLONG)Current);
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#else
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PrevCount = (ULONG_PTR)InterlockedCompareExchange((LONG*)&RunRef->Count, (LONG)NewCount, (LONG)Current);
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#endif
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if (PrevCount == Current)
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{
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/* Successfully decremented the counter, so bail! */
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break;
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}
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}
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}
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}
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@ -134,7 +195,7 @@ ExReleaseRundownProtection (
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)
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{
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/* Call the general function with only 1 reference removal */
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ExReleaseRundownProtectionEx(RunRef, 1);
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ExReleaseRundownProtectionEx(RunRef, 1);
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}
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/*
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@ -146,8 +207,12 @@ ExRundownCompleted (
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IN PEX_RUNDOWN_REF RunRef
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)
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{
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/* Remove pending rundown */
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RunRef->Count++;
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/* mark the */
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#ifdef _WIN64
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InterlockedExchange64((LONGLONG*)&RunRef->Count, (LONGLONG)EX_RUNDOWN_ACTIVE);
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#else
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InterlockedExchange((LONG*)&RunRef->Count, EX_RUNDOWN_ACTIVE);
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#endif
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}
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/*
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@ -159,30 +224,43 @@ ExWaitForRundownProtectionRelease (
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IN PEX_RUNDOWN_REF RunRef
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)
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{
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ULONG_PTR PrevCount, NewPtr, PrevPtr;
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RUNDOWN_DESCRIPTOR RundownDescriptor;
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#ifdef _WIN64
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PrevCount = (ULONG_PTR)InterlockedCompareExchange64((LONGLONG*)&RunRef->Ptr, (LONGLONG)EX_RUNDOWN_ACTIVE, 0LL);
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#else
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PrevCount = (ULONG_PTR)InterlockedCompareExchange((LONG*)&RunRef->Ptr, EX_RUNDOWN_ACTIVE, 0);
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#endif
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/* Check if anyone is referencing the structure */
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if (!RunRef->Count) {
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/* It's free, set it to Rundown Mode */
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RunRef->Count = EX_RUNDOWN_ACTIVE;
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} else {
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/* Check if it's already in rundown */
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if (RunRef->Count == EX_RUNDOWN_ACTIVE) return;
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if (PrevCount == 0 ||
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PrevCount & EX_RUNDOWN_ACTIVE)
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{
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return;
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}
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/* Save number of references */
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RundownDescriptor.References = RunRef->Count / 2;
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/* save the reference counter */
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RundownDescriptor.References = PrevCount >> EX_RUNDOWN_COUNT_SHIFT;
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/* Pending references... wait on them to be closed with an event */
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KeInitializeEvent(RundownDescriptor.RundownEvent, NotificationEvent, FALSE);
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/* Save Rundown Descriptor. This is safe because this stack won't be modified */
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RunRef->Pointer = &RundownDescriptor;
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/* Set the Count to 1 so nobody else acquires and so release notifies us */
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RunRef->Count++;
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KeInitializeEvent(&RundownDescriptor.RundownEvent, NotificationEvent, FALSE);
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NewPtr = (ULONG_PTR)&RundownDescriptor | EX_RUNDOWN_ACTIVE;
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PrevCount = EX_RUNDOWN_ACTIVE;
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do
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{
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#ifdef _WIN64
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PrevPtr = (ULONG_PTR)InterlockedCompareExchange64((LONGLONG*)&RunRef->Ptr, (LONGLONG)NewPtr, (LONGLONG)PrevCount);
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#else
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PrevPtr = (ULONG_PTR)InterlockedCompareExchange((LONG*)&RunRef->Ptr, (LONG)NewPtr, (LONG)PrevCount);
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#endif
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PrevCount = PrevPtr;
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} while (PrevPtr != PrevCount);
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/* Wait for whoever needs to release to notify us */
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KeWaitForSingleObject(RundownDescriptor.RundownEvent, Executive, KernelMode, FALSE, NULL);
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KeWaitForSingleObject(&RundownDescriptor.RundownEvent, Executive, KernelMode, FALSE, NULL);
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}
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/* EOF */
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