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reactos/ntoskrnl/ex/rundown.c

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/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS Kernel
* FILE: ntoskrnl/ex/rundown.c
* PURPOSE: Rundown and Cache-Aware Rundown Protection
* PROGRAMMERS: Alex Ionescu (alex@relsoft.net)
* Thomas Weidenmueller
*/
/* INCLUDES *****************************************************************/
#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>
/* FUNCTIONS *****************************************************************/
/*++
* @name ExfAcquireRundownProtection
* @implemented NT5.1
*
* The ExfAcquireRundownProtection routine acquires rundown protection for
* the specified descriptor.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @return TRUE if access to the protected structure was granted, FALSE otherwise.
*
* @remarks Callers of ExfAcquireRundownProtection can be running at any IRQL.
*
*--*/
BOOLEAN
FASTCALL
ExfAcquireRundownProtection(IN PEX_RUNDOWN_REF RunRef)
{
ULONG_PTR Value = RunRef->Count, NewValue;
/* Loop until successfully incremented the counter */
for (;;)
{
/* Make sure a rundown is not active */
if (Value & EX_RUNDOWN_ACTIVE) return FALSE;
/* Add a reference */
NewValue = Value + EX_RUNDOWN_COUNT_INC;
/* Change the value */
NewValue = ExpChangeRundown(RunRef, NewValue, Value);
if (NewValue == Value) return TRUE;
/* Update it */
Value = NewValue;
}
}
/*++
* @name ExfAcquireRundownProtectionEx
* @implemented NT5.2
*
* The ExfAcquireRundownProtectionEx routine acquires multiple rundown
* protection references for the specified descriptor.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @param Count
* Number of times to reference the descriptor.
*
* @return TRUE if access to the protected structure was granted, FALSE otherwise.
*
* @remarks Callers of ExfAcquireRundownProtectionEx can be running at any IRQL.
*
*--*/
BOOLEAN
FASTCALL
ExfAcquireRundownProtectionEx(IN PEX_RUNDOWN_REF RunRef,
IN ULONG Count)
{
ULONG_PTR Value = RunRef->Count, NewValue;
/* Loop until successfully incremented the counter */
for (;;)
{
/* Make sure a rundown is not active */
if (Value & EX_RUNDOWN_ACTIVE) return FALSE;
/* Add references */
NewValue = Value + EX_RUNDOWN_COUNT_INC * Count;
/* Change the value */
NewValue = ExpChangeRundown(RunRef, NewValue, Value);
if (NewValue == Value) return TRUE;
/* Update the value */
Value = NewValue;
}
}
/*++
* @name ExfInitializeRundownProtection
* @implemented NT5.1
*
* The ExfInitializeRundownProtection routine initializes a rundown
* protection descriptor.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @return None.
*
* @remarks Callers of ExfInitializeRundownProtection can be running at any IRQL.
*
*--*/
VOID
FASTCALL
ExfInitializeRundownProtection(IN PEX_RUNDOWN_REF RunRef)
{
/* Set the count to zero */
RunRef->Count = 0;
}
/*++
* @name ExfReInitializeRundownProtection
* @implemented NT5.1
*
* The ExfReInitializeRundownProtection routine re-initializes a rundown
* protection descriptor.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @return None.
*
* @remarks Callers of ExfReInitializeRundownProtection can be running at any IRQL.
*
*--*/
VOID
FASTCALL
ExfReInitializeRundownProtection(IN PEX_RUNDOWN_REF RunRef)
{
PAGED_CODE();
/* Sanity check */
ASSERT((RunRef->Count & EX_RUNDOWN_ACTIVE) != 0);
/* Reset the count */
ExpSetRundown(RunRef, 0);
}
/*++
* @name ExfRundownCompleted
* @implemented NT5.1
*
* The ExfRundownCompleted routine completes the rundown of the specified
* descriptor by setting the active bit.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @return None.
*
* @remarks Callers of ExfRundownCompleted must be running at IRQL <= APC_LEVEL.
*
*--*/
VOID
FASTCALL
ExfRundownCompleted(IN PEX_RUNDOWN_REF RunRef)
{
PAGED_CODE();
/* Sanity check */
ASSERT((RunRef->Count & EX_RUNDOWN_ACTIVE) != 0);
/* Mark the counter as active */
ExpSetRundown(RunRef, EX_RUNDOWN_ACTIVE);
}
/*++
* @name ExfReleaseRundownProtection
* @implemented NT5.1
*
* The ExfReleaseRundownProtection routine releases the rundown protection
* reference for the specified descriptor.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @return None.
*
* @remarks Callers of ExfReleaseRundownProtection can be running at any IRQL.
*
*--*/
VOID
FASTCALL
ExfReleaseRundownProtection(IN PEX_RUNDOWN_REF RunRef)
{
ULONG_PTR Value = RunRef->Count, NewValue;
PEX_RUNDOWN_WAIT_BLOCK WaitBlock;
/* Loop until successfully incremented the counter */
for (;;)
{
/* Check if rundown is not active */
if (!(Value & EX_RUNDOWN_ACTIVE))
{
/* Sanity check */
ASSERT((Value >= EX_RUNDOWN_COUNT_INC) || (KeNumberProcessors > 1));
/* Get the new value */
NewValue = Value - EX_RUNDOWN_COUNT_INC;
/* Change the value */
NewValue = ExpChangeRundown(RunRef, NewValue, Value);
if (NewValue == Value) break;
/* Update value */
Value = NewValue;
}
else
{
/* Get the wait block */
WaitBlock = (PEX_RUNDOWN_WAIT_BLOCK)(Value & ~EX_RUNDOWN_ACTIVE);
ASSERT((WaitBlock->Count > 0) || (KeNumberProcessors > 1));
/* Remove the one count */
if (!InterlockedDecrementSizeT(&WaitBlock->Count))
{
/* We're down to 0 now, so signal the event */
KeSetEvent(&WaitBlock->WakeEvent, IO_NO_INCREMENT, FALSE);
}
/* We're all done */
break;
}
}
}
/*++
* @name ExfReleaseRundownProtectionEx
* @implemented NT5.2
*
* The ExfReleaseRundownProtectionEx routine releases multiple rundown
* protection references for the specified descriptor.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @param Count
* Number of times to dereference the descriptor.
*
* @return None.
*
* @remarks Callers of ExfAcquireRundownProtectionEx can be running at any IRQL.
*
*--*/
VOID
FASTCALL
ExfReleaseRundownProtectionEx(IN PEX_RUNDOWN_REF RunRef,
IN ULONG Count)
{
ULONG_PTR Value = RunRef->Count, NewValue;
PEX_RUNDOWN_WAIT_BLOCK WaitBlock;
/* Loop until successfully incremented the counter */
for (;;)
{
/* Check if rundown is not active */
if (!(Value & EX_RUNDOWN_ACTIVE))
{
/* Sanity check */
ASSERT((Value >= EX_RUNDOWN_COUNT_INC * Count) ||
(KeNumberProcessors > 1));
/* Get the new value */
NewValue = Value - EX_RUNDOWN_COUNT_INC * Count;
/* Change the value */
NewValue = ExpChangeRundown(RunRef, NewValue, Value);
if (NewValue == Value) break;
/* Update value */
Value = NewValue;
}
else
{
/* Get the wait block */
WaitBlock = (PEX_RUNDOWN_WAIT_BLOCK)(Value & ~EX_RUNDOWN_ACTIVE);
ASSERT((WaitBlock->Count >= Count) || (KeNumberProcessors > 1));
/* Remove the counts */
if (InterlockedExchangeAddSizeT(&WaitBlock->Count,
-(LONG)Count) == (LONG)Count)
{
/* We're down to 0 now, so signal the event */
KeSetEvent(&WaitBlock->WakeEvent, IO_NO_INCREMENT, FALSE);
}
/* We're all done */
break;
}
}
}
/*++
* @name ExfWaitForRundownProtectionRelease
* @implemented NT5.1
*
* The ExfWaitForRundownProtectionRelease routine waits until the specified
* rundown descriptor has been released.
*
* @param RunRef
* Pointer to a rundown reference descriptor.
*
* @return None.
*
* @remarks Callers of ExfWaitForRundownProtectionRelease must be running
* at IRQL <= APC_LEVEL.
*
*--*/
VOID
FASTCALL
ExfWaitForRundownProtectionRelease(IN PEX_RUNDOWN_REF RunRef)
{
ULONG_PTR Value, Count, NewValue;
EX_RUNDOWN_WAIT_BLOCK WaitBlock;
PEX_RUNDOWN_WAIT_BLOCK WaitBlockPointer;
PKEVENT Event;
PAGED_CODE();
/* Set the active bit */
Value = ExpChangeRundown(RunRef, EX_RUNDOWN_ACTIVE, 0);
if ((Value == 0) || (Value == EX_RUNDOWN_ACTIVE)) return;
/* No event for now */
Event = NULL;
WaitBlockPointer = (PEX_RUNDOWN_WAIT_BLOCK)((ULONG_PTR)&WaitBlock |
EX_RUNDOWN_ACTIVE);
/* Start waitblock set loop */
for (;;)
{
/* Save the count */
Count = Value >> EX_RUNDOWN_COUNT_SHIFT;
/* If the count is over one and we don't have en event yet, create it */
if ((Count) && !(Event))
{
/* Initialize the event */
KeInitializeEvent(&WaitBlock.WakeEvent,
SynchronizationEvent,
FALSE);
/* Set the pointer */
Event = &WaitBlock.WakeEvent;
}
/* Set the count */
WaitBlock.Count = Count;
/* Now set the pointer */
NewValue = ExpChangeRundown(RunRef, (ULONG_PTR)WaitBlockPointer, Value);
if (NewValue == Value) break;
/* Loop again */
Value = NewValue;
ASSERT((Value & EX_RUNDOWN_ACTIVE) == 0);
}
/* If the count was 0, we're done */
if (!Count) return;
/* Wait for whoever needs to release to notify us */
KeWaitForSingleObject(Event, Executive, KernelMode, FALSE, NULL);
ASSERT(WaitBlock.Count == 0);
}
/* FIXME: STUBS **************************************************************/
/*
* @unimplemented NT5.2
*/
BOOLEAN
FASTCALL
ExfAcquireRundownProtectionCacheAware(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
UNIMPLEMENTED;
return FALSE;
}
/*
* @unimplemented NT5.2
*/
BOOLEAN
FASTCALL
ExfAcquireRundownProtectionCacheAwareEx(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware,
IN ULONG Count)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
DBG_UNREFERENCED_PARAMETER(Count);
UNIMPLEMENTED;
return FALSE;
}
/*
* @unimplemented NT5.2
*/
VOID
FASTCALL
ExfReleaseRundownProtectionCacheAware(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
UNIMPLEMENTED;
}
/*
* @unimplemented NT5.2
*/
VOID
FASTCALL
ExfReleaseRundownProtectionCacheAwareEx(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware,
IN ULONG Count)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
DBG_UNREFERENCED_PARAMETER(Count);
UNIMPLEMENTED;
}
/*
* @unimplemented NT5.2
*/
VOID
FASTCALL
ExfWaitForRundownProtectionReleaseCacheAware(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
UNIMPLEMENTED;
}
/*
* @unimplemented NT5.2
*/
VOID
FASTCALL
ExfRundownCompletedCacheAware(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
UNIMPLEMENTED;
}
/*
* @unimplemented NT5.2
*/
VOID
FASTCALL
ExfReInitializeRundownProtectionCacheAware(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
UNIMPLEMENTED;
}
/*
* @unimplemented NT5.2
*/
PEX_RUNDOWN_REF_CACHE_AWARE
NTAPI
ExAllocateCacheAwareRundownProtection(IN POOL_TYPE PoolType,
IN ULONG Tag)
{
DBG_UNREFERENCED_PARAMETER(PoolType);
DBG_UNREFERENCED_PARAMETER(Tag);
UNIMPLEMENTED;
return NULL;
}
/*
* @unimplemented NT5.2
*/
VOID
NTAPI
ExFreeCacheAwareRundownProtection(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
UNIMPLEMENTED;
}
/*
* @unimplemented NT5.2
*/
VOID
NTAPI
ExInitializeRundownProtectionCacheAware(IN PEX_RUNDOWN_REF_CACHE_AWARE RunRefCacheAware,
IN SIZE_T Count)
{
DBG_UNREFERENCED_PARAMETER(RunRefCacheAware);
DBG_UNREFERENCED_PARAMETER(Count);
UNIMPLEMENTED;
}
/*
* @unimplemented NT5.2
*/
SIZE_T
NTAPI
ExSizeOfRundownProtectionCacheAware(VOID)
{
UNIMPLEMENTED;
return 0;
}
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