VOID
MiSetDirtyBit (
IN PVOID FaultingAddress,
IN PMMPTE PointerPte,
IN ULONG PfnHeld
)
/*++
Routine Description:
This routine sets dirty in the specified PTE and the modify bit in the
correpsonding PFN element. If any page file space is allocated, it
is deallocated.
Arguments:
FaultingAddress - Supplies the faulting address.
PointerPte - Supplies a pointer to the corresponding valid PTE.
PfnHeld - Supplies TRUE if the PFN mutex is already held.
Return Value:
None.
Environment:
Kernel mode, APC's disabled, Working set mutex held.
--*/
{
MMPTE TempPte;
ULONG PageFrameIndex;
PMMPFN Pfn1;
KIRQL OldIrql;
//
// The page is NOT copy on write, update the PTE setting both the
// dirty bit and the accessed bit. Note, that as this PTE is in
// the TB, the TB must be flushed.
//
MmSetDirtyCount += 1; //fixfix - remove
TempPte = *PointerPte;
MI_SET_PTE_DIRTY (TempPte);
MI_SET_ACCESSED_IN_PTE (&TempPte, 1);
*PointerPte = TempPte;
//
// Check state of PFN mutex and if not held, don't update PFN database.
//
if (PfnHeld) {
PageFrameIndex = PointerPte->u.Hard.PageFrameNumber;
Pfn1 = MI_PFN_ELEMENT (PageFrameIndex);
//
// Set the modified field in the PFN database, also, if the phyiscal
// page is currently in a paging file, free up the page file space
// as the contents are now worthless.
//
if ((Pfn1->OriginalPte.u.Soft.Prototype == 0) &&
(Pfn1->u3.e1.WriteInProgress == 0)) {
//
// This page is in page file format, deallocate the page file space.
//
MiReleasePageFileSpace (Pfn1->OriginalPte);
//
// Change original PTE to indicate no page file space is reserved,
// otherwise the space will be deallocated when the PTE is
// deleted.
//
Pfn1->OriginalPte.u.Soft.PageFileHigh = 0;
}
Pfn1->u3.e1.Modified = 1;
}
//
// The TB entry must be flushed as the valid PTE with the dirty bit clear
// has been fetched into the TB. If it isn't flushed, another fault
// is generated as the dirty bit is not set in the cached TB entry.
//
KeFillEntryTb ((PHARDWARE_PTE)PointerPte, FaultingAddress, TRUE);
return;
}
LOGICAL
MiSetDirtyBit (
IN PVOID FaultingAddress,
IN PMMPTE PointerPte,
IN ULONG PfnHeld
)
/*++
Routine Description:
This routine sets dirty in the specified PTE and the modify bit in the
corresponding PFN element. If any page file space is allocated, it
is deallocated.
Arguments:
FaultingAddress - Supplies the faulting address.
PointerPte - Supplies a pointer to the corresponding valid PTE.
PfnHeld - Supplies TRUE if the PFN lock is already held.
Return Value:
TRUE if action was taken, FALSE if not.
Environment:
Kernel mode, APCs disabled, working set pushlock held.
--*/
{
MMPTE TempPte;
PFN_NUMBER PageFrameIndex;
PMMPFN Pfn1;
//
// The page is NOT copy on write, update the PTE setting both the
// dirty bit and the accessed bit. Note, that as this PTE is in
// the TB, the TB must be flushed.
//
TempPte = *PointerPte;
PageFrameIndex = MI_GET_PAGE_FRAME_FROM_PTE (&TempPte);
//
// This may be a PTE from a rotate physical frame so there may be no
// corresponding PFN for it.
//
if (!MI_IS_PFN (PageFrameIndex)) {
return FALSE;
}
MI_SET_PTE_DIRTY (TempPte);
MI_SET_ACCESSED_IN_PTE (&TempPte, 1);
MI_WRITE_VALID_PTE_NEW_PROTECTION (PointerPte, TempPte);
//
// Check state of PFN lock and if not held, don't update PFN database.
//
if (PfnHeld) {
Pfn1 = MI_PFN_ELEMENT (PageFrameIndex);
//
// Set the modified field in the PFN database, also, if the physical
// page is currently in a paging file, free up the page file space
// as the contents are now worthless.
//
if ((Pfn1->OriginalPte.u.Soft.Prototype == 0) &&
(Pfn1->u3.e1.WriteInProgress == 0)) {
//
// This page is in page file format, deallocate the page file space.
//
MiReleasePageFileSpace (Pfn1->OriginalPte);
//
// Change original PTE to indicate no page file space is reserved,
// otherwise the space will be deallocated when the PTE is
// deleted.
//
Pfn1->OriginalPte.u.Soft.PageFileHigh = 0;
}
MI_SET_MODIFIED (Pfn1, 1, 0x17);
}
//
// The TB entry must be flushed as the valid PTE with the dirty bit clear
// has been fetched into the TB. If it isn't flushed, another fault
// is generated as the dirty bit is not set in the cached TB entry.
//
KeFillEntryTb (FaultingAddress);
return TRUE;
}
BOOLEAN
MmCreateProcessAddressSpace (
IN ULONG MinimumWorkingSetSize,
IN PEPROCESS NewProcess,
OUT PULONG_PTR DirectoryTableBase
)
/*++
Routine Description:
This routine creates an address space which maps the system
portion and contains a hyper space entry.
Arguments:
MinimumWorkingSetSize - Supplies the minimum working set size for
this address space. This value is only used
to ensure that ample physical pages exist
to create this process.
NewProcess - Supplies a pointer to the process object being created.
DirectoryTableBase - Returns the value of the newly created
address space's Page Directory (PD) page and
hyper space page.
Return Value:
Returns TRUE if an address space was successfully created, FALSE
if ample physical pages do not exist.
Environment:
Kernel mode. APCs Disabled.
--*/
{
LOGICAL FlushTbNeeded;
PFN_NUMBER PageDirectoryIndex;
PFN_NUMBER HyperSpaceIndex;
PFN_NUMBER PageContainingWorkingSet;
PFN_NUMBER VadBitMapPage;
MMPTE TempPte;
MMPTE TempPte2;
PEPROCESS CurrentProcess;
KIRQL OldIrql;
PMMPFN Pfn1;
ULONG Color;
PMMPTE PointerPte;
ULONG PdeOffset;
PMMPTE MappingPte;
PMMPTE PointerFillPte;
PMMPTE CurrentAddressSpacePde;
//
// Charge commitment for the page directory pages, working set page table
// page, and working set list. If Vad bitmap lookups are enabled, then
// charge for a page or two for that as well.
//
if (MiChargeCommitment (MM_PROCESS_COMMIT_CHARGE, NULL) == FALSE) {
return FALSE;
}
FlushTbNeeded = FALSE;
CurrentProcess = PsGetCurrentProcess ();
NewProcess->NextPageColor = (USHORT) (RtlRandom (&MmProcessColorSeed));
KeInitializeSpinLock (&NewProcess->HyperSpaceLock);
//
// Get the PFN lock to get physical pages.
//
LOCK_PFN (OldIrql);
//
// Check to make sure the physical pages are available.
//
if (MI_NONPAGEABLE_MEMORY_AVAILABLE() <= (SPFN_NUMBER)MinimumWorkingSetSize){
UNLOCK_PFN (OldIrql);
MiReturnCommitment (MM_PROCESS_COMMIT_CHARGE);
//
// Indicate no directory base was allocated.
//
return FALSE;
}
MM_TRACK_COMMIT (MM_DBG_COMMIT_PROCESS_CREATE, MM_PROCESS_COMMIT_CHARGE);
MI_DECREMENT_RESIDENT_AVAILABLE (MinimumWorkingSetSize,
MM_RESAVAIL_ALLOCATE_CREATE_PROCESS);
//
// Allocate a page directory page.
//
if (MmAvailablePages < MM_HIGH_LIMIT) {
MiEnsureAvailablePageOrWait (NULL, OldIrql);
}
Color = MI_PAGE_COLOR_PTE_PROCESS (PDE_BASE,
&CurrentProcess->NextPageColor);
PageDirectoryIndex = MiRemoveZeroPageMayReleaseLocks (Color, OldIrql);
Pfn1 = MI_PFN_ELEMENT (PageDirectoryIndex);
if (Pfn1->u3.e1.CacheAttribute != MiCached) {
Pfn1->u3.e1.CacheAttribute = MiCached;
FlushTbNeeded = TRUE;
}
//
// Allocate the hyper space page table page.
//
if (MmAvailablePages < MM_HIGH_LIMIT) {
MiEnsureAvailablePageOrWait (NULL, OldIrql);
}
Color = MI_PAGE_COLOR_PTE_PROCESS (MiGetPdeAddress(HYPER_SPACE),
&CurrentProcess->NextPageColor);
HyperSpaceIndex = MiRemoveZeroPageMayReleaseLocks (Color, OldIrql);
Pfn1 = MI_PFN_ELEMENT (HyperSpaceIndex);
if (Pfn1->u3.e1.CacheAttribute != MiCached) {
Pfn1->u3.e1.CacheAttribute = MiCached;
FlushTbNeeded = TRUE;
}
//
// Remove page(s) for the VAD bitmap.
//
if (MmAvailablePages < MM_HIGH_LIMIT) {
MiEnsureAvailablePageOrWait (NULL, OldIrql);
}
Color = MI_PAGE_COLOR_VA_PROCESS (MmWorkingSetList,
&CurrentProcess->NextPageColor);
VadBitMapPage = MiRemoveZeroPageMayReleaseLocks (Color, OldIrql);
Pfn1 = MI_PFN_ELEMENT (VadBitMapPage);
if (Pfn1->u3.e1.CacheAttribute != MiCached) {
Pfn1->u3.e1.CacheAttribute = MiCached;
FlushTbNeeded = TRUE;
}
//
// Remove a page for the working set list.
//
if (MmAvailablePages < MM_HIGH_LIMIT) {
MiEnsureAvailablePageOrWait (NULL, OldIrql);
}
Color = MI_PAGE_COLOR_VA_PROCESS (MmWorkingSetList,
&CurrentProcess->NextPageColor);
PageContainingWorkingSet = MiRemoveZeroPageMayReleaseLocks (Color, OldIrql);
Pfn1 = MI_PFN_ELEMENT (PageContainingWorkingSet);
if (Pfn1->u3.e1.CacheAttribute != MiCached) {
Pfn1->u3.e1.CacheAttribute = MiCached;
FlushTbNeeded = TRUE;
}
UNLOCK_PFN (OldIrql);
if (FlushTbNeeded == TRUE) {
MI_FLUSH_TB_FOR_CACHED_ATTRIBUTE ();
}
ASSERT (NewProcess->AddressSpaceInitialized == 0);
PS_SET_BITS (&NewProcess->Flags, PS_PROCESS_FLAGS_ADDRESS_SPACE1);
ASSERT (NewProcess->AddressSpaceInitialized == 1);
NewProcess->Vm.MinimumWorkingSetSize = MinimumWorkingSetSize;
NewProcess->WorkingSetPage = PageContainingWorkingSet;
INITIALIZE_DIRECTORY_TABLE_BASE (&DirectoryTableBase[0], PageDirectoryIndex);
INITIALIZE_DIRECTORY_TABLE_BASE (&DirectoryTableBase[1], HyperSpaceIndex);
//
// Initialize the page reserved for hyper space.
//
TempPte = ValidPdePde;
MI_SET_GLOBAL_STATE (TempPte, 0);
MappingPte = MiReserveSystemPtes (1, SystemPteSpace);
if (MappingPte != NULL) {
MI_MAKE_VALID_KERNEL_PTE (TempPte2,
HyperSpaceIndex,
MM_READWRITE,
MappingPte);
MI_SET_PTE_DIRTY (TempPte2);
MI_WRITE_VALID_PTE (MappingPte, TempPte2);
PointerPte = MiGetVirtualAddressMappedByPte (MappingPte);
}
else {
PointerPte = MiMapPageInHyperSpace (CurrentProcess, HyperSpaceIndex, &OldIrql);
}
TempPte.u.Hard.PageFrameNumber = VadBitMapPage;
PointerPte[MiGetPteOffset(VAD_BITMAP_SPACE)] = TempPte;
TempPte.u.Hard.PageFrameNumber = PageContainingWorkingSet;
PointerPte[MiGetPteOffset(MmWorkingSetList)] = TempPte;
if (MappingPte != NULL) {
MiReleaseSystemPtes (MappingPte, 1, SystemPteSpace);
}
else {
MiUnmapPageInHyperSpace (CurrentProcess, PointerPte, OldIrql);
}
//
// Set the PTE address in the PFN for the page directory page.
//
Pfn1 = MI_PFN_ELEMENT (PageDirectoryIndex);
Pfn1->PteAddress = (PMMPTE)PDE_BASE;
TempPte = ValidPdePde;
TempPte.u.Hard.PageFrameNumber = HyperSpaceIndex;
MI_SET_GLOBAL_STATE (TempPte, 0);
//
// Add the new process to our internal list prior to filling any
// system PDEs so if a system PDE changes (large page map or unmap)
// it can mark this process for a subsequent update.
//
ASSERT (NewProcess->Pcb.DirectoryTableBase[0] == 0);
LOCK_EXPANSION (OldIrql);
InsertTailList (&MmProcessList, &NewProcess->MmProcessLinks);
UNLOCK_EXPANSION (OldIrql);
//
// Map the page directory page in hyperspace.
//
MappingPte = MiReserveSystemPtes (1, SystemPteSpace);
if (MappingPte != NULL) {
MI_MAKE_VALID_KERNEL_PTE (TempPte2,
PageDirectoryIndex,
MM_READWRITE,
MappingPte);
MI_SET_PTE_DIRTY (TempPte2);
MI_WRITE_VALID_PTE (MappingPte, TempPte2);
PointerPte = MiGetVirtualAddressMappedByPte (MappingPte);
}
else {
PointerPte = MiMapPageInHyperSpace (CurrentProcess, PageDirectoryIndex, &OldIrql);
}
PdeOffset = MiGetPdeOffset (MmSystemRangeStart);
PointerFillPte = &PointerPte[PdeOffset];
CurrentAddressSpacePde = MiGetPdeAddress (MmSystemRangeStart);
RtlCopyMemory (PointerFillPte,
CurrentAddressSpacePde,
PAGE_SIZE - PdeOffset * sizeof (MMPTE));
//
// Map the working set page table page.
//
PdeOffset = MiGetPdeOffset (HYPER_SPACE);
PointerPte[PdeOffset] = TempPte;
//
// Zero the remaining page directory range used to map the working
// set list and its hash.
//
PdeOffset += 1;
ASSERT (MiGetPdeOffset (MmHyperSpaceEnd) >= PdeOffset);
MiZeroMemoryPte (&PointerPte[PdeOffset],
(MiGetPdeOffset (MmHyperSpaceEnd) - PdeOffset + 1));
//
// Recursively map the page directory page so it points to itself.
//
TempPte.u.Hard.PageFrameNumber = PageDirectoryIndex;
PointerPte[MiGetPdeOffset(PTE_BASE)] = TempPte;
if (MappingPte != NULL) {
MiReleaseSystemPtes (MappingPte, 1, SystemPteSpace);
}
else {
MiUnmapPageInHyperSpace (CurrentProcess, PointerPte, OldIrql);
}
InterlockedExchangeAddSizeT (&MmProcessCommit, MM_PROCESS_COMMIT_CHARGE);
//
// Up the session space reference count.
//
MiSessionAddProcess (NewProcess);
return TRUE;
}
LOGICAL
FASTCALL
MiCopyOnWrite (
IN PVOID FaultingAddress,
IN PMMPTE PointerPte
)
/*++
Routine Description:
This routine performs a copy on write operation for the specified
virtual address.
Arguments:
FaultingAddress - Supplies the virtual address which caused the fault.
PointerPte - Supplies the pointer to the PTE which caused the page fault.
Return Value:
Returns TRUE if the page was actually split, FALSE if not.
Environment:
Kernel mode, APCs disabled, working set mutex held.
--*/
{
MMPTE TempPte;
MMPTE TempPte2;
PMMPTE MappingPte;
PFN_NUMBER PageFrameIndex;
PFN_NUMBER NewPageIndex;
PVOID CopyTo;
PVOID CopyFrom;
KIRQL OldIrql;
PMMPFN Pfn1;
PEPROCESS CurrentProcess;
PMMCLONE_BLOCK CloneBlock;
PMMCLONE_DESCRIPTOR CloneDescriptor;
WSLE_NUMBER WorkingSetIndex;
LOGICAL FakeCopyOnWrite;
PMMWSL WorkingSetList;
PVOID SessionSpace;
PLIST_ENTRY NextEntry;
PIMAGE_ENTRY_IN_SESSION Image;
//
// This is called from MmAccessFault, the PointerPte is valid
// and the working set mutex ensures it cannot change state.
//
// Capture the PTE contents to TempPte.
//
TempPte = *PointerPte;
ASSERT (TempPte.u.Hard.Valid == 1);
PageFrameIndex = MI_GET_PAGE_FRAME_FROM_PTE (&TempPte);
Pfn1 = MI_PFN_ELEMENT (PageFrameIndex);
//
// Check to see if this is a prototype PTE with copy on write enabled.
//
FakeCopyOnWrite = FALSE;
CurrentProcess = PsGetCurrentProcess ();
CloneBlock = NULL;
if (FaultingAddress >= (PVOID) MmSessionBase) {
WorkingSetList = MmSessionSpace->Vm.VmWorkingSetList;
ASSERT (Pfn1->u3.e1.PrototypePte == 1);
SessionSpace = (PVOID) MmSessionSpace;
MM_SESSION_SPACE_WS_LOCK_ASSERT ();
if (MmSessionSpace->ImageLoadingCount != 0) {
NextEntry = MmSessionSpace->ImageList.Flink;
while (NextEntry != &MmSessionSpace->ImageList) {
Image = CONTAINING_RECORD (NextEntry, IMAGE_ENTRY_IN_SESSION, Link);
if ((FaultingAddress >= Image->Address) &&
(FaultingAddress <= Image->LastAddress)) {
if (Image->ImageLoading) {
ASSERT (Pfn1->u3.e1.PrototypePte == 1);
TempPte.u.Hard.CopyOnWrite = 0;
TempPte.u.Hard.Write = 1;
//
// The page is no longer copy on write, update the PTE
// setting both the dirty bit and the accessed bit.
//
// Even though the page's current backing is the image
// file, the modified writer will convert it to
// pagefile backing when it notices the change later.
//
MI_SET_PTE_DIRTY (TempPte);
MI_SET_ACCESSED_IN_PTE (&TempPte, 1);
MI_WRITE_VALID_PTE_NEW_PROTECTION (PointerPte, TempPte);
//
// The TB entry must be flushed as the valid PTE with
// the dirty bit clear has been fetched into the TB. If
// it isn't flushed, another fault is generated as the
// dirty bit is not set in the cached TB entry.
//
MI_FLUSH_SINGLE_TB (FaultingAddress, TRUE);
return FALSE;
}
break;
}
NextEntry = NextEntry->Flink;
}
}
}
else {
WorkingSetList = MmWorkingSetList;
SessionSpace = NULL;
//
// If a fork operation is in progress, block until the fork is
// completed, then retry the whole operation as the state of
// everything may have changed between when the mutexes were
// released and reacquired.
//
if (CurrentProcess->ForkInProgress != NULL) {
if (MiWaitForForkToComplete (CurrentProcess) == TRUE) {
return FALSE;
}
}
if (TempPte.u.Hard.CopyOnWrite == 0) {
//
// This is a fork page which is being made private in order
// to change the protection of the page.
// Do not make the page writable.
//
FakeCopyOnWrite = TRUE;
}
}
WorkingSetIndex = MiLocateWsle (FaultingAddress,
WorkingSetList,
Pfn1->u1.WsIndex,
FALSE);
//
// The page must be copied into a new page.
//
LOCK_PFN (OldIrql);
if ((MmAvailablePages < MM_HIGH_LIMIT) &&
(MiEnsureAvailablePageOrWait (SessionSpace != NULL ? HYDRA_PROCESS : CurrentProcess, OldIrql))) {
//
// A wait operation was performed to obtain an available
// page and the working set mutex and PFN lock have
// been released and various things may have changed for
// the worse. Rather than examine all the conditions again,
// return and if things are still proper, the fault will
// be taken again.
//
UNLOCK_PFN (OldIrql);
return FALSE;
}
//
// This must be a prototype PTE. Perform the copy on write.
//
ASSERT (Pfn1->u3.e1.PrototypePte == 1);
//
// A page is being copied and made private, the global state of
// the shared page needs to be updated at this point on certain
// hardware. This is done by ORing the dirty bit into the modify bit in
// the PFN element.
//
// Note that a session page cannot be dirty (no POSIX-style forking is
// supported for these drivers).
//
if (SessionSpace != NULL) {
ASSERT ((TempPte.u.Hard.Valid == 1) && (TempPte.u.Hard.Write == 0));
ASSERT (!MI_IS_PTE_DIRTY (TempPte));
NewPageIndex = MiRemoveAnyPage (MI_GET_PAGE_COLOR_FROM_SESSION(MmSessionSpace));
}
else {
MI_CAPTURE_DIRTY_BIT_TO_PFN (PointerPte, Pfn1);
CloneBlock = (PMMCLONE_BLOCK) Pfn1->PteAddress;
//
// Get a new page with the same color as this page.
//
NewPageIndex = MiRemoveAnyPage (
MI_PAGE_COLOR_PTE_PROCESS(PageFrameIndex,
&CurrentProcess->NextPageColor));
}
MiInitializeCopyOnWritePfn (NewPageIndex,
PointerPte,
WorkingSetIndex,
WorkingSetList);
UNLOCK_PFN (OldIrql);
InterlockedIncrement (&KeGetCurrentPrcb ()->MmCopyOnWriteCount);
CopyFrom = PAGE_ALIGN (FaultingAddress);
MappingPte = MiReserveSystemPtes (1, SystemPteSpace);
if (MappingPte != NULL) {
MI_MAKE_VALID_KERNEL_PTE (TempPte2,
NewPageIndex,
MM_READWRITE,
MappingPte);
MI_SET_PTE_DIRTY (TempPte2);
if (Pfn1->u3.e1.CacheAttribute == MiNonCached) {
MI_DISABLE_CACHING (TempPte2);
}
else if (Pfn1->u3.e1.CacheAttribute == MiWriteCombined) {
MI_SET_PTE_WRITE_COMBINE (TempPte2);
}
MI_WRITE_VALID_PTE (MappingPte, TempPte2);
CopyTo = MiGetVirtualAddressMappedByPte (MappingPte);
}
else {
CopyTo = MiMapPageInHyperSpace (CurrentProcess,
NewPageIndex,
&OldIrql);
}
KeCopyPage (CopyTo, CopyFrom);
if (MappingPte != NULL) {
MiReleaseSystemPtes (MappingPte, 1, SystemPteSpace);
}
else {
MiUnmapPageInHyperSpace (CurrentProcess, CopyTo, OldIrql);
}
if (!FakeCopyOnWrite) {
//
// If the page was really a copy on write page, make it
// accessed, dirty and writable. Also, clear the copy-on-write
// bit in the PTE.
//
MI_SET_PTE_DIRTY (TempPte);
TempPte.u.Hard.Write = 1;
MI_SET_ACCESSED_IN_PTE (&TempPte, 1);
TempPte.u.Hard.CopyOnWrite = 0;
}
//
// Regardless of whether the page was really a copy on write,
// the frame field of the PTE must be updated.
//
TempPte.u.Hard.PageFrameNumber = NewPageIndex;
//
// If the modify bit is set in the PFN database for the
// page, the data cache must be flushed. This is due to the
// fact that this process may have been cloned and the cache
// still contains stale data destined for the page we are
// going to remove.
//
ASSERT (TempPte.u.Hard.Valid == 1);
MI_WRITE_VALID_PTE_NEW_PAGE (PointerPte, TempPte);
//
// Flush the TB entry for this page.
//
if (SessionSpace == NULL) {
MI_FLUSH_SINGLE_TB (FaultingAddress, FALSE);
//
// Increment the number of private pages.
//
CurrentProcess->NumberOfPrivatePages += 1;
}
else {
MI_FLUSH_SINGLE_TB (FaultingAddress, TRUE);
ASSERT (Pfn1->u3.e1.PrototypePte == 1);
}
//
// Decrement the share count for the page which was copied
// as this PTE no longer refers to it.
//
LOCK_PFN (OldIrql);
MiDecrementShareCount (Pfn1, PageFrameIndex);
if (SessionSpace == NULL) {
CloneDescriptor = MiLocateCloneAddress (CurrentProcess,
(PVOID)CloneBlock);
if (CloneDescriptor != NULL) {
//
// Decrement the reference count for the clone block,
// note that this could release and reacquire the mutexes.
//
MiDecrementCloneBlockReference (CloneDescriptor,
CloneBlock,
CurrentProcess,
NULL,
OldIrql);
}
}
UNLOCK_PFN (OldIrql);
return TRUE;
}