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Reduce code duplication in rundown protection
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This commit is contained in:
Aiken Harris
2026-06-22 11:27:31 +02:00
parent e431bccd44
commit 76b1807eee
1 changed files with 4 additions and 77 deletions
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81
xtoskrnl/ex/rundown.cc
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@@ -24,38 +24,8 @@ XTFASTCALL
BOOLEAN BOOLEAN
EX::Rundown::AcquireProtection(IN PEX_RUNDOWN_REFERENCE Descriptor) EX::Rundown::AcquireProtection(IN PEX_RUNDOWN_REFERENCE Descriptor)
{ {
ULONG_PTR CurrentValue, NewValue; /* Acquire protection */
return AcquireProtection(Descriptor, 1);
/* Get current value */
CurrentValue = Descriptor->Count;
/* Main loop execution */
while(TRUE)
{
/* Make sure protection is not active yet */
if(CurrentValue & 0x1)
{
/* Already active, nothing to do */
return FALSE;
}
/* Attempt to increment the usage count */
NewValue = CurrentValue + 2;
/* Exchange the value */
NewValue = (ULONG_PTR)RTL::Atomic::CompareExchangePointer(&Descriptor->Ptr, (PVOID)NewValue,
(PVOID)CurrentValue);
/* Make sure protection acquired */
if(NewValue == CurrentValue)
{
/* Successfully acquired protection */
return TRUE;
}
/* Update value and try once again */
CurrentValue = NewValue;
}
} }
/** /**
@@ -178,51 +148,8 @@ XTFASTCALL
VOID VOID
EX::Rundown::ReleaseProtection(IN PEX_RUNDOWN_REFERENCE Descriptor) EX::Rundown::ReleaseProtection(IN PEX_RUNDOWN_REFERENCE Descriptor)
{ {
ULONG_PTR CurrentValue, NewValue; /* Release protection */
PEX_RUNDOWN_WAIT_BLOCK WaitBlock; ReleaseProtection(Descriptor, 1);
/* Read the current state of the rundown descriptor */
CurrentValue = Descriptor->Count;
/* Enter a CAS loop */
while(TRUE)
{
/* Check if the rundown is currently active */
if(CurrentValue & 0x1)
{
/* Extract the pointer to the wait block */
WaitBlock = (PEX_RUNDOWN_WAIT_BLOCK)(CurrentValue & ~0x1);
/* Decrement the pending reference count */
if(!RTL::Atomic::Decrement64((PLONG_PTR)&WaitBlock->Count))
{
/* Signal the event to wake up the teardown thread */
KE::Event::SetEvent(&WaitBlock->WakeEvent, 0, FALSE);
}
/* Break the loop */
break;
}
else
{
/* Attempt to decrement the usage count */
NewValue = CurrentValue - 2;
/* Exchange the value */
NewValue = (ULONG_PTR)RTL::Atomic::CompareExchangePointer(&Descriptor->Ptr, (PVOID)NewValue,
(PVOID)CurrentValue);
/* Check if the atomic swap succeeded without interference from other processors */
if(NewValue == CurrentValue)
{
/* Reference count is decremented, break the loop */
break;
}
/* Collision detected, update current state and retry */
CurrentValue = NewValue;
}
}
} }
/** /**