/*++
* @name ExTimedWaitForUnblockPushLock
*
* The ExTimedWaitForUnblockPushLock routine waits for a pushlock
* to be unblocked, for a specified internal.
*
* @param PushLock
* Pointer to a pushlock whose waiter list needs to be optimized.
*
* @param WaitBlock
* Pointer to the pushlock's wait block.
*
* @param Timeout
* Amount of time to wait for this pushlock to be unblocked.
*
* @return STATUS_SUCCESS is the pushlock is now unblocked, otherwise the error
* code returned by KeWaitForSingleObject.
*
* @remarks If the wait fails, then a manual unblock is attempted.
*
*--*/
NTSTATUS
FASTCALL
ExTimedWaitForUnblockPushLock(IN PEX_PUSH_LOCK PushLock,
IN PVOID WaitBlock,
IN PLARGE_INTEGER Timeout)
{
NTSTATUS Status;
/* Initialize the wait event */
KeInitializeEvent(&((PEX_PUSH_LOCK_WAIT_BLOCK)WaitBlock)->WakeEvent,
SynchronizationEvent,
FALSE);
#ifdef CONFIG_SMP
/* Spin on the push lock if necessary */
if (ExPushLockSpinCount)
{
ULONG i = ExPushLockSpinCount;
do
{
/* Check if we got lucky and can leave early */
if (!(*(volatile LONG *)&((PEX_PUSH_LOCK_WAIT_BLOCK)WaitBlock)->Flags & EX_PUSH_LOCK_WAITING))
return STATUS_SUCCESS;
YieldProcessor();
} while (--i);
}
#endif
/* Now try to remove the wait bit */
if (InterlockedBitTestAndReset(&((PEX_PUSH_LOCK_WAIT_BLOCK)WaitBlock)->Flags,
EX_PUSH_LOCK_FLAGS_WAIT_V))
{
/* Nobody removed it already, let's do a full wait */
Status = KeWaitForSingleObject(&((PEX_PUSH_LOCK_WAIT_BLOCK)WaitBlock)->
WakeEvent,
WrPushLock,
KernelMode,
FALSE,
Timeout);
/* Check if the wait was satisfied */
if (Status != STATUS_SUCCESS)
{
/* Try unblocking the pushlock if it was not */
ExfUnblockPushLock(PushLock, WaitBlock);
}
}
else
{
/* Someone beat us to it, no need to wait */
Status = STATUS_SUCCESS;
}
/* Return status */
return Status;
}
NTKERNELAPI
NTSTATUS
FASTCALL
ExTimedWaitForUnblockPushLock (
__inout PEX_PUSH_LOCK PushLock,
__inout PEX_PUSH_LOCK_WAIT_BLOCK WaitBlock,
__in_opt PLARGE_INTEGER Timeout
)
{
ULONG i;
NTSTATUS Status;
UNREFERENCED_PARAMETER (PushLock);
KeInitializeEvent (&WaitBlock->WakeEvent, SynchronizationEvent, FALSE);
for (i = ExPushLockSpinCount; i > 0; i--) {
if (((*(volatile LONG *)&WaitBlock->Flags)&EX_PUSH_LOCK_FLAGS_SPINNING) == 0) {
return STATUS_SUCCESS;
}
KeYieldProcessor ();
}
if (InterlockedBitTestAndReset (&WaitBlock->Flags, EX_PUSH_LOCK_FLAGS_SPINNING_V)) {
Status = KeWaitForSingleObject (&WaitBlock->WakeEvent,
WrPushLock,
KernelMode,
FALSE,
Timeout);
if (Status != STATUS_SUCCESS) {
ExfUnblockPushLock (PushLock,
WaitBlock);
}
} else {
Status = STATUS_SUCCESS;
}
return Status;
}
VOID KphUnlockHandleTableEntry(
__in PHANDLE_TABLE HandleTable,
__in PHANDLE_TABLE_ENTRY HandleTableEntry
)
{
PEX_PUSH_LOCK handleContentionEvent;
PAGED_CODE();
// Set the unlocked bit.
#ifdef _M_X64
InterlockedExchangeAdd64(&HandleTableEntry->Value, 1);
#else
InterlockedExchangeAdd(&HandleTableEntry->Value, 1);
#endif
// Allow waiters to wake up.
handleContentionEvent = (PEX_PUSH_LOCK)((ULONG_PTR)HandleTable + KphDynHtHandleContentionEvent);
if (*(PULONG_PTR)handleContentionEvent != 0)
ExfUnblockPushLock(handleContentionEvent, NULL);
}
