VOID
NTAPI
KiAdjustQuantumThread(IN PKTHREAD Thread)
{
PKPRCB Prcb = KeGetCurrentPrcb();
PKTHREAD NextThread;
/* Acquire thread and PRCB lock */
KiAcquireThreadLock(Thread);
KiAcquirePrcbLock(Prcb);
/* Don't adjust for RT threads */
if ((Thread->Priority < LOW_REALTIME_PRIORITY) &&
(Thread->BasePriority < (LOW_REALTIME_PRIORITY - 2)))
{
/* Decrease Quantum by one and see if we've ran out */
if (--Thread->Quantum <= 0)
{
/* Return quantum */
Thread->Quantum = Thread->QuantumReset;
/* Calculate new Priority */
Thread->Priority = KiComputeNewPriority(Thread, 1);
/* Check if there's no next thread scheduled */
if (!Prcb->NextThread)
{
/* Select a ready thread and check if we found one */
NextThread = KiSelectReadyThread(Thread->Priority, Prcb);
if (NextThread)
{
/* Set it on standby and switch to it */
NextThread->State = Standby;
Prcb->NextThread = NextThread;
}
}
else
{
/* This thread can be preempted again */
Thread->Preempted = FALSE;
}
}
}
/* Release locks */
KiReleasePrcbLock(Prcb);
KiReleaseThreadLock(Thread);
KiExitDispatcher(Thread->WaitIrql);
}
/*++
* @name KiInsertQueueApc
*
* The KiInsertQueueApc routine queues a APC for execution when the right
* scheduler environment exists.
*
* @param Apc
* Pointer to an initialized control object of type APC for which the
* caller provides the storage.
*
* @param PriorityBoost
* Priority Boost to apply to the Thread.
*
* @return None
*
* @remarks The APC will execute at APC_LEVEL for the KernelRoutine registered,
* and at PASSIVE_LEVEL for the NormalRoutine registered.
*
* Callers of this routine must have locked the dipatcher database.
*
*--*/
VOID
FASTCALL
KiInsertQueueApc(IN PKAPC Apc,
IN KPRIORITY PriorityBoost)
{
PKTHREAD Thread = Apc->Thread;
PKAPC_STATE ApcState;
KPROCESSOR_MODE ApcMode;
PLIST_ENTRY ListHead, NextEntry;
PKAPC QueuedApc;
PKGATE Gate;
NTSTATUS Status;
BOOLEAN RequestInterrupt = FALSE;
/*
* Check if the caller wanted this APC to use the thread's environment at
* insertion time.
*/
if (Apc->ApcStateIndex == InsertApcEnvironment)
{
/* Copy it over */
Apc->ApcStateIndex = Thread->ApcStateIndex;
}
/* Get the APC State for this Index, and the mode too */
ApcState = Thread->ApcStatePointer[(UCHAR)Apc->ApcStateIndex];
ApcMode = Apc->ApcMode;
/* The APC must be "inserted" already */
ASSERT(Apc->Inserted == TRUE);
/* Three scenarios:
* 1) Kernel APC with Normal Routine or User APC = Put it at the end of the List
* 2) User APC which is PsExitSpecialApc = Put it at the front of the List
* 3) Kernel APC without Normal Routine = Put it at the end of the No-Normal Routine Kernel APC list
*/
if (Apc->NormalRoutine)
{
/* Normal APC; is it the Thread Termination APC? */
if ((ApcMode != KernelMode) &&
(Apc->KernelRoutine == PsExitSpecialApc))
{
/* Set User APC pending to true */
Thread->ApcState.UserApcPending = TRUE;
/* Insert it at the top of the list */
InsertHeadList(&ApcState->ApcListHead[ApcMode],
&Apc->ApcListEntry);
}
else
{
/* Regular user or kernel Normal APC */
InsertTailList(&ApcState->ApcListHead[ApcMode],
&Apc->ApcListEntry);
}
}
else
{
/* Special APC, find the last one in the list */
ListHead = &ApcState->ApcListHead[ApcMode];
NextEntry = ListHead->Blink;
while (NextEntry != ListHead)
{
/* Get the APC */
QueuedApc = CONTAINING_RECORD(NextEntry, KAPC, ApcListEntry);
/* Is this a No-Normal APC? If so, break */
if (!QueuedApc->NormalRoutine) break;
/* Move to the previous APC in the Queue */
NextEntry = NextEntry->Blink;
}
/* Insert us here */
InsertHeadList(NextEntry, &Apc->ApcListEntry);
}
/* Now check if the Apc State Indexes match */
if (Thread->ApcStateIndex == Apc->ApcStateIndex)
{
/* Check that the thread matches */
if (Thread == KeGetCurrentThread())
{
/* Sanity check */
ASSERT(Thread->State == Running);
/* Check if this is kernel mode */
if (ApcMode == KernelMode)
{
/* All valid, a Kernel APC is pending now */
Thread->ApcState.KernelApcPending = TRUE;
/* Check if Special APCs are disabled */
if (!Thread->SpecialApcDisable)
{
/* They're not, so request the interrupt */
HalRequestSoftwareInterrupt(APC_LEVEL);
}
}
}
else
{
/* Acquire the dispatcher lock */
KiAcquireDispatcherLock();
/* Check if this is a kernel-mode APC */
if (ApcMode == KernelMode)
{
/* Kernel-mode APC, set us pending */
Thread->ApcState.KernelApcPending = TRUE;
/* Are we currently running? */
if (Thread->State == Running)
{
/* The thread is running, so remember to send a request */
RequestInterrupt = TRUE;
}
else if ((Thread->State == Waiting) &&
(Thread->WaitIrql == PASSIVE_LEVEL) &&
!(Thread->SpecialApcDisable) &&
(!(Apc->NormalRoutine) ||
(!(Thread->KernelApcDisable) &&
!(Thread->ApcState.KernelApcInProgress))))
{
/* We'll unwait with this status */
Status = STATUS_KERNEL_APC;
/* Wake up the thread */
KiUnwaitThread(Thread, Status, PriorityBoost);
}
else if (Thread->State == GateWait)
{
/* Lock the thread */
KiAcquireThreadLock(Thread);
/* Essentially do the same check as above */
if ((Thread->State == GateWait) &&
(Thread->WaitIrql == PASSIVE_LEVEL) &&
!(Thread->SpecialApcDisable) &&
(!(Apc->NormalRoutine) ||
(!(Thread->KernelApcDisable) &&
!(Thread->ApcState.KernelApcInProgress))))
{
/* We were in a gate wait. Handle this. */
DPRINT1("A thread was in a gate wait\n");
/* Get the gate */
Gate = Thread->GateObject;
/* Lock the gate */
KiAcquireDispatcherObject(&Gate->Header);
/* Remove it from the waiters list */
RemoveEntryList(&Thread->WaitBlock[0].WaitListEntry);
/* Unlock the gate */
KiReleaseDispatcherObject(&Gate->Header);
/* Increase the queue counter if needed */
if (Thread->Queue) Thread->Queue->CurrentCount++;
/* Put into deferred ready list with this status */
Thread->WaitStatus = STATUS_KERNEL_APC;
KiInsertDeferredReadyList(Thread);
}
/* Release the thread lock */
KiReleaseThreadLock(Thread);
}
}
else if ((Thread->State == Waiting) &&
(Thread->WaitMode == UserMode) &&
((Thread->Alertable) ||
(Thread->ApcState.UserApcPending)))
{
/* Set user-mode APC pending */
Thread->ApcState.UserApcPending = TRUE;
Status = STATUS_USER_APC;
/* Wake up the thread */
KiUnwaitThread(Thread, Status, PriorityBoost);
}
/* Release dispatcher lock */
KiReleaseDispatcherLockFromDpcLevel();
/* Check if an interrupt was requested */
KiRequestApcInterrupt(RequestInterrupt, Thread->NextProcessor);
}
}
}
VOID
NTAPI
KiQuantumEnd(VOID)
{
PKPRCB Prcb = KeGetCurrentPrcb();
PKTHREAD NextThread, Thread = Prcb->CurrentThread;
/* Check if a DPC Event was requested to be signaled */
if (InterlockedExchange(&Prcb->DpcSetEventRequest, 0))
{
/* Signal it */
KeSetEvent(&Prcb->DpcEvent, 0, 0);
}
/* Raise to synchronization level and lock the PRCB and thread */
KeRaiseIrqlToSynchLevel();
KiAcquireThreadLock(Thread);
KiAcquirePrcbLock(Prcb);
/* Check if Quantum expired */
if (Thread->Quantum <= 0)
{
/* Check if we're real-time and with quantums disabled */
if ((Thread->Priority >= LOW_REALTIME_PRIORITY) &&
(Thread->ApcState.Process->DisableQuantum))
{
/* Otherwise, set maximum quantum */
Thread->Quantum = MAX_QUANTUM;
}
else
{
/* Reset the new Quantum */
Thread->Quantum = Thread->QuantumReset;
/* Calculate new priority */
Thread->Priority = KiComputeNewPriority(Thread, 1);
/* Check if a new thread is scheduled */
if (!Prcb->NextThread)
{
/* Get a new ready thread */
NextThread = KiSelectReadyThread(Thread->Priority, Prcb);
if (NextThread)
{
/* Found one, set it on standby */
NextThread->State = Standby;
Prcb->NextThread = NextThread;
}
}
else
{
/* Otherwise, make sure that this thread doesn't get preempted */
Thread->Preempted = FALSE;
}
}
}
/* Release the thread lock */
KiReleaseThreadLock(Thread);
/* Check if there's no thread scheduled */
if (!Prcb->NextThread)
{
/* Just leave now */
KiReleasePrcbLock(Prcb);
KeLowerIrql(DISPATCH_LEVEL);
return;
}
/* Get the next thread now */
NextThread = Prcb->NextThread;
/* Set current thread's swap busy to true */
KiSetThreadSwapBusy(Thread);
/* Switch threads in PRCB */
Prcb->NextThread = NULL;
Prcb->CurrentThread = NextThread;
/* Set thread to running and the switch reason to Quantum End */
NextThread->State = Running;
Thread->WaitReason = WrQuantumEnd;
/* Queue it on the ready lists */
KxQueueReadyThread(Thread, Prcb);
/* Set wait IRQL to APC_LEVEL */
Thread->WaitIrql = APC_LEVEL;
/* Swap threads */
KiSwapContext(APC_LEVEL, Thread);
/* Lower IRQL back to DISPATCH_LEVEL */
KeLowerIrql(DISPATCH_LEVEL);
}
VOID
FASTCALL
KiDeferredReadyThread(IN PKTHREAD Thread)
{
PKPRCB Prcb;
BOOLEAN Preempted;
ULONG Processor = 0;
KPRIORITY OldPriority;
PKTHREAD NextThread;
/* Sanity checks */
ASSERT(Thread->State == DeferredReady);
ASSERT((Thread->Priority >= 0) && (Thread->Priority <= HIGH_PRIORITY));
/* Check if we have any adjusts to do */
if (Thread->AdjustReason == AdjustBoost)
{
/* Lock the thread */
KiAcquireThreadLock(Thread);
/* Check if the priority is low enough to qualify for boosting */
if ((Thread->Priority <= Thread->AdjustIncrement) &&
(Thread->Priority < (LOW_REALTIME_PRIORITY - 3)) &&
!(Thread->DisableBoost))
{
/* Calculate the new priority based on the adjust increment */
OldPriority = min(Thread->AdjustIncrement + 1,
LOW_REALTIME_PRIORITY - 3);
/* Make sure we're not decreasing outside of the priority range */
ASSERT((Thread->PriorityDecrement >= 0) &&
(Thread->PriorityDecrement <= Thread->Priority));
/* Calculate the new priority decrement based on the boost */
Thread->PriorityDecrement += ((SCHAR)OldPriority - Thread->Priority);
/* Again verify that this decrement is valid */
ASSERT((Thread->PriorityDecrement >= 0) &&
(Thread->PriorityDecrement <= OldPriority));
/* Set the new priority */
Thread->Priority = (SCHAR)OldPriority;
}
/* We need 4 quanta, make sure we have them, then decrease by one */
if (Thread->Quantum < 4) Thread->Quantum = 4;
Thread->Quantum--;
/* Make sure the priority is still valid */
ASSERT((Thread->Priority >= 0) && (Thread->Priority <= HIGH_PRIORITY));
/* Release the lock and clear the adjust reason */
KiReleaseThreadLock(Thread);
Thread->AdjustReason = AdjustNone;
}
else if (Thread->AdjustReason == AdjustUnwait)
{
/* Acquire the thread lock and check if this is a real-time thread */
KiAcquireThreadLock(Thread);
if (Thread->Priority < LOW_REALTIME_PRIORITY)
{
/* It's not real time, but is it time critical? */
if (Thread->BasePriority >= (LOW_REALTIME_PRIORITY - 2))
{
/* It is, so simply reset its quantum */
Thread->Quantum = Thread->QuantumReset;
}
else
{
/* Has the priority been adjusted previously? */
if (!(Thread->PriorityDecrement) && (Thread->AdjustIncrement))
{
/* Yes, reset its quantum */
Thread->Quantum = Thread->QuantumReset;
}
/* Wait code already handles quantum adjustment during APCs */
if (Thread->WaitStatus != STATUS_KERNEL_APC)
{
/* Decrease the quantum by one and check if we're out */
if (--Thread->Quantum <= 0)
{
/* We are, reset the quantum and get a new priority */
Thread->Quantum = Thread->QuantumReset;
Thread->Priority = KiComputeNewPriority(Thread, 1);
}
}
}
/* Now check if we have no decrement and boosts are enabled */
if (!(Thread->PriorityDecrement) && !(Thread->DisableBoost))
{
/* Make sure we have an increment */
ASSERT(Thread->AdjustIncrement >= 0);
/* Calculate the new priority after the increment */
OldPriority = Thread->BasePriority + Thread->AdjustIncrement;
/* Check if this new priority is higher */
if (OldPriority > Thread->Priority)
{
/* Make sure we don't go into the real time range */
if (OldPriority >= LOW_REALTIME_PRIORITY)
{
/* Normalize it back down one notch */
OldPriority = LOW_REALTIME_PRIORITY - 1;
}
/* Check if the priority is higher then the boosted base */
if (OldPriority > (Thread->BasePriority +
Thread->AdjustIncrement))
{
/* Setup a priority decrement to nullify the boost */
Thread->PriorityDecrement = ((SCHAR)OldPriority -
Thread->BasePriority -
Thread->AdjustIncrement);
}
/* Make sure that the priority decrement is valid */
ASSERT((Thread->PriorityDecrement >= 0) &&
(Thread->PriorityDecrement <= OldPriority));
/* Set this new priority */
Thread->Priority = (SCHAR)OldPriority;
}
}
}
else
{
/* It's a real-time thread, so just reset its quantum */
Thread->Quantum = Thread->QuantumReset;
}
/* Make sure the priority makes sense */
ASSERT((Thread->Priority >= 0) && (Thread->Priority <= HIGH_PRIORITY));
/* Release the thread lock and reset the adjust reason */
KiReleaseThreadLock(Thread);
Thread->AdjustReason = AdjustNone;
}
/* Clear thread preemption status and save current values */
Preempted = Thread->Preempted;
OldPriority = Thread->Priority;
Thread->Preempted = FALSE;
/* Queue the thread on CPU 0 and get the PRCB and lock it */
Thread->NextProcessor = 0;
Prcb = KiProcessorBlock[0];
KiAcquirePrcbLock(Prcb);
/* Check if we have an idle summary */
if (KiIdleSummary)
{
/* Clear it and set this thread as the next one */
KiIdleSummary = 0;
Thread->State = Standby;
Prcb->NextThread = Thread;
/* Unlock the PRCB and return */
KiReleasePrcbLock(Prcb);
return;
}
/* Set the CPU number */
Thread->NextProcessor = (UCHAR)Processor;
/* Get the next scheduled thread */
NextThread = Prcb->NextThread;
if (NextThread)
{
/* Sanity check */
ASSERT(NextThread->State == Standby);
/* Check if priority changed */
if (OldPriority > NextThread->Priority)
{
/* Preempt the thread */
NextThread->Preempted = TRUE;
/* Put this one as the next one */
Thread->State = Standby;
Prcb->NextThread = Thread;
/* Set it in deferred ready mode */
NextThread->State = DeferredReady;
NextThread->DeferredProcessor = Prcb->Number;
KiReleasePrcbLock(Prcb);
KiDeferredReadyThread(NextThread);
return;
}
}
else
{
/* Set the next thread as the current thread */
NextThread = Prcb->CurrentThread;
if (OldPriority > NextThread->Priority)
{
/* Preempt it if it's already running */
if (NextThread->State == Running) NextThread->Preempted = TRUE;
/* Set the thread on standby and as the next thread */
Thread->State = Standby;
Prcb->NextThread = Thread;
/* Release the lock */
KiReleasePrcbLock(Prcb);
/* Check if we're running on another CPU */
if (KeGetCurrentProcessorNumber() != Thread->NextProcessor)
{
/* We are, send an IPI */
KiIpiSend(AFFINITY_MASK(Thread->NextProcessor), IPI_DPC);
}
return;
}
}
/* Sanity check */
ASSERT((OldPriority >= 0) && (OldPriority <= HIGH_PRIORITY));
/* Set this thread as ready */
Thread->State = Ready;
Thread->WaitTime = KeTickCount.LowPart;
/* Insert this thread in the appropriate order */
Preempted ? InsertHeadList(&Prcb->DispatcherReadyListHead[OldPriority],
&Thread->WaitListEntry) :
InsertTailList(&Prcb->DispatcherReadyListHead[OldPriority],
&Thread->WaitListEntry);
/* Update the ready summary */
Prcb->ReadySummary |= PRIORITY_MASK(OldPriority);
/* Sanity check */
ASSERT(OldPriority == Thread->Priority);
/* Release the lock */
KiReleasePrcbLock(Prcb);
}
/*
* @implemented
*/
NTSTATUS
NTAPI
NtYieldExecution(VOID)
{
NTSTATUS Status;
KIRQL OldIrql;
PKPRCB Prcb;
PKTHREAD Thread, NextThread;
/* NB: No instructions (other than entry code) should preceed this line */
/* Fail if there's no ready summary */
if (!KiGetCurrentReadySummary()) return STATUS_NO_YIELD_PERFORMED;
/* Now get the current thread, set the status... */
Status = STATUS_NO_YIELD_PERFORMED;
Thread = KeGetCurrentThread();
/* Raise IRQL to synch and get the KPRCB now */
OldIrql = KeRaiseIrqlToSynchLevel();
Prcb = KeGetCurrentPrcb();
/* Now check if there's still a ready summary */
if (Prcb->ReadySummary)
{
/* Acquire thread and PRCB lock */
KiAcquireThreadLock(Thread);
KiAcquirePrcbLock(Prcb);
/* Find a new thread to run if none was selected */
if (!Prcb->NextThread) Prcb->NextThread = KiSelectReadyThread(1, Prcb);
/* Make sure we still have a next thread to schedule */
NextThread = Prcb->NextThread;
if (NextThread)
{
/* Reset quantum and recalculate priority */
Thread->Quantum = Thread->QuantumReset;
Thread->Priority = KiComputeNewPriority(Thread, 1);
/* Release the thread lock */
KiReleaseThreadLock(Thread);
/* Set context swap busy */
KiSetThreadSwapBusy(Thread);
/* Set the new thread as running */
Prcb->NextThread = NULL;
Prcb->CurrentThread = NextThread;
NextThread->State = Running;
/* Setup a yield wait and queue the thread */
Thread->WaitReason = WrYieldExecution;
KxQueueReadyThread(Thread, Prcb);
/* Make it wait at APC_LEVEL */
Thread->WaitIrql = APC_LEVEL;
/* Sanity check */
ASSERT(OldIrql <= DISPATCH_LEVEL);
/* Swap to new thread */
KiSwapContext(APC_LEVEL, Thread);
Status = STATUS_SUCCESS;
}
else
{
/* Release the PRCB and thread lock */
KiReleasePrcbLock(Prcb);
KiReleaseThreadLock(Thread);
}
}
/* Lower IRQL and return */
KeLowerIrql(OldIrql);
return Status;
}
NTSTATUS
NtYieldExecution (
VOID
)
/*++
Routine Description:
This function yields execution to any ready thread for up to one
quantum.
Arguments:
None.
Return Value:
None.
--*/
{
KIRQL OldIrql;
PKTHREAD NewThread;
PRKPRCB Prcb;
NTSTATUS Status;
PKTHREAD Thread;
//
// If no other threads are ready, then return immediately. Otherwise,
// attempt to yield execution.
//
// N.B. The test for ready threads is made outside any synchonization.
// Since this code cannot be perfectly synchronized under any
// conditions the lack of synchronization is of no consequence.
//
if (KiGetCurrentReadySummary() == 0) {
return STATUS_NO_YIELD_PERFORMED;
} else {
Status = STATUS_NO_YIELD_PERFORMED;
Thread = KeGetCurrentThread();
OldIrql = KeRaiseIrqlToSynchLevel();
Prcb = KeGetCurrentPrcb();
if (Prcb->ReadySummary != 0) {
//
// Acquire the thread lock and the PRCB lock.
//
// If a thread has not already been selected for execution, then
// attempt to select another thread for execution.
//
KiAcquireThreadLock(Thread);
KiAcquirePrcbLock(Prcb);
if (Prcb->NextThread == NULL) {
Prcb->NextThread = KiSelectReadyThread(1, Prcb);
}
//
// If a new thread has been selected for execution, then switch
// immediately to the selected thread.
//
if ((NewThread = Prcb->NextThread) != NULL) {
Thread->Quantum = Thread->QuantumReset;
//
// Compute the new thread priority.
//
// N.B. The new priority will never be greater than the previous
// priority.
//
Thread->Priority = KiComputeNewPriority(Thread, 1);
//
// Release the thread lock, set swap busy for the old thread,
// set the next thread to NULL, set the current thread to the
// new thread, set the new thread state to running, set the
// wait reason, queue the old running thread, and release the
// PRCB lock, and swp context to the new thread.
//
KiReleaseThreadLock(Thread);
KiSetContextSwapBusy(Thread);
Prcb->NextThread = NULL;
Prcb->CurrentThread = NewThread;
NewThread->State = Running;
Thread->WaitReason = WrYieldExecution;
KxQueueReadyThread(Thread, Prcb);
Thread->WaitIrql = APC_LEVEL;
ASSERT(OldIrql <= DISPATCH_LEVEL);
KiSwapContext(Thread, NewThread);
Status = STATUS_SUCCESS;
} else {
KiReleasePrcbLock(Prcb);
KiReleaseThreadLock(Thread);
}
}
//
// Lower IRQL to its previous level and return.
//
KeLowerIrql(OldIrql);
return Status;
}
}
VOID
FASTCALL
KeWaitForGate (
__inout PKGATE Gate,
__in KWAIT_REASON WaitReason,
__in KPROCESSOR_MODE WaitMode
)
/*++
Routine Description:
This function waits until the signal state of a gate object is set. If
the state of the gate object is signaled when the wait is executed, then
no wait will occur.
Arguments:
Gate - Supplies a pointer to a dispatcher object of type Gate.
WaitReason - Supplies the reason for the wait.
WaitMode - Supplies the processor mode in which the wait is to occur.
Return Value:
None.
--*/
{
PKTHREAD CurrentThread;
KLOCK_QUEUE_HANDLE LockHandle;
PKQUEUE Queue;
PKWAIT_BLOCK WaitBlock;
NTSTATUS WaitStatus;
ASSERT_GATE(Gate);
ASSERT(KeGetCurrentIrql() <= DISPATCH_LEVEL);
//
// Raise IRQL to SYNCH_LEVEL and acquire the APC queue lock.
//
CurrentThread = KeGetCurrentThread();
do {
KeAcquireInStackQueuedSpinLockRaiseToSynch(&CurrentThread->ApcQueueLock,
&LockHandle);
//
// Test to determine if a kernel APC is pending.
//
// If a kernel APC is pending, the special APC disable count is zero,
// and the previous IRQL was less than APC_LEVEL, then a kernel APC
// was queued by another processor just after IRQL was raised to
// SYNCH_LEVEL, but before the APC queue lock was acquired.
//
// N.B. This can only happen in a multiprocessor system.
//
if (CurrentThread->ApcState.KernelApcPending &&
(CurrentThread->SpecialApcDisable == 0) &&
(LockHandle.OldIrql < APC_LEVEL)) {
//
// Unlock the APC queue lock and lower IRQL to its previous value.
// An APC interrupt will immediately occur which will result in
// the delivery of the kernel APC if possible.
//
KeReleaseInStackQueuedSpinLock(&LockHandle);
continue;
}
//
// If the current thread is associated with a queue object, then
// acquire the dispatcher lock.
//
if ((Queue = CurrentThread->Queue) != NULL) {
KiLockDispatcherDatabaseAtSynchLevel();
}
//
// Acquire the thread lock and the object lock.
//
// If the object is already signaled, then clear the signaled state,
// release the object lock, release the thread lock, and lower IRQL
// to its previous value. Otherwise, set the thread state to gate
// wait, set the address of the gate object, insert the thread in the
// object wait list, set context swap busy, release the object lock,
// release the thread lock, and switch to a new thread.
//
KiAcquireThreadLock(CurrentThread);
KiAcquireKobjectLock(Gate);
if (Gate->Header.SignalState != 0) {
Gate->Header.SignalState = 0;
KiReleaseKobjectLock(Gate);
KiReleaseThreadLock(CurrentThread);
if (Queue != NULL) {
KiUnlockDispatcherDatabaseFromSynchLevel();
}
KeReleaseInStackQueuedSpinLock(&LockHandle);
break;
} else {
WaitBlock = &CurrentThread->WaitBlock[0];
WaitBlock->Object = Gate;
WaitBlock->Thread = CurrentThread;
CurrentThread->WaitMode = WaitMode;
CurrentThread->WaitReason = WaitReason;
CurrentThread->WaitIrql = LockHandle.OldIrql;
CurrentThread->State = GateWait;
CurrentThread->GateObject = Gate;
InsertTailList(&Gate->Header.WaitListHead, &WaitBlock->WaitListEntry);
KiReleaseKobjectLock(Gate);
KiSetContextSwapBusy(CurrentThread);
KiReleaseThreadLock(CurrentThread);
//
// If the current thread is associated with a queue object, then
// activate another thread if possible.
//
if (Queue != NULL) {
if ((Queue = CurrentThread->Queue) != NULL) {
KiActivateWaiterQueue(Queue);
}
KiUnlockDispatcherDatabaseFromSynchLevel();
}
KeReleaseInStackQueuedSpinLockFromDpcLevel(&LockHandle);
WaitStatus = (NTSTATUS)KiSwapThread(CurrentThread, KeGetCurrentPrcb());
if (WaitStatus == STATUS_SUCCESS) {
return;
}
}
} while (TRUE);
return;
}