VOID
FASTCALL
KiQueueReadyThread(IN PKTHREAD Thread,
IN PKPRCB Prcb)
{
/* Call the macro. We keep the API for compatibility with ASM code */
KxQueueReadyThread(Thread, Prcb);
}
VOID
NTAPI
KiDispatchInterrupt(VOID)
{
PKIPCR Pcr = (PKIPCR)KeGetPcr();
PKPRCB Prcb = &Pcr->PrcbData;
PVOID OldHandler;
PKTHREAD NewThread, OldThread;
/* Disable interrupts */
_disable();
/* Check for pending timers, pending DPCs, or pending ready threads */
if ((Prcb->DpcData[0].DpcQueueDepth) ||
(Prcb->TimerRequest) ||
(Prcb->DeferredReadyListHead.Next))
{
/* Switch to safe execution context */
OldHandler = Pcr->NtTib.ExceptionList;
Pcr->NtTib.ExceptionList = EXCEPTION_CHAIN_END;
/* Retire DPCs while under the DPC stack */
//KiRetireDpcListInDpcStack(Prcb, Prcb->DpcStack);
// FIXME!!! //
KiRetireDpcList(Prcb);
/* Restore context */
Pcr->NtTib.ExceptionList = OldHandler;
}
/* Re-enable interrupts */
_enable();
/* Check for quantum end */
if (Prcb->QuantumEnd)
{
/* Handle quantum end */
Prcb->QuantumEnd = FALSE;
KiQuantumEnd();
}
else if (Prcb->NextThread)
{
/* Capture current thread data */
OldThread = Prcb->CurrentThread;
NewThread = Prcb->NextThread;
/* Set new thread data */
Prcb->NextThread = NULL;
Prcb->CurrentThread = NewThread;
/* The thread is now running */
NewThread->State = Running;
OldThread->WaitReason = WrDispatchInt;
/* Make the old thread ready */
KxQueueReadyThread(OldThread, Prcb);
/* Swap to the new thread */
KiSwapContext(APC_LEVEL, OldThread);
}
}
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);
}
/*
* @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;
}
}
