KSDDKAPI PIRP NTAPI KsRemoveIrpFromCancelableQueue	(	IN OUT PLIST_ENTRY	QueueHead,
		IN PKSPIN_LOCK	SpinLock,
		IN KSLIST_ENTRY_LOCATION	ListLocation,
		IN KSIRP_REMOVAL_OPERATION	RemovalOperation
	)

Definition at line 1370 of file irp.c.

Referenced by IKsPin_PrepareStreamHeader().

{
    PIRP Irp;
    PLIST_ENTRY CurEntry;
    KIRQL OldIrql;

    DPRINT("KsRemoveIrpFromCancelableQueue ListHead %p SpinLock %p ListLocation %x RemovalOperation %x\n", QueueHead, SpinLock, ListLocation, RemovalOperation);

    /* check parameters */
    if (!QueueHead || !SpinLock)
        return NULL;

    /* check if parameter ListLocation is valid */
    if (ListLocation != KsListEntryTail && ListLocation != KsListEntryHead)
        return NULL;

    /* acquire list lock */
    KeAcquireSpinLock(SpinLock, &OldIrql);

    /* point to queue head */
    CurEntry = QueueHead;

    do
    {
        /* reset irp to null */
        Irp = NULL;

        /* iterate to next entry */
        if (ListLocation == KsListEntryHead)
            CurEntry = CurEntry->Flink;
        else
            CurEntry = CurEntry->Blink;

        /* is the end of list reached */
        if (CurEntry == QueueHead)
        {
            /* reached end of list */
            break;
        }

        /* get irp offset */
        Irp = (PIRP)CONTAINING_RECORD(CurEntry, IRP, Tail.Overlay.ListEntry);

        if (Irp->Cancel)
        {
            /* irp has been canceled */
            break;
        }

        if (Irp->CancelRoutine)
        {
            /* remove cancel routine */
            Irp->CancelRoutine = NULL;

            if (RemovalOperation == KsAcquireAndRemove || RemovalOperation == KsAcquireAndRemoveOnlySingleItem)
            {
                /* remove irp from list */
                RemoveEntryList(&Irp->Tail.Overlay.ListEntry);
            }

            if (RemovalOperation == KsAcquireAndRemoveOnlySingleItem || RemovalOperation == KsAcquireOnlySingleItem)
                break;
        }

    }while(TRUE);

    /* release lock */
    KeReleaseSpinLock(SpinLock, OldIrql);

    if (!Irp || Irp->CancelRoutine == NULL)
    {
        /* either an irp has been acquired or nothing found */
        return Irp;
    }

    /* time to remove the canceled irp */
    IoAcquireCancelSpinLock(&OldIrql);
    /* acquire list lock */
    KeAcquireSpinLockAtDpcLevel(SpinLock);

    if (RemovalOperation == KsAcquireAndRemove || RemovalOperation == KsAcquireAndRemoveOnlySingleItem)
    {
        /* remove it */
        RemoveEntryList(&Irp->Tail.Overlay.ListEntry);
    }

    /* release list lock */
    KeReleaseSpinLockFromDpcLevel(SpinLock);

    /* release cancel spinlock */
    IoReleaseCancelSpinLock(OldIrql);
    /* no non canceled irp has been found */
    return NULL;
}

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