media/doc/irp cancel boilerplate.c

   1
   2
   3 /*
   4 Boiler plate for irp cancelation, for irp queues you manage yourself
   5 -Gunnar
   6 */
   7
   8
   9
  10 CancelRoutine(
  11    DEV_OBJ Dev,
  12    Irp
  13    )
  14 {
  15    //don't need this since we have our own sync. protecting irp cancellation
  16    IoReleaseCancelSpinLock(Irp->CancelIrql);
  17
  18    theLock = Irp->Tail.Overlay.DriverContext[3];
  19
  20    Lock(theLock);
  21    RemoveEntryList(&Irp->Tail.Overlay.ListEntry);
  22    Unlock(theLock);
  23
  24    Irp->IoStatus.Status = STATUS_CANCELLED;
  25    Irp->IoStatus.Information = 0;
  26
  27    IoCompleteRequest(Irp, IO_NO_INCREMENT);
  28
  29 }
  30
  31
  32 QUEUE_BOLIERPLATE
  33 {
  34    Lock(theLock);
  35
  36    Irp->Tail.Overlay.DriverContext[3] = &theLock;
  37
  38    IoSetCancelRoutine(Irp, CancelRoutine);
  39    if (Irp->Cancel && IoSetCancelRoutine(Irp, NULL))
  40    {
  41       /*
  42       Irp has already been cancelled (before we got to queue it),
  43       and we got to remove the cancel routine before the canceler could,
  44       so we cancel/complete the irp ourself.
  45       */
  46
  47       Unlock(theLock);
  48
  49       Irp->IoStatus.Status = STATUS_CANCELLED;
  50       Irp->IoStatus.Information = 0;
  51       IoCompleteRequest(Irp, IO_NO_INCREMENT);
  52
  53       return FALSE;
  54    }
  55
  56    //else were ok
  57
  58
  59    Irp->IoStatus.Status = STATUS_PENDING;
  60    IoMarkIrpPending(Irp);
  61
  62    InsertTailList(Queue);
  63
  64    Unlock(theLock);
  65
  66 }
  67
  68
  69 DEQUEUE_BOILERPLATE
  70 {
  71    Lock(theLock);
  72
  73    Irp = RemoveHeadList(Queue);
  74
  75    if (!IoSetCancelRoutine(Irp, NULL))
  76    {
  77       /*
  78       Cancel routine WILL be called after we release the spinlock. It will try to remove
  79       the irp from the list and cancel/complete this irp. Since we allready removed it,
  80       make its ListEntry point to itself.
  81       */
  82
  83       InitializeListHead(&Irp->Tail.Overlay.ListEntry);
  84
  85       Unlock(theLock);
  86
  87       return;
  88    }
  89
  90
  91    /*
  92    Cancel routine will NOT be called, canceled or not.
  93    The Irp might have been canceled (Irp->Cancel flag set) but we don't care,
  94    since we are to complete this Irp now anyways.
  95    */
  96
  97    Unlock(theLock);
  98
  99    Irp->IoStatus.Status = STATUS_SUCCESS;
 100    Irp->IoStatus.Information = 0;
 101    IoCompleteRequest(Irp, IO_NO_INCREMENT);
 102
 103 }