IoGetAttachedDeviceReference

The IoGetAttachedDeviceReference routine returns a pointer to the highest level device object in a driver stack and increments the reference count on that object.

PDEVICE_OBJECT
  IoGetAttachedDeviceReference(
    IN PDEVICE_OBJECT  DeviceObject
    );

Parameters

DeviceObject

Pointer to the device object for which the topmost attached device object is retrieved.

Return Value

IoGetAttachedDeviceReference returns a pointer to the highest level device object in a stack of attached device objects after incrementing the reference count on the object.

Headers

Declared in wdm.h and ntddk.h. Include wdm.h or ntddk.h.

Comments

If the device object at DeviceObject has no device objects attached to it, DeviceObject and the returned pointer are equal.

Device driver writers must ensure that when they have completed all operations that required them to make this call, that they call ObDereferenceObject with the device object pointer returned by this routine. Failure to do so will prevent the system from freeing or deleting the device object because of an outstanding reference count.

Callers of this routine must be running at IRQL <= DISPATCH_LEVEL.

See Also

ObDereferenceObject