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IoGetAttachedDeviceReference routine

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

Syntax


PDEVICE_OBJECT IoGetAttachedDeviceReference(
  _In_  PDEVICE_OBJECT DeviceObject
);

Parameters

DeviceObject [in]

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.

Remarks

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.

Requirements

Version

Available starting with Windows 2000.

Header

Wdm.h (include Wdm.h, Ntddk.h, or Ntifs.h)

Library

Ntoskrnl.lib

IRQL

<= DISPATCH_LEVEL

DDI compliance rules

DanglingDeviceObjectReference, HwStorPortProhibitedDDIs

See also

ObDereferenceObject

 

 

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