EVT_WDF_REQUEST_COMPLETION_ROUTINE callback function

Description

[Applies to KMDF and UMDF]

A driver's CompletionRoutine event callback function executes when another driver completes a specified I/O request.

Parameters

Request [in]

A handle to a framework request object that represents the completed I/O request.

Target [in]

A handle to an I/O target object that represents the I/O target that completed the request.

Params [in]

A pointer to a WDF_REQUEST_COMPLETION_PARAMS structure that contains information about the completed request. See note below regarding validity of the completion parameters.

Context [in]

Driver-supplied context information, which the driver specified in a previous call to WdfRequestSetCompletionRoutine.

Remarks

To register a CompletionRoutine callback function for an I/O request, a driver must call WdfRequestSetCompletionRoutine. For more information about this callback function, see Completing I/O Requests.

The completion parameters structure is fully populated with valid information only if the driver formatted the request by calling one of the following:

• WdfIoTargetFormatXxx methods, for example WdfIoTargetFormatRequestForRead
• WdfUsbTargetDeviceFormatRequestForXxx methods, for example WdfUsbTargetDeviceFormatRequestForString
• WdfUsbTargetPipeFormatRequestForXxx methods, for example WdfUsbTargetPipeFormatRequestForWrite

If the driver formatted the request using either WdfRequestFormatRequestUsingCurrentType or WdfRequestWdmFormatUsingStackLocation, only the IoStatus field in the completion parameters structure is valid.

A KMDF driver's CompletionRoutine can run at IRQL <= DISPATCH_LEVEL regardless of the ExecutionLevel specified in the WDF_OBJECT_ATTRIBUTES structure for the I/O request object.

Examples

The function type is declared in Wdfrequest.h, as follows.

typedef VOID
  (EVT_WDF_REQUEST_COMPLETION_ROUTINE)(
    IN WDFREQUEST  Request,
    IN WDFIOTARGET  Target,
    IN PWDF_REQUEST_COMPLETION_PARAMS  Params,
    IN WDFCONTEXT  Context
    );

To define a CompletionRoutine callback function that is named MyCompletionRoutine, you must first provide a function declaration that SDV and other verification tools require, as follows:

EVT_WDF_REQUEST_COMPLETION_ROUTINE  MyCompletionRoutine;

Then, implement your callback function as follows:

VOID
 MyCompletionRoutine (
    IN WDFREQUEST  Request,
    IN WDFIOTARGET  Target,
    IN PWDF_REQUEST_COMPLETION_PARAMS  Params,
    IN WDFCONTEXT  Context
    )
  {...}

See also

WDF_REQUEST_COMPLETION_PARAMS

WdfRequestSetCompletionRoutine