WdfIoQueueRetrieveNextRequest method

[Applies to KMDF and UMDF]

The WdfIoQueueRetrieveNextRequest method retrieves the next available I/O request from a specified I/O queue.

Syntax


NTSTATUS WdfIoQueueRetrieveNextRequest(
  [in]   WDFQUEUE Queue,
  [out]  WDFREQUEST *OutRequest
);

Parameters

Queue [in]

A handle to a framework queue object.

OutRequest [out]

A pointer to a location that receives a handle to a framework request object. If the queue is empty or the last request has been retrieved, this parameter receives NULL.

Return value

WdfIoQueueRetrieveNextRequest returns STATUS_SUCCESS if the operation succeeds. Otherwise, this method might return one of the following values:

Return codeDescription
STATUS_INVALID_PARAMETER

The driver supplied an invalid handle.

STATUS_NO_MORE_ENTRIES

The framework reached the end of the I/O queue.

STATUS_INVALID_DEVICE_STATE

The specified I/O queue is configured for the parallel dispatching method.

STATUS_WDF_PAUSED

The specified I/O queue is power-managed and its device is in a low-power state, or the specified queue is stopped.

 

This method also might return other NTSTATUS values.

A bug check occurs if the driver supplies an invalid object handle.

Remarks

If a driver configures an I/O queue for manual dispatching of I/O requests, the driver typically calls WdfIoQueueRetrieveNextRequest to obtain requests from the queue. A driver that has configured an I/O queue for sequential dispatching might also call WdfIoQueueRetrieveNextRequest. For more information about using WdfIoQueueRetrieveNextRequest with the manual or sequential dispatching methods, see Dispatching Methods for I/O Requests.

After calling WdfIoQueueRetrieveNextRequest to obtain an I/O request, the driver owns the request and must process the I/O request in some manner.

For more information about the WdfIoQueueRetrieveNextRequest method, see Managing I/O Queues.

Examples

The following code example obtains a handle to the next request object that is contained in a device's I/O queue.


NTSTATUS  status;
WDFREQUEST  request;

status = WdfIoQueueRetrieveNextRequest(
                                       pDeviceContext->ReadQueue,
                                       &request
                                       );

Requirements

Minimum KMDF version

1.0

Minimum UMDF version

2.0

Header

Wdfio.h (include Wdf.h)

Library

Wdf01000.sys (KMDF);
WUDFx02000.dll (UMDF)

IRQL

<= DISPATCH_LEVEL

DDI compliance rules

DoubleCompletion, DriverCreate, KmdfIrql, KmdfIrql2, wdfioqueueretrievenextrequest

See also

WdfIoQueueRetrieveFoundRequest
WdfIoQueueRetrieveRequestByFileObject

 

 

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