WdfIoQueueRetrieveNextRequest function (wdfio.h)

Article
04/18/2022

[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

[in] Queue

A handle to a framework queue object.

[out] OutRequest

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 code	Description
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

Requirement	Value
Target Platform	Universal
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(kmdf), DriverCreate(kmdf), KmdfIrql(kmdf), KmdfIrql2(kmdf), KmdfIrqlExplicit(kmdf), wdfioqueueretrievenextrequest, WdfIoQueueRetrieveNextRequest(kmdf)

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