IWDFIoRequest2::Requeue method (wudfddi.h)

[Warning: UMDF 2 is the latest version of UMDF and supersedes UMDF 1. All new UMDF drivers should be written using UMDF 2. No new features are being added to UMDF 1 and there is limited support for UMDF 1 on newer versions of Windows 10. Universal Windows drivers must use UMDF 2. For more info, see Getting Started with UMDF.]

The Requeue method returns an I/O request to the head of the I/O queue from which it was delivered to the driver.

Syntax

HRESULT Requeue();

Return value

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

This method might return one of the other values that Winerror.h contains.

Remarks

A driver can call Requeue only if it uses the manual dispatching method for the I/O queue.

Examples

The following code example shows a segment of an IQueueCallbackStateChange::OnStateChange callback function. The segment obtains an I/O request from the I/O and then returns the request to the queue.

void 
CMyQueue::OnStateChange(
 __in IWDFIoQueue* pWdfQueue,
 __in WDF_IO_QUEUE_STATE 
 )
{
 HRESULT hr;
 IWDFIoRequest* Request;
...
 //
 // Get the IWDFIoRequest interface of the next request.
 //
 hr = pWdfQueue->RetrieveNextRequest(&Request);
...
 //
 // Declare an IWDFIoRequest2 interface pointer and obtain the
 // IWDFIoRequest2 interface from the IWDFIoRequest interface.
 //
 CComQIPtr<IWDFIoRequest2> r2 = Request;

 //
 // Add code here to determine whether to process or requeue the request.
 //
...
 //
 // Requeue the request.
 //
 hr = r2->Requeue();
 if (FAILED(hr)) goto Error;
...
}

Requirements

See also

IWDFIoQueue::RetrieveNextRequest

IWDFIoRequest2