IQueueCallbackIoCanceledOnQueue::OnIoCanceledOnQueue method

[Applies to UMDF 1.x only]

A driver's OnIoCanceledOnQueue event callback function informs the driver that an I/O request was canceled while it was in an I/O queue.

Syntax


void OnIoCanceledOnQueue(
  [in] IWDFIoQueue   *pWdfQueue,
  [in] IWDFIoRequest *pWdfRequest
);

Parameters

pWdfQueue [in]

A pointer to the IWDFIoQueue interface for the I/O queue that the I/O request was in when it was canceled.

pWdfRequest [in]

A pointer to the IWDFIoRequest interface for the I/O request.

Return value

None.

Remarks

A driver registers an I/O queue's IQueueCallbackIoCanceledOnQueue interface and OnIoCanceledOnQueue callback function when the driver calls the IWDFDevice::CreateIoQueue. For more information about how to register the interface, see IQueueCallbackIoCanceledOnQueue.

If a driver registers an OnIoCanceledOnQueue callback function for an I/O queue, the framework calls the callback function if a request handler receives an I/O request from an I/O queue, the driver calls IWDFIoRequest::ForwardToIoQueue or IWDFIoRequest2::Requeue to requeue the request to the I/O queue for which the OnIoCanceledOnQueue callback function is registered, and the associated I/O operation is subsequently canceled.

After the framework calls the OnIoCanceledOnQueue callback function, the driver owns the request object and, therefore, must cancel the request.

The framework does not call the driver's OnIoCanceledOnQueue callback function for I/O requests that the framework has never delivered to the driver.

The framework calls an OnIoCanceledOnQueue callback function as soon as it determines that an I/O request has been canceled, regardless of the dispatching method that the driver has set for the I/O queue. Therefore, the framework can call an OnIoCanceledOnQueue callback function for a request in a queue that uses sequential dispatching, even if the driver currently owns another request from the queue.

For more information about the OnIoCanceledOnQueue callback function, see Canceling I/O Requests.

Requirements

Target platform

Desktop

End of support

Unavailable in UMDF 2.0 and later.

Minimum UMDF version

1.9

Header

Wudfddi.h (include Wudfddi.h)

See also

IQueueCallbackIoCanceledOnQueue
IWDFDevice::CreateIoQueue
IWDFIoRequest::ForwardToIoQueue

 

 

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