What is cancelable IRP

NTDEV
1

Dear all
what is cancelable IRP? If my WDM driver don’t set cancel routine, can this IRP can be canceled in my driver?

thank you very much.

Denny

2

If you do not set a cancel routine, the irp can be canceled (Irp->Cancel is set to TRUE) but you will not be notified of it being canceled when it changes state. you can occasionally check Irp->Cancel if you support canceling an irp that is being processed, otherwise if you know your processing will deterministically complete the request you can skip checking the Cancel field. If the request is not being processed and is in a queue of work to do in the future, you should definitely set a cancel routine. In KMDF this is very easy, in WDM you can use a IO CSQ

d

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Sent: Wednesday, March 04, 2009 7:36 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] What is cancelable IRP

Dear all
what is cancelable IRP? If my WDM driver don’t set cancel routine, can this IRP can be canceled in my driver?

thank you very much.

Denny

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