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FltCbdqInsertIo: Query about return value
Sujay_Upasani
Member Posts: 14
Hello,
From MSDN documentation:
FltCbdqInsertIo returns STATUS_SUCCESS or an appropriate NTSTATUS value such as one of the following:
STATUS_PENDING: The callback data structure was inserted into the callback data queue.
From the documentation, it looks like STATUS_SUCCESS and STATUS_PENDING have the same meaning. Can somebody please clarify this?
Thanks.
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Comments
Check return status with nt_success macro.
Success and pending both successful return statuses.
I would say that the documentation needs a case raised against it. But blindly speaking I would say that
STATUS_PENDINGmeans that you do not own the CBD anymore (because it has been queued)STATUS_SUCCESSmeans that some other condition means "it worked" but you do own the CBDI cannot imagine for a minute what could cause the second bullet - which is why I would say that the documentation is incorrect. At the very best it needs to be clarified. I have never used this API and if I ever did I would actually add an assert against STATUS_SUCCESS (because I think its a meaningless return status) and treat it like STATUS_PENDING
It is interesting that cancelsafe sample checks directly for STATUS_SUCCESS and treats any over return status as failure
I thought I could provide some insight into this. But the more I looked into it, the more confused I got.
So, yeah... I've got nothin'
Peter
Peter Viscarola
OSR
@OSRDrivers
Hello All,
Thanks for the reply.
If FltCbdqInsertIo succeeds, I will return FLT_PREOP_PENDING from pre-callback and later after processing of queue, FltCompletePendedPreOperation will be called to resume processing of an I/O.
Till now, I found that FltCbdqInsertIo returning STATUS_SUCCESS(also, cancelsafe sample checks for STATUS_SUCCESS only). So if FltCbdqInsertIo returns STATUS_PENDING, can we consider it as a success(The callback data structure was inserted into the callback data queue) and return FLT_PREOP_PENDING from pre-callback or treat it as a failure like cancelsafe sample does?
Thanks.
So confusing....
FltCbdqInsertIo just calls IoCsqInsertIrpEx, which is documented to return either STATUS_SUCCESS or the result of the CsqInsertIrpEx callback. Presumably (though I have not confirmed) the latter would be the result of your insert callback specified in the call to FltCbdqInitialize.
In the end, I would say the docs are misleading by suggesting STATUS_PENDING as a possible result and it's safe to just use NT_SUCCESS(status).
-scott
OSR
Hello Scott, thanks for the suggestion.