User access to an uncompleted IRP buffer

NTDEV
1

Hi,
I’m trying to evaluate the next scenario:
The user performs a non synchronous ReadFile
to a direct IO device object, the driver receives that
buffer locked via an Mdl.
That IRP is marked pending and a DMA tranfer
writes that buffer, the user is notified (not by completion)
that the buffer is ready and he performs some processing on it
then, the DMA writes it again.
At a later stage the IRP is completed.

All this should be performed while the buffer is still locked and the IRP
is not completed.

Are there any problems to this method ?

thanks,
Tomer Goldberg

2

Hi,

It shud be deterministic. So think in more better way.

 

yatindra

From: “tomerg”

>Reply-To: “Windows System Software Devs Interest List”
>To: “Windows System Software Devs Interest List”
>Subject: [ntdev] User access to an uncompleted IRP buffer
>Date: Sat, 24 Jul 2004 21:41:52 +0200
>
>
>Hi,
>I’m trying to evaluate the next scenario:
>The user performs a non synchronous ReadFile
>to a direct IO device object, the driver receives that
>buffer locked via an Mdl.
>That IRP is marked pending and a DMA tranfer
>writes that buffer, the user is notified (not by completion)
>that the buffer is ready and he performs some processing on it
>then, the DMA writes it again.
>At a later stage the IRP is completed.
>
>All this should be performed while the buffer is still locked and the IRP
>is not completed.
>
>Are there any problems to this method ?
>
>thanks,
>Tomer Goldberg
>—
>Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256
>
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