Calling Filesystem while using resource object.

NTFSD
1

Hi,

I’m using kernel resource for synchronization (ExAcquireResourceSharedLite
etc.)
After Acquiring the resource I need sometime to access the file system
(ZwCreateFile, QueryAttribute etc).

There seems to be a problem doing that while the resource is acquired. The
filesytem call sometimes hang.

Is it related to KeEnterCritical region, required for the resource object?
Could anyone exlpain this?

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2

Yes, calling KeEnterCriticalRegion before calling ZwCreateFile may cause
this to occur. You need to release your lock before calling
ZwCreateFile, then re-acquire it afterward. You may have to perform a
re-lookup of an item on a list (assuming that’s what your lock is
protecting), but this is the correct thing to do.

  • Nick Ryan

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of dan Glazer
Sent: Monday, June 30, 2003 6:11 AM
To: File Systems Developers
Subject: [ntfsd] Calling Filesystem while using resource object.

Hi,

I’m using kernel resource for synchronization
(ExAcquireResourceSharedLite
etc.)
After Acquiring the resource I need sometime to access the
file system
(ZwCreateFile, QueryAttribute etc).

There seems to be a problem doing that while the resource is
acquired. The
filesytem call sometimes hang.

Is it related to KeEnterCritical region, required for the
resource object? Could anyone exlpain this?

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3

Is this resource is acquired in the IRP_MJ_CREATE dispatch routine of a
filesystem filter driver ? If so most likely you are deadlocking yourself
because your call to ZwCreateFile will result in a call to your dispatch
routine

–
Nar Ganapathy
Windows Core OS group
This posting is provided “AS IS” with no warranties, and confers no rights.

“dan Glazer” wrote in message news:xxxxx@ntfsd…
>
> Hi,
>
> I’m using kernel resource for synchronization (ExAcquireResourceSharedLite
> etc.)
> After Acquiring the resource I need sometime to access the file system
> (ZwCreateFile, QueryAttribute etc).
>
> There seems to be a problem doing that while the resource is acquired. The
> filesytem call sometimes hang.
>
> Is it related to KeEnterCritical region, required for the resource object?
> Could anyone exlpain this?
>
> _________________________________________________________________
> Help STOP SPAM with the new MSN 8 and get 2 months FREE*
> http://join.msn.com/?page=features/junkmail
>
>
>
>