If you’re re-entering the FSD from a completion routine, then you must save
the top level IRP field of the thread and set it to NULL before re-entering.
Otherwise, the FSD may access an IRP context structure it stored in the top
level IRP field of the thread. This access wouldn’t be a problem if the FSD
hadn’t freed the IRP context structure before invoking your completion
routine by calling IoCompleteRequest.
Are you setting the top level IRP field of the thread to NULL before
re-entering the FSD from your filter’s completion routine? Jamie’s 90%/10%
success/failure statistics are consistent with statistics I’ve observed when
NOT setting the top level IRP field to NULL before re-entry.
Also, is the machine that is failing an SMP machine? SMP machines under
load exacerbate this bug.
-----Original Message-----
From: Neil Weicher [mailto:xxxxx@netlib.com]
Sent: Sunday, March 12, 2000 12:42 AM
To: File Systems Developers
Cc: Tony Mason
Subject: [ntfsd] RE: page fault from synchronous FSD request in Create
Com pletion routine
Thanks very much for the reply.
<< Given that this is a page fault, is it possible that maybe you have the
address on which it is faulting? >>
The address is an invalid one, usually something like 000000A4h. All the
other pointer values seem valid. I have included the stripped down code
below.
<< Best of luck - trying to debug problems like this via general
descriptions
is (in my experience) a tough thing for this group (or anyone, really) to
accomplish. >>
Understandable. I was just wondering if it struck any familiar note.
The stripped down code is shown below. The file object and device object are
extracted from the appropriate parameters of the Create Completion routine.
The routine below works fine, but then crashes after a number of iterations,
usually at the time of a process change.
Again, many thanks.
Neil
NTSTATUS ReadFile( PDEVICE_OBJECT DeviceObject,
PFILE_OBJECT FileObject,
PUCHAR Buffer,
ULONG Length,
PLARGE_INTEGER Offset )
{
NTSTATUS ntStatus = STATUS_INSUFFICIENT_RESOURCES;
PIRP irp;
KEVENT event;
IO_STATUS_BLOCK ioStatus;
PIO_STACK_LOCATION irpSp;
KeInitializeEvent(&event, NotificationEvent, FALSE);
irp = IoBuildSynchronousFsdRequest (
IRP_MJ_READ, DeviceObject, Buffer, Length, Offset, &event,
&ioStatus );
);
if (irp != NULL)
{
irpSp = IoGetNextIrpStackLocation(irp);
irpSp->FileObject = FileObject;
if ((ntStatus = IoCallDriver(DeviceObject, irp)) == STATUS_PENDING)
{
KeWaitForSingleObject(&event, Suspended, KernelMode, FALSE,
NULL);
ntStatus = ioStatus.Status;
}
}
return (ntStatus);
}
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