[vbox-dev] IoGetDeviceObjectPointer hangs vboxusbmon

[Ribhi Kamal]

The hubwalker loops through PDO devices 0-15 and it hangs at number 11. So
the device name (hub name) should be "\Device\USBPDO-11". Is that what you
wanted?

I'm still trying to figure out how to step through assembly code in windbg.
I just started windows in debug mode and connected windbg.

In the mean time, I found the link below which suggests queuing a work item
to call IoGetDeviceObjectPointer using ioallocateworkitem routine, should I
give that a try?
http://www.osronline.com/article.cfm?id=24

Here is a little snippet:

*Figure 5 – The wrong way to write a PnP Notification Callback*

* *

And, while you’d be partially right, you *do* get a pointer to a device
object using its name by calling *IoGetDeviceObject Pointer*, you’d also
get bitten by one of the conditions of PnP Notification routines.  As it
very clearly states in the documentation:



*A callback routine must not open the device directly. If the provider of
the interface causes blocking PnP events, the notification callback routine
can cause a deadlock if it tries to open the device in the callback thread.*

* *

When you call *IoGetDeviceObjectPointer, *you’re actually issuing an open
(IRP_MJ_CREATE) for the specified device.  That’s why you get back a File
Object pointer, in addition to the Device Object pointer that you
wanted.  So, the proper thing to do is queue a work item that does the call
to *IoGetDeviceObjectPointer*, as shown in *Figure 6*.


On Tue, Mar 13, 2012 at 2:10 PM, Huihong Luo <huisinro at yahoo.com> wrote:

> This api simply returns a device object from a name, and usually does not
> block. What is the
> device name? you can examine ObjectName unicode string.
>
> IoGetDeviceObjectPointer() does the following thing:
>
> ZwOpenFile(ObjectName) to get a handle
> ObReferenceObjectByHandle(handle) to get the FileObject
> IoGetRelatedDeviceObject(FileObject) to get the device object
>
> you can further step into the assembly code to nail down which function
> call causes the lock.
>
> you can also list all locks using these commands in windbg:
>
> !locks
> !deadlock
>
> --- On *Tue, 3/13/12, Ribhi Kamal <rbhkamal at gmail.com>* wrote:
>
>
> From: Ribhi Kamal <rbhkamal at gmail.com>
> Subject: Re: [vbox-dev] IoGetDeviceObjectPointer hangs vboxusbmon
> To: "vbox-dev" <vbox-dev at virtualbox.org>
> Date: Tuesday, March 13, 2012, 10:49 AM
>
>
> Sorry, actually the IRQL == PASSIVE_LEVEL is okay. So just ignore that bit.
>
> On Tue, Mar 13, 2012 at 1:27 PM, Ribhi Kamal <rbhkamal at gmail.com<http://us.mc1603.mail.yahoo.com/mc/compose?to=rbhkamal@gmail.com>
> > wrote:
>
>  I've been troubleshooting an issue that prevents vbox from capturing USB
> devices when other specific USB devices are plugged in (i.e. Sprint USB
> crap). I finally managed to track down the problem to
> IoGetDeviceObjectPointer in VboxUsbMonHubDevWalk. IoGetDeviceObjectPointer
> was getting called, however, it never returned.
>
> I'm not an expert in windows driver development so I'd like to run things
> by you before I start fixing it.
>
> Firstly, I'm not really sure why it hangs (deadlocks?) there for some
> devices and not others. However, I believe that it may be due to the fact
> that some driver interfaces cause blocking PnP events. Due to that,
> vboxusbmon runs into a deadlock when executing IoGetDeviceObjectPointer
> because it is being used directly from a callback function,
> VBoxUsbMonDeviceControl, and IRQL==PASSIVE_LEVEL.
>
> What led me to that conclusion is that right after
> IoGetDeviceObjectPointer is executed, I start seeing lots of PnP events.
>  USBMon::vboxUsbMonHubDevWalk:
> IoGetDeviceObjectPointer - Starting
>
> USBMon::VBoxUsbMonPnPHook:
> VBoxUsbMonPnPHook In
>
> USBMon::VBoxUsbMonPnPHook:
> ==>PnP: Mn(IRP_MN_QUERY_DEVICE_RELATIONS), PDO(0x8833d028),
> IRP(0x882a71a8), Status(0xc00000bb)
>
> See attached for complete debug view.
>
> Are my assumptions correct? If so how would you go about fixing the
> problem.
>
> Thanks!
>
> --
> -- Ribhi
>
>
>
>
> --
> -- Ribhi
>
> -----Inline Attachment Follows-----
>
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>


-- 
-- Ribhi
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