[ovs-dev] [PATCH] datapath-windows: Solved BSOD when loading an activated extension

[Nithin Raju]

> On Jan 22, 2015, at 6:12 AM, Sorin Vinturis <svinturis at cloudbasesolutions.com> wrote:
> 
> If the OVS extension was previously enabled and the driver unloaded,
> when the driver is loaded again a BSOD is triggered.
> 
> This happens because the OVS extension registers its FilterXxx routines
> to NDIS, by calling NdisFRegisterFilterDriver, before performing all
> the necessary initialization. Because drivers that call
> NdisFRegisterFilterDriver must be prepared for an immediate call to any
> of their FilterXxx functions.
> 
> The BSOD is triggered because the FilterAttach routine, OvsExtAttach,
> tries to acquire the control lock, when the lock is not yet initialized.
> This happens because the FilterAttach is called before the driver
> finishes initialization, in OvsInit().

Sorin,
Thanks for the patch. This has (had) been an annoying bug.

I was wondering if it would be better to just flip the order of OvsCreateDeviceObject() and NdisFRegisterFilterDriver(). If NdisFRegisterFilterDriver() fails, it would be safe to call OvsDeleteDeviceObject().

I don’t have a strong preference, but the change would be make all of the OVS initialization code in one place rather than spread across 2 separate functions.

thanks,
-- Nithin