Re: [PATCH net,stable] qmi_wwan: do not steal interfaces from class drivers

[David Miller <davem@davemloft.net>]

From: Bjørn Mork <bjorn@mork.no>
Date: Wed,  2 May 2018 22:22:54 +0200

> The USB_DEVICE_INTERFACE_NUMBER matching macro assumes that
> the { vendorid, productid, interfacenumber } set uniquely
> identifies one specific function.  This has proven to fail
> for some configurable devices. One example is the Quectel
> EM06/EP06 where the same interface number can be either
> QMI or MBIM, without the device ID changing either.
> 
> Fix by requiring the vendor-specific class for interface number
> based matching.  Functions of other classes can and should use
> class based matching instead.
> 
> Fixes: 03304bcb5ec4 ("net: qmi_wwan: use fixed interface number matching")
> Signed-off-by: Bjørn Mork <bjorn@mork.no>
> ---
> It's quite possible that the fix should be integrated in the
> USB_DEVICE_INTERFACE_NUMBER macro instead.  But that has grown a few
> other users since it was added, so changing it now seems risky. 
> Another option is of course adding a new match macro with the
> USB_CLASS_VENDOR_SPEC match integrated. Maybe best?
> 
> But I'm proposing this as-is for now, since this quickfix seems most
> suitable for stable backporting.

Yes, this simpler approache is better for net and -stable.

Applied.

If you want to do something more sophisticated, that can be done
in net-next.

Thanks.