Re: [PATCH] usb: storage: skip only when uas driver is loaded

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Jul 01, 2019 at 04:48:48PM +0800, JC Kuo wrote:
> When usb-storage driver detects a UAS capable device, it ignores the
> device if CONFIG_USB_UAS is enabled. usb-storage driver assumes uas
> driver certainly will be loaded. However, it's possible that uas
> driver will not be loaded, for example, uas kernel module is not
> installed properly or it is in modprobe blacklist.
> 
> In case of uas driver not being loaded, the UAS capable device will
> not fallback to work at Bulk-only-transfer mode. The device just
> disappears without any notification to user/userspace.
> 
> This commit changes usb-storage driver to skip UAS capable device
> only when uas driver is already loaded to make sure the device will
> at least work with Bulk protocol.

But what happens if the driver is loaded afterward, because 'modprobe'
was called by the driver core (or it should have been, because this is a
device that supports that protocol)?

I think you just broke working systems :(

Why wouldn't the UAS driver get loaded automatically if it is configured
in the system as it is today?

thanks,

greg k-h