Re: USB: urb error log during reboot on devices with multiple serial consoles (Linux Kernel version 5.15.71)

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Sep 25, 2025 at 01:29:57AM +0000, Ko, Kang Jun wrote:
> Hello,
> 
> Thank you for the kind response. I've tried updating the kernel version to 6.12.3
> and the same error message still exists during shutdown.
> 
> I understand this is not a bug or a functional issue and the kernel is correctly noting that the hardware is no longer reachable.
>  
> However, I would like to know if canceling the USB messages when the
> hardware has gone away so that the error message doesn't happen is
> something that is considered for future kernel versions.

The "problem" here is that the console does not seem to close the
backing tty device properly.  And that is required so that the usb
driver will shut down the submission of the urbs, which will prevent the
message you see from showing up.

The fact that a console works over a usb-serial device at all is a
wonderful hack.  It was me loosing a bet many years ago that even caused
that code to be written in the first place.  So if this even works is
amazing, a little bit of error messages when the device is yanked from
the system is a small price to pay for this feature :)

thanks,

greg k-h