upstream stable would break ubuntu/xr-usb-serial (deprecated ASYNC flags)

[Kamal Mostafa]

The Ubuntu kernel has carried an out-of-tree driver "ubuntu/xr-usb-serial/" since forever. That driver uses the #define'd constant ASYNCB_INITIALIZED in multiple places, e.g.:

    if (test_bit(ASYNCB_INITIALIZED, &xr_usb_serial->port.flags))

But this recent mainline commit (and all linux-stable's >= 4.14) removes the definition of ASYNCB_INITIALIZED ...

    [mainline] d09845e98a05 tty: actually undefine superseded ASYNC flags

    Some kernel-internal ASYNC flags have been superseded by tty-port flags
    and should no longer be used by kernel drivers.

    Fix the misspelled "__KERNEL__" compile guards which failed their sole
    purpose to break out-of-tree drivers that have not yet been updated.

... Which would make ubuntu/xr-usb-serial/ fail to build (as the upstream commit intends).

To avoid that breakage, the stable backports of [mainline] d09845e98a05 will be omitted from all Ubuntu kernels, pending some other resolution of the problem with ubuntu/xr-usb-serial.

[Colin Finck (colinfinck)]

I had the same problem with that driver and fixed it in the driver.
Feel free to use my patch for that: https://github.com/enlyze/xr-usb-serial/commit/6515173a8b2681fd52cc2747d7282f4e47bdd254

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Brian Murray (brian-murray)]

Ubuntu 21.10 (Impish Indri) has reached end of life, so this bug will not be fixed for that specific release.