[Bug 1916418] Re: Custom properties set with ENV{WHATEVER} in parent no longer imported with IMPORT{parent} in udev rule

[Brian Murray]

** Changed in: systemd (Ubuntu)
    Milestone: None => hirsute-updates

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Title:
  Custom properties set with ENV{WHATEVER} in parent no longer imported
  with IMPORT{parent} in udev rule

Status in systemd package in Ubuntu:
  New
Status in systemd source package in Focal:
  Invalid
Status in systemd source package in Groovy:
  New

Bug description:
  DisplayLink uses these udev rules to start the displaylink service
  when a displaylink device is plugged in:

  ACTION=="add", SUBSYSTEM=="usb", DRIVERS=="usb",
  ATTR{idVendor}=="17e9", IMPORT{builtin}="usb_id",
  ENV{DISPLAYLINK_DEVNAME}="$env{DEVNAME}",
  ENV{DISPLAYLINK_DEVICE_ID}="$env{ID_BUS}-$env{BUSNUM}-$env{DEVNUM}-$env{ID_SERIAL}",
  ENV{REMOVE_CMD}="/opt/displaylink/udev.sh $root
  $env{DISPLAYLINK_DEVICE_ID} $env{DISPLAYLINK_DEVNAME}"

  ACTION=="add", SUBSYSTEM=="usb", DRIVERS=="usb",
  ATTRS{idVendor}=="17e9", ATTR{bInterfaceClass}=="ff",
  ATTR{bInterfaceProtocol}=="03", IMPORT{parent}="DISPLAYLINK*",
  RUN+="/opt/displaylink/udev.sh $root $env{DISPLAYLINK_DEVICE_ID}
  $env{DISPLAYLINK_DEVNAME}"

  The important thing to note here is that the first rule is for the
  device that is the parent of the device triggers the second rule, and
  the first rule sets ENV{DISPLAYLINK_DEVNAME} and
  ENV{DISPLAYLINK_DEVICE_ID}, and the second rule attempts to import
  them with IMPORT{parent} and then use them.

  This worked fine in 20.04.

  It does not work in 21.04.

  When the second rule is triggered, DISPLAYLINK_DEVICE_ID and
  DISPLAYLINK_DEVNAME are not set.

  I have confirmed via udevadm monitor that the variables are getting
  set on the parent.

  I have confirmed via udevadm info --attribute-walk that the device
  triggering the second rule is the child of the device triggering the
  first one.

  I have tried to import the variables explicitly instead of using a
  glob pattern and that doesn't work either.

  When I modify the rule to import DEVNAME, ID_BUS, BUSNUM, DEVNUM, and
  ID_SERIAL directly, that works. The problem appears to be that these
  custom properties we are setting in the parent can't be imported in
  the child.

  ProblemType: Bug
  DistroRelease: Ubuntu 21.04
  Package: udev 247.3-1ubuntu2
  ProcVersionSignature: Ubuntu 5.10.0-14.15-generic 5.10.11
  Uname: Linux 5.10.0-14-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.20.11-0ubuntu59
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CurrentDesktop: ubuntu:GNOME
  CustomUdevRuleFiles: 60-brother-libsane-type1.rules 99-displaylink.rules~ 70-snap.core.rules 70-snap.snap-store.rules 99-x10.rules 60-brother-brscan4-libsane-type1.rules 50-yubikey.rules 70-snap.canonical-livepatch.rules 70-snap.gnome-system-monitor.rules 70-snap.chromium.rules 99-displaylink.rules
  Date: Sun Feb 21 19:21:20 2021
  InstallationDate: Installed on 2019-01-02 (781 days ago)
  InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
  MachineType: Acer Predator G6-710
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.10.0-14-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash vt.handoff=7
  SourcePackage: systemd
  UpgradeStatus: Upgraded to hirsute on 2021-02-21 (0 days ago)
  dmi.bios.date: 05/18/2016
  dmi.bios.release: 5.11
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: R01-A4
  dmi.board.name: Predator G6-710
  dmi.board.vendor: Acer
  dmi.chassis.type: 3
  dmi.chassis.vendor: Acer
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrR01-A4:bd05/18/2016:br5.11:svnAcer:pnPredatorG6-710:pvr:rvnAcer:rnPredatorG6-710:rvr:cvnAcer:ct3:cvr:
  dmi.product.family: Acer Desktop
  dmi.product.name: Predator G6-710
  dmi.sys.vendor: Acer

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