[Bug 1837700] Re: Dell system takes a long time to connect network with external dock

[Che Cheng]

Need fix landing in bionic before 31st of August.

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Title:
  Dell system takes a long time to connect network with external dock

Status in HWE Next:
  New
Status in OEM Priority Project:
  In Progress
Status in systemd package in Ubuntu:
  New
Status in systemd source package in Bionic:
  Fix Committed
Status in systemd source package in Disco:
  New

Bug description:
  update for SRU process:

  [Impact]
  1. On system featured mac passthrough, e.g., Dell/Lenovo laptop, or system occasionally install two USB ethernet with same MAC address, the system will suffer 90 seconds for network interface renaming mechanism before the last USB ethernet interface to activate.

  [Test Case]
  1. Install ubuntu on Dell laptop.
  2. Connect the Dell laptop with two Realtek 8153 USB ethernet dongle. Users can observe the last one will take 90 seconds for renaming to rename0.
  3. Users can also find that the two USB ethernet have the same MAC address.

  [Regression Potential] 
  To resolve the issue, drop a debian patch from systemd package. The debian patch is to revert an upstream commit to support 75-persistent-net-generator.rules udev rule. Since the udev rule is deprecated, the regression potential should be relatively low.

  -----------------------------------

  
  Dell has a feature called MAC addrss passthrough[1] that would force usb ethernet adapters to be assigned with a predefined MAC address stored in BIOS or so. This feature has been landed to mainline kernel in driver r8152[2]. So whenever a r8152 managed device is plugged into Dell devices with MAC addrss passthrough enabled, this driver will set NIC MAC to a predefined one.

  And some Dell devices have already one built-in r8152 NIC port. On
  these devices, when a second r8152 NIC is plugged in, a Debian
  originated udev rules file 73-usb-net-by-mac.rules[3] will invoke udev
  built-in command `net_id` to give a persistent name, and that will be
  based on MAC address. However, since the system has already
  initialized the built-in r8152 NIC with that name, renaming the second
  interface with this name will always fail.

  While Debian still carries a patch called "Revert-udev-network-device-
  renaming-immediately-give.patch"[4] that tries to keep support of
  already deprecated "75-persistent-net-generator.rules" based interface
  renaming mechanism, this patch also propagated into Ubuntu[5]. This
  patch will retry renaming with a 90 seconds timeout when the error
  code is -EEXIST, so the uevent processing will always be blocked in
  the last ifrename step in the victim system.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: udev 237-3ubuntu10.24 [modified: lib/udev/rules.d/50-firmware.rules lib/udev/rules.d/50-udev-default.rules lib/udev/rules.d/73-special-net-names.rules lib/udev/rules.d/73-usb-net-by-mac.rules]
  ProcVersionSignature: Ubuntu 4.15.0-1043.48-oem 4.15.18
  Uname: Linux 4.15.0-1043-oem x86_64
  ApportVersion: 2.20.9-0ubuntu7.2
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  CustomUdevRuleFiles: 70-snap.core.rules 95-oem-hotkey-osd.rules
  Date: Wed Jul 24 15:30:59 2019
  DistributionChannelDescriptor:
   # This is the distribution channel descriptor for the OEM CDs
   # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
   canonical-oem-somerville-bionic-amd64-20180608-47+beaver-jorah+X90
  InstallationDate: Installed on 2019-07-03 (20 days ago)
  InstallationMedia: Ubuntu 18.04 "Bionic" - Build amd64 LIVE Binary 20180608-09:38
  MachineType: Dell Inc. Latitude 7424 Rugged Extreme
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-1043-oem.efi.signed root=UUID=5da90c85-3500-49a2-b989-71a604f9eec4 ro mem_sleep_default=deep quiet splash systemd.log_level=debug udev.log-priority=debug log_buf_len=8M vt.handoff=1
  SourcePackage: systemd
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 05/27/2019
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: 1.5.0
  dmi.board.name: 0Y7FK3
  dmi.board.vendor: Dell Inc.
  dmi.board.version: X03
  dmi.chassis.type: 10
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvr1.5.0:bd05/27/2019:svnDellInc.:pnLatitude7424RuggedExtreme:pvr:rvnDellInc.:rn0Y7FK3:rvrX03:cvnDellInc.:ct10:cvr:
  dmi.product.family: Latitude
  dmi.product.name: Latitude 7424 Rugged Extreme
  dmi.sys.vendor: Dell Inc.

  [1]: https://www.dell.com/support/article/tw/zh/twdhs1/sln301147/what-is-mac-address-pass-through?lang=en
  [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/usb/r8152.c
  [3]: https://salsa.debian.org/systemd-team/systemd/blob/master/debian/extra/rules/73-usb-net-by-mac.rules
  [4]: https://salsa.debian.org/systemd-team/systemd/blob/master/debian/patches/debian/Revert-udev-network-device-renaming-immediately-give.patch
  [5]: https://git.launchpad.net/~ubuntu-core-dev/ubuntu/+source/systemd/tree/debian/patches/debian/Revert-udev-network-device-renaming-immediately-give.patch?h=ubuntu-bionic

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