** Description changed: + [impact] + + On Dell system with BIOS-based "MAC passthrough", there can be multiple + USB nics with identical MAC addresses. Since the udev rules in Debian + and Ubuntu assign interface names for USB nics by mac address (because + that is the only consistent identifier for USB nics; their path can + change based on which USB port they are connected to), it's impossible + to name two interfaces with the same name. As Ubuntu also carries a + patch to retry renaming of any interface when the first renaming fails, + this causes a 90 second delay before being able to the "MAC passthrough" + nic after connecting it. + + [test case] + + On a system with this "MAC passthrough" enabled and required devices, + boot the system and then connect to the dock or connect the second USB + nic with identical MAC. It will not be usable for 90 seconds as its + renames takes that long to timeout. + + [regression potential] + + the change here is very limited to only Dell systems with the specific + USB vendor/product ID affected by this, and additionally the change only + sets a ENV flag in the udev rule, which is later used by udevd to skip + the rename-retries for 90 seconds. So, the regression potential for + anyone else without a system affected by this "MAC passthrough" should + be very low, and any regression potential for those with this "MAC + passthrough" should still be low, as this only skips the rename-retry + that we know will never succeed. + + However, the regression potential is likely limited to failure to + properly name a USB nic, or other bugs during the udev processing of new + USB nics. + + [other info] + + original description: + --- + + This is a bug reopen from https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1837700 The original one caused systemd regressed. https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1842651 This issue needs an alternative solution. -------------------------------------------------------------------------------- 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 + # 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
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1843381 Title: Dell system takes a long time to connect network with external dock To manage notifications about this bug go to: https://bugs.launchpad.net/oem-priority/+bug/1843381/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
