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Bug 2027908

Summary: Network interface names are not necessarily predictable and don't match previous names
Product: Red Hat Enterprise Linux 8 Reporter: Shannon Nelson <snelson>
Component: systemdAssignee: systemd-maint
Status: CLOSED ERRATA QA Contact: Frantisek Sumsal <fsumsal>
Severity: urgent Docs Contact:
Priority: urgent    
Version: 8.5CC: dornelas, dtardon, fkrska, jamacku, mmatsuya, msekleta, sbroz, sferguso, systemd-maint-list
Target Milestone: rcKeywords: Regression, Triaged, ZStream
Target Release: ---Flags: pm-rhel: mirror+
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: systemd-239-58.el8 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 2030027 (view as bug list) Environment:
Last Closed: 2022-05-10 15:25:48 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2005008, 2022432    
Bug Blocks: 2030027    

Description Shannon Nelson 2021-12-01 02:54:29 UTC
A past problem had udev generating incorrect names (bz1827462), but that
seems to be fixed.  This is a different problem.

When booting up an HPE:ProLiant DL360 Gen10 running RHEL 8.5 with kernel
4.18.0-348.2.1.el8_5.x86_64 that has our Pensando DSC NIC, using the
ionic driver, we would expect to see names such as enp57s0 and enp58s0
for these interfaces.  However, we see devices named ens2 and eth0.  If
we unload the ionic driver and reload it, we now see interfaces eth1 and eth2.

Hence, names we didn't expect, and not predictable.

In the messages log we see entries like this:
Nov 29 12:39:27 sln-dev systemd-udevd[1273]: Using default interface naming scheme 'rhel-8.0'.
Nov 29 12:39:27 sln-dev systemd-udevd[1273]: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Nov 29 12:39:27 sln-dev systemd-udevd[1273]: Could not set AlternativeName= or apply AlternativeNamesPolicy= on ens2: File exists
Nov 29 12:39:27 sln-dev systemd-udevd[1273]: Could not apply link config to ens2, ignoring: File exists
Nov 29 12:39:27 sln-dev systemd-udevd[1273]: Error changing net interface name 'ens2' to 'enp57s0': File exists
Nov 29 12:39:27 sln-dev systemd-udevd[1273]: could not rename interface '8' from 'ens2' to 'enp57s0': File exists

After some experimentation with unloading and loading the driver, I found that simply
commenting out the AlternativeNamesPolicy line in /usr/lib/systemd/network/99-default.link
was a way to stop these errors and to get the expected interface names.  I also had to
rebuild the initramfs since it also has this configuration and does the initial interface
setup at boot time.

udev info with AlternativeNamesPolicy:

# udevadm info /sys/class/net/eth0   
P: /devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/net/eth0
E: DEVPATH=/devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/net/eth0
E: ID_BUS=pci
E: ID_MODEL_FROM_DATABASE=DSC Ethernet Controller (Naples 25Gb 2-port SFP28 x8 4GB)
E: ID_MODEL_ID=0x1002
E: ID_NET_DRIVER=ionic
E: ID_NET_LINK_FILE=/usr/lib/systemd/network/99-default.link
E: ID_NET_NAME_MAC=enx00aecd05bd40
E: ID_NET_NAME_PATH=enp57s0
E: ID_NET_NAME_SLOT=ens2
E: ID_NET_NAMING_SCHEME=rhel-8.0
E: ID_OUI_FROM_DATABASE=Pensando Systems
E: ID_PATH=pci-0000:39:00.0
E: ID_PATH_TAG=pci-0000_39_00_0
E: ID_PCI_CLASS_FROM_DATABASE=Network controller
E: ID_PCI_SUBCLASS_FROM_DATABASE=Ethernet controller
E: ID_VENDOR_FROM_DATABASE=Pensando Systems
E: ID_VENDOR_ID=0x1dd8
E: IFINDEX=8
E: INTERFACE=eth0
E: SUBSYSTEM=net
E: SYSTEMD_ALIAS=/sys/subsystem/net/devices/enp57s0
E: TAGS=:systemd:
E: USEC_INITIALIZED=4642629

udev info with no AlternativeNamesPolicy:

# udevadm info /sys/class/net/enp57s0
P: /devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/net/enp57s0
E: DEVPATH=/devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/net/enp57s0
E: ID_BUS=pci
E: ID_MODEL_FROM_DATABASE=DSC Ethernet Controller (Naples 25Gb 2-port SFP28 x8 4GB)
E: ID_MODEL_ID=0x1002
E: ID_NET_DRIVER=ionic
E: ID_NET_LINK_FILE=/usr/lib/systemd/network/99-default.link
E: ID_NET_NAME=ens2
E: ID_NET_NAME_MAC=enx00aecd05bd40
E: ID_NET_NAME_PATH=enp57s0
E: ID_NET_NAME_SLOT=ens2
E: ID_NET_NAMING_SCHEME=rhel-8.0
E: ID_OUI_FROM_DATABASE=Pensando Systems
E: ID_PATH=pci-0000:39:00.0
E: ID_PATH_TAG=pci-0000_39_00_0
E: ID_PCI_CLASS_FROM_DATABASE=Network controller
E: ID_PCI_SUBCLASS_FROM_DATABASE=Ethernet controller
E: ID_VENDOR_FROM_DATABASE=Pensando Systems
E: ID_VENDOR_ID=0x1dd8
E: IFINDEX=8
E: INTERFACE=enp57s0
E: SUBSYSTEM=net
E: SYSTEMD_ALIAS=/sys/subsystem/net/devices/enp57s0 /sys/subsystem/net/devices/enp57s0
E: TAGS=:systemd:
E: USEC_INITIALIZED=5293134

Comment 1 David Tardon 2021-12-02 16:24:02 UTC
Indeed. I didn't realize the consequences of bug 2022432. We'll have to move the new name assignment before alt. names handling if it is not fixed.

(In any case, that the new name is assigned as the very last step in link_config_apply() seems unnecessarily fragile to me. IMHO setting of ID_NET_NAME= should not depend upon successful setting of link properties and whatnot.)

Comment 12 errata-xmlrpc 2022-05-10 15:25:48 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (systemd bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:2069