Expected behaviour:
The kernel should send out a gratuitous ARP on the interface when the following commands are executed:
$ sudo sysctl -w net.ipv4.conf.eth0.arp_notify=1
net.ipv4.conf.eth0.arp_notify = 1
$ sudo ip link set dev eth0 down
$ sudo ip link set dev eth0 up
Result:
The gratuitous ARP packet is generated inside the kernel (inetdev_send_gratuitous_arp() is called) but the packet is never sent out on the interface. Generating gratuitous ARP packets with "arping" works however.
---
ProblemType: Bug
AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access '/dev/snd/': No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.11-0ubuntu27.24
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
CRDA: N/A
CasperMD5CheckResult: skip
DistroRelease: Ubuntu 20.04
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lsusb: Error: command ['lsusb'] failed with exit code 1:
Lsusb-t: Error: command ['lsusb', '-t'] failed with exit code 1: /sys/bus/usb/devices: No such file or directory
Lsusb-v: Error: command ['lsusb', '-v'] failed with exit code 1:
MachineType: QEMU Standard PC (Q35 + ICH9, 2009)
Package: linux (not installed)
PciMultimedia:
ProcEnviron:
TERM=screen
PATH=(custom, no user)
LANG=C.UTF-8
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-1074-kvm root=PARTUUID=88d3c80a-b7b6-4782-8531-3699e254fb95 ro console=tty1 console=ttyS0 panic=-1
ProcVersionSignature: Ubuntu 5.4.0-1074.79-kvm 5.4.195
RelatedPackageVersions:
linux-restricted-modules-5.4.0-1074-kvm N/A
linux-backports-modules-5.4.0-1074-kvm N/A
linux-firmware N/A
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
Tags: focal uec-images
Uname: Linux 5.4.0-1074-kvm x86_64
UnreportableReason: This report is about a package that is not installed.
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: N/A
_MarkForUpload: False
dmi.bios.date: 02/06/2015
dmi.bios.vendor: EFI Development Kit II / OVMF
dmi.bios.version: 0.0.0
dmi.board.name: LXD
dmi.board.vendor: Canonical Ltd.
dmi.board.version: pc-q35-7.0
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-q35-7.0
dmi.modalias: dmi:bvnEFIDevelopmentKitII/OVMF:bvr0.0.0:bd02/06/2015:svnQEMU:pnStandardPC(Q35+ICH9,2009):pvrpc-q35-7.0:rvnCanonicalLtd.:rnLXD:rvrpc-q35-7.0:cvnQEMU:ct1:cvrpc-q35-7.0:
dmi.product.name: Standard PC (Q35 + ICH9, 2009)
dmi.product.version: pc-q35-7.0
dmi.sys.vendor: QEMU
When changing the interface hardware address, it also works: ip link set eth0 addr XX:XX:XX:XX:XX:XX.
It also works when using virtio_net.
It has been tested with e1000e, where it fails when setting the interface up.
When changing the address, __dev_xmit_skb will call sch_direct_xmit and the packet will reach the network. When setting the interface up, __dev_xmit_skb will call dev_qdisc_enqueue and the packet will not reach the network. Interface tx_packets stats will also not change. This indicates a possible issue with the qdisc code when the interface has just been setup. Notice that the code is called from the NETDEV_UP notifier.
Cascardo.