[Expired for neutron because there has been no activity for 60 days.]
** Changed in: neutron
Status: Incomplete => Expired
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https://bugs.launchpad.net/bugs/1878719
Title:
DHCP Agent's iptables CHECKSUM rule causes skb_warn_bad_offload
kernel
Status in neutron:
Expired
Bug description:
We are hitting this kernel issue due to a DHCP agent CHECKSUM rule
that is probably obsolete/not needed:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1840619
Upgrading the kernel is one workaround, but more disruptive,
especially since still using CentOS7, and kernel fix only made it into
4.19. We should just remove this rule altogether. As per the kernel
issue:
"The changes are limited only to users which have CHECKSUM rules
enabled in their iptables configs. Openstack commonly configures such
rules on deployment, even though they are not necessary, as almost all
packets have their checksum calculated by NICs these days, and
CHECKSUM is only around to service old dhcp clients which would
discard UDP packets with empty checksums.
This commit was selected for upstream -stable 4.18.13, and has made
its way into bionic 4.15.0-58.64 by LP #1836426. There have been no
reported problems and those kernels would have had sufficient testing
with Openstack and its configured iptables rules.
If any users are affected by regression, then they can simply delete
any CHECKSUM entries in their iptables configs."
I can see the metadata agent's CHECKSUM rule was alreayd removed last year:
https://github.com/openstack/neutron/commit/04e995be9898ceaa009344509dc16ca7f589d814
Is there any reason the DHCP agent's was not? Is it safe to just
remove this function and where it is invoked from altogether?
https://github.com/openstack/neutron/blob/master/neutron/agent/linux/dhcp.py#L1739
https://github.com/openstack/neutron/blob/cb55643a0695ebc5b41f50f6edb1546bcc676b71/neutron/agent/linux/dhcp.py#L1691
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