Remove net.ipv4.tcp_max_syn_backlog from sysctl whitelist

[sttts]

Remove net.ipv4.tcp_max_syn_backlog from sysctl whitelist. This is not namespaced in today's kernels, but must be set on node-level.

Having this on the whitelist, wouldn't harm because the kernel only offers namespaced net.* sysctls in the /proc/sys tree. But having a sysctl on the whitelist, which cannot be used, doesn't make sense either.

1.4 justification:

• Risk: the whitelist is a published API. We shouldn't have sysctls on there which do not work.
• Rollback: nothing should depend on this behavior.
• Cost: the cost of this is relatively low, as no pod with this sysctl will launch.

---

This change is

[k8s-bot]

GCE e2e build/test passed for commit 9a34eee.

• Test Results
• Build Log
• Test Artifacts
• Internal Jenkins Results

[vishh]

LGTM

[k8s-github-robot]

@k8s-bot test this [submit-queue is verifying that this PR is safe to merge]

[k8s-github-robot]

@k8s-bot test this issue: #IGNORE

Tests have been pending for 24 hours

[k8s-bot]

GCE e2e build/test passed for commit 9a34eee.

• Test Results
• Build Log
• Test Artifacts
• Internal Jenkins Results

[k8s-github-robot]

Automatic merge from submit-queue

[discordianfish]

@sttts Either this has changed or you mixed it up with net.core.netdev_max_backlog:

$ S=net.ipv4.tcp_max_syn_backlog; docker run -ti --rm --sysctl "$S"=12345 ubuntu sysctl "$S"; docker run -ti --rm ubuntu sysctl "$S"
net.ipv4.tcp_max_syn_backlog = 12345
net.ipv4.tcp_max_syn_backlog = 128
S=net.core.netdev_max_backlog; docker run -ti --rm --sysctl "$S"=12345 ubuntu sysctl "$S"; docker run -ti --rm ubuntu sysctl "$S"
docker: Error response from daemon: OCI runtime create failed: container_linux.go:349: starting container process caused "process_linux.go:449: container init caused \"write sysctl key net.core.netdev_max_backlog: open /proc/sys/net/core/netdev_max_backlog: no such file or directory\"": unknown.
ERRO[0000] error waiting for container: context canceled
sysctl: cannot stat /proc/sys/net/core/netdev_max_backlog: No such file or directory