net:fib_rule_tests.sh in ubuntu_kselftests_net fails on Noble

[Masahiro Yamada]

In our SRU cycles, all Noble kernels fail in the aforementioned kselftests:

      11238 20:50:51 DEBUG| [stdout] # Cannot open network namespace "testns": No such file or directory

This error is caused by the local fix added in 2019:
"UBUNTU: SAUCE: selftests: net: fix "from" match test in fib_rule_tests.sh"

It was no longer necessary because a similar fix was applied in upstream:
d1abf388604f ("selftests: fib_rule_tests: enable forwarding before ipv4 from/iif test")

However, such a Ubuntu-local commit is often blindly carried over to future releases because nobody re-evaluates whether it is still needed or not.

Now, it is causing a real issue on Noble kselftests.

  $ linux/tools/testing/selftests/net$ sudo ./fib_rule_tests.sh
  Cannot open network namespace "testns": No such file or directory

The reason for the failure is obvious; there is no such a namespace since the upstream commit 6c0ee7b4d69d ("selftests/net: convert fib_rule_tests.sh to run it in unique namespace").

Reverting the outdated commit fixes this failure.

[Masahiro Yamada (myamada)]

A patch.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux/6.8.0-38.38 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-noble-linux' to 'verification-done-noble-linux'. If the problem still exists, change the tag 'verification-needed-noble-linux' to 'verification-failed-noble-linux'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!