bpf, sockmap: fix issue that residual elements in sockmap cannot be removed · Pull Request !3451 · anolis/cloud-kernel

bugzilla: https://bugzilla.openanolis.cn/show_bug.cgi?id=9456

This PR includes 3 patches:

- #1: Fix the issue of dmesg warning.

- #2: Fix issue that residual elements in sockmap cannot be removed.

We noticed a regression caused by [2], which was merged to linux-5.10.y
since v5.10.80.

After sock_map_unhash() helper was removed in [2], sock elems added to
the bpf sock map via sock_hash_update_common() cannot be removed if they
are in the icsk_accept_queue of the listener sock. Since they have not
been accept()ed, they cannot be removed via sock_map_close()->sock_map_remove_links() either.

It can be reproduced in network test with short-lived connections. If
the server is killed during the test, there is a probability that some
sock elems will remain in the bpf sock map.

And with [1], the sock_map_destroy() helper is introduced to invoke sock_map_remove_links() when inet_csk_listen_stop()->inet_child_forget()->inet_csk_destroy_sock(), to remove the sock elems from the bpf sock map
in such situation.

[1] d8616ee2affc ("bpf, sockmap: Fix sk->sk_forward_alloc warn_on in sk_stream_kill_queues")
(link: https://lore.kernel.org/all/20220524075311.649153-1-wangyufen@huawei.com/)
[2] 8b5c98a67c1b ("bpf, sockmap: Remove unhash handler for BPF sockmap usage")
(link: https://lore.kernel.org/all/20211103204736.248403-3-john.fastabend@gmail.com/)

- #3: Reserve some fields in sk_psock for potential hotfix requirements.

类型	指派人员	状态
审查	dtc maqiao-alibaba Tony Lu David Xuan Zhuo	已完成 (0/0人)
测试	半叶枫尘已测试通过小龙已测试通过	已完成 (2/1人)

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