Merge branch 'bpf-fix-backward-progress-bug-in-bpf_iter_udp'

Martin KaFai Lau says:

====================
bpf: Fix backward progress bug in bpf_iter_udp

From: Martin KaFai Lau <martin.lau@kernel.org>

This patch set fixes an issue in bpf_iter_udp that makes backward
progress and prevents the user space process from finishing. There is
a test at the end to reproduce the bug.

Please see individual patches for details.

v3:
- Fixed the iter_fd check and local_port check in the
  patch 3 selftest. (Yonghong)
- Moved jhash2 to test_jhash.h in the patch 3. (Yonghong)
- Added explanation in the bucket selection in the patch 3. (Yonghong)

v2:
- Added patch 1 to fix another bug that goes back to
  the previous bucket
- Simplify the fix in patch 2 to always reset iter->offset to 0
- Add a test case to close all udp_sk in a bucket while
  in the middle of the iteration.
====================

Link: https://lore.kernel.org/r/20240112190530.3751661-1-martin.lau@linux.dev


Signed-off-by: Alexei Starovoitov <ast@kernel.org>