selftests/bpf: Add more test cases for LPM trie

JIRA: https://issues.redhat.com/browse/RHEL-85485

commit 04d4ce9
Author: Hou Tao <[email protected]>
Date:   Fri Dec 6 19:06:22 2024 +0800

    selftests/bpf: Add more test cases for LPM trie

    Add more test cases for LPM trie in test_maps:

    1) test_lpm_trie_update_flags
    It constructs various use cases for BPF_EXIST and BPF_NOEXIST and check
    whether the return value of update operation is expected.

    2) test_lpm_trie_update_full_maps
    It tests the update operations on a full LPM trie map. Adding new node
    will fail and overwriting the value of existed node will succeed.

    3) test_lpm_trie_iterate_strs and test_lpm_trie_iterate_ints
    There two test cases test whether the iteration through get_next_key is
    sorted and expected. These two test cases delete the minimal key after
    each iteration and check whether next iteration returns the second
    minimal key. The only difference between these two test cases is the
    former one saves strings in the LPM trie and the latter saves integers.
    Without the fix of get_next_key, these two cases will fail as shown
    below:
      test_lpm_trie_iterate_strs(1091):FAIL:iterate #2 got abc exp abS
      test_lpm_trie_iterate_ints(1142):FAIL:iterate #1 got 0x2 exp 0x1

    Signed-off-by: Hou Tao <[email protected]>
    Link: https://lore.kernel.org/r/[email protected]
    Signed-off-by: Alexei Starovoitov <[email protected]>

Signed-off-by: Viktor Malik <[email protected]>

Author: viktormalik