selftests/bpf: Assert link info uprobe_multi count & path_size if unset

Add assertions in `bpf_link_info.uprobe_multi` test to verify that
`count` and `path_size` fields are correctly populated when the fields
are unset.

This tests a previous bug where the `path_size` field was not populated
when `path` and `path_size` were unset.

Signed-off-by: Tyrone Wu <wudevelops@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241011000803.681190-2-wudevelops@gmail.com

diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
index 745c5ada4c4bfd74d8c4f18a1277981fa3b9d221..d50cbd8040d45fdb51cef51d087f3c8813926a1e 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
+++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
@@ -420,6 +420,15 @@ verify_umulti_link_info(int fd, bool retprobe, __u64 *offsets,
        if (!ASSERT_NEQ(err, -1, "readlink"))
                return -1;
 
+       memset(&info, 0, sizeof(info));
+       err = bpf_link_get_info_by_fd(fd, &info, &len);
+       if (!ASSERT_OK(err, "bpf_link_get_info_by_fd"))
+               return -1;
+
+       ASSERT_EQ(info.uprobe_multi.count, 3, "info.uprobe_multi.count");
+       ASSERT_EQ(info.uprobe_multi.path_size, strlen(path) + 1,
+                 "info.uprobe_multi.path_size");
+
        for (bit = 0; bit < 8; bit++) {
                memset(&info, 0, sizeof(info));
                info.uprobe_multi.path = ptr_to_u64(path_buf);