> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 0c8bf0b5c..70a00da54 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
[ ... ]
> @@ -13503,7 +13510,9 @@ struct bpf_link *bpf_map__attach_struct_ops(const
> struct bpf_map *map)
> return &link->link;
> }
>
> - fd = bpf_link_create(map->fd, 0, BPF_STRUCT_OPS, NULL);
> + link_opts.cgroup.relative_fd = OPTS_GET(opts, relative_fd, 0);
> +
> + fd = bpf_link_create(map->fd, 0, BPF_STRUCT_OPS, &link_opts);
The expected_revision field from bpf_struct_ops_opts is defined in the public
API but doesn't appear to be forwarded here. bpf_link_create() reads
opts->cgroup.expected_revision for BPF_STRUCT_OPS, and similar functions like
bpf_program__attach_cgroup_opts() forward all fields including
expected_revision.
Was the expected_revision field intentionally left unused, or should there be a
line here like:
link_opts.cgroup.expected_revision = OPTS_GET(opts, expected_revision, 0);
Note: A later commit in this series (e83943e72 "libbpf: Support passing
user-defined flags for struct_ops") adds forwarding for the flags field, but
expected_revision remains unused through the end of the series.
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index dfc37a615..5aef44bcf 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -920,6 +920,20 @@ bpf_program__attach_cgroup_opts(const struct bpf_program
> *prog, int cgroup_fd,
> struct bpf_map;
>
> LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map
> *map);
> +
> +struct bpf_struct_ops_opts {
> + /* size of this struct, for forward/backward compatibility */
> + size_t sz;
> + __u32 flags;
> + __u32 relative_fd;
> + __u64 expected_revision;
^^^^^^^^^^^^^^^^^
The expected_revision field is defined here but is not read by
bpf_map__attach_struct_ops_opts() in libbpf.c, so any value set by users
will be silently ignored.
> + size_t :0;
> +};
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21665371660
AI-authorship-score: low
AI-authorship-explanation: The commit follows standard libbpf API extension
patterns with consistent naming and structure typical of experienced kernel
developers.
issues-found: 1
issue-severity-score: low
issue-severity-explanation: The expected_revision field in the public API
struct is silently ignored, which could confuse users but does not cause system
instability or crashes.
