On Tue, Oct 4, 2022 at 4:12 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>
> Extend libbpf attach opts and add a new detach opts API so this can be used
> to add/remove fd-based tc BPF programs. For concrete usage examples, see the
> extensive selftests that have been developed as part of this series.
>
> Co-developed-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
> Signed-off-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> ---
> tools/lib/bpf/bpf.c | 21 +++++++++++++++++++++
> tools/lib/bpf/bpf.h | 17 +++++++++++++++--
> tools/lib/bpf/libbpf.map | 1 +
> 3 files changed, 37 insertions(+), 2 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 18b1e91cc469..d1e338ac9a62 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -670,6 +670,27 @@ int bpf_prog_detach2(int prog_fd, int target_fd, enum bpf_attach_type type)
> return libbpf_err_errno(ret);
> }
>
> +int bpf_prog_detach_opts(int prog_fd, int target_fd,
> + enum bpf_attach_type type,
> + const struct bpf_prog_detach_opts *opts)
> +{
> + const size_t attr_sz = offsetofend(union bpf_attr, replace_bpf_fd);
> + union bpf_attr attr;
> + int ret;
> +
> + if (!OPTS_VALID(opts, bpf_prog_detach_opts))
> + return libbpf_err(-EINVAL);
> +
> + memset(&attr, 0, attr_sz);
> + attr.target_fd = target_fd;
> + attr.attach_bpf_fd = prog_fd;
> + attr.attach_type = type;
> + attr.attach_priority = OPTS_GET(opts, attach_priority, 0);
> +
> + ret = sys_bpf(BPF_PROG_DETACH, &attr, attr_sz);
> + return libbpf_err_errno(ret);
> +}
> +
> int bpf_link_create(int prog_fd, int target_fd,
> enum bpf_attach_type attach_type,
> const struct bpf_link_create_opts *opts)
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index bef7a5282188..96de58fecdbc 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -286,8 +286,11 @@ LIBBPF_API int bpf_obj_get_opts(const char *pathname,
>
> struct bpf_prog_attach_opts {
> size_t sz; /* size of this struct for forward/backward compatibility */
> - unsigned int flags;
> - int replace_prog_fd;
> + __u32 flags;
> + union {
> + int replace_prog_fd;
> + __u32 attach_priority;
> + };
just add a new field, unions are very confusing in API structures.
It's ok if some unused fields stay zero.
> };
> #define bpf_prog_attach_opts__last_field replace_prog_fd
>
> @@ -296,9 +299,19 @@ LIBBPF_API int bpf_prog_attach(int prog_fd, int attachable_fd,
> LIBBPF_API int bpf_prog_attach_opts(int prog_fd, int attachable_fd,
> enum bpf_attach_type type,
> const struct bpf_prog_attach_opts *opts);
> +
> +struct bpf_prog_detach_opts {
> + size_t sz; /* size of this struct for forward/backward compatibility */
> + __u32 attach_priority;
please add size_t: 0; at the end to ensure better zero-initialization
by compiler
> +};
> +#define bpf_prog_detach_opts__last_field attach_priority
> +
> LIBBPF_API int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);
> LIBBPF_API int bpf_prog_detach2(int prog_fd, int attachable_fd,
> enum bpf_attach_type type);
> +LIBBPF_API int bpf_prog_detach_opts(int prog_fd, int target_fd,
> + enum bpf_attach_type type,
given we add detach_opts API, is type something that always makes
sense? If not, let's move it into opts.
> + const struct bpf_prog_detach_opts *opts);
>
> union bpf_iter_link_info; /* defined in up-to-date linux/bpf.h */
> struct bpf_link_create_opts {
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index c1d6aa7c82b6..0c94b4862ebb 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -377,4 +377,5 @@ LIBBPF_1.1.0 {
> user_ring_buffer__reserve;
> user_ring_buffer__reserve_blocking;
> user_ring_buffer__submit;
> + bpf_prog_detach_opts;
let's keep this sorted
> } LIBBPF_1.0.0;
> --
> 2.34.1
>
