Re: [PATCH bpf-next v2 2/2] bpf: Introduce bpf user log

[Alexei Starovoitov]

On Fri, Jul 7, 2023 at 9:08 PM Leon Hwang <hffilwlqm@xxxxxxxxx> wrote:
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 34fa334938ba5..8a458cfcd91bd 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1549,7 +1549,6 @@ union bpf_attr {
>                 };
>                 __u32           attach_type;    /* attach type */
>                 __u32           flags;          /* extra flags */
> -               struct bpf_generic_user_log log; /* user log */
>                 union {
>                         __u32           target_btf_id;  /* btf_id of target to attach to */
>                         struct {
> @@ -1585,6 +1584,9 @@ union bpf_attr {
>                                 __s32           priority;
>                                 __u32           flags;
>                         } netfilter;
> +                       struct {
> +                               struct bpf_generic_user_log ulog; /* user log */
> +                       } xdp;

1.
You cannot break api in patch 1 and fix it in patch 2.

2.
libbpf side is missing.

3.
selftest is missing.

4.
bpf_vlog_finalize() should be used and error propagated back through
link_create.
Same api must be used: log_level, log_size, log_buf, log_true_size.

But considering all that I agree with Daniel Xu that
tracepoint would be better here.