netdev - Re: [PATCH bpf-next v2 06/14] bpf: net_sched: Add basic bpf qdisc kfuncs

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Message-ID: <CAMB2axM1qA-+4PYyYJ3AmoKHoKAWwu-8sh1UYdZBsPGURbmh4Q@mail.gmail.com>
Date: Fri, 10 Jan 2025 10:00:47 -0800
From: Amery Hung <ameryhung@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org, daniel@...earbox.net, 
	andrii@...nel.org, alexei.starovoitov@...il.com, martin.lau@...nel.org, 
	sinquersw@...il.com, toke@...hat.com, jhs@...atatu.com, jiri@...nulli.us, 
	stfomichev@...il.com, ekarani.silvestre@....ufcg.edu.br, 
	yangpeihao@...u.edu.cn, xiyou.wangcong@...il.com, yepeilin.cs@...il.com
Subject: Re: [PATCH bpf-next v2 06/14] bpf: net_sched: Add basic bpf qdisc kfuncs

On Thu, Jan 9, 2025 at 4:24 PM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>
> On 12/20/24 11:55 AM, Amery Hung wrote:
> > +BTF_KFUNCS_START(qdisc_kfunc_ids)
> > +BTF_ID_FLAGS(func, bpf_skb_get_hash, KF_TRUSTED_ARGS)
> > +BTF_ID_FLAGS(func, bpf_kfree_skb, KF_RELEASE)
> > +BTF_ID_FLAGS(func, bpf_qdisc_skb_drop, KF_RELEASE)
> > +BTF_ID_FLAGS(func, bpf_dynptr_from_skb, KF_TRUSTED_ARGS)
> > +BTF_KFUNCS_END(qdisc_kfunc_ids)
> > +
> > +BTF_SET_START(qdisc_common_kfunc_set)
> > +BTF_ID(func, bpf_skb_get_hash)
> > +BTF_ID(func, bpf_kfree_skb)
>
> I think bpf_dynptr_from_skb should also be here.

Good catch

>
> > +BTF_SET_END(qdisc_common_kfunc_set)
> > +
> > +BTF_SET_START(qdisc_enqueue_kfunc_set)
> > +BTF_ID(func, bpf_qdisc_skb_drop)
> > +BTF_SET_END(qdisc_enqueue_kfunc_set)
> > +
> > +static int bpf_qdisc_kfunc_filter(const struct bpf_prog *prog, u32 kfunc_id)
> > +{
> > +     if (bpf_Qdisc_ops.type != btf_type_by_id(prog->aux->attach_btf,
> > +                                              prog->aux->attach_btf_id))
> > +             return 0;
> > +
> > +     /* Skip the check when prog->attach_func_name is not yet available
> > +      * during check_cfg().
>
> Instead of using attach_func_name, it is better to directly use the
> prog->expected_attach_type provided by the user space. It is essentially the
> member index of the "struct Qdisc_ops". Take a look at the prog_ops_moff() in
> bpf_tcp_ca.c.

I will replace all places that use attach_func_name to refer to the
ops to prog_ops_moff.

Thank,
Amery

>
> > +      */
> > +     if (!btf_id_set8_contains(&qdisc_kfunc_ids, kfunc_id) ||
> > +         !prog->aux->attach_func_name)
> > +             return 0;
> > +
> > +     if (!strcmp(prog->aux->attach_func_name, "enqueue")) {
> > +             if (btf_id_set_contains(&qdisc_enqueue_kfunc_set, kfunc_id))
> > +                    return 0;
> > +     }
> > +
> > +     return btf_id_set_contains(&qdisc_common_kfunc_set, kfunc_id) ? 0 : -EACCES;
> > +}