netdev - Re: [PATCH bpf-next v2 15/16] bpf: Realign skb metadata for TC progs using data

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Message-ID: <87qzs2imh3.fsf@cloudflare.com>
Date: Tue, 06 Jan 2026 20:12:56 +0100
From: Jakub Sitnicki <jakub@...udflare.com>
To: Amery Hung <ameryhung@...il.com>, Alexei Starovoitov
 <alexei.starovoitov@...il.com>,  Martin KaFai Lau <martin.lau@...ux.dev>
Cc: Martin KaFai Lau <martin.lau@...nel.org>,  bpf <bpf@...r.kernel.org>,
  Network Development <netdev@...r.kernel.org>,  "David S. Miller"
 <davem@...emloft.net>,  Eric Dumazet <edumazet@...gle.com>,  Jakub
 Kicinski <kuba@...nel.org>,  Paolo Abeni <pabeni@...hat.com>,  Alexei
 Starovoitov <ast@...nel.org>,  Daniel Borkmann <daniel@...earbox.net>,
  Jesper Dangaard Brouer <hawk@...nel.org>,  John Fastabend
 <john.fastabend@...il.com>,  Stanislav Fomichev <sdf@...ichev.me>,  Simon
 Horman <horms@...nel.org>,  Andrii Nakryiko <andrii@...nel.org>,  Eduard
 Zingerman <eddyz87@...il.com>,  Song Liu <song@...nel.org>,  Yonghong Song
 <yonghong.song@...ux.dev>,  KP Singh <kpsingh@...nel.org>,  Hao Luo
 <haoluo@...gle.com>,  Jiri Olsa <jolsa@...nel.org>,  kernel-team
 <kernel-team@...udflare.com>
Subject: Re: [PATCH bpf-next v2 15/16] bpf: Realign skb metadata for TC
 progs using data_meta

On Tue, Jan 06, 2026 at 09:46 AM -08, Amery Hung wrote:
> On Tue, Jan 6, 2026 at 9:36 AM Jakub Sitnicki <jakub@...udflare.com> wrote:
>> --- a/kernel/bpf/verifier.c
>> +++ b/kernel/bpf/verifier.c
>> @@ -21806,6 +21806,14 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
>>                         env->prog = new_prog;
>>                         delta += cnt - 1;
>>
>> +                       /* gen_prologue emits function calls with target address
>> +                        * relative to __bpf_call_base. Skip patch_call_imm fixup.
>> +                        */
>> +                       for (i = 0; i < cnt - 1; i++) {
>> +                               if (bpf_helper_call(&env->prog->insnsi[i]))
>> +                                       env->insn_aux_data[i].finalized_call = true;
>> +                       }
>> +
>>                         ret = add_kfunc_in_insns(env, insn_buf, cnt - 1);
>
> And then we can get rid of this function as there is no use case for
> having a new kfunc in gen_{pro,epi}logue.

Happy to convert bpf_{qdisc,testmod} gen_{pro,epi}logue to use
BPF_EMIT_CALL instead of BPF_CALL_KFUNC.

If it's alright with you, I'd like to kill kfunc support in
{pro,epi}logue as a follow up.

Looks like there will be a bit of churn in selftests to remove the
coverage. And this series is getting quite long.