From: bot+bpf-ci@kernel.org
To: mahe.tardy@gmail.com,bpf@vger.kernel.org
Cc: qmo@kernel.org,ast@kernel.org,daniel@iogearbox.net,andrii@kernel.org,eddyz87@gmail.com,memxor@gmail.com,martin.lau@linux.dev,song@kernel.org,yonghong.song@linux.dev,jolsa@kernel.org,emil@etsalapatis.com,ihor.solodrai@linux.dev,shuah@kernel.org,mahe.tardy@gmail.com,hi@tychen.cc,gyutae.bae@navercorp.com,sh_def@163.com,josef@toxicpanda.com,linux-kernel@vger.kernel.org,linux-kselftest@vger.kernel.org,ast@kernel.org,andrii@kernel.org,daniel@iogearbox.net,martin.lau@kernel.org,eddyz87@gmail.com,yonghong.song@linux.dev,mason@kernel.org,ihor.solodrai@linux.dev
Subject: Re: [PATCH bpf-next v3 1/5] libbpf: Count entry programs for bpf_gen__init()
Date: Mon, 2 Nov 2026 20:45:57 +0000 (UTC) [thread overview]
Message-ID: <c013a7069c06d1120f89eb75e9418938b9e4e71cc81043f41f11cb06d75ca634@mail.kernel.org> (raw)
In-Reply-To: <20261102201356.5798-2-mahe.tardy@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2467 bytes --]
> libbpf: Count entry programs for bpf_gen__init()
TL;DR: Nit only: the comment in bpf_gen__init() in gen_loader.c still says
nr_progs includes subprogs, which is now stale after this change. Suggests
updating it.
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
[ ... ]
> @@ -9815,13 +9815,16 @@ static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const ch
> if (prog_is_subprog(obj, &obj->programs[i]) &&
> prog_has_callx(&obj->programs[i]))
> text_has_callx = true;
> - for (i = 0; i < obj->nr_programs; i++)
> + for (i = 0; i < obj->nr_programs; i++) {
> + if (prog_is_subprog(obj, &obj->programs[i]))
> + continue;
> + nr_obj_progs++;
> if (obj->programs[i].load_strategy != BPF_PROG_LOAD_STRATEGY_DISABLED &&
> - !prog_is_subprog(obj, &obj->programs[i]) &&
> (text_has_callx || prog_has_callx(&obj->programs[i])))
> nr_progs++;
> + }
> bpf_gen__init(obj->gen_loader, obj->log_level | extra_log_level,
> - obj->nr_programs, obj->nr_maps, nr_func_ptr_maps * nr_progs);
> + nr_obj_progs, obj->nr_maps, nr_func_ptr_maps * nr_progs);
This isn't a bug, but the comment in bpf_gen__init() now looks stale:
tools/lib/bpf/gen_loader.c:bpf_gen__init() {
...
/* nr_progs includes subprogs and progs that are not loaded */
nr_progs = min(nr_progs, MAX_USED_PROGS);
...
}
With this change, the nr_progs argument no longer includes subprogs. It is
the number of entry programs, which is the same count that
bpf_object__for_each_program() and the skeleton expose, and it still
includes entry programs that are not loaded. The comment came from
259172bb6514 ("libbpf: Fix gen_loader assumption on number of programs."),
which the commit message cites.
None of the later patches in the series (276212ecac70, 28aa06d2c9ca,
c9412c70e104, 5b9c2e5eed2a) update it. 276212ecac70 ("libbpf: Track
generated loader link FDs") also sizes link_fds from this same nr_progs
value, so the comment now misdescribes a value that later code depends on.
Should the comment be changed to something like "nr_progs includes progs
that are not loaded, but not subprogs"?
---
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/41519963115
next prev parent reply other threads:[~2026-11-02 20:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 20:13 [PATCH bpf-next v3 0/5] libbpf: Support gen loader attach Mahe Tardy
2026-11-02 20:13 ` [PATCH bpf-next v3 1/5] libbpf: Count entry programs for bpf_gen__init() Mahe Tardy
2026-11-02 20:45 ` bot+bpf-ci [this message]
2026-11-02 20:13 ` [PATCH bpf-next v3 2/5] libbpf: Track generated loader link FDs Mahe Tardy
2026-11-02 20:13 ` [PATCH bpf-next v3 3/5] libbpf: Emit BPF_LINK_CREATE calls in generated loaders Mahe Tardy
2026-11-02 20:13 ` [PATCH bpf-next v3 4/5] bpftool: Add attach option for light skeleton generation Mahe Tardy
2026-11-02 20:56 ` bot+bpf-ci
2026-11-02 20:13 ` [PATCH bpf-next v3 5/5] selftests/bpf: Test gen loader attach Mahe Tardy
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