From: Matt Bobrowski <mattbobrowski@google.com>
To: Tejun Heo <tj@kernel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
ohn Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>,
Jiri Olsa <jolsa@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Chuyi Zhou <zhouchuyi@bytedance.com>
Subject: Re: [PATCH bpf-next 1/2] bpf: add new BPF_CGROUP_ITER_CHILDREN_ONLY control option
Date: Mon, 26 Jan 2026 09:14:12 +0000 [thread overview]
Message-ID: <aXcwZOGHTdAIbzrP@google.com> (raw)
In-Reply-To: <aXPC_KMX_rvO14lR@slm.duckdns.org>
On Fri, Jan 23, 2026 at 08:50:36AM -1000, Tejun Heo wrote:
> Hello,
>
> On Fri, Jan 23, 2026 at 11:06:21AM +0000, Matt Bobrowski wrote:
> > Would your stance change if Tejun agreed to mark css_next_child() as
> > exportable, or simply agreed to it being used from BPF cgroup
> > iterators?
>
> FWIW, I don't think there's any issue to exposing css_next_child(). This is
> a part of the fundamental structure of cgroups and I don't see it changing
> in any foreseeable future.
Thanks for weighing in on this Tejun.
> That said, I wonder whether it'd be more flexible to expose
> css_rightmost_descendant() which allows skipping the current subtree
> during pre-order traversals. However, this has higher complexity for
> traversing just immediate children as it would have to skip each
> child subtree.
Yeah, css_rightmost_descendant() isn't what I'm immediately after at
this point. However, I also wouldn't argue against exposing it as
another possible control order available to the BPF cgroup iterators.
prev parent reply other threads:[~2026-01-26 9:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-21 13:54 [PATCH bpf-next 1/2] bpf: add new BPF_CGROUP_ITER_CHILDREN_ONLY control option Matt Bobrowski
2026-01-21 13:54 ` [PATCH bpf-next 2/2] bpf/selftests: cover " Matt Bobrowski
2026-01-21 19:14 ` [PATCH bpf-next 1/2] bpf: add new " Song Liu
2026-01-22 12:31 ` Matt Bobrowski
2026-01-23 4:26 ` Alexei Starovoitov
2026-01-23 11:06 ` Matt Bobrowski
2026-01-23 17:17 ` Alexei Starovoitov
2026-01-26 9:03 ` Matt Bobrowski
2026-01-27 2:26 ` Alexei Starovoitov
2026-01-27 8:28 ` Matt Bobrowski
2026-01-23 18:50 ` Tejun Heo
2026-01-26 9:14 ` Matt Bobrowski [this message]
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