Re: [RFC PATCH bpf-next 8/9] bpf: Introduce cgroup iter

[Hao Luo]

On Mon, May 9, 2022 at 5:18 PM Yosry Ahmed <yosryahmed@xxxxxxxxxx> wrote:
>
> From: Hao Luo <haoluo@xxxxxxxxxx>
>
> Introduce a new type of iter prog: cgroup. Unlike other bpf_iter, this
> iter doesn't iterate a set of kernel objects. Instead, it is supposed to
> be parameterized by a cgroup id and prints only that cgroup. So one
> needs to specify a target cgroup id when attaching this iter. The target
> cgroup's state can be read out via a link of this iter.
>
> Signed-off-by: Hao Luo <haoluo@xxxxxxxxxx>
> Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
> ---
>  include/linux/bpf.h            |   2 +
>  include/uapi/linux/bpf.h       |   6 ++
>  kernel/bpf/Makefile            |   2 +-
>  kernel/bpf/cgroup_iter.c       | 148 +++++++++++++++++++++++++++++++++
>  tools/include/uapi/linux/bpf.h |   6 ++
>  5 files changed, 163 insertions(+), 1 deletion(-)
>  create mode 100644 kernel/bpf/cgroup_iter.c
>

Thanks Yosry for posting this patch! Dear reviewers, this is v2 of the
cgroup_iter change I sent previously at

https://lore.kernel.org/bpf/20220225234339.2386398-9-haoluo@xxxxxxxxxx/

v1 - > v2:
- Getting the cgroup's reference at the time at attaching, instead of
at the time when iterating. (Yonghong) (context [1])
- Remove .init_seq_private and .fini_seq_private callbacks for
cgroup_iter. They are not needed now. (Yonghong)

[1] https://lore.kernel.org/bpf/f780fc3a-dbc2-986c-d5a0-6b0ef1c4311f@xxxxxx/

Hao