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Subject: Re: [RFC PATCH bpf-next 1/3] bpf: Enable bpf_cgrp_storage for cgroup1
 non-attach case
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To: Yafang Shao <laoar.shao@gmail.com>, ast@kernel.org, daniel@iogearbox.net,
 john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev,
 song@kernel.org, kpsingh@kernel.org, sdf@google.com, haoluo@google.com,
 jolsa@kernel.org, tj@kernel.org
Cc: bpf@vger.kernel.org, cgroups@vger.kernel.org
References: <20231205143725.4224-1-laoar.shao@gmail.com>
 <20231205143725.4224-2-laoar.shao@gmail.com>
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From: Yonghong Song <yonghong.song@linux.dev>
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On 12/5/23 9:37 AM, Yafang Shao wrote:
> In the current cgroup1 environment, associating operations between a cgroup
> and applications in a BPF program requires storing a mapping of cgroup_id
> to application either in a hash map or maintaining it in userspace.
> However, by enabling bpf_cgrp_storage for cgroup1, it becomes possible to
> conveniently store application-specific information in cgroup-local storage
> and utilize it within BPF programs. Furthermore, enabling this feature for
> cgroup1 involves minor modifications for the non-attach case, streamlining
> the process.
>
> However, when it comes to enabling this functionality for the cgroup1
> attach case, it presents challenges. Therefore, the decision is to focus on
> enabling it solely for the cgroup1 non-attach case at present. If
> attempting to attach to a cgroup1 fd, the operation will simply fail with
> the error code -EBADF.
>
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>

Acked-by: Yonghong Song <yonghong.song@linux.dev>