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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Wed, 18 Sep 2019 13:22:18 -0700
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Subject: Re: [PATCH] staging: tracing/kprobe: filter kprobe based perf event
To:     Jinshan Xiong <jinshan.xiong@uber.com>
Cc:     Yonghong Song <yhs@fb.com>,
        "jinshan.xiong@gmail.com" <jinshan.xiong@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "rostedt@goodmis.org" <rostedt@goodmis.org>,
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        "bpf@vger.kernel.org" <bpf@vger.kernel.org>
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On Wed, Sep 18, 2019 at 8:13 AM Jinshan Xiong <jinshan.xiong@uber.com> wrote:
>
> The problem with the current approach is that it would be difficult to filter cgroup, especially the cgroup in question has descendents, and also it would spawn new descendents after BPF program is installed. it's hard to filter it inside a BPF program.

Why is that?
bpf_current_task_under_cgroup() fits exactly that purpose.