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References: <20220104080943.113249-1-jolsa@kernel.org> <20220106002435.d73e4010c93462fbee9ef074@kernel.org>
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In-Reply-To: <20220106225943.87701fcc674202dc3e172289@kernel.org>
From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Thu, 6 Jan 2022 09:40:17 -0800
Message-ID: <CAADnVQLjjcsckQVqaSB8ODB4FKdVUt-PB9xyJ3FAa2GWGLbHgA@mail.gmail.com>
Subject: Re: [RFC 00/13] kprobe/bpf: Add support to attach multiple kprobes
To:     Masami Hiramatsu <mhiramat@kernel.org>
Cc:     Jiri Olsa <jolsa@redhat.com>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>, lkml <linux-kernel@vger.kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
        "David S. Miller" <davem@davemloft.net>
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On Thu, Jan 6, 2022 at 5:59 AM Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> That seems to bind your mind. The program type is just a programing
> 'model' of the bpf. You can choose the best implementation to provide
> equal functionality. 'kprobe' in bpf is just a name that you call some
> instrumentations which can probe kernel code.

No. We're not going to call it "fprobe" or any other name.
>From bpf user's pov it's going to be "multi attach kprobe",
because this is how everyone got to know kprobes.
The 99% usage is at the beginning of the funcs.
When users say "kprobe" they don't care how kernel attaches it.
The func entry limitation for "multi attach kprobe" is a no-brainer.

And we need both "multi attach kprobe" and "multi attach kretprobe"
at the same time. It's no go to implement one first and the other
some time later.