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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Tue, 29 Mar 2022 12:50:40 -0700
Message-ID: <CAADnVQ+XpoCjL-rSz2hj05L21s8NtMJuWYC14b9Mvk7XE5KT_g@mail.gmail.com>
Subject: Re: [PATCH] tracing/user_events: Add eBPF interface for user_event
 created events
To:     Beau Belgrave <beaub@linux.microsoft.com>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        linux-trace-devel <linux-trace-devel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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On Tue, Mar 29, 2022 at 11:19 AM Beau Belgrave
<beaub@linux.microsoft.com> wrote:
>
> Send user_event data to attached eBPF programs for user_event based perf
> events.
>
> Add BPF_ITER flag to allow user_event data to have a zero copy path into
> eBPF programs if required.
>
> Update documentation to describe new flags and structures for eBPF
> integration.
>
> Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>

The commit describes _what_ it does, but says nothing about _why_.
At present I see no use out of bpf and user_events connection.
The whole user_events feature looks redundant to me.
We have uprobes and usdt. It doesn't look to me that
user_events provide anything new that wasn't available earlier.