linux-kernel - Re: [RFC PATCH bpf-next v1 0/3] bpf: Add BPF program type for overriding tracepoint probes

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Message-ID: <787f5dff-7ac0-4193-a5c9-5eafa9a7b4e5@vivo.com>
Date: Fri, 19 Sep 2025 21:00:27 +0800
From: Fuyu Zhao <zhaofuyu@...o.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Jiri Olsa <olsajiri@...il.com>, Song Liu <song@...nel.org>,
 ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
 martin.lau@...ux.dev, yonghong.song@...ux.dev, haoluo@...gle.com,
 eddyz87@...il.com, kpsingh@...nel.org, sdf@...ichev.me, mhiramat@...nel.org,
 mathieu.desnoyers@...icios.com, shuah@...nel.org, willemb@...gle.com,
 kerneljasonxing@...il.com, paul.chaignon@...il.com, chen.dylane@...ux.dev,
 memxor@...il.com, martin.kelly@...wdstrike.com, ameryhung@...il.com,
 linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
 yikai.lin@...o.com
Subject: Re: [RFC PATCH bpf-next v1 0/3] bpf: Add BPF program type for
 overriding tracepoint probes



On 9/18/2025 11:32 PM, Steven Rostedt wrote:
> On Thu, 18 Sep 2025 21:15:57 +0800
> Fuyu Zhao <zhaofuyu@...o.com> wrote:
> 
>> As for the reason not to unregister and register a new callback:
>> callbacks registered directly inside the kernel cannot be unregistered from
>> user space. From user space, we can only attach additional callbacks
>> with BPF programs, but can not remove or replace the ones already
>> registered in the kernel. Therefore, an override mechanism is needed.
> 
> The fact that user space cannot unregister or override the current
> callbacks, to me is a feature and not a bug.
> 
> -- Steve

I see, thank you for sharing your view — I’ll keep it in mind.

Sincerely,
Fuyu