linux-kernel - Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAADnVQJMa+p_BcYxKUgve2=sqRBwSs3wLGAGhbA0r6hwFpJ+6Q@mail.gmail.com>
Date: Fri, 9 Jan 2026 11:10:16 -0800
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, LKML <linux-kernel@...r.kernel.org>, 
	Linux trace kernel <linux-trace-kernel@...r.kernel.org>, bpf <bpf@...r.kernel.org>, 
	Masami Hiramatsu <mhiramat@...nel.org>, "Paul E. McKenney" <paulmck@...nel.org>, 
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of
 __DO_TRACE_CALL() with SRCU-fast

On Fri, Jan 9, 2026 at 6:45 AM Mathieu Desnoyers
<mathieu.desnoyers@...icios.com> wrote:
>
> On 2026-01-08 22:05, Steven Rostedt wrote:
> > From: "Paul E. McKenney" <paulmck@...nel.org>
> [...]
>
> I disagree with many elements of the proposed approach.
>
> On one end we have BPF wanting to hook on arbitrary tracepoints without
> adding significant latency to PREEMPT RT kernels.
>
> One the other hand, we have high-speed tracers which execute very short
> critical sections to serialize trace data into ring buffers.
>
> All of those users register to the tracepoint API.
>
> We also have to consider that migrate disable is *not* cheap at all
> compared to preempt disable.

Looks like your complaint comes from lack of engagement in kernel
development.
migrate_disable _was_ not cheap.
Try to benchmark it now.
It's inlined. It's a fraction of extra overhead on top of preempt_disable.