linux-kernel - Re: [PATCH 3/4] rtla/timerlat: Add example for BPF action program

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: <20251021130232.2ca75863@gandalf.local.home>
Date: Tue, 21 Oct 2025 13:02:32 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Crystal Wood <crwood@...hat.com>
Cc: Tomas Glozar <tglozar@...hat.com>, LKML <linux-kernel@...r.kernel.org>,
 Linux Trace Kernel <linux-trace-kernel@...r.kernel.org>, John Kacur
 <jkacur@...hat.com>, Luis Goncalves	 <lgoncalv@...hat.com>, Costa Shulyupin
 <costa.shul@...hat.com>, Wander Lairson Costa <wander@...hat.com>, Arnaldo
 Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH 3/4] rtla/timerlat: Add example for BPF action program

On Tue, 21 Oct 2025 10:58:06 -0500
Crystal Wood <crwood@...hat.com> wrote:

> Huh, so I guess BPF is an exception to the "no generic printk to the
> global trace instance except for debugging that generates a big boot
> splat" rule?

bpf_printk() is an event and not the generic trace_printk() that would
cause that splat. You can turn it off.

> 
> Speaking of which, why doesn't trace_osnoise.c call
> trace_array_init_printk() given that it uses trace_array_printk_buf()?

Note, trace_array_printk() (which trace_array_init_printk()) only works for
instances and does not print into the top level trace buffer.

-- Steve