linux-kernel - Re: linux-next: manual merge of the rcu tree with the ftrace tree

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: <20251114124033.78500cf3@gandalf.local.home>
Date: Fri, 14 Nov 2025 12:40:33 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Stephen Rothwell
 <sfr@...b.auug.org.au>, Frederic Weisbecker <frederic@...nel.org>, Neeraj
 Upadhyay <neeraj.upadhyay@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
 Uladzislau Rezki <urezki@...il.com>, Masami Hiramatsu
 <mhiramat@...nel.org>, Linux Kernel Mailing List
 <linux-kernel@...r.kernel.org>, Linux Next Mailing List
 <linux-next@...r.kernel.org>, yonghong.song@...ux.dev
Subject: Re: linux-next: manual merge of the rcu tree with the ftrace tree

On Fri, 14 Nov 2025 09:25:06 -0800
"Paul E. McKenney" <paulmck@...nel.org> wrote:

> > This means srcu_read_lock_notrace() is much more overhead compared to
> > rcu_read_lock_sched_notrace()?
> > I am a bit afraid of different bugs here and there.  
> 
> No, the concern is instead overhead due to any actual preemption.  So the
> goal is to actually disable preemption across the BPF program *except*
> in PREEMPT_RT kernels.

If this is a BPF issue only, can we move this logic into the tracepoint
callbacks that BPF uses?

Because, as we can see in this patch. This logic has a ripple effect
throughout the tracing code where it may not be needed.

I see that the callbacks seem to call the bpf_func directly. Could there be
some kind of wrapper around these?

-- Steve