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

From: Steven Rostedt <[email-masked]>
Date: Fri, 14 Nov 2025 12:40:33 -0500

On Fri, 14 Nov 2025 09:25:06 -0800
"Paul E. McKenney" <[email-masked]> 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