Re: [PATCH v2] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook

[Steven Rostedt]

On Tue, 11 Feb 2020 16:34:52 +0100
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> > +		if (unlikely(in_nmi()))
> > +			goto out;  
> 
> unless I'm mistaken, we can simply do rcu_nmi_enter() in this case, and
> rcu_nmi_exit() on the other end.
> 
> > +		rcu_irq_enter_irqson();

The thing is, I don't think this can ever happen. We've had in the
tracepoint.h:

		/* srcu can't be used from NMI */			\
		WARN_ON_ONCE(rcuidle && in_nmi());			\

And this has yet to trigger.

-- Steve