Re: [PATCH v2 03/11] sched,idle,rcu: Push rcu_idle deeper into the idle path

[peterz]

On Thu, Aug 27, 2020 at 06:30:01PM -0400, Joel Fernandes wrote:
> On Thu, Aug 27, 2020 at 09:47:48AM +0200, peterz@xxxxxxxxxxxxx wrote:

> > All trace_*_rcuidle() and RCU_NONIDLE() usage is a bug IMO.
> > 
> > Ideally RCU-trace goes away too.
> 
> I was thinking that unless the rcu_idle_enter/exit calls coincide with points
> in the kernel where instrumentation is not allowed, there is always a chance
> somebody wants to use tracepoints after rcu_idle_enter or before exit. In
> this case, trace_*_rcuidle() is unavoidable unless you can move the
> rcu_idle_enter/exit calls deeper as you are doing.
> 
> Maybe objtool can help with that?

The eventual goal is to mark idle code noinstr too. There's more work
before we can do that.