Re: [PATCH RFC v2 tip/core/rcu 14/22] rcu-tasks: Add an RCU Tasks Trace to simplify protection of tracing hooks

Joel Fernandes
2020-03-28T14:06:39Z

On Thu, Mar 19, 2020 at 07:41:53PM -0700, Paul E. McKenney wrote:
> On Thu, Mar 19, 2020 at 08:48:38PM -0400, Steven Rostedt wrote:
> > On Thu, 19 Mar 2020 17:28:13 -0700
> > "Paul E. McKenney" <paulmck@kernel.org> wrote:
> >
> > > Good point. If interrupts are disabled, it will need to use some
> > > other mechanism. One approach is irqwork. Another is a timer.
> > >
> > > Suggestions?
> >
> > Ftrace and perf use irq_work, I would think that should work here too.
>
> Sounds good, will give it a go! And thank you for catching this!

Since the the Tasks-RCU holdout thread is supposed to wake up periodically to
scan holdout tasks anyway, can it not detect the end of the Trace-RCU grace
period on its next wake up? Sorry if I missed something.

thanks,

- Joel