On Wed, Jun 20, 2018 at 09:33:09AM -0400, Steven Rostedt wrote:
> On Wed, 20 Jun 2018 17:47:19 +0900
> Byungchul Park <byungchul.p...@lge.com> wrote:
>
> > Get rid of dependency on ->dynticks_nmi_nesting.
>
> This is not a trivial change. Can you please explain the rational and
> background in the change log. Add enough context here to know why this
> change is needed.
What Steve said!!!
Thanx, Paul
> Thanks!
>
> -- Steve
>
> >
> > Signed-off-by: Byungchul Park <byungchul.p...@lge.com>
> > ---
> > kernel/rcu/tree.c | 22 ++++++++++------------
> > 1 file changed, 10 insertions(+), 12 deletions(-)
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index deb2508..59ae94e 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -797,6 +797,11 @@ void rcu_nmi_exit(void)
> > return;
> > }
> >
> > + if (!in_nmi()) {
> > + rcu_prepare_for_idle();
> > + rcu_dynticks_task_enter();
> > + }
> > +
> > /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
> > trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0,
> > rdtp->dynticks);
> > WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
> > @@ -824,14 +829,8 @@ void rcu_nmi_exit(void)
> > */
> > void rcu_irq_exit(void)
> > {
> > - struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> > -
> > lockdep_assert_irqs_disabled();
> > - if (rdtp->dynticks_nmi_nesting == 1)
> > - rcu_prepare_for_idle();
> > rcu_nmi_exit();
> > - if (rdtp->dynticks_nmi_nesting == 0)
> > - rcu_dynticks_task_enter();
> > }
> >
> > /*
> > @@ -944,6 +943,11 @@ void rcu_nmi_enter(void)
> > if (rcu_dynticks_curr_cpu_in_eqs()) {
> > rcu_dynticks_eqs_exit();
> > incby = 1;
> > +
> > + if (!in_nmi()) {
> > + rcu_dynticks_task_exit();
> > + rcu_cleanup_after_idle();
> > + }
> > }
> > trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
> > rdtp->dynticks_nmi_nesting,
> > @@ -977,14 +981,8 @@ void rcu_nmi_enter(void)
> > */
> > void rcu_irq_enter(void)
> > {
> > - struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> > -
> > lockdep_assert_irqs_disabled();
> > - if (rdtp->dynticks_nmi_nesting == 0)
> > - rcu_dynticks_task_exit();
> > rcu_nmi_enter();
> > - if (rdtp->dynticks_nmi_nesting == 1)
> > - rcu_cleanup_after_idle();
> > }
> >
> > /*
>
