On Mon, Dec 13, 2021 at 12:34:55PM +0100, Frederic Weisbecker wrote:
> On Mon, Dec 13, 2021 at 11:40:24AM +0530, Neeraj Upadhyay wrote:
> > For PREEMPT_RCU, the rcu_exp_handler() function checks
> > whether the current CPU is in idle, by calling
> > rcu_dynticks_curr_cpu_in_eqs(). However, rcu_exp_handler()
> > is called in IPI handler context. So, it should be checking
> > the idle context using rcu_is_cpu_rrupt_from_idle(). Fix this
> > by using rcu_is_cpu_rrupt_from_idle() instead of
> > rcu_dynticks_curr_cpu_in_eqs(). Non-preempt configuration
> > already uses the correct check.
> >
> > Signed-off-by: Neeraj Upadhyay <quic_neeraju@xxxxxxxxxxx>
>
> Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Queued for further review and testing, thank you both!
Thanx, Paul
> > ---
> > kernel/rcu/tree_exp.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
> > index 237a79989aba..1568c8ef185b 100644
> > --- a/kernel/rcu/tree_exp.h
> > +++ b/kernel/rcu/tree_exp.h
> > @@ -656,7 +656,7 @@ static void rcu_exp_handler(void *unused)
> > */
> > if (!depth) {
> > if (!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)) ||
> > - rcu_dynticks_curr_cpu_in_eqs()) {
> > + rcu_is_cpu_rrupt_from_idle()) {
> > rcu_report_exp_rdp(rdp);
> > } else {
> > WRITE_ONCE(rdp->cpu_no_qs.b.exp, true);
> > --
> > 2.17.1
> >
