Re: [PATCH 05/36] cpuidle: Move IRQ state validation

[Rafael J. Wysocki]

On Wed, Jun 8, 2022 at 4:47 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> Make cpuidle_enter_state() consistent with the s2idle variant and
> verify ->enter() always returns with interrupts disabled.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---
>  drivers/cpuidle/cpuidle.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -234,7 +234,11 @@ int cpuidle_enter_state(struct cpuidle_d
>         stop_critical_timings();
>         if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
>                 rcu_idle_enter();
> +
>         entered_state = target_state->enter(dev, drv, index);
> +       if (WARN_ONCE(!irqs_disabled(), "%ps leaked IRQ state", target_state->enter))

I'm not sure if dumping a call trace here is really useful and
WARN_ON() often gets converted to panic().

I would print an error message with pr_warn_once().

Otherwise LGTM.

> +               raw_local_irq_disable();
> +
>         if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE))
>                 rcu_idle_exit();
>         start_critical_timings();
> @@ -246,12 +250,8 @@ int cpuidle_enter_state(struct cpuidle_d
>         /* The cpu is no longer idle or about to enter idle. */
>         sched_idle_set_state(NULL);
>
> -       if (broadcast) {
> -               if (WARN_ON_ONCE(!irqs_disabled()))
> -                       local_irq_disable();
> -
> +       if (broadcast)
>                 tick_broadcast_exit();
> -       }
>
>         if (!cpuidle_state_is_coupled(drv, index))
>                 local_irq_enable();
>
>