Re: [PATCH V2 3/5] cpuidle: idle: menu: Don't reflect when a state selection failed

[Daniel Lezcano]

On 10/28/2014 03:01 AM, Len Brown wrote:
> On Thu, Oct 23, 2014 at 5:01 AM, Daniel Lezcano
> <daniel.lezcano@xxxxxxxxxx> wrote:
> > In the current code, the check to reflect or not the outcoming state is done
> > against the idle state which has been chosen and its value.
> >
> > Instead of doing a check in each of the reflect functions, just don't call reflect
> > if something went wrong in the idle path.
> >
> > Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> > Acked-by: Nicolas Pitre <nico@xxxxxxxxxx>
> > ---
> >   drivers/cpuidle/governors/ladder.c | 3 +--
> >   drivers/cpuidle/governors/menu.c   | 4 +---
> >   kernel/sched/idle.c                | 3 ++-
> >   3 files changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
> > index fb396d6..c0b36a8 100644
> > --- a/drivers/cpuidle/governors/ladder.c
> > +++ b/drivers/cpuidle/governors/ladder.c
> > @@ -165,8 +165,7 @@ static int ladder_enable_device(struct cpuidle_driver *drv,
> >   static void ladder_reflect(struct cpuidle_device *dev, int index)
> >   {
> >          struct ladder_device *ldev = &__get_cpu_var(ladder_devices);
> > -       if (index > 0)
> > -               ldev->last_state_idx = index;
>
> Before this patch, last_state_idx was never set to 0 here.
> After this patch, last_state_idx will be set to 0 when entered_state is 0.
> Is that okay?

Yes, I think so because the state zero won't be never selected on x86 
but on the other arch it will. So before this patch, on the other archs, 
the state 0 was never reflected as it should do.

This is resulting from the CPUIDLE_DRIVER_STATE_START macro (I hope I 
can kill this macro in a couple of patchset after this one).

> > +       ldev->last_state_idx = index;
> >   }
> >
> >   static struct cpuidle_governor ladder_governor = {
> > diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> > index a17515f..3907301 100644
> > --- a/drivers/cpuidle/governors/menu.c
> > +++ b/drivers/cpuidle/governors/menu.c
> > @@ -365,9 +365,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
> >   static void menu_reflect(struct cpuidle_device *dev, int index)
> >   {
> >          struct menu_device *data = &__get_cpu_var(menu_devices);
> > -       data->last_state_idx = index;
> > -       if (index >= 0)
> > -               data->needs_update = 1;
> > +       data->needs_update = 1;
> >   }
> >
> >   /**
> > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> > index 58c7522..49dcc7d 100644
> > --- a/kernel/sched/idle.c
> > +++ b/kernel/sched/idle.c
> > @@ -162,7 +162,8 @@ use_default:
> >          /*
> >           * Give the governor an opportunity to reflect on the outcome
> >           */
> > -       cpuidle_reflect(dev, entered_state);
> > +       if (entered_state >= 0)
> > +               cpuidle_reflect(dev, entered_state);
> >
> >   exit_idle:
> >          __current_set_polling();
> > --
> > 1.9.1
> >
> > --
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