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

[Daniel Lezcano]

On 10/28/2014 08:01 AM, Preeti Murthy wrote:
> On Thu, Oct 23, 2014 at 2:31 PM, 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;
> > +       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;
>
> Why is the last_state_idx not getting updated ?

Oups, right. This is missing.

Thanks for pointing this out.

By the way, I don't think a back end driver is changing the selected 
state currently and I am not sure this is desirable since we want to 
trust the state we are going (as a best effort). So if the 'enter' 
function does not change the index, that means the last_state_idx has 
not to be changed since it has been assigned in the 'select' function.



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