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SubjectRe: [PATCH] Scheduler: Removed first parameter from prepare_lock_switch
> On Wed, Dec 06, 2017 at 09:50:19PM -0200, Rodrigo Siqueira wrote:
> > > Yes, this is correct. However it had me looking at that code and pretty
> > > much everything else is completely wrong :-)
> > >
> > > That is, its functionally correct (probably), but the function name is
> > > not descriptive of what the function does and the comment is just plain
> > > wrong.
> > >
> > > Also, since both functions are only used in core.c we should probably
> > > move them there.
> >
> > I'm not sure I understood it completely. What do you mean for wrong? Will
> > CONFIG_SMP a meaningless check here?
>
> So the actual effective code is ok; including the #ifdef for SMP. But
> the comment is complete nonsense.
>
> Look at the comments:
>
> - in finish_lock_switch() doing smp_store_release()
> - before try_to_wake_up() describing migration/blocking
> - in try_to_wake_up() doing smp_cond_load_acquire().
>
> To get a feeling for what on_cpu actually does; it doesn't have anything
> much to do with SMP rebalancing code from interrupt contexts (although
> that too still cares through can_migrate_task() <- task_running()).
>
> > How about moving 'prepare_lock_switch' code from sched.h to prepare_task_switch
> > in core.c?
>
> With a rename; yes. Maybe something like 'acquire_task()' would do.
>
> Then split the smp_store_release() out from finish_lock_switch() and
> call it release_task(), and place is near the new acquire_task()
> function -- don't forget to update all comments referring to
> finish_lock_switch().
>
> This then leaves the actual rq->lock fiddling in finish_lock_switch();
> and that whole function too can be moved to core.c, somewhere near
> finish_task_switch() I think.

Got it! I am working on it.

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