On Tue, Sep 29, 2015 at 02:55:13PM +0200, Frederic Weisbecker wrote:
> On Tue, Sep 29, 2015 at 11:28:27AM +0200, Peter Zijlstra wrote:
> > #define init_task_preempt_count(p) do { \
> > - task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \
> > + task_thread_info(p)->preempt_count = 2*PREEMPT_DISABLED; \
>
> Since it's not quite obvious why we use this magic value without looking
> at schedule_tail() details, maybe add a little comment? (Just "/* see
> schedule_tail() */").
Right, I fixed that in 12/11 v2. I'll change that around a bit.
> > + /*
> > + * Still have preempt_count() == 2, from:
> > + *
> > + * schedule()
> > + * preempt_disable(); // 1
> > + * __schedule()
> > + * raw_spin_lock_irq(&rq->lock) // 2
> > + */
>
> I found that a bit confusing first, because that's a preempt_count()
> we actually emulate for a new task. Maybe something like:
>
> + /*
> + * New task is init with preempt_count() == 2 because prev task left
> + * us after:
> + *
> + * schedule()
> + * preempt_disable(); // 1
> + * __schedule()
> + * raw_spin_lock_irq(&rq->lock) // 2
> + */
I think I'll move the comment to finish_task_switch(), but yes.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
