[PATCH 13/13] rtems: Avoid potential recursion in ASR handling

[Gedare Bloom]

On Fri, Feb 19, 2021 at 9:35 AM Gedare Bloom <gedare at rtems.org> wrote:
>
> On Thu, Feb 18, 2021 at 11:59 PM Sebastian Huber
> <sebastian.huber at embedded-brains.de> wrote:
> >
> > On 18/02/2021 18:49, Gedare Bloom wrote:
> >
> > >> +  executing->cpu_time_budget = normal_cpu_time_budget ;
> > >> +  executing->budget_algorithm = normal_budget_algorithm ;
> > >> +  prev_is_preemptible = executing->is_preemptible;
> > > 'prev' is unclear here, especially since we have "normal" as a
> > > previous mode also. Maybe, 'asr_is_preemptible' is better?
> > >
> > No, normal is not necessarily the previous mode. The ASR handler may
> > change the mode. I can name it previous_is_preemptible if you don't like
> > the prev. asr_is_preemptible doesn't fit, since this is the mode set up
> > before the ASR handler is called.

I think I misunderstood this. Is it guaranteed that after the ASR
returns, executing->is_preemptible is the same as it was before the
ASR?

In that case, maybe the prev_is_preemptible should be copied from
executing->is_preemptible *before* making the ASR call?

> >
>
> I guess I just get a little confused between what "previous" means in
> this case. Normal mode is "previous" to the ASR call, and you are
> copying the executing->is_preemptible that may have been changed by
> the ASR, so what is this "previous" to? It doesn't make sense to me.
>
> I don't mind 'prev' as an abbreviation of previous. I just don't know
> what this is_preemptible variable is "previous" to?
>
> I guess there are three points here...
>
> Before the ASR
> In the ASR
> Dispatching after the ASR
> Returning to the original caller
>
> So, you can't say "previous" since there are 2 things in the middle.
>
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