On Thu, Jan 21, 2021 at 10:57:57AM +0000, Vincent Donnefort wrote:
> On Wed, Jan 20, 2021 at 06:53:33PM +0100, Peter Zijlstra wrote:
> > On Wed, Jan 20, 2021 at 06:45:16PM +0100, Peter Zijlstra wrote:
> > > On Mon, Jan 11, 2021 at 05:10:46PM +0000, vincent.donnef...@arm.com wrote:
> > > > @@ -475,6 +478,11 @@ cpuhp_set_state(struct cpuhp_cpu_state *st, enum
> > > > cpuhp_state target)
> > > > static inline void
> > > > cpuhp_reset_state(struct cpuhp_cpu_state *st, enum cpuhp_state
> > > > prev_state)
> > > > {
> > > > + st->target = prev_state;
> > > > +
> > > > + if (st->rollback)
> > > > + return;
> > >
> > > I'm thinking that if we call rollback while already rollback we're hosed
> > > something fierce, no?
> > >
> > > That like going up, failing, going back down again, also failing, giving
> > > up in a fiery death.
> >
> > Ooh, is this a hack for _cpu_down():
> >
> > ret = cpuhp_down_callbacks(cpu, st, target);
> > if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) {
> > cpuhp_reset_state(st, prev_state);
> > __cpuhp_kick_ap(st);
> > }
> >
> > Where cpuhp_down_callbacks() can already have called cpuhp_reset_state() ?
>
> Yes, it is now possible that this function will be called twice during the
> rollback. Shall I avoid this and treat the case above differently ? i.e. "if
> we
> are here, state has already been reset, and we should only set st->target".
Not sure, but a comment would be useful :-)
