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SubjectRe: [patch-rt] hotplug, hrtimer: Migrate expired/deferred timers during cpu offline
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On Fri, 2017-08-11 at 10:15 +0200, Mike Galbraith wrote:
> On Fri, 2017-08-11 at 09:55 +0200, Mike Galbraith wrote:
> > The below fixes the list debug explosion up.
> >
> > If we do not migrate expired/deferred timers during cpu offline, ->cb_entry
> > will be corrupted by online initialization of base->expired, leading to a
> > loud list debug complaint should someone call __remove_hrtimer() thereafter.
> >
> > Signed-off-by: Mike Galvraith <efault@gmx.de>
> ahem.....................b

(actually, I shouldn't have signed, question being why we now leave
them lying about when we _apparently_ previously did not)

> > ---
> > kernel/time/hrtimer.c | 13 +++++++++++++
> > 1 file changed, 13 insertions(+)
> >
> > --- a/kernel/time/hrtimer.c
> > +++ b/kernel/time/hrtimer.c
> > @@ -1802,6 +1802,19 @@ static void migrate_hrtimer_list(struct
> > */
> > enqueue_hrtimer(timer, new_base);
> > }
> > +
> > + /*
> > + * Finally, migrate any expired timers deferred by RT.
> > + */
> > + while (!list_empty(&old_base->expired)) {
> > + struct list_head *entry = old_base->expired.next;
> > +
> > + timer = container_of(entry, struct hrtimer, cb_entry);

(oops, forgot to change that back too. [scribble scribble])

> > + /* XXX: hm, perhaps defer again instead of enqueueing. */
> > + __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
> > + timer->base = new_base;
> > + enqueue_hrtimer(timer, new_base);
> > + }
> > }
> >
> > int hrtimers_dead_cpu(unsigned int scpu)

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