On Wed, Jan 20, 2021 at 11:49:38PM +0000, Zhou Ti (x2019cwm) wrote: > Fix the issue that the tick_nohz_get_sleep_length() function could return a > negative value. > > The variable "dev->next_event" has a small possibility to be smaller than > the variable "now" during running, which would result in a negative value > of "*delta_next". The variable "next_event" also has a small posibility to > be smaller than the variable "now". Both case could lead to a negative > return of function tick_nohz_get_sleep_length().
Makes sense, queued, thanks! > > Signed-off-by: Ti Zhou <x2019...@stfx.ca> > --- > --- tip/kernel/time/tick-sched.c.orig 2021-01-20 05:34:25.151325912 -0400 > +++ tip/kernel/time/tick-sched.c 2021-01-20 19:44:28.238538380 -0400 > @@ -1142,6 +1142,9 @@ ktime_t tick_nohz_get_sleep_length(ktime > > *delta_next = ktime_sub(dev->next_event, now); > > + if (unlikely(*delta_next < 0)) > + *delta_next = 0; > + > if (!can_stop_idle_tick(cpu, ts)) > return *delta_next; > > @@ -1156,6 +1159,9 @@ ktime_t tick_nohz_get_sleep_length(ktime > next_event = min_t(u64, next_event, > hrtimer_next_event_without(&ts->sched_timer)); > > + if (unlikely(next_event < now)) > + next_event = now; > + > return ktime_sub(next_event, now); > } >
