On Fri, Aug 02, 2019 at 05:20:38PM +0800 Hillf Danton wrote:
>
> On Thu, 1 Aug 2019 09:37:49 -0400 Phil Auld wrote:
> >
> > Enabling WARN_DOUBLE_CLOCK in /sys/kernel/debug/sched_features causes
> > warning to fire in update_rq_clock. This seems to be caused by onlining
> > a new fair sched group not using the rq lock wrappers.
> >
> > [472978.683085] rq->clock_update_flags & RQCF_UPDATED
> > [472978.683100] WARNING: CPU: 5 PID: 54385 at kernel/sched/core.c:210
> > update_rq_clock+0xec/0x150
>
> Another option perhaps only if that wrappers are not mandatory.
>
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -212,10 +212,14 @@ void update_rq_clock(struct rq *rq)
> #endif
>
> delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
> - if (delta < 0)
> - return;
> - rq->clock += delta;
> - update_rq_clock_task(rq, delta);
> + if (delta >= 0) {
> + rq->clock += delta;
> + update_rq_clock_task(rq, delta);
> + }
> +
> +#ifdef CONFIG_SCHED_DEBUG
> + rq->clock_update_flags &= ~RQCF_UPDATED;
> +#endif
> }
>
>
> --
>
I think that would silence the warning, but...
If we're to clear that flag right there, outside of the lock pinning code,
then I think we might as well just remove the flag and all associated
comments etc, no?
Cheers,
Phil
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