Re: [Patch v3 3/7] perf/x86: Check if cpuc->events[*] pointer exists before accessing it

[Andi Kleen]

>  		event = cpuc->events[bit];
> +		/*
> +		 * perf_event_overflow() called by below __intel_pmu_pebs_last_event()
> +		 * could trigger interrupt throttle and clear all event pointers of the
> +		 * group in cpuc->events[] to NULL. So need to re-check if cpuc->events[*]
> +		 * is NULL, if so it indicates the event has been throttled (stopped) and
> +		 * the corresponding last PEBS records have been processed in stopping
> +		 * event, don't need to process it again.
> +		 */
> +		if (!event)
> +			continue;

Then we silently ignore the overflow. Would be better to log at least an overflow
packet or something like that.

-Andi