[MODERATED] Re: [PATCH v3 2/6] PERFv3

On Thu, Feb 07, 2019 at 03:41:04PM -0800, speck for Andi Kleen wrote:
> +static struct event_constraint *
> +skl_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
> +			  struct perf_event *event)
> +{
> +	struct event_constraint *c;
> +
> +	c = hsw_get_event_constraints(cpuc, idx, event);
> +
> +	if (!perf_enable_all_counters) {
> +		cpuc->counter3_constraint = *c;
> +		c = &cpuc->counter3_constraint;
> +
> +		/*
> +		 * Without TFA we must not use PMC3.
> +		 */
> +		__clear_bit(3, c->idxmsk);
> +	}
> +
> +	return c;
> +}

This is obviously broken... what if all 6 events are in use and have
different constraints?