Re: [PATCH v2 03/14] perf: Add persistent event facilities

[Peter Zijlstra <peterz@infradead.org>]

> +static void del_persistent_event(int cpu, struct perf_event_attr *attr)
> +{
> +	struct pers_event_desc *desc, *tmp;
> +	struct perf_event *event = NULL;
> +
> +	list_for_each_entry_safe(desc, tmp, &per_cpu(pers_events, cpu), plist) {
> +		if (desc->attr->config == attr->config) {

attr->config might not be enough; you might also want to compare type,
config1, config2, and possible bp_type as well; although I think we want
to avoid having hwbp style persistent events, but then what do I know.

> +			event = desc->event;
> +			break;
> +		}
> +	}
> +
> +	if (!event)
> +		return;
> +
> +	list_del(&desc->plist);
> +
> +	perf_event_disable(event);
> +	if (event->rb) {
> +		rb_put(event->rb);
> +		rcu_assign_pointer(event->rb, NULL);
> +	}
> +
> +	perf_event_release_kernel(event);
> +	put_unused_fd(desc->fd);
> +	kfree(desc->attr);
> +	kfree(desc);
> +}