Re: [PATCH 5/6] perf/core: Use ioctl to communicate driver configuration to kernel

[Jiri Olsa]

On Mon, Jul 02, 2018 at 04:33:29PM -0600, Mathieu Poirier wrote:

SNIP

> +static int
> +perf_event_process_drv_config(struct perf_event *event, char *config_str)
> +{
> +	int ret = -EINVAL;
> +	void *drv_data;
> +
> +	/* Make sure ctx.mutex it held */
> +	lockdep_assert_held(&event->ctx->mutex);
> +
> +	/* Children take their configuration from their parent */
> +	if (WARN_ON_ONCE(event->parent))
> +		goto out;
> +
> +	drv_data = event->pmu->drv_config_validate(event, config_str);
> +	if (!drv_data)
> +		goto out;

what's this check for? doc does not mention that,
also the coresight callback does not return NULL

jirka