Re: [PATCH v2 03/28] coresight: etm3x: Always set tracer's device mode on target CPU

[Leo Yan <leo.yan@arm.com>]

On Wed, Jul 02, 2025 at 11:18:21AM +0100, Yeoreum Yun wrote:
> Hi Leo,
> 
> [...]
> > @@ -464,17 +477,29 @@ static int etm_enable_perf(struct coresight_device *csdev,
> >  			   struct perf_event *event,
> >  			   struct coresight_path *path)
> >  {
> > +	int ret = 0;
> >  	struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> >
> > -	if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
> > -		return -EINVAL;
> > +	if (!coresight_take_mode(csdev, CS_MODE_PERF))
> > +		return -EBUSY;
> > +
> > +	if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id())) {
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> 
> Small question: why drvdata->cpu != smp_processor_id() check after
> changing mode? Would it better to check before change of it?

You are right. I will update in next version.

Thanks for pointing out this!

Leo