Re: [PATCH 14/21] x86/intel_rdt/cqm: Add mon_data

[Shivappa Vikas]

On Thu, 6 Jul 2017, Thomas Gleixner wrote:

> On Thu, 6 Jul 2017, Shivappa Vikas wrote:
> > On Sun, 2 Jul 2017, Thomas Gleixner wrote:
> > > > +static bool __mon_event_count(u32 rmid, struct rmid_read *rr)
> > > > +{
> > > > +	u64 tval;
> > > > +
> > > > +	tval = __rmid_read(rmid, rr->evtid);
> > > > +	if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
> > > > +		rr->val = tval;
> > > > +		return false;
> > > > +	}
> > > > +	switch (rr->evtid) {
> > > > +	case QOS_L3_OCCUP_EVENT_ID:
> > > > +		rr->val += tval;
> > > > +		return true;
> > > > +	default:
> > > > +		return false;
> > >
> > > I have no idea what that return code means.
> >
> > false for the invalid event id and all errors for __rmid_read. (IOW all errors
> > for __mon_event-read)
>
> Sure, but why bool? What's wrong with proper error return codes, so issues
> can be distinguished and potentially propagated in the callchain?

Ok, The error is propagated wih the rr->val actually. is this better?

Hardware throws the RMID_VAL_ERROR (bit 63) when an invalid RMID or 
event is written to event select - this case seems similar.

	default:
		rr->val = RMID_VAL_ERROR;
		return -EINVAL;
	}

Thanks,
Vikas

> Thanks,
>
> 	tglx