Re: [PATCH 4/5] x86/intel_rdt: Reset the cbm MSR during rmdir

[Shivappa Vikas]

On Wed, 1 Mar 2017, Thomas Gleixner wrote:

> On Fri, 17 Feb 2017, Vikas Shivappa wrote:
>
> > During rmdir reset the ctrl values to all 1s in the QOS_MSR for the
> > directory's closid. This is done so that that next time when the closid
> > is reused they dont reflect old values.
>
> Sigh.
>
> > +static int reset_all_ctrls(struct rdt_resource *r, u32 sclosid, u32 eclosid)
>
> What's so wrong with using 'start' and 'end' instead of these cryptic names?
>
> >  {
> >  	struct msr_param msr_param;
> >  	cpumask_var_t cpu_mask;
> > @@ -791,8 +791,8 @@ static int reset_all_cbms(struct rdt_resource *r)
> >  		return -ENOMEM;
> >
> >  	msr_param.res = r;
> > -	msr_param.low = 0;
> > -	msr_param.high = r->num_closid;
> > +	msr_param.low = sclosid;
> > +	msr_param.high = eclosid;
> >
> >  	/*
> >  	 * Disable resource control for this resource by setting all
> > @@ -802,7 +802,7 @@ static int reset_all_cbms(struct rdt_resource *r)
> >  	list_for_each_entry(d, &r->domains, list) {
> >  		cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
> >
> > -		for (i = 0; i < r->num_closid; i++)
> > +		for (i = sclosid; i < eclosid; i++)
>
> 'eclosid' or even when named 'end' is an outright bogus argument to this
> function. What you really want is:
>
> static int reset_all_ctrls(struct rdt_resource *r, u32 closid, u32 count)
>
> which works here:
>
> >  	for_each_enabled_rdt_resource(r)
> > -		reset_all_cbms(r);
> > +		reset_all_ctrls(r, 0, r->num_closid);
>
> and makes this part understandable:
>
> > +	/*
> > +	 * Put domain control values back to default for the
> > +	 * rdtgrp thats being removed.
> > +	 */
> > +	for_each_enabled_rdt_resource(r)
> > +		reset_all_ctrls(r, rdtgrp->closid, rdtgrp->closid + 1);
>
> 		reset_all_ctrls(r, rdtgrp->closid, 1);

Will fix the parameters to start and count..

> What you have done:
>
> > +		reset_all_ctrls(r, rdtgrp->closid, rdtgrp->closid + 1);
>
> made me really look twice to figure out what the heck this is about.
>
> Thanks,
>
> 	tglx