Re: [PATCH 7/8] x86/intel_rdt: schemata file support for MBA prepare\

[Shivappa Vikas]

On Wed, 1 Mar 2017, Thomas Gleixner wrote:

> On Fri, 17 Feb 2017, Vikas Shivappa wrote:
>
> Subject: x86/intel_rdt: schemata file support for MBA prepare
>
> I have no idea what MBA prepare is. Is that yet another variant aside of
> MBE?
>
> > Add support to introduce generic APIs for control validation and writing
> > QOS_MSRs for RDT resources. The control validation api is meant to
> > validate the control values like cache bit mask for CAT and memory b/w
> > percentage for MBA. A resource generic display format is also added and
> > used for the resources depending on whether its displayed in
> > hex/decimal.
>
> The usual unpenetratable mess of random sentences lumped together.
>
> > diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
> > index 24de64c..8748b0d 100644
> > --- a/arch/x86/include/asm/intel_rdt.h
> > +++ b/arch/x86/include/asm/intel_rdt.h
> > @@ -77,6 +77,9 @@ struct rftype {
> >   * @default_ctrl:		Specifies default cache cbm or mem b/w percent.
> >   * @min_cbm_bits:		Minimum number of consecutive bits to be set
> >   *				in a cache bit mask
> > + * @format_str:		Per resource format string to show domain val
>
> Can you please spell out words in comments instead of using random
> abbreviations just as you see fit?
>
> > + * @parse_ctrlval:		Per resource API to parse the ctrl values
>
> That's not an API. That's a function pointer.
>
> > + * @msr_update:		API to update QOS MSRs
>
> Ditto.
>
> >   * @info_files:		resctrl info files for the resource
> >   * @infofiles_len:		Number of info files
> >   * @max_delay:			Max throttle delay. Delay is the hardware
> > @@ -105,6 +108,9 @@ struct rdt_resource {
> >  	int			cbm_len;
> >  	int			min_cbm_bits;
> >  	u32			default_ctrl;
> > +	const char		*format_str;
> > +	int (*parse_ctrlval)	(char *buf, struct rdt_resource *r);
> > +	void (*msr_update)	(void *a1, void *a2, struct rdt_resource *r);
>
> void *a1, *a2? Dammit, both implementations (CAT and MBA) use the same
> types. This just avoids type safety which does not magically come back by
> your completely nonsensical typecasts inside the callback implementations.
>
> > +void cqm_wrmsr(void *a1, void *a2, struct rdt_resource *r)
>
> And this is global because it's only used in this file, right?
>
> > +{
> > +	struct rdt_domain *d = (struct rdt_domain *)a2;
> > +	struct msr_param *m = (struct msr_param *)a1;
>
> Oh well......
>
> > +	int i;
> > +
> > +	for (i = m->low; i < m->high; i++) {
> > +		int idx = cbm_idx(r, i);
> > +
> > +		wrmsrl(r->msr_base + idx, d->ctrl_val[i]);
> > +	}
> > +}
>
> > -static bool cbm_validate(unsigned long var, struct rdt_resource *r)
> > +static int cbm_validate(char *buf, unsigned long *data, struct rdt_resource *r)
> >  {
> > -	unsigned long first_bit, zero_bit;
> > +	unsigned long first_bit, zero_bit, var;
> > +	int ret;
> > +
> > +	ret = kstrtoul(buf, 16, &var);
> > +	if (ret)
> > +		return ret;
> >
> >  	if (var == 0 || var > r->default_ctrl)
> > -		return false;
> > +		return -EINVAL;
>
> So you change this function and the whole call chain to return either
> -EINVAL or 0 instead of false/true.
>
> And then you treat the integer return value as boolean on the call site
> again:

Will fix wrt all the comments.

Thanks,
Vikas