linux-kernel - Re: [PATCH 5/8] x86/intel_rct/mba: Add MBA structures and initialize MBA

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Date:   Tue, 17 Jan 2017 16:56:04 -0800 (PST)
From:   Shivappa Vikas <vikas.shivappa@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
cc:     Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        vikas.shivappa@...el.com, linux-kernel@...r.kernel.org,
        x86@...nel.org, hpa@...or.com, mingo@...nel.org,
        peterz@...radead.org, ravi.v.shankar@...el.com,
        tony.luck@...el.com, fenghua.yu@...el.com, h.peter.anvin@...el.com
Subject: Re: [PATCH 5/8] x86/intel_rct/mba: Add MBA structures and initialize
 MBA



On Mon, 16 Jan 2017, Thomas Gleixner wrote:

> On Tue, 10 Jan 2017, Vikas Shivappa wrote:
>> +static void rdt_get_mem_config(struct rdt_resource *r)
>> +{
>> +	union cpuid_0x10_3_eax eax;
>> +	union cpuid_0x10_x_edx edx;
>> +	u32 ebx, ecx;
>> +
>> +	cpuid_count(0x00000010, 3, &eax.full, &ebx, &ecx, &edx.full);
>> +	r->num_closid = edx.split.cos_max + 1;
>> +	r->max_delay = eax.split.max_delay + 1;
>> +	r->no_ctrl = 0;
>> +	if (ecx & MBE_IS_LINEAR)
>> +		r->delay_linear = true;
>> +
>> +	if (r->delay_linear)
>> +		r->delay_gran = MAX_MBA_THRTL - r->max_delay;
>
> What's the point of this extra conditional?
>
> 	if (ecx & MBE_IS_LINEAR) {
> 		r->delay_linear = true;
> 		r->delay_gran = MAX_MBA_THRTL - r->max_delay;
> 	}
>
> would be too obvious and easy to understand, right?

Will fix.

>
>> +static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain *d)
>> +{
>> +	int i;
>> +
>> +	d->ctrl_val = kmalloc_array(r->num_closid,
>> +				     sizeof(*d->ctrl_val), GFP_KERNEL);
>> +	if (!d->ctrl_val) {
>> +		kfree(d);
>
> Freeing memory in the error path of some other random function is just wrong.
>
> 	if (!d->ctrl_val)
> 		return -ENOMEM;
>
> and deal with the fallout at the calling function.

Will fix.. Thanks for pointing out.

Vikas

>
> Thanks,
>
> 	tglx
>