linux-kernel - Re: [PATCH 1/9] x86/intel_rdt: Fix MBA parsing callback

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Date:   Sat, 15 Sep 2018 12:13:53 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Fenghua Yu <fenghua.yu@...el.com>
cc:     Ingo Molnar <mingo@...hat.com>, H Peter Anvin <hpa@...or.com>,
        Tony Luck <tony.luck@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        Xiaochen Shen <xiaochen.shen@...el.com>,
        Chen Yu <yu.c.chen@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH 1/9] x86/intel_rdt: Fix MBA parsing callback

On Fri, 14 Sep 2018, Fenghua Yu wrote:
>  int parse_cbm(void *_data, struct rdt_resource *r, struct rdt_domain *d);
> -int parse_bw(void *_buf, struct rdt_resource *r,  struct rdt_domain *d);
> +int parse_bw(void *_data, struct rdt_resource *r, struct rdt_domain *d);

Sorry no. This keeps the code equally error prone as it was. Why is that
argument a void pointer in the first place? 

>  extern struct mutex rdtgroup_mutex;
>  
> diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
> index af358ca05160..d427c86e7cd0 100644
> --- a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
> @@ -28,6 +28,11 @@
>  #include <linux/slab.h>
>  #include "intel_rdt.h"
>  
> +struct rdt_parse_data {
> +	struct rdtgroup		*rdtgrp;
> +	char			*buf;
> +};

This is a copy of rdt_cbm_parse_data. Sigh.

The right thing to do here is

    1) rename struct rdt_cbm_parse_data to struct rdt_parse_data

    2) Move it to a header file

    3) Change the argument of parse_ctrlval from void * to struct
       rdt_parse_data *

Everything else is just proliferating the initial underlying problem of
having a void pointer in those callbacks for no reason at all.

Thanks,

	tglx