linux-kernel - Re: [PATCH V6 07/38] x86/intel_rdt: Initialize new resource group with sane defaults

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Message-ID: <alpine.DEB.2.21.1806191418460.1684@nanos.tec.linutronix.de>
Date:   Tue, 19 Jun 2018 14:31:07 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Reinette Chatre <reinette.chatre@...el.com>
cc:     fenghua.yu@...el.com, tony.luck@...el.com,
        vikas.shivappa@...ux.intel.com, gavin.hindman@...el.com,
        jithu.joseph@...el.com, dave.hansen@...el.com, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V6 07/38] x86/intel_rdt: Initialize new resource group
 with sane defaults

On Thu, 7 Jun 2018, Reinette Chatre wrote:
> +/**
> + * cbm_ensure_valid - Enforce validity on provided CBM
> + * @_val:	Candidate CBM
> + * @r:		RDT resource to which the CBM belongs
> + *
> + * The provided CBM represents all cache portions available for use. This
> + * may be represented by a bitmap that does not consist of contiguous ones
> + * and thus be an invalid CBM.
> + * Here the provided CBM is forced to be a valid CBM by only considering
> + * the first set of contiguous bits as valid and clearing all bits.
> + * The intention here is to provide a valid default CBM with which a new
> + * resource group is initialized. The user can follow this with a
> + * modification to the CBM if the default does not satisfy the
> + * requirements.
> + */
> +static void cbm_ensure_valid(u32 *_val, struct rdt_resource *r)
> +{
> +	unsigned long *val = (unsigned long *)_val;

I'm a bit worried about the u32 to unsigned long case here. I know that
cbm_len cannot exceed 32, but still. At least it wants a comment.

Thanks,

	tglx