linux-kernel - Re: [PATCH v2] x86: xen: remove the use of VLAIS

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Date:   Mon, 8 Jan 2018 07:54:05 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Nick Desaulniers <nick.desaulniers@...il.com>
Cc:     ghackmann@...gle.com, mka@...gle.com, kees@...gle.com,
        srhines@...gle.com, Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86: xen: remove the use of VLAIS

On 06/01/18 22:39, Nick Desaulniers wrote:
> Variable Length Arrays In Structs (VLAIS) is not supported by Clang, and
> frowned upon by others.
> 
> https://lkml.org/lkml/2013/9/23/500
> 
> Here, the VLAIS was used because the size of the bitmap returned from
> xen_mc_entry() depended on possibly (based on kernel configuration)
> runtime sized data. Rather than declaring args as a VLAIS then calling
> sizeof on *args, we calculate the appropriate sizeof args manually.
> Further, we can get rid of the #ifdef's and rely on num_possible_cpus()
> (thanks to a helpful checkpatch warning from an earlier version of this
> patch).
> 
> Suggested-by: Juergen Gross <jgross@...e.com>
> Signed-off-by: Nick Desaulniers <nick.desaulniers@...il.com>

Reviewed-by: Juergen Gross <jgross@...e.com>


Juergen