linux-kernel - Re: [PATCH 4/8] x86/platform/uv: Setup UV functions for Hubless UV Systems

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Date:   Wed, 11 Sep 2019 13:44:19 -0700
From:   Mike Travis <mike.travis@....com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@...radead.org>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Russ Anderson <russ.anderson@....com>,
        Hedi Berriche <hedi.berriche@....com>,
        Steve Wahl <steve.wahl@....com>,
        Justin Ernst <justin.ernst@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/8] x86/platform/uv: Setup UV functions for Hubless UV
 Systems



On 9/10/2019 11:07 PM, Ingo Molnar wrote:
> 
> * Mike Travis <mike.travis@....com> wrote:
> 
>> +/* Initialize UV hubless systems */
>> +static __init int uv_system_init_hubless(void)
>> +{
>> +	int rc;
>> +
>> +	/* Setup PCH NMI handler */
>> +	uv_nmi_setup_hubless();
>> +
>> +	/* Init kernel/BIOS interface */
>> +	rc = uv_bios_init();
>> +
>> +	return rc;
>> +}

This looks like an excessive cleanup error by me.  The original was:

> +static __init int uv_system_init_hubless(void)
> +{
> +       int rc;
> +
> +       /* Setup PCH NMI handler */
> +       uv_nmi_setup_hubless();
> +
> +       /* Init kernel/BIOS interface */
> +       rc = uv_bios_init();
> +
> +       /* Create user access node if UVsystab available */
> +       if (rc >= 0)
> +               uv_setup_proc_files(1);
> +
> +       return rc;
> +}
> +

Hubbed UV's do not have a non-UV BIOS, but hubless systems in theory 
can.   So uv_bios_init can fail on hubless systems if it has some other 
BIOS (unlikely but possible).  So I removed too much in this cleanup. 
I'll send another patch set to puts this back.

Thanks,
Mike

> 
> Am I the only one who immediately sees the trivial C transformation
> through which this function could lose a local variable and become 4
> lines shorter?
> 
> And this function got two Reviewed-by tags...
> 
> Thanks,
> 
> 	Ingo
>