linux-kernel - Re: [PATCH 5/5] x86/sysfs: Add PPIN in sysfs under cpu topology

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Date:   Thu, 20 Jan 2022 10:01:51 -0800
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Smita Koralahalli Channabasappa 
        <smita.koralahallichannabasappa@....com>,
        Wei Huang <wei.huang2@....com>,
        Tom Lendacky <thomas.lendacky@....com>, patches@...ts.linux.dev
Subject: Re: [PATCH 5/5] x86/sysfs: Add PPIN in sysfs under cpu topology

On Thu, Jan 20, 2022 at 02:35:51PM +0100, Borislav Petkov wrote:
> On Fri, Jan 07, 2022 at 02:54:42PM -0800, Tony Luck wrote:
> > +#define topology_ppin(cpu)			(cpu_data(cpu).ppin)
> 
> That looks unused. No need to add it.


It "looks" unused, But thanks to the obscurity of CPP macros using ## to
concatenate tokens it is needed.

This harmless looking line:

define_id_show_func(ppin, "%llx");

is transmogrified by this:

#define define_id_show_func(name, fmt)					\
static ssize_t name##_show(struct device *dev,				\
			   struct device_attribute *attr, char *buf)	\
{									\
	return sysfs_emit(buf, fmt "\n", topology_##name(dev->id));	\
                                         ^^^^^^^^^^^^^^^

                                         This becomes topology_ppin
}


Will fix the other stuff and rebase to latest so part 4 applies.

Thanks for the review.

-Tony