linux-kernel - Re: [patch v2 19/38] x86/cpu: Provide debug interface

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Message-ID: <ef3e63b2-d73b-b03f-2f5e-df456d756a63@intel.com>
Date:   Fri, 28 Jul 2023 16:57:54 -0700
From:   Sohil Mehta <sohil.mehta@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
CC:     <x86@...nel.org>, Tom Lendacky <thomas.lendacky@....com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Dick Kennedy <dick.kennedy@...adcom.com>,
        James Smart <james.smart@...adcom.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        <linux-scsi@...r.kernel.org>, Guenter Roeck <linux@...ck-us.net>,
        <linux-hwmon@...r.kernel.org>, "Jean Delvare" <jdelvare@...e.com>,
        Huang Rui <ray.huang@....com>, Juergen Gross <jgross@...e.com>,
        Steve Wahl <steve.wahl@....com>,
        Mike Travis <mike.travis@....com>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        "Russ Anderson" <russ.anderson@....com>
Subject: Re: [patch v2 19/38] x86/cpu: Provide debug interface

> +++ b/arch/x86/kernel/cpu/debugfs.c
> @@ -0,0 +1,58 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/debugfs.h>
> +
> +#include <asm/apic.h>
> +#include <asm/processor.h>
> +

I ran checkpatch through the patches and it lists a bunch of errors and
warnings. Most of them are due to issues in the existing code which is
probably not worth fixing.

However, I found a couple of recommendations which might be of interest.

1) Using linux headers instead of the asm ones. Namely,

> Consider using #include <linux/processor.h> instead of <asm/processor.h>
> Consider using #include <linux/topology.h> instead of <asm/topology.h>
> Consider using #include <linux/smp.h> instead of <asm/smp.h>

2) Macros with multiple statements should be enclosed in a do - while loop

>From patch 20/38:
> +#define cpuid_subleaf(leaf, subleaf, regs)		\
> +	BUILD_BUG_ON(sizeof(*(regs)) != 16);		\
> +	__cpuid_read(leaf, subleaf, (u32 *)(regs))


I am wondering if either of them matter?


> +static __init int cpu_init_debugfs(void)
> +{
> +	struct dentry *dir, *base = debugfs_create_dir("topo", arch_debugfs_dir);
> +	unsigned long id;
> +	char name [10];
> +

Excess space after name and before the square bracket can be avoided.


Sohil