linux-kernel - Re: [PATCH 5/9] x86/nmi: Fix comment in unknown NMI handling

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Message-ID: <c042fc4c-061e-4cb5-af3b-0ad701850052@intel.com>
Date: Mon, 31 Mar 2025 22:28:20 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: "Huang, Kai" <kai.huang@...el.com>, "tglx@...utronix.de"
	<tglx@...utronix.de>, "mingo@...hat.com" <mingo@...hat.com>, "x86@...nel.org"
	<x86@...nel.org>
CC: "Nikula, Jani" <jani.nikula@...el.com>, "bp@...en8.de" <bp@...en8.de>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"peterz@...radead.org" <peterz@...radead.org>, "hpa@...or.com"
	<hpa@...or.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "kirill.shutemov@...ux.intel.com"
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	<jpoimboe@...nel.org>, "pmladek@...e.com" <pmladek@...e.com>, "xin@...or.com"
	<xin@...or.com>, "Luck, Tony" <tony.luck@...el.com>
Subject: Re: [PATCH 5/9] x86/nmi: Fix comment in unknown NMI handling

On 3/31/2025 5:17 PM, Huang, Kai wrote:
> On Thu, 2025-03-27 at 23:46 +0000, Mehta, Sohil wrote:
>> The comment in unknown NMI handling is incorrect and misleading. There
>> is no longer a restriction on having a single Unknown NMI handler. Also,
>> nmi_handle() does not use the 'b2b' parameter anymore.
>>
>> The changes that made the comment outdated are:
>>
>> commit 0d443b70cc92 ("x86/platform: Remove warning message for duplicate
>> NMI handlers")
>>
>> commit bf9f2ee28d47 ("x86/nmi: Remove the 'b2b' parameter from
>> nmi_handle()")
> 
> After some digging, IIUC, the 'b2b' parameter of the nmi_handle() was actually
> never used when it was originally added in the 
> 

You are right. The b2b parameter was never really used. The fixup patch
says the same thing as well.

	"x86/nmi: Remove the 'b2b' parameter from nmi_handle()

	It has never had any effect. Remove it for comprehensibility."



>   commit b227e23399dc ("x86, nmi: Add in logic to handle multiple events and
> unknown NMIs")
> 

It's probably okay even if we don't mention this directly in the
changelog. It is indirectly implied through the above fixup patch.

> .., so IIUC the comment was wrong when it was firstly added.  
> > The above commit to remove the 'b2b' seems just a fixup patch but it
didn't fix
> the comment.
> 

Yup, that's what I meant. The fixup patch should have fixed the comment
as well.

> Not sure whether it is worth to mention in the changelog.
> 

> 
> Anyway:
> 
> Reviewed-by: Kai Huang <kai.huang@...el.com>

Thanks!