linux-kernel - Re: [PATCH] watchdog: hpwdt: Remove spinlock acquire and BIOS calls from NMI context

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Message-ID: <20180215174444.GA25970@anatevka.americas.hpqcorp.net>
Date:   Thu, 15 Feb 2018 10:44:44 -0700
From:   Jerry Hoemann <jerry.hoemann@....com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Borislav Petkov <bp@...en8.de>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave@...1.net>, hpa@...or.com, tglx@...utronix.de,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        dwmw@...zon.co.uk, linux-tip-commits@...r.kernel.org,
        Arjan van de Ven <arjan@...radead.org>,
        linux-watchdog@...r.kernel.org
Subject: Re: [PATCH] watchdog: hpwdt: Remove spinlock acquire and BIOS calls
 from NMI context

On Thu, Feb 15, 2018 at 12:17:04AM +0100, Ingo Molnar wrote:
> 
> * Jerry Hoemann <jerry.hoemann@....com> wrote:
> 
> > 
> > Ingo,
> > 
> > I have a patch set under review that brings hpwdt into compliance
> > with the watchdog core.
> > 
> > One of the changes removes the callback into firmware in hpwdt_pretimeout
> > and its associated spinlock.
> > 
> > https://lkml.org/lkml/2018/2/12/30
> 
>  drivers/watchdog/hpwdt.c | 490 +----------------------------------------------
>  1 file changed, 8 insertions(+), 482 deletions(-)
> 
> Very nice, and this should solve all the NMI handling complications!
> 
> > I will add you to the CC list of the next version of the set.
> 
> Thanks!
> 
> 	Ingo


Ingo,

Is your desire to remove of the firmware callback/spinlock in hpwdt_pretimeout
related to David Woodhouse patch set:

	https://lkml.org/lkml/2018/2/14/305  ?

Which I think are to mitigate performance issues resulting from the
changes to address the specter/meltdown?

Any there other changes to hpwdt needed related to this work?

Thanks

Jerry

-- 

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Jerry Hoemann                  Software Engineer   Hewlett Packard Enterprise
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