linux-kernel - Re: [PATCH RT v2] x86/mce: Defer mce wakeups to threads for PREEMPT

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Date:	Fri, 12 Apr 2013 09:44:15 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	RT <linux-rt-users@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Clark Williams <clark@...hat.com>,
	John Kacur <jkacur@...hat.com>,
	Tony Luck <tony.luck@...el.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: Re: [PATCH RT v2] x86/mce: Defer mce wakeups to threads for
 PREEMPT_RT

On Fri, 2013-04-12 at 15:38 +0200, Borislav Petkov wrote:

> > +static void __mce_notify_work(void)
> > +{
> > +	/* Not more than two messages every minute */
> > +	static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2);
> > +
> > +	/* wake processes polling /dev/mcelog */
> > +	wake_up_interruptible(&mce_chrdev_wait);
> > +
> > +	/*
> > +	 * There is no risk of missing notifications because
> > +	 * work_pending is always cleared before the function is
> > +	 * executed.
> > +	 */
> 
> You must be using some tree != mainline because this comment is gone
> upstream and that whole second hunk below which moves it here doesn't
> apply.
> 

I forgot to state that I based this off of 3.6-rt, and will be
backporting it to 3.0-rt as that's the kernel that the bug was reported
on. But the problem still exists in mainline as well (for -rt).

-- Steve


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