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

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Message-ID: <20130412133846.GD2368@pd.tnic>
Date:	Fri, 12 Apr 2013 15:38:46 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Steven Rostedt <rostedt@...dmis.org>
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 Thu, Apr 11, 2013 at 02:33:34PM -0400, Steven Rostedt wrote:
> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
> index e8d8ad0..060e473 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce.c
> @@ -18,6 +18,7 @@
>  #include <linux/rcupdate.h>
>  #include <linux/kobject.h>
>  #include <linux/uaccess.h>
> +#include <linux/kthread.h>
>  #include <linux/kdebug.h>
>  #include <linux/kernel.h>
>  #include <linux/percpu.h>
> @@ -1308,6 +1309,61 @@ static void mce_do_trigger(struct work_struct *work)
>  
>  static DECLARE_WORK(mce_trigger_work, mce_do_trigger);
>  
> +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.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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