linux-kernel - Re: [PATCH] watchdog: touch_nmi_watchdog should only touch local cpu not every one

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Date:	Fri, 5 Nov 2010 15:51:18 +0200
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Don Zickus <dzickus@...hat.com>
Cc:	fweisbec@...il.com, Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>, akpm@...ux-foundation.org,
	sergey.senozhatsky@...il.com
Subject: Re: [PATCH] watchdog:  touch_nmi_watchdog should only touch local
 cpu not every one

On (11/04/10 21:18), Don Zickus wrote:
>  void touch_nmi_watchdog(void)
>  {
> +	/*
> +	 * Using __raw here because some code paths have
> +	 * preemption enabled.  If preemption is enabled
> +	 * then interrupts should be enabled too, in which
> +	 * case we shouldn't have to worry about the watchdog
> +	 * going off.
> +	 */
> +	__raw_get_cpu_var(watchdog_nmi_touch) = true;
> +
> +	touch_softlockup_watchdog();
> +}
> +EXPORT_SYMBOL(touch_nmi_watchdog);
> +
> +void touch_all_nmi_watchdogs(void)
> +{
>  	if (watchdog_enabled) {
>  		unsigned cpu;
>  
> @@ -151,7 +166,7 @@ void touch_nmi_watchdog(void)
>  	}
>  	touch_softlockup_watchdog();
>  }
> -EXPORT_SYMBOL(touch_nmi_watchdog);
> +EXPORT_SYMBOL(touch_all_nmi_watchdogs);
>  

Hello,
Seems like no one is actually calling touch_all_nmi_watchdogs, as for now. 
Right?


Minor nit

	touch_all_nmi_watchdogs:
	...
	for_each_present_cpu(cpu) {
		if (per_cpu(watchdog_nmi_touch, cpu) != true)
			per_cpu(watchdog_nmi_touch, cpu) = true;
	}


which is, I belive, could be simplified to 
	for_each_present_cpu(cpu) {
		per_cpu(watchdog_nmi_touch, cpu) = true;
	}



	Sergey

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