linux-kernel - Re: [PATCH 3.4 098/107] kernel/watchdog.c: touch_nmi_watchdog should only touch local cpu not every one

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Date:	Thu, 17 Mar 2016 09:20:24 +0800
From:	Zefan Li <lizefan@...wei.com>
To:	Don Zickus <dzickus@...hat.com>, <lizf@...nel.org>
CC:	<stable@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Ben Zhang <benzh@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 3.4 098/107] kernel/watchdog.c: touch_nmi_watchdog should
 only touch local cpu not every one

>> diff --git a/kernel/watchdog.c b/kernel/watchdog.c
>> index 991aa93..7527c8c 100644
>> --- a/kernel/watchdog.c
>> +++ b/kernel/watchdog.c
>> @@ -162,6 +162,14 @@ void touch_nmi_watchdog(void)
>>  				per_cpu(watchdog_nmi_touch, cpu) = true;
>>  		}
>>  	}
> 
> The above for-loop was to be replaced by the non-for-loop below.
> 
> The above for-loop is the problem this patch was solving, so keeping it
> around does not solve anything.  :-)
> 

OOps, my fault. I'll remove this for-loop. Thanks for your review!

> 
>> +	/*
>> +	 * 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);
> 
> Cheers,
> Don
> .
>