linux-kernel - Re: [PATCH v10 2/3] watchdog: add watchdog

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Date:	Thu, 30 Apr 2015 16:09:52 -0400
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Don Zickus <dzickus@...hat.com>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrew Jones <drjones@...hat.com>,
	chai wen <chaiw.fnst@...fujitsu.com>,
	Ulrich Obergfell <uobergfe@...hat.com>,
	Fabian Frederick <fabf@...net.be>,
	Aaron Tomlin <atomlin@...hat.com>,
	Ben Zhang <benzh@...omium.org>,
	Christoph Lameter <cl@...ux.com>,
	Gilad Ben-Yossef <gilad@...yossef.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	<linux-kernel@...r.kernel.org>, Jonathan Corbet <corbet@....net>,
	<linux-doc@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v10 2/3] watchdog: add watchdog_cpumask sysctl to assist
 nohz

On 04/30/2015 04:00 PM, Don Zickus wrote:
> On Thu, Apr 30, 2015 at 03:39:25PM -0400, Chris Metcalf wrote:
>>   		if (err)
>>   			pr_err("Failed to create watchdog threads, disabled\n");
>> +		else {
>> +			if (smpboot_update_cpumask_percpu_thread(
>> +				    &watchdog_threads, &watchdog_cpumask))
>> +				pr_err("Failed to set cpumask for watchdog threads\n");
> Stupid nitpick, this error message tells us the 'watchdog' threads caused
> the cpumask failure, but ....
>
>> +			/*
>> +			 * Failure would be due to being unable to allocate
>> +			 * a temporary cpumask, so we are likely not in a
>> +			 * position to do much else to make things better.
>> +			 */
>> +			if (smpboot_update_cpumask_percpu_thread(
>> +				    &watchdog_threads, &watchdog_cpumask) != 0)
>> +				pr_err("cpumask update failed\n");
> This one does not. :-(  If there is a respin, I would suggest copying the
> above message down here.

There is that "#define pr_fmt(fmt)" at the top of the file that prefixes
all the messages with "NMI watchdog: ", though.  I think that's
sufficient to make it clear what the second message is about.
(The first message I wrote the way I did to be parallel with the
message just before it, if the thread creation failed.)

I could tweak the messages but I think they're reasonable given the
prefix.  What do you think?

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

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