linux-kernel - Re: [PATCH] timer: Fix jiffies wrap behavior of round

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Message-ID: <51A6EF57.8020507@acm.org>
Date:	Thu, 30 May 2013 08:19:03 +0200
From:	Bart Van Assche <bvanassche@....org>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Arjan van de Ven <arjan@...radead.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Joe Perches <joe@...ches.com>
Subject: Re: [PATCH] timer: Fix jiffies wrap behavior of round_jiffies*()

On 05/30/13 01:01, Andrew Morton wrote:
> On Tue, 21 May 2013 20:43:50 +0200 Bart Van Assche <bart.vanassche@...il.com> wrote:
>
>> Make sure that the round_jiffies*() functions return a time that is
>> in the future when the jiffies counter is about to wrap.
>
> Actually "when the jiffies counter has recently wrapped".
>
> I assume this was found by inspection?

Hello Andrew,

You are correct, this was found via source code inspection. I started 
reviewing the round_jiffies*() implementation because I was chasing a 
bug in a kernel driver using one of these functions.

>> -		return original;
>> -	return j;
>> +	return time_is_after_jiffies(j) ? j : original;
>>   }
>
> Your email client mangles patches, btw.

Sorry. Will take more care in the future.

Bart.

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