linux-kernel - Re: [PATCH] Provide u64 version of jiffies_to

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Message-ID: <4775D276.7040301@zytor.com>
Date:	Fri, 28 Dec 2007 20:52:06 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jonathan Lim <jlim@....com>
CC:	linux-kernel@...r.kernel.org, jlan@....com
Subject: Re: [PATCH] Provide u64 version of jiffies_to_usecs() in kernel/tsacct.c

Jonathan Lim wrote:
> It's possible that the values used in and returned from jiffies_to_usecs() are
> incorrect because of truncation when variables of type u64 are involved.  So a
> function specific to that type is used instead.

Much worse than that.  There are internal overflows in the conversions. 
See the patch I recently submitted to -mm.

	-hpa
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