From: "Ray Lee" <ray-lk@madrabbit.org>
To: "Julia Lawall" <julia@diku.dk>
Cc: hpa@zytor.com, autofs@linux.kernel.org,
linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH 1/4] fs/autofs: Use time_before, time_before_eq, etc.
Date: Wed, 26 Dec 2007 11:58:56 -0800 [thread overview]
Message-ID: <2c0942db0712261158q34cddebeifceef6ceda683320@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.58.0712261621000.1185@pc-041.diku.dk>
On Dec 26, 2007 7:21 AM, Julia Lawall <julia@diku.dk> wrote:
> - if (jiffies - ent->last_usage < timeout)
> + if (time_before(jiffies, ent->last_usage + timeout))
I don't think this is a safe change? subtraction is always safe (if
you think about it as 'distance'), addition isn't always safe unless
you know the range. The time_before macro will expand that out to
(effectively):
if ( (long)(ent->last_usage + timeout) - (long)(jiffies) < 0 )
which seems to introduce an overflow condition in the first term.
Dunno, I may be wrong (happens often), but at the very least what
you've transformed it into is no longer obviously correct, and so it's
not a great change.
next prev parent reply other threads:[~2007-12-26 19:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-26 15:21 Julia Lawall
2007-12-26 17:48 ` H. Peter Anvin
2007-12-26 19:19 ` Julia Lawall
2007-12-26 19:58 ` Ray Lee [this message]
2007-12-26 20:45 ` H. Peter Anvin
2007-12-27 7:08 ` Julia Lawall
2007-12-28 1:39 ` YOSHIFUJI Hideaki / 吉藤英明
2007-12-28 4:34 ` [autofs] " Ian Kent
2007-12-28 9:27 ` Julia Lawall
2007-12-28 14:21 ` [autofs] " Fabio Olive Leite
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