From: Andrew Morton <akpm@osdl.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: willy@debian.org, bernie@develer.com, akpm@zip.com.au,
linux-kernel@vger.kernel.org
Subject: Re: do_div vs sector_t
Date: Fri, 11 Jul 2003 23:58:22 -0700 [thread overview]
Message-ID: <20030711235822.31dde2fc.akpm@osdl.org> (raw)
In-Reply-To: <20030712075202.A1327@infradead.org>
Christoph Hellwig <hch@infradead.org> wrote:
>
> On Fri, Jul 11, 2003 at 11:33:59PM +0100, Matthew Wilcox wrote:
> > aic->seek_mean = aic->seek_total + 128;
> > do_div(aic->seek_mean, aic->seek_samples);
> > }
> >
> > seek_mean is a sector_t so sometimes it's 64-bit on a 32-bit platform.
> > so we can't avoid calling do_div().
>
> That's why we have sector_div, never use do_div on a sector_t.
Thing is, the arith in there can overflow with 32-bit sector_t anyway, so
we need 64-bit quantities regardless of the CONFIG_LBD setting.
next prev parent reply other threads:[~2003-07-12 6:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-11 22:33 do_div vs sector_t Matthew Wilcox
2003-07-11 22:34 ` Andrew Morton
2003-07-11 22:42 ` Neil Brown
2003-07-12 0:14 ` do_div vs sector_t (patch) Nick Piggin
2003-07-12 6:52 ` do_div vs sector_t Christoph Hellwig
2003-07-12 6:58 ` Andrew Morton [this message]
2003-07-13 17:26 ` Richard Henderson
2003-07-13 17:39 ` Russell King
2003-07-13 19:14 ` Bernardo Innocenti
2003-07-13 20:04 ` Matthew Wilcox
2003-07-14 4:07 ` Peter Chubb
-- strict thread matches above, loose matches on Subject: below --
2003-07-13 18:40 linux
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