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Date: Sat, 21 Apr 2007 14:06:22 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "John Anthony Kazos Jr." <jakj@j-a-k-j.com>,
       James Bottomley <James.Bottomley@SteelEye.com>,
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       linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
       trivial@kernel.org
Subject: Re: [PATCH] utilities: add helper functions for safe 64-bit integer
 operations as 32-bit halves
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On Sat, 21 Apr 2007 22:01:47 +0100 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> > > +#define lower_32_bits(n) (sizeof(n) == 8 ? (u32)(n) : (n))
> > 
> > n&0xffffffff would be simpler.
> > 
> > Do we actually have any call for this?
> 
> The only case for all of this we care about is sector_t, which is one
> type, with specific properties (eg always being positive). The rest is
> over-engineering. Call it sector_upper32() do it the simple way and stop
> trying to solve a problem we don't have

James said we have the same problem with dma_addr_t.