To: David Miller <davem@davemloft.net>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org, openib-general@openib.org,
       tom@opengridcomputing.com
Subject: Re: [PATCH] Avoid truncating to 'long' in ALIGN() macro
References: <adazmag5bk1.fsf@cisco.com>
	<20061124.220746.57445336.davem@davemloft.net>
	<adaodqv5e5l.fsf@cisco.com>
	<20061125.150500.14841768.davem@davemloft.net>
From: Roland Dreier <rdreier@cisco.com>
Date: Sat, 25 Nov 2006 15:09:38 -0800
In-Reply-To: <20061125.150500.14841768.davem@davemloft.net> (David Miller's message of "Sat, 25 Nov 2006 15:05:00 -0800 (PST)")
Message-ID: <adak61j5djh.fsf@cisco.com>
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 > You would need to also cast the constants with typeof() to.

Why?  I'm not much of a C language lawyer, but I would have thought
that in something like

	(x) + _a - 1

the "1" will be promoted to the type of the rest of the expression
without any explicit cast.  I tested the unsigned long/unsigned int
and u64/int cases of ALIGN(), and my macro with typeof() works for
both of those cases at least.

 > But yes, given the array sizing case in the neighbour code,
 > perhaps we can use your original patch for now.  Feel free
 > to push that to Linus.

akpm is CC'ed on this thread.  Andrew, are you going to pick this up?

Thanks,
  Roland
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