Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754258AbXFDLtK (ORCPT ); Mon, 4 Jun 2007 07:49:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753439AbXFDLs6 (ORCPT ); Mon, 4 Jun 2007 07:48:58 -0400 Received: from emailhub.stusta.mhn.de ([141.84.69.5]:53211 "EHLO mailhub.stusta.mhn.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753229AbXFDLs5 (ORCPT ); Mon, 4 Jun 2007 07:48:57 -0400 Date: Mon, 4 Jun 2007 13:49:00 +0200 From: Adrian Bunk To: Rolf Eike Beer Cc: linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , stable@kernel.org Subject: Re: [PATCH] Fix roundup_pow_of_two(1) Message-ID: <20070604114900.GS5500@stusta.de> References: <200705172356.57620.eike-kernel@sf-tec.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <200705172356.57620.eike-kernel@sf-tec.de> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1779 Lines: 51 On Thu, May 17, 2007 at 11:56:56PM +0200, Rolf Eike Beer wrote: > Fix roundup_pow_of_two(1) > > 1 is a power of two, therefore roundup_pow_of_two(1) should return 1. It does > in case the argument is a variable but in case it's a constant it behaves > wrong and returns 0. Probably nobody ever did it so this was never noticed. I'm not getting the problem. 2^0 = 1 > Signed-off-by: Rolf Eike Beer > > --- > commit 01ceeffac83011f0b5021013cc4abd1c4f291df5 > tree 7da59df51617d7cebd55e4361019181645a17e10 > parent ab35916f807eb4f2019a208e96cb0bddbb91dfc3 > author Rolf Eike Beer Thu, 17 May 2007 23:43:54 +0200 > committer Rolf Eike Beer Thu, 17 May 2007 23:43:54 +0200 > > include/linux/log2.h | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/include/linux/log2.h b/include/linux/log2.h > index 57e641e..1b8a2c1 100644 > --- a/include/linux/log2.h > +++ b/include/linux/log2.h > @@ -159,7 +159,7 @@ unsigned long __roundup_pow_of_two(unsigned long n) > #define roundup_pow_of_two(n) \ > ( \ > __builtin_constant_p(n) ? ( \ > - (n == 1) ? 0 : \ > + (n == 1) ? 1 : \ > (1UL << (ilog2((n) - 1) + 1)) \ > ) : \ > __roundup_pow_of_two(n) \ cu Adrian -- "Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/