Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932508Ab0KSXUN (ORCPT ); Fri, 19 Nov 2010 18:20:13 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:51644 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932372Ab0KSXUL (ORCPT ); Fri, 19 Nov 2010 18:20:11 -0500 Date: Fri, 19 Nov 2010 15:19:49 -0800 From: Andrew Morton To: michalj@gmail.com, Geert Uytterhoeven , Rolf Eike Beer , linux-kernel@vger.kernel.org, Linux Fbdev development list Subject: Re: abs() vs. abs64() (was: Re: [PATCH] fbdev: fix nearest mode search) Message-Id: <20101119151949.b7e514f7.akpm@linux-foundation.org> In-Reply-To: <20101119150411.81092e94.akpm@linux-foundation.org> References: <20101119140721.33576c61.akpm@linux-foundation.org> <20101119222823.GA28797@quadria> <20101119150411.81092e94.akpm@linux-foundation.org> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.9; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1951 Lines: 52 On Fri, 19 Nov 2010 15:04:11 -0800 Andrew Morton wrote: > > Looks good to me. I posted essentially the same thing some 3 months ago > > (http://marc.info/?l=linux-kernel&m=128033094822201&w=2) but it then > > failed to get any traction. At any rate, I like your version better as > > it seems more readable. > > > > I spose we should document it. Does this look complete and accurate? > > --- a/include/linux/kernel.h~include-linux-kernelh-abs-fix-handling-of-32-bit-unsigneds-on-64-bit-fix > +++ a/include/linux/kernel.h > @@ -143,6 +143,13 @@ extern int _cond_resched(void); > > #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) > > +/* > + * abs() handles unsigned and signed longs, ints, shorts and chars. For long > + * types it returns a signed long. For int, short and char types it returns a > + * signed int. > + * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64() > + * for those. > + */ > #define abs(x) ({ \ > long ret; \ > if (sizeof(x) == sizeof(long)) { \ Well that was a load of bollocks. 2nd attempt: --- a/include/linux/kernel.h~include-linux-kernelh-abs-fix-handling-of-32-bit-unsigneds-on-64-bit-fix +++ a/include/linux/kernel.h @@ -143,6 +143,12 @@ extern int _cond_resched(void); #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) +/* + * abs() handles unsigned and signed longs, ints, shorts and chars. For all + * input types abs() returns a signed long. + * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64() + * for those. + */ #define abs(x) ({ \ long ret; \ if (sizeof(x) == sizeof(long)) { \ _ -- 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/