Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262431AbVESBFM (ORCPT ); Wed, 18 May 2005 21:05:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262437AbVESBE3 (ORCPT ); Wed, 18 May 2005 21:04:29 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:65262 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S262431AbVESBET (ORCPT ); Wed, 18 May 2005 21:04:19 -0400 Message-ID: <428BE5F9.6070100@mvista.com> Date: Wed, 18 May 2005 18:03:53 -0700 From: George Anzinger Reply-To: george@mvista.com Organization: MontaVista Software User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.6) Gecko/20050323 Fedora/1.7.6-1.3.2 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Coywolf Qi Hunt CC: akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [patch] time_after_eq fix References: <20050518224415.GA5768@lovecn.org> In-Reply-To: <20050518224415.GA5768@lovecn.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2466 Lines: 63 Coywolf Qi Hunt wrote: > Hello, > > The two macros time_after and time_after_eq were added to do wrapping > correctly, but only time_after does it the right way, time_after_eq has > been wrong since the very beginning(v2.1.127, 07-Nov-1998). Now this > patch fixes it. I may be especially dense today, but could you give an example where your change actually gives a result different from what exists? george -- > > And I don't agree with the the original code comment. I don't think this > is gcc's fault. If it is "a good compiler" or "a really good compiler", > trying to be smarter than human, it wouldn't still be a C compiler. > So I'd like it be removed. > > Signed-off-by: Coywolf Qi Hunt > --- > > jiffies.h | 6 ++---- > 1 files changed, 2 insertions(+), 4 deletions(-) > > diff -pruN 2.6.12-rc4-mm2/include/linux/jiffies.h 2.6.12-rc4-mm2-cy/include/linux/jiffies.h > --- 2.6.12-rc4-mm2/include/linux/jiffies.h 2005-03-03 17:12:13.000000000 +0800 > +++ 2.6.12-rc4-mm2-cy/include/linux/jiffies.h 2005-05-19 05:32:52.000000000 +0800 > @@ -102,9 +102,7 @@ static inline u64 get_jiffies_64(void) > * > * time_after(a,b) returns true if the time a is after time b. > * > - * Do this with "<0" and ">=0" to only test the sign of the result. A > - * good compiler would generate better code (and a really good compiler > - * wouldn't care). Gcc is currently neither. > + * Do this with "<0" and "<=0" to only test the sign of the result. > */ > #define time_after(a,b) \ > (typecheck(unsigned long, a) && \ > @@ -115,7 +113,7 @@ static inline u64 get_jiffies_64(void) > #define time_after_eq(a,b) \ > (typecheck(unsigned long, a) && \ > typecheck(unsigned long, b) && \ > - ((long)(a) - (long)(b) >= 0)) > + ((long)(b) - (long)(a) <= 0)) > #define time_before_eq(a,b) time_after_eq(b,a) > > /* > - > 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/ > -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ - 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/