From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261654AbVDNXrC (ORCPT ); Thu, 14 Apr 2005 19:47:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261658AbVDNXrC (ORCPT ); Thu, 14 Apr 2005 19:47:02 -0400 Received: from mail.dif.dk ([193.138.115.101]:54658 "EHLO saerimmer.dif.dk") by vger.kernel.org with ESMTP id S261654AbVDNXqx (ORCPT ); Thu, 14 Apr 2005 19:46:53 -0400 Date: Fri, 15 Apr 2005 01:49:41 +0200 (CEST) From: Jesper Juhl To: Ingo Molnar Cc: Robert Love , Linus Torvalds , linux-kernel Subject: [PATCH] sched: fix never executed code due to expression always false Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org There are two expressions in kernel/sched.c that are always false since they test for <0 but the result of the expression is unsigned so they will never be less than zero. This patch implement the logic that I believe is intended without the signedness issue and without the nasty casts. patch is compile tested only Signed-off-by: Jesper Juhl --- sched.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) --- linux-2.6.12-rc2-mm3-orig/kernel/sched.c 2005-04-11 21:20:56.000000000 +0200 +++ linux-2.6.12-rc2-mm3/kernel/sched.c 2005-04-15 01:37:48.000000000 +0200 @@ -2697,9 +2697,10 @@ need_resched_nonpreemptible: schedstat_inc(rq, sched_cnt); now = sched_clock(); if (likely((long long)now - prev->timestamp < NS_MAX_SLEEP_AVG)) { - run_time = now - prev->timestamp; - if (unlikely((long long)now - prev->timestamp < 0)) + if (unlikely(prev->timestamp > now)) run_time = 0; + else + run_time = now - prev->timestamp; } else run_time = NS_MAX_SLEEP_AVG; @@ -2776,7 +2777,7 @@ go_idle: if (!rt_task(next) && next->activated > 0) { unsigned long long delta = now - next->timestamp; - if (unlikely((long long)now - next->timestamp < 0)) + if (unlikely(next->timestamp > now)) delta = 0; if (next->activated == 1)