From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754844AbaDMNsb (ORCPT ); Sun, 13 Apr 2014 09:48:31 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.232]:26139 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754492AbaDMNsa convert rfc822-to-8bit (ORCPT ); Sun, 13 Apr 2014 09:48:30 -0400 Date: Sun, 13 Apr 2014 09:48:28 -0400 From: Steven Rostedt To: Mike Galbraith Cc: Peter Zijlstra , Ingo Molnar , LKML Subject: Re: [PATCH] sched/cpupri: fix cpupri_find() for high priority tasks Message-ID: <20140413094828.081e844e@gandalf.local.home> In-Reply-To: <20140413094023.47c762fd@gandalf.local.home> References: <1397015410.5212.13.camel@marge.simpson.net> <20140413094023.47c762fd@gandalf.local.home> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.22; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT X-RR-Connecting-IP: 107.14.168.130:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Actually, since task_pri is calculated from convert_prio() that check should never be hit. But, I'm paranoid, and instead of dropping the check, we can do the same as what cpupri_set() does. Which is to BUG. -- Steve >>From aac271901d6ef5ad19c52f166bf130ad27515b5f Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Sun, 13 Apr 2014 09:34:53 -0400 Subject: [PATCH] sched: Use CPUPRI_NR_PRIORITIES instead of MAX_RT_PRIO in cpupri check The check at the beginning of cpupri_find() makes sure that the task_pri variable does not exceed the cp->pri_to_cpu array length. But that length is CPUPRI_NR_PRIORITIES not MAX_RT_PRIO, where it will miss the last two priorities in that array. As task_pri is computed from convert_prio() which should never be bigger than CPUPRI_NR_PRIORITIES, if the check should cause a panic if it is hit. Link: http://lkml.kernel.org/r/1397015410.5212.13.camel@marge.simpson.net Cc: stable@vger.kernel.org Reported-by: Mike Galbraith Signed-off-by: Steven Rostedt --- kernel/sched/cpupri.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c index 8b836b3..3031bac 100644 --- a/kernel/sched/cpupri.c +++ b/kernel/sched/cpupri.c @@ -70,8 +70,7 @@ int cpupri_find(struct cpupri *cp, struct task_struct *p, int idx = 0; int task_pri = convert_prio(p->prio); - if (task_pri >= MAX_RT_PRIO) - return 0; + BUG_ON(task_pri >= CPUPRI_NR_PRIORITIES); for (idx = 0; idx < task_pri; idx++) { struct cpupri_vec *vec = &cp->pri_to_cpu[idx]; -- 1.8.1.4