From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754256AbaCCJgb (ORCPT ); Mon, 3 Mar 2014 04:36:31 -0500 Received: from merlin.infradead.org ([205.233.59.134]:33480 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753512AbaCCJg3 (ORCPT ); Mon, 3 Mar 2014 04:36:29 -0500 Date: Mon, 3 Mar 2014 10:35:58 +0100 From: Peter Zijlstra To: Juri Lelli Cc: Kirill Tkhai , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , tkhai@yandex.ru Subject: Re: [PATCH]sched/core: Return possibility to set RT and DL classes back Message-ID: <20140303093558.GP27965@twins.programming.kicks-ass.net> References: <1393496657.3522.3.camel@tkhai> <1393584643.3522.5.camel@tkhai> <20140301191838.d15d03112b2598a671dac22c@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140301191838.d15d03112b2598a671dac22c@gmail.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 01, 2014 at 07:18:38PM +0100, Juri Lelli wrote: > From 73bae0ad978db6e75f492eea9adff12ec9d6d2a3 Mon Sep 17 00:00:00 2001 > From: Juri Lelli > Date: Sat, 1 Mar 2014 16:43:30 +0100 > Subject: [PATCH] sched/core: restore __setscheduler() behavior > > Commit c365c29 introduced __setscheduler_params(), that is now used > to only store a task's new scheduling parameters in the case it is > priority boosted. > > Before this change, __setscheduler() was in charge of changing tasks > normal_prio and prio, and the latter is used to actually perform > sched_class change. Unfortunately, the commit above broke this > behavior, causing tasks to remain in fair_sched_class. > > Restore the old behaviour setting normal_prio and prio to the right > values after the __setscheduler_params() call. Please also add a Fixes: tag when appropriate, and add to Cc all those two were involved with the original patch. Fixes: c365c292d059 ("sched: Consider pi boosting in setscheduler()") > Signed-off-by: Juri Lelli > --- > kernel/sched/core.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index ee8004c..04ae20d 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3206,6 +3206,13 @@ static void __setscheduler(struct rq *rq, struct task_struct *p, > { > __setscheduler_params(p, attr); > > + /* > + * Since we checked before with rt_mutex_check_prio(), > + * we don't have pi waiters or our top waiter has lower > + * priority (user space view) than what we got. > + */ > + p->prio = p->normal_prio = normal_prio(p); > + > if (dl_prio(p->prio)) > p->sched_class = &dl_sched_class; > else if (rt_prio(p->prio)) So there is one more caller of this: normalize_task() but since that is only used to force set all tasks to SCHED_NORMAL ignoring the PI stuff seems perfectly fine.