From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754868AbaISJWl (ORCPT ); Fri, 19 Sep 2014 05:22:41 -0400 Received: from service87.mimecast.com ([91.220.42.44]:40263 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751558AbaISJWj (ORCPT ); Fri, 19 Sep 2014 05:22:39 -0400 From: Juri Lelli To: peterz@infradead.org Cc: mingo@redhat.com, juri.lelli@gmail.com, raistlin@linux.it, michael@amarulasolutions.com, fchecconi@gmail.com, daniel.wagner@bmw-carit.de, vincent@legout.info, luca.abeni@unitn.it, linux-kernel@vger.kernel.org, Juri Lelli Subject: [PATCH 1/3] sched/deadline: clear dl_entity params when setscheduling to different class Date: Fri, 19 Sep 2014 10:22:39 +0100 Message-Id: <1411118561-26323-2-git-send-email-juri.lelli@arm.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1411118561-26323-1-git-send-email-juri.lelli@arm.com> References: <1411118561-26323-1-git-send-email-juri.lelli@arm.com> X-OriginalArrivalTime: 19 Sep 2014 09:22:35.0068 (UTC) FILETIME=[3F5A1FC0:01CFD3EB] X-MC-Unique: 114091910223703301 Content-Type: text/plain; charset=WINDOWS-1252 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id s8J9MwFA015345 When a task is using SCHED_DEADLINE and the user setschedules it to a different class its sched_dl_entity static parameters are not cleaned up. This causes a bug if the user sets it back to SCHED_DEADLINE with the same parameters again. The problem resides in the check we perform at the very beginning of dl_overflow(): if (new_bw == p->dl.dl_bw) return 0; This condition is met in the case depicted above, so the function returns and dl_b->total_bw is not updated (the p->dl.dl_bw is not added to it). After this, admission control is broken. This patch fixes the thing, properly clearing static parameters for a task that ceases to use SCHED_DEADLINE. Reported-by: Daniele Alessandrelli Reported-by: Daniel Wagner Reported-by: Vincent Legout Tested-by: Luca Abeni Signed-off-by: Juri Lelli Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Dario Faggioli Cc: Michael Trimarchi Cc: Fabio Checconi Cc: linux-kernel@vger.kernel.org --- kernel/sched/core.c | 19 +++++++++++++++---- kernel/sched/deadline.c | 2 ++ kernel/sched/sched.h | 3 +++ 3 files changed, 20 insertions(+), 4 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ec1a286..581a429 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1776,6 +1776,20 @@ int wake_up_state(struct task_struct *p, unsigned int state) } /* + * This function clears the sched_dl_entity static params. + */ +void __dl_clear_params(struct task_struct *p) +{ + struct sched_dl_entity *dl_se = &p->dl; + + dl_se->dl_runtime = 0; + dl_se->dl_deadline = 0; + dl_se->dl_period = 0; + dl_se->flags = 0; + dl_se->dl_bw = 0; +} + +/* * Perform scheduler related setup for a newly forked process p. * p is forked by current. * @@ -1799,10 +1813,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p) RB_CLEAR_NODE(&p->dl.rb_node); hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); - p->dl.dl_runtime = p->dl.runtime = 0; - p->dl.dl_deadline = p->dl.deadline = 0; - p->dl.dl_period = 0; - p->dl.flags = 0; + __dl_clear_params(p); INIT_LIST_HEAD(&p->rt.run_list); diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 255ce13..4a51b14 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1569,6 +1569,8 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p) if (hrtimer_active(&p->dl.dl_timer) && !dl_policy(p->policy)) hrtimer_try_to_cancel(&p->dl.dl_timer); + __dl_clear_params(p); + #ifdef CONFIG_SMP /* * Since this might be the only -deadline task on the rq, diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 579712f..4890484 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -126,6 +126,9 @@ struct rt_bandwidth { u64 rt_runtime; struct hrtimer rt_period_timer; }; + +void __dl_clear_params(struct task_struct *p); + /* * To keep the bandwidth of -deadline tasks and groups under control * we need some place where: -- 2.1.0