From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752907AbaCLKLV (ORCPT ); Wed, 12 Mar 2014 06:11:21 -0400 Received: from terminus.zytor.com ([198.137.202.10]:48929 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751843AbaCLKLR (ORCPT ); Wed, 12 Mar 2014 06:11:17 -0400 Date: Wed, 12 Mar 2014 03:10:19 -0700 From: tip-bot for Steven Rostedt Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de, bigeasy@linutronix.de, juri.lelli@gmail.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de, bigeasy@linutronix.de, juri.lelli@gmail.com In-Reply-To: <20140306120438.638bfe94@gandalf.local.home> References: <20140306120438.638bfe94@gandalf.local.home> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Fix broken setscheduler() Git-Commit-ID: 383afd0971538b3d77532a56404b24cfe967b5dd X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 383afd0971538b3d77532a56404b24cfe967b5dd Gitweb: http://git.kernel.org/tip/383afd0971538b3d77532a56404b24cfe967b5dd Author: Steven Rostedt AuthorDate: Tue, 11 Mar 2014 19:24:20 -0400 Committer: Ingo Molnar CommitDate: Wed, 12 Mar 2014 10:48:59 +0100 sched: Fix broken setscheduler() I decided to run my tests on linux-next, and my wakeup_rt tracer was broken. After running a bisect, I found that the problem commit was: linux-next commit c365c292d059 "sched: Consider pi boosting in setscheduler()" And the reason the wake_rt tracer test was failing, was because it had no RT task to trace. I first noticed this when running with sched_switch event and saw that my RT task still had normal SCHED_OTHER priority. Looking at the problem commit, I found: - p->normal_prio = normal_prio(p); - p->prio = rt_mutex_getprio(p); With no + p->normal_prio = normal_prio(p); + p->prio = rt_mutex_getprio(p); Reading what the commit is suppose to do, I realize that the p->prio can't be set if the task is boosted with a higher prio, but the p->normal_prio still needs to be set regardless, otherwise, when the task is deboosted, it wont get the new priority. The p->prio has to be set before "check_class_changed()" is called, otherwise the class wont be changed. Also added fix to newprio to include a check for deadline policy that was missing. This change was suggested by Juri Lelli. Signed-off-by: Steven Rostedt Cc: SebastianAndrzej Siewior Cc: Juri Lelli Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140306120438.638bfe94@gandalf.local.home Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9e126a2..ae365aa 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3195,6 +3195,7 @@ static void __setscheduler_params(struct task_struct *p, * getparam()/getattr() don't report silly values for !rt tasks. */ p->rt_priority = attr->sched_priority; + p->normal_prio = normal_prio(p); set_load_weight(p); } @@ -3204,6 +3205,12 @@ static void __setscheduler(struct rq *rq, struct task_struct *p, { __setscheduler_params(p, attr); + /* + * If we get here, there was no pi waiters boosting the + * task. It is safe to use the normal prio. + */ + p->prio = normal_prio(p); + if (dl_prio(p->prio)) p->sched_class = &dl_sched_class; else if (rt_prio(p->prio)) @@ -3262,7 +3269,8 @@ static int __sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, bool user) { - int newprio = MAX_RT_PRIO - 1 - attr->sched_priority; + int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : + MAX_RT_PRIO - 1 - attr->sched_priority; int retval, oldprio, oldpolicy = -1, on_rq, running; int policy = attr->sched_policy; unsigned long flags;