From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162187AbcFGUVv (ORCPT ); Tue, 7 Jun 2016 16:21:51 -0400 Received: from merlin.infradead.org ([205.233.59.134]:56952 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422963AbcFGUTf (ORCPT ); Tue, 7 Jun 2016 16:19:35 -0400 Message-Id: <20160607200215.788266764@infradead.org> User-Agent: quilt/0.63-1 Date: Tue, 07 Jun 2016 21:56:38 +0200 From: Peter Zijlstra To: mingo@kernel.org, tglx@linutronix.de, juri.lelli@arm.com, rostedt@goodmis.org, xlpang@redhat.com Cc: linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, jdesfossez@efficios.com, bristot@redhat.com, peterz@infradead.org, Ingo Molnar Subject: [RFC][PATCH 3/8] sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update References: <20160607195635.710022345@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=xunlei_pang-sched_deadline_rtmutex-don_t_miss_the_dl_runtime_dl_period_update.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xunlei Pang Currently dl tasks will actually return at the very beginning of rt_mutex_adjust_prio_chain() in !detect_deadlock cases: if (waiter->prio == task->prio) { if (!detect_deadlock) goto out_unlock_pi; // out here else requeue = false; } As the deadline value of blocked deadline tasks(waiters) without changing their sched_class(thus prio doesn't change) never changes, this seems reasonable, but it actually misses the chance of updating rt_mutex_waiter's "dl_runtime(period)_copy" if a waiter updates its deadline parameters(dl_runtime, dl_period) or boosted waiter changes to !deadline class. Thus, force deadline task not out by adding the !dl_prio() condition. [peterz: I should introduce more task state comparators like rt_mutex_waiter_less, all PI prio comparisons already have this DL exception, except this one] Cc: Steven Rostedt Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Juri Lelli Signed-off-by: Xunlei Pang Signed-off-by: Peter Zijlstra (Intel) Link: http://lkml.kernel.org/r/1460633827-345-7-git-send-email-xlpang@redhat.com --- kernel/locking/rtmutex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -488,7 +488,7 @@ static int rt_mutex_adjust_prio_chain(st * enabled we continue, but stop the requeueing in the chain * walk. */ - if (waiter->prio == task->prio) { + if (waiter->prio == task->prio && !dl_task(task)) { if (!detect_deadlock) goto out_unlock_pi; else