From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753040Ab2LCIBa (ORCPT ); Mon, 3 Dec 2012 03:01:30 -0500 Received: from na3sys009aog107.obsmtp.com ([74.125.149.197]:52416 "EHLO na3sys009aog107.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750923Ab2LCIB3 (ORCPT ); Mon, 3 Dec 2012 03:01:29 -0500 From: Neil Zhang To: mingo@redhat.com, peterz@infradead.org Cc: cxie4@marvell.com, linux-kernel@vger.kernel.org, Neil Zhang Subject: [PATCH] sched/rt: don't enable runtime if already enabled Date: Mon, 3 Dec 2012 16:01:15 +0800 Message-Id: <1354521675-31245-1-git-send-email-zhangwm@marvell.com> X-Mailer: git-send-email 1.7.4.1 X-OriginalArrivalTime: 03 Dec 2012 08:01:19.0287 (UTC) FILETIME=[6096BC70:01CDD12C] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There are two paths will call __enable_runtime, they are enable_runtime and rq_online. Don't enable runtime again if it is already enabled. It can fix the following kernel BUG when do cpu hotplug while there are realtime threads running. [ 3347.091644] kernel BUG at kernel/sched/rt.c:687! [ 3347.091674] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM [ 3347.091674] Modules linked in: cidatattydev(O) gs_diag(O) diag(O) gs_modem(O) ccinetdev(O) cci_datastub(O) citty(O) msocke [ 3347.091705] CPU: 1 Tainted: G O (3.4.5+ #439) [ 3347.091735] PC is at __disable_runtime+0x1e4/0x240 [ 3347.091735] LR is at __disable_runtime+0x1dc/0x240 [ 3347.091735] pc : [] lr : [] psr: a0000093 [ 3347.091735] sp : e0061dc8 ip : c0807861 fp : c07a9740 [ 3347.091766] r10: c1a0b740 r9 : ffffffff r8 : fd050f80 [ 3347.091766] r7 : 00000002 r6 : 000003f8 r5 : c1a13740 r4 : c1a137d8 [ 3347.091766] r3 : ffffffff r2 : e0061dbc r1 : c06b11b6 r0 : 00000037 [ 3347.091796] Flags: NzCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel [ 3347.091796] Control: 10c53c7d Table: 21e5004a DAC: 00000015 Signed-off-by: Neil Zhang --- kernel/sched/rt.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 418feb0..6525e5b 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -722,9 +722,11 @@ static void __enable_runtime(struct rq *rq) raw_spin_lock(&rt_b->rt_runtime_lock); raw_spin_lock(&rt_rq->rt_runtime_lock); - rt_rq->rt_runtime = rt_b->rt_runtime; - rt_rq->rt_time = 0; - rt_rq->rt_throttled = 0; + if (rt_rq->rt_runtime == RUNTIME_INF) { + rt_rq->rt_runtime = rt_b->rt_runtime; + rt_rq->rt_time = 0; + rt_rq->rt_throttled = 0; + } raw_spin_unlock(&rt_rq->rt_runtime_lock); raw_spin_unlock(&rt_b->rt_runtime_lock); } -- 1.7.4.1