From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934478AbdDGRP6 (ORCPT ); Fri, 7 Apr 2017 13:15:58 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51239 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933961AbdDGRPt (ORCPT ); Fri, 7 Apr 2017 13:15:49 -0400 Date: Fri, 7 Apr 2017 10:15:45 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Mathieu Desnoyers Subject: Re: [PATCH 7/5] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events Reply-To: paulmck@linux.vnet.ibm.com References: <20170407140106.051135969@goodmis.org> <20170407130615.2309b96d@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170407130615.2309b96d@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 17040717-0048-0000-0000-00000150B1ED X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006894; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00844357; UDB=6.00416200; IPR=6.00622654; BA=6.00005275; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014953; XFM=3.00000013; UTC=2017-04-07 17:15:47 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17040717-0049-0000-0000-00004051CD36 Message-Id: <20170407171545.GB1600@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-04-07_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1702020001 definitions=main-1704070140 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 07, 2017 at 01:06:15PM -0400, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > Stack tracing discovered that there's a small location inside the RCU > infrastructure that calling rcu_irq_enter() does not work. As trace events > use rcu_irq_enter() it must make sure that it is functionable. A check > against rcu_irq_enter_disabled() is added with a WARN_ON_ONCE() as no trace > event should ever be used in that part of RCU. If the warning is triggered, > then the trace event is ignored. > > Cc: Mathieu Desnoyers > Signed-off-by: Steven Rostedt (VMware) Acked-by: Paul E. McKenney > --- > include/linux/tracepoint.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > index f72fcfe..8baef96 100644 > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -159,6 +159,8 @@ extern void syscall_unregfunc(void); > TP_PROTO(data_proto), \ > TP_ARGS(data_args), \ > TP_CONDITION(cond), \ > + if (WARN_ON_ONCE(rcu_irq_enter_disabled())) \ > + return; \ > rcu_irq_enter_irqson(), \ > rcu_irq_exit_irqson()); \ > } > -- > 2.9.3 >