From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934572AbdDGRsc (ORCPT ); Fri, 7 Apr 2017 13:48:32 -0400 Received: from mail.kernel.org ([198.145.29.136]:48722 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932905AbdDGRsY (ORCPT ); Fri, 7 Apr 2017 13:48:24 -0400 Date: Fri, 7 Apr 2017 13:48:19 -0400 From: Steven Rostedt To: Mathieu Desnoyers Cc: linux-kernel , Ingo Molnar , Andrew Morton , "Paul E. McKenney" Subject: [PATCH 7/5 v2] tracing: Make sure rcu_irq_enter() can work for trace_*_rcuidle() trace events Message-ID: <20170407134819.6b66b7de@gandalf.local.home> In-Reply-To: <1475342880.4473.1491585545139.JavaMail.zimbra@efficios.com> References: <20170407140106.051135969@goodmis.org> <20170407130615.2309b96d@gandalf.local.home> <1475342880.4473.1491585545139.JavaMail.zimbra@efficios.com> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" Stack tracing discovered that there's a small location inside the RCU infrastructure where 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. Link: http://lkml.kernel.org/r/20170405093207.404f8deb@gandalf.local.home Cc: Mathieu Desnoyers Signed-off-by: Steven Rostedt (VMware) --- Mathieu, is this better? (yeah, i left in functionable, because I like that word ;-) include/linux/tracepoint.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index f72fcfe..352f32a 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -151,7 +151,12 @@ extern void syscall_unregfunc(void); } while (0) #ifndef MODULE -#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ +#define TRACE_RCU_IRQ_ENTER_CHECK \ + if (WARN_ON_ONCE(rcu_irq_enter_disabled())) \ + return; \ + rcu_irq_enter_irqson() + +#define __DECLARE_TRACE_RCU(name, proto, args, cond, data_proto, data_args) \ static inline void trace_##name##_rcuidle(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ @@ -159,7 +164,7 @@ extern void syscall_unregfunc(void); TP_PROTO(data_proto), \ TP_ARGS(data_args), \ TP_CONDITION(cond), \ - rcu_irq_enter_irqson(), \ + PARAMS(TRACE_RCU_IRQ_ENTER_CHECK), \ rcu_irq_exit_irqson()); \ } #else -- 2.9.3