From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF708C2BA83 for ; Wed, 12 Feb 2020 14:24:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C44402168B for ; Wed, 12 Feb 2020 14:24:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728294AbgBLOYW (ORCPT ); Wed, 12 Feb 2020 09:24:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:42764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727988AbgBLOYV (ORCPT ); Wed, 12 Feb 2020 09:24:21 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 276BD206D7; Wed, 12 Feb 2020 14:24:20 +0000 (UTC) Date: Wed, 12 Feb 2020 09:24:17 -0500 From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com Subject: Re: [PATCH 4/8] sched,rcu,tracing: Mark preempt_count_{add,sub}() notrace Message-ID: <20200212092417.04c3da8c@gandalf.local.home> In-Reply-To: <20200212094107.838108888@infradead.org> References: <20200212093210.468391728@infradead.org> <20200212094107.838108888@infradead.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 12 Feb 2020 10:32:14 +0100 Peter Zijlstra wrote: > Because of the requirement that no tracing happens until after we've > incremented preempt_count, see nmi_enter() / trace_rcu_enter(), mark > these functions as notrace. I actually depend on these function being traced. We do have "preempt_enable_notrace()" and "preempt_disable_notrace()" for places that shouldn't be traced. Can't we use those? (or simply __preempt_count_add()) in the nmi_enter() code instead? (perhaps create a preempt_count_add_notrace()). -- Steve > > Signed-off-by: Peter Zijlstra (Intel) > --- > kernel/sched/core.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3781,7 +3781,7 @@ static inline void preempt_latency_start > } > } > > -void preempt_count_add(int val) > +void notrace preempt_count_add(int val) > { > #ifdef CONFIG_DEBUG_PREEMPT > /* > @@ -3813,7 +3813,7 @@ static inline void preempt_latency_stop( > trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip()); > } > > -void preempt_count_sub(int val) > +void notrace preempt_count_sub(int val) > { > #ifdef CONFIG_DEBUG_PREEMPT > /* >