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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 93771C2BA83 for ; Wed, 12 Feb 2020 14:32:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 72B5F2082F for ; Wed, 12 Feb 2020 14:32:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728174AbgBLOci (ORCPT ); Wed, 12 Feb 2020 09:32:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:46844 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727662AbgBLOci (ORCPT ); Wed, 12 Feb 2020 09:32:38 -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 547D8206D7; Wed, 12 Feb 2020 14:32:36 +0000 (UTC) Date: Wed, 12 Feb 2020 09:32:34 -0500 From: Steven Rostedt To: Will Deacon Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, james.morse@arm.com, catalin.marinas@arm.com, 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 0/8] tracing vs rcu vs nmi Message-ID: <20200212093235.2be06208@gandalf.local.home> In-Reply-To: <20200212105646.GA4017@willie-the-truck> References: <20200212093210.468391728@infradead.org> <20200212100106.GA14914@hirez.programming.kicks-ass.net> <20200212105646.GA4017@willie-the-truck> 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 10:56:46 +0000 Will Deacon wrote: > Hmm, so looks like we need to spinkle some 'notrace' annotations around > these. Are there are scenarios where you would want NOKPROBE_SYMBOL() but > *not* 'notrace'? We've already got the former for the debug exception > handlers and we probably (?) want it for the SDEI stuff too... Note, function tracing has a lot of recursion detection, and when something registers with the function tracer it needs to state if it can be called when rcu is not watching, or it wont be called then. And yes, there's plenty of places that we have "nokprobe" but allow tracing. I've been trying to get rid of notrace around the kernel, not add more. -- Steve