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 08FF6C35254 for ; Wed, 5 Feb 2020 13:14:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1806217F4 for ; Wed, 5 Feb 2020 13:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727970AbgBENOQ (ORCPT ); Wed, 5 Feb 2020 08:14:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:60144 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726822AbgBENOQ (ORCPT ); Wed, 5 Feb 2020 08:14:16 -0500 Received: from oasis.local.home (unknown [212.187.182.165]) (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 A1266217BA; Wed, 5 Feb 2020 13:14:13 +0000 (UTC) Date: Wed, 5 Feb 2020 08:14:09 -0500 From: Steven Rostedt To: "Paul E. McKenney" Cc: Joel Fernandes , Amol Grover , Ingo Molnar , linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, Madhuparna Bhowmik Subject: Re: [PATCH] tracing: Annotate ftrace_graph_hash pointer with __rcu Message-ID: <20200205081409.4550aa67@oasis.local.home> In-Reply-To: <20200205131110.GT2935@paulmck-ThinkPad-P72> References: <20200201072703.17330-1-frextrite@gmail.com> <20200203163301.GB85781@google.com> <20200204200116.479f0c60@oasis.local.home> <20200205131110.GT2935@paulmck-ThinkPad-P72> 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, 5 Feb 2020 05:11:10 -0800 "Paul E. McKenney" wrote: > I strongly recommend a comment stating why disabling preemption prevents > ftrace_graph_hash from going away. I see the synchronize_rcu() after > the rcu_assign_pointer() in ftrace_graph_release(), but I don't see > anything that waits on CPUs that RCU is not watching. > > Of course, event tracing -makes- RCU watch when needed, but if that > was set up, then lockdep would not have complained. > > So what am I missing? Keep looking in your INBOX and look at the patch I asked you to ack or complain about ;-) -- Steve