Received: by 2002:a25:1506:0:0:0:0:0 with SMTP id 6csp267076ybv; Wed, 5 Feb 2020 05:17:28 -0800 (PST) X-Google-Smtp-Source: APXvYqz/aXaHtFWpBPpgnXs5cOEg1dfci3aoeaXRRExbgC7GnU9ztKprEap3ZRaIAYWAPCsoo0fA X-Received: by 2002:aca:f354:: with SMTP id r81mr2679231oih.90.1580908648608; Wed, 05 Feb 2020 05:17:28 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1580908648; cv=none; d=google.com; s=arc-20160816; b=fH+Pe9cPfKX6U0RmWj69dhOFDDtMflGLzyslOIYoASahdAps+AXR655HkNQ26CIgfv UUD0piVUe46BFym4nIU15FBYI7mQyPX6vkZYiA54QfooPELUbEFORNsjGLAG5l6PGPSp 42uE1iNFqpPagauyWzh85N6rQyedex9B/XZ5n1hdtTelMJq5kEtuw88f7/mLvEi8Dwn/ idPHrpwwIN5n2Evn3+bXbcrSr5Jcfj6jLf1C2S/lY0UID+L0YaVB4QVFC1v/E3qkJWDo Om3hVgVwpXask/adanSBDE3yn6bhy6cgdGYnhCBdjIfSRmWjAUD+s9ClVu/0h3hDE/aC UWCQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:subject:cc:to:from:date; bh=o2mC2jzgLcKhKwp+4hpfABmjdKd9YykJVoPJqj8tSD4=; b=AZeNXYXnXuYPnbjFShYOgqNbMECcU+am8hmfVpnfjX+bEtyXpw/51rSvr96ELwiXGD KkQ0SkKZ4jpiVwCXwQlthy7j607By+cPhMK7MthK/PxYyKgg2JI87t/ZnhEojdJoT43G qsGHR1sMsBPv+BCy4AVcrxxM9RCySgBqYCSjbVQX043/fbh6tXLg4rhIgMbqG2ky7df5 WoDgFx9fKz9z020tmeitzEoxZp3pARrriU0rr59inWdzfSCvVd0xXFDVkbOFTvQiw2dA 0R+ZtsGmQBxsCwgZD+8oel+G2Vwk/D77m4SFIBKeijZUMjFk0iiMGvXeP/qhEudqhSeH f7WQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id k10si13892477otn.323.2020.02.05.05.17.13; Wed, 05 Feb 2020 05:17:28 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727458AbgBENOQ (ORCPT + 99 others); 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