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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 6A8F0C35247 for ; Wed, 5 Feb 2020 22:30:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 432662072B for ; Wed, 5 Feb 2020 22:30:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727109AbgBEWar (ORCPT ); Wed, 5 Feb 2020 17:30:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:48490 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727358AbgBEWar (ORCPT ); Wed, 5 Feb 2020 17:30:47 -0500 Received: from oasis.local.home (unknown [81.144.254.34]) (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 DDDBA2072B; Wed, 5 Feb 2020 22:25:33 +0000 (UTC) Date: Wed, 5 Feb 2020 17:25:29 -0500 From: Steven Rostedt To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, Ingo Molnar , paulmck@kernel.org, frextrite@gmail.com, rcu@vger.kernel.org, madhuparnabhowmik04@gmail.com Subject: Re: [PATCH] kernel/trace: Use rcu_assign_pointer() for setting fgraph hash pointers Message-ID: <20200205172529.4282a0d1@oasis.local.home> In-Reply-To: <20200205221808.54576-1-joel@joelfernandes.org> References: <20200205221808.54576-1-joel@joelfernandes.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: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Wed, 5 Feb 2020 17:18:08 -0500 "Joel Fernandes (Google)" wrote: > set_ftrace_early_graph() sets pointers without any explicit > release-barriers. Let us use rcu_assign_pointer() to ensure the same. > > Note that ftrace_early_graph() calls ftrace_graph_set_hash() which does > do mutex_unlock(&ftrace_lock); which should imply a release barrier. > However it is better to not depend on it and just use > rcu_assign_pointer() which should also avoid sparse errors in the > future. This is going to have to wait for the next merge window, as I'm already *very* late, and I've pushed the limit to what I will add at this time frame. -- Steve