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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DEB61C433EF for ; Wed, 20 Apr 2022 18:43:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351004AbiDTSqC (ORCPT ); Wed, 20 Apr 2022 14:46:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238461AbiDTSqA (ORCPT ); Wed, 20 Apr 2022 14:46:00 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0F21A419A3; Wed, 20 Apr 2022 11:43:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 8226BB8214A; Wed, 20 Apr 2022 18:43:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C62ADC385A0; Wed, 20 Apr 2022 18:43:10 +0000 (UTC) Date: Wed, 20 Apr 2022 14:43:09 -0400 From: Steven Rostedt To: "Paul E. McKenney" Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH rcu 1/2] docs: Add documentation for rude and trace RCU flavors Message-ID: <20220420144309.69c6b8d1@gandalf.local.home> In-Reply-To: <20220420183726.GJ4285@paulmck-ThinkPad-P17-Gen-1> References: <20220418225004.GA3944767@paulmck-ThinkPad-P17-Gen-1> <20220418225033.3944860-1-paulmck@kernel.org> <20220420113231.6d3202e4@gandalf.local.home> <20220420161319.GD4285@paulmck-ThinkPad-P17-Gen-1> <20220420121906.13752d3e@gandalf.local.home> <20220420164847.GG4285@paulmck-ThinkPad-P17-Gen-1> <20220420140226.32a10ece@gandalf.local.home> <20220420183726.GJ4285@paulmck-ThinkPad-P17-Gen-1> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Apr 2022 11:37:26 -0700 "Paul E. McKenney" wrote: > The original purpose of RCU Tasks Rude was to deal with the idle tasks, > given that RCU Tasks dealt only with the non-idle tasks. > > Or is there a trick that I missed? It use to be that ftrace trampolines could be called from all sorts of locations until Peter introduced the "noinstr" annotation that causes objtool to fail to build when tracing happens there. If that prevents ftrace from happening in that idle case where RCU tasks can not handle it, then it may be that we can simply switch ftrace to the RCU tasks and get rid of rude. ? -- Steve