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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 27997C433DF for ; Fri, 12 Jun 2020 09:27:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 090192068E for ; Fri, 12 Jun 2020 09:27:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726482AbgFLJ1j (ORCPT ); Fri, 12 Jun 2020 05:27:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37566 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726335AbgFLJ1i (ORCPT ); Fri, 12 Jun 2020 05:27:38 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC9BCC03E96F; Fri, 12 Jun 2020 02:27:38 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jjfy6-0000uH-JW; Fri, 12 Jun 2020 11:27:22 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 06D73100F5A; Fri, 12 Jun 2020 11:27:22 +0200 (CEST) From: Thomas Gleixner To: paulmck@kernel.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org Cc: luto@kernel.org, x86@kernel.org, frederic@kernel.org, rostedt@goodmis.org, joel@joelfernandes.org, mathieu.desnoyers@efficios.com, will@kernel.org, peterz@infradead.org Subject: Re: [PATCH RFC] x86/entry: Ask RCU if it needs rcu_irq_{enter,exit}() In-Reply-To: <20200611235305.GA32342@paulmck-ThinkPad-P72> References: <20200611235305.GA32342@paulmck-ThinkPad-P72> Date: Fri, 12 Jun 2020 11:27:21 +0200 Message-ID: <87ftb0d47a.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Paul E. McKenney" writes: > +static __always_inline bool rcu_needs_irq_enter(void) > +{ > + return !IS_ENABLED(CONFIG_TINY_RCU) && > + (context_tracking_enabled_cpu(smp_processor_id()) || is_idle_task(current)); This reintroduces the #PF problem which started the whole conditional RCU entry discussion: https://lore.kernel.org/lkml/20200515235125.628629605@linutronix.de/ and which made us all come to the conclusion that we can do it always conditional. No biscuit for you. :) Thanks, tglx