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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 90572C43381 for ; Thu, 21 Mar 2019 08:27:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 605D7218B0 for ; Thu, 21 Mar 2019 08:27:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728020AbfCUI1m (ORCPT ); Thu, 21 Mar 2019 04:27:42 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:37283 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727881AbfCUI1m (ORCPT ); Thu, 21 Mar 2019 04:27:42 -0400 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1h6t33-0007FC-TW; Thu, 21 Mar 2019 09:27:38 +0100 Date: Thu, 21 Mar 2019 09:27:37 +0100 From: Sebastian Andrzej Siewior To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , tglx@linutronix.de, Mike Galbraith Subject: Re: [PATCH v3] rcu: Allow to eliminate softirq processing from rcutree Message-ID: <20190321082737.t5jhdyuartimamu2@linutronix.de> References: <20190320154440.GA16332@linux.ibm.com> <20190320160547.s5lbeahr2y4jlzwt@linutronix.de> <20190320161500.GK4102@linux.ibm.com> <20190320163532.mr32oi53iaueuizw@linutronix.de> <20190320173001.GM4102@linux.ibm.com> <20190320175952.yh6yfy64vaiurszw@linutronix.de> <20190320181210.GO4102@linux.ibm.com> <20190320181435.x3qyutwqllmq5zbk@linutronix.de> <20190320211333.eq7pwxnte7la67ph@linutronix.de> <20190320234601.GQ4102@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190320234601.GQ4102@linux.ibm.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-03-20 16:46:01 [-0700], Paul E. McKenney wrote: > Thank you! I reverted v2 and applied this one with the same sort of > update. Testing is going well thus far aside from my failing to add > the required "=0" after the rcutree.use_softirq. I will probably not > be the only one who will run afoul of this, so I updated the commit log > and the documentation accordingly, as shown below. perfect, thank you. > Thanx, Paul > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index f46b4af96ab9..b807204ffd83 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -629,7 +609,10 @@ static void rcu_read_unlock_special(struct task_struct *t) > /* Need to defer quiescent state until everything is enabled. */ > if (irqs_were_disabled) { > /* Enabling irqs does not reschedule, so... */ > - raise_softirq_irqoff(RCU_SOFTIRQ); > + if (!use_softirq) that exclamation mark needs to go :/ > + raise_softirq_irqoff(RCU_SOFTIRQ); > + else > + invoke_rcu_core(); > } else { > /* Enabling BH or preempt does reschedule, so... */ > set_tsk_need_resched(current); Sebastian