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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 28A1AC4321A for ; Fri, 28 Jun 2019 02:44:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 006072086D for ; Fri, 28 Jun 2019 02:44:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726805AbfF1CoX (ORCPT ); Thu, 27 Jun 2019 22:44:23 -0400 Received: from lgeamrelo12.lge.com ([156.147.23.52]:57211 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726476AbfF1CoX (ORCPT ); Thu, 27 Jun 2019 22:44:23 -0400 Received: from unknown (HELO lgemrelse7q.lge.com) (156.147.1.151) by 156.147.23.52 with ESMTP; 28 Jun 2019 11:44:20 +0900 X-Original-SENDERIP: 156.147.1.151 X-Original-MAILFROM: byungchul.park@lge.com Received: from unknown (HELO X58A-UD3R) (10.177.222.33) by 156.147.1.151 with ESMTP; 28 Jun 2019 11:44:20 +0900 X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Fri, 28 Jun 2019 11:43:39 +0900 From: Byungchul Park To: "Paul E. McKenney" Cc: Joel Fernandes , josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@lge.com Subject: Re: [PATCH v2] rcu: Change return type of rcu_spawn_one_boost_kthread() Message-ID: <20190628024339.GA13650@X58A-UD3R> References: <1561619266-8850-1-git-send-email-byungchul.park@lge.com> <20190627134240.GB215968@google.com> <20190627205703.GF26519@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190627205703.GF26519@linux.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 27, 2019 at 01:57:03PM -0700, Paul E. McKenney wrote: > On Thu, Jun 27, 2019 at 09:42:40AM -0400, Joel Fernandes wrote: > > On Thu, Jun 27, 2019 at 04:07:46PM +0900, Byungchul Park wrote: > > > Hello, > > > > > > I tested if the WARN_ON_ONCE() is fired with my box and it was ok. > > > > Looks pretty safe to me and nice clean up! > > > > Acked-by: Joel Fernandes (Google) > > Agreed, but I still cannot find where this applies. I did try rcu/next, > which is currently here: > > commit b989ff070574ad8b8621d866de0a8e9a65d42c80 (rcu/rcu/next, rcu/next) > Merge: 4289ee7d5a83 11ca7a9d541d > Author: Paul E. McKenney > Date: Mon Jun 24 09:12:39 2019 -0700 > > Merge LKMM and RCU commits > > Help? commit 204d7a60670f3f6399a4d0826667ab7863b3e429 Merge LKMM and RCU commits I made it on top of the above. And could you tell me which branch I'd better use when developing. I think it's been changing sometimes. Thank you for the answer in advance! Thanks, Byungchul > Thanx, Paul > > > - Joel > > > > > > > > Thanks, > > > Byungchul > > > > > > Changes from v1 > > > -. WARN_ON_ONCE() on failing to create rcu_boost_kthread. > > > -. Changed title and commit message a bit. > > > > > > ---8<--- > > > From 7100fcf82202f063f70f45def208ea5198412f5a Mon Sep 17 00:00:00 2001 > > > From: Byungchul Park > > > Date: Thu, 27 Jun 2019 15:58:10 +0900 > > > Subject: [PATCH v2] rcu: Change return type of rcu_spawn_one_boost_kthread() > > > > > > The return value of rcu_spawn_one_boost_kthread() is not used any > > > longer. Change return type of that function from int to void. > > > > > > Signed-off-by: Byungchul Park > > > --- > > > kernel/rcu/tree_plugin.h | 17 ++++++++--------- > > > 1 file changed, 8 insertions(+), 9 deletions(-) > > > > > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > > > index 1102765..3c8444e 100644 > > > --- a/kernel/rcu/tree_plugin.h > > > +++ b/kernel/rcu/tree_plugin.h > > > @@ -1131,7 +1131,7 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp) > > > * already exist. We only create this kthread for preemptible RCU. > > > * Returns zero if all is well, a negated errno otherwise. > > > */ > > > -static int rcu_spawn_one_boost_kthread(struct rcu_node *rnp) > > > +static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp) > > > { > > > int rnp_index = rnp - rcu_get_root(); > > > unsigned long flags; > > > @@ -1139,25 +1139,24 @@ static int rcu_spawn_one_boost_kthread(struct rcu_node *rnp) > > > struct task_struct *t; > > > > > > if (!IS_ENABLED(CONFIG_PREEMPT_RCU)) > > > - return 0; > > > + return; > > > > > > if (!rcu_scheduler_fully_active || rcu_rnp_online_cpus(rnp) == 0) > > > - return 0; > > > + return; > > > > > > rcu_state.boost = 1; > > > if (rnp->boost_kthread_task != NULL) > > > - return 0; > > > + return; > > > t = kthread_create(rcu_boost_kthread, (void *)rnp, > > > "rcub/%d", rnp_index); > > > - if (IS_ERR(t)) > > > - return PTR_ERR(t); > > > + if (WARN_ON_ONCE(IS_ERR(t))) > > > + return; > > > raw_spin_lock_irqsave_rcu_node(rnp, flags); > > > rnp->boost_kthread_task = t; > > > raw_spin_unlock_irqrestore_rcu_node(rnp, flags); > > > sp.sched_priority = kthread_prio; > > > sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); > > > wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */ > > > - return 0; > > > } > > > > > > static void rcu_cpu_kthread_setup(unsigned int cpu) > > > @@ -1265,7 +1264,7 @@ static void __init rcu_spawn_boost_kthreads(void) > > > if (WARN_ONCE(smpboot_register_percpu_thread(&rcu_cpu_thread_spec), "%s: Could not start rcub kthread, OOM is now expected behavior\n", __func__)) > > > return; > > > rcu_for_each_leaf_node(rnp) > > > - (void)rcu_spawn_one_boost_kthread(rnp); > > > + rcu_spawn_one_boost_kthread(rnp); > > > } > > > > > > static void rcu_prepare_kthreads(int cpu) > > > @@ -1275,7 +1274,7 @@ static void rcu_prepare_kthreads(int cpu) > > > > > > /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */ > > > if (rcu_scheduler_fully_active) > > > - (void)rcu_spawn_one_boost_kthread(rnp); > > > + rcu_spawn_one_boost_kthread(rnp); > > > } > > > > > > #else /* #ifdef CONFIG_RCU_BOOST */ > > > -- > > > 1.9.1 > > >