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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 E1950C48BD7 for ; Thu, 27 Jun 2019 13:42:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B78982086D for ; Thu, 27 Jun 2019 13:42:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="crqFv+rk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726706AbfF0Nmo (ORCPT ); Thu, 27 Jun 2019 09:42:44 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:41135 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726443AbfF0Nmo (ORCPT ); Thu, 27 Jun 2019 09:42:44 -0400 Received: by mail-pf1-f195.google.com with SMTP id m30so1257504pff.8 for ; Thu, 27 Jun 2019 06:42:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=BtdsLOtQbtH6zKyvscmgyhI/GvHwrfKtnH8oDV0gzA8=; b=crqFv+rkJGDvzPMA/Ahg1xqSMWqLhFPoHEEyOLgiWFVafqwomj8WEtbgq8URsrg+sV 5Up3Co9q5LvlHbYBRqeZx0a+7JqHN02Pp4T8xzj07t0UBYw0oTRiOxbmjOcN91cOrD4f DIA6KLXQaf1oktcFJEGPrL6hzP9DhCqRzaGLw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=BtdsLOtQbtH6zKyvscmgyhI/GvHwrfKtnH8oDV0gzA8=; b=pO135Fxx14mUvsAWeHB4QJbV+37BfLyjC8vMLu8WB8dZCW1JnzgE2btDnt9dREV9PS 6Qr5UrC6fvULPfjf0XDFbZdkO+Ecim8YNzWIJW0nYPLwqZHJXBh/ttLRAogkvWHS6wq6 kkVGuZp6+USbsCGmX6I56+wQX/X6qu3+35mC3OsCUbc2GvKey4lSC5oV5kWOFF7sJ2mn MDDXfKwLlryz15jnpNU9l3374/VY0lv3LqUCPk8n452CaJER7yZrkymFMJXY2bttSkqU sphHVgvtFW2MF5lp7QokAlzfYOe/bfmIVx35vRrzgpEB1ogH+hkWkuuYFXsnCo72LLlU n0kQ== X-Gm-Message-State: APjAAAWPSE21rIIKv+hZcnzpp0Wnrg9Wq316A+M9UZDYmJqNts+RWzTR iz8dDtKc0JyDPoyNsHdSmulw/A== X-Google-Smtp-Source: APXvYqwvunFjpo4rQbmx8qfoCMvtne65a1y5eBzNzjKK9wQZrE/fgEsLypXFRUL03I7VFEiGY2PvPw== X-Received: by 2002:a63:c5:: with SMTP id 188mr3916108pga.108.1561642963015; Thu, 27 Jun 2019 06:42:43 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id h11sm3471957pfn.170.2019.06.27.06.42.41 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Thu, 27 Jun 2019 06:42:42 -0700 (PDT) Date: Thu, 27 Jun 2019 09:42:40 -0400 From: Joel Fernandes To: Byungchul Park Cc: paulmck@linux.ibm.com, 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: <20190627134240.GB215968@google.com> References: <1561619266-8850-1-git-send-email-byungchul.park@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1561619266-8850-1-git-send-email-byungchul.park@lge.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 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) - 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 >