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=-8.5 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=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 04EE2C06511 for ; Tue, 2 Jul 2019 08:45:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2F0320659 for ; Tue, 2 Jul 2019 08:45:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727049AbfGBIpj (ORCPT ); Tue, 2 Jul 2019 04:45:39 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:7038 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726105AbfGBIpj (ORCPT ); Tue, 2 Jul 2019 04:45:39 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x628gOiO106364; Tue, 2 Jul 2019 04:45:04 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 2tg346t8fc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 02 Jul 2019 04:45:04 -0400 Received: from m0098396.ppops.net (m0098396.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.27/8.16.0.27) with SMTP id x628j4OB114350; Tue, 2 Jul 2019 04:45:04 -0400 Received: from ppma01wdc.us.ibm.com (fd.55.37a9.ip4.static.sl-reverse.com [169.55.85.253]) by mx0a-001b2d01.pphosted.com with ESMTP id 2tg346t8eg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 02 Jul 2019 04:45:04 -0400 Received: from pps.filterd (ppma01wdc.us.ibm.com [127.0.0.1]) by ppma01wdc.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id x628eNlO007482; Tue, 2 Jul 2019 08:45:02 GMT Received: from b01cxnp22033.gho.pok.ibm.com (b01cxnp22033.gho.pok.ibm.com [9.57.198.23]) by ppma01wdc.us.ibm.com with ESMTP id 2tdym6muks-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 02 Jul 2019 08:45:02 +0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x628j2rO46203150 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 2 Jul 2019 08:45:02 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 80B18B2066; Tue, 2 Jul 2019 08:45:02 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4CAB7B2073; Tue, 2 Jul 2019 08:45:02 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.85.179.41]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 2 Jul 2019 08:45:02 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 6A91D16C5E27; Tue, 2 Jul 2019 01:45:02 -0700 (PDT) Date: Tue, 2 Jul 2019 01:45:02 -0700 From: "Paul E. McKenney" To: Byungchul Park Cc: josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@lge.com Subject: Re: [PATCH v3] rcu: Change return type of rcu_spawn_one_boost_kthread() Message-ID: <20190702084502.GL26519@linux.ibm.com> Reply-To: paulmck@linux.ibm.com References: <1561941639-14318-1-git-send-email-byungchul.park@lge.com> <20190701201216.GQ26519@linux.ibm.com> <20190702051103.GA13132@X58A-UD3R> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190702051103.GA13132@X58A-UD3R> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-02_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907020102 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 02, 2019 at 02:11:03PM +0900, Byungchul Park wrote: > On Mon, Jul 01, 2019 at 01:12:16PM -0700, Paul E. McKenney wrote: > > On Mon, Jul 01, 2019 at 09:40:39AM +0900, Byungchul Park wrote: > > > Hello, > > > > > > I tested again if the WARN_ON_ONCE() is fired with my box. > > > > > > And it was OK. > > > > > > Thanks, > > > Byungchul > > > > And it now applies just fine, so I have queued it, thank you! > > > > In the future, could you please use something like "git send-email" > > to email a proper patch? When you do it this way, after I do "git am", > > I have to hand-edit the commit to remove this preamble. > > Oh! Sorry to hear that. I've been always using "git send-email" with > scissors in the body expecting you do "git am -c". Do you mean it's not > a good way, right? I won't use the scissors again. Ah. First I have heard of the "-c" argument to "git am". OK, now that I know, feel free to continue sending me scissored patches, and thank you for calling my attention to this feature! Actually, I just updated my git config to make "-c" the default. That way I don't have to remember. ;-) Thanx, Paul > > But while I was doing the hand-editing, I updated the commit log as > > follows: > > > > rcu: Change return type of rcu_spawn_one_boost_kthread() > > > > The return value of rcu_spawn_one_boost_kthread() is not used > > any longer. This commit therefore changes its return type from > > int to void, and removes the cast to void from its callers. > > > > Does that work for you? > > Sure. Thank you. > > Thanks, > Byungchul > > > Thanx, Paul > > > > > Changes from v2 > > > -. Port the patch to a1af11a24cb0 (Paul's request) > > > -. Add a few new lines for a better look > > > > > > Changes from v1 > > > -. WARN_ON_ONCE() on failing to create rcu_boost_kthread. > > > -. Changed title and commit message a bit. > > > > > > ---8<--- > > > >From 20c934c5657a7a0f13ebb050ffd350d4174965d0 Mon Sep 17 00:00:00 2001 > > > From: Byungchul Park > > > Date: Mon, 1 Jul 2019 09:27:15 +0900 > > > Subject: [PATCH v3] 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 | 20 +++++++++++--------- > > > 1 file changed, 11 insertions(+), 9 deletions(-) > > > > > > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > > > index c588ef9..b8eea22 100644 > > > --- a/kernel/rcu/tree_plugin.h > > > +++ b/kernel/rcu/tree_plugin.h > > > @@ -1119,7 +1119,7 @@ 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; > > > @@ -1127,25 +1127,27 @@ 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; > > > } > > > > > > /* > > > @@ -1186,7 +1188,7 @@ static void __init rcu_spawn_boost_kthreads(void) > > > struct rcu_node *rnp; > > > > > > 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) > > > @@ -1196,7 +1198,7 @@ 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 > > > >