From patchwork Tue Aug 16 12:48:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 12944869 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CBEEC2BB41 for ; Tue, 16 Aug 2022 12:49:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232763AbiHPMtx (ORCPT ); Tue, 16 Aug 2022 08:49:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233914AbiHPMti (ORCPT ); Tue, 16 Aug 2022 08:49:38 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1002591096; Tue, 16 Aug 2022 05:49:11 -0700 (PDT) Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4M6W9C0r2wzlVpX; Tue, 16 Aug 2022 20:46:07 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 16 Aug 2022 20:49:09 +0800 Received: from thunder-town.china.huawei.com (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 16 Aug 2022 20:49:09 +0800 From: Zhen Lei To: "Paul E . McKenney" , Frederic Weisbecker , Neeraj Upadhyay , "Josh Triplett" , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , , CC: Zhen Lei Subject: [PATCH v3 1/2] rcu: Eliminate rcu_state.nocb_is_setup Date: Tue, 16 Aug 2022 20:48:38 +0800 Message-ID: <20220816124839.1911-2-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 In-Reply-To: <20220816124839.1911-1-thunder.leizhen@huawei.com> References: <20220816124839.1911-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org 'rcu_state.nocb_is_setup' is initialized to true only if 'rcu_nocb_mask' successfully allocates memory. So it can be replaced by 'cpumask_available(rcu_nocb_mask)'. More importantly, the latter is more intuitive, and it has been used in several places. Signed-off-by: Zhen Lei --- kernel/rcu/tree.h | 1 - kernel/rcu/tree_nocb.h | 8 +++----- 2 files changed, 3 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index d4a97e40ea9c3e2..06f659c63d2d192 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -375,7 +375,6 @@ struct rcu_state { arch_spinlock_t ofl_lock ____cacheline_internodealigned_in_smp; /* Synchronize offline with */ /* GP pre-initialization. */ - int nocb_is_setup; /* nocb is setup from boot */ }; /* Values for rcu_state structure's gp_flags field. */ diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index 0a5f0ef41484518..ff763e7dc53551f 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -69,7 +69,6 @@ static int __init rcu_nocb_setup(char *str) cpumask_setall(rcu_nocb_mask); } } - rcu_state.nocb_is_setup = true; return 1; } __setup("rcu_nocbs", rcu_nocb_setup); @@ -1215,7 +1214,7 @@ void __init rcu_init_nohz(void) struct rcu_data *rdp; #if defined(CONFIG_RCU_NOCB_CPU_DEFAULT_ALL) - if (!rcu_state.nocb_is_setup) { + if (!cpumask_available(rcu_nocb_mask)) { need_rcu_nocb_mask = true; offload_all = true; } @@ -1235,10 +1234,9 @@ void __init rcu_init_nohz(void) return; } } - rcu_state.nocb_is_setup = true; } - if (!rcu_state.nocb_is_setup) + if (!cpumask_available(rcu_nocb_mask)) return; #if defined(CONFIG_NO_HZ_FULL) @@ -1299,7 +1297,7 @@ static void rcu_spawn_cpu_nocb_kthread(int cpu) struct task_struct *t; struct sched_param sp; - if (!rcu_scheduler_fully_active || !rcu_state.nocb_is_setup) + if (!rcu_scheduler_fully_active || !cpumask_available(rcu_nocb_mask)) return; /* If there already is an rcuo kthread, then nothing to do. */ From patchwork Tue Aug 16 12:48:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 12944870 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 525CCC32792 for ; Tue, 16 Aug 2022 12:49:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233728AbiHPMty (ORCPT ); Tue, 16 Aug 2022 08:49:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233988AbiHPMtj (ORCPT ); Tue, 16 Aug 2022 08:49:39 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 702BA80356; Tue, 16 Aug 2022 05:49:12 -0700 (PDT) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4M6WBC3YwnzXprQ; Tue, 16 Aug 2022 20:46:59 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 16 Aug 2022 20:49:10 +0800 Received: from thunder-town.china.huawei.com (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 16 Aug 2022 20:49:09 +0800 From: Zhen Lei To: "Paul E . McKenney" , Frederic Weisbecker , Neeraj Upadhyay , "Josh Triplett" , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , , CC: Zhen Lei Subject: [PATCH v3 2/2] rcu: Simplify the code logic of rcu_init_nohz() Date: Tue, 16 Aug 2022 20:48:39 +0800 Message-ID: <20220816124839.1911-3-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 In-Reply-To: <20220816124839.1911-1-thunder.leizhen@huawei.com> References: <20220816124839.1911-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org When CONFIG_RCU_NOCB_CPU_DEFAULT_ALL=y or CONFIG_NO_HZ_FULL=y, additional CPUs need to be added to 'rcu_nocb_mask'. But 'rcu_nocb_mask' may be not available now, due to 'rcu_nocbs' is not specified. Check and initialize 'rcu_nocb_mask' before using it. This code simplification strictly follows this logic, compared with old implementations, unnecessary crossovers are avoided and easy to understand. Signed-off-by: Zhen Lei Reported-by: kernel test robot Reported-by: kernel test robot Reported-by: kernel test robot --- kernel/rcu/tree_nocb.h | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-) diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index ff763e7dc53551f..07b415e8117a10a 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1209,44 +1209,30 @@ EXPORT_SYMBOL_GPL(rcu_nocb_cpu_offload); void __init rcu_init_nohz(void) { int cpu; - bool need_rcu_nocb_mask = false; - bool offload_all = false; struct rcu_data *rdp; + struct cpumask *cpumask = NULL; #if defined(CONFIG_RCU_NOCB_CPU_DEFAULT_ALL) - if (!cpumask_available(rcu_nocb_mask)) { - need_rcu_nocb_mask = true; - offload_all = true; - } -#endif /* #if defined(CONFIG_RCU_NOCB_CPU_DEFAULT_ALL) */ - -#if defined(CONFIG_NO_HZ_FULL) - if (tick_nohz_full_running && !cpumask_empty(tick_nohz_full_mask)) { - need_rcu_nocb_mask = true; - offload_all = false; /* NO_HZ_FULL has its own mask. */ - } -#endif /* #if defined(CONFIG_NO_HZ_FULL) */ + cpumask = cpu_possible_mask; +#elif defined(CONFIG_NO_HZ_FULL) + if (tick_nohz_full_running && !cpumask_empty(tick_nohz_full_mask)) + cpumask = tick_nohz_full_mask; +#endif - if (need_rcu_nocb_mask) { + if (cpumask) { if (!cpumask_available(rcu_nocb_mask)) { if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) { pr_info("rcu_nocb_mask allocation failed, callback offloading disabled.\n"); return; } } + + cpumask_or(rcu_nocb_mask, rcu_nocb_mask, cpumask); } if (!cpumask_available(rcu_nocb_mask)) return; -#if defined(CONFIG_NO_HZ_FULL) - if (tick_nohz_full_running) - cpumask_or(rcu_nocb_mask, rcu_nocb_mask, tick_nohz_full_mask); -#endif /* #if defined(CONFIG_NO_HZ_FULL) */ - - if (offload_all) - cpumask_setall(rcu_nocb_mask); - if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) { pr_info("\tNote: kernel parameter 'rcu_nocbs=', 'nohz_full', or 'isolcpus=' contains nonexistent CPUs.\n"); cpumask_and(rcu_nocb_mask, cpu_possible_mask,