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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12B55C433F5 for ; Fri, 4 Feb 2022 23:20:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378048AbiBDXUz (ORCPT ); Fri, 4 Feb 2022 18:20:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378039AbiBDXUm (ORCPT ); Fri, 4 Feb 2022 18:20:42 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56358DFBC71F; Fri, 4 Feb 2022 15:20:41 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id A715FCE24B8; Fri, 4 Feb 2022 23:20:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9FDAC340F1; Fri, 4 Feb 2022 23:20:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644016837; bh=S4eE3S6LI0fVFBCvPzoWLKyt6VIRD7KnrVxSw8qANRc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oNoKmx5gENNnY/2V1bzrutS0sYA6WM4B/GMjlKQiXLTKKEnTAyhVXWJ4cyoFNQeAS 4wEy0YO4KGIPtaOcKl1t7d9ohzzF4xFBOhXANuI1YTwNyxsngNePAIsU+KJ5p87XKO 9+bvRFnHcocUSPLpXXUfHtyrqEBFB2HuyffyT4w7n5fmsYHhm3f9urnVZ7QYQDl5mw kEHsmzgDdAE7zj+YEDWv54X9oajDaUZ6TTty2mdGdACNRb4CREa0kZ3q1LgdxKGDg/ N2KVx7vG2YgZOH49WMxZmpYxyDTBoUU307O2faVd9PC1BIqhhrhQtp74jqXr1UP69f uuOlp2KFBsItQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id AA35F5C0992; Fri, 4 Feb 2022 15:20:37 -0800 (PST) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, "Paul E. McKenney" Subject: [PATCH rcu 5/5] rcu: Create and use an rcu_rdp_cpu_online() Date: Fri, 4 Feb 2022 15:20:36 -0800 Message-Id: <20220204232036.460-5-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220204232027.GA4194214@paulmck-ThinkPad-P17-Gen-1> References: <20220204232027.GA4194214@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The pattern "rdp->grpmask & rcu_rnp_online_cpus(rnp)" occurs frequently in RCU code in order to determine whether rdp->cpu is online from an RCU perspective. This commit therefore creates an rcu_rdp_cpu_online() function to replace it. [ paulmck: Apply kernel test robot unused-variable feedback. ] Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 21 +++++++++++++-------- kernel/rcu/tree_plugin.h | 6 ++---- 2 files changed, 15 insertions(+), 12 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 1c30a01692076..6a470bb93b485 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -222,6 +222,16 @@ static unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp) return READ_ONCE(rnp->qsmaskinitnext); } +/* + * Is the CPU corresponding to the specified rcu_data structure online + * from RCU's perspective? This perspective is given by that structure's + * ->qsmaskinitnext field rather than by the global cpu_online_mask. + */ +static bool rcu_rdp_cpu_online(struct rcu_data *rdp) +{ + return !!(rdp->grpmask & rcu_rnp_online_cpus(rdp->mynode)); +} + /* * Return true if an RCU grace period is in progress. The READ_ONCE()s * permit this function to be invoked without holding the root rcu_node @@ -1168,14 +1178,12 @@ void rcu_request_urgent_qs_task(struct task_struct *t) bool rcu_lockdep_current_cpu_online(void) { struct rcu_data *rdp; - struct rcu_node *rnp; bool ret = false; if (in_nmi() || !rcu_scheduler_fully_active) return true; preempt_disable_notrace(); rdp = this_cpu_ptr(&rcu_data); - rnp = rdp->mynode; /* * Strictly, we care here about the case where the current CPU is * in rcu_cpu_starting() and thus has an excuse for rdp->grpmask @@ -1183,8 +1191,7 @@ bool rcu_lockdep_current_cpu_online(void) * false positive if it's held by some *other* CPU, but that's * OK because that just means a false *negative* on the warning. */ - if (rdp->grpmask & rcu_rnp_online_cpus(rnp) || - arch_spin_is_locked(&rcu_state.ofl_lock)) + if (rcu_rdp_cpu_online(rdp) || arch_spin_is_locked(&rcu_state.ofl_lock)) ret = true; preempt_enable_notrace(); return ret; @@ -1269,8 +1276,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) * For more detail, please refer to the "Hotplug CPU" section * of RCU's Requirements documentation. */ - if (WARN_ON_ONCE(!(rdp->grpmask & rcu_rnp_online_cpus(rnp)))) { - bool onl; + if (WARN_ON_ONCE(!rcu_rdp_cpu_online(rdp))) { struct rcu_node *rnp1; pr_info("%s: grp: %d-%d level: %d ->gp_seq %ld ->completedqs %ld\n", @@ -1279,9 +1285,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) for (rnp1 = rnp; rnp1; rnp1 = rnp1->parent) pr_info("%s: %d:%d ->qsmask %#lx ->qsmaskinit %#lx ->qsmaskinitnext %#lx ->rcu_gp_init_mask %#lx\n", __func__, rnp1->grplo, rnp1->grphi, rnp1->qsmask, rnp1->qsmaskinit, rnp1->qsmaskinitnext, rnp1->rcu_gp_init_mask); - onl = !!(rdp->grpmask & rcu_rnp_online_cpus(rnp)); pr_info("%s %d: %c online: %ld(%d) offline: %ld(%d)\n", - __func__, rdp->cpu, ".o"[onl], + __func__, rdp->cpu, ".o"[rcu_rdp_cpu_online(rdp)], (long)rdp->rcu_onl_gp_seq, rdp->rcu_onl_gp_flags, (long)rdp->rcu_ofl_gp_seq, rdp->rcu_ofl_gp_flags); return 1; /* Break things loose after complaining. */ diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index c5b45c2f68a15..d3db2168598ef 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -330,7 +330,7 @@ void rcu_note_context_switch(bool preempt) * then queue the task as required based on the states * of any ongoing and expedited grace periods. */ - WARN_ON_ONCE((rdp->grpmask & rcu_rnp_online_cpus(rnp)) == 0); + WARN_ON_ONCE(!rcu_rdp_cpu_online(rdp)); WARN_ON_ONCE(!list_empty(&t->rcu_node_entry)); trace_rcu_preempt_task(rcu_state.name, t->pid, @@ -773,7 +773,6 @@ dump_blkd_tasks(struct rcu_node *rnp, int ncheck) int cpu; int i; struct list_head *lhp; - bool onl; struct rcu_data *rdp; struct rcu_node *rnp1; @@ -797,9 +796,8 @@ dump_blkd_tasks(struct rcu_node *rnp, int ncheck) pr_cont("\n"); for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++) { rdp = per_cpu_ptr(&rcu_data, cpu); - onl = !!(rdp->grpmask & rcu_rnp_online_cpus(rnp)); pr_info("\t%d: %c online: %ld(%d) offline: %ld(%d)\n", - cpu, ".o"[onl], + cpu, ".o"[rcu_rdp_cpu_online(rdp)], (long)rdp->rcu_onl_gp_seq, rdp->rcu_onl_gp_flags, (long)rdp->rcu_ofl_gp_seq, rdp->rcu_ofl_gp_flags); } -- 2.31.1.189.g2e36527f23