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=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 687F8C4332E for ; Wed, 6 Jan 2021 04:51:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 267BE22CE3 for ; Wed, 6 Jan 2021 04:51:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727195AbhAFEu5 (ORCPT ); Tue, 5 Jan 2021 23:50:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:34388 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727191AbhAFEu5 (ORCPT ); Tue, 5 Jan 2021 23:50:57 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A21F623106; Wed, 6 Jan 2021 04:48:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1609908540; bh=+nyg0HbAXghhDDYanpwv9o5k98g9Mx695vVR3eZM25E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FWS/ryTHEEaDMpSm8oqcfDLPC+Jia1626frF7I7n+h97ymdg57IaWQ53Nw5XNKH3C eEubxaZqRIYmvlM1XuW88edP0/X1FhVjz2Xx0YpGl/u9D8Ye9k8JJLDiZXNzifLdA9 OFC+I77lhUYbIpav4bsUIbhLDl5mBpxu+bStUHGwRC38JbcFSwNxfuFRuqvh/TWpz5 3VdK5G60Zs8eJeWXjexEFc87vFhi3ElGGAQuLUsJIumQ0LeYtFjPKGbQZcUNrpwtzA rz6ojYp/KglTJVcxrOFsEj76ssfzmnM4ecIIQD1cFjG0CPoyB5cojM33s+2z+iiRPH +8DIp8B9oQu0g== From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 21/21] rcu: Do any deferred nocb wakeups at CPU offline time Date: Tue, 5 Jan 2021 20:48:53 -0800 Message-Id: <20210106044853.20812-21-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20210106013950.GA14663@paulmck-ThinkPad-P72> References: <20210106013950.GA14663@paulmck-ThinkPad-P72> Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: "Paul E. McKenney" Because the need to wake a nocb GP kthread ("rcuog") is sometimes detected when wakeups cannot be done, these wakeups can be deferred. The wakeups are then carried out by calls to do_nocb_deferred_wakeup() at various safe points in the code, including RCU's idle hooks. However, when a CPU goes offline, it invokes arch_cpu_idle_dead() without invoking any of RCU's idle hooks. This commit therefore adds a call to do_nocb_deferred_wakeup() in rcu_report_dead() in order to handle any deferred wakeups that have been requested by the outgoing CPU. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 03810a5..e6dee71 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4178,6 +4178,9 @@ void rcu_report_dead(unsigned int cpu) struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */ + // Do any dangling deferred wakeups. + do_nocb_deferred_wakeup(rdp); + /* QS for any half-done expedited grace period. */ preempt_disable(); rcu_report_exp_rdp(this_cpu_ptr(&rcu_data)); -- 2.9.5