From patchwork Fri Oct 13 11:58:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederic Weisbecker X-Patchwork-Id: 13420814 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 3BB56CDB482 for ; Fri, 13 Oct 2023 12:00:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231586AbjJMMA1 (ORCPT ); Fri, 13 Oct 2023 08:00:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231734AbjJMMAA (ORCPT ); Fri, 13 Oct 2023 08:00:00 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E459128; Fri, 13 Oct 2023 04:59:46 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25A8EC433CA; Fri, 13 Oct 2023 11:59:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697198386; bh=FQagvd3jim1vzLZluSHTIHqE/ZMRbbrLCQrXxKWYGq0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=heTtGtSecdsKYa7W/R1Z1z0SeOVDjYpQoDiPFINWnTuMzEiwro6TdB2AJ2E1nasyv /rUdpOgREj3kz73+hwtOZVonmWj1tgEz9Ox0diafReZahnnCNQh0ioxskwXb/j96/z qsM027GELQ42gdQvvLelfGRfuw9gn4Ydk/SkRj0RisnoS6Ih8rpGZXn3TNNAk83jB5 fiaudv4Ny0QD0cyGyUTYXLI9fqJYdfjkdlyYz9RMVKf9shSq+okffjMrLgQ2WCRYKR 023ipCxZezIXwWDvAB5G06Uifv5yUR7QMxPGDy5y5B54gR1EoVwA0nJb94m9hdK18i Wlg9YIpDberpw== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Boqun Feng , Joel Fernandes , Josh Triplett , Mathieu Desnoyers , Neeraj Upadhyay , "Paul E . McKenney" , Steven Rostedt , Uladzislau Rezki , rcu Subject: [PATCH 13/18] rcu: Assume rcu_report_dead() is always called locally Date: Fri, 13 Oct 2023 13:58:57 +0200 Message-Id: <20231013115902.1059735-14-frederic@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231013115902.1059735-1-frederic@kernel.org> References: <20231013115902.1059735-1-frederic@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org rcu_report_dead() has to be called locally by the CPU that is going to exit the RCU state machine. Passing a cpu argument here is error-prone and leaves the possibility for a racy remote call. Use local access instead. Reviewed-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker --- arch/arm64/kernel/smp.c | 2 +- include/linux/rcupdate.h | 2 +- kernel/cpu.c | 2 +- kernel/rcu/tree.c | 4 ++-- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 960b98b43506..8fa646c90c67 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -401,7 +401,7 @@ void __noreturn cpu_die_early(void) /* Mark this CPU absent */ set_cpu_present(cpu, 0); - rcu_report_dead(cpu); + rcu_report_dead(); if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { update_cpu_boot_status(CPU_KILL_ME); diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 5e5f920ade90..aa351ddcbe8d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -122,7 +122,7 @@ static inline void call_rcu_hurry(struct rcu_head *head, rcu_callback_t func) void rcu_init(void); extern int rcu_scheduler_active; void rcu_sched_clock_irq(int user); -void rcu_report_dead(unsigned int cpu); +void rcu_report_dead(void); void rcutree_migrate_callbacks(int cpu); #ifdef CONFIG_TASKS_RCU_GENERIC diff --git a/kernel/cpu.c b/kernel/cpu.c index 6de7c6bb74ee..076e75fed8bb 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1388,7 +1388,7 @@ void cpuhp_report_idle_dead(void) struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); BUG_ON(st->state != CPUHP_AP_OFFLINE); - rcu_report_dead(smp_processor_id()); + rcu_report_dead(); st->state = CPUHP_AP_IDLE_DEAD; /* * We cannot call complete after rcu_report_dead() so we delegate it diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 8c2954502e55..2e1e7eadf2cc 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4560,11 +4560,11 @@ void rcu_cpu_starting(unsigned int cpu) * from the outgoing CPU rather than from the cpuhp_step mechanism. * This is because this function must be invoked at a precise location. */ -void rcu_report_dead(unsigned int cpu) +void rcu_report_dead(void) { unsigned long flags; unsigned long mask; - struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu); + struct rcu_data *rdp = this_cpu_ptr(&rcu_data); struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */ /*