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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 3486DC433E6 for ; Mon, 31 Aug 2020 18:01:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA7D020EDD for ; Mon, 31 Aug 2020 18:01:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598896907; bh=ZpEymyqav3YyMpdsc6ES/niPTHg4XJIiINsSUIRbYEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sBha3MYmm5aiDG6L6BSodNc1L6uOijU3jAcRnesp5n667H57TSj1kHGu6+DopKd5r 1gIX303DHsw10CdkeJiB0YLJ8BvxSGeRo50RKFmtHQBvx5tKwwWzk6V1dCthK+sNrA 6hpevRFD/ejkoyw8KtUooEA5EV39xOaSpB5fntcM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729043AbgHaSBo (ORCPT ); Mon, 31 Aug 2020 14:01:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:36100 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728775AbgHaSB0 (ORCPT ); Mon, 31 Aug 2020 14:01:26 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D5C0C215A4; Mon, 31 Aug 2020 18:01:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598896884; bh=ZpEymyqav3YyMpdsc6ES/niPTHg4XJIiINsSUIRbYEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c3ODGLOpgu8VVg1oeFwi+e1udzdL0dGBwE+29tTqmqFFMnjHNIffWbMNK8N/I5iNc Wtq7TjxwUj6A46BYatfnL2WBZEcXvrEqUYnATVf2DDYRMkmvy/+L3cpGpG5x2rfBDE 8rNJN8lrPDkgmJotUOqoa+98SKzDUqvG/7IYqgZs= 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, dipankar@in.ibm.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 13/24] rcu: Add READ_ONCE() to rcu_do_batch() access to rcu_kick_kthreads Date: Mon, 31 Aug 2020 11:01:05 -0700 Message-Id: <20200831180116.32690-13-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831180050.GA32590@paulmck-ThinkPad-P72> References: <20200831180050.GA32590@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" Given that sysfs can change the value of rcu_kick_kthreads at any time, this commit adds a READ_ONCE() to the sole access to that variable. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_stall.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index b5d3b47..a1780a6 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -158,7 +158,7 @@ static void rcu_stall_kick_kthreads(void) { unsigned long j; - if (!rcu_kick_kthreads) + if (!READ_ONCE(rcu_kick_kthreads)) return; j = READ_ONCE(rcu_state.jiffies_kick_kthreads); if (time_after(jiffies, j) && rcu_state.gp_kthread && @@ -580,7 +580,7 @@ static void check_cpu_stall(struct rcu_data *rdp) unsigned long js; struct rcu_node *rnp; - if ((rcu_stall_is_suppressed() && !rcu_kick_kthreads) || + if ((rcu_stall_is_suppressed() && !READ_ONCE(rcu_kick_kthreads)) || !rcu_gp_in_progress()) return; rcu_stall_kick_kthreads(); -- 2.9.5