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 59415C433F5 for ; Fri, 4 Feb 2022 22:55:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355466AbiBDWzM (ORCPT ); Fri, 4 Feb 2022 17:55:12 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:51526 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355228AbiBDWzK (ORCPT ); Fri, 4 Feb 2022 17:55:10 -0500 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 dfw.source.kernel.org (Postfix) with ESMTPS id D876861AE4; Fri, 4 Feb 2022 22:55:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E127C340ED; Fri, 4 Feb 2022 22:55:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644015309; bh=P+ojzxqenLejeCItnmyBFPt2VGf6j96fThZ8UVIBRYw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DHKmctannmKHUrJzHzmcO/yPgn8p9ryi7B1Cs5nyx66lpnHGpzex8Xr5W/Nh2Wi+U jQWn5RHlkeLf3FsrA4RrhVBqVwO6gHGwLu71Q6J22z4bg+NM9SAq83aNSsXdUPUi5Q NXjsIffO2T14PbS7gTqkM91g7yr63CjtUoHeIzB5cKexQ9fI3AjadQRUNrgctJruwJ V2lx0k8r31B8hCIB+tLzjajKdLk30pZ/zofAqrVAZScOOtt/aVEymNKuiyzLfgVzVd cvTSsZNLTGUHe9Szdr4QYbTqzEo5MXmG44VkgDvf2Yi8SjuBbm/EAUYNHjJ+CSIzCV NS+BacmVFB4KA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 0EF305C0829; Fri, 4 Feb 2022 14:55:09 -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 2/3] rcu: Mark ->expmask access in synchronize_rcu_expedited_wait() Date: Fri, 4 Feb 2022 14:55:06 -0800 Message-Id: <20220204225507.4193113-2-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220204225409.GA4193020@paulmck-ThinkPad-P17-Gen-1> References: <20220204225409.GA4193020@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 This commit adds a READ_ONCE() to an access to the rcu_node structure's ->expmask field to prevent compiler mischief. Detected by KCSAN. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_exp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 1568c8ef185b2..60197ea24ceb9 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -502,7 +502,8 @@ static void synchronize_rcu_expedited_wait(void) if (synchronize_rcu_expedited_wait_once(1)) return; rcu_for_each_leaf_node(rnp) { - for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) { + mask = READ_ONCE(rnp->expmask); + for_each_leaf_node_cpu_mask(rnp, cpu, mask) { rdp = per_cpu_ptr(&rcu_data, cpu); if (rdp->rcu_forced_tick_exp) continue; -- 2.31.1.189.g2e36527f23