From patchwork Tue Apr 5 07:26:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 557930 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 9AC35C3527A for ; Tue, 5 Apr 2022 08:37:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242198AbiDEIhO (ORCPT ); Tue, 5 Apr 2022 04:37:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235568AbiDEIVa (ORCPT ); Tue, 5 Apr 2022 04:21:30 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB2FE2196; Tue, 5 Apr 2022 01:19:17 -0700 (PDT) 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 2CB4360B12; Tue, 5 Apr 2022 08:19:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37F55C385A0; Tue, 5 Apr 2022 08:19:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649146756; bh=fUO8fVrX1Jo52Tl8cdXg4tG8zouKK4Q2Jo6qUwezPwQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f0G9tQllYSKIWjzEA5PgcYmqBdMdRs+VYP1uBp8qXa7DW521PLreQgWe5OH6nxFfV hyFiddRPlBwTFjkPdKKHh34paHpXcZKjSg4Gxspcl9kyfBov7k8ByOLN8n7/pzGhVV b2zSsDX+z/2Hwb4eMnhzO75orSdkNP5oNqgp+mb4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhouyi Zhou , "Paul E. McKenney" , Frederic Weisbecker , Sasha Levin Subject: [PATCH 5.17 0840/1126] rcu: Mark writes to the rcu_segcblist structures ->flags field Date: Tue, 5 Apr 2022 09:26:27 +0200 Message-Id: <20220405070432.210797778@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paul E. McKenney [ Upstream commit c09929031018913b5783872a8b8cdddef4a543c7 ] KCSAN reports data races between the rcu_segcblist_clear_flags() and rcu_segcblist_set_flags() functions, though misreporting the latter as a call to rcu_segcblist_is_enabled() from call_rcu(). This commit converts the updates of this field to WRITE_ONCE(), relying on the resulting unmarked reads to continue to detect buggy concurrent writes to this field. Reported-by: Zhouyi Zhou Signed-off-by: Paul E. McKenney Cc: Frederic Weisbecker Signed-off-by: Sasha Levin --- kernel/rcu/rcu_segcblist.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h index e373fbe44da5..431cee212467 100644 --- a/kernel/rcu/rcu_segcblist.h +++ b/kernel/rcu/rcu_segcblist.h @@ -56,13 +56,13 @@ static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp) static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp, int flags) { - rsclp->flags |= flags; + WRITE_ONCE(rsclp->flags, rsclp->flags | flags); } static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp, int flags) { - rsclp->flags &= ~flags; + WRITE_ONCE(rsclp->flags, rsclp->flags & ~flags); } static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,