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 460E7C433F5 for ; Mon, 28 Mar 2022 11:19:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240693AbiC1LU7 (ORCPT ); Mon, 28 Mar 2022 07:20:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240618AbiC1LU3 (ORCPT ); Mon, 28 Mar 2022 07:20:29 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A319655BC1; Mon, 28 Mar 2022 04:18:46 -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 163F461164; Mon, 28 Mar 2022 11:18:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A3FDC340F3; Mon, 28 Mar 2022 11:18:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648466325; bh=nzRawaQS045Wza+ALG2+UpplqPvhpXdSly+LWy6udjI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dNCmCipPZzrm1HOaccamotJDYZzMQe3RdrPoqH20iyxjGbIo1DYgEt/wAyfaIqJpU menysWj5rPaMT3Ht1R1JyQjGAb/VxYx5n/jQebqRR96VtqQC6/wS0ylSnN8+UN20s3 QMufU1dklsxsMLbtFYpkhYPdLEG4vm7k9L5ARE9QOvF42nOxguk6dgTtXjwbiGrg6H 7U/vgnPiD9d/rSQhx9ZorBY3bquEB/tncwxw0dIFlJRueZn+yTmSskJtGw6EEvUJeh 5jjskZ9TD7T2RUiY4HvqTau65dqP/btcptLgi3wkaIUBLbk+uMf/yS2Ao3YaZpjo3t xYuw1ErCZjgcg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Paul E. McKenney" , Zhouyi Zhou , Frederic Weisbecker , Sasha Levin , quic_neeraju@quicinc.com, josh@joshtriplett.org, rcu@vger.kernel.org Subject: [PATCH AUTOSEL 5.17 08/43] rcu: Mark writes to the rcu_segcblist structure's ->flags field Date: Mon, 28 Mar 2022 07:17:52 -0400 Message-Id: <20220328111828.1554086-8-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220328111828.1554086-1-sashal@kernel.org> References: <20220328111828.1554086-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit 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, -- 2.34.1