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=-10.1 required=3.0 tests=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 1F5EBC43331 for ; Tue, 24 Mar 2020 15:39:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFF1C2073E for ; Tue, 24 Mar 2020 15:39:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585064377; bh=HtIRk6SgACDcRR+T26oZFJ9RbFoiC+0T7/ZIAIszoac=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NzmFlUGXE5nJOZFh/G8efnzofND7G6+y9om2p3dx16z2tb7vfWMurfBp+WGyFl5C6 lOz2Kuajf0op648aXOaOynigyvMKoKZ8GqFIJ1lDN8wcx70dqmQWkPy1naq/RhntzN XzzTSC7RUiSdwjnwwV3rBX1JcbqjsJAx89KKNwoA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728761AbgCXPjf (ORCPT ); Tue, 24 Mar 2020 11:39:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:59726 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727216AbgCXPhG (ORCPT ); Tue, 24 Mar 2020 11:37:06 -0400 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (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 D0F75208CA; Tue, 24 Mar 2020 15:37:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585064225; bh=HtIRk6SgACDcRR+T26oZFJ9RbFoiC+0T7/ZIAIszoac=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PFTF6dbidKK8bNsgiuQ0YzqiFJ+943Y1octiEX2ks522jykL3FeaoEC3/EpDpuGxK iSRCdwylEHOAzHH1M8Ru71ywTMdX5d3vcvYKSCwuwDdqH30UHL4KfqwkSoefwChV6R R1D6o74rD1071XZ6dlZnno/5DtUel35g3aexpV9w= From: Will Deacon To: linux-kernel@vger.kernel.org Cc: Will Deacon , Eric Dumazet , Jann Horn , Kees Cook , Maddie Stone , Marco Elver , "Paul E . McKenney" , Peter Zijlstra , Thomas Gleixner , kernel-team@android.com, kernel-hardening@lists.openwall.com Subject: [RFC PATCH 06/21] list: Remove superfluous WRITE_ONCE() from hlist_nulls implementation Date: Tue, 24 Mar 2020 15:36:28 +0000 Message-Id: <20200324153643.15527-7-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200324153643.15527-1-will@kernel.org> References: <20200324153643.15527-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 860c8802ace1 ("rcu: Use WRITE_ONCE() for assignments to ->pprev for hlist_nulls") added WRITE_ONCE() invocations to hlist_nulls_add_head() and hlist_nulls_del(). Since these functions should not ordinarily run concurrently with other list accessors, restore the plain C assignments so that KCSAN can yell if a data race occurs. Cc: Eric Dumazet Cc: Paul E. McKenney Cc: Peter Zijlstra Signed-off-by: Will Deacon --- include/linux/list_nulls.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h index fa51a801bf32..fd154ceb5b0d 100644 --- a/include/linux/list_nulls.h +++ b/include/linux/list_nulls.h @@ -80,10 +80,10 @@ static inline void hlist_nulls_add_head(struct hlist_nulls_node *n, struct hlist_nulls_node *first = h->first; n->next = first; - WRITE_ONCE(n->pprev, &h->first); + n->pprev = &h->first; h->first = n; if (!is_a_nulls(first)) - WRITE_ONCE(first->pprev, &n->next); + first->pprev = &n->next; } static inline void __hlist_nulls_del(struct hlist_nulls_node *n) @@ -99,7 +99,7 @@ static inline void __hlist_nulls_del(struct hlist_nulls_node *n) static inline void hlist_nulls_del(struct hlist_nulls_node *n) { __hlist_nulls_del(n); - WRITE_ONCE(n->pprev, LIST_POISON2); + n->pprev = LIST_POISON2; } /** -- 2.20.1