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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 66CCAC2D0CE for ; Sun, 29 Dec 2019 18:04:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 39C05206A4 for ; Sun, 29 Dec 2019 18:04:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577642694; bh=0Fx2AptUmbnqJWwERQvM0/rovHRB++dwMACcgyDFEv4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=VVbJKZ0CYyXmCDxvVwDlOOjfJud2xVMYkJxnLvhA0ln4i+U5wXfL1mnLg/NurdpwY zAA3bx35v8NMsj8saMBWknEg1eB9qZhBt1Rp2aSwB/Qsg2Zwm0vhwSFl/67C+uEctt RjL6IDnqbGy3RDZidvJjaH7zah082knvSiAI+ceI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732146AbfL2Rvv (ORCPT ); Sun, 29 Dec 2019 12:51:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:37530 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732164AbfL2Rvt (ORCPT ); Sun, 29 Dec 2019 12:51:49 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A2D5A21744; Sun, 29 Dec 2019 17:51:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577641909; bh=0Fx2AptUmbnqJWwERQvM0/rovHRB++dwMACcgyDFEv4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GuzDou2oEQf5MytU/XEIdw8gLz/sba2eT5kD+V9/Ufl6DzVVa30Qwz6iO2cjCTv+X v0j1jnjMZvDNvEs7vGsqGbwkSNJemN5OGAljx/2loy4leoHEadUnbEutz/NVN0fRvQ Yp8y0dnIjz3qPobrqsHSX6E29QcQRORkh+1sM6E4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 262/434] net: avoid potential false sharing in neighbor related code Date: Sun, 29 Dec 2019 18:25:15 +0100 Message-Id: <20191229172719.339035761@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191229172702.393141737@linuxfoundation.org> References: <20191229172702.393141737@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit 25c7a6d1f90e208ec27ca854b1381ed39842ec57 ] There are common instances of the following construct : if (n->confirmed != now) n->confirmed = now; A C compiler could legally remove the conditional. Use READ_ONCE()/WRITE_ONCE() to avoid this problem. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/net/arp.h | 4 ++-- include/net/ndisc.h | 8 ++++---- include/net/sock.h | 12 ++++++------ 3 files changed, 12 insertions(+), 12 deletions(-) diff --git a/include/net/arp.h b/include/net/arp.h index c8f580a0e6b1..4950191f6b2b 100644 --- a/include/net/arp.h +++ b/include/net/arp.h @@ -57,8 +57,8 @@ static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key) unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); } rcu_read_unlock_bh(); } diff --git a/include/net/ndisc.h b/include/net/ndisc.h index b2f715ca0567..b5ebeb3b0de0 100644 --- a/include/net/ndisc.h +++ b/include/net/ndisc.h @@ -414,8 +414,8 @@ static inline void __ipv6_confirm_neigh(struct net_device *dev, unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); } rcu_read_unlock_bh(); } @@ -431,8 +431,8 @@ static inline void __ipv6_confirm_neigh_stub(struct net_device *dev, unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); } rcu_read_unlock_bh(); } diff --git a/include/net/sock.h b/include/net/sock.h index 718e62fbe869..013396e50b91 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1940,8 +1940,8 @@ struct dst_entry *sk_dst_check(struct sock *sk, u32 cookie); static inline void sk_dst_confirm(struct sock *sk) { - if (!sk->sk_dst_pending_confirm) - sk->sk_dst_pending_confirm = 1; + if (!READ_ONCE(sk->sk_dst_pending_confirm)) + WRITE_ONCE(sk->sk_dst_pending_confirm, 1); } static inline void sock_confirm_neigh(struct sk_buff *skb, struct neighbour *n) @@ -1951,10 +1951,10 @@ static inline void sock_confirm_neigh(struct sk_buff *skb, struct neighbour *n) unsigned long now = jiffies; /* avoid dirtying neighbour */ - if (n->confirmed != now) - n->confirmed = now; - if (sk && sk->sk_dst_pending_confirm) - sk->sk_dst_pending_confirm = 0; + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); + if (sk && READ_ONCE(sk->sk_dst_pending_confirm)) + WRITE_ONCE(sk->sk_dst_pending_confirm, 0); } } -- 2.20.1