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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 892E6FC6197 for ; Fri, 8 Nov 2019 22:06:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 501382178F for ; Fri, 8 Nov 2019 22:06:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727672AbfKHWGq (ORCPT ); Fri, 8 Nov 2019 17:06:46 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:39266 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727001AbfKHWGq (ORCPT ); Fri, 8 Nov 2019 17:06:46 -0500 Received: from localhost (unknown [IPv6:2601:601:9f00:1e2::d71]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 8C783153AF3AF; Fri, 8 Nov 2019 14:06:45 -0800 (PST) Date: Fri, 08 Nov 2019 14:06:45 -0800 (PST) Message-Id: <20191108.140645.867365524804910483.davem@davemloft.net> To: edumazet@google.com Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com, willemb@google.com Subject: Re: [PATCH net-next] packet: fix data-race in fanout_flow_is_huge() From: David Miller In-Reply-To: <20191108130746.172131-1-edumazet@google.com> References: <20191108130746.172131-1-edumazet@google.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Fri, 08 Nov 2019 14:06:45 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet Date: Fri, 8 Nov 2019 05:07:46 -0800 > KCSAN reported the following data-race [1] > > Adding a couple of READ_ONCE()/WRITE_ONCE() should silence it. > > Since the report hinted about multiple cpus using the history > concurrently, I added a test avoiding writing on it if the > victim slot already contains the desired value. > > [1] > > BUG: KCSAN: data-race in fanout_demux_rollover / fanout_demux_rollover ... > Fixes: 3b3a5b0aab5b ("packet: rollover huge flows before small flows") > Signed-off-by: Eric Dumazet Applied, thanks Eric.