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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 25D84C47082 for ; Mon, 31 May 2021 14:59:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0AA80610A0 for ; Mon, 31 May 2021 14:59:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233213AbhEaPBM (ORCPT ); Mon, 31 May 2021 11:01:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:39886 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232956AbhEaOG3 (ORCPT ); Mon, 31 May 2021 10:06:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E874A61968; Mon, 31 May 2021 13:38:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622468334; bh=Pk+wRoH3aM90NjcEyh2oeAkB7xg2RvR9VU9bhfGX9BE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k8MX6NuhNbnUWKFQ1HPQg7etYXILfo11dN38ZOm2bAixfXtpR0KlfMraHbX0yAjT+ Ce06tBW/gyE1Uwt30EMYQ1iZFfasE+JCHv/cFe5ccLyPbl8Sox79XCxs02/po8ke69 voQvXKfiHTA1b5jIrVKSK8AA2MtGgFRt7ehDpy80= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tao Liu , Ilya Maximets , "David S. Miller" , Sasha Levin Subject: [PATCH 5.10 205/252] openvswitch: meter: fix race when getting now_ms. Date: Mon, 31 May 2021 15:14:30 +0200 Message-Id: <20210531130704.982387840@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130657.971257589@linuxfoundation.org> References: <20210531130657.971257589@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tao Liu [ Upstream commit e4df1b0c24350a0f00229ff895a91f1072bd850d ] We have observed meters working unexpected if traffic is 3+Gbit/s with multiple connections. now_ms is not pretected by meter->lock, we may get a negative long_delta_ms when another cpu updated meter->used, then: delta_ms = (u32)long_delta_ms; which will be a large value. band->bucket += delta_ms * band->rate; then we get a wrong band->bucket. OpenVswitch userspace datapath has fixed the same issue[1] some time ago, and we port the implementation to kernel datapath. [1] https://patchwork.ozlabs.org/project/openvswitch/patch/20191025114436.9746-1-i.maximets@ovn.org/ Fixes: 96fbc13d7e77 ("openvswitch: Add meter infrastructure") Signed-off-by: Tao Liu Suggested-by: Ilya Maximets Reviewed-by: Ilya Maximets Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/openvswitch/meter.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c index 8fbefd52af7f..e594b4d6b58a 100644 --- a/net/openvswitch/meter.c +++ b/net/openvswitch/meter.c @@ -611,6 +611,14 @@ bool ovs_meter_execute(struct datapath *dp, struct sk_buff *skb, spin_lock(&meter->lock); long_delta_ms = (now_ms - meter->used); /* ms */ + if (long_delta_ms < 0) { + /* This condition means that we have several threads fighting + * for a meter lock, and the one who received the packets a + * bit later wins. Assuming that all racing threads received + * packets at the same time to avoid overflow. + */ + long_delta_ms = 0; + } /* Make sure delta_ms will not be too large, so that bucket will not * wrap around below. -- 2.30.2