From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44434 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030693AbeCSSPB (ORCPT ); Mon, 19 Mar 2018 14:15:01 -0400 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 4.4 040/134] bonding: refine bond_fold_stats() wrap detection Date: Mon, 19 Mar 2018 19:05:23 +0100 Message-Id: <20180319171855.117165172@linuxfoundation.org> In-Reply-To: <20180319171849.024066323@linuxfoundation.org> References: <20180319171849.024066323@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 142c6594acbcc32391af9c15f8cd65c6c177698f ] Some device drivers reset their stats at down/up events, possibly fooling bonding stats, since they operate with relative deltas. It is nearly not possible to fix drivers, since some of them compute the tx/rx counters based on per rx/tx queue stats, and the queues can be reconfigured (ethtool -L) between the down/up sequence. Lets avoid accumulating 'negative' values that render bonding stats useless. It is better to lose small deltas, assuming the bonding stats are fetched at a reasonable frequency. Fixes: 5f0c5f73e5ef ("bonding: make global bonding stats more reliable") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/net/bonding/bond_main.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -3276,12 +3276,17 @@ static void bond_fold_stats(struct rtnl_ for (i = 0; i < sizeof(*_res) / sizeof(u64); i++) { u64 nv = new[i]; u64 ov = old[i]; + s64 delta = nv - ov; /* detects if this particular field is 32bit only */ if (((nv | ov) >> 32) == 0) - res[i] += (u32)nv - (u32)ov; - else - res[i] += nv - ov; + delta = (s64)(s32)((u32)nv - (u32)ov); + + /* filter anomalies, some drivers reset their stats + * at down/up events. + */ + if (delta > 0) + res[i] += delta; } }