From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751514AbdH1IGy (ORCPT ); Mon, 28 Aug 2017 04:06:54 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60918 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751187AbdH1IGt (ORCPT ); Mon, 28 Aug 2017 04:06:49 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Konstantin Khlebnikov , Cong Wang , "David S. Miller" Subject: [PATCH 4.12 25/99] net_sched: fix order of queue length updates in qdisc_replace() Date: Mon, 28 Aug 2017 10:04:23 +0200 Message-Id: <20170828080456.970246432@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170828080455.968552605@linuxfoundation.org> References: <20170828080455.968552605@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov [ Upstream commit 68a66d149a8c78ec6720f268597302883e48e9fa ] This important to call qdisc_tree_reduce_backlog() after changing queue length. Parent qdisc should deactivate class in ->qlen_notify() called from qdisc_tree_reduce_backlog() but this happens only if qdisc->q.qlen in zero. Missed class deactivations leads to crashes/warnings at picking packets from empty qdisc and corrupting state at reactivating this class in future. Signed-off-by: Konstantin Khlebnikov Fixes: 86a7996cc8a0 ("net_sched: introduce qdisc_replace() helper") Acked-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/sch_generic.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -785,8 +785,11 @@ static inline struct Qdisc *qdisc_replac old = *pold; *pold = new; if (old != NULL) { - qdisc_tree_reduce_backlog(old, old->q.qlen, old->qstats.backlog); + unsigned int qlen = old->q.qlen; + unsigned int backlog = old->qstats.backlog; + qdisc_reset(old); + qdisc_tree_reduce_backlog(old, qlen, backlog); } sch_tree_unlock(sch);