From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932828AbcHNSFm (ORCPT ); Sun, 14 Aug 2016 14:05:42 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54968 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753105AbcHNSAc (ORCPT ); Sun, 14 Aug 2016 14:00:32 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "WANG Cong" , "David S. Miller" , "Jamal Hadi Salim" , "Eric Dumazet" Date: Sat, 13 Aug 2016 18:42:51 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 193/305] net_sched: fix pfifo_head_drop behavior vs backlog In-Reply-To: X-SA-Exim-Connect-IP: 92.40.249.202 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.37-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 6c0d54f1897d229748d4f41ef919078db6db2123 upstream. When the qdisc is full, we drop a packet at the head of the queue, queue the current skb and return NET_XMIT_CN Now we track backlog on upper qdiscs, we need to call qdisc_tree_reduce_backlog(), even if the qlen did not change. Fixes: 2ccccf5fb43f ("net_sched: update hierarchical backlog too") Signed-off-by: Eric Dumazet Cc: WANG Cong Cc: Jamal Hadi Salim Acked-by: Cong Wang Signed-off-by: David S. Miller [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- net/sched/sch_fifo.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/net/sched/sch_fifo.c +++ b/net/sched/sch_fifo.c @@ -37,14 +37,18 @@ static int pfifo_enqueue(struct sk_buff static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch) { + unsigned int prev_backlog; + if (likely(skb_queue_len(&sch->q) < sch->limit)) return qdisc_enqueue_tail(skb, sch); + prev_backlog = sch->qstats.backlog; /* queue full, remove one skb to fulfill the limit */ __qdisc_queue_drop_head(sch, &sch->q); sch->qstats.drops++; qdisc_enqueue_tail(skb, sch); + qdisc_tree_reduce_backlog(sch, 0, prev_backlog - sch->qstats.backlog); return NET_XMIT_CN; }