Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755974AbcDLGqH (ORCPT ); Tue, 12 Apr 2016 02:46:07 -0400 Received: from bastet.se.axis.com ([195.60.68.11]:32888 "EHLO bastet.se.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752756AbcDLGqF (ORCPT ); Tue, 12 Apr 2016 02:46:05 -0400 From: Lars Persson To: netdev@vger.kernel.org Cc: jhs@mojatatu.com, linux-kernel@vger.kernel.org, xiyou.wangcong@gmail.com, eric.dumazet@gmail.com, Lars Persson Subject: [PATCH net v3] net: sched: do not requeue a NULL skb Date: Tue, 12 Apr 2016 08:45:52 +0200 Message-Id: <1460443552-26710-1-git-send-email-larper@axis.com> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1263 Lines: 40 A failure in validate_xmit_skb_list() triggered an unconditional call to dev_requeue_skb with skb=NULL. This slowly grows the queue discipline's qlen count until all traffic through the queue stops. We take the optimistic approach and continue running the queue after a failure since it is unknown if later packets also will fail in the validate path. Fixes: 55a93b3ea780 ("qdisc: validate skb without holding lock") Signed-off-by: Lars Persson --- v3: After a discussion with Eric and Cong I went back to v1 and added the likely() for the common path. --- net/sched/sch_generic.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index f18c350..80742ed 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -159,12 +159,15 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q, if (validate) skb = validate_xmit_skb_list(skb, dev); - if (skb) { + if (likely(skb)) { HARD_TX_LOCK(dev, txq, smp_processor_id()); if (!netif_xmit_frozen_or_stopped(txq)) skb = dev_hard_start_xmit(skb, dev, txq, &ret); HARD_TX_UNLOCK(dev, txq); + } else { + spin_lock(root_lock); + return qdisc_qlen(q); } spin_lock(root_lock); -- 2.1.4