From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755578AbcEQB0Z (ORCPT ); Mon, 16 May 2016 21:26:25 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34410 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755469AbcEQBYi (ORCPT ); Mon, 16 May 2016 21:24:38 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lars Persson , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.5 005/101] net: sched: do not requeue a NULL skb Date: Mon, 16 May 2016 18:20:10 -0700 Message-Id: <20160517011506.552026166@linuxfoundation.org> X-Mailer: git-send-email 2.8.2 In-Reply-To: <20160517011506.359924439@linuxfoundation.org> References: <20160517011506.359924439@linuxfoundation.org> User-Agent: quilt/0.64 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 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lars Persson [ Upstream commit 3dcd493fbebfd631913df6e2773cc295d3bf7d22 ] 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 Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_generic.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -159,12 +159,15 @@ int sch_direct_xmit(struct sk_buff *skb, 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);