From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54C32C47404 for ; Wed, 2 Oct 2019 19:09:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CD552133F for ; Wed, 2 Oct 2019 19:09:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729722AbfJBTJz (ORCPT ); Wed, 2 Oct 2019 15:09:55 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35952 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729335AbfJBTIS (ORCPT ); Wed, 2 Oct 2019 15:08:18 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iFjyx-000364-Qb; Wed, 02 Oct 2019 20:08:15 +0100 Received: from ben by deadeye with local (Exim 4.92.1) (envelope-from ) id 1iFjyp-0003fP-K9; Wed, 02 Oct 2019 20:08:07 +0100 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, Denis Kirjanov , "Dirk van der Merwe" , "Jakub Kicinski" , "Cong Wang" , "David S. Miller" Date: Wed, 02 Oct 2019 20:06:51 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 69/87] net: netem: fix backlog accounting for corrupted GSO frames In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.75-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jakub Kicinski commit 177b8007463c4f36c9a2c7ce7aa9875a4cad9bd5 upstream. When GSO frame has to be corrupted netem uses skb_gso_segment() to produce the list of frames, and re-enqueues the segments one by one. The backlog length has to be adjusted to account for new frames. The current calculation is incorrect, leading to wrong backlog lengths in the parent qdisc (both bytes and packets), and incorrect packet backlog count in netem itself. Parent backlog goes negative, netem's packet backlog counts all non-first segments twice (thus remaining non-zero even after qdisc is emptied). Move the variables used to count the adjustment into local scope to make 100% sure they aren't used at any stage in backports. Fixes: 6071bd1aa13e ("netem: Segment GSO packets on enqueue") Signed-off-by: Jakub Kicinski Reviewed-by: Dirk van der Merwe Acked-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/sched/sch_netem.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -440,8 +440,7 @@ static int netem_enqueue(struct sk_buff struct netem_skb_cb *cb; struct sk_buff *skb2; struct sk_buff *segs = NULL; - unsigned int len = 0, last_len, prev_len = qdisc_pkt_len(skb); - int nb = 0; + unsigned int prev_len = qdisc_pkt_len(skb); int count = 1; int rc = NET_XMIT_SUCCESS; int rc_drop = NET_XMIT_DROP; @@ -495,6 +494,7 @@ static int netem_enqueue(struct sk_buff segs = netem_segment(skb, sch); if (!segs) return rc_drop; + qdisc_skb_cb(segs)->pkt_len = segs->len; } else { segs = skb; } @@ -575,6 +575,11 @@ static int netem_enqueue(struct sk_buff finish_segs: if (segs) { + unsigned int len, last_len; + int nb = 0; + + len = skb->len; + while (segs) { skb2 = segs->next; segs->next = NULL; @@ -590,9 +595,7 @@ finish_segs: } segs = skb2; } - sch->q.qlen += nb; - if (nb > 1) - qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len); + qdisc_tree_reduce_backlog(sch, -nb, prev_len - len); } return NET_XMIT_SUCCESS; }